PIPE
February 15, 2017 | Author: Nelson Naval Cabingas | Category: N/A
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POWER AND INDUSTRIAL PLANT ENGINEERING By:ALCORCON
ME 517AL
Dulnuan, Livingstone R. SUBMITTED BY:
Engr. Michael Carulla SUBMITTED TO:
May 2, 2013
POWER AND INDUSTRIAL PLANT ENGINEERING-ALCORCON THERMODYNAMICS 1. What is the pressure 8,000 ft. (2000m) below the surface of the ocean? Neglect the compressibility factor, SI units. Answer: B A. 21.4 B. 20.1 C. 21.0 D. 22.3 2. What temperature at which water freezes using the Kelvin scale? Answer: B A. 373 B. 273 C. 278 D. 406 3. The SI units of temperature is: Answer: B A. oF B. oK C. BTU D. oR 4. The pressure reading of 35 psi in kpa is: Answer: A A. 342.72 B. 724.00 C. 273.40 D. 427.30 5. 1 torr is equivalent to pressure Answer: D A. 1 atm B. 2mm Hg C. 14.7 D. 1/760 atm 6. What is the standard temperature in the US? Answer: A A. Fahrenheit B. Rankine C. Celsius D. Kelvin 7. Given steam pressure of 900 lb/ft2, temperature of 300oF, specific volume of 5.8 ft3/lb. If the specific enthalpy is 9500 ft-lb/lb, what is the internal energy per lb of the system? Answer: D A. 4400 B. 3900 C. 3600 D. 4280
8. The barometer reads 29.0 inches (737 mm) of mercury. What is the absolute pressure if a vaccum gage reads 9.5 psi (66 kpa) in SI? Answer: A A. 32.02 kpa B. 33.04 kpa C. 31.36 kpa D. 31.86 kpa 9. A fluid with a vapor pressure of 0.2 Pa and a specific gravity of 12 is used in a barometer. If the fluid column height is 1m, what is the atmospheric pressure? Answer: D A. 150.6 kpa B. 115.5 kpa C. 144.4 kpa D. 117.7 kpa 10. What is the atmospheric pressure on a planet if the pressure is 100 kpa and the gage pressure is 10 kpa? Answer: D A. 10 kpa B. 100 kpa C. 80 kpa D. 90 kpa 11. A column of water 200 cm high will give a pressure equivalent to: Answer: D A. 9810 dyne/cm2 B. 0.1 atm C. 0.10 bar D. 19,620 N/m2 12. What is the equivalent oR of 400ok? Answer: A A. 720.60oR B. 851.15oR C. 670.27oR D. 344.25oR 13. If the temperature inside the furnaces is 700 oK, what is the corresponding reading in oF? Answer: D A. 700.60 B. 750.60 C. 860.60 D. 800.60
14. If the oF scale is twice the oC scale, what will be the corresponding reading in each scale? Answer: B A. 22oC and 44oF B. 160oC and 320oF C. 40oC and 80oF D. 100oC and 200oF
15. Water enters the condenser at 25oC and leaves at 40oC. What temperature difference in oF? Answer: C A. 25 B. 26 C. 27 D. 28 16. Water enters the heater with 28oC and leaves at 75oC. What is the temperature change in oF? Answer: C A. 74.80 B. 38.29 C. 84.80 D. 57.36 17. The specific gravity of mercury relative to water is 13.55. What is the specific weight of mercury? The specific weight of water is 62.4 lb per cubic foot. Answer: B A. 102.3 KN/m3 B. 132.9 KN/m3 C. 150 KN/m3 D. 82.2 KN/m3 18. An iron block weighs 5 N and has a volume of 200 cm3. What is the density of the block? Answer: C A. 988 kg/m3 B. 1255 kg/m3 C. 2550 kg/m3 D. 800 kg/m3 19. The suction pressure of Answer: D A. B. C. D.
a pump reads 540 mmHg vaccum. What is the absolute pressure in kpa? 40 3.3 60 29.3
20. A boiler installed where the atmospheric pressure is 755 mmHg. Has a pressure 12 Kg/cm 2 . What is the absolute pressure in Mpa? Answer: B A. 1.350 B. 1.277 C. 1.200 D. 1,700 21. A storage tank contains oil with specific gravity of 0.88 and depth of 20 m. What is the hydrostatic pressure at the bottom of th tank in kg/cm2? Answer: A A. 1.76 B. 2.0 C. 6.0 D. 3.0 22. A batch of concrete consisted of 200 lbs fine aggregate, 350 lbs coarse aggregate, 94 lbs, cement, and 5 gallons water. The specific gravity of the sand and gravel may be taken as 2.65 and that of the cement as 3/10/ What was the weight of concrete in place per cubic foot? Answer: D
A. B. C. D.
172 lbs 236 lbs 162 lbs 153 lbs
23. A batch of concrete consisted of 200 lbs fine aggregate, 350 lbs coarse aggregate, 94 lbs, cement, and 5 gallons water. The specific gravity of the sand and gravel may be taken as 2.65 and that of the cement as 3.10. How much by weight of cement is required to produce one cubic yard? Answer: D A. 765 B. 657 C. 675 D. 567 24. A cylindrical tank 2 m diameter, 3 m high is full of oil. If specific gravity of oil is 0.9, what is the mass of oil in the tank? Answer: A A. 8482 kg B. 4500 kg C. 1800 kg D. 7000 kg 25. 100 g of water are mixed with 150 g of alcohol (w = 790 kg/m 3). What is the specific volume of the resulting mixtures, assuming the fluids mixed completely? Answer: D A. 0.82 cm3/kg B. 0.88 cm3/kg C. 0.63 cm3/kg D. 1.20 cm3/kg 26. 100 g of water are mixed with 150 g of alcohol (w = 790 kg/m 3). What is the specific gravity of the resulting mixtures, assuming the fluids mixed completely? Answer: D A. 0.96 B. 0.63 C. 0.82 D. 0.86 27. A spherical tank is full of water that has a total mass of 10,000 kg. If the outside diameter of the tank is 2722 mm, how thick is the wall of the tank? Answer: B A. 50 mm B. 25 mm C. 30 mm D. 35 mm 28. A cylindrical tank is filled with water at the rate of 5000 gal/min. The height if the water in the tank after minutes is 20.42 ft. What is the diameter of the tank? Answer: B A. 30 ft B. 25 ft C. 20 ft D. 9 m 29. Water is flowing through a 1 foot diameter pipe at the rate of 10 m/s. What is the volume flow of water flowing? Answer: C A. 7.50 ft3/sec
B. 7.95 ft3/sec C. 7.85 ft3/sec D. 0.22 ft3/sec 30. A certain fluid is flowing in a 0.5 m x 0.3 m channel at the rate of 3 m/sec and has a specific volume of 0.0012 m3/kg. Determine the mass of water flowing in kg/sec. Answer: C A. 380 kg/sec B. 390 kg/sec C. 375 kg/sec D. 370 kg/sec 31. One useful equation used is the change of enthalpy of compressible liquid with constant specific heat is: hsub2 - hsub1 = c(Tsub2 – Tsub1) + v(Psu2 – Psub1) where: Tsubn = Temperature at state n Psubn = Pressure at state n V = specific volume of liquid Water with enthalpy with csubp = 4.187 KJ/kg-oK and v = 1.00 x 10 -3 m3/kg has the following states: State I: Tsub1= 19oC Psub1 = 1. 013 x 105 o State II: Tsub2 = 30 C Psub2 = 0.113 Mpa What is the change in enthalpy from state I to state II? Answer: C A. 46.0 kpa/kg B. 56.0 KJ/kg C. 46.0 KJ/kg D. 46.0 KN/kg 32. What is the potential energy of a 500 kg body if it is dropped to a height of 100 m? Answer: A A. 490.50 KJ B. 765.50 KJ C. 560.50 KJ D. 645.48 KJ 33. The flow energy of 124 li/min of a fluid passing a boundary to a system is 2 KJ/sec. What is the pressure at this point. Answer: B A. 100 kpa B. 140.30 psi C. 1000 kpa D. 871 KJ 34. Steam at 1000 lb/ft3 pressure and 330oR has a specific volume of 6.5 ft 3/lb and a specific enthalpy of 9800 ft-lb/lb. Find the internal energy per pound mass of steam. Answer: B A. 5400 B. 3300 C. 6400 D. 2500
35. Air and fuel enter a furnace used for home heating. The air has an enthalpy of 302 KJ//kg and the fuel has an enthalpy of 43,207 KJ/kg. The gases leaving the furnace have an enthalpy of 616 KJ/kg. of fuel. The house requires 17.6 KW of heat. What is the fuel consumption per day? Answer: B A. 85 kg B. 41 kg C. 45 kg D. 68 kg 36. The power plant furnace burns coal at the rate of 108,200 kg/hr. Air at 100.8 kpa, 28 oC is supplied at the rate of 13.8 kg/kg coal. Determine the volume flow rate of air flow in m 3/min. Answer: A A. 21,327 m3/min B. 19,414.63 m3/min C. 20,435.26 m3/min D. 24,535.54 m3/min 37. The enthalpy of air is increased by 139.586 KJ/kg in a compressor. The rate of air flow is 16.42 kg/min. The power output is 48.2 KW. Which of the following values most nearly equals the heat loss from the compressor in KW? Answer: A A. -10 B. +10.2 C. -9.95 D. +9.95 38. A steam turbine receives 70 pounds of steam per minute with an enthalpy of 1600 Btu per pound and velocity of 100 ft/sec. It leaves the turbine at 900 ft/sec and 1320 Btu/lb enthalpy. The radiation loss is 84,000 Btu/hr. Find the horsepower output. Answer: A A. 403 hp B. 400hp C. 380 hp D. 410 hp 39. Steam enters a turbine stage with enthalpy of 3628 KJ/kg 70 m/sec and leaves the same stage with an enthalpy of 2846 KJ/kg and a velocity of 124 m/sec. Calculate the work done by the steam. Answer: A A. 776.76 KJ/kg B. 873 KJ/kg C. 567.23 KJ/kg D. 923.34 KJ/kg
40. Steam with an enthalpy of 800 kcal/kg enters a nozzle at a velocity of 80 m/sec. Find the velocity of the steam at the exit of the nozzle if its enthalpy is reduced tp 750 kcal/kg. assuming the nozzle is horizontal and disregarding heat losses. Take g(9.81) m/sec and J = 427 kg-m/kcal. Answer: D
A. B. C. D.
561.24 m/s 142.5 m/s 52.41 m/s 652.14 m/s
41. A volume of 450 cc of air is measured at a pressure of 740 mm HG absolute and a temperature of 20oC. What is the volume in cc at 760 mm HG abs. and 0 oC? Answer:B A. 516.12 B. 408.25 C. 620.76 D. 375.85 42. Assuming compression is according to the law PV = constant. Calculate the initial volume of gas at a pressure of 2 bar which will occupy a volume of 6 cubic meters when it is compressed to a pressure of 42 bar. Answer: A A. 126 m3 B. 120 m3 C. 130 m3 D. 136 m3 43. How much heat, KJ must be transferred to 20kg of air to increase the temperature from 20 degrees C to 280 degrees C if the pressure is maintained constant. Answer: C A. 2500 B. 2050 C. 5200 D. 5500 44. If air is at pressure, p, volume , v? Answer: B A. B. C. D.
of 3200 lb/ft 2. And at a temperature, T, of 800 oR, what is the specific 14.2 ft3/lb 13.3 ft3/lb 11.2 ft3/lb 9.8 ft3/lb
45. The mass of air in the room 3m x 5m x 20m is known to be 350 kg. Find its density. Answer: C A. 1.617 kg/m3 B. 1.716 kg/m3 C. 1.167 kg/m3 D. 1.176 kg/m3 46. A transportation company specializes in the shipment of pressurized gaseous materials. An order is received for 100 liters of a particular gas at STP (32 oF and 1 atm). What minimum volume tank is necessary to transport the gas at 80oF and a maximum pressure of 8 atm? Answer: B A. 16 liters B. 14 liters C. 10 liters D. 12 liters 47. A bicycle has a volume of 600 cm3. It is inflated with carbon dioxide to pressure of 80 psi at 20 o C. How many grams of carbon dioxide are contained in the fire? Answer: A A. 5.98 g
B. 6.43 g C. 4.63 g D. 3.83 g 48. An ideal gas at 0.60 atm. And 87oC occupies 0.450 liters. How many moles are in the sample? (R = 0.0821 atm/mole K) Answer: D A. 0.0002 mole B. 0.0378 mole C. 0.0198 mole D. 0.0091 mole 49. Air compressed in a diesel engine from an initial pressure of 13 psia and a temperature of 120 oF to one twelfth of its original volume. Calculate the final temperature assuming compression to be adiabatic. Answer: D A. 987 B. 980 C. 981 D. 1107 50. The compression ratio of an Otto cycle is 6:1, P sub1 is 14.7 psia, Tsub1 is 68oF. Find the pressure and temperature at state 2. Answer: D A. 180.6 psia, 1081oF B. 180.6 psia, 139 oF C. 180.6 psia, 139 oF D. 180.6 psig, 1081oR 51. An automobile tire is inflated to 30 psig pressure at 50 oF. After being driven, the temperature rise to 75oF. Determine the final gage pressure assuming the volume remains constant. Answer:A A. 32.19 psig B. 55 psig C. 0 psig D. 38.9 psig 52. If 10 m3 of atmospheric air at zero degrees centigrade temperature are compressed to a volume of 1 m3 at 100oC, what will be the pressure of air in kpa? Answer: B A. 1500 B. 1384 C. 2000 D. 1000 53. If 8 lbs of a substance receives 240 Btu of heat at constant colume and undergo a tempearure change of 150oF/ What is the average specific heat of the substance during the process? Answer: D A. 0.30 Btu/lb-oF B. 0.25 Btu/lb-oF C. 0.50 Btu/lb-oF D. 0.20 Btu/lb-oF 54. A certain gas at 101.325 kpa and 16 oC whose volume is 2.83 m3 are compressed into a storage vessel of 0.31 m3 capacity. Before admission, the storage vessel contained the gas at a pressure
and temperature at 137.8 kpa and 24 oC; after temperature of the gas in the vessel in Kelvin? Answer: B A. 298.0 B. 319.8 C. 180.0 D. 420.0 55. The temperature of an ideal gas remains constant while the absolute pressure changes from 103.4 kpa to 827.2 kpa. If the initial volume is 80 liters, what is the final volume? Answer:B A. 100 li B. 10 li C. 8 li D. 1000 li 56. What is the density of air under standard condition: Answer: C A. 1.1 kg/m3 B. 1 kg/m3 C. 1.2 kg/m3 D. 1 KN/m3 57. What is the specific volume of an air at 30oC and 150 kpa? Answer: D A. 1 m3/kg B. 0.5 m3/kg C. 1.2 m3/kg D. 0.579 m3/kg 58. The compression ratio of an Otto cycle is 5. If the initial pressure is 100 kpa, determine the final pressure. Answer: B A. 1000 kpa B. 952 kpa C. 300 kpa D. 100 kpa 59. How much work is done when 20 ft3 of an air is initially at a pressure of 15 psia and a temperature of 40oF experience an increase of pressure to 80 psi while volume remains constant? Answer: C A. 1000 Btu B. 3000 Btu C. Zero D. 2000 Btu 60. A perfect gas has a value of R = 58.8 ft-lb/lb- oR and k = 1.26. Btu are added to 5 lbs of this gas at constant volume when initial temperature is 90oF, find the initial temperature. Answer: B A. 100oF B. 104 oF C. 154 oF D. 185 oF 61. While the pressure remains constant and 689.5 kpa, the volume of air changes from 0.567 m 3 to 0.283 m3. What is the work done?Answer: A A. -196 KJ
B. 204 KJ C. 206 KJ D. -406 KJ 62. During the polytropic process of an ideal gas, the state changes from 20 psia and 40 oF to 120 psia and 340oF. Determine the value of n. Answer: C A. 1.233 B. 1.255 C. 1.355 D. 1.400 63. A group of 50 persons attend a secret meeting in a room which is 12 meters wide by 10 meters long and a ceiling height of 3 m. The room is completely sealed off and insulated. Each person gives off 120 kcal per hour of heat and occupies a volume of 0.2 m 3. The room has an initial pressure of 101.3 kpa and temperature of 16oC. Calculate the room temperature after 10 minutes. Answer: B A. 36.35 B. 33.10 C. 23.24 D. 76.32 64. The compression ratio of an ideal Otto cycle is 6:1. Initial conditions are 101.3 kpa and 20 oC. Find the pressure and temperature at the end of adiabatic compression. Answer: A A. 1244.5 kpa, 599.96oK B. 1244.5 kpa, gage, 60oC C. 1244.5 kpa, 60oC D. 1244.5 kpa, 599.96oC 65. Ammonia weighing 22 kgs is confirmed inside a cylinder equipped with a piston has an initial pressure of 413 kpa and 38oC. If 2900 KJ if heat is added to the ammonia until its final pressure and temperature are 413 kpa and 100 oC, respectively, what is the amount of work done bt rhe fluid in KJ? Answer: A A. 667 B. 304 C. 420 D. 502 66. Determine the average Cp value in KJ/kg-K of a gas of 522 KJ/kg of heat is necessary to raise the temperature from 300oK to 800oK making the pressure constant: Answer: B A. 1.440 B. 1.044 C. 1.038 D. 1.026
67. A tank contains 80 ft3 of air at a pressure of 350 psi; if the air is cooled until its pressure and temperature decreases to 200 psi and 70 oF respectively, what is the decrease in internal energy? Answer: B
A. B. C. D.
+4575 -5544 5552 0
68. If 10 lbs of water are evaporated at atmospheric pressure until a volume of 288.5 ft 3 is computed , how much work is done? Answer: C A. 1680 Btu B. No work C. 610000 ft-lb D. 550000 ft-lb 69. A large mining company was provided with a 3 m 3 of compressed air tank. Air pressure in the tank drops from 700 kpa to 180 kpa while the temperature remains constant at 28 oC. What percentage has the mass of air in the tank been reduced? Answer: A A. 74 B. 72 C. 76 D. 78 70. In a diesel cycle, the air compressed to one-tenth of its original volume. If the initial temperature of the air is 27oC, what is the final temperature? Answer: D A. 420oC B. 440 oC C. 460 oC D. 480 oC 71. Determine the vacuum efficiency of a surface condenser which operates at a vacuum of 635 mm Hg and exhaust steam enters the condenser at 45.81o. The barometric is 760 mm Hg. Answer: C A. 80.4 % B. 85.2% C. 92.2% D. 98.3% 72. A 4 m3/hr pump delivers water to a pressure tank. At the start, the gage reads 138 kpa until in reads 276 kpa and then the pump was shut off. The volume of the tank is 150 liters. At 276 kpa the water occupied 2/3 of the tank volume. Determine the volume of water that can be taken out unitl the gage reads 138 kpa. Answer: D A. 31.20 liters B. 65.32 liters C. 16.87 liters D. 29.50 liters
73. How much work is necessary to compress air in an insulated cylinder from 0.20 m 3 to 0.01 m3. Use T = 20oC and P1 = 100 kpa. Answer: D A. 113.4 KJ B. 121.4 KJ
C. 110.1 KJ D. 115.6 KJ 74. A gas initially 103.4 kpa and 0.0566 m 3 undergoes a process to 620.36 kpa and 0.017 m 3 during which the enthalpy increases by 16.35 KJ, C v = 10.217 KJ/kgoK. Determine the Cp of gas. Answer: A A. 14.33 KJ/kg-oK B. 2.34 Btu/lb-oR C. 13.23 KJ/kg-oK D. 10.76 Btu/lb-oK 75. A perfect gas has a value of R = 5808 ft-lb/lb- oR and k = 1.26. If 20 Btu are added to 5 lb of this gas at constant volume when initial temperature is 90oF, find the final temperature. Answer: C A. 100.76oC B. 167.76 oC C. 103.76 oC D. 145.76 oC 76. While the pressure remains constant at 689.5 kpa the volume of a system of air changes from 0.567 m3 to 0.283 m3. Find the change of internal energy. Answer: B A. 389.68 KJ B. 493.63 KJ C. 678.68 KJ D. 245.68 KJ 77. If initial volume of an ideal gas is compressed to one half its original volume and to twice its original temperature, the pressure. Answer: B A. Doubles B. Quadruples C. Remains constant D. Halves 78. What horsepower is required to isothermally compress 800 ft 3 of air per minute from 14.7 psia to 120 psia? Answer: D A. 13900 Hp B. 28 Hp C. 256 Hp D. 108 Hp 79. An ideal gas at 45 psig and 80oF is heated in a closed container to 130 oF. What is the final pressure?Answer 80. A Carnot engine requires 35 KJ/sec from the hot source. The engine produces 15 kw of power ant the temperature of the sink 26oC. What is the temperature of the hot source? Answer C A. 245.57 B. 210.10 C. 250.18 D. 260.68 81. A Carnot engine receives 130 Btu of heat from a hot reservoir at 700 oF and rejects 49 Btu of heat. Calculate the temperature of the cold reservoir. Answer: D A. -21.9oF
B. -24.2 oF C. -20.8 oF D. -22.7 oF 82. The maximum thermal 225 oF is: A. B. C. D.
efficiency possible for a power cycle operating between 1200 oF and 58% 58.73% 57.54% 57.40%
83. A heat engine is operated between temperature limits of 1370 oC and 260oC. Engine supplies with 14,142 KJ per KWH. Find the Carnot cycle efficiency in percent.Answer: C A. 70.10 B. 65.05 C. 67.56 D. 69.32 84. An Otto cycle has clearance volume of 7%. It produces 300 kw power. What is the amount of heat rejected in KW? Answer: C A. 170 B. 160 C. 152 D. 145 85. A closed vessel contains air at a pressure of 160 KN/m 2 gauge and temperature of 30oC. The air is heated at constant volume of 60oC with the atmospheric pressure as 759 mm Hg. What is the final gauge pressure? Answer: C A. 174 B. 169 C. 185.8 D. 172 86. An air standard engine has a compression ratio of 20 and cut-off ratio of 5. If the intake air pressure and temperature are 100 kpa and 27oC, find the work in KJ per kg. Answer: B A. 2976 B. 2166 C. 2437 D. 2751 87. The thermal efficiency of a particular engine operating on an ideal cycle is 35%. Calculate the heat supplied per 1200 watt-hr of work developed in KJ. Answer:A A. 12343 B. 10216 C. 14218 D. 11108 88. In an air standard Otto cycle, the clearance volume is 18% of the displacement volume. Find the compression ratio and or thermal efficiency. Answer: C A. 0.52 B. 0.53
C. 0.55 D. 0.60 89. The clearance of a diesel cycle is 1.0%. If initial temperature is 27 oC, determine the final temperature. Answer: A A. 510oC B. 610 oC C. 540 oC D. 1000 oC 90. For an ideal cycle with overall value of k = 1.33, compression ratio is 15 and cur-off ratio of 2.1, determine the cycle efficiency.Answer: B A. 50.62% B. 52.90% C. 46% D. 49% 91. An ideal Otto cycle with 15% clearance operates on 0.227 kg/sec of air with k = 1.32. Determine the efficiency of the cycle. Answer: D A. 50.65% B. 43.84% C. 41.32% D. 47.89% 92. An ideal Otto cycle, operating in hot air with k = 1.34 has compression ratio of 5. Determine the efficiency of the cycle. Answer: A A. 42.14% B. 62.27% C. 64.27% D. 36.46% 93. An engine operates on the air standard Otto cycle. The cycle work is 900 KJ/kg, the maximum cycle temperature at the end of isentropic compression is 600 oC. Determine the engines compression ratio. Answer: A A. 6.388 B. 10.45 C. 8.67 D. 7.87 94. In an air standard diesel cycle, compression start at 100 kpa and 300 oK. The compression ratio is 16 to 1. The maximum cycle temperature is 2031oK. Determine the cycle efficiency. Answer: C A. 60.34% B. 56.23% C. 65.98% D. 45.45% 95. A diesel engine is operating on a 4-stroke cycle, has a heat rate of 11315.6 KJ/KW-hr brake. The compression ratio is 13. The cut-off ratio is 2. Using k = 1.32, what is the brake engine efficiency. Answer: A A. 63.5% B. 51.2% C. 73.5%
D. 45.3% 96. Determine the air-standard efficiency of an engine operating on the diesel cycle with clearance of 8% when the suction pressure is 99.97 kpa and the fuel is injected for 6% of the stroke. Assume k = 1.4. Answer: D A. 63.5% B. 51.2% C. 73.5% D. 60.02% 97. A heat engine ( Carnot cycle ) has its intake and exhaust temperature if 157 oC and 100oC, respectively. What is its efficiency? Answer: D A. 12.65% B. 14.75% C. 15.35% D. 13.25% 98. Find the enthalpy of 100 psi and 97% quality, hf = 298.55 Btu/lb; hfg = 889.119 Btu/lb. Answer: B A. 1170 Btu/lb B. 1161 Btu/lb C. 1734 Btu/lb D. 1803 Btu/lb 99. 180 grams of saturated water of temperature 95 oC undergoes evaporation process until all vapor completely vaporized. Determine the changed in volume. At 95 oC, vf= 0.0010397 m3/kg. Answer: D A. 0.1656 m3 B. 0.4235 m3 C. 0.2565 m3 D. 0.3656 m3 100. Five kilograms of saturated liquid at kpa is heated until its moisture content is 5%. Find the work done for this process. Answer A A. 813.59 KJ/kg B. 643.23 KJ/kg C. 542.34 KJ/kg D. 753.12 KJ/kg 101. Twenty kilograms of water at 40 oC is confined in a rigid vessel. The heat is supplied until all the water is completely vaporized. Find the heat added in KJ. Answer: C A. 45,422 KJ B. 43,122 KJ C. 45,252 KJ D. 65,233 KJ 102. Steam at 2 Mpa and 250oC in a rigid cylinder is cooled until the quality is 50%. Find the heat rejected from the cylinder. At 2 Mpa and 250oC V = 0.11144 m3/kg u = 2679.6 KJ/kg At 2 Mpa, (saturated)
Vf = 0.0011767 m3/kg vg = 0.09963 m3/kg A. -432.23 KJ/kg B. -926.26 KJ/kg C. -834.55 KJ/kg D. 1082.34 KJ/kg
uf = 906.44
1693.8 Answer: B
103. At 1.3 Find the entropy in KJ/kg-K at 90% moisture of a 1 Mpa steam-water mixture? At 1 Mpa: sg = 6.5865 sfg = 4.4478 A. 4.87 B. 6.34 C. 2.583 D. 4.36 104. At 1.3 Mpa, mixture steam and water has an entropy of 4 KJ/kg-K. Find the enthalpy of the mixture. At 1.3 Mpa: sf = 2.2515, sg = 6.4953, hf = 514.93, hfg = 1972.7 Answer: A A. 1627.71 KJ/kg B. 1533.33 KJ/kg C. 1234.45 KJ/kg D. 1734.45 KJ/kg 105. Mixture with 80% quality at 500 kpa is heated isothermally until its pressure is 300 kpa. Find the heat added during the process. At 500 kpa: sf = 1.8607, sfg = 4.9606 At 300 kpa and 151.86oC: s = 7.0888 KJ/kg Answer: B A. 652.34 KJ/kg B. 535.16 KJ/kg C. 983.44 KJ/kg D. 765.34 KJ/kg 106. A tank contains exactly one kilogram of water consisting of liquid and vapor in equilibrium at 1 Mpa. If the liquid and vapor each occupy one-half the volume of the tank, what is the enthalpy of the content of the tank? Answer: B A. 644.40 KJ/kg B. 774.40 KJ/kg C. 833.40 KJ/kg D. 435.29 KJ/kg 107. A vessel with a volume of 1 m3 contains liquid water and water vapor in equilibrium at 600 Kpa. The liquid water has a mass of 1 kg. Using steam tables, calculate the mass of water vapor. Answer: A A. 3.16 kg B. 0.99 kg C. 1.57 kg D. 1.89 kg 108. Water substance at 70 bar and 65oC enters a boiler tube of constant inside diameter of 25 mm. The water leaves the boiler tube at 50 bar and 700 oK at velocity of 100 m/s. Calculate the inlet velocity(m/sec) Answer: C A. 1.56 B. 2.12
C. 1.672 D. 3.230 109. Water substance at 70 bar and 65 oC enters a boiler tube of constant inside diameter of 25 mm. The water leaves the boiler tube at 50 bar and 700 oK at velocity of 100 m/s. Calculate the inlet volume of 100 m/s. Calculate the inlet volume flow (li/sec) Answer: A A. 0.821 B. 1.561 C. 0.344 D. 2.133 110. One lb (0.455kg) of a mixture of steam and water at 160 psia(1103.2 kpa) is in rigid vessel. Heat is added to the vessel until the content are at 560 psia (3861.2 kpa) and 600 oF (315.55oC). Determine the quantityof heat in KJ added to the water and steam in the tank. Answer: A A. 1423.70 B. 1392.34 C. 1562.34 D. 1294.45 111. Steam at the rate of 600 kg/hr is produced by a steady flow system boiler from feedwater entering at 40oC. Find the rate at which heat is transformed in Kcal per hour if enthalpy of steam is 660 Kcal/kg and of the feedwater at 40 Kcal/kg. Answer: A A. 372000 B. 387000 C. 345200 D. 312444 112. Steam leaves and industrial boiler at 827.4 kpa and 171.6 oC. A portion of the steam is passed through a throttling calorimeter and is exhausted to the atmosphere when the calorimeter pressure is 101.4 kpa. How much moisture does the steam leaving the boiler contain if the temperature is 115.6oC? Answer: B A. 3.78% B. 3.08% C. 4.56% D. 2.34%
113. Steam enters a throttling calorimeter at a pressure of 1.03 Mpa. The calorimeter downstream pressure and temperature are respectively 0.100 Mpa and 125 oC. What is the percentage moisture if the supply steam? Properties of steam: P, Mpa hf hfg hg 1.03 2010.7 2779.25 Note: @ 0.1.. Mpa and 125oC: h = 2726.6 KJ/kg. Answer: A
A. 2.62 B. 5.21 C. 3.15 D. 1.98 114. A vessel of 0.058 m3 capacity is well insulated and is divided equally by a rigid conducting diaphragm. Initially both halves contain air at pressure of 137.8 kpa and 413.4 kpa and temperature 27oC and 177oC respectively. What is the increase of entropy of the system in KJ/ oC? Answer: C A. 1.002 B. 0.5080 C. 0.00173 D. 0.1080 115. Using steam table. Find the enthalpy of steam at kpa if its specific volume is 0.3598 m 3/kg. Answer: A A. 1625.86 KJ/kg B. 1785.34 KJ/kg C. 1543.45 KJ/kg D. 1687.55 KJ/kg 116. A throttling calorimeter is connected to the desuoerheated steam line supplying steam to the auxiliary feed pump on a ship. The line pressure measures 2.5 Mpa. The calorimeter pressure of 137.8 kpa and 413.4 kpa and temperature of 27oC and 177oC respectively. What is the increase of entropy of the system in KJ/oC? Answer: C A. 6.8 KJ/kg-oK B. 7.2 KJ/kg-oK C. 6.6 KJ/kg-oK D. 7.5 KJ/kg-oK 117. Steam enters an isothermal compressor at 400 oC and 100 kpa. The exit pressure is 10 Mpa, determine the change of enthalpy. Answer: D A. 198 KJ/kg B. 178 KJ/kg C. 187 KJ/kg D. 182 KJ/kg 118. Steam enters an adiabatic at 300 oC and 400 kpa. It exits as a saturated vapor at 30 kpa. Determine the work done. Answer: B A. 476.34 KJ/kg B. 441.50 KJ/kg C. 436.33 KJ/kg D. 524.34 KJ/kg 119. A 0.5 m3 tank contains saturated steam at 300 kpa. Heat is transferred until pressure reaches 100 kpa. Find the final temperature.Answer: C A. 94.45oC B. 83.23oC C. 99.63oC D. 103.2oC
120. A 500 li contains a saturated mixture of steam and water at 300 oC. Determine the mass of vapor if their volumes are equal. Answer: A A. 11.54 kg B. 10.34 kg C. 13.45 kg D. 16.34 kg 121. A 1 kg steam-water mixture at 1.0 Mpa is contained in an inflexible tank. Heat is added until the pressure rises to 3.5 Mpa and 400oC. Determine the heat added. Answer: A A. 1378.64 KJ B. 1532.56 KJ C. 1456.78 KJ D. 1635.45 KJ 122. Atmospheric pressure boils at 212 oF. At the vacuum pressure at 24 in Hg, the temperature is 142oF. Find the boiling temperature when the pressure is increased by 45 psia. Answer: C A. 342.34oF B. 526.34oF C. 479.13oF D. 263.45oF 123. What is the temperature in degree C of 2 liters of water at 30 oC after 500 calories of heat have been added to? Answer: B A. 35.70 B. 30.25 C. 38.00 D. 39.75 124. A mass of 0.36 kg metal having a temperature of 100 oC is plunged into 0.04 kg if water at 20 oC. The temperature of the water and metal becomes 48 oC. The latent heat of ice at 0oC is 335 KJ.kgo K, Assuming no heat loss to the surroundings, determine the specific heat capacity of the metal in KJ/kg-oK. Answer: D A. 0.234 B. 0.564 C. 0.754 D. 0.451 125. What is the total energy required heating in raising the temperature of a given amount of water when the energy applied is 1000 KWH with heat losses of 25%? Answer: C A. 1000 B. 1500 C. 1333 D. 1250 126. A 30 kg iron was put in a container with 14.33 kg water. The water is at 10 oC and the iron has an initial temperature of 439oK until the iron was in thermal equilibrium with water. Find the change in entropy. (Cp = 0.4 KJ/kgoK) Answer: D A. -12.56 KJ/oK B. -43.58 KJ/oK C. -25.78 KJ/oK D. -6.6 KJ/oK
FUELS & COMBUSTION 1. A diesel power plant consumes 650 liters of fuel at 26 oC in 24 hours with 28 oAPI. Find the fuel rate in kg/hr. Answer: A A. 23.83 B. 24.85 C. 22.85 D. 26.85 2. A boiler burns fuel oil with 15% excess air. The fuel oil may be represented by C 14H34. Calculate the molal air fuel ratio. Answer: B A. 14 B. 117.69 C. 102.34 D. 17.14
3. A diesel power plant uses fuel that has a density of 892.74 kg/m 3 at 15.67oC. Find the heating value of fuel. Answer: A A. 44,900 KJ/kg B. 19,301 Btu/lb C. 43,000 KJ/kg D. 4356.2 KJ/kg 4. A certain coal has the following ultimate analysis: C = 69% N2 = 5% H2 = 2.5% S = 7% Moisture = 8% O2 = 3.5% Ash = 5% Determine the heating value of fuel used.Answer: A A. 26,961.45 KJ/kg B. 45,256 KJ/kg C. 25,002.4 KJ/kg D. 26,000 KJ/kg 5. A diesel power plant uses fuel with heating value of 45,038.8 KJ/kg. What is the density of fuel used at 30°C?Answer: D A. 0.900 kg/li B. 0.887 kg/li C. 0.850 kg/li D. 0.878 kg/li 6. A diesel engine consumed 945 liter of fuel per day at 30°C. If the fuel was purchased at 15.5°C and 30° API at P5.00/li, determined the cost of fuel to operate the engine per day. Answer: B A. P5677.50 B. P4677.50 C. P4888.90 D. P5000.00
7. A cylindrical tank 3 m long and 2 m diameter is used for oil storage. How many days can the tank supply the engine having 27° API with fuel consumption of 60 kg/hr. Answer: B A. 4.84 B. 5.84 C. 7.84 D. 8.84 8. Determine the minimum volume of day tank in m 3 of 28° API fuel having a fuel consumption of 200 kg/hr. Answer: B A. 10.43 m3 B. 5.41 m3 C. 6.87 m3 D. 7.56 m3 9. Given the following ultimate analysis: C = 70% O2 = 4% N2 = 5% S2 = 6% Moisture = 8% H2 = 3% Ash = 5% Using 25% excess air, determine the actual air fuel ratio. Answer: A A. 11.46 B. 24.85 C. 23.85 D. 26.85 10. A 650 Bhp diesel engine uses fuel oil of 28° API gravity, fuel consumption is 0.65 lb/Bhp-hr. Cost of fuel is P7.95 per liter. For continuous operation, determine the minimum volume of cubical day tank in cm3, ambient temperature is 45°C. Answer: A A. 5,291,880 cm3 B. 5,391,880 cm3 C. 5,491,880 cm3 D. 5,591,880 cm3 11. A 650 Bhp diesel engine uses fuel oil of 28° API gravity, fuel consumption is 0.65lb/Bhp-hr. Cost of fuel is P7.95 per liter. For continuous operation, determine the cost of fuel per day at 45°C. Answer: B A. P42,870.45 B. P42,070.45 C. P42,570.45 D. P42,170.45
12. A logging firm in Isabela operates a Diesel Electric Plant to supply its electric energy requirements. During a 24 hour period, the plant consumed 250 gallons of fuel at 80°F and produced 2700 KW-Hrs. Industrial fuel used is 30° API and was purchased at P3.00li/at 60°F. Determine cost of fuel to produce one Kwh. Answer: C A. P3,043/KW-h B. P4,043/KW-h C. P1,043/KW-h D. P2,043/KW-h
13. A logging firm in Isabela operates a Diesel Electric Plant to supply its electric energy requirements. During a 24 hour period, the plant consumed 250 gallons of fuel at 80°F and produced 2700 KW-hrs. Industrial fuel used is 30° API and was purchased at P3.00/li at 60°F. Determine the overall thermal efficiency of the plant. Answer: A A. 26.08% B. 43.23% C. 43.12% D. 18.46% 14. A diesel electric plant in one of the remote provinces in the south utilized diesel fuel with an °API of 28 at 15.6°C. The plant consumes 680 liters of diesel fuel at 26.6°C in 24 hrs, while the power generated for the same period amounts to 1,980KW-hrs. Determine overall thermal efficiency of the plant. Answer: A A. 26.47% B. 12.34% C. 23.45% D. 34.34% 15. A circular fuel tank 45 feet long and 5.5 feet diameter is used for oil storage. Calculate the number of days the supply tank can hold for continuous operation the following conditions: Steam flow = 2000 lbs/hr Steam dry and saturated at 200 psia Feedwater temperature = 230°F Boiler Efficiency = 75% Fuel oil = 34° API Answer: B A. 12.34 B. 17.58 C. 13.45 D. 23.44 16. A steam generator burns fuel oil with 20% excess air. The fuel oil may be represented by C 14 H30. The fuel gas leaves the preheater at 0.31 Mpa. Determine the actual air-fuel ratio in kg air per kg fuel. Answer: A A. 17.89 B. 15.67 C. 12.34 D. 19.45
17. A steam generation burns fuel oil with 20% excess air. The fuel oil may be represented by C 14H30. The fuel gases leave the preheater at 0.31 Mpa. Determine partial pressure of H 2O. Answer: C A. 23.34 kpa B. 29.34 kpa C. 35.7 kpa D. 32.34 kpa
18. In the boiler design, it is desired to have the flue gas exit temperature above the dew point. Estimate the dew point temperature of the flue gas produced by combustion having the gravimetric analysis of: Answer: D N2 = 71.84% CO2 = 20.35% O2 = 3.61% H2O = 4.20% A. 32°C B. 23°C C. 45°C D. 39°C 19. A flue gas has following volumetric analysis: CH4 = 68% C2H6 = 32% Assume a complete combustion with 15% excess air at 101.325 Kpa, what is the partial pressure of water vapor in Kpa. Answer: A A. 15.95 B. 23.12 C. 12.45 D. 27.34 20. The dry exhaust gas from oil engine has the following gravimetric analysis: CO2 = 21.6% O2 = 4.2% N2 = 74.2% Specific heat at constant pressure for each components of the exhaust gas in Kcal/kg °C are: CO2 = 0.203 O2 = 0.219 N2 = 0.248 Calculate the gas constant in J/kg°K.Answer: A A. 272 C. 274 B. 276 D. 278 21. The dry exhaust gas from oil engine has the following gravimetric analysis: CO2 = 21.6% O2 = 4.2% N2 = 74.2% Specific heat at constant pressure for each component of the exhaust gas in Kcal/kg °C are: CO2 = 0.203 O2 = 0.219 N2 = 0.248 Calculate the specific gravity if the molecular weight of air is 28.97 kg/kg-mol. Answer: C A. 0.981 B. 1.244 C. 1.055 D. 0.542
22. The dry gas from oil engine has the following gravimetric analysis: CO2 = 21.6% O2 = 4.2% N2 = 74.2% Specific heat at constant pressure for each component of the exhaust gas in Kcal/kg °C are: CO2 = 0.203 O2 = 0.219 N2 = 0.248 Calculate the specific heat for the gas in KJ/kg - °K. Answer: B A. 0.872 B. 0.992 C. 0.452
D. 0.673 23. A bituminous coal has the following composition: C = 71.5% H = 5.0% O = 7.0% N = 1.3 S = 3.6% Ash = 8.2% W = 3.4% Determine the theoretical weight of Oxygen in lb/lb of coal. Answer: C A. 2.870 B. 3.120 C. 2.274 D. 6.233 24. There are 20 kg of flue gases formed per kg of fuel oil burned in the combustion of a fuel oil C12H26. What is the excess air in percent?Answer: A A. 26.67% B. 18.34% C. 12.34% D. 20.45% 25. A gaseous fuel mixture has a molal analysis: H2 = 14% CH4 = 3% CO = 27% O2 = 0.6% CO2 = 4.5% N2 = 50.9% Determine the air-fuel ratio for complete combustion on molal basis.Answer: C A. 2.130 B. 3.230 C. 1.233 D. 1.130 26. A steam generation burns fuel oil that has the following chemical analysis by mass in percent: Answer: C C = 85.3 H2 = 14.1 S = 0.5 N2 = 0.1 A. 19.85 C. 17.93 B. 11.14 D. 14.20 27. Calculate the theoretical air needed for the complete combustion of ethane C 2H6 for 20 kg fuel. Answer: D A. 432.23 kg B. 287.45 kg C. 234.45 kg D. 320.32 kg 28. A fuel oil burned with 50 percent excess air, and the combustion characteristics of the fuel oil are similar to C12H26. Determine the volumetric (molal) analysis of CO2 in the production of combustion. Answer: B A. 9.34% B. 8.66% C. 6.34% D. 7.45% 29. Fuel oil, C12H26 is burned in air at atmospheric pressure. The Orsat analysis of the products of combustion yields.
CO2 : 12.8% O2 : 3.5% CO : 0.2% N2 : 83.5% Determine the percent excess air. Answer: C A. 12.34% B. 8.34% C. 10.52% D. 18.45% 30. An unknown fuel has the following Orsat analysis: CO2 : 12.5 CO : 0.3% O2 : 3.1% N2 : 84.1% Determine the actual air – fuel in kg air per kg fuel. Answer: A A. 17.13 B. 12.34 C. 19.23 D. 23.23 31. What mass of liquid oxygen is required to completely burned 1000kg of liquid butane, C 4H10 on a rocket ship? Answer: C A. 4568 B. 2746 C. 3586 D. 6345 32. A volumetric analysis of a gas mixture is as follows: CO2 : 12.5% O2 : 4% N2 : 82% CO : 2% What is the percentage of CO on a mass basis? Answer: D A. 1.0% B. 1.5% C. 1.2% D. 1.9% 33. What is the percent theoretical air for a combustion process to which the fuel and combustion gas analysis are known as follows:Answer: A Fuel: % by volume CO2 : 12.4% CO : 27% H2 : 2.2% N2 : 58.4% Combustion gas: % by volume CO2 : 24.6% O2 : 1.0%
A. B. C. D.
H2 111 C.116 121 D.126
: 74.4%
VARIABLE LOAD 1. A 50 MW power plant has an average load of 31,500 KW and a factor of 70%. Find the reserve over peak. Answer: C A. 4 MW B. 3 MW C. 5 MW D. 6 MW 2. The daily energy produced in a certain power is 280,000 KW – hrs. What is the daily average load? Answer: D A. 10 MW B. 15 MW C. 25 MW D. 20 MW 3. The annual energy produced in a 100 MW power plant is 438,000,000 KW – hrs. What is the annual capacity factor of the plant? Answer: B A. 40% B. 50% C. 35% D. 60% 4. A power plant has a use factor of 50% and factor of 44%. How many hours did it operate during the year? Answer: C A. 7700 hrs. B. 7800 hrs. C. 7709 hrs. D. 7805 hrs.
STEAM CYCLE 1. In a Rankine cycle steam enters the turbine at 2.5 Mpa (enthalpies & entropies given) and condenser of 50 Kpa (properties given), what is the thermal efficiency of the cycle. Answer A At 2.5 Mpa: hg = 2803.1 KJ/kg sg = 6.2575 At 50 kpa: sf = 1.0910 sfg = 6.5029 hf = 340.49 hfg = 2305.4 vf = 0.0010300 A. 25.55% B. 45.23%
C. 34.23% D. 12.34% 2. In an ideal Rankine cycle, the steam throttle condition is 4.10 Mpa and 440 0C. If turbine exhaust is 0.105 Mpa, determine the pump work in Kj per kg. Answer C A. 6.34 B. 5.34 C. 4.17 D. 2.12 3. A thermal power plant generates 5 MW has also 300 OW power needed for auxiliaries. If the heat generated by fuel is 13,000 KJ/sec, determine the net thermal efficiency. Answer B A. 35.78% B. 36.15% C. 30.56% D. 33.67 4. In an ideal Rankine cycle, the steam throttle condition is 4.10 Mpa and 440 0C. If turbine exhaust is 0.105 Mpa, determine the thermal efficiency of the cycle. Answer B A. 20.34% B. 27.55% C. 34.44% D. 43.12% 5. In a Rankine cycle, saturated liquid water at 1 bar is compressed isentropically to 150 bar. First by heating in a boiler, and then by superheating at constant pressure of 150 bar, the water substance is brought to 7500K. After adiabatic reversible expansion in a turbine to 1 bar, it is then cooled in a condenser to saturated liquid. What is the thermal efficiency of the cycle(%)?Answer C A. 23.45% B. 16.23% C. 34.24% D. 18.23%
6. A steam generating plant has two 20 MW turbo-generators. Steam is supplied at 1.7 Mpa and 3200C. Exhaust is 0.006 MPa. Daily average load factor is 80%. The steam generating units operate at 70% efficiency when using bunker fuel having a heating value of 31,150 KJ/kg and an average steam rate of 5 kg steam/KW-hr. Calculate the Mtons of fuel oil/bunker fuel required per 24 hours. Answer A A. 515 B. 432 C. 6.17 D. 762
7. A back pressure steam turbine of 100,000 KW serves as a prime mover in a cogeneration system. The boiler admits the return water at a temperature of 66 0C and produces the steam at 6.5 Mpa and 4550C. Steam then enters a back pressure turbine and expands to the pressure of the process, which is 0.52 Mpa. Assuming a boiler efficiency of 80% and neglecting the effect of pumping and the pressure drops at various location, what is the incremental heat rate of electric? The following enthalpies have been found; turbine entrance = 3306.8 KJ/kg, exit = 2700.8; boiler entrance = 276.23 KJ/kg, exit =3306.8. Answer B A. 21,504 KJ/KW-hr B. 22,504 KJ/KW-hr C. 23,504 KJ/KW-hr D. 24,504 KJ/KW-hr 8. A coal-fired power plant has a turbine-generator rated at 1000 MW gross. The plant required about 9% of this power for its internal operations. It uses 9800 tons of coal per day. The coal has a heating value of 6,388.9 Kcal/kg and the steam generator efficiency is 86%. What is the net station efficiency of the plant in percent? Answer C A. 30% B. 25% C. 33% D. 38% 9. A superheat steam Rankine cycle has a turbine inlet conditions of 17.5 Mpa and 530 0C expands in a turbine to 0.007 Mpa. The turbine and pump polytropic efficiencies are 0.9 and 0.7 respectively, pressure between pump and turbine inlet are 1.5 Mpa. What shoul be the pump work in KJ/kg. Answer B A. 17.3 B. 27.3 C. 37.3 D. 47.3
10. A steam plant operates with initial pressure of 1.70 Mpa and 370 0C temperature and exhaust to a heating syste at 0.17 Mpa. The Condensate from the heating system is returned to the boiler at 65.50C and the heating system utilizes from its intended purpose 90% of the energy transferred from the steam it receives. The n T is 70%. If boiler efficiency is 80%, what is the cogeneration efficiency of the system in percent. Neglect pump work. Answer D Steam Properties: At 1.70 Mpa and 3700C: h = 3187.1 KJ/kg s = 7.1081 At 0.17 Mpa: hf = 483.20 sf=1.4752 hg = 2216.0 sg=5.7062 At 65.50C: hf = 274.14 A. 78
B. 102.10 C. 91.24 D. 69 11. In a cogeneration plant, steam enters the turbine at 4 Mpa and 400 0C. One fourth of the steam is extracted from the turbine at 600 Kpa pressure for process heating. The remaining steam continues to expand to 10 Kpa. The extracted steam is then condensed and mixed with feedwater are constant pressure and the mixture is pumped to the boiler pressure of 4 Mpa. The mass flow rate of steam through the boiler is 30 kg/sec. Disregarding any pressure drops and heat losses in the piping, and assuming the turbine and pump to be isentropic, how much process heat is required in KW? Answer A Steam properties: At 4 Mpa and 4000C: h = 3213.6 KJ/kg, s = 6.7690 At 600 Kpa: hf = 670.56 sf = 1.9312 hfg = 2086.3 sfg = 4.8288 A. 15,646.8 B. 2,458.2 C. 1.9312 D. 1,027.9 12. In an ideal Reheat cycle, the steam throttled condition is 8 Mpa and 480 0C. The steam is then reheated to 2 Mpa and 4600C, determine cycle efficiency. Answer A A. 38.3% B. 24.3% C. 34.3% D. 45.2% 13. A reheat steam cycle has 13,850 Kpa throttle pressure at the turbine inlet and a 2800 Kpa reheat pressure, the throttle and reheat temperature of the steam is 540 0C, condenser pressure is 3.4 Kpa, engine efficiency of high and low pressure is 75% find the cycle thermal efficiency. Answer A A. 34.46% B. 38.40% C. 36.49% D. 43.45%
14. Steam is delivered to turbine at 5.4 Mpa and 6000C. Before condensation at 310C, steam is extracted for feedwater heating at 0.6 Mpa. For an ideal regenerative cycle, find the thermal efficiency. Answer D A. 23.45% B. 34.34% C. 28.34% D. 44.14% 15. A steam condenser receives 10 kg/s of steam with an enthalpy of 2570 KJ/kg. Steam condenses into a liquid and leaves with an enthalpy of 160 KJ/kg. Cooling water passes through the condenser with temperature increases from 13 degrees C to 24 0C/ Calculate the water flow rate in kg/s. Answer C
A. B. C. D.
533 518 523 528
16. In an open feedwater heater for a steam plant, saturated steam at 7 bar is mixed with subcooled liquid at 7 bar and 250C. Just enough steam is supplied to ensure that the mixed steam leaving the heater will be saturated liquid at 7 bar when heater efficiency is 90%. Calculate the mass flow rate of subcooled liquid if steam flow rate is 0.865 kg/s. Steam Properties are: Answer A At 7 bar, saturated vapor: hg = 2763.5 KJ/kg At 7 bar, and 250C: hf = 105.5 KJ/kg At 7 bar, saturated liquid: hf = 697.22 KJ/kg A. 2.725 B. 3.356 C. 2.286 D. 3.948 ` 17. Steam expands adiabatically in a turbine from 2000 Kpa, 400 0C to 400 Kpa, 2500C. What is the effectiveness of the process in percent assuming an atmospheric pressure of 15 0C. Neglect changes in kinetic and potential energy. Answer C Steam Properties are: At 2000 Kpa and 4000C. h = 3247.6 KJ/kg s = 7.1270 KJ/kg-K At 400 Kpa and 2500C. h = 2964.2 KJ/kg s=7.3789 KJ/kg-K A. 82 B. 84 C. 80 D. 86
19. Steam enters the turbine of a cogeneration plant at 0.7 Mpa and 500 0C. Steam at a flow rate of 7.6 kg/s is extracted from the turbine at 600 Kpa pressure for process heating. The remaining steam continues to expand to 10 Kpa. The recovered condensates are pumped back to the boiler. The mass flow rate of steam that enters the turbine is 30 kg/s. Calculate the cogeneration efficiency in percent. Answer No exact answer in the choices Steam Properties At 7.0 Mpa and 5000C: h = 3410.3 s = 6.7976 At 600 Kpa: hf = 670.56 hfg = 2086.3 sfg = 4.8288
At 10 Kpa: hf = 191.83 hfg = 2392.8 sf = 0.6493 sfg = 7.5009 A. 60 B. 50 C. 65 D. 55 20. A heat exchanger was installed purposely to cool 0.50 kg of gas per second. Molecular weight is 28 and k = 1.32. The gas is cooled from 150 0C to 800C. Water is available at the rate of 0.30 kg/s and at a temperature of 120C. Calculate the exit temperature of the water in 0C. Answer A A. 48 B. 42 C. 46 D. 44 21. Pump work of Rankine cycle is 15 KJ/kg. Density of water entering the pump is 958 kg/m 3. If condenser pressure is 100 Kpa, what is the pressure at the entrance of the turbine? Answer A A. 14.47 Mpa B. 20.48 Mpa C. 15.67 Mpa D. 17.77 Mpa 22. In a Rankine cycle the turbine work is 1,000 KJ/kg and pump work of 13 KJ/kg. If heat generated by generator is 2800 KJ/kg, what is the efficiency of the cycle? Answer A A. 35.25% B. 4.75% C. 38.65% D. 30.25%
23. In a Reheat power plant the difference in enthalpy at the entrance and exit is 550 KJ/kg for first stage and second stage is 750 KJ/kg. If both stages has an efficiency of 92% and heat added to boiler is 3,000 KJ/kg. Determine the plant cycle efficiency neglecting the pump work. Answer C A. 30% B. 35% C. 40% D. 45% 24. An adiabatic feed pump in a steam cycle delivers water to a steam generator at a temperature of 2000C and a pressure of 10 Mpa. The water eneters the pump as a saturated liquid at 180 0C. If the power supplied to the pump is 75 kW, determine the mass flow rate. Answer C A. 6.23 kg/s B. 8.34 kg/s C. 7.39 kg/s D. 9.12 kg/s
25. A condenser receives steam from a turbine at 15 kPa, 90% quality, and with a velocity of 240 m/s. Determine the increase in circulating water required because of high pressure exit velocity if the steam flow rate is 38 kg/s and the cooling water temperature rise is12 0C with an inlet condition of 300C. Answer D A. 11.23 kg/s B. 17.23 kg/s C. 13.23 kg/s D. 21.78 kg/s 26. A steam generator has an exit enthalpy of 3195.7 KJ/kg at the rate of 10 kg/s. The enthalpy available at the turbine inlet is 3000 KJ/kg. Determine the heat lost between boiler outlet and turbine inlet. Answer B A. 1957 kW B. -1957 kW C. 1873 kW D. -1873 kW 27. A Rankine cycle has a turbine with available enthalpy of 800 KJ/kg. The pump has also 10 KJ/kg energy available. Find the net cycle output of the plant if mass flow rate is 5 kg/s. Answer B A. 2619 kW B. 3950 kW C. 8745 kW D. 4234 kW 28. A Rankine cycle, the steam is extracted from the turbine at 2 Mpa and 250 0C for feedwater heating and it is mixed with condenser exit at 30 Kpa after pumping. Find the fraction of vapor extracted from the turbine. Answer A A. 0.23464 B. 0.19338 C. 0.5632 D. 0.3855 29. An adiabatic turbine in a steam generating plant receives steam at a pressure of 7.0 Mpa and 5500C and exhausts at 20 kPa. The turbine inlet is 3 m higher than the turbine exit, the inlet steam velocity is 15 m/s and the exit is 300 m/s. Calculate the turbine work in KJ/kg. Answer B A. 1297.45 B. 1197.10 C. 1093.45 D. 1823.45 30. A steam power plant operates on the Rankine cycle. The steam enters the turbine at 7 Mpa and 5500C with a velocity of 30 m/s. It discharge to the condenser at 20 kpa with a velocity of 90 m/s. Calculate the net work in kW for a flow of 37.8 kg/s. Answer D A. 23.23 MW B. 53.34 MW C. 34.22 MW D. 46.54 MW
31. A Carnot cycle uses steam as the working substance and operates between pressure of 7 Mpa and 7 kpa. Determine the cycle thermal efficiency. Answer A A. 44.17% B. 54.23% C. 34.23% D. 59.4% 32. A supercritical power plant generates steam at 25 Mpa and 560 0C. The condenser pressure is 7.0 kpa. Determine the exit quality of steam if it expands through a turbine in this power plant. Answer D A. 45.66% B. 68.45% C. 56.56% D. 74.26% 33. Steam enters a turbine at 1.4 Mpa and 320 0C. The turbine internal efficiency is 70%, and the total requirement is 800 kW. The exhaust is to the back pressure system, maintained at 175 kpa. Find the steam flow rate. Answer A A. 2.62 kg/s B. 4.23 kg/s C. 3.23 kg/s D. 5.34 kg/s
BOILERS 1. The heating surface are of water tube boiler is 200 m 2, what is the equivalent rated boiler horsepower? Answer D A. 217 Hp B. 2365.93 Hp C. 200 Hp D. 219.78 Hp 2. The rated boiler horsepower of a fire tube boiler is 500 Hp. What is the heating surface area of the boiler? Answer D A. 500 m2 B. 300 m2 C. 400 m2 D. 550 m2 3. A water tube boiler has a heating surface area of 500 m 2. For a developed boiler hp of 825. Determine the percent rating of the boiler. Answer C A. 120.15% B. 160.15% C. 150.15% D. 300.15%
4. The factor of evaporation of boiler is 1.1 and a steam rate of 0.79 kg/sec. What is the developed boiler horsepower? Answer B A. 300 B. 200 C. 869 D. 250 5. The percent rating of water tube boiler is 200%, factor of evaporation of 1.08 and heating surface area is 256 m2. Find the rate of evaporation. Answer A A. 8,153.02 kg/hr B. 5,153.02 kg/hr C. 7,200 kg/hr D. 8,500.46 kg/hr 6. The actual specific evaporation of a certain boiler is 10. Factor of evaporation is 1.05. If the heating value of fuel is 30,000 KJ/kg, find the boiler efficiency. Answer A A. 60% B. 65% C. 70% D. 79% 7. The ASME evaporation units of a boiler is 24,827,000 KJ/hr. The boiler auxiliaries consume 1.5 MW. What is the net boiler efficiency if the heat generated by the fuel is 30,000 KJ/kg?Answer A A. 64.75% B. 68.94% C. 62.76% D. 68.54% 8. A 100,000 kg of coal supplied two boilers. One has a capacity of 150 kg/hr. How many days to consume the available fuel if the other boiler consumes 200 kg/hr? Answer D A. 5 days B. 7 days C. 15 days D. 12 days 9. The following coal has the following ultimate analysis by weight: C = 70.5% H2 = 4.5% O2 = 6.0% N2 = 1.0% S = 3.0% Ash = 11% Moisture = 4% A stocker fired boiler of 175,000 kg/hr steaming capacity uses this coal as fuel. Calculate volume of air in m3/hr with air at 600F and 14.7 psia pressure if boiler efficiency is 70% and FE = 1.10. Answer A A. 212,830 m3/hr B. 215,830 m3/hr C. 213,830 m3/hr D. 214,830 m3/hr 10. The following coal has the following ultimate analysis by weight: C = 70.5% H2 = 4.5% O2 = 6.0% S = 3.0% Ash = 11% Moisture = 4%
N2 = 1.0%
A stocker fired boiler of 175,000 kg/hr steaming capacity uses this coal as fuel. Volume of air in m3/hr with air at 600F and 14.7 psia pressure. Weight in metric tons of cal needed for 24 hours operation at rated capacity if boiler efficiency is 70% and FE = 1.10. Answer D A. 503.443 Mtons B. 508.443 Mtons C. 502.443 Mtons D. 504.443 Mtons 11. Two boilers are operating steadily on 91,000 kg of coal contained in a bunker. One boiler is producing 1591 kg of steam per hour at 1.2 factor of evaporation and an efficiency of 65% and another boiler produced 1364 kg of steam per hour at 1.15 factor of evaporation and an efficiency of 60%. How many hours will the coal in the bunker run the boilers if the heating value of coal is 7590 Kcal/kg.Answer C A. 220.8 hrs B. 256.2 hrs C. 230.8 hrs. D. 453.3 hrs. 12. A steam generating plant consisting of a boiler, an economizer and superheater generates superheated steam at the rate of 50 tons/hr. Feed water enters the boiler at 5 Mpa and 120 0C. Steam leaves the superheater at 4.5 Mpa and 320 0C. If the coal used has a heating value of 30,000 KJ/kg, calculate the number of tons of coal fired per hour for a gross efficiency of 85%. Answer A A. 4.89 B. 6.34 C. 5.34 D. 45.5 13. A water tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3, boiler rating is 200%, boiler efficiency is 5%, heating surface area is 0.91 m 2/boiler Hp, and the heating value of fuel is 18,400 Kcal/kg. The total coal available in the bunker is 50,000 kg. Determine total number of hours to consume the available fuel. Answer D A. 533.45 B. 743.12 C. 634.34 D. 853.26 14. A boiler operating at 11 kg/cm2 is required to generate a minimum of 50,000 kj/hr of saturated steam. Feed water enters the boiler at 80 0C. Compute the fore coal at an average rate 4,800 kg/hr and boiler efficiency is 85%. Compute the minimum heating value of local coal that could be used in order to ensure the generation of required steam. Answer B A. 28,464 B. 29,977 C. 23,556 D. 30,976 15. A boiler operating at 11 kg/cm2 is required to generate a minimum of 50,000 kg/hr of saturated steam. Feed water enters the boiler at 80 0C. The furnace is designed to fire coal at an average rate 4,800 kg/hr and boiler efficiency is 85%. Compute the developed boiler horsepower. Answer A A. 3462.56 hp
B. 1234.56 hp C. 2345.67 hp D. 4233.34 hp 16. A steam boiler generating 7.1 kg/s of 4.137 Mpa, 426.7 0-C steam is continuously blown at the rate of 0.31 kg/sec. Feed water enters the economizer at 149.9 0C. The furnace burns 0.75 kg coal/sec of 30,470.6 KJ/kg higher heating value. Calculate the overall thermal efficiency of steam boiler. Answer C A. 76.34% B. 84.23% C. 82.78% D. 88.34% STEAM ENGINE 1. A steam engine has 10% brake thermal efficiency and delivers 750 kg/hr steam. The enthalpy of engine entrance is 2800 KJ/kg and condenser exit is 450 KJ/kg. Determine the brake power of the engine. Answer C A. 46 KW B. 47 KW C. 49 KW D. 48 KW
2. The indicated efficiency of a steam engine is 60%. The engine entrance is 2700 KJ/kg and exit is 2000 KJ/kg. If steam consumption is 800 kg/hr and mechanical efficiency is 90%, what is the brake power of the engine? Answer B A. 55 KW B. 84 KW C. 65 KW D. 70 KW 3. A steam engine has bore and stoke of 300 mm x 420 mm running at 250 rpm has mean indicated pressure of the engine is 400 Kpa. Determine the indicate power. Answer D A. 100 KW B. 50 KW C. 65 KW D. 99 KW 4. The crank shaft of a double acting steam engine rotates at 220 rpm. The bore and stroke of the steam engine is 300 mm x 450 mm, and the mean effective pressure acting upon the piston is 4 kg/cm2. Find the indicated horsepower developed in the cylinder. Answer A A. 122.7 hp B. 110.3 hp C. 143.2 hp D. 176.3 hp
5. A steam engine develops 60 Bhp with dry saturated steam at 1034.25 Kpa absolute and exhaust at 124.11 Kpa. Steam consumption is 736.36 kg/hr. Calculate the indicated engine efficiency based on 90% mechanical efficiency. Answer D A. 34.23% B. 54.23% C. 45.23% D. 66.74% 6. A steam engine develops 60 Bhp with dry saturated steam at 1034.25 Kpa absolute and exhaust at 124.1 Kpa. Steam consumption is 736.36 kg/hr. calculate the thermal efficiency of equivalent Rankine engine. Answer A A. 15.59% B. 34.23% C. 12.45% D. 21.34% 7. A 350 mm x 450 mm engine running at 260 rpm has an entrance steam condition of 2 Mpa and 2300C and exit at 0.1 Mpa. The steam consumption is 2,000 kg/hr and mechanical efficiency is 88%. If indicated mean effective pressure is 600 Kpa, determine the brake thermal efficiency. Answer C A. 23.34% B. 18.34% C. 14.66% D. 27.34% 8. A 350 x 450 mm engine running at 260 rpm has an entrance steam condition of 2 Mpa and 230 0C and exit at 0.1 Mpa. The steam consumption is 2,000 kg/hr and mechanical efficiency is 88%. If indicated mean effective pressure is 600 Kpa, determine indicated thermal efficiency. Answer A A. 16.66% B. 34.23% C. 12.34% D. 21.23% 9. Steam is admitted to the cylinder of an engine in such a manner that the average pressure is 120 psi. The diameter of the piston is 10” and the length of stroke is 12”. Answer D A. 171.5 B. 175 C. 173.2 D. 174.4 STEAM TURBINE 1. A steam turbine receives 5,000 kg/hr of steam at 5 Mpa and 400 0C and velocity of 25 m/sec. It leaves the turbine at 0.006 Mpa and 85% quality and velocity of 20 m/sec. Radiation is 10,000 KJ/hr. Find the KW developed. Answer C A. 1273.29 B. 2173.29 C. 1373.29 D. 7231.29
2. An industrial power plant requires 1.5 kg of dry saturated steam per second at 165 0C for heating purposes. This steam may be supplied from an extraction turbine which receives steam at 4 Mpa and 3800C and is exhaust to condenser at the rate of 0.8 kg steam per second at 0.0034 Mpa while rejecting 1400 KW to the cooling water. If mechanical-electrical efficiency is 95% and that the heat loss in the turbine casing is 10 KW, calculate the power generated by the plant. Answer B A. 2,126.44 KW B. 1,556.50 KW C. 3,123.34 KW D. 4,344.33 KW 3. A steam turbine with 90% stage efficiency receives steam at 7 Mpa and 550 0C and exhausts as 20 Kpa. Determine the turbine work. Answer A A. 117 KJ/kg B. 132 KJ/kg C. 123 KJ/kg D. 143 KJ/kg 4. A steam turbine with 90% stage efficiency receives steam at 7 Mpa and 550 0C and exhausts as 20 Kpa. Determine the quality at exhaust. Answer D A. 87.45% B. 76.34% C. 82.34% D. 91.69% 5. A small steam turbine power plant of 5,000 KW capacity has a full load steam rate of 6 kg steam pwer KW-hr. No load steam consumption may be taken as 10% of the full load steam consumption. Write the equations of WILLANS LINE of this turbine and at 60% of rated load, calculate the hourly steam consumption of this unit. Answer C A. 19,100 kg/hr B. 19,300 kg/hr C. 19,200 kg/hr D. 19,400 kg/hr 6. Steam flows into a turbine at the rate of 10 kg/sec and 10 KW of heat are lost from the turbine. Ignoring elevation and kinetic energy effects, calculate the power output from the turbine. Inlet enthalpy is 2739 KJ/kg and exhaust enthalpy is 2300.5 KJ/kg. Answer C A. 4605 KW B. 4973 KW C. 4375 KW D. 4000 KW 7. Steam entering the turbine has a rate of 10 kg/sec with enthalpy of 3400 KJ/kg and 2600 KJ.kg at the exhaust. If 100 KW of heat is rejected from turbine casing, what is the turbine work? Answer A A. 7900 kW B. 7700 KW C. 5600 KW D. 5400 KW
8. A steam turbine of 6 MW capacity has a Willian’s line equation of m s = 5.5L + 3,000 kg/hr. Determine the steam consumption at 70% load. Answer C A. 3564 kg/hr B. 3546 kg/hr C. 26,100 kg/hr D. 58,000 kg/hr 9. A steam turbine has an entrance enthalpy of 3050 KJ/kg. The exit has 2500 KJ/kg. Determine the actual enthalpy after isentropic expansion if stage efficiency is 90%. Answer B A. 1255 KJ/kg B. 2555 KJ/kg C. 2500 KJ/kg D. 2000 KJ/kg 10. Steam enters the turbine at the rate of 2.5 kg/sec with enthalpy of 3200 KJ/kg and exhaust enthalpy of 1100 KJ/kg. Steam is extracted from the turbine at the rate of 1 kg/sec for heating purposes with enthalpy of 2750 KJ/kg. What is the turbine work? Answer D A. 2000 KW B. 2500 KW C. 3000 KW D. 3600 KW 11. A steam turbine has an entrance enthalpy of 3400 KJ/kg and 2500 KJ/kg at exit. If generator generates 2430 KW and has 90% efficiency, what is the mass of steam entering the turbine? Answer D A. 10,400 kg/hr B. 10,600 kg/hr C. 10,700 kg/hr D. 10,800 kg/hr
12. Steam turbine in Rankine cycle has an exhaust enthalpy of 2650 KJ/kg and delivers 0.8 kg/sec of steam. Determine the heat rejected from the condenser if enthalpy at exit is 200 KJ/kg. Answer A A. 1960 KW B. 1940 KW C. 1995 KW D. 1909 KW GEOTHERMAL POWER PLANT 1. Mass low rate of ground water in a geothermal power plant is 1,500,000 kg/hr and the quality after throttling is 30%. Determine the brake power of turbine if the change of enthalpy of steam at inlet and outlet is 700 KJ/kg. Answer B A. 68.5 MW B. 87.5 MW C. 64.5 MW D. 89.5 MW
2. Ground water of geothermal power plant has an enthalpy of 700 KJ/kg and at turbine inlet is 2,750 KJ/kg and enthalpy of hot water in flash tank is 500 KJ/kg. What is the mass of steam flow entering the turbine if mass flow of ground water is 45 kg/sec? Answer C A. 3.27 kg/sec B. 2.27 kg/sec C. 4.27 kg/sec D. 9.27 kg/sec 3. The enthalpy entering the turbine of a geothermal power plant is 2750 KJ.kg and mass rate of 1 kg/sec. The turbine brake power is 1000 KW condenser outlet has enthalpy of 210 KJ/kg. If temperature rise of cooling water in condenser is 8 0C, what is the mass of cooling water requirement? Answer C A. 44 kg/sec B. 45 kg/sec C. 46 kg/sec D. 47 kg/sec 4. In a 12 MW geothermal power plant, the mass flow of steam entering the turbine is 26 kg/sec. The quality after throttling is 25% and enthalpy of ground water is 650 KJ/kg. Determine the overall efficiency of the plant. Answer D A. 7.4% B. 9.6% C. 5.4% D. 15.4% 5. A 16,000 KW geothermal plant has a generator efficiency and turbine efficiency of 90% and 80%, respectively. If the quality after throttling is 20% and each well discharges 200,000 kg/hr, determine the number of wells are required to produce if the change in enthalpy at the entrance and exit of turbine is 500 KJ/kg. Answer A A. 4 wells B. 5 wells C. 6 wells D. 8 wells 6. A geothermal power plant draws pressurized water from a well at 20 Mpa and 300 0C. To produce a steam water mixture in the separator, where the unflashed water is removed, this water is throttled to a pressure of 1.5 Mpa. The flashed steam which is dry and saturated passes through the steam collector and enters the turbine at 1.5 Mpa and expands to 1 atm. The turbine efficiency is 85% at a rated power output of 10 MW. Calculate overall plant efficiency. Answer A A. 7.29% B. 12.34% C. 9.34% D. 19.45% 7. A flashed steam geothermal power plant is located where underground hot water is available as saturated liquid at 700 Kpa. The well head pressure is 600 Kpa. The flashed steam enters a turbine at 500 Kpa and expands to 15 Kpa, when it is condensed. The flow rate from the well is 29.6 kg/sec. Determine the power produced in KW. Answer A A. 430.13 kg/s B. 540.23 kg/s
C. 370.93 kg/s D. 210.34 kg/s 8. A flashed steam geothermal power plant is located where underground hot water is available as saturated liquid at 700 Kpa. The well head pressure is 600 Kpa. The flashed steam enters a turbine at 500 Kpa and expands to 15 Kpa, when it is condensed. The flow rate from the well is 29.6 kg/sec. Determine the cooling water flow in kg/sec if water is available at 30 0 C and a 100C rise is allowed through the condenser. Answer DIESEL POWER PLANT 1. Determine the indicated mean effective pressure of an engine in psi having a brake mean effective pressure of 750 Kpa and 80% mechanical efficiency. Answer A A. 136 psi B. 137 psi C. 138 psi D. 140 psi 2. Determine the friction power of an engine if the frictional torque developed is 0.3 KN.m running at 1200 rpm. Answer B A. 40.6 KW B. 37.7 KW C. 36.5 KW D. 50.3 KW 3. What is the power developed in the cylinder if indicated thermal efficiency is 44%, the engine uses 0.05 kg/sec fuel with heating value of 44,000 KJ/kg? Answer C A. 1000 KW B. 775 KW C. 968 KW D. 588 KW 4. A 750 KW diesel electric plant has a brake thermal efficiency of 34%. If the heat generated by fuel is 9,000,000 KJ/hr, what is the generator efficiency? Answer D A. 85.33% B. 65.88% C. 75.55% D. 88.23% 5. A 16-cylinder V-type diesel engine is directly coupled to a 5000 KW AC generator. If generator efficiency is 90%, calculate the brake horsepower of the engine. Answer A A. 7447 Hp B. 6468 Hp C. 8542 Hp D. 7665 Hp 6. Determine the brake power of the engine having a brake thermal efficiency of 35% and uses 250API fuel consumption of 40 kg/hr. Answer B or C A. 165.84 KW B. 173.52 KW
C. 173.52 KW D. 160.67 KW 7. Determine the specific gravity of fuel oil having a heating value of 44,899.2 KJ/kg. Answer D A. 0.90 B. 0.80 C. 0.877 D. 0.893 8. A 500 KW diesel engine operates at 101.3 Kpa and 27 0C in Manila. If the engine will operate in Baguio having 93 Kpa and 230C, what new brake power will developed if mechanical efficiency is 85%? Answer C A. 600 KW B. 754 KW C. 459 KW D. 971 KW 9. What is the displacement volume of 300 mm x 4400 mm, 4 – stroke, 1200 rpm, 8 cylinder diesel engine? Answer B A. 0.243 m3/sec B. 2.262 m3/sec C. 5.75 kg/sec D. 1.25 m3/sec 10. What is the friction horsepower of a 300 KW diesel engine having a mechanical efficiency of 86%? Answer D A. 86.5 Hp B. 87.5 Hp C. 90.5 Hp D. 65.5 Hp 11. Determine the output power of a diesel power plant if the engine and generator efficiency is 83% and 95%, respectively. The engine uses 25 0API fuel and has a fuel consumption of 0.08 kg/sec. Answer D A. 2795 KW B. 8642 KW C. 9753 KW D. 2815 KW 12. Determine the piston speed of a 250 mm x 300 mm diesel engine running at 1200 rpm. Answer B A. 6 m/sec B. 12 m/sec C. 18 m/sec D. 5 m/sec 13. Determine the speed of a 6-pole generator of 60 hz. Answer C A. 600 rpm B. 1000 rpm C. 1200 rpm D. 3600 rpm
14. A 50 Bhp blast furnace engine uses fuel with 10 ft 3/Bhp-hrs. The heating value of gas is 33,500 KJ/m3. Determine the brake thermal efficiency. Answer D A. 80% B. 50% C. 25.76% D. 28.31% 15. The heat generated by fuel is 2500 KW. If the jacket water loss is 30%. Determine the mass of water circulated in the engine if the temperature rise is 8 0C. Answer B A. 20.5 kg/sec B. 22.4 kg/sec C. 58.5 kg/sec D. 12.3 kg/sec 16. An engine-generator rated 9000 KVA at 80% power factor, 3 phase, 4160 V has an efficiency of 90%. If overall plant efficiency is 25%, what is the heat generated by the fuel. Answer B A. 18,800 KW B. 28,800 KW C. 7500 KW D. 20,000 KW 17. A 4-strok, 8 cylinder diesel engine with bore and stroke of 9 in. x 12 in, respectively and speed of 1000 rpm has a break mean effective pressure of 165 psi. Determine the engine brake horsepower. Answer D A. 1753.34 Hp B. 1850.34 Hp C. 1950.34 Hp D. 1272.34 Hp 18. What torque is developed by the 300 KW engine running at 900 rpm? Answer C A. 2.65 KN.m B. 6.85 KN.m C. 3.18 KN.m D. 5.65 KN.m 19. What is the mechanical efficiency of a diesel engine if friction power is 30 KW and brake power of 150 KW? Answer B A. 85.55% B. 83.33% C. 65.44% D. 75.88% 20. A 3 MW diesel engine consumes 240 liters of 25 0API fuel generates 900 KW-hr. Determine the rate of fuel consumed by the engine. Answer A A. 0.2 kg/sec B. 0.4 kg/sec C. 0.6 kg/sec D. 0.8 kg/sec
21. The indicated thermal efficiency of a two stroke diesel engine is 50%. If friction power is 3% of heat generated, determine the brake thermal efficiency of the engine. Answer D A. 33% B. 34% C. 36% D. 37% 22. During the dynamometer test of an engine for 1 hr steady load, the engine consumes 40 kg fuel having 43,000 KJ/kg heating value. If the torque developed is 2.5 KN-m during the test at 600 rpm, what is the brake thermal efficiency of the engine? Answer B A. 31.22% B. 32.88% C. 55.77% D. 25.99% 23. A waste heat recovery boiler generates 250 kg/hr with h s – hf = 2300 KJ/kg. What is the exhaust loss from the engine if the actual heat developed is 35%? Answer C A. 492.6 KW B. 365.7 KW C. 456.4 KW D. 845.4 KW 24. What maximum power that can be delivered by the 2000 KW engine at 3000 ft elevation considering the pressure effect alone? Answer D A. 1600 KW B. 1700 KW C. 1900 KW D. 1800 KW 25. A 1000 KW diesel engine operates at an altitude of 1500 m elevation. Considering the pressure effect alone, find the power developed by the engine at higher elevation? Answer D A. 753 KW B. 823 KW C. 345 KW D. 983 KW 26. The piston speed of an inches. Answer C A. B. C. D.
engine running at 1200 rpm is 12 m/s. Find the stroke of the engine in 15.74 mm 16 in 300 mm 15.75 in
27. The density of air entering the engine is 1.176 kg/m 3 has a volume flow rate of 0.375 m 3/sec. If the air fuel ratio is 21, find the mass flow rate of fuel. Answer B A. 0.10 kg/sec B. 0.02 kg/sec C. 0.30 kg/sec D. 0.40 kg/sec
28. A diesel engine develops a torque of 5 KN-m at 1800 rpm. If the brake thermal efficiency is 31%, find the heat generated by the fuel. Answer B A. 3050.25 KW B. 3040.25 KW C. 3000.25 KW D. 5000 KW 29. In a diesel engine the fuel is injected at 6.5% of the stroke, the clearance volume is 10% of the stroke. Find the cut-off ratio. Answer B A. 1.80 B. 1.65 C. 1.70 D. 1.40 30. A 373 KW (500 Hp) internal combustion engine has a break mean effective pressure of 551.5 Kpa at full load. What is the friction power if mechanical efficiency is 85%? Answer A A. 88.23 hp B. 97.33 hp C. 56.34 hp D. 76.23 hp 31. A 4-stroke 394 mm bore and 534 mm stroke single acting diesel engine with four cylinders is guaranteed to deliver 350 Bhp at 300 rpm. The engine consumed 66.8 kg/hr of fuel with a heating value of 44,251 KJ/kg. Calculate indicated mean effective pressure in Kpa if mechanical efficiency is 89%. Answer A A. 450.8 kpa B. 234.5 kpa C. 345.6 kpa D. 643.2 kpa 32. A 305 mm x 457 mm four stroke single acting diesel engine is rated at 150 KW at 260 rpm. Fuel consumption at rated load is 0.26 kg/KW-hr with a heating value of 43,912 KJ.kg. Calculate brake thermal efficiency. Answer A A. 31.53% B. 27.45% C. 45.34% D. 54.23% 33. A four-stroke, 8 cylinder Diesel engine with bore and stroke of 9 inches and 12 inches, respectively and speed of 950 rpm has a brake effective pressure of 164 psi. The specific fuel consumption is 0.39 lb/bhp-hr and fuel heating value is 18,500 Btu/lb. Determine thermal efficiency. Answer A A. 35.27% B. 45.23% C. 38.23% D. 54.23% 34. A dynamometer test was done for one hour at steady load on a 6 cylinder diesel engine. It was found to use 42 kg of fuel having Qh = 42,000 J/g. Cylinder is 22.8 cm x 27.2 cm, 4-cycle type.
Speed, 550 rpm and efficiency. Answer A A. B. C. D.
dynamometer torque at 27000 kg-cm. Determine the brake thermal 31.13% 43.22% 35.34% 45.32%
35. A certain diesel engine with the following classification, 8 cylinder, 400 mm x 600 mm, four stroke cycle has a fuel consumption of 0.6 lbs/hp-hr based on 19,100 Btu/lb. Engine speed is 280 rpm with an indicated mean effective pressure 130 psi. If the jacket water carries away an estimated 25% of the heat supplied, find its capacity (gpm) required if the allowable rise is 40 0F. Answer C A. 234 B. 873 C. 242 D. 292 36. When the pressure is 101.325 Kpa and temperature is 27 0C, a diesel engine has the full-throttle characteristics listed: Brake power = 275 KW Brake specific fuel consumption = 0.25 kg/KW-hr Air fuel ratio = 22 Mechanical efficiency = 88% If the engine is operated at 84.5 Kpa and temperature of 15.5 0C, find the brake specific fuel consumption kg/kwh. A. 0.294 B. 0.862 C. 0.423 D. 1.08 37. Find the power which a 2.5 MW natural gas engine can develop at an altitude of 1981.2 meters taking into consideration the pressure and temperature change. Answer: B A. 2.34 MW B. 1.912 MW C. 2.56 MW D. 1.67 MW 38. A 119 KW, six cylinder, 589 mm x 711 mm, 225 rp, four stroke diesel engine has a fuel consumption of 0.23 kg/KWh based on 44,099 KJ/kg fuel (heating value). A waste heat recovery boiler recovers 35% of the exhaust loss. Jacket water loss are estimated at 30%. Assume losses due to friction, etc. at 8%. Calculate the quantity of 136 Kpa steam that can be produced in kg/hr, if jacket water at 70oC is used for boiler feed. Answer: A A. 439.4 kg/hr B. 623.4 kg/hr C. 543.32 kg/hr D. 984.45 jg/hr 39. A 2000 KW diesel engine unit uses 1bbl oil per 525 KWH produced. Oil is 25 oAPI. Efficiency of generator 93%, mechanical efficiency of engine 80%. What is the thermal of engine on indicated power(%)?Answer:C A. 31.69
B. 29.47 C. 39.60 D. 35.60 40. A waste heat recovery boiler produces 4.8 Mpa (dry saturated) steam from 104 °C feedwater. The boiler receives energy from 5 kg/sec of 954°C dry air. After passing through a waste heat boiler, the temperature if the air has been reduce to 343°C. How much steam in kg produced per second? Note: Ar 4.80 Mpa dry saturated, h = 2796. A. 1.3 B. 0.92 C. 2.1 D. 3.4 41. A diesel electric plant supplies energy for Meralco. During a 24 hour period, the plant consumed 200 gallons of fuel at 28°C and produced 3930 KW-hr. Industrial fuel used is 28°API and was purchased at P5.50 per liter at 15.6°C. What is the cost of fuel be to produce one KW-hr? Answer: A A. P1.05 B. P1.10 C. P1.069 D. P.00
42. A single-acting, four cylinder, 4 stroke cycle diesel engine with a bore x stroke of 21.59 x 27.94 cm, operating at 275 rpm, consumes 8.189 kg/hr of fuel whose heating value is 43,961.4 KJ/kg. The indicated mean effective pressure is 475.7 kpa. The load on the brake arm, which is 93.98 cm is 113.4 kg. What is the brake mean effective pressure in Kpa? Answer: A A. 415.20 B. 124.17 C. 319.95 D. 645.33 43. A supercharged six-cylinder four stroke cycle diesel engine of 10.48 cm bore and 12.7 cm stroke has a compression ratio of 15. When it is tested on a dynamometer with a 53.34 cm arm at 2500 rpm, the scale reads 81.65 kg 2.86 kg of fuel of 45,822.20 KJ/kg heating value are burned during a 6 min test, and air metered to the cylinder at the rate of 0.182 kg/sec. Find the brake thermal efficiency.Answer: 0.327 A. 0.327 B. 0.67 C. 0.307 D. 0.357
44. In a double acting, 2 stroke compression ignition engine, 8-cylinder, the diameter of the cylinder is 700 mm, stroke is 1350 mm and the piston rod diameter is 250 mm. When running at 108 rpm, the indicated mean effective pressure above and below the piston are 5.80 abr and 4.90 bar respectively. Calculate the brake power of the engine with a mechanical efficiency of 80% in kilowatts.Answer: B A. 6050 B. 6030 C. 6010 D. 6070 45. In a test laboratory, it was found out that of the 80 Bhp developed by an engine on the test, 45 Ho are absorbed by the cooling water that is pumped through the water jacket and the radiator. The water enters the top of the radiator at 200°F. At that temperature, enthalpy of the water is 168.7 Btu/lb. Water leaves the bottom of the radiator at 190°F and with an enthalpy of 158.03 Btu/lb. What is the water flow rate fir a steady-state oeration? Answer: C A. 25 gpm B. 20 gpm C. 23 gpm D. 24 gpm 46. A sic cylinder, four stroke diesel engine with 76 mm bore x 89 mm stroke was run in the laboratory at 2000 rpm, when it was found that the engine torque was out. The engine consumed 12.2 kg of fuel per hour with heating value of 54,120 KJ/kg and 252.2 kg of air at 15.6°C per hour. Determine the indicated power.Answer: B A. 32.1 kw B. 38.4 kw C. 23.3 kw D. 48.3 kw
47. A waste heat recovery boiler receives energy from 10 kg/s of 950°C hot gases from a diesel engine. The exit temperature of hot gases (C p = 1.0) has been reduced tp 250°C. Steam is produced at 5 Mpa (dry saturated) from 95°C feedwater. How much steam in kg is produced per hour? At 5 Mpa, hg = 2794.3 KJ/kgAnswer: A A. 10,515 B. 10,155 C. 11,055 D. 11,515 48. A six cylinder, four stroke cycle diesel engine has an engine thermal efficiency of 34%. The engine was tested on a dynamometer with a 23 in arm, running at 1800 rpm, the scale reads 210 lbs. During the 15 min test, the engine uses fuel with 28°API and air metered to the cylinder at the rate of 0.201 kg/s. Find the fuel consumption during the 15 min test.Answer: C A. 6.33 liters B. 5.97 liters C. 6.83 liters D. 8.97 liters
49. A3 MW diesel electric power plant uses 3700 gallons in a 24 hour period. Oil is 25°API. What is the thermal efficiency if the engine based on indicated power if the generator is 90% efficiency and 95% mechanical efficiency is assumed?Answer: B A. 55% B. 60% C. 65% D. 70% 50. A single acting, 8 cylinder, 4 stroke cycle diesel engine with a bore to stroke of 15.24 cm x 22.86 cm, operates at 1200 rpm. The load on the brake arm which is 101.60cm is 120 kg. What is the brake mean effective pressure in Kpa?Answer: A A. 450.5 kpa B. 455.5 kpa C. 445.5 kpa D. 495.5 kpa 51. A six cylinder four stroke diesel with 76 mm bore and 89 mm stroke was run in the laboratory at 2000 rpm. The engine consumed 137.4 kg of air at 15.5°C per hour. Determine the volumetric efficiency of air only.Answer: D A. 69.84% B. 88.32% C. 92.54% D. 77.23% GAS TURBINE POWER PLANT 1. An air-standard Braytin cycle has a pressure ratio of 12. Find the thermal efficiency of the cycleAnswer: B A. 34.23% B. 50.83% C. 56.32% D. 65.23% 2. An air standard Braytin cycle has an air leaving the high-temperature heat exvhanger at 850°C and leaving the turbine at 310°C. What is the thermal efficiency?Answer: C A. 42.21% B. 23.34% C. 48.08% D. 56.34% 3. An air standard Brayton cycle has a pressure ratio of 8. The air properties at the start of compression are 100 kpa and 25°C. The maximum allowable temperature is 1100°C. Determine the net work.Answer: A A. 373.24 KJ/kg B. 283.45 KJ/kg C. 321.34 KJ/kg D. 398.23 KJ/kg 4. The air standard Brayton cycle has a net power output of 100 kw. The working substance is air, entering the compressor at 30°C, leaving the high-temperature heat exchanger at 750°C and leaving the turbine 300°C. Determine the mass flow rate of air.Answer: A
A. B. C. D.
1698 kg/hr 1756 kg/hr 1543 kg/hr 2344 kg/hr
5. The compressor for an actual gas turbine requires 300 KJ/kg of work to quadruple the inlet pressure. The inlet air temperature is 100°C. Determine the compressor air exit temperature.Answer: D A. 234°K B. 542°K C. 653°K D. 673°K 6. The compressor for an actual gas turbine requires 300 KJ/kg of work to quadruple the inlet pressure. The inlet air temperature is 100°C. Determine the compressor efficiency.Answer: C A. 34.56% B. 53.23% C. 60.42% D. 76.34% 7. An ideal gas turbine operates with a pressure ratio of 8:1 and temperature limits of 20°C and 1000°C. The energy input I the high temperature heat exchanger is 200 Kw. Determine the air flow rate.Answer: B A. 560 kr/hr B. 970 kg/hr C. 873 kg/hr D. 453 kg/hr
8. In an air standard Brayton cycle the compressor inlet conditions are 100 kpa and 280°K. The turbine inlet conditions are 1000 Kpa and 1167°K. The turbine produces 11,190Kw. Determine the air flow rate.Answer: A A. 20 kg/s B. 25 kg/s C. 30 kg/s D. 35 kg/s 9. An air standard Brayton cycle has air enters the compressor at 27°C and 100 kpa. The pressure ratio is 10 and the maximum allowable temperature in the cycle is 1350°K. Determine the cycle efficiency per kilogram of air.Answer: A A. 48.20 % B. 51.34 % C. 45.23 % D. 65.23 %
10. An air standard Brayton cycle has air enters the compressor at 27°C and 100 Kpa. The pressure ratio is 10 and maximum allowable temperature is 1350°K. The compressor discharges and the turbine inlet. Determine thermal efficiency of the cycle per kilogram of air.Answer: C A. 34.23% B. 43.23% C. 30.50% D. 27.23% 11. A gas turbine working on an air standard Brayton cycle has air enter into the compressor at atmospheric condition and 22°C. The pressure ratio is 9 and the maximum temperature in the cycle is 1077°C. Compute for the cycle efficiency per kg of air in percent.Answer:D A. 44.85% B. 43.92% C. 41.65% D. 46.67% 12. In a gas turbine unit, air enters the combustion chamber at 550 kpa, 277°C and 43 m/s. The products of combustion leave the combustor at 511 kpa, 1004°C and 140 m/s. Liquid fuelenters with a heating value of 43,000 KJ.kg. For fuel-air ratio of 0.0229, what is the combustir efficiency of the unit in percent?Answer: A A. 79.8% B. 76.5% C. 85.2% D. 69.8% 13. Air compressor of a gas turbine at 100 kpa and 300°K with a volume flow rate of 5 m³/sec. The compressor pressure is 10 and its isentropic efficiency is 85%. At the inlet to the turbine, the pressure is 950 kpa and the temperature is 1400°K. The turbine has an isentropic efficiency of 88% and the exit pressure is 100 Kpa. On the basis of air standard analysis, what is the thermal efficiency of the cycle in percent?Answer: C A. 42.06 B. 60.20 C. 31.89 D. 25.15 HYDRO-ELECTRIC PLANT 1. A hydro-electric power plant consumes 52,650 KW-hrs per annum. Expected flow is 1665 m³/min and overall efficiency is 65%. What is the net head?Answer: D A. 30 m B. 31 m C. 32 m D. 34 m 2. Ina a hydro-electric power the tail water level fixes at 480 m. The net head is 27 m and head loss is 4% of the gross head. What is the head water elevation?Answer: B A. 500.34 m B. 508.12 m C. 456.34 m D. 567.34 m
3. The available flow of water is 25 m³/ sec at 30 m elevation. If a hydro-electric plant is to be installed with turbine efficiency of 85% and generator efficiency of 90%, what maximum power that the plant could generate?Answer: C A. 4658.5 KW B. 3478.5 KW C. 5628.5 KW D. 4756.5 KW 4. For a proposed hydro-electric plant, the tail water and head elevation is 160 m and 195 m, respectively. If available flow is 10 m³/sec and head loss of 5% of water available head. What is the water power?Answer: A A. 3261.8 KW B. 4254.6 KW C. 5874.5 KW D. 2456.5 KW 5. The flow of a river is 20 m³/sec and produces a total brake of 6,000 KW. If it is proposed to install two turbines each has 85% efficiency, what is the available head?Answer: A A. 35 m B. 37 m C. 39 m D. 36 m 6. Two turbines generates a total power of 5000 KW. If one unit is thrice the capacity of the other, find the capacity of smaller unit.Answer: A A. 1250 KW B. 3450 KW C. 2456 KW D. 5763 KW
7. In a hydro-electric plant the brake power is 1800 KW running at 450 rpm and net head of 30 m. Determine the specific speed of the turbine.Answer: D A. 60.29 rpm B. 65.29 rpm C. 75.29 rpm D. 71.29 rpm 8. The specific speed of turbine is 75 rpm and running at 450 rpm. If the head is 20 m and generator efficiency is the maximum power delivered by the generator.Answer: C A. 450.5 KW B. 345.5 KW C. 650.5 KW D. 780.5 KW 9. For a generator running at 300 rpm and 60Hz, find the number of generator poles.Answer: A A. 24 poles
B. 8 poles C. 18 poles D. 20 poles 10. The penstock if hydro-electric plant is 0.5 x 0.5 m with velocity of 5.5 m/sec has a head of 20 m. What is the output of the turbine if the turbine efficiency is 87%?Answer: D A. 845.32 KW B. 789.34 KW C. 654.56 KW D. 234.56 KW 11. A 4m x 0.5m channel has water velocity of 5 m/sec. If the head is 100 m, what is the annual energy produced if overall efficiency is 70%?Answer: C A. 40,456,000 KW-hrs B. 34,456,345 KW-hrs C. 60,154,920 KW-hrs D. 54,867,234 KW-hrs 12. In Francis turbine, the pressure gage leadig to the turbine casing reads 380 Kpa and center of spiral casing is 3 m above the tailrace. If velocity of water entering the turbine is 8 m/sec, what is the net head of the turbine?Answer: D A. 30 m B. 35 m C. 40 m D. 45 m 13. A turbine has a mechanical efficiency of 95%, volumetric efficiency if 97% and total efficiency of 80%, If effective head is 40 m, find the total head.Answer: D A. 48.72 m B. 40.72 m C. 46.72 m D. 34.72 m 14. A Pelton type turbine has 30 m head friction loss of 4.5 m. The coefficienct of friction head loss(from Moorse) is 0.00093 and penstock length of 80 m. What is the penstock diameter? Answer: D A. 1234 mm B. 3476 mm C. 677 mm D. 1686 mm 15. From a height of 65 m water flows at the rate of 0.85 m³/s and is driving a turbine connected to 160rpm generator. If frictional torque is 540 N-m, calculate the turbine brake power.Answer: A A. 533 KW B. 677 KW C. 455 KW D. 488 KW 16. What is the turbine output and delivering 1 m³/sec in a hydro-electric power plant if turbine efficiency is 88%%?Answer: A A. 863.28 KW
B. 734.28 KW C. 167.34 KW D. 492.34 KW 17. In an 8,000 KW hydro-electric plant the over-all efficiency is 88% and the actual power receive by the customer is 110,000 KW-hrs for that day. What is the secondary power could this plant deliver during the entire day?Answer: A A. 58,960 KW-hrs B. 60,960 KW-hrs C. 65,960 KW-hrs D. 70,960 KW-hrs 18. At a proposed hydroelectric plant site, the average elevation of headwater is 600 m, the tailwater elevation is 480 m. The average annual water flow is determined to be equal to the volume flowing through a rectangular channel 4 m wide and 0.5 m deep and average velocity of 5.5 m/sec. Assuming that the plant site can develop if the hydraulic turbine that will be used has an efficiency of 80% and generator efficiency of 92%. Consider a headwork loss of 4% of the available head.Answer: A A. 76,854,851 B. 65,234,556 C. 75,234,455 D. 82,456,677
19. In Maria Christina Hydroelectric Project, the available head is 140 m; the water flow is one cubic meter per second; efficiency of the turbine is 95%; efficiency of the generator is 95%, three phase, 60cycle, voltage delivered is 4160 V. Determine yearly income of the plant if the cost of the generated electric energy is P0.60 per Kwh.Answer: C A. P5,234,567 B. P7,385,678 C. P6,514,778 D. P9,354,677 20. A Pelton type was installed 30 m below the head gate of the penstock. The head loss due to friction is 15% of the given elevation. The length of penstock is 80 m and coefficient of friction is 0.00093. Determine the power output in KW.Answer: D A. 12,273 B. 13,234 C. 12,345 D. 12,493
21. From a height if 65 m, water flows at the rate of 0.85 m³/sec and is driving a water turbine connected to an electric generator revolving at 160 rpm. Calculate the power developed by the turbine in KW if the total resisting torque due to friction is 540 N-m and the velocity of the water leaving the turbine blades is 4.75 m/sec.Answer: B A. 753 B. 523 C. 635 D. 833 22. A proposed hydro-electric power plant has the following data: Elevation of normal headwater surface = 194 m Elevation of normal tailwater surface = 60 m Loss of head due to friction = 6.5 m Turbine discharge at full gate opening = 5 m³/sec Turbine efficiency at rated capacity = 90% Turbine is to be connected to a 60 cycle AC generator. Find the number of poles of the generator?Answer: B A. 6 B. 10 C. 8 D. 12 23. A Francis turbine is installed with a vertical draft tube. The top of the draft is 1 m below the centerline of the spiral casing while the tail race water level is 3 m from the top of the draft tube. There is no velocity of whirl at the top or bottom of the draft tube and leakage are negligible. The elevation of water from the reservoir to the centerline of the turbine casing is 50 m, and water velocity at the inlet is 5 m/sec. Discharge is 2.5 m³/sec, hydraulic efficiency is 86%. Overall efficiency if 83%. Determine the reading of a pressure gage(in psi) if one is installed at the penstock just before the water inlet to the turbine.Answer: A A. 69.35 B. 74.33 C. 56.34 D. 92.45 24. A Francis turbine is installed with a vertical draft tube. The top of the draft is 1 m below the centerline of the spiral casing while the tail race water level is 3 m from the top of the draft tube. There is no velocity of whirl at the top or bottom of the draft tube and leakage are negligible. The elevation of water from the reservoir to the centerline of the turbine casing is 50 m, and water velocity at the inlet is 5 m/sec. Discharge is 2.5 m³/sec, hydraulic efficiency is 86%. Overall efficiency if 83%. Determine the mechanical efficiency of the turbine. Answer: C A. 76.23% B. 83.45% C. 95.51% D. 64.34% 25. A remote community in Mountain Province plans to put up a small hydro-electric plant to service six closely located barangays estimated to consume 52,650,000 KW-hrs per annum. Expected flow if water is 1665 m³/min. The most favorable location for the plant fixes the tail water level at 480 m. The manufacturer of turbine generator set have indicated the following performance data: turbine efficiency 87%; generator efficiency is 92%; loss in head work not exceed 3.8% of
available head. In order to pinpoint the most suitable area for the dam, determine the head water elevation.Answer: D A. 234 m B. 842 m C. 345 m D. 509 m 26. A hydro-electric plant has a 20 MW generator with an efficiency of 96%. The generator is directly coupled to a vertical Francis type hydraulic turbine having an efficiency of 80%. The total gross head on the turbine is 150 m while the loss of head due to friction is 4% of the gross head. The runaway speed is not to exceed 750 rpm. Determine the flow of water through the turbine in cfs.Answer: A A. 651 B. 534 C. 763 D. 827 27. A hydro-electric plant has a 20 MW generator with an efficiency if 96%. The generator is directly coupled to a vertical Francis type hydraulic turbine having an efficiency of 80%. The total gross head on the turbine is 150 m while loss head due to friction is 4% of the gross head. The runaways speed is not to exceed 750 rpm. Determine the rated speed of the turbine.Answer: C A. 300 B. 500 C. 400 D. 600 28. Water flows steadily with a velocity of 3.05 m/s in a horizontal pipe having a diameter of 15.24 cm. At one section of the pipe, the temperature and pressure of the water are 21°C and 689.3 Kpa, respectively. At a distance of 304.8 m downstream. The pressure is 516.9 kpa. What is the friction factor?Answer: C A. 0.134 B. 0.0050 C. 0.0189 D. 0.641 29. A hydroelectric generating unit station is supplied from a reservoir of capacity 6,000,000 m³ at a head of 170 m. Assume hydraulic efficiency of 80% and electrical efficiency 90%. The fall in the reservoir level after a load is 15 MW has been supplied for 3 hours, if the area of the reservoir is 2.5 sq. Km is closet to:Answer: A A. 5.39 cm B. 4.32 cm C. 5.98 cm D. 4.83 cm 30. A pelton wheel is to be designed to rin at 300 rpm under an effectice head of 150 m. The ratio of the nozzle diameter of the pitch circle is 1/12. Assuming efficiency of 84%, what is the size of the wheel in meters. Assume a speed ratio of 0.45.Answer: C A. 1.05 B. 2.00 C. 1.55 D. 2.86
31. A Francis turbine is installed with a vertical draft tube. The total head to the center of the spiral casing at the inlet is 38 m and velocity of water at the inlet is 5 m/sec. The discharge is 2.1 m³/sec. The hydraulic efficiency is 0.87 and overall efficiency is 0.84. The top of draft tube is 1m(water) below the centerline of the spiral casing while the tailrace (water) level is 3m from the top of the draft tube. Neglected velocities of whirl and leakage losses. What is the total head on the turbine in meters?Answer: B A. 34.72 B. 43.27 C. 55.20 D. 48.12 32. A hydro-electric plant discharges water at the rate of 0.75 m³/sec and enters the turbine at 0.35 mps with a pressure of 275 Kpa. Runner inside diameter is 550 mm, speed is 520 rpm and the turbine efficiency is 88%. Find the turbine speed factor.Answer: A A. 0.638 B. 0.386 C. 0.368 D. 0.836 33. A hydraulic turbine receives water from a reservoir at an elevation of 100 meters above it. What is the minimum water kg/s to produce a steady turbine output of 50 Mw?Answer: B A. 50,247 B. 50,968 C. 50,672 D. 50,465 34. A hydro-electric plant having 50 sq. km reservoir area and 100 m head is used to generate power. The energy utilized by the consumers whose load is connected to the power plant during a fivehour period is 13.5 x 106kwh. The overall generation efficiency is 75%. Find the fall in the height of water in the reservoir after the 5-hour period.Answer: B A. 2.13 m B. 1.32 m C. 3.21 m D. 0.53 m 35. A reaction turbine develops 500 bhp. Flow through the turbine is 50cfs. Water enters at 20fps with a 100ft pressure head. The elevation of the turbine above the tail water level is 10 ft. Find the effective head.Answer: D A. 130 ft B. 120 ft C. 110 ft D. 116.2 ft CHIMNEY 1. A boiler uses 2500 kg of coal per hour and air required for the combustion in 16 kg per kg coal. If ash loss is 10%, determine the mass of the gas entering the chimney. Answer: A A. 42,250 kg/hr B. 78,300 kg/hr C. 85,452kg/hr D. 33,800 kg/hr
2. The gas density of chimney is 0.75 kg/m3 and air density of 1.15 kg/m3. If the driving pressure is 0.25 Kpa, determine the height of chimney. Answer: B A. 54.6 m B. 63.7 m C. 74.6 m D. 68.5 m 3. The actual velocity of gas entering in a chimney is 8m/sec. The gas temperature is 25°C and pressure of 98 Kpa with a gas constant of 0.287 KJ/kg-°K. Determine the chimney diameter if mass of gas is 50,000 kg/hr. Answer: D A. 1.57 m B. 1.81 m C. 3.56 m D. 1.39 m 4. A coal fired steam boiler uses 3000 kg of coal per hour. Air required for combustion is 15.5 kg per kg of coal at barometric pressure of 98.2 Kpa. The flue has temperature of 285°C and an average molecular weight of 30. Assuming an ash loss of 11% and allowable gas velocity of 7.5 m/sec, find the diameter of chimney. Answer: C A. 2.0 m B. 1.53 m C. 1.91 m D. 2.5 m 5. A power plant situated at an altitude having an ambient air of 96.53 Kpa and 23.88°C. Flue gases at a rate of 5.0 kg/sec enter the stack at 200°C and leaves at 160°C. The flue gases gravimetric analyses are 18% Co2, 7% O2 and 75% N2. Calculate the height of stack necessary for a driving pressure of 0.20 Kpa. Answer: D A. 59.56 m B. 60. 15 m C. 55. 83 m D. 56.95 m 6. A power plant situated at an altitude having air of 96.53 Kpa and 23.88°C. Flue gases at a rate of 5.0 kg/sec enter the stack at 200°C and leaves at 160°C. The flue gases gravimetric analysis 18% Co2, 7% O2 and 75% N2. Calculate the diameter of stack in meters for a driving pressure of 0.20 Kpa.Answer: B A. 0.50 m B. 0.95 m C. O.60 m D. 1.15 m 7. A steam generator with economizer and air heater has an overall draft loss of 21.78 cm of water. If the stack gases are at 177°C and if the atmosphere is at 101.3 Kpa and 26°C, what theoretical height of stack in meters is needed when no draft fan are used? Assume that the gas constant for the flue gases is the same as that for air. Answer: D A. 565 B. 535 C. 545 D. 550
8. If the actual draft required for a furnace is 6.239 cm of water and the frictional losses in the stack are 15% of the theoretical draft, calculate the required stack height in meters. Assume that the flue gas have an average temperature of 149°C and molecular weight of 30. Assume air temperature of 21°C.Answer: C A. 215 B. 230 C. 220 D. 210 9. A steam boiler plant consumes 9,000 kg of coal per hour and produces 20 kg of dry flue gases per kg of coal fired. Outside air temperature is 32°C, average temperature of the flue gas entering the chimney is 343°C and average temperature of dry flue gas in the chimney is 260°C. The gage fluid density of 994.78 per m3 and the theoretical draft of 2.286 cm of H 2O at the chimney base is needed when the barometric pressure is 760 mm Hg. Determine the height of the chimney.Answer: A A. 46 B. 50 C. 40 D. 56 MACHINE FOUNDATION 1. All heavy machinery should be supported on ________ of sufficient mass and base area to prevent or minimize the transmission of vibrations.Answer: C A. Steel foundation B. Wooden foundations C. Solid foundations D. Soil foundations
2. Foundations mass should be from _______ times the weight of the machinery it is supposed to support.Answer: A A. 3 to 5 B. 5 to 7 C. 4 to 6 D. 1 to 2 3. If the unbalanced inertia forces produced by the machine can be calculated, a mass weight equal to ________ times the forces should be used to dampen vibration.Answer: C A. 2 to 4 B. 5 to 6 C. 10 to 20 D. 10 to 15 4. For stability, the total combined engine, driven equipment, and foundation center of gravity must be kept ________ the foundation’s top.Answer: B A. Above B. Below C. 1 m
D. None of these 5. The machine foundation must have a factor safety of________Answer: C A. 3 B. 4 C. 5 D. 6 6. Foundations should be isolated from floor slabs or building footings at least ________ mm around its perimeter to eliminate transmission vibration.Answer: B A. 20 B. 23 C. 30 D. 35 7. Foundations are preferably built of concrete in the proportion of ________Answer: D A. 1:2:3 B. 1:3:3 C. 1:2:5 D. 1:2:4 8. The machine should not be placed on the foundation until 7 days have elapsed or operated until another ________ days have passed.Answer: B A. 6 B. 7 C. 8 D. 10
9. Concrete foundations should have steel bar reinforcements placed both vertically and horizontally, to avoid ________Answer: B A. Damaging B. Thermal cracking C. Superheating D. Superposing 10. The weight of reinforced steel in a foundation should be from ________ of the weight of the foundation.Answer: A A. ½% to 1% B. 1% to 2% C. 2% to 3% D. 3% to 4% 11. Foundation bolts of specified size should be used and surrounded by a pipe sleeve with an inside diameter of at least ________ times the diameter of the anchor bolt.Answer: C A. 1 B. 2 C. 3 D. 4
12. Foundation bolts length should be at least ________ times the diameter of the anchor bolt.Answer: D A. 12 B. 14 C. 16 D. 18 13. No foundation bolts shall be less than ________ mm diameterAnswer: B A. 10 B. 12 C. 14 D. 16 14. Machine should be leveled by driving wedges between the machine’s base and concrete foundation and with the aid of a ________.Answer: C A. Hose and water B. Try square C. Spirit level D. Level hose 15. Grouting all spaces under the machine bed with a thin mixture of one part cement and ________ part sand.Answer: A A. 1 B. 2 C. 3 D. 4
16. For foundation of stacks, the maximum pressure on the soil is ________ to the pressure due to weight and wind movement.Answer: C A. More than B. Less than C. Equal D. None of the above 17. Guyed stacks seldom exceed 1.83 m diameter and ________ m high.Answer: A A. 32.45 B. 36.34 C. 43.23 D. 30.48 18. The angle between the stacks and the guy wire usually ________ degrees. Answer: B A. 45 B. 60 C. 75 D. 90 19. The angle between wires in a set is ________ degrees for a set of three.Answer: D A. 90
B. 100 C. 110 D. 120 20. The maximum unit pressure of turbine and generator on the reinforced concrete should not exceed ________ kg/cm2.Answer: A A. 17.62 B. 15.34 C. 19.34 D. 21.34 21. For steam turbine foundations the concrete mixture should beAnswer: B A. 1:2:3 B. 1:2:4 C. 1:3:5 D. 1:2:2 22. The steam turbine foundations should be designed to support the machine load plus ________ for impact, condenser load, floor loads and dead loads.Answer: C A. 10% B. 15% C. 25% D. 50% 23. For diesel engines foundation the concrete mixture must be 1:2:4, and the broken stone or gravel must have a size of ________ mm maximum.Answer: C A. 20 B. 40 C. 50 D. 60 24. In pouring a concrete mixture for foundation of diesel engine, it should be poured ________ times.Answer: A A. 1 B. 2 C. 3 D. 4 25. After pouring the foundation of diesel engine, the tops should be covered and wet down twice daily until the forms are removed at the end of the ________ day.Answer: A A. Third of fourth B. Second or third C. Fourth or fifth D. None of these 26. The diesel engine should not be placed on the foundation until 10 days have elapsed, nor operated until after another ________ days.Answer: D A. 7 B. 8 C. 9 D. 10
27. The safe soul bearing pressure of diesel engine foundations isAnswer: B A. 2,600 kg/cm2 B. 4,890 kg/cm2 C. 5,633 kg/cm2 D. 2000 kg/cm2 28. The foundation depth may be taken as good practical rule, to be ________ times the engine stroke.Answer: B A. 2.3 to 4.5 B. 3.2 to 4.2 C. 3.2 to 5.2 D. 5.2 to 6.2 29. Anchor bolts should be embedded in concrete of at least ________ times the bolt diameter.Answer: C A. 10 B. 20 C. 30 D. 40 30. What is the required base area of the foundation to support an engine with specified speed of 1200 rpm and weight of 9,000 kg? Assume bearing capacity of soil as 47.867 kpa. Use e = 0.11Answer: A A. 5.57 m2 B. 8.87 m2 C. 7.75 m2 D. 10.5 m2 31. A foundation measures 3m x 4m x 5m. Find the yd 3 of stone needed for a concrete mixture of 1:2:4.Answer: D A. 65.34 B. 56.45 C. 78.48 D. 69 32. A foundation measures 10ft x 12 ft 15 ft. Find the number of sacks of cement needed for 1:2:4. MixtureAnswer: B A. 300 B. 400 C. 350 D. 450 33. A machine foundation has a trapezoidal cross-sectional with bases of 2m and 3m. The height is 1.5 m and foundation length of 4m. Find the required yd 3 of sand to be used for 1:2:4 mixture.Answer: D A. 7.33 B. 12.4 C. 9.34 D. 8.63
34. A foundation has a weight equal to 4 times the weight of the engine. The safe bearing pressure of soil is 60 kpa and the foundation has a base dimension of 2m x 4m. Find the maximum weight of the engine to be mounted.Answer: C A. 8,234 kg B. 6,455 kg C. 9,736 kg D. 12,344 kg 35. A rectangular foundation cross-section has a bed plate dimension of 4 ft x 8 ft. The uniform clearance on each side is 1 ft. The height of foundation is 2.5 ft. If the weight of the steel bar reinforcements needed is ½% of weight of foundation, find the weight of steel bars. Use concrete density of 2400 kg/m3.Answer: A A. 51 kg B. 45 kg C. 65 kg D. 76 kg HEAT TRANSFER 1. A 15 cm thick wall has a thermal conductivity of 5W /m-°K. If inside and outside surface temperature of the wall are 200°C and 20°C, respectively. Determine the heat transmitted.Answer: A A. 5.67 KW/m2 B. 4.68 KW/m2 C. 8.87 KW/m2 D. 6.87 KW/m2 2. Two walls of cold storage plant are composed of an insulating material (l = 0.25 KJ/hr-m-°C), 100 mm thick at the outer layer and material (l = 3.5 KJ/hr-m-°C), 15 cm thick at inner layer. If the surface temperature at cold side is 30°C and hot side is 250°C, find the heat transmitted per square meter.Answer: A A. 0.138 KW/m2 B. 0.450 KW/m2 C. 0.025 KW/m2 D. 0.065 KW/m2 3. Sea water for cooling enters a condenser at 27°C and leaves at 37°C. The condenser temperature is 45°C, what is the log mean temperature difference?Answer: B A. 50.65°C B. 12.33°C C. 37.82°C D. 80.54°C 4. Determine the thermal conductivity of a material that uses a 2 m 2 test panel, 25 mm thick with a temperature difference of 10.8°F between the surfaces. During the 5 hours test period, the heat transmitted is 200 KJ.Answer: C A. 0.045 W/m-°K B. 0.560 W/m-°K C. 0.023 W/m-°K D. 0.370 W/m-°K
5. A steam pipe having a surface temperature of 200 °C passes through a room where the temperature is 27°C. The outside diameter of pipe is 80 mm and emissivity factor is 0.8 Calculate the radiated heat loss for 3 m pipe length.Answer: A A. 1434.47 W B. 2746.35 W C. 2756.57 W D. 3546.45 W 6. A counter flow heat exchanger is designed to heat fuel oil from 30°C to 90°C while the heating fluid enters at 140°C at 105°C. Determine the arithmetic mean temperature difference.Answer: B A. 72.5°C B. 62.5°C C. 45.5°C D. 67.5°C 7. A heat exchanger has an overall coefficient of heat transfer of 0.50 KW/m 2-°C. Heat loss is 11 KW and the mean temperature difference is 15°C. What is the heat transfer are in ft 2?Answer: D A. 51.80 ft2 B. 37.30 ft2 C. 56.80 ft2 D. 15.80 ft2
8. Brine enters a circulating brine cooler at the rate of 60 m 3/hr at -10°C and leaves at -16°C. Specific heat of brine is 1.072 KJ/kg-°K and specific gravity of 1.1. Determine the tons of refrigeration.Answer: C A. 53.5 TR B. 65.3TR C. 33.5 TR D. 44.5 TR 9. A heat exchanger has a hot gas temperature of 300°C and surface conductance on hot side is 200 W/m2-°K. If heat transmitted is 1000 W/m2, what is the surface temperature on the wall at hot side?Answer: A A. 295°C B. 465°C C. 234°C D. 354°C 10. A heat exchanger is to be designed for the following specifications: Hot gas temperature, 1145°C Cold gas temperature is 45°C Unit surface conductance on the hot side, 230 W/m2-°K Unit surface conductance on the cold side, 290 W/m2-°K Thermal conductivity of the metal wall, 115 W/m-°K Find the maximum thickness of metal wall between the hot gas and cold gas, so that the maximum temperature of the wall does not exceed 545°C.Answer: C A. 10 mm
B. 30mm C. 20mm D. 40mm 11. An uninsulated steam pipe passes through a room in which the air and walls are at 25°C. The outside diameter of the pipe is 70 mm, and its surface temperature and emissivity are 200°C and 0.80, respectively. If the coefficient associated with free convection heat transfer from the surface to the air is 15 W/m2-°K, what is the rate of heat loss from the surface per unit length of pipe? Answer: A A. 998 w/m2 B. 872 w/m2 C. 762 w/m2 D. 422 w/m2 12. A turbo-charged, 16 cylinder, Vee-type diesel engine has an air consumption of 3,000 kg/hr per cylinder at rated load and speed. This air is drawn in through a filter by a centrifugal compressor directly connected to the exhaust gas turbine. The temperature of the air from the compressor is 145°C and a counter flow air cooler reduces the air temperature to 45°C before it goes to the engine suction header. Cooling water enters air cooler at 30°C and leaves at 38°C. Calculate the log mean temperature difference.Answer: A A. 47°C B. 87°C C. 34°C D. 65°C 13. A turbo-charged, 16 cylinder, Vee type diesel engine has an air consumption of 3,000 kg/her per cylinder at rated load and speed. This air is drawn in through a filter by a centrifugal compressor directly connected to the exhaust gas turbine. The temperature of the air from the compressor is 145°C and a counter flow air cooler reduces the air temperature to 45°C before it goes to the engine suction header. Cooling water enters air cooler at 30°C and leaves at 38°C. Calculate the quantity of cooling water in m 3/hr required to cool the total requirements of the engine at rated load and speed.Answer: A A. 144 B. 136 C. 123 D. 165 14. An oil heater heats 100 kg per minute of oil from 35°C to 100°C in a counter flow heat exchanger. The average specific heat of the oil is 2.5KJ/kg-°C. Exhaust gases used for heating enter the heater with an average specific heat of 1 KJ/kg-°C, a mass flow rate of 250 kg/min and an initial temperature of 200°C. The overall heat transfer coefficient is 75 W/m 2-°C. Determine heating surface in square meters.Answer: D A. 30 B. 63 C. 40 D. 36 15. A surface condenser serving a 50,000 KW steam turbo-generator unit receives exhaust steam at the rate of 196,000 kg/hr. Vacuum in condenser is 702 mm Hg. Sea water for cooling enters at 29.5°C and leaves at 37.5°C. For steam turbine condensed as heat given up to cooling water. Calculate logarithmic mean temperature difference in °F.Answer: C A. 10
B. 14 C. 12 D. 16 16. A surface condenser serving a 50,000 KW steam turbo-generator unit receives exhaust steam at the rate of 196,000 kg/hr. Vacuum in condenser is 702 mm Hg. Sea water for cooling enters at 29.5°C and leaves at 37.5°C. For steam turbine condenser design, manufacturers consider 950 Btu/lb of steam turbine condensed as heat given up to cooling water. Calculate the required quantity of cooling water in cubic meters per hour.Answer: D A. 10,374 B. 12,445 C. 11,345 D. 13,509 17. Calculate the energy transfer rate across 6” wall of firebrick with a temperature differences across the wall of 50°C. The thermal conductivity of the firebrick is 0.95 Btu/hr-ft-°F at the temperature interest.Answer: B A. 285 W/m2 B. 369 W/m2 C. 112 W/m2 D. 429 W/m2
18. Water is flowing in a pipe with radius of 25.4 cm at a velocity of 5m/sec at the temperature in the pipe. The density and viscosity of the water are as follows: density = 997.9 kg/sec, viscosity = 1.131 Pa-s. What is the Reynolds Number for this situation?Answer: A A. 2241 B. 96.2 C. 3100 D. 1140 19. The hot combustion gases of a furnace are separated from the ambient air and its surrounding, which are at 25°C, by a brick wall 0.15 m thick. The brick has a thermal conductivity of 1.2 W/m-°K and surface emissivity of 0.8. Under steady state conditions and outer surface temperature of 100°C is measured. Free convection heat transfer to the air adjoining this surface is characterized by a convection coefficient of 20W/m2-°K. What is the brick inner surface temperature in °C?Answer: B A. 623.7 B. 352.5 C. 461.4 D. 256.3 20. Steam initially saturated at 2.05 Mpa, passes through a 10.10 cm standard steel pipe for a total distance of 152 m. The steam line is insulated with a 5.08 cm thickness of 85% magnesia. For an ambient temperature of 22°C, what is the quality of the steam which arises at its destination if the mass flow rate is 0.125 kg steam per second? Properties of steam: Pressure = 2.05 Temperature = 213.67 Enthalpy: hf = 914.52 hfg = 1885.5 hg = 28000.0
k for 85% magnesia = 0.069 W/m-°K fo for still air = 9.36 W/m-°KAnswer: A A. 93% B. 98% C. 84% D. 76% 21. Compute the amount of condensate formed during 10 minutes warm-up of 150 meter pipe conveys the saturated steam with enthalpy vaporization h fg = 1,947.8 LJ/kg.The minimum external temperature of pipe is 2°C. The final temperature of pipe is 195°C. The specific heat of pipe material is 0.6 KJ/kg-°C. The specific weight is 28 kg/m.Answer: C A. 249.69 kg B. 982.45 kg C. 294.54 kg D. 423.45 kg 22. What is the heat transfer in the glass surface area of 0.7 m 2 having an inside temperature (room) of 23°C and 13°C outside temperature (surrounding). The thickness of glass surface is 0.0007 m. The thermal conductivity is 1.8 W/m-°K.Answer: D A. 5.8 kw B. 3.6 kw C. 6.2 kw D. 2.34 kw
AIR COMPRESSOR 1. An air compressor takes air at 100 Kpa and discharges to 600 Kpa. If the volume flow of discharge is 1.2 m3/sec, determine the capacity of air compressor.Answer: A A. 4.32 m3/sec B. 3.33 m3/sec C. 6.85 m3/sec D. 7.42m3/sec 2. The discharge pressure of an air compressor is 5 times the suction pressure. If volume flow of suction is 0.1 m3/sec, what is the compressor power assuming n = 1.35 and suction pressure is 98 Kpa?Answer: B A. 21.67 KW B. 19.57 KW C. 25.87 KW D. 10.45 KW 3. A 10 Hp motor is used to drive an air compressor. The compressor efficiency is 75%. Determine the compressor work.Answer: A A. 6.0 KW B. 6.5 KW C. 7.6 KW D. 5.6 KW
4. The initial condition of air in an air compressor is 98 Kpa and 27°C and discharges air at 400 Kpa. The bore and stroke are 355 mm and 381 mm, respectively with percent clearance of 5% running at 300 rpm. Find the volume of air at suction.Answer: C A. 600 m3/hr B. 610 m3/hr C. 620 m3/hr D. 630 m3/hr 5. An air compressor has a suction volume of 0.25 m 3/sec at 97 Kpa and discharges to 650 Kpa. How much power saved by the compressor if there are two stages?Answer: A A. 8.27 KW B. 6.54 KW C. 3.86 KW D. 10.0 KW 6. The suction condition of an air is 98 Kpa, 27°C and 0.2 m 3/sec. If the surrounding air is 100 Kpa and 20°C, determine the free air capacity in m3/sec.Answer: B A. 0.15 B. 0.19 C. 0.25 D. 0.23
7. A 355 mm x 381 mm air compressor has a piston displacement of 0.1885 m 3/sec. Determine the operating speed of the compressor.Answer: B A. 250 rpm B. 300 rpm C. 350 rpm D. 600 rpm 8. Determine the percent clearance of an air compressor having 87% volumetric efficiency and compressor air pressure to be thrice the suction pressure.Answer: D A. 5% B. 7% C. 15% D. 11% 9. The compressor work of an air compressor is 100 KW. If the piston speed is 15 m 3/min, determine the mean effective pressure.Answer: C A. 200 Kpa B. 300 Kpa C. 400 Kpa D. 600 Kpa 10. A double acting air compressor has 16 in x 7 in, 600 rpm has what volume displacement? Answer: D A. 688 ft3/min B. 755 ft3/min C. 488 ft3/min D. 977 ft3/min
11. A two-stage air compressor has a suction pressure of 14 psi and discharge pressure of 130 psig. What is the intercooler pressure in Kpag.Answer: A A. 209 Kpag B. 600 Kpag C. 477 Kpag D. 300 Kpag 12. A two stage air compressor has an intercooler pressure of 3 kg/cm2. What is the discharge pressure if suction pressure is 1kg/cm2?Answer: B A. 3 kg/cm2 B. 9kg/cm2 C. 23 kg/cm2 D. 15 kg/cm2 13. The piston speed of an air compressor is 140 m/min and has a volume displacement of 0.2m 3/sec. Determine the diameter of compressor cylinder.Answer: C A. 500 mm B. 358 mm C. 467 mm D. 246 mm
14. An air compressor piston displacement is 5000 cm 3 when operates at 900 rpm and volumetric efficiency of 75%/ Determine the mass flow of air standard density.Answer: B A. 365.3 kg/hr B. 243.5 kg/hr C. 386 kg/hr D. 465.2 kg/hr 15. A two-stage compressor air at 100 Kpa and 22°C discharges to 690 Kpa. If intercooler intake is 105°C, determine the value of n.Answer: C A. 1.400 B. 1.358 C. 1.345 D. 1.288 16. The piston displacement of a double acting compressor running at 300 rpm is 0.4 m 3/sec. If bore and stroke are unity, determine the length of stroke.Answer: C A. 350 mm B. 380 mm C. 371 mm D. 400 mm 17. An air compressor takes air at 97 Kpa at the rate of 0.5 m 3/sec and discharge 500 Kpa. If power input to the compressor is 120 KW, determine the heat loss in the compressor.Answer: B A. 26.5 KW B. 18.55 KW C. 30.45 KW
D. 22.36 KW 18. A single acting air compressor has a volumetric efficiency of 87%, operates at 500 rpm. It takes in air at 100 Kpa and 30°C and discharges it at 600 Kpa. The air handled is 6m 3/min measured at discharge condition. If compression is isentropic, find mean effective pressure in Kpa.Answer: D A. 182 B. 983 C. 198 D. 204 19. A single acting reciprocating air compressor has a clearance volume of 10%. Air is received at 90 Kpa and 90.3°C and is discharged at 600 Kpa. The compression and expansion are polytropic with n – 1.28. The pressure drop is 5 Kpa at suction port and 10 Kpa at discharge port. The compressor piston displacement is 500 cm3 when operating 900 rpm. Determine the mass of compressed air in kg/hr.Answer: A A. 16.76 B. 20.45 C. 98.33 D. 28.23
20. A single acting air compressor operates at 150 rpm with an initial condition of air at 97.9 Kpa and 27°C and discharges the air at 379 Kpa to a cylindrical tank. The bore and stroke are 355 mm and 381 mm respectively, with 5% clearance. If the surrounding air is at 100 Kpa and 20°C while the compression and expansion process are PV1.3 = C, determine air capacity, m3/secAnswer: A A. 0.0919 B. 2.13 C. 1.23 D. 4.23 21. The piston displacement of a double acting compressor is 0.358 m 3/sec, delivers gas from 101. 325 Kpa and 300 °K to 675 Kpa at the rate of 0.166 m 3/sec at 150 rpm. Value of n for compression and expansion is 1.33. Find the compressor percent clearance.Answer: A A. 16.96 B. 14.23 C. 12.34 D. 18.44 22. The piston displacement of a double acting compressor is 0.358 m 3/sec, delivers gas from 101. 325 Kpa and 300°K to 675 Kpa at the rate of 0.166 m 3/sec at 150 rpm. Value of n for compression and expansion is 1.33. Find the bore and stroke assuming bore = stroke.Answer: D A. 300 mm B. 400mm C. 350 mm D. 450 mm 23. A 2-stage, double acting, L-type air compressor 16” x 10” x 7”, 600 rpm, has a free air unloader at each end for capacity control. It is driven through V-belts by a 150 Hp electric motor, 460 V, 3
phase, 60 Hz, 1200 rpm. Barometric pressure is 125 psi gage. Calculate piston displacement in m3/hrAnswer: C A. 562 m3/hr B. 762 m3/hr C. 649 m3/hr, 1661 m3/hr D. 833 m3/hr, 724 m3/hr 24. A two-cylinder single-acting air compressor is directly coupled to an electric motor running at 1000 rpm. Other data are as follows: Size of each cylinder = 150 mm x 200 mm Clearance volume = 10% of displacement Exponent (n) for both compression and re-expansion process = 1.6 Air constant = 1.4 Air molecular mass M = 29 Calculate the volume rate of air delivery in terms of standard air for a delivery pressure 8 times ambient pressure under ambient air conditions of 300 °K and 1 bar.Answer: D A. 2 m3/hr B. 4m3/hr C. 3m3/hr D. 5m3/hr 25. A two stage compressor with first stage piston displacement of 94390 cm 3/sec is driven by a motor. Motor output is 35 Hp, suction temperature is 22°C, volumetric efficiency is 85%. Mechanical efficiency is 95%, the intercooler pressure is 30 psi gage. Air temperature in and out of the intercooler are 105°C and 44°C. Final discharge pressure is 100 psi gage, suction estimated 14.5 psi. Find the compression efficiency.Answer: A A. 77.60% B. 63.34% C. 87.34% D. 98.23% 26. An air compressor is to compress 8.5 m 3/min from 98.56 Kpa to 985.6 Kpa. Assuming conditions are ideal, and with n = 1.3, what will be the saving in work due to two staging?Answer: C A. Zero B. 4.6 KW C. 5.6 KW D. 3.5 KW 27. A single stage air compressor handles 0.454 m 3/sec of atmospheric pressure, 27°C air, and delivers it to a receiver at 652.75 Kpa. Its volumetric efficiency on an isothermal basis is 0.85 and its mechanical efficiency is 0.90. If it operates at 350 rpm, what power in KW is required to drive it?Answer: B A. 95 B. 112 C. 120 D. 100 28. A two stage compressor receives 0.50 kg/s of air at 120 kpa and 300°K and delivers it at 7 Mpa. Find the heat transferred in the intercooler.Answer: A A. 118.14 kw B. 124.55 kw
C. 233.34 kw D. 187.34 kw 29. An air compressor is tested and it is found that the electric motor used 37.3 kw when the compressor handled 0.189 m3/s of air at 101.4 kpa and 300 °K and discharged it at 377.1 kpa. Determine the adiabatic efficiency.Answer: C A. 67.34% B. 76.34% C. 81.89% D. 92.34% 30. An air compressor is tested and it is found that the electric motor used 37.6 kw when the compressor handled 0.189 m 3/s of air at 101.4 kpa and 300°K and discharged it at 377.1 kpa. Determine the isothermal efficiency.Answer: A A. 67.34% B. 76.34% C. 81.89% D. 67.48%
31. Calculate the volumetric efficiency of a single-cylinder, double acting compressor with a bore and stroke of 0.45 x 0.45 m. The compressor is tested at 15- rpm and found to deliver gas from 101.3 kpa and 300°K to 675 kpa at a rate of 0.166 m 3/s when n- 1.33 for expansion and compression process.Answer: A A. 46.39% B. 56.23% C. 48.34% D. 74.23% 32. A reciprocating compressor with a 3% clearance receives air at 100 kpa and 300°K and discharges it at 1.0 Mpa. The expansion and compression are polytropic with n = 1.25. There is a 5% pressure drop through the inlet and outlet valves. Find the volumetric efficiency.Answer: B A. 76.23% B. 82.50% C. 98.33% D. 65.33% 33. A reciprocating compressor has a 5% clearance with a bore and stroke of 25 x 30 cm. The compressor operates at 50 rpm. The air enters the cylinder at 27°C and 96 kpa and discharges at 2000 kpa. If n = 1.3, determine the compressor power.Answer: C A. 2.34 kw B. 18.45 kw C. 27.25 kw D. 34.32 kw 34. A water-jacketed air compressor handles 0.143 m3/s air entering at 96.5 kpa and 21°C and leaving at 480 kpa and 132°C; 10.9 kg/h of cooling water enters the jacket at 15°C and leaves at 21°C. Determine the compressor power.Answer: A
A. B. C. D.
26.163 kw 17.23 kw 34.44 kw 19.33 kw
35. A 2-stage compressor operates between constant pressure limits of 98.6 kpa and 1.103 Mpa. The swept volume of the low pressure piston is 0.142 m3. Due to failure of the cooling water supply to the intercooler, air is passed to the high pressure cylinder without reduction in temperature. Using PV1.2 = C, determine the percentage increase in power.Answer: C A. 26 B. 21 C. 11 D. 16 36. An ideal-single stage air compressor without clearance takes in air at a100 kpa with a temperature of 16°C and delivered at 413 Kpa after isentropic compression. What is the discharge work done b the compressor in KJ/kg? A. -59.22 B. -52.43 C. -54.75 D. -56.13 Answer: -145 KJ/kg (no answer in the given choices) PUMPS 1. A double suction centrifugal pumps delivers 70 ft 3/sec of water at a head of 12 m and running at 1250 rpm. What is the specific speed of the pump?Answer: D A. 5014 rpm B. 5453 rpm C. 2345 rpm D. 9968 rpm 2. The pump centerline of a centrifugal pump is located 2.5 m above from the high tide level. The sea water varies two meters from high tide to low tide level. If friction loss at the suction is 0.8 m, determine the total suction head.Answer: A A. 5.30 m B. 2.30 m C. 6.30 m D. 8.23 m 3. A centrifugal pump requires 40 ft head to deliver water from low level to higher level. If pump speed is 1600 rpm, determine the impeller diameter of the centrifugal pump. Answer: A A. 185 mm B. 160 mm C. 154 mm D. 176 mm 4. The suction pressure of a pump reads 2 in. of mercury vacuum and discharge pressure reads 130 psi is used to deliver 100 gpm of water with specific volume of 0.0163 ft 3/lb. Determine the pump work.Answer: B
A. B. C. D.
4.6 KW 5.7 KW 7.4 KW 9.4 KW
5. A pump is to deliver 150 gpm of water at ahead of 120 m. If pump efficiency is 70%, what is the horsepower rating of motor required to drive the pump?Answer: D A. 40.44 Hp B. 25.66 Hp C. 38.44 Hp D. 21.33 Hp 6. A motor is used to d rive a pump having an efficiency of 85% and 70 % respectively. What is the combined efficiency of pump and motor?Answer: A A. 59.50% B. 61.50% C. 62.50% D. 65.50%
7. In a boiler feed pump, the enthalpy at the entrance is 765 KJ/kg. If pump has a head of 900 m, what is the exit enthalpy of the pump.Answer: C A. 897 KJ/kg B. 465 KJ/kg C. 774 KJ/kg D. 864 KJ/kg 8. A submersible pump delivers 350 gpm of water to a height of 5 ft from the ground. The pump was installed 120 ft below the ground level and a draw down of 8 ft during the operation. If water level is 25 ft above the pump, determine the pump power.Answer: C A. 7.13 KW B. 4.86 KW C. 7.24 KW D. 864 KW 9. Determine the number of stages needed for a centrifugal pump if it is used to deliver 400 gal/min of water and pump power of 15 Hp. Each impeller develops a head of 38 ft. Answer: B A. 6 B. 4 C. 8 D. 7 10. A boiler feed pump receives 50 li/sec of water with specific volume of 0.00112 m 3/kg at ahead of 750 m. What is the power output of driving motor if pump efficiency is 65%? Answer: A A. 505.32 KW B. 643.54 KW
C. 785.56 KW D. 356.45 KW 11. What power can a boiler feed pump can deliver a mass of 35 kg/s water at a head of 500 m? Answer: D A. 356.56 KW B. 354.54 KW C. 456.64 KW D. 171.67 KW 12. A pump running at 100 rpm delivers water against a head of 30 m. IF pump speed will increase to 120 rpm, what is the increase in head?Answer: B A. 43.2 m B. 13.2 m C. 34.6 m D. 56.3 m 13. A pump is used to deliver 50 li/sec of sea water at a speed of 120 rpm. If speed will increase to 135 rpm, determine the increase in pump capacity.Answer: D A. 56.25 li/sec B. 34.56 li/sec C. 87.54li/sec D. 6.260 li/sec 14. A 15 KW motor running at 350 rpm is used to drive a pump. If speed will be changed to 370 rpm, what is the increase in power?Answer: A A. 2.72 KW B. 17.72 KW C. 56.45 KW D. 5.67 KW 15. A certain pump is used to deliver 150 gpm of water having a density of 61.2 lb/ft 3. The suction and discharge gage reads 4 in Hg vacuum and 25 psi, repectively, The discharge gage is 2 ft above the suction gage. What is the brake power of the motor if pump efficiency is 75%?Answer: A A. 3.24 Hp B. 2.67 Hp C. 5.45 Hp D. 6.89 Hp 16. The discharge pipe of a pump is 400 mm in diameter delivers 0.5 m 3/sec of water to a building which maintains a pressure of 100 Kpa at a height of 30 m above the reservoir. If equivalent head is 2m, what power must be furnished by the pump?Answer: A A. 211 KW B. 480 KW C. 340 KW D. 240 KW 17. A centrifugal pump is designed for 1800 rpm and head of 61m. Determine the speed of impeller if diameter is reduces from 305 mm to 254 mm.Answer: C A. 1000 rpm
B. 1250 rpm C. 1500 rpm D. 1600 rpm 18. Water from a reservoir A 10 m elevation is drawn by a motor driven pump to an upper reservoir B at 72m elevation. Suction and discharge head loss are 0.15m, respectively. For discharge rate of 15li/sec, find the power input to the motor if overall efficiency is 65%.Answer: C A. 12.65 KW B. 23.54 KW C. 14.17 KW D. 45.35 KW 19. The elevation of suction reservoir is 5m above the pump centerline and delivers to 85m elevation tank which maintain 150 Kpa. If 1.5m3/sec of water is used to deliver a total head of 3m, determine the power needed by the pump.Answer: A A. 1446 KW B. 2546 KW C. 4675 KW D. 3456 KW
20. Water from a reservoir is pumped over a hill through a pipe 900 mm in diameter and a pressure of one kg/cm2 is maintained at the pipe discharge where the pipe is 85m from the pump centerline. The pump has a positive suction head of 5m. Pumping rate of the pump at 1000 rpm is 1.5 m3/sec. Friction losses is equivalent to 3m of head loss. What amount of energy must be furnished by the pump in KW?Answer: A A. 1372 kw B. 1523 kw C. 1234 kw D. 1723 kw 21. Water from a reservoir is pumped over a hill through a pipe 450 mm in diameter and a pressure of 1 kg/cm2 is maintained at the summit. Water discharge is 30m above the reservoir. The quantity pumped is 0.5 m3/sec. Frictional losses in the discharge and suction pipe and pump is equivalent to 1.5m head loss. The speed of the pump is 800 rpm what amount of energy must be furnished by the pump in KW?Answer: B A. 202 B. 206 C. 204 D. 208 22. Water from an open reservoir A at 8m elevation is drawn by a motor-driven pump to an open reservoir B at 70m elevation. The inside diameter of the suction pipe is 200mm and 150mm for the discharge pipe. The suction line has a loss of head three times that of the velocity head in the 200 mm pipe. The discharge line has a loss of head twenty times that of the velocity head in the discharge pipeline. The pump centerline is at 4m. Overall efficiency of the system is 78%. For a discharge rate of 10li/sec, find the power input to the motor and the pressure gage reading installed just at the outlet and inlet of the pump in Kpag.Answer: D A. 2.34 kw
B. 5.45 kw C. 6.59 kw D. 7.84 kw 23. A pump is to deliver 80 gpm of water at 140°F with a discharge pressure of 150 psig. Suction pressure indicates 2 inches of mercury vacuum. The diameter of suction and discharge pipes are 5 inches, respectively. The pump has an efficiency of 70%, while the motor efficiency is 80%. Determine power input to the drive motor.Answer: D A. 7.23 kw B. 2.34 kw C. 8.34 kw D. 9.39 kw 24. Determine the water horsepower and the mechanical efficiency of a centrifugal water pump which has an input of 3.5 Hp if the pump has an 8 inches nominal size suction and 6 inches nominal size discharge if it handles 150 gpm of water at 150°F. The suction line gage shows 4” Hg vacuum and the discharge gage shows 26 psi. The discharge gage is located 2 feet above the center of the discharge pipe line and pump inlet and discharge lines are at the same elevation.Answer: A A. 2.52 hp B. 6.33 hp C. 4.23 hp D. 8.34 hp 25. A boiler feed pump receives 40 liters per second at 4 Mpa and 180°C. It operates against a total head of 900 m with an efficiency of 60%. Determine the enthalpy leaving the pump in KJ/kgAnswer: B A. 783.45 B. 773.57 C. 756.23 D. 765.23 26. A boiler feed pump receives 40 liters per second at 180°C. It operates against a total head of 900 m with an efficiency of 60%. Determine power output of the driving motor in KW.Answer: D A. 453.23 B. 623.34 C. 983.45 D. 523.27 27. A boiler feed pump receives 40 liters per second at 180°C. It operates against a total head of 900m with an efficiency of 60%. Determine discharge pressure in Kpa for a suction pressure of 4 Mpa.Answer: A A. 11,850 kpa B. 13,455 kpa C. 12,566 kpa D. 14,233 kpa 28. A boiler feed pump receives 45 li/sec of water at 190°C and enthalpy of 839.33 KJ/kg. It operates against a head of 952m with efficiency of 70%. Estimate the water leaving
temperature assuming that the temperature rise as due to the inefficiency of the input energyAnswer: A A. 191°C B. 143°C C. 123°C D. 165°C 29. A submersible, multi-stage, centrifugal deep well pump 260 gpm capacity is installed in a well 27 feet below the static water level. Drawdown when pumping at rated capacity is 10 feet. The pump delivers the water into a 25,000 gallons capacity overhead storage tank. Total discharge head developed by pump, including friction in piping is 243 feet. Calculate brake horsepower required to drive the pump if pump efficiency is 70%.Answer: C A. 31.31 B. 41.41 C. 21.21 D. 51.51
30. A submersible, multi-stage, centrifugal deep well pump 260 gpm capacity is installed in a well 27 feet below the static water level and running at 3450 rpm. Drawdown when pumping at rated capacity overhead storage tank. Total discharge head developed by pump, including friction in piping is 243 feet. Calculate the diameter of the impeller of this pump in inches if each impeller diameter developed a head of 38 ft.Answer: A A. 3.28 B. 5.33 C. 4.23 D. 6.34 31. A double suction, single stage, centrifugal pump delivers 900 m 3/hr of sea water(SG = 1.03) from a source where the water level varies two meters from high tide to low tide level. The pump centerline is located 2.6 meters above the surface of the water at high tide level. The pump discharges into a surface condenser, 3m above pump centerline. Loss of head due to friction in suction pipe is 0.8m and that in the discharge side is 3m. Pump is directly coupled to a 1750 rpm, 460 V, 3 phase, 60 Hz motor. Calculate the specific speed of pump in rpm.Answer: B A. 3131 rpm B. 5151 rpm C. 4141 rpm D. 6161 rpm 32. A pump driven by an electric motor moves 25 gal/min of water from reservoir A to reservoir B, lifting the water to a total of 245 feet. The efficiency of the pump and motor are 64% and 84% respectively. What size of motor(HP) is required?Answer: B A. Hp B. 3 Hp C. 4 Hp D. 7.5 Hp
33. Water is pumped at 1m3/sec to an elevation of 5m through a flexible hose using a 100% efficiency pump rated at 100 KW. Using the same length of hose, what size of motor is needed to pump 1 m3/sec of water to a tank with no elevation gain? In both cases both ends of hose are at atmospheric pressure. Neglect kinetic energy.Answer: A A. 51 KW B. 18 KW C. 43 KW D. 22 KW 34. A vacuum pump is used to drain a flooded mine shaft of 20°C water. The pump pressure of water at this temperature is 2.34 Kpa. The pump is incapable of lifting the water higher than 10.16m. What is the atmospheric pressure?Answer: D A. 109 B. 112 C. 98 D. 101.9
35. It is desired to deliver 5 gpm at a head of 640m in a single stage pump having specific speed not to exceed 40. If the speed is not to exceed 1352 rpm, how many stages are required? Answer: D A. 3 B. 4 C. 5 D. 2 36. The rate of flow of water in a pump installation is 60.6 kg/sec. The intake static gage is located 1.22m below the pump center line and reads 68.95 Kpa gage; the discharge static gage is 0.61m below the pump centerline and reads 344.76 Kpa gage. The gages are located close to the pump as much as possible. The areas of the intake and discharge pipes are 0.093 m2 and 0.069 m2, respectively. The pump efficiency is 70%. Take density of water equals 1000 kg/m3. What is the hydraulic power in KW?Answer: A A. 17.0 B. 24.5 C. 31.9 D. 15.2 37. Water in rural areas is often extracted from underground water source whose free surface is 60m below ground level. The water is to be raised 5m above the ground by a pump. The diameter of the pipe is 10 cm at the inlet and 15 cm at the exit. Neglecting any heat interaction with the surroundings and frictional heating effects, what is the necessary power input to the pump for a steady flow of water at the rate of 15 li/sec in KW if pump efficiency is 85%?Answer: D A. 9.54 B. 5.343 C. 7.82 D. 11.23
38. A pump lifts water at a rate of 283 lps from a lake and force it into a tank 8m above the level of the water at a pressure of 137 kpa. What is the power required in kilowatts.Answer: C A. 71 B. 41 C. 61 D. 51 39. A pump receives 8kg/s of water at 220 Kpa and 110°C and discharges it at 1100 kpa. Compute for the power required in kilowatts.Answer: C A. 8.126 B. 5.082 C. 7.041 D. 6.104 40. A fuel pump is delivering 10 gallons per minute of oil with a specific gravity of 0.83. The total head is 9.14m, find how much energy does the pump consumes in KJ per hour. Answer: A A. 169 B. 19 C. 189 D. 179 41. A pump discharges 150 liters per second of water to a height of 75 meters. If the efficiency is 75% and the speed of the pump is 1800 rpm, what is the torque in N-m to which the drive shaft is subjected?Answer: B A. 771 B. 781 C. 791 D. 681 42. A pump with a 400 mm diameter suction and a 350 mm diameter discharge pipe is to deliver 20,000 liters per minute of 15.6°C water. Calculate the pump head in meters if suction gage is 7.5cm below pump centerline and reads 127mm Hg vacuum and discharge gage is 45cm above the pump centerline and reads 75 kpa.Answer: D A. 15 m B. 5 m C. 20 m D. 10 m 43. A centrifugal pump delivers 300,000 liters per hour of water to a pressurized tank whose pressure is 280 kpa. The source of water is 5m below the pump. The diameter of the suction pipe is 300mm and the discharge pipe is 250mm. Calculate the kw rating of the driving motor assuming the pump efficiency to be 72%.Answer: D A. 41.75 kw B. 35.75 kw C. 43.26 kw D. 38.16kw
44. A centrifugal pump delivers 80 liters per second of water on test. Suction gage reads 10 MM Hg vacuum and 1.2 meters below pump centerline. Power input is 70 kw. Find the total dynamic head in meters. Answer: A A. 66 B. 60 C. 62 D. 64 45. A pump delivers 500 gpm of water against a total head of 200 ft and operating at 1770 rpm. Changes have increased the total head to 375 ft. At what rpm should the pump be operated to achieve the new head at the same efficiency?Answer: D A. 2800 rpm B. 3600 rpm C. 3434 rpm D. 2424 rpm
FANS AND BLOWERS 1. A fan whose static efficiency is 40% has a capacity of 60,000 ft 3/hr at 60°F and barometer of 30 in Hg and gives a static pressure of 2 in of water column on full delivery. What size of electric motor should be used to drive the fan?Answer: B A. ½ Hp B. 1 Hp C. 2 Hp D. 1 ½ Hp 2. A fan draws 1.42 m3 per second of air at a static pressure of 2/54 cm water through a duct 300mm diameter and discharges it through a duct of 275mm diameter. Determine the static fan efficiency if total fan mechanical is 70% and air is measured at 25°C and 760 mm Hg.Answer: A A. 50.11% B. 54.34% C. 65.37% D. 45.34% 3. Find the air horsepower of an industrial fan that delivers 25 m 3/s of air through a 900mm by 1200mm outlet. Static pressure is 127mm of water gage and air density is 1.18 kg/m3.Answer: B A. 65.35 Hp B. 52.35 Hp C. 60.35 Hp D. 70.35 Hp
4. A boiler requires 90,000 m 3/hr of standard air. The mechanical efficiency of fan to be installed is 65%. Determine the size of driving motor assuming fan can deliver a total pressure of 150mm of water gage.Answer: A A. 56.6 KW B. 78.5 KW C. 45.5 KW D. 23.5 KW 5. At 1.2 kg/m3 air density a fan develops a brake power of 100 KW. It operates at 98 Kpa and 32°C with the same speed, what is the new brake power of the fan?Answer: D A. 68.4 KW B. 36.7 KW C. 67.5 KW D. 93.3 KW 6. A fan has a suction pressure of 30mm water vacuum with air velocity of 3m/sec. The discharge has 150 mm of water gage and discharge velocity of 7m/sec. Determine the total head of fan if air density is 1.2 kg/m3.Answer: B A. 150 m B. 152 m C. 154 m D. 156 m 7. A 50 KW motor is used to drive a fan that has a total head of 110 m. If fan efficiency is 70%, what is the maximum capacity of the fan using standard density of air?Answer: A A. 27 m3/sec B. 29 m3/sec C. 31 m3/sec D. 33 m3/sec 8. A fan using standard air condition can develop a static pressure head of 310 mm water gage. If fan will operate 93°C and 735 mm of Hg, find the new static pressure required.Answer: C A. 150 mm water gage B. 180 mm water gage C. 241 mm water gage D. 456 mm water gage 9. The total head of fan is 185m and has a static pressure of 210 mm of water gage, what is the velocity of air flowing if density of air is 1.15 kg/m3?Answer: A A. 6.85 m/sec B. 3.45 m/sec C. 4.75 m/sec D. 8.54 m/sec 10. The volume flow of air delivered by fan is 20 m 3/sec and 180 mm water gage. The density of air is 1.185 kg/m3 and motor power needed to drive the fan is 44 KW. What is the fan efficiency?Answer: B A. 70.26% B. 80.26% C. 75.26% D. 90.26%
11. A fan is listed as having the following performances with standard air: Volume discharged = 120 m3/sec Speed = 7.0 rps Static pressure = 310 mm water gage Brake power required = 620 KW The system duct will remain the same and the fan will discharge the same volume of 120 m3/sec of air at 93°C and a barometric pressure of 735 mm Hg when its speed is 7.0 rps. Find the brake power input and the static pressure required.Answer: C A. 231 mm water B. 251 mm water C. 241 mm water D. 261 mm water 12. Air enters a fan through a duct at velocity of 6.3 m/s and an inlet static pressure of 2.5 cm of water less than atmospheric pressure. The air leaves the fan through a duct a t a velocity of 11.24 m/s and a discharge static pressure of 7.62 cm of water above the atmospheric pressure. If the specific weight of the air is 1.20 kg/m3 and the fan delivers 9.45 m 3/sec, what is the fan efficiency when the power input to the fan is 12.75 KW at the coupling?Answer: A A. 71.81% B. 91.23% C. 81.34% D. 61.34% 13. A fan delivers 4.7 m3/sec at a static pressure of 5.08 cm of water when operating at a speed of 400 rpm. The power input required is 2.863 KW. If 7.05 m 3/sec are desired in the same fan and installation, find the pressure in cm of water.Answer: C A. 7.62 B. 17.14 C. 11.43 D. 5.08 14. A fan described in a manufacturer’s table is rated to deliver 500 m 3/min at a static pressure (gage) of 254 cm of water when running at 250 rpm and requiring 3.6 KW. If the fan speed is changed to 305 rpm and air handled were at 65% instead of standard 21°C, find the power in KW.Answer: D A. 3.82 B. 5.08 C. 4.66 D. 5.68 15. Air is flowing in a duct with velocity of 7.62 m/s and static pressure of 2.16 cm water gauge. The duct diameter is 1.22m, the barometric pressure 99.4 Kpa and the gage fluid temperature and air temperature are 30°C. What is the total pressure against which the fan will operate in cm of water?Answer: B A. 3.25 B. 2.5 C. 3.75 D. 1.25 FLUID
1. A perfectventure with throat diameter of 1.8 inches is placed horizontally in a pipe with a 5 in inside diameter. Eighty (80) lb of water flow through the pipe each second. What is the difference between the pipe and venturi throat static pressure?Answer: B A. 29.9 lb/in2 B. 34.8 lb/in2 C. 5020 lb/in2 D. 72.3 lb/in2 2. What is the expected head loss per mile of a closed circular pipe (17 in inside diameter), friction factor of 0.03 when 3300 of water flow under pressure?Answer: A A. 38 ft B. 3.580 ft C. 0.007 ft D. 0.64 ft
3. A rigid container is closed at one end and measure 8 in diameter by 12 in long. The container is held vertically and is slowly moved downward until the pressure in the container is 15.5 psia. What will be the depth of the water surface measure from the free water surface? Answer: A A. 22 in B. 9.2 in C. 12 in D. 9.8 in 4. The pressure drop across a turbine is 25 psi. The flow rate is 55 gallons per minute. Calculate the power output of the turbine.Answer: A A. 0.802 hp B. 0.41 hp C. 1.05 hp D. 2.54 hp 5. Two tubes are mounted to the roof of a car. One tube points to the front of the car while the other point to the rear. The tubes are connected to a manometer filled with fluid of specific gravity. 0.60. When the height difference is 2 inches, what is the car’s speed?Answer: C A. 46 mph B. 43.8 mph C. 50 mph D. 62 mph 6. What is the density of a stone that weighs 19.9 lb (88 N) in air and 12.4 lb (55 N) in water? Answer: A A. 2,651.2 kg/m3 B. 2,612.5 kg/m3 C. 2,578.2 kg/m3
D. 26,700 kg/m3 7. The flow rate of water through a cast iron pipe is 5000 GPM. The pipe is 1 ft and the coefficient of friction f = 0.0173. What is the pressure drop over a 100 ft length of pipe? Answer: 5.404 ft of water A. 337.26 lb/in2 B. 21.078 lb/in2 C. 337.26 lb/in2 D. 23.780 lb/in2 8. Pressure drop across a turbine is 30 psi, the flow rate is 60 gpm. Calculate the power output of the turbine.Answer: B A. 0.41 hp B. 1.05 hp C. 6.30 hp D. 2.54 hp
9. The fluid in a manometer tube is 60% water and 40% alcohol (SG = 0.8). What is the monometer fluid height difference if a 6.2 psi pressure is applied across the tow ends of a manometer?Answer: D A. 15.5 in B. 186 in C. 36 in D. 215 in 10. An air bubble rises from the bottom of a well where the temperature is 25°C, to the surface where the temperature is 27°C. Find the percent increase in volume of the bubble if the depth of the well is 5m. Atmospheric pressure is 101.528 Kpa.Answer:A A. 49.3 B. 31.3 C. 56.7 D. 38.6 11. An empty, open can is 30 cm high with a 10-cm diameter. The can, with the open end down, is pushed under water with a density of 1000 kg/m3. Find the water level in the can when the top of the can is 50 cm below the surface.Answer: B A. 17.20 cm B. 2.12 cm C. 4.20 cm D. 5.87 cm 12. A 24 inches long rod floats vertically in water. It has a 1 sq. in. cross section and has a specific gravity of 0.6. What length L is submerged?Answer: A A. 14.4 in B. 2.4 in C. 9.6 in D. 18.0 in
13. Flow of water taking over in a pipe having a velocity of 10 m/s. Determine the velocity head of the water.Answer: B A. 50.1 m B. 5.1 m C. 8.2 m D. 100m 14. The length of pipe is 168 meters. If the pressure drop is 50 Kpa for every 30 meters, what is the total pressure drop?Answer: C A. 260 kpa B. 300 kpa C. 280 kpa D. 100 kpa 15. Hydraulic efficiency 85%, find Q in li/s. Power developed 10,500 kw under head of 320 m.Answer: A A. 3935 B. 3452 C. 3271 D. 3623 16. A cylindrical pipe with water flowing downward at 0.02 m 3/s having top diameter of 0.08, bottom diameter of 0.04 and height of 1.5 m. Find the pressure between the pipes. Answer: A A. 104 kpa B. 87 kpa C. 120 kpa D. 143 kpa 17. A fluid that has a velocity of 18 m/s will have an equivalent head of?Answer: A A. 16.51 m B. 12.44 m C. 18.34 m D. 10.34 m 18. Determine the size of pipe which will deliver 5 liters of medium oil (v = 6.10 x 10-6 m 2/s) assuming laminar flow conditions.Answer: A A. 522 mm B. 454 mm C. 550 mm D. 650 mm 19. The power available in a jet having a cross-sectional area of 0.005 m 2 with a velocity of 25.80 m/s.Answer: C A. 34 kw B. 49 kw C. 43 kw D. 23 kw 20. The type of flow occupying in a 30 cm diameter pipe which water flows at a velocity of 2.10 m/s. Use v = 1.13 x 10-6 m2/s for water.Answer: A
A. B. C. D.
Turbulent Constant Laminar None of these
21. A man weighing 64 kg causes a flat area 30 cm thick to be just fully submerged in a sea water (SG = 1.03). Neglecting weight the area must be:Answer:D A. 0.085 m2 B. 0.756 m2 C. 0.172 m2 D. 0.062 m2 22. What force is m/sAnswer: B A. B. C. D.
exerted by water jet 50 mm diameter if it strikes a wall at the rate of 15 342 N 442 N 764 N 563 N
23. A 300 mm x 75 mm venture meter is inserted in a 300 mm diameter pipeline where water flows at 55 liters/s. Neglecting friction loss, compute the drop in pressure head from the inlet to the throat.Answer: A A. 8 m B. 10 m C. 6 m D. 12 m 24. A jet of water 50 mm diameter with a velocity of 35 m/s is being discharged in a horizontal direction from a nozzle mounted on a fire truck. The force required to hold the nozzle stationary is:Answer: B A. 1.34 KN B. 2.40 KN C. 4.23 KN D. 3.23 KN 25. An open storage vessel has 3 m of oil (SG = 0.82) and 6 m of water. The pressure at the bottom is:Answer: C A. 45 kpa B. 65 kpa C. 83 kpa D. 92 kpa 26. A 200 mm diameter pipe gradually reduces to a 100 mm diameter. The 200 mm diameter pipe is connected to another pipe having a pressure of 600 kpa horizontally with a flow of 0.04 m3/s. Find the pressure at the 100 mm diameter.Answer: A A. 588 kpa B. 642 kpa C. 566 kpa D. 598 kpa
27. A 200 mm diameter pipe discharges water at the rate of 200 li/s. Point 1 on the pipe has a pressure of 280 kpa and 3.4 m below point 1 is point 2 with a pressure of 300 kpa. Compute the head loss between points 1 and 2.Answer: D A. 4.2 m B. 2.5 m C. 6.3 m D. 1.4 m 28. An object weighs 90 N in air and when immersed in water weighs 50 N. Compute the specific gravity of the object. A. 1.25 B. 3.25 C. 2.25 D. 4.25
REFRIGERATION 1. The enthalpy at the entrance of the condenser is 1660 KJ/kg and exit is 315 KJ/kg. The compressor has an enthalpy of 1450 KJ/kg at entrance. Determine the COP.Answer: C A. 4.2 B. 2.0 C. 5.4 D. 6.0 2. An evaporator has a temperature of 3°C with entrance enthalpy of 352.75 KJ/kg. At 3, h f = 319.56 KJ/kg and hg = 642.45 KJ/kg. Find the quality after expansion.Answer: D A. 16.27% B. 21.48% C. 15.67% D. 10.27% 3. The refrigerating effect of 100 tons refrigeration is 117 KJ/kg. Determine the mass flow of refrigerant.Answer: C A. 1kg/sec B. 2kg/sec C. 3 kg/sec D. 4 kg/sec 4. The density of R-12 refrigerant at compressor suction is 19.81 kg/m 3. For mass flow rate of 2 kg/sec, determine the volume flow at suction.Answer: A A. 0.10 m3/sec B. 0.25 m3/sec C. 0.30 m3/sec D. 0.40 m3/sec 5. A 100 ton refrigeration system has a COP of 5. Determine the compressor horsepower.
Answer: A A. B. C. D.
94.26 Hp 86.76 Hp 86.76 Hp 65.65 Hp
6. A 90 ton refrigeration system has a compressor input of 0.97 KW per ton refrigeration and COP of 5. What is the efficiency of the compressor?Answer: A A. 72.49% B. 90.42% C. 56.34% D. 83.33% 7. A 90 ton refrigeration system has a compressor input of 0.97 KW per ton refrigeration. If compressor efficiency is 75%, determine the heat rejected from the condenser.Answer: D A. 350 KW B. 260 KW C. 500 KW D. 382 KW 8. The mass flow rate of refrigerant entering the compressor is 0.25 kg/s and the change of enthalpy between the inlet and outlet is 320 KJ/kg. If 134 Hp motor is used to drive the compressor, determine the heat loss from the compressor.Answer: B A. 15 KW B. 20 KW C. 25 KW D. 30 KW 9. A 100 ton refrigeration system is used to produce chilled water from 22°C to 2°C. Determine the volume flow of water in li/sec.Answer: C A. 3.0 B. 3.5 C. 4.2 D. 5.5 10. An industrial plant requires cooling 120 gal/min of water from 20°C to 5°C. Determine the tons of refrigeration required. Answer: D A. 100 TR B. 130 TR C. 145 TR D. 135 TR 11. The difference in temperature between the water leaving the evaporator and evaporator temperature is 5°C. If the temperature of water leaving is 32°F, what is the evaporator temperature?Answer: D A. 0°C B. -2°C C. -4°C D. -5°C
12. The heat rejected from condenser is 300 KW. The water required to cool the refrigerant is 5 li/sec. Determine the temperature of water leaving the condenser if water enters at 25°C.Answer: D A. 30°C B. 35°C C. 45.33°C D. 39.33°C 13. The mass flow of refrigerant entering the compressor is 0.1 kg/sec with change of enthalpy of 400 KJ/kg. For compressor efficiency of 70% and motor efficiency of 80%, find the electrical energy needed for one day.Answer: D A. 1524 KW-hr B. 1685 KW-hr C. 3456 KW-hr D. 1714 KW-hr
14. An 80 ton refrigeration system requires 105 KW from VECO. If motor compressor efficiency is 60%, find the COP.Answer: C A. 5.84 B. 3.56 C. 4.46 D. 3.78 15. The change of enthalpy between the inlet and outlet of evaporator is 1000 KJ/kg and mass flow of refrigerant is 12 kg/min. What is the capacity of plant?Answer: C A. 15 TR B. 25 TR C. 57 TR D. 60 TR 16. The mass flow of water entering the condenser is 10 kg/sec. If the temperature difference between inlet and outlet temperature is 18°F, determine the heat rejected from the condenser.Answer: B A. 400 KW B. 419 KW C. 500 KW D. 324 KW 17. The change of enthalpy in the condenser is 1500 KJ/kg. The temperature change of water is 8°C and the refrigerant flow is 0.13 kg/sec. Determine the gpm of water required for cooling.Answer: A A. 92 gpm B. 88 gpm C. 45 gpm D. 67 gpm
18. The heat rejected from the condenser is 200 KW. The mass flow of water entering is 5 kg/sec at 23°C. If the temperature between the condenser cooling water outlet and condenser temperature is 5°C, what is the condenser temp?Answer: D A. 30.56°C B. 39.94°C C. 35.78°C D. 37.67°C 19. The heat from the condenser of Carnot refrigeration is 6000 KJ/min. The minimum and maximum temperature is -25°C and 72°C respectively. Determine the horsepower required to drive the compressor. Answer: C A. 30 Hp B. 35 Hp C. 38 Hp D. 42 Hp
20. The temperature difference between the minimum and maximum temperature of Carnot cycle is 50°C. What is the minimum temperature if COP is 5.5Answer: A A. 0.31°C B. 2°C C. 3°C D. 5°C 21. The power required to drive the compressor in Carnot refrigeration is 50 Hp. It operates between -5°C and 40°C. Determine the tons of refrigeration.Answer: D A. 57 TR B. 34 TR C. 55TR D. 63 TR 22. Determine the heat to be removed from one ton of water at 26°C to an ice at -6°C.Answer: B A. 215,765 KJ B. 413,956 KJ C. 345,654 KJ D. 834,582 KJ 23. The heat required to remove from beef 110 kg is 36,437 which will be cooled from 20°C to -18°C. The specific heat above freezing is 3.23 KJ/kg-°K and latent heat of fusion is 233 KJ/kg. If specific heat below freezing is 1.68 KJ/kg-°K, find the freezing temperature.Answer: B A. -5.65°C B. -2.19°C C. -1.01°C D. -10°C
24. A refrigeration compressor has a specific volume of 0.0482 m3/kg entrance and 0.017 m 3/kg at exit. If volumetric efficiency is 90%, determine the percent clearance of the compressor.Answer: A A. 5.45% B. 6.35% C. 10% D. 12% 25. Milk must be received and cooled from 80°F to 38°F in 5 hrs. If 4000 gallons of fresh milk received having SG of 1.03 and cp = 0.935 Btu per lb-°F, find the refrigeration capacity.Answer: C A. 20 TR B. 30TR C. 22.5TR D. 34.6 TR
26. An air-conditioning plant with a capacity of 400 KW of refrigeration has an evaporating and condensing temperature of 3°C and 37°C respectively. If it uses Refrigerant 12, what will be the mass of flash gas per kg of refrigerant circulated?Answer: A A. 21.80% B. 12.45% C. 14.56% D. 18.34% 27. An air-conditioning plant with a capacity of 400 KW of refrigeration has an evaporating and condensing temperature of 3°C and 37°C respectively. If it uses Refrigerant 12, what is the volumetric rate of flow under suction condition?Answer: C A. 0.272 m3/s B. 0.453 m3/s C. 0.172 m3/s D. 0.243 m3/s 28. An air-conditioning system of a high rise building has a capacity of 350 KW of refrigeration; uses R-12. The evaporator and condenser temperature are 0°C and 35°C, respectively. Determine work of compression in KW.Answer: B A. 34 KW B. 52 KW C. 43 KW D. 65 KW 29. A vapor compression refrigeration system has a 30 KW motor driving the compressor. The compressor inlet pressure and temperature are 64.17 Kpa and 20°C respectively and discharge pressure of 960 Kpa. Saturated liquid enters the expansion valve. Using Freon 12 as refrigerant, determine the capacity of the unit in tons of refrigeration.Answer: D A. 16.15 tons ref.
B. 20 tons ref. C. 25 tons ref. D. 17.14 tons ref 30. A simple vapor compression cycle develops 15 tons of refrigeration using ammonia as refrigerant and operating at condensing temperature of 24°C and evaporating temperature of -18°C and assuming compression are isentropic and that the gas leaving the condenser is saturated, find the power per ton.Answer: D A. 0.333 kw/ton B. 0.533 kw/ton C. 0.452 kw/ton D. 0.702 kw/ton
31. A vapor compression refrigeration system is designed to have a capacity of 100 tons of refrigeration. It produces chilled water from 22°C to 2°C. Its actual coefficient of performance is 5.96 and 35% of the power supplied to the compressor is lost in the form of friction and cylinder cooling losses. Determine size of the electric motor required to drive the compressor in kilowatts.Answer: A A. 92.31 kw B. 76.24 kw C. 87.23 kw D. 98.23 kw 32. A vapor compression refrigeration system is designed to have a capacity of 100 tons of refrigeration. It produces chilled water from 22°C to 2°C. Its actual coefficient of performance is 5.86 and 35% of the power supplied to the compressor is lost in the form of friction and cylinder cooling losses. Determine the condenser cooling water required in kg/sec for a temperature rise of 10°C.Answer: A A. 9.83 B. 7.45 C. 12.23 D. 4.34 33. A belt driven compressor is used in a refrigeration system that will cool 10 li/sec of water from 13°C to 1°C. The belt efficiency is 98%, motor efficiency is 85%, and the input of the compressor is 0.7 KW/ton of refrigeration. Find the actual coefficient of performance if overall efficiency is 65%.Answer: D A. 2.34 B. 4.43 C. 3.45 D. 6.44
34. A belt driven compressor is used in a refrigeration system that will cool 10 li/sec of water from 13°C to 1°C. The belt efficiency is 98%, motor efficiency is 85%, and the input of compressor is 0.7 KW/ton of refrigeration. Find the mass flow rate of condenser cooling water warmed from 21°C to 32°C if overall efficiency is 65%.Answer: B A. 10.34 kg/s B. 12.60 kg/s C. 23.23 kg/s D. 15.34 kg/s 35. Calculate the bore in mm of a single-acting, 6 cylinder ammonia compressor running at 1200 rpm to compress 700 kg/hr refrigerant which vaporized at -15°C, given the following Bore and stroke = Unity Volumetric Efficiency = 70% Specific volume of NH3 = 8.15 ft3/lb at 5°FAnswer: C A. 110 mm B. 106 mm C. 114 mm D. 124 mm
36. An ammonia compressor operates at an evaporator pressure of 316 Kpa and a condenser pressure of 1514.2 Kpa. The refrigerant is subcooled 5 degrees and is superheated 8 degrees. A twin cylinder compressor with a bore to stroke ratio of 0.85 is to be used at 1200 rpm. The mechanical efficiency is 78%. For a load of 87.5 kw, determine the bore and stroke for 5% clearance.Answer: C A. 123.44 mm B. 109.23 mm C. 117.40 mm, 99.79 mm D. 234.23 mm, 86.79 mm 37. In a certain refrigeration system for a low temperature application, a two stage operation is desirable which employs ammonia system that serves a 30 ton evaporator at -30°C. The system uses direct contact cascade condenser, and the condenser temperature is 40°C. Find the total power required in kw.Answer: B A. 23.43 kw B. 35.37 kw C. 28.34 kw D. 45.23 kw 38. A refrigeration system operates on the reversed Carnot cycle. The minimum and maximum temperatures are -25°C and 72°C, respectively. If the heat rejected to the condenser is 6000 KJ/min, draw the T-S diagram and find power input required.Answer: D A. 20.34 kw B. 54.33 kw C. 13.45 kw D. 28.12 kw 39. A refrigerating system operates on the reversed Carnot cycle. The highest temperature of the refrigerant in the system is 120°F and the lower temperature is 10°F. The capacity is to be 20 tons. Determine the heat rejected from the system in Btu/minAnswer: A
A. B. C. D.
4936 5634 3432 7421
40. An ice plant produces 20 tons of ice per day at -15°C from water at 25°C. If miscellaneous losses are 12% of the freezing and chilling load, calculate the refrigeration capacity of the plant in tons of refrigeration. Answer: C A. 21.35 B. 43.12 C. 31.5 D. 36.3 41. Fish weighing 11,000 kg with a temperature of 20°C is brought to a cold storage and which shall be cooled to -10°C in 11 hours. Find the required plant refrigerating capacity in tons of refrigeration if the specific heat of fish is 0.7 above freezing and 0.3 below freezing point which is -3°C. The latent heat of freezing is 55.5 Kcal/kg.Answer: B A. 21.3 B. 24.38 C. 28.34 D. 32.12 42. Compute the heat to be removed from 110 kg of lean beef if it were to be cooled form 20°C to 4°C, after which it is to be frozen and cooled to -18°C. Specific heat above freezing is given as 3.23 KJ/kg°C and below freezing as 1.68 KG/kg-°C. Freezing point is -2.2°C and latent heat of fusion is 233 KJ/kg.Answer: C A. 32,455 KJ B. 23,455 KJ C. 36,437.5 KJ D. 54,233.2 KJ 43. Magnolia Dairy products plant must cool 4000 gallons of fresh milk received from the farm per day from an initial temperature of 80°F to a temperature of 38°C in 5 hours. If the density of milk is 8.6 lbs/gallon, specific gravity is 1.03, and specific heat is 0.935 how much brine must be circulated if the change in temperature is 15°F, specific gravity is 1.182, and specific heat is 0.729?Answer: A A. 41.77 gpm B. 54.22 gpm C. 34.11 gpm D. 65.23 gpm 44. A mass of ice at 25°F is needed to cool 250 pound of vegetables in a bunker, for 24 hours. The initial temperature of the vegetables is assumed to be 85°F. It is also assumed that the average temperature inside the bunker is 45°F, within the 24-hour period. If the heat gained per hour in the bunker is 30% of the heat removed to cool the vegetables from 85°F to 45°F, what would be the required mass of ice?Answer: D Specific heat of ice = 0.463 Specific heat of vegetables = 0.80 Specific heat of water = 1.01 Heat of fusion of ice = 144 Btu/lb A. 34.56 lbs B. 74.23 lbs
C. 43.23 lbs D. 64.8 lbs 45. A 10 ton ice plant using ammonia refrigerant operates between evaporator and condenser temperature of -20°C and 35°C respectively. The ice plant is to produce ice at -12°C from water at 30°C in 24 hours. Assuming losses to be 18 of the heat absorbed from water, determine the power required by the compressor.Answer: B A. 21.23 kw B. 16.79 kw C. 56.32 kw D. 43.32 kw 46. An ideal vapor compression refrigeration cycle requires 2.5 KW to power the compressor. You have found the following data for the cycle: the enthalpy at condenser entrance = 203 KJ/kg, exit = 55; evaporator entrance = 55 KJ/kg, exit = 178. If mass flow rate of the refrigerant is 0.10 kg/sec, then the coefficient of performance of the refrigeration cycle is most nearly:Answer: D A. 592 B. 59.2 C. 5.92 D. 4.92 47. A Freon – 12 waste water system operating at a 5°C suction temperature and a 40°C condensing temperature has an evaporator load of 5 tons. If the condenser is selected for a 7°C water temperature rise, how many gpm must be circulated through the condenser? The following enthalpies have been found: condenser entrance = 377 KJ/kg, exit = 238.5; evaporator entrance = 238.5 KJ/kg, exit = 353.6.Answer: A A. 11.46 gpm B. 15.23 gpm C. 13.45 gpm D. 23.22 gpm 48. A refrigeration system operates on an ideal vapor-compression using Refrigerant-12 with an evaporator temperature of -30°C and a condenser exit temperature of 49.3°C and requires a 74.6 KW motor to drive the compressor. What is the capacity of the refrigerator in tons of refrigeration? Enthalpy of condenser entrance = 362 KJ/kg, exit = 248.15; evaporator entrance = 248.15, exit = 338.14.Answer: A A. 43.5 B. 34.5 C. 21.3 D. 18.2 49. Liquid ammonia at a temperature of 26°C is available at the expansion valve. The temperature of the vaporizing ammonia in the evaporator is 2°C. Find the percentage of liquid vaporized while flowing through the expansion valveAnswer: A Temperature Pressure (°C) (Kpa) hf hfg hg 2°C 462.49 190.4 1255.2 1445.6 26°C 1033.97 303.6 1162.0 1465.6 A. 9.02 B. 90.98
C. 91.08 D. 8.92 50. A 140 mm x 140 mm single effect, twin-cylinder single acting Freon-12 compressor with a refrigeration capacity of 40 kw operates between a discharge pressure of 1300 kpa and a suction pressure of 350 kpa. The speed of the compressor is 600 rpm. If the discharge pressure shall be raised to 1400 kpa, at what speed (rpm) should the compressor be run to produce the same refrigeration capacity and assuming the volumetric efficiency to remain the same?Answer: C A. 610 B. 614 C. 622 D. 630
51. A refrigeration system using R-22 has a capacity of 320 kw of refrigeration. The evaporating temperature is minus 10 degrees C and the condensing temperature is 40°C. Calculate the fraction of vapor in the mixture before the evaporator.Answer: A Properties of R-22 are: At -10°C hg = 401.60 KJ/kg ht = 188.426 KJ/kg At 40°C hf = 249.686 KJ/kg A. 0.287 B. 0.315 C. 0.245 D. 0.227 52. What is the coefficient of a vapor compression refrigeration system having the following data: Enthalpy entering the compression is 181.79; enthalpy after compression work is 207.3 KJ/kg. After condensation the enthalpy is 58.2 and the throttled from 0.19 Mpa to 0.18 Mpa.Answer: C A. 5.8 B. 3.2 C. 4.84 D. 5.6 53. A refrigeration system having a 22 kw capacity needs 7.8 compressor. Find the COP of the systemAnswer: C A. 3.12 B. 4.62 C. 3.78 D. 6.34 AIR CONDITIONING
1. When 100 kg/min of outside air at 32°C dry bulb and 200 kg/min recirculated air at 22°C dry bulb are mixed with an air conditioning system, the resulting dry bulb temperature will be:Answer: A A. 25.33°C B. 35.44°C C. 46.33°C D. 26.88°C 2. The amount of water carried by air in a cooling tower is 15 lb/min. The change in humidity ratio in outlet and inlet is 0.025 lb/lb. Determine the volume flow of air needed if specific volume is 15 ft3/lb.Answer: B A. 6000 ft3/min B. 7800 ft3/min C. 7500 ft3/min D. 5000 ft3/min
3. The change of enthalpy of air in a cooling tower is 35 Btu/lb and the mass flow of air is 453.17 lb/min. Water enters the tower at the rate of 50 gpm and 115 °F. Determine the exit temperature. Answer: D A. 45°F B. 55°F C. 65°F D. 77°F 4. The change of enthalpy in air conditioning unit is 10 Btu/lb. The mass of supply air is 150,000 lb/hr. What is the conditioner capacity?Answer: C A. 125 TR B. 100 TR C. 150 TR D. 200 TR 5. Recirculated air of 8 kg/sec with 53 KJ/kg enthalpy and outside air of 2 kg/sec with 90 KJ/kg enthalpy enters the conditioning unit. Determine the air conditioning capacity if supply enthalpy to conditioned space is 42 KJ/kg.Answer: D A. 154 KW B. 164 KW C. 174 KW D. 184 KW 6. Outside air of an air conditioning system is 25% of recirculated air. Determine the mass of outside air if mass of supply air is 15 kg/sec.Answer: C A. 1 kg/sec B. 2 kg/sec C. 3 kg/sec D. 4 kg/sec 7. The sensible heat load and latent heat load in an air conditioning system is 120 KW and 47 KW, respectively. What is the sensible heat factor?Answer: D A. 65.34%
B. 29.45% C. 76.54% D. 71.86% 8. The total heat load and latent heat load of theater is 150 KW and 60 KW, respectively. Supply air is at 15°C and has a mass of 9 kg/sec. Determine the temperature to be maintained in the theater.Answer: B A. 20°C B. 25°C C. 30°C D. 35°C 9. A cooling tower has an efficiency of 65%. Water enters the tower at 55°C. The wet bulb temperature of surrounding air is 27°C. What is the temperature of water leaving the tower? Answer: A A. 36.8°C B. 44.5°C C. 46.9°C D. 30.4°C 10. The change of temperature entering the cooling tower and wet bulb temperature of surrounding air is 25°C and efficiency is 65%. If mass of water leaving the tower is 10 kg/sec, determine the heat carried by air.Answer: C A. 720 KW B. 540 KW C. 680 KW D. 700 KW 11. The approach and efficiency of cooling tower is 10°C and 60%, respectively. If temperature of water leaving the tower is 37°C, what is the temperature of water entering?Answer: B A. 46°C B. 52°C C. 68°C D. 48°C 12. A cooling tower is used to cool a jacket water loss from the engine. The heat generated by fuel is 2500 KW and cooling loss is 30%. If temperature range of the tower is 15°C. Determine the mass flow of water entering the tower.Answer: A A. 12 kg/sec B. 14 kg/sec C. 16 kg/sec D. 18 kg/sec 13. A dryer is to deliver 1000 kg/hr of cassava with 2% moisture and 20% moisture in the feed. Determine the mass of air required if change in humidity ratio is 0.0165.Answer: C A. 3.57 kg/sec B. 4.67 kg/sec C. 3.79 kg/sec D. 5.36 kg/sec
14. The moisture removed from a material is 250 lb/hr and change of humidity ratio in dryer is 0.0175. Determine the fan capacity if specific volume of air entering is 35 ft 3/lb.Answer: C A. 400,000 ft3/hr B. 450,000 ft3/hr C. 500,000 ft3/hr D. 550,000 ft3/hr 15. The change of enthalpy in a heating chamber of dryer is 25 Btu and the mass of air supplied is 30,000 lb/hr. What is the heat supplied by heater?Answer: D A. 560 KW B. 450 KW C. 350 KW D. 220 KW
16. Water at 55°C is cooled in a cooling tower which has an efficiency of 65%. The temperature of the surrounding air is 32°C dry bulb and 70% relative humidity. The heat dissipated from the condenser is 2,300,000 KJ/hr. Find the capacity in liters per second of the pump used in the cooling water. Answer: A A. 8.55 B. 7.34 C. 6.34 D. 9.23 17. Fifty gallons per minute of water enters a cooling tower at 115°F. Atmospheric air at 60°F and 55% relative humidity enters the tower at 6,000 cfm and leaves at 90°F saturated. Determine the volume of water that leaves the tower in gpm.Answer: B A. 32.34 B. 48.62 C. 34.23 D. 65.33 18. Fifty gallons per minute of water enters a cooling tower at 115°F. Atmospheric air at 60°F and 55% relative humidity enters the tower at 6,000 cfm and leaves at 90°F saturated. Determine the exit temperature of water, °FAnswer: C A. 56.33 B. 65.33 C. 76.61 D. 45.34 19. An atmospheric cooling tower is to provide for the jacket water of a four stroke, 800 KW diesel generators with useful output of 34% and cooling loss of 30%. The cooling tower efficiency is 60% at a temperature of approach of 10°C. If ambient air has a relative humidity of 70% and dry bulb temperature of 32°C, determine the cooling water supplied to the diesel engine in li/hr. Generator efficiency is 97%.Answer: A A. 41,713 B. 45,232
C. 43,345 D. 47,234 20. 250,000 kg/hr of water at 35°C enters a cooling tower where it is to be cooled to 17.5°C. The energy is to be exchanged with atmospheric air entering the unit at 15°C and leaving the unit at 30°C. The air enters at 30% RH and leaves at 85% RH. If all process are assumed to occur at atmospheric pressure, determine the percentage of total water flow that is make up water.Answer: D A. 2.44% B. 8.34% C. 3.94% D. 2.22%
21. An auditorium is to be maintained at a temperature of 26°C dry bulb and 50% RH. Air is to be supplied at a temperature not lower than 15°C dry bulb. The sensible heat gain is 110 Kw and the latent heat gain is 37.5 KW. Take ventilating air as 25% by weight of the air from the room, and is at 35°C dry bulb and 60% RH. Determine the refrigeration capacity in tons? Answer: C A. 43.45 B. 54.23 C. 63.28 D. 76.34 22. An assembly hall was to have an air conditioning unit installed which would be maintained at 26°C dry bulb and at 50% RH. The unit delivers air at 15°C dry bulb temperature and the calculated sensible heat load is 150 kw and latent heat is 51.3 KW. Twenty percent by weight of extracted air is made up of outside air at 34°C dry bulb and 60% RH while 80% is extracted by the air conditioner from the assembly hall. Determine the air conditioner’s refrigeration capacity in tons refrigeration and its ventilation load in KW.Answer: A A. 83.22, 132 B. 75.34, 412 C. 56.23, 45.32 D. 54.23, 83.23 23. An air conditioned heater is to be maintained at 80°F dry bulb temperature and 50% RH. The calculated total sensible heat load in the theater is 620,000 Btu/hr, and the latent heat load is 210,000 Btu/hr. The air mixture is 84°F dry bulb and 72°F wet bulb temperature is cooled to 63°F dry bulb and 59°F wet bulb temperature by chilled water cooling coil and delivered as supply air to the theater. Calculate the tons of refrigeration required.Answer: B A. 123 B. 125 C. 124 D. 128 24. A room being air conditioned is being held at 25°C dry bulb and 50% relative humidity. A flow rate of 5 m3/s of supply air at 15°C dry bulb and 80% RH is being delivered to the room
to maintain that steady condition at 100 Kpa. What is the sensible heat absorbed from the room air in KW?Answer: B A. 50.8 B. 60.8 C. 40.5 D. 70.9 25. Copra enters a dryer containing 60% water and 40% solids and leaves with 5% water and 95% solids. Find the weight of water removed based one each pound of original product.Answer: D A. 0.34 lb B. 0.63 lb C. 0.86 lb D. 0.58 lb
26. Copra enters a dryer containing 60% water and 40% solids and leaves with 5% water and 95% solids. Find the weight of water removed based one each pound of final product.Answer: A A. 1.375 lb B. 1.19 lb C. 1.872 lb D. 2.345 lb 27. The temperature of the air in a dryer is maintained constant by the use of steam coils within the dryer. The product enters the dryer at the rate of 1 metric ton per hour. The initial moisture content is 3 kilograms moisture per kilograms dry solid and will be dried to a moisture content of 0.10 kg moisture per kg solid. Air enters the dryer with a humidity ratio of 0.016 kg moisture per kg dry air and leaves with a relative humidity of 100% while the temperature remains constant at 60°C. If the total pressure of air is 101.325 Kpa, determine capacity of forced draft fan to handle this air in m 3/min.Answer: D A. 80 B. 84 C. 82 D. 86 28. Wet material, containing 215% moisture (dry basis) is to be dried at the rate of 1.5 kg/sec in a continuous dryer to give a product containing 5% moisture (wet basis). The drying medium consists of air heated to 373°K and containing water vapor equivalent to a partial pressure of 1.40 Kpa. The air leaves the dryer at 310°CK and 70% saturated. Calculate how much air will be required to remove the moisture.Answer: C A. 213,233 kg/hr B. 177,142 kg/hr C. 177,242 kg/hr D. 198,234 kg/hr 29. A Dryer is to deliver 1000 kg/hr of palay with a final moisture content of 10%. The initial moisture content in the feed is 15% at atmospheric condition with 32°C dry bulb and 21 degrees centigrade wet bulb. The dryer is maintained 45°C while the relative humidity of the
hot humid air from the dryer is 80%. If the steam pressure supplied to the heater is 2 Mpa, determine the heat supplied by heater in kw.Answer: B A. 3.23 B. 5.46 C. 4.23 D. 6.23 30. A Dryer is to deliver 1000 kg/hr of palay with a final moisture content of 10%. The initial moisture content in the feed is 15% at atmospheric condition with 32°C dry bulb and 21 degrees centigrade wet bulb. The dryer is maintained 45°C while the relative humidity of the hot humid air from the dryer is 80%. If the steam pressure supplied to the heater is 2 Mpa, determine the air supplied to dryer in m3/hr.Answer: A A. 1332.25 B. 1532.34 C. 1234.23 D. 1982.34 31. At 30°C, air-vapor mixture has a relative humidity of 70%. Find the humidity ratio if barometric pressure is 100°C. At 30°C, P sat = 4.246 kpaAnswer: D A. 0.123 B. 0.986 C. 0.054 D. 0.019 32. The humidity ratio of air is 0.045. If barometric pressure is 101 kpa, find the partial pressure of water vapor.Answer: C A. 4.23 kpa B. 7.34 kpa C. 6.81 kpa D. 5.23 kpa 33. Air at 36°C and pressure of 101.2 kpa has a density of 1.08 kg/m 3. Find the humidity ratio of air.Answer: A A. 0.0352 B. 0.6350 C. 0.0635 D. 0.0173 34. What is the enthalpy of the air-vapor mixture at 60% RH and 35°C when the barometric pressure is 102 kpa? At 35°C: Psat = 5.628, hg = 2565.3Answer: A A. 89.63 KJ/kg B. 74.23 KJ/kg C. 67.34 KJ/kg D. 53.34 KJ/kg 35. Air-vapor mixture has an enthalpy of 75 KJ/kg at 30°C. Find the partial pressure of water vapor. At 30°C: hg = 2556.3 KJ/kgAnswer: D A. 6.34 kpa B. 1.34 kpa C. 4.231 kpa D. 2.791 kpa
36. Air in an air conditioner enters at 60% RH with w = 0.021 and leaves at 25°C dry bulb and 16°C wet bulb. If mass of air is 10 kg/s, find the refrigeration capacity in tons of refrigeration.Answer: B At 60% RH, 2 = 0.021: h = 87KJ/kg, v = 0.903 m3/kg At 25°C db, 16°C wb: h = 45 KJ/kg; A. 134.34 TR B. 119.45 TR C. 102.45 TR D. 98.34 TR
37. A 160 kw air conditioner has an initial condition of 40°C and 60% RH and leaves at 40°C db and 60% RH: h = 112 KJ/kg, w = 0.93m 3/kg; At 20°C db and 20% RH: h = 26 KJ/kg.Answer: D A. 3.22 m3/s B. 2.62 m3/s C. 2.12 m3/s D. 1.73 m3/s 38. Outside air in an air conditioning unit has a mass of 50 kg at 45°C is mixed with recirculated air at 30 kg at 26°C. Find the temperature after mixing.Answer: D A. 35.23°C B. 43.23°C C. 37.87°C D. 40.40°C 39. Twenty kilograms air enters the dryer at 25°C db and 30% RH. Fifteen kg of recirculated air from the dryer has a partial pressure of water vapor of 10 kpa. Find the humidity ratio after mixing.Answer: A At 25°C db, 30% RH: w = 0.0059 A. 0.0325 B. 0.1930 C. 0.0653 D. 0.0842 40. Sixty kilogram air with enthalpy of 80 KJ/kg is mixed with another x air until the mixture is 100 kg and 70 KJ/kg enthalpy. Find the enthalpy of x air before mixing.Answer: D A. 23.23 KJ/kg B. 17.45 KJ/kg C. 43.75 KJ/kg D. 55.01 KJ/kg 41. An 80% efficient cooling tower has water entering at 48% and wet bulb temperature of air entering at 25°C. Find the water exit temperature of water. Answer: B A. 16.23°C B. 29.60°C C. 32.34°C
D. 23.44°C 42. Water enters the cooling water at 50°C and leaves at 28°C while the heat rejected to air is 100 KW. Find the capacity of the pump needed to pump the water A. 1.08 li/s B. 3.22 li/s C. 2.34 li/s D. 4.23 li/s
43. The evaporative condenser of an ammonia refrigeration plant has a water flow rate of 130 kg/s and enters at natural draft cooling tower at 43°C. The water is cooled to 30°C by air entering at 27°C db 24°C wet bulb. The air leaves the tower as 90% RH and 32°C db. Calculate the percent make-up water needed the tower.Answer: B At 27°C db and 24°C wb: h = 72.5 KJ/kg, w = 0.0178 At 90% RH and 32°C db: h = 102 KJ/kg, w = 0.0275 A. 2.34% B. 1.79% C. 3.12% D. 2.84% 44. A cooling tower cools water from 39°C to 27°C at the rate of 20 kg/s. Air enters he tower at 22°C at the rate of 36 kg/s. Find the temperature of air leaving the tower.Answer: B A. 50.71°C B. 28.86°C C. 45.23°C D. 34.45°C 45. The sensible heat rate is 0.8, which of the following is correct?Answer: A A. 20 latent and 80 sensible heat B. 80 latent heat and 20 sensible heat C. 80 sensible heat and 20 sensible heat and latent heat D. 20 latent heat and 80 sensible and latent heat 46. The amount of 100:Answer: A A. B. C. D.
sensible heating, the sensible heat ratio of 0.80 and a total cooling load of 80 20 100 60
47. A coil has an inlet temperature of 60°F and outlet of 90°F, if the mean temperature of coil is 110°F, find the bypass factor of the coil.Answer: A A. 0.4 B. 2 C. 1 D. 3
48. A 4m x 4m x 4m room has a relative humidity of 80%. The pressure in the room is 120 kpa and temperature is 36°C (Psat = 5.628). What is the mass of vapor in the room (R v= 0.4615 Kpa-m3/kg-°K).Answer: A A. 2.03 B. 1.50 C. 0.80 D. 4.80
49. The evaporative condenser of an ammonia refrigeration plant has a water flowrate of 126 kg per second and enters a natural draft cooling tower at 40°C. The water is cooled to 29°C by air entering at 38°C and 24°C wb. The air leaves the tower as saturated 40°C db. Calculate the make-up water required in kg per hour. Answer: C Water properties: At 40°C, hf = 167.48 KJ/kg At 29°C, hg = 121.43 KJ/kg Air properties: At 38°C db and 24°C wb: h = 72.5 KJ/kg w = 0.013 KJ/kg At 40°C db saturated: h = 166 KJ/kg w = 0.0488 KJ/kg A. 8977 B. 8699 C. 8003 D. 8388 PAST BOARD EXAM PROBLEMS 1. Given: Q1 = 160 li/s, N = 1800 rpm (constant) D1 = 254 mm, D2 = 203.2 mm.Answer: C A. 130 li/s B. 180 li/s C. 128 li/s D. 145 li/s 2. Reversed Carnot operates between -8°C and 18°C. Find the COP.Answer: D A. 4.56 B. 8.34 C. 6.34 D. 10.19 3. 150 grams at 76°C vaporized completely. Find the head added during isothermal process.Answer: A A. 348 KJ B. 643 KJ C. 456 KJ
D. 123 KJ 4. A 120 m3/s of air has a dry bulb temperature of 18°C. What is the standard air volume?Answer: A A. 121.28 m3/s B. 128.34 kg/s C. 124.34 kg/s D. 132.45 kg/s
5. Given CH4 and 15% excess air. Find the mass of air in kg per mass of kg fuel.Answer: C A. 17.16 kg/kg B. 21.23 kg/kg C. 18.73 kg/kg D. 34.23 kg/kg 6. Available enthalpy of turbine is H = 1140.9 KJ/kg, turbine efficiency is 70%, full load capacity is 4,500 Kw. Find the full load steam consumption in kg/Kw-hr.Answer: B A. 2.34 B. 4.51 C. 3.45 D. 7.45 7. 150 grams of water at 75°C is heated at constant pressure. The water is completely vaporized, what is heat added?Answer: D A. 2321.37 KJ B. 4231.34 KJ C. 3214.23 KJ D. 348.21 KJ 8. An engine is required to produce 4,500 kg of dry steam per hour. The quality of steam in it is 90%. What must be the weight of the wet steam?Answer: D A. 477.8 kg/hr B. 528 kg/hr C. 400 kg/hr D. 500 kg/hr 9. The refrigeration system has refrigerating cycle per kilogram of 220 KJ. The heat required to remove is 630 KJ/hr. Calculate the mass circulated per hour.Answer: D A. 3.186 B. 8 kg/hr C. 10 kg/hr D. 2.86 kg/hr 10. The pressure and temperature entering the turbine is 18000 Kpa and 380°C. The temperature leaving the turbine is 20 kpa. The quality of steam is entering the condenser is 90%. What is the turbine work?Answer: A A. 833.33 KJ/kg B. 753 KJ/kg
C. 654.32 KJ/kg D. 945.67 KJ/kg 11. Air in a rigid vessel has an initial temperature of 30°C and a final temperature of 80°C. The work done is:Answer: D A. 3 KJ B. 30 KJ C. 20 KJ D. 0 KJ 12. A fuel is represented with C3H8 burned with 50% excess air. If mass of fuel is 0.07 kg, find the mass of air needed.Answer: C A. 1.23 kg B. 1.638 kg C. 23.4 kg D. 5.34 kg 13. A 30 cm x 40 cm reciprocating pump running at 250 rpm discharges 210 li/s of water. Find the percent slip of the pump.Answer: D A. 4.23% B. 8.34% C. 5.76% D. 10.87% 14. A Rankine cycle has an initial mass of liquid flowing at 10 kg at 76%. If final enthalpy is 379.6 KJ, find the change of enthalpy of the system.Answer: A A. 655.75 KJ B. 834.34 KJ C. 763.45 KJ D. 934.56 KJ 15. A venturi meter has an initial inlet pressure of 500 Kpa and velocity of 2 m/s. The top has a diameter of 18 cm and 8 cm diameter. The top is 6 m high and bottom has 4.5 m high. Find the exit pressure.Answer: D A. 324.45 kpa B. 534.23 kpa C. 452.34 kpa D. 546.46 kpa 16. A venturi meter has a pressure head difference of 8 m. The volume of water flowing is 6900 li/min. The inlet diameter is 20 cm. Find the outlet diameter.Answer: A A. 10.60 cm B. 14.23 cm C. 12.34 cm D. 16.34 17. An Otto cycle has an inlet condition of 101 kpa and 30°C. The compression ratio is 8 maximum temperature of the cycle 1500°C. Find the mean effective pressure of the system.Answer: A A. 578 kpa B. 735 kpa
C. 653 kpa D. 823 kpa 18. An Otto cycle has a compression ratio of 6 and inlet condition of 98 kpa and 15°C. The maximum temperature of the system is 3000°C. Find the maximum pressure of the system.Answer: B A. 4334.32 kpa B. 6682.23 kpa C. 5634.45 kpa D. 7049.53 kpa 19. A turbine has an available enthalpy of 3000 KJ/kg in a Rankine cycle. The pump work has also 20 KJ/kg. For a flow of 2 kg/s, find the system output.Answer: A A. 5960 kw B. 6080 kw C. 643 kw D. 9834.45 kw 20. The initial pressure of the system during isometric process is 100 kpa. If the heat during the process is 10 kw, find the enthalpy change.Answer: C A. 5 kw B. 15 kw C. 10 kw D. 20 kw 21. In a Rankine cycle, the steam turbine inlet has a condition of 3126 KJ/kg enthalpy and entropy of 6.68 KJ/kg-K. The quality after expansion is 80% and enthalpy of 2104.3 KJ/kg with h f = 209.33 KJ/kg. Find the efficiency of the cycle.Answer: B A. 23.45% B. 35.04% C. 30.34% D. 38.44% 22. Find the degree superheat of steam at 0.89 Mpa and 180°C. At 0.89 Mpa: tsat = 174.90°CAnswer: C A. 4.34°C B. 6.44°C C. 5.10°C D. 7.45°C 23. The available enthalpy of steam of the exit of boiler in a Rankine cycle is 3000 KJ.kg and enthalpy at the entrance of turbine in 2950 KJ/kg. If mass of steam is 1 kg/s, find the heat loss between the boiler exit and turbine entrance.Answer: D A. 10 kw B. 30 kw C. 20 kw D. 50 kw 24. Find the pressure at the bottom of an 8 m column of water.Answer: D A. 45.23 kpa B. 65.23 kpa C. 53.45 kpa D. 78.48 kpa
25. Air is flowing through a 20 cm diameter pipe has a velocity of 5 m/s. If temperature of air is 25 °C kpa pressure, find the mass flow of air in the pipe.Answer: C A. 0.11 kg/s B. 0.33 kg/s C. 0.22 kg/s D. 0.44 kg/s 26. An ammonia refrigeration operates between -6°C evaporator temperature and 30°C condensing temperature. Find the quality after expansion.Answer: C At -6°C: hf = 172.371 KJ/kg hg = 1455.00 KJ/kg At 30°C hf = 341.769 KJ/kg hg = 1486.14 KJ/kg A. 11.23% B. 15.34% C. 13.21% D. 16.34% 27. Air with 20°C wb and 30°C had a relative humidity of:Answer: B A. 20% B. 40% C. 30% D. 50% 28. A pump delivers 100 li/s of water at a head of 50 m. Find the water power.Answer: B A. 29 kw B. 49 kw C. 39 kw D. 59 kw 29. A steam turbine has an inlet enthalpy of 2800 KJ/kg with velocity of 40 m/s. The exit steam condition 2650 KJ/kg. Find the exit velocity.Answer: A A. 549.18 m/s B. 323.55 m/s C. 456.34 m/s D. 658.23 m/s 30. Flow of water taking over in a pipe having a velocity of 10 m/s. Determine the velocity head of the water. Answer: B A. 50.1 m B. 5.1 m C. 8.2 m D. 100 m 31. The length of pipe is 168 meters. If the pressure drop is 50 Kpa for every 30 meters, what is the total pressure drop?Answer: C A. 260 kpa B. 300 kpa C. 280 kpa D. 100 kpa
32. After checking on the properties and phase descriptions of the quality is found to be x = 0.70. How many % of the mass is in the liquid phase?Answer: D A. 70% B. 100% C. 0.70% D. 30% 33. The diameter of a pipe at the larger end is 0.5 cm and at the smaller end is 0.2 m. The larger and smaller ends are located 7 meters and 3 meters, respectively from datum line. If at the larger end, the velocity is 1.2 m/s and the pressure is 5200 KN/m 2, compute the pressure at the smaller end.Answer: C A. 6501.84 kpa B. 7815.99 kpa C. 5211.82 kpa D. 4800.92 kpa 34. Convert a vacuum pressure of 110 mm of mercury into absolute pressure if atmospheric pressure is 10.5 of H2O.Answer: B A. 3.7 m of H2O B. 9.1 m of H2O C. 45.6 m of H2O D. 99.5 H2O 35. A tank contains H2O. What is the intensity of pressure at a depth of 6 meters.Answer: C A. 68 kpa B. 78 kpa C. 58.8 kpa D. 48.7 kpa 36. Water is flow through a pipe at 15 li/sec. The inlet diameter of pipe is 12 cm and the exit diameter is 15 cm. If H2O is to be pumped from H 2O source and heat loss is 2 kw, determine the power input to the pump.Answer: A A. 2.2 kw B. 1.2 kw C. 3.2 kw D. 4.2 kw 37. Three tons of fish is to be stored at a temperature of -10°C for 24 hours. The product enters the chiller at a temperature of 8°C. The latent heat above freezing is 0.41 Kcal/kg-C and 0.76 Kcal/kg-C respectively and its latent heat of fusions is 51 kcal/kg. If the freezing temperature of the product is -2.2°C, determine the product load in Kcal/24 hours.Answer: C A. 153,000 B. 158,019 C. 168,566 D. 10,000 38. A boiler has a bursting pressure, Bp of 600 kpa and a factor of safety; FS, of 8 is employed in design. An engineer, would you advice to have a working pressure, WP, of 500 kpa? Answer: C A. No, WP must be higher than 500 kpa
B. Yes, since BP is 600 Pa. C. No, WP is only 75 kpa at a FS of 8 D. Yes, to attain better efficiency
39. The analysis of a product of combustion on dry basis, when C8H18 was burned with atmospheric air, is as follow: CO2 = 12%, CO = 75%, O2 = 3.10%, N2 = 84.24%. Compute the % theoretical used for combustion.Answer: C A. 100% B. 121% C. 112% D. 21% 40. What is the specific humidity of dry air?Answer: D A. 150 B. 50 C. 100 D. 0 41. Water enters the cooling tower at 45°C. The approximate leaving water temperature is 30°C. If the atmospheric condition is 25 degrees C wet bulb, determine the cooling effectiveness of the cooling tower?Answer: B A. 95% B. 75% C. 25% D. 50% 42. The temperature of a solution is 31°C. Convert the equivalent Fahrenheit reading to absolute Fahrenheit temperature.Answer: D A. 560.8°R B. 520.2°R C. 575.5°R D. 547.8°R 43. One kilogram of air is compressed adiabatically and in steady flow. The compression efficiency is 80% and work done is 265 KJ/kg. Compute heat.Answer: B A. 212 KJ/kg B. 0 C. 1 KJ/kg D. 331.25 KJ/kg 44. What is the ton of refrigeration required to cool 15,000 lb of fresh pork from a temperature of 89°F to 32°F in 24 hours? Specific heat above freezing of fresh pork is 0.68 Btu/lb-°F.Answer: C A. 593.78 tons B. 410.6 tons C. 2.02 tons D. 426.12 tons
45. A room is 10 ffet long, 12 feet wide and 8 feet high. The inside and outside temperature are 8°F and 65°F, respectively. Compute the heat transmitted through the walls if the coefficient of heat transmission is 0.12 Btu/square-°F-hr.Answer: B A. 4049.28 Btu/hr B. 2407.78 Btu/hr C. 996.81 Btu/hr D. 1208.84 Btu/hr 46. A refrigerator is maintained at 5°C. Heat is removed from the stored food at a rate of 330 KJ/min. What is the refrigerator’s coefficient of performance if the necessary power input to the refrigerator is 3.5 kw?Answer: C A. 0.45 B. 8.95 kw C. 1.57 kw D. 94.28 kw 47. A building has to be maintained at 18°C at all times. A heat pump is required for this. When temperature outside the building drops to -6°C, the building losses heat at a rate of 12,000 KJ/hr. Compute the least power necessary to drive the heat pump.Answer: D A. 48.15 kw B. 25.06 kw C. 0.16 kw D. 0.275 kw 48. A refrigerating machine that is classified as a one-ton machine has the capacity to produce a cooling effect of:Answer: B A. 500 Kcal/hr B. 3000Kcal/hr C. 300 Kcal/hr D. 50Kcal/hr 49. Using a psychometric chart, what is the wet bulb temperature of air contained in a room at a temperature of 308°K, relative humidity of 40% and a pressure of 1 atmosphere?Answer: A A. 350°K B. 297°K C. 294°K D. 290°K 50. 300 KJ of heat flow by conduction from the outside to the inside cold storage in one hour. If the temperature and all other conditions are the same, what is the heat flowing through the cold storage in two hours? A. 600 KJ B. 300 KJ C. 900 KJ D. 1,200 KJ 51. Boiling temperature of water is:Answer: C A. 273°K B. 32°F C. 100°C D. 212°K
52. A 25 cm x 38 cm, 4-stroke, single acting, running at 600 rpm diesel engine has a brake power of 150. Find the volumetric rate, m3/kw-hr.Answer: C A. 4.23 B. 1.23 C. 2.24 D. 3.45 53. At 1.11°C evaporator temperature the inlet enthalpy is 410.4 KJ/kg and exit enthalpy = 1471.6 KJ/kg. If mass flow rate is 3 kg/min, find the refrigerating effect.Answer: D A. 23 B. 34 C. 45 D. 53 54. When dry bulb and wet bulb temperatures are the same, its relative humidity is:Answer: C A. 0% B. 50% C. 100% D. 75% 55. Bypass factor of coils is 0.7 for one row. What is the bypass factor if there are 10 coils in a row? Answer: B A. 0.029 B. 0.70 C. 700 D. 0.49 56. A heat pump is used to heat a house during the winter. The house is to be maintained at 21°C at all times. The house is estimated to be losing heat at the rate of 35,000 KJ/hr when the outside temperature drops to -5°C. Determine the power required to drive this heat pump unit.Answer: D A. 3.32 kw B. 4.34 kw C. 5.34 kw D. 0.86 kw 57. An engine has a power output of 4.5 hp with 74% efficiency. What will be the KW/hp? Registered to the meter?Answer: A A. 1 B. 2 C. 3 D. 4 58. At 30°C and saturated, Uf = 125.79 KJ/kg. If mass is 2 kg, find the internal energy, KJ?Answer: C A. 125.79 B. 134.56 C. 251.58 D. 345.67
59. A rigid vessel has a temperature of 80°C (v f = 0.0010291 m3/kg). If mass is 10 kg, find the volume of liquid.Answer: B A. 8.34 li B. 10.29 li C. 12.33 li D. 14.33 li 60. A diesel engine is 447 kw at sea level, it will operate at 2700 m elevation with correction factor of 0.71, temperature of 40.1°C correction factor of 0.90. Find the brake power if it will operate at higher elevation.Answer: A A. 285.63 kw B. 342.34 kw C. 387.23 kw D. 452.34 kw 61. A refrigeration system using refrigerant 22 has a compressor of 60 kw. The evaporator entrance = 254.4 KJ/kg, exit = 401.6 KJ/kg. If mass flow of refrigerant is 1.2 kg/s, find the COP of the system.Answer: B A. 2 B. 3 C. 4 D. 5 62. A turbine has a suction pressure of 200 kpa. If head loss is 4 m volume flow is 5 m 3/s, find the water power.Answer: C A. 456.77 kw B. 1196.20 kw C. 803.80 kw D. 1863.45 kw 63. A boiler operates at 82.5% efficiency while the mass of steam generated is 885,000lb in 4 hrs. The enthalpy of steam is 1362 Btu/lb and feed is 249.10 Btu/lb while the fuel used for boiler has a heating value of 13,850 Btu/lb. Find the mass of fuel needed per day in short tons.Answer: D A. 10.78 B. 8.34 C. 3.45 D. 258.59 64. In a 150 m pipe, for every 20 m length there’s a head loss of 40 kpa. What is the total head loss? Answer: A A. 300 kpa B. 200 kpa C. 150 kpa D. 400 kpa 65. A 20 cm x 35 cm diesel engine with 4 cylinders and operating on a four stroke, has a rated power of 160 kw and is running at 250 rpm. Find the volume displacement per brake power developed.Answer: D A. 0.9 m3/min-kw B. 0.06 m3/min-kw C. 0.1 m3/min-kw
D. 0.0344 m3/min-kw 66. What is the BTU equivalent for 1 horsepower?Answer: B A. 778 B. 2545 C. 746 D. 3.41 67. A high temperature source at 950°K provides 580 KJ heat to a heat engine. The heat engine converts 200 KJ net work and rejects the balance to a temperature sink at 298°K. Compare the thermal efficiency Et of this engine to the thermal efficiency E rev of the Carnot cycle reversible heat engine.Answer: B A. Et = Erev B. Et< Erev C. Erev< Et D. None of these 68. A refrigerator plant stored 8 metric tons of eggs at a temperature of 15°C. To preserve the eggs by not spoiling them, they have to be cooled at -8°C. What is the refrigerating capacity of the plant in tons if it is cooled in 12 hours? The specific heat of the eggs above the below freezing is 0.95 Kcal/kg-°C and 0.4 Kcal/kg-°C respectively. The latent heat of fusion is 68.50 Kcal/kg. The freezing temperature is -3°C.Answer: B A. 12.5 tons of ref B. 19.3 tons of ref C. 23.1 tons of ref D. 34.2 tons of ref 69. A refrigerator plant stored 8 metric tons of eggs at a temperature of 15°C. To preserve the eggs by not spoiling them, they have to be cooled at -8°C. What is the refrigerating capacity in Kcal? The specific heat of the eggs above the below freezing is 0.95 Kcal/kg-°C and 0.4 Kcal/kg-°C respectively. The latent heat of fusion is 68.50 Kcal/kg. The freezing temperature is -3°C.Answer: B A. 180,000.6 B. 700,800 C. 14,000.2 D. 142,000 70. A 90 kg air at 20°C is mixed with 45 kg air at 45°C. Find the temperature after mixing.Answer: C A. 23.34°C B. 26.34°C C. 28.33°C D. 32.34°C 71. Air is compressed isothermally at 20°C from 95 kpa to 750 kpa. Find the work done during the process.Answer: A A. 173.75 KJ/kg B. 187.45 KJ/kg C. 123.44 KJ/kg D. 109.34 KJ/kg
72. Rigid container contains 20 grams of saturated vapor h f = hfg = hg = 2729 KJ/kg. Heater passes 0.3 A and 120 volts in 8 min, find the final enthalpy of steam assuming that Q loss = 4 KJ.Answer: C A. 2890 KJ/kg B. 2065 KJ/kg C. 3393 KJ/kg D. 3084 KJ/kg 73. A Rankine cycle has a turbine work of 590 KJ/kg and efficiency of 90%, pump work is 2.5 KJ/kg and efficiency of 76%. If cycle efficiency is 28%, find the heat added to the cycle. Answer: D A. 2577.60 KJ/kg B. 2345.19 KJ/kg C. 2685.67 KJ/kg D. 1852.40 KJ/kg 74. A 200 mm x 300 mm single stage air compressor running at 450 rpm has a clearance of 2% of the stroke and pressure ratio of 8. What is the volumetric flow?Answer: A A. 237 m3/hr B. 123 m3/hr C. 198 m3/hr D. 383 m3/hr 75. 1 Bo. Hp boils 34.5 lb of steam at 212°F in 24 hours. If you have a 600 Bo. Hp, find the pound of steam.Answer: B A. 12,344 lbs B. 20,700 lbs C. 16,390 lbs D. 25,300 lbs 76. In piping system a bare pipe has a heat loss of 6 kw/m. By insulating the pipe, the heat loss will reduce to 0.90 kw/m. If total length of pipe is 40 m and operation per month is 600 hrs, how much energy saved per month because of insulation?Answer: B A. 2.345 x 108 KJ B. 1.102 x 106 KJ C. 4.41 x 108 KJ D. 1.453 x 106 KJ 77. A fluid at 120 kpa and has 25°C temperature has a velocity of 180 m/s. Find the stagnation pressure.Answer: C A. 125.54 kpa B. 243.45 kpa C. 144.34 kpa D. 110.23 kpa 78. In a Rankine cycle the quality of steam leaving the turbine is 90% with mass flow of 4800 kg/hr wet steam. Find the mass of vapor.Answer: D A. 1295 kg/hr B. 2841 kg/hr C. 3089 kg/hr D. 4320 kg/hr
79. A turbine has an efficiency of 75% and a kilowatt output of 5500 kw at full load. If the available energy of the turbine is 1200 KJ/kg, determine the steam flow at the turbine per hour.Answer: B A. 900 kg/hr B. 22,000 kg/hr C. 7,333.33 kg/hr D. 6.11 kg/hr 80. In an air compressor, the compression takes place at a constant internal energy and 50 KJ of heat are rejected to the cooling water every kg air. Find the work required for compression.Answer: B A. 5 KJ/kg B. 50 KJ/kg C. 15 KJ/kg D. 30 KJ/kg 81. A certain location has barometric reading of 720 mm Hg and the gravitational acceleration is 9.2 m/s2. If the temperature of mercury is 9°C at which density is 12,850 kg/m 3, compute the atmospheric pressure.Answer: D A. 94.62 kpa B. 830 kpa C. 58.51 kpa D. 85.12 kpa 82. One Kmol of C8H18 is burned with 100% air containing 25 Kmol of O2. Determine the air-fuel ratio for this combustion process.Answer: A A. 30.38 kg air/kg fuel B. 25.73 kg air/kg fuel C. 35.72 kg air/kg fuel D. 45.07 kg air/kg fuel 83. In a certain steam plant, the turbine develops 1000 Kw. The heat supplied to the steam boiler is 2800 KJ/kg, the heat rejected by the system to the cooling water in the condenser is 2100 KJ/kg and the feed pump work is 5 kw. Calculate the steam flow round the cycle in kg/s.Answer: A A. 1.42 B. 1.24 C. 4.21 D. 2.41 84. The heat transferred to the engine from a furnace is at a rate of 60 MW, compute the thermal efficiency of the heat when the rate of waste heat rejection from a nearby reservoir is 40 MW.Answer: C A. 66.67% B. 50.0% C. 33.33% D. 100% 85. A steam turbine receives a steam flow of 1.35 kg/s and delivers 500 KW. The heat loss in the casing is negligible. Find the heat drop across the turbine, the entrance velocity is 60 m/s. the exit velocity is 36 m/s and the inlet pipe is 3 m above the exhaust pipe.Answer: A A. 372 KJ/kg B. 307 KJ/kg C. 703 KJ/kg
D. 320 KJ/kg
86. A nozzle which is well insulated has a fluid enthalpy of 3025 KJ/kg and a velocity of 60 m/s at the inlet. The fluid leaves the nozzle with an enthalpy of 2790 KJ/kg. Determine the fluid rate of flow in kg/s if the inlet area is 0.10 m2 and specific volume at inlet is 0.19 m 3/kg.Answer: C A. 6.13 B. 3.16 C. 31.6 D. 63.1 87. What is the volume of a rigid tank that contains 15 kilograms of water at a temperature of 95°C (P = 84.55 kpa, vf= 0,001040 m3/kg, vg = 1.982 m3/kg), if 10 kilograms of this water liquid and the remaining is in vapor form?Answer: B A. 12.892 cubic meters B. 9.9204 cubic meters C. 0.0156 cubic meters D. 5.6549 cubic meters 88. A single acting reciprocating pump with a diameter of 0.18 m and a stroke of 0.30 m, delivers water at a rate of 0.18 cubic meter per minute. What is the percentage slip it delivers at 25 revolutions per minute?Answer: A A. 5.7% B. 8.4% C. 10.5% D. 1.6% 89. At P2.50 per kw-hr, how much will it cost to maintain a temperature of 96 degrees F for 24 hour in a box 2 ft square on each side if the outside temperature is 72 degrees F and the overall heat transfer coefficient for the box is 0.1 Btu/hr-sq-ft degree difference in temperature?Answer: A A. P1.01 B. P2.50 C. P1.50 D. P2.01 90. An air bubbles rises from the bottom of a water storage tank. The temperature at the surface of the bottom of the tank is 77 degree F rises to the surface where the temperature is 83 degree F. what is the percent increase in volume of the bubble if the height of water in the tank is 20 feet? The atmospheric pressure is 14.7 psia. If the height of the water in the tank is 20 feet? The atmospheric pressure is 14.7 psia.Answer: C A. 80% B. 75% C. 61% D. 52% 91. If the available water power of a hydrostatic station is 3,500 MW and head of water is 280 m, determine the water rate of low.Answer: D A. 1420 cubic meters B. 12,500 cubic meters
C. 875 cubic meters D. 1275.10 cubic meters 92. Determine the heat transfer to the cooling fluid in a condenser operating under steady flow condition with steam entering with an enthalpy of 2300 KJ/kg and a velocity of 350 m/s. The condensate leaves with an enthalpy of 160 KJ/kg and a velocity of 70 m/s.Answer: D A. -1992 KJ/kg B. -2910 KJ/kg C. 2910 KJ/kg D. -2199 KJ/kg 93. A single acting reciprocating pump has a diameter of 0.12 meter and a stroke of 0.25 meter. Compute the theoretical discharge if the pump delivers water at 60 rpm.Answer: C A. 0.5965 cubic meter/min B. 0.05965 cubic meter/min C. 0.1698 cubic meter/min D. 0.01698 cubic meter/min 94. A gas turbine unit has a pressure ratio of 6/1 and a maximum cycle temperature of 600°C. The isentropic efficiencies of the compressor and turbine are 0.82 and 0.85 respectively. Calculate the power output in KW of an electric generator geared to the turbine when air enters the compressor at 15°C and a rate of 15 kg/s. For the compression process c p = 1.0005 KJ/kg-K and k = 1.4, for the expansion process cp = 1.11 KJ/kg-K and k = 1.333.Answer: D A. 902 KW B. 920 KW C. 209 KW D. 935 KW 95. A diesel generating unit with a generator efficiency of 85% has an output of 900 kw-hr. If the mass of fuel is 200 kg, compute the fuel rate of the engine.Answer: B A. 0.80 kg/kw-hr B. 0.19 kg/kw-hr C. 0.40 kg/kw-hr D. 0.95 kg/kw-hr
96. A water-tube condenser has a total of 60 tubes. If these two are passes, then compute the number of tube per pass.Answer: B A. 60 B. 30 C. 15 D. 2 97. A tank contains saturated vapor of 35 kilogram at a temperature of 90 degrees C (h g = 2660.15 KJ/kg). Compute enthalpy.Answer: B A. 61920 B. 93105 C. 82677
D. 47632 98. A steam ower plant operates on a simple ideal Rankine cycle. The steam enters the turbine at 3 Mpa and 350°C ( h = 3115.3 KJ/kg, s = 6.7428 KJ/kg-K) and is condensed at a pressure of 75 kpa (tsat = 91.78°C). What is the back work ratio of the plant?Answer: C Steam data: 75 kpa: sf = 1.213; sfg =6.2434 vf = 1.037 li/kg hf = 384.39; hfg = 2278.6 A. 0.8% B. 0.6% C. 0.43% D. 0.1% 99. What is the power produced by a steam power plant which has a pump work of 5 KJ/kg and a turbine work of 550 KJ/kg? The mass flow rate is 15 kg/sec?Answer: D A. 7250 KW B. 9000 KW C. 9500 KW D. 8175 KW 100. A prony brake test was done for an electric motor. The motors turn 1,800 revolutions per minute with a torque of 3 Newton-meter. Calculate the motor power output in watts.Answer: B A. 166.66 watts B. 565.44 watts C. 5,400 watts D. 600 watts 101.
What is the specific gravity of an oil which has a Baume reading of 28?Answer: B A. 0.215 B. 0.886 C. 0.562 D. 0.774
102. Heat flows inside a cold storage by conduction. The amount of heat flowing is 250 KJ in one hour. Compute the amount of heat flowing to the storage in 3 hours, assuming all conditions are the same.Answer: C A. 83.3 KJ B. 250 KJ C. 750 KJ D. 500 KJ
103. An electric motor draws a current of 25 amperes from a power source of 120 volts. Compute the power used.Answer: B A. 6 kw B. 2 kw C. 4.8 kw D. 0.21 kw
104. An ideal gas at 50 psig and 110°F is heated in a closed cylindrical vessel. What is the temperature if the pressure gauge reading is 100 psig?Answer: B A. 700 degree F B. 550.5 degree F C. 532.76 degree F D. 700 degree F 105. The compression ratio of an ideal Otto cycle is 6. Under the cold air assumption, compute the thermal efficiency of the cycle.Answer: B A. 48.84% B. 51.16% C. 58.29% D. 60.40% 106. The primary winding of a transformer is connected to a 240 V power source. What is the secondary voltage if the transformer has a rated ratio of 1 to 2?Answer: B A. 240 B. 480 C. 12100 D. 400 107.
One foot of H2O is equal to Answer: A A. 62.4 psf B. 43 psf C. 79.3 psf D. 84.5 psf
108.
The relation between the °R scale and °K scale isAnswer: A A. R = 1.8 K B. R = 0.55 K C. R = 32 K D. R = 6 K
109. A vapor compression engine operates between temperatures -10°F and -190°F. Find the coefficient of performance.Answer: D A. 4.5 B. 3.5 C. 6 D. 2.5 110. An Otto cycle has an initial temperature of 30°C and pressure of 100 kpa. The maximum temperature of the cycle is 1500°C with compression ratio of 6. Find the maximum pressure of the cycle.Answer: D A. 567 kpa B. 2938 kpa C. 3304 kpa D. 3511 kpa
111. In an R-12 refrigeration system, the mass flow of refrigerant is 3.5 kg/s and refrigerating effect of 250 KJ/kg. If COP is 5, gind the heat rejected.Answer: C A. 1000 kw B. 1025 kw C. 1050 kw D. 1200 kw 112What is the efficiency of the pump having a head of 500 m and mass of water of 50 kg/s if motor driving has a power of 300 kw.Answer: C A. 73.45% B. 78.49% C. 81.75% D. 87.35% 112. B
The pressure of water is 30 kpa. What is the absolute pressure in meter of water?Answer: A. B. C. D.
10.23 m of H2O 13.38 m of H2O 15.34 m H2O 17.34 m of H2O
113. A gas turbine has a turbine work of 1000 KJ/kg and compressor work of 500 KJ/kg. If the mass of circulating is 2 kg/s, find the net work output of the turbine?Answer: C A. 500 kw B. 750 kw C. 1000 kw D. 1250 kw
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