40568

CHE CALCULATIONS For numbers 1 to 2:  A mixture of ethyl acetate vapor and air has a relative saturation of 50% at 30 0C and a total pressure of 100 kPa. If the vapor pressure of ethyl acetate at 30 0C is 16 kPa [150 and 151 Objective Type Questions] 1. The percentage of air is a. 88%

c. 76%

b. 92%

d. 50%

2. The molal saturation is a. 23%

c. 38%

b. 46%

d. 10%

3. Solid calcium fluoride reacts with sulfuric acid to form calcium and gaseous hydrofluoric acid. The HF is then dissolved in water to form hydrofluoric acid. The source of calcium fluoride is fluorite ore containing 96.0% wt CaF 2 and 4.0% SiO 2. In a typical process, fluorite ore is reacted with 93% wt a queous sulfuric acid, supplied wiwth15% excess of the stoichiometric amount. Ninety five percent of the ore dissolves in the acid. Some of the HF formed reacts with the dissolved silica according to the reaction: 6 HF + SiO 2 → H2SiF6 (aq) + 2 H2O (l) The hydrogen fluoride exiting from the reactor is subsequently dissolved in enough water to produce 60% wt HF. Calculate the quantity of ore needed to produce one metric ton of the acid. a. 1533 kg

c. 1633 kg

b. 1733 kg

d. 1833 kg

4. Oil is extracted from seeds by leaching with organic solvents. Soybean seeds containing 20% oil, 65% inert solids and 15% water are leached with hexane and after extraction the solid residue is removed from the solution of oil in hexane. The residue analyzed 1.0% oil, 88% inert cak e and 11% water. What percent of oil is recovered? a. 90%

c. 96%

b. 82%

d. 87%

5. Process in which the solute components of a gas mixture are dissolved in a liquid. a. evaporation

c. distillation

b. gas absorption

d. drying

For numbers 7 to 9: 100 moles of natural gas containing 80% methane, 15% ethane, and 5% propane is burnt with excess air. 90% of the carbon in the feed is converted to CO 2, and the remaining 10% is converted to CO. 6. If 332.5 moles of oxygen was supplied during the combustion process, what is the percent excess air used? a. 25% b. 35%

c. 30% d. 40%

7. What is the percentage of oxygen in the Orsat analysis of the flue gas? a. 6.03%

c. 7.62%

b. 6.85%

d. 8.43%

8. How many moles of water vapor are formed in the product gas? a. 158 moles

c. 225 moles

b. 185 moles

d. 252 moles

9. It is defined as a fraction of the feed to a process unit that is diverted around the unit and combined with the output stream: a. by pass

c. purge

b. recycle

d. make up

10. Stefan –Boltzmann law states that the emissive power is proportional to the fourth power of absolute temperature. Stated mathematically, Eb = sT 4 where Eb is the emissive power in Btu/(ft 2 h), sis the Stefan-Boltzmann constant, and T is the temperature in R. What is the value of s in W/(m 2-K4), if its value in fps units is 0.171 x10 –8 Btu/(ft 2-h-R4)? a. 4.33 x10 –8

c. 5.66 x10 –8

b. 1.77 x10 –8

d. 8.88 x10 –8

11.  At a specified temperature the molal humidity at saturation a. Depends on pressure but is independent of the properties of the gas b. Independent of pressure and properties of the gas c. Depends on the properties of the gas but is independent of the pressure d. Depends on properties of the gas and the total pressure. 12.  A paint mixture containing 25 wt% of a pigment and the balance water sells for $18/kg, and a mixture containing 12 wt% pigment sells for $10/kg. If a paint retailer produces a blend c ontaining 17 wt% pigment, for how much ($/kg) should it be sold to yield a 10% profit? a. $14.39/kg

c. $12.65/kg

b. $15.04/kg

d. $11.20/kg

13. One hundred pounds of solution containing 80 wt% Na 2SO4 must be obtained by evaporating a dilute solution using a double effect evaporator. If the evaporator from the 2nd effect is 60% of that coming from the first effect and the concentrate of the first effect contains 1 lb Na 2SO4 per pound of water. Calculate for the composition of the feed. a. 31% H2O, 69% Na 2SO4

c. 45% H2O, 55% Na2SO4

b. 45% H2O, 55% Na 2SO4

d. 69% H2O, 31% Na 2SO4

14. Which of the following is true regarding material balance involving combustion? a. This reaction only generates product gases such as H2O, CO2, CO and SO 2. b. This reaction is accompanied with the release of energy only. c. This reaction not only generates product gas such as H 2O, CO2, CO, and SO 2 but also accompanied with the release of energy. d. This reaction can neither generate product gases such as H 2O, CO2, CO, and SO 2 or accompanied with the release of energy. 15. What part of 90% alcohol must be removed and replaced by an equal amount of pure alcohol to make a 95% alcohol solution? a. 5% or less

c. between 5% and 10%

b. 5%

d. 50%

16. Thermal conductivity of material A is 40 W/m-K, that of material B is 40 kcal/m-h- 0C and that of material C is 40 BTU/ft-hr- 0F. Which material is a better conductor of heat in comparison with others? a. material A

c. material C

b. material B

d. both materials A and B

17. Phase diagrams for H2O and CO2 are shown below:

Which of the following is true? a. The top phase diagram is associated with H2O and the bottom phase diagram is associated with CO 2. b. The bottom phase diagram is assoc iated with H2O and the top phase diagram is associated with CO 2. c. both a and b d. none of these For numbers 18 to 19: Fresh orange juice contains 12.0 wt% solids and the balance water, and the concentrated orange juice contains 42.0 wt% solids. Initially a single evaporation process was used for the concentration, but volatile constituents of the juice escaped with the water, leaving the concentrate with a flat taste. The current process overcomes this problem by bypassing the evaporator with a fraction of the fresh juice. The juice is concentrated to 58 wt% solids, and the evaporator product stream is mixed with the bypassed fresh  juice to achieve the desired final concentration. Calculate the following: 18. The amount of product (42% concentrate) produced per 100 kg fresh juice fed to the process. a. 35.3

c. 40.5

b. 28.6

d. 19.2

19. The fraction of the feed that bypass es the evaporator. a. 0.032

c. 0.095

b. 0.150

d. 0.125

20. The simplest form of a mass balance is for systems wherein there is no: a. accumulation, generation and output

c. accumulation, consumption and output

b. generation, consumption and output

d. accumulation, generation and consumption

21. Complete combustion does not produce which product gas? a. carbon dioxide

c. carbon monoxide

b. sulfur dioxide

d. nitrogen monoxide

For numbers 22 to 23:  An evaporator is fed continuously with 50000 kg/h of a solution containing 10% NaOH, 10% NaCl , and the rest water by weight. During evaporation, water is removed as vapor and salt NaCl precipitates as crystals and is removed by filtration. The concentrated liquor leaving the evaporator contains 50% NaOH, 2% NaCl, and the rest water. Determine 22. The mass of water evaporated per hour a. 35200 kg/h

c. 12700 kg/h

b. 8700 kg.h

d. 26040 kg/h

23. The mass of salt precipitated per hour a. 6400 kg/h

c. 5100 kg/h

b. 4800 kg/h

d. 7300 kg/h

24. The mass of concentrated liquor produced per hour a. 2000 kg/h

c. 10000 kg/h

b. 4000 kg/h

d. 30000 kg/h

25. Which of the following is the dimensional formula for the volumetric quantity of water flowing in unit time? a. M t

c. M3 t-

b. L3 t

d. L3 t-

26. The minimum number of phases existing in a system is a. 0

c. 1

b. 2

d. 3

For numbers 27 to 28: Titanium dioxide (TiO 2) is used extensively as a white pigment. It is produced from an ore that contains ilmenite (FeTiO 3) and ferric oxide (Fe2O3). The ore is digested with an aqueous s ulfuric acid solution to produce an aqueous solution of titanyl sulfate [(TiO)SO4] and ferrous sulfate (FeSO 4). Water is added to hydrolyze the titanyl sulfate to H 2TiO3, which precipitates, and H 2SO4. The precipitate is then roasted, driving off water and leaving a residue of pure titanium dioxide. Suppose an ore containing 24.3% Ti by mass is digested with 80% H2SO4 solution, supplied in 50% excess of the amount needed to convert all the ilmenite to titanyl sulfate and all the ferric oxide to ferric sulfate [Fe 2(SO4)3]. Further, suppose that 89% of the ilmenite actually decomposes. Calculate the masses (kg) of ore and 80% sulfuric acid solution that must be fed to produce 1000 kg of pure TiO 2. 27. kg of ore a. 1806 kg

c. 2772 kg

b. 3198 kg

d. 5671 kg

28. kg 80% sulfuric acid solution a. 7380 kg

c. 6920 kg

b. 5510 kg

d. 8250 kg

29. The conversion of a reactant in a process with recycle based on the fresh feed of the reactant and the net product a. once through fraction conversion

c. single pass conversion

b. overall fraction conversion

d. sequential modular conversion

30. If the change in temperature is 180 R, what is the change in 0C? a. 100 0C

c. 212 0C

b. 180 0C

d. 273 0C

31. Percentage humidity is __ the relative humidity. a. always smaller than

c. always greater than

b. not related to

d. none of these

32. For using brackish water for irrigation, it is to be desalinated by evaporation. A fraction of the feed water s sent through an evaporator and the other part is bypassed. The fraction bypassed and the pure water leaving the evaporator are mixed together to give the desalinated water of the desired quality. If the feed water has 500 ppm of s alt, and salt content in the water used for irrigation is to be limited to a maximum of 50 ppm, determine the fraction of the feed water bypassed . a. 0.1

c. 0.3

b. 0.2

d. 0.4

33. It is used in the industry to achieve a liquid-solid separation where solids are formed by a change in temperature. a. crystallizer

c. filter

b. reactor

d. humidifier

34. Which of the following statement is true regarding gauge pressures? a. Gauge pressure is positive for pressure below atmospheric pressure. b. Gauge pressure is positive for pressure above atmospheric press ure. c. Gauge pressure is negative for pressure above atmospheric pressure. d. Gauge pressure is the total pressure relative to atmospheric pressure. 35.  An average person should have no more than 60 grams of fat in his or her daily diet. A certain package of chocolate chip cookies is labeled 1 portion is 3 cookies and also fat: 6 grams per portion. How many cookies may one eat before exceeding 50% of one’s

recommended fat intake? a. 10

c. 15

b. 2

d. 18

36. It is a method of separating chemical substances based on differences in their volatilities: a. absorption

c. distillation

b. drying

d. evaporation

37. Only one of the following statements is correct regarding g c, the Newton’s law conversion factor. Spot the correct statement. a. It is a dimensionless constant. b. It is numerically equal to g, the local acceleration due to gravity. c. Weight of a body is equal to the product of mass and g c. d. Numerical values of gc are different for different system of units. 38.  Ammonia is recovered from a gas mixture containing 25% (volume) CO2 and 75% (volume) NH3 by scrubbing with water. Assuming that CO2 is insoluble in water, determine the percent of ammonia in the entering gas that is absorbed if the gas leaving the sc rubber analyzes 35% NH3. a. 68%

c. 53%

b. 82%

d. 77%

39. The fraction of the feed or some key material in the feed that is converted into products a. conversion

c. yield

b. degree of completion

d. all of these

40. The volume of a microbial culture is observed to increase according to the relation equivalent expression where V is in inch 3 and t is in hours. a. V = 16.39 e 3600 t

c. V = 0.061 e0.003 t

b. V = 16.39 e 0.003 t

d. V = 0.061 e3600 t

V

(cm3) = et, where t is in seconds. Find the

For numbers 41 to 42:  An aqueous solution of ethanol containing 10% by weight ethanol is continuously distilled at a rate of 1000 kg/h in a distillation column. Ten percent of the feed is recovered as distillate product which contains 60% ethanol and 40% water. Calculate the following: 41. The weight of alcohol lost in the bottom product a. 40 kg

c. 80 kg

b. 60 kg

d. 20 kg

42. The composition of ethanol in the bottom product a. 1.11%

c. 3.33%

b. 4.44%

d. 5.55%

43. The dependence of thermal conductivity of a material on temperature is given by an empirical equation k = a e b/T where a and b are constants, and k is in W/m K and T is in K. Spot the true statement from the following set. a. a and b have the same dimension as k. b. a has the dimension of k and b is dimensionless. c. a and b are dimensionless. d. a has the dimension of k and b has the dimension of T. 44. Small animals like rats can live at reduced pressure down to 20 kPa absolute. In a test, a mercury manometer attached to a tank with a mouse inside, reads -64.5 cm Hg and the barometer reads 100 KPa. Will the mice survive? a. Yes, the absolute pressure is 185 kPa b. No, the absolute pressure is 14 KPa c. Yes, the absolute pressure is 86 KPa d. Incomplete data 45. In flue gas analysis by Orsat’s apparatus, carbon dioxide is absorbed by a. potassium hydroxide

c. dilute potassium carbonate

b. cuprous chloride

d. alkaline pyrogallol solution

 Atomic Masses: Ba

137.33

Cl

35.45

N

14

S

32

C

12

Si

28.09

F

19

Ti

47.87

Fe

56

O

16

Ca

40

Na

23

CHE THERMODYNAMICS 46. The number of degrees of freedom for a mixture of ice and water (liquid) are: a. one

c. two

b. three

d. four

47. For liquid water the isothermal compressibility is given by: Κ=

c V (P + b)

where c and b are functions of temperature only. If 1 kg of water is compressed isothermally and reversibly from 1 to 500 bar at 600C, how much work is required? At 600C, b=2,700 bar and c=0.125 cm 3/g. a. 516 J

c. 289 J

b. 403 J

d. 772 J

For numbers 48 to 49: Reported values for the virial coefficients of isopropanol vapor at 200 0C are B = 0 338 cm 3 / mol

C = - 26 000 cm3 / mol

Calculate Z and V for isopropanol vapor at 200 0C and 10 bar by: 48. Ideal gas a. 1, 3934 cm 3/mol

c. 1, 3488 cm3/mol

b. 1, 3539 cm 3/mol

d. 1, 3495 cm3/mol

49. Virial equation of state a. 0.91, 3934 cm3/mol

c. 0.89, 3488 cm3/mol

b. 0.95, 3539 cm3/mol

d. 0.80, 3495 cm3/mol

50. Calorie is equal to 1000 calories (thermochemical calories). How many 8-inch high steps must a 180-lb man climb to expend 400 cal from the piece of cake? a. 100 steps

c. 1000 steps

b. 10000 steps

d. 100000 steps

51. During adiabatic expansion of an ideal gas, work is done by the system and internal energy a. increases

c. decreases

b. remains constant

d. any of these

For numbers 52 to 55:  A gas is confined in a 0.47 m diameter cylinder by a piston, on which rests a weight. The mass of the piston and weight together is 150 kg. The local gravity acceleration is 9.813 m/s 2, the atmospheric pressure is 101.57 kPa. 52. What is the force in Newtons exerted on the gas by the atmosphere, the piston and the weight, assuming no friction between the piston and cylinder? a. 1.91 x104 N

c. 2.03 x104 N

b. 1.56 x104 N

d. 2.28 x104 N

53. What is the pressure of the gas in kPa? a. 105 kPa

c. 110 kPa

b. 128 kPa

d. 117 kPa

54. If the gas in the cylinder is heated, it expands, pushing the piston and the weight upward. If the piston and weight are raised 0.83 m, what is the work done by the gas in kJ? a. -16 kJ

c. -11 kJ

b. 16 kJ

d. 11 kJ

55. What is the change in potential energy of the piston and weight? a. 1.8 kJ

c. 1.9 kJ

b. 1.5 kJ

d. 1.2 kJ

56. When does a vapor become superheated? a. when the temperature of vapor is less than the saturation temperature at given pressure b. when the temperature of vapor is more than the saturation temperature at given pressure c. when the temperature of vapor is equal to the saturation temperature at given pressure d. none of these For numbers 57 to 58: Ice cube initially at -5 0C weighs 20 g and dropped into an insulated vessel containing 100 g of water at 90 0C. 57. What is the final temperature of the water after the ice melted and a temperature has been reached? a. 61.30C

c. 73.40C

b. 69.70C

d. 78.20C

58. What is the entropy change (J/K) accompanying this process? a. 7.7

c. 20.4

b. 16.2

d. 31.8

59. The equation Cp – Cv = -T ( ∂P/∂V) (∂V/∂T)2 can also be expressed as a. Cp – Cv = TV κ 2 / β

c. Cp – Cv = TV β 2 / κ

b. Cp – Cv = TV κ / β

d. Cp – Cv = TV β / κ

60. For an ideal gas the slope of the pressure-volume curve, at a given point will be, a. Steeper for an isothermal than for an adiabatic process. b. Steeper for an adiabatic than for an isothermal process. c. Identical for both the processes. d. of opposite signs. For numbers 61 to 64: Calculate the work (J) done by a sample of 0.10 mol Ne gas that expands isothermally from 0.6 L to 1.2 L at 0 oC according to the following conditions: 61. against a constant external pressure of 0.9 atm. a. 7

c. 151

b. 55

d. 157

62. against a variable pressure which varies with volume according to the expression PV n = k, and with the given data: P x103 (atm) V (L)

194 0.60

134 0.80

a. 7

c. 151

b. 55

d. 157

100 1.00

79 1.20

63. reversibly assuming gas is ideal a. 7

c. 151

b. 55

d. 157

64. reversibly assuming gas obeys van der Waals equation of state (a=0.86 Pa-m6-mol-2and b = 3.18 x10 -5 m3-mol-) a. 7

c. 151

b. 55

d. 157

65. The amount of heat absorbed when CO 2 gas reacts with a solid CaO to form solid CaCO 3 is measured in a bomb calorimeter at constant volume. The data obtained give a direct measure of a. △U

c. △H

b. V△P

d. Cp

For number 66 to 67:  A gas at 1000F has a specific heat at constant pressure of 0.28 BTU/lb- 0F. For every degree rise in temperature the Cp increases by 0.0005 BTU. 66. Calculate the change in enthalpy if the temperature rises by 200 0F. a. 55 BTU/lb

c. 44 BTU/lb

b. 33 BTU/lb

d. 66 BTU/lb

67. Calculate ΔPV in BTU/lb if Cv is less by 0.08 BTU/lb- 0F. a. 16 BTU/lb

c. 24 BTU/lb

b. 10 BTU/lb

d. 19 BTU/lb

68.  A solid is transformed into vapor without going through the liquid phase at a. triple point

c. boiling point

b. below triple point

d. always

For numbers 69 to 70:  A medical ampule containing dextrose (liquid water) at 1000 psia, 1000F and having a volume of 0.3 in 3 is placed in a cylinder having a volume of 1 ft 3. A vacuum is created in the cylinder and the capsule is broken. Dextrose now evaporates and fills the cylinder.  At 1000 psia and 1000F: V = 0.0161 ft 3/lb

H = 70.61 BTU/lb

 At 1000F, Vv = 349.87 ft3/lb

Vl = 0.0161 ft3/lb

Hv =1101.40 BTU/lb

Hl = 68.03 BTU/lb

69. Calculate the final quality of the water-v apor mixture in the cylinder if it reaches a final equilibrium temperature of 100 0F. a. 0.54

c. 0.19

b. 0.38

d. 0.26

70. Calculate the heat transfer with the surroundings. a. 2.8 BTU

c. 3.5 BTU

b. 1.1 BTU

d. 0.9 BTU

71. Equation of continuity comes from a. conservation of energy

c. conservation of work

b. conservation of mass

d. conservation of heat

72.  A closed system is cooled reversely from 1000C to 500C. If no work is done on the system. a. Its internal energy (U) decreases and its entropy (S) increases b. U and S both decrease c. U decreases but S is constant d. U is constant but S decreases 73.  A process consists of two steps: (1) One mole of air at T = 800 K and P = 4 bar is cooled at constant volume to T = 350 K. (2) The air is then heated at constant pressure until its temperature reaches 800 K. If this two-step process is replaced by a single isothermal expansion of air from 800 K and 4 bar to some final pressure P, what is the value of P that makes the work of the two processes the same? Assume mechanical reversibility and treat air as an ideal gas with Cp = (7/2)R and Cv = (5/2)R. a. 2.28 bar

c. 2.52 bar

b. 3.01 bar

d. 1.86 bar

74. What happens in a reversible adiabatic compression? a. heating occurs

c. pressure is constant

b. cooling occurs

d. temperature is constant

For numbers 75 to 76:  A reversible compression of 1 mol of an ideal gas in piston/cylinder device results in a pressure increase from 1 bar to P2 and a temperature increase from 400 K to 950 K. the path followed by the gas during compression is given by PV 1.55 = k, and the molar heat capacity is given by: Cp/R= 3.85 + 0.57x10-3 T [T=K]. 75. Determine the heat transferred during the process. a. 5092 J

c. 6478 J

b. 3355 J

d. 7216 J

76. Calculate the final temperature? a. 11.45 bar

c. 13.66 bar

b. 10.05 bar

d. 14.43 bar

77. From PVn = C, the process is isochoric if n equals a. 0

c. 1

b.δ

d. ∞

78. To obtain the integrated form of Clausius -Clapeyron equation, from the exact Clapeyron equation, it is assumed that: a. The volume of the liquid phase is negligible compared to that of the vapor size. b. The vapor phase behaves as ideal gas. c. The heat of vaporization is independent of temperature. d. All the above are applicable. For numbers 79 to 80: One mole of an ideal gas undergoes the following sequence of mechanically reversible processes in a closed system: from an initial state of 70 0C and 1 bar, it is compressed adiabatically to 150 0C, it is then cooled from 150 to 70 0C at constant pressure and finally, it is expanded isothermally to its original state. 79. Calculate W for the entire process. Take Cv = 3R/2 and Cp = 5R/2. a. -168 J

c. 168 J

b. 0 J

d. 237 J

80. If the processes are carried out irreversibly but so as to accomplish exactly the same changes of state  – the same changes P, T, U and H then different values of Q and W. Calculate W if each step is car ried out with an efficiency of 80%. a. 168 J

c. 1996 J

b. 883 J

d. 0 J

81. During an adiabatic, internally reversible process, what is true about the change in entropy? a. it is temperature dependent

c. it is always less than zero

b. it is always zero

d. it is always greater than zero

82. Nitrogen flows through a steady state through a horizontal, insulated pipe with inside diameter of 1.5 in. A pressure drop results from flow through a partially opened valve. Just upstream from the valve the pressure is 100 psia, the temperature is 120 0F, and the average velocity is 20 ft/s. If the pressure just downstream from the valve is 20 psia, what is the temperature? a. 1190F

c. 1320F

b. 1060F

d. 1280F

83.  A 1500-kg automobile traveling at 30 m/s is brought to rest by impacting a shock absorber composed of a piston with small holes that moves in a cylinder containing water. How much heat must be removed from the water to return it to its original temperature? a. 235 kJ

c. -19kJ

b. 675 kJ

d. 898 kJ

84. Steam undergoes isentropic expansion in a turbine from 5000 kPa and 400 0C (entropy = 6.65 kJ/kg K) to 150 kPa (entropy of saturated liquid = 1.4336 kJ/kg K, entropy of saturated vapor = 7.2234 kJ/kg K). The exit condition of steam is a. superheated vapor

c. partially condensed vapor with quality of 0.9

b. saturated vapor

d. partially condensed vapor with quality of 0.1

85. It is desired to supply steam in sauna bath 20 meters above sea level initially at a temperature and pressure are 3000C and 500 kPa. The outlet steam supplied to the bath house is at 200 0C and 100 kPa to compensate heat losses along the pipe line. As such, the outlet velocity of steam must be four time as fast as the inlet steam velocity to neglect heat losses. If 10 kW pump is available, calculate the mass flow rate of steam to be supplied from a 5 cm pipe diameter. PROPERTIES OF STEAM T (0C)

P (kPa)

H (kJ/kg)

Vx104 (m3/kg)

300

500

3064.2

522.4

200

100

2875.3

2172.0

a. 0.08 kg/s

c. 0.31 kg/s

b. 0.16 kg/s

d. 0.62 kg/s

86.  An ideal gas is adiabatically and irreversibly compressed from 3 bar and 300 K to 6 bar in a closed system. The work is required for the irreversible compression is 1.5 times the work that is required for reversible compression from the same initial temperature and pressure to the same final pressure. The molar heat capacity of the gas at constant volume is 30 J/mol-K (assumed to be independent of temperature). Calculate the temperature of the gas at the final state in the irreversible compression case. a. 420 K

c. 501 K

b. 373 K

d. 286 K

87. Steam at 300 0C and 2 MPa enters a nozzle with an inlet diameter of 5 cm at a steady flowrate of 0.5 kg/s. If heat is lost at a rate of 10 kJ/s and leaves the nozzle at 200 0C and 1.4 MPa, determine the outlet diameter of the nozzle. T (0C)

P (MPa)

300 200

2 1.4

Specific Volume (m3/kg) 0.12547

a. 1.2 cm

c. 2.0 cm

b. 1.6 cm

d. 2.4 cm

Enthalpy (kJ/kg) 3023.5 2803.3

Entropy (kJ/kg-K) 6.7664 6.4975

88. The designer of a new type of engine claims an output of 225 hp with a fuel that releases 19250 BTU/lb when burned. If the heat is supplied and rejected at average temperatures of 7500F and 1450F, respectively, estimate the lowest necessary amount of fuel for the rated output of the engine? a. 30 lb/hr

c. 40 lb/hr

b. 50 lb/hr

d. 60 lb/hr

For numbers 89 – 91:  An Otto cycle has a compression ratio of 9.5. The air is at 100 kPa, 17°C, and 600 cm³ prior to the compression stroke. Temperature at the end of isentropic expansion is 800 K. Using constant specific heat, calculate the following: 89. Highest temperature in the cycle a. 1763 K

c. 1969 K

b. 1654 K

d. 1892 K

90. Thermal Efficiency a. 59.4%

c. 62.8%

b. 47.1%

d. 36.7%

91. Mean effective pressure a. 609 kPa

c. 547 kPa

b. 718 kPa

d. 425 kPa

For numbers 92 – 93: In a Rankine cycle, steam at 6.89 MPa, 516 0C enters the turbine with an initial velocity of 30.48 m/s and leaves at 20.68 kPa with a velocity of 91.44 m/s. Mass flow rate of the steam is 136078 kg/hr.  At 6.89 MPa and 5160C: H = 3451.16 kJ/kg

S = 6.86 kJ/kg-K

 At 20.68 kPa: Hv = 2610.21 kJ/kg

Hl = 254.43 kJ/kg

Sv = 7.9 kJ/kg-K

Sl = 0.841 kJ/kg-K

Vv = 7.41 m 3/kg

Vl = 1.02x10-3 m3/kg

92. Compute the thermal efficiency of the cycle. a. 41%

c. 22%

b. 37%

d. 53%

93. What is the net power produced in hp? a. 60000 hp

c. 50000 hp

b. 40000 hp

d. 30000 hp

94. The path followed in a vapor power cycle is a. boiler – condenser – turbine – pump

c. boiler – turbine –- condenser – pump

b. boiler – pump – turbine – condenser

d. boiler – pump – turbine – condenser

95. The only process which is different in Carnot and Rankine cycle is a. compression in pump

c. heat rejection process

b. expansion in turbine

d. heat addition process

96. Work output of turbine is __ the work input to the pump a. less than

c. equal to

b. greater than

d. less than or greater than

For numbers 97 to 100: Consider an air standard Diesel cycle. At the beginning of compression, the temperature is 300 K and the pressure is 101.35 k Pa. If the compression ratio is 15 and during the process 1860 kJ/kg of air as added as heat, calculate the following: 97. The maximum cycle pressure a. 3726 kPa

c. 5890 kPa

b. 1109 kPa

d. 4495 kPa

98. The maximum cycle temperature a. 1680 K

c. 3300 K

b. 2740 K

d. 4050 K

99. The thermal efficiency of the cycle a. 55%

c. 60%

b. 50%

d. 45%

100.The MEP a. 2600 kPa

c. 1300 kPa

b. 800 kPa

d. 2900 kPa