QuizBowl Questions

NO QUESTION A 1 A valve that controls flow by means of a disk or wedge-shaped gate valve dam sliding at right angles to the direction of flow and seating tightly in the valve body is a 2 The friction factor for flow through a pipe with relative roughness 0.05 of 0.004 at a Reynold's No. of 80,000 is approximately equal to

B butterfly valve

3

The equation that relates friction factor and Reynold's No., smooth pipes f=64/Reynold's No. holds for Oil flows under laminar conditions inside a steam heated copper equal to the pipe. The overall heat transfer coefficient is approximately heat transfer coefficient of the oil

laminar and turbulent flow the average between the heat transfer coefficient of the steam and that of oil

5

In multi-stage liquid-liquid extraction with partially miscible solvents

the extraction must be done to form cocurrently in order to minimize the extraction.

the minimum number of stages occur when the operating lines are parallel.

6

The enrichment of the vapor steam as it passes through the column in contact with the reflux during distillation is called The maximum number of plates for a given distillation system is obtained at The correct unit for the specific rate constant for the reaction A--->B determined to be first order is

evaporation

stripping

variable reflux

maximum reflux

square liter/square mol/min large effect

square liter/square mol/square min little effect

4

7 8 9

10

11

12 13 14

On one side of a heat exchanger where either a condensing vapor or a boiling liquid is present, the temperature may be assumed to be constant. In determining the logarithmic mean temperature difference the direction of flow will have For a cylinder where steady-state radial heat transfer takes place

A plate holding a pool of liquid from which rises a vapor whose average composition is in equilibrium with a liquid whose composition is the average of that of the liquid leaving the plate is called Crystallization occurs in a solution that is Mass transfer in a flowing fluid may be correlated by The ratio of the average diameter of the feed to the average diameter of the product is the

0.03

the heat flux is maximum heat constant transfer rate occurs at the surface separation plate theoretical plate

concentrated Sherwood, Nusselt and Reynold's No settling ratio

unsaturated Peclet, Reynold's and Schimdt No discharge ratio

15

16 17

18 19

20

21 22 23 24 25

26 27 28 29 30

The rate of formation of C for the reaction 2A + B ---> C is found the rate of to be rate=k(A)(B) formation of C is equal to the rate of disappearance of B A device for increasing the velocity of a fluid in steady flow is a nozzle In steady-state backmix flow reactor, composition is not constant throughout the reactor

the order of reactio is zero

The amount of money obtainable from the sale of used property net value over and above any changers involved in removal and sale is called In fractionation, an increase in reflux ratio increases the number of theoretical plates In mass transfer where the solute in the gas phase is very the ratio of soluble in the liquid phase liquid phase resistance to the overall resistance is close to unity

salvage value

Heat transfer in turbulent flow may be described through an empirical equation correlating

Nusselt, Stanton and Reynold's Nos Which of the following fittings exhibits the highest pressure drop 90-degree long for the same flow conditions? radius elbow A chamber into which steam from a high pressure line can be switching bank bled during periods of low steam demand from the power plant is called Which one of the following pipes has the highest relative 2" diameter roughness? Wrought iron pipe In steady-state heat transfer through a series of materials with decreases varying resistances, the heat transfer rate towards the direction of heat transfer

Nusselt, Prandtl and Reynold's Nos 90-degree standard elbow vent

Reactions whereby reactants proceed along several paths and give different products are Which one among the following materials has the best insulating property? An operation where warm vapor mixture is cooled such as by contact with a liquid resulting in condensation and decreased humidity is The pressure exerted on a plane parallel to the direction of flow of a moving fluid is called For mass transfer to take place, there must be a

polymeric reactions window glass

reversible reactions wood

evaporation

dehumidification

vent constant throughout the reactor

decreases the reboiler duty

the gas phase resistance is approximately equal to the total resistance

4" dia Wrought iron pipe varies with the thermal conductivity of each material

gauge pressure velocity pressure phase change

reaction component

31

32 33 34

35 36 37

38

39 40

41 42 43

44 45

Water vapor condenses at 1 atm on a tube whose surface tmeperature is at 80 deg F. in analyzing the heat transfer through the condensate film, it is best to evaluate the liquid properties at The diffusity of water in air at 100 deg F in sq.cm./sec is A fluid flowing at a rate of 25 cubic meters per hour inside a 60 mm I.D. pipe has an average velocity in meter per sec equal to An equimolar mixture of benzene and toluene is subjected to a single batch distillation. Distillation is discontinued when 60% of the benzene in the feed is distilled. At this instance the bottom product when analyzed shows benzene to be 36.4 mole%. In the distillate, the mole% of benzene is When 32 kg of methane is burned completely the theoretical oxygen required is The standard heat of reaction for the production of water gas, in kcal/gmole, as given by the equation: C(s) + H2O(g) = CO(g) + H2(g) is A rectangular duct 4 ft x 1.5 ft in cross section carries conditioned air. In determining the pressure drop through the duct the equivalent diameter in ft may be used which in this case is A gas decomposition reaction has an activation energy of 245 kJ/mol. The rate of reaction can be accelerated by using a platinum catalyst where the activation energy for the resulting catalyzed reactions is lower at 136 kJ/mol. Using Arrhenius' law and assuming the frequency factor remains the same the catalyzed reaction is faster than the original reaction by a factor of

212 deg F

80 deg F

0.26 5.9

0.28 2.5

66.6

58.1

16 kg

64 kg

32.2

31.4

4

2.18

Water at 100 deg F is flowing through a straight 4-in Sch 40 pipe at a rate of 1.0 gal/min. The length of the pipe is 10 ft. The velocity at the center of the pipe in ft per sec is A metallic rod 2 cm in diameter is used as a heating element. The thermal conductivity is 370 J/sec.sq.m.degC. The surface temperature is maintained at 200 deg C. For the center of the rod not to exceed 500 deg C, the maximum volumetric heat generation rate within the metallic rod in J/sec cu.m. must be This is a steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapor-gas mixture. Air, supplied at the rate of 1200 cfm to a refrigerated coil, has a relative humidity of 20% and dry bulb temperature of 150 deg F. The mass flow of dry air entering per minute is In adiabatic humidification, it is possible to maintain the temperature of water constant since

0.04

0.05

4440000

5130000

wet-bulb temperature

dew point

74.3

75

An air-carbon tetrachloride vapor mixture at 100 deg F dry bulb and 60 deg F wet bulb is heated until the temperature reaches 180 deg F. the final percent relative humidity is about The portion of water in the wet solid that cannot be removed by the air in its contact is called

0.1

0.05

free moisture

final moisture content

over 100,000 over 100 but but less than a less than 200 million

according to the the system can phase rule, the be well insulated degrees of from the freedom is 3 surroundings

46 47

48 49

50

51 52

This type of drier is used for drying pasty materials such as wet filter cakes and lumpy solids In the constant-rate period, the rate of drying is established by

rotary drier

flash drier

a balance of the heat requirements for evaporation and the rate at which heat reaches the surface

the internal movement of moisture beneath the surface of the solid

Unbound moisture in granular and porous solid moves through the intertices of the solid by a mechanism involving Wet solid is to be dried from 40% to 10% in 5 hours under constant drying conditions. The critical moisture content is 20% and the equilibrium moisture content is 7%. All moisture contents are on dry basis. The time needed to dry from 15% to 5% free moisture under the same drying conditions is If the rate of drying under constant drying conditions with air at 140 deg F and absolute humidity of 0.03 lb water per lb dry air of unknown mass of solid is given by R=0.5-exp(-60X) [in lb water/hr-sqft], then the equilibrium moisture content (db) of the material is In drying at the falling rate period, the rate at which moisture is removed from the solid material The major problem in diffusion is to promote diffusion of the solute out of the solid and into the liquid. The most effective way of doing this is

desorption

surface tension

0.542 hrs

1.846 hrs

0.12

0.03

remains constant to reduce the solid to the smallest size feasible 0.3

increases with time to use counter current operation

53

A slurry flaked soybeans weighing 100 kg contains 75 kg inert solids and 25 kg of solution 10 weight % oil and 90% wt solvent hexane. This slurry is contacted with 100 kg pure hexane in a single stage so that the value of retention for the outlet underflow is 1.5 kg of insoluble solid per kg solvent in the adhering solution. The composition of underflow leaving the extraction stage in %wt oil is

54

Tung meal containing 55% oil is to be extracted at the rate of 3 4000 lb per hour using n-hexane containing 5% oil as solvent. A countercurrent mulitple stage extraction system is to be used. The meal retains 2 lb of solvent per pound of oil free meal while the residual charge contain 0.11 lb oil per lb oil free meal while the product is conposed of 15% oil. The theoretical number of ideal stages is

4

55

The movement of molecules over a substantial distance is associated with the transfer of heat by The mode of heat transfer that can take place in a vacuum is known as The overall conductance for a composite material in series is equal to the

convection

conduction

convection

conduction

sum of the individual conductances boiling

sum of the individual conductivities condensation

56 57 58

Film and drop are terms associated with

0.8

59

A 6-in Sch 80 steel pipe is carrying glycerin at an average 99.95 temperature of 100 deg F. The pipe is uninsulated, and the outside temperature is 30 deg F. The inside film conductance is 1000 Btu/h-ft-degF while the outside film conductance is 3.0 Btu/h-sq.ft.-degF. Determine the heat lost [Btu] per minute from a 75-ft length of the pipe. Glycerine is flowing at 800 gpm. An oak (k=0.096 Btu/h-ft-degF) door, 30 in wide, 78 in high, and 97 2 in thick, has 9 glass (k=0.45 Btu/h-ft-degF) windows, each 6 in by 8 in by 1/4 in thick. Determine the amount of heat lost [Btu] each day with a surface-to-surface temperature difference of 80 deg F. Determine the length needed for a simple concentric-tube, 185.5 m parallel flow heat exchanger to transfer heat from hot water to cold water at a rate of 900 W. The heat exchanger consists of two Type K copper (k=386 W/m-degC) tubes. The smaller tube has an inside diameter of 49.8 mm and an outside diameter of 54.0 mm. Assume that both film coefficients are equal to 100 W/sq.m.-degC. The hot water enters at 90 degC and leaves at 50 degC, and the cold water enters at 10 degC and leaves at 40 degC.

415.7

A saturated solution containing 1500 kg of potassium chloride at 4301 kg 360 K is cooled in an open tank to 290K. If the specific gravity of the solution is 1.2, the solubility of potassium chloride per 100 parts of water is 53.55 at 360K and 34.5 at 290K, calculate the amount of crystals obtained assuming that loss of water by evaporation is negligible. An evaporator, working at atmospheric pressure, is to 55.8 sq.m. concentrate a solution from 5% to 20% solids at the rate of 1.25 kg/s. The solution which has a specific heat of 4.18 kJ/kg-K is fed to the evpaorator at 295K and boils at 380K. Dry saturated steam at 240 kPa is fed to the calandria and the condensate leaves at the temperature of the condensing steam. If the heat transfer coefficient is 2.3 kW/sq.m-K, what is the required area of heat transfer surface. The latent heat of vaporization maybe taken as the same as that of water.

1500 kg

64

2.5 kg/s of a solution at 288K containing 10% dissolved solids is 115 kPa fed to a forward-feed double effect evaporator operating at a pressure of 14 kPa in the last effect. If the product is to consist of a liquid containing 50% by weight of dissolved solids and dry saturated steam is fed to the steam coils, what should be the pressure of the steam? The surface in each effect is 50 sq.m. and the coefficients for heat transfer in the first and second effects are 2.8 and 1.7 kW/sq.m.-K respectively. Assume that the concentrated solution exhibits a boiling point rise of 5 degK, that the latent heat has a constant value of 2260 kJ/kg and that the specific heat of the liquid stream is constant at 3.75 kJ/kgK.

101.3 kPa

65

An acetone-air mixture containing 0.015 mol fraction of acetone 10.92 has the mol fraction reduced to 1% of this value by countercurrent absorption with water in a packed tower. The gas flow-rate G is 1 kg/sq.m-s of air and the water entering is 1.6 kg/sq.m-s. For this system, Henry's law holds and Ye=1.75x, where Ye is the mol fraction of acetone in the vapour in equilibrium with a mol fraction x in the liquid. How many overall transfer units are required?

9.12

60

61

62

63

242

11.02 m

58.5 sq.m.

66

A still has a liquor composition of ortho-xylen 10%, meta-xylene 37 65%, para-xylene 17%, benzene 4%, and ethylbenzene 4%. How many plates at total reflux are required to give a product of 80% meta-xylene and 14% para-xylene? The data are given as mole percent. A mixture of alcohol and water with 0.45 mol fraction of alcohol 10 is to be continuously distilled in a column so as to give a top product of 0.825 mol fraction alcohol and a liquor at the bottom with 0.05 mol fraction alcohol. How many theoretical plates are required if the reflux ratio used is 3? Prepared cottonseed meats containing 35% extractable oil are 72.2 fed to a continuous countercurrent extractor of the intermittent drainage type using hexane as solvent. The extractor consists of ten sections, the section efficiency being 50%. The entrainment, assumed constant, is 1 kg solution/kg solids. What will be the oil concentration in the outflowing solvent if the extractable oil content in the meats is to be reduced to 0.5% by weight?

38

69

0.4 kg/s of dry seashore sand, containing 1% by weight of salt, 0.49 is to be washed with 0.4 kg/s of fresh water running countercurrent to the sand through two classifiers in series. Assume that perfect mixing of the sand and water occurs in each classifier and that the sand discharged from each classifier contains one part of water for every two of sand (by weight). If the washed sand is dried in a kiln drier, what percent of salt will it retain?

0.43

70

Forty-five pounds per minute of water is heated from 60 to 180 2173 deg F in a 5/8 in., 16 BWG heat exchanger tube. If the steam condensing at 260 deg F, on the outside of the tube gives an h о of 1000 Btu/hr-sq.ft.-degF, calculate the inside heat transfer coefficient [Btu/hr-cu.ft-degF]. How many cu.ft. per minute of entering air is needed to 12.54 evaporate 10 lb of water per hour from a rayon, if the air enters at 80 deg F and 25% humidity and leaves at 170 deg F and 55% relative humidity. The operating pressure is 14.3 psia.

696

Nicotine is to be extracted from water using kerosene. If 100 lb 64.5 of a 2% nicotene solution is extracted once with 200 lb of kerosene, what percent of the nicotene is extracted? {Equilibrium data: Y[lb nicotene/lb kerosene] = 0.90X [lb nicotene/lb water]} We must cool 2500 gpm of water from 120 to 80 deg F. A 77.2 cooling tower, at 70 deg F and 1 atm, is to be designed to operate with entering air of 40% relative humidity. How many gpm of makeup water must be supplied if windage loss is 95% of the amount lost by evaporation. We wish to build an economical cold room 20 ft square and 10 ft 3537 high. The outside temperature is 80 deg F and te room is to be maintained at 0 deg F. The boss has suggested parallel wooden outer and inner walls separated by a 6-in air space. What will be the heat loss [Btu/hr] through each wall?

54.6

67

68

71

72

73

74

9

28.7

12.68

150

8457

75

A colloidal solution is to be concentrated from 15 to 65% solids. 10500 The specific heat of the feed, entering at 50 deg F is 0.93. The pressure of the saturated steam to the evaporator is 10 psia; the condenser pressure is 5-in. Hg abs. The steam chest has an overall heat transfer coefficient of 200 Btu/hr-sq.ft.-degF. Water must be evaporated at the rate of 35,000 lb/hr. Neglecting boiling point elevation, what is the steam consumption [lb/hr]?

35000

76

What is the settling time [sec] for galena particles to settle under free settling conditions through 5 ft of water at 50 deg F. Galena is spherical in shape, with specific gravity and 0.01 inch in diameter. A 10-ft diameter tank with a quick-opening value to a sump has a 10-ft depth of liquid. How long [t in sec] does it take to drain the tank if the valve is assumed to be equivalent to a 4-in diameter orifice? The liquid density is 60 lb/cu.ft. What size sharp-edged orifice [inches] was in use if a flow of 120 gpm produced a 4-in Hg differential in a 4-in Schedule 40 pipe. The fluid, measured at 60 degF, had a viscosity of 1 cSt and a specific gravity of 1. Seven hundred gallons per minute of water are being discharged by a centrifugal pump 5 ft above the pump inlet. The inlet pressure is 4-in Hg above atmospheric and the discharge pressure is 29 psia. If the pump has an 8-inch diameter inlet and a 4-inch diameter discharge, calculate the pump efficiency.

38.1

18.3

2951

1644

2.21

1.35

63

84

77

78

79

80

Determine the net positive suction head available to a centrifugal 34.2 pump when the level of water is just at the suction point. The pumped fluid is water at 140 deg F and it is pumped from an atmospheric tank at 250 gpm. The tank suction point is 7 ft above the pump. The piping is 5-in Schedule 40, 10-ft long with two short radius 90 deg elbows. [Use density=61.38 lb/cuft, Pv=2.89 psi, viscosity=0.47 cP]

27.7

81

Water at 60 deg F flows through a 3-inch Schedule 40 pipe. A pitot tube in the pipe shows a 3-inch Hg differential. If the pitot tube is located at the center of the pipe, what is the mass flow rate of the water [lb/s]? The gas phase irreversible reaction A+B---->C is elementary. The entering flow rate of A is 10 mol/min and is equal molar in A and B. The entering concentration of A is 0.4 mol/L. What CSTR volume [L] is necessary to achieve 90% conversion? The irreversible zero order gas phase dimerization 2A ----->A2 is carried out in a packed bed reactor with 5 kg of catalyst. The entering pressure is 10 atm and the exit pressure is 1 atm. Pure A enters at a flow rate of 10 mol/min. The reaction is zero order in A. What is the exit conversion? The gas phase reaction 2A+B----->C is carried out in a PFR. The feed is equal molar in A and B and the entering temperature is 500K and the entering pressure is 16.4 atm. If the exit conversion is x, then the exit concentration of B is

11.61

14.24

113

227

0.15

0.5

82

83

84

[B]=0.4(1-x)/(1- [B]=0.4(1-x)/(10.5x) 1.5x)

85

Heat is generated in a 2.5 cm square copper rod at the rate of 75.2 35.3e6 W/cu.m. The rod is exposed to a convection environment at 20 deg C where the convection heat transfer coefficient is 4 kW/sq.m.-degC. Determine the surface temperature [deg C] of the rod. A 5cm diameter cylinder is maintained at a constant temperature 13 of 200 deg C and it is "completely enclosed" by a wind tunnel test chamber, walls of which are at 10 deg C. Air at 350K is forced across the cylinder at a velocity of 50 m/s (h=180 W/mdegC). If the surface emissivity of the cylinder is 0.7, determine the total (i.e., convective and radiative) heat transfer from the cylinder [W per meter length].

55.2

87

A building wall consists of a 6-in of concrete (kc= 0.7 Btu/hr-ft0.03 degF), 2 in of fiber insulating board, and 3/8 in of gypsum board (kg=0.03 Btu/hr-ft-degF). The inside and outside heat transfer coefficients are 2 and 7 Btu/hr-sqft-degF, respectively. The inside temperature is 72 degF and the outside temperature is 20 degF. Determine the overall heat transfer coefficient for this wall [Btu/hr-sqft-degF].

0.12

88

Current is passed through a cylindrical laboratory heater, which 325 has a 3 cm diameter, generating heat at the rate of 20 MW/cu.m. The heater is exposed to a convection environment at 25 degC where the convection heat transfer coefficient is 0.5 kW/sq.m.-degC. Determine its surface temperature [degC]. A straight rectangular fin has a length of 3.5 cm, a thickness of 1500 W 1.5 mm, and is made of a material characterized by thermal conductivity of 255 W/m-degC. The fin is exposed to a convection environment at 20 degC and h=1.5 kW/sq.m.-degC. Determine the maximum possible heat transfer from this fin for the base temperature of 150 degC. A gaseous fuel is composed of 20% methane( CH4), 40% 1 ethane (C2H6) and 40% propane (C3H8), where all percentages are by volume. The volumetric analysis of the dry products of combustion (ie. everything except the water) for this fuel gives 10.6% carbon dioxide (CO2), 3% oxygen (O2), 1% carbon monoxide (CO) and 85.4% nitrogen (N2). Determine the air fuel ratio on a mass basis for this reaction.

300

Dodecane (C12H26) gas at 25 degC is burned in a steady flow combustion chamber with 20% excess air that enters at -23.15 degC. The products leave the combustion chamber at 500K. Assuming steady operating conditions and complete combustion, determine the required mass flow rate of the dodecane to supply heat at a rate of 1.5 kW [kg/s]. Two rooms A and B of identical volume are connected by an open doorway. The thermostat in the rooms are set so that Ta B+C is second order, which of the following plots will give a straight line?

the temperature dependency of the rate depends on the depends on the initial conc of conc of one of the reactants the products at equilibrium 2 4 conc of the reactants 0 log Ca vs time

molecularity of the reaction 2 Ca vs time

Ca^2 vs time

1/Ca vs time

126 For the reaction A+B ---> 2C, when Ca is doubled the rate doubles, when Cb is doubled the rate increases fourfold. The rate law is 127 It states that the rate of a chemical reaction is proportional to the activity of the reactants. 128 The half life of a material undergoing second order decay is 129 A fluid flows through 2 CSTR in series. Each reactor has a capacity of 400,000 L and the fluid enters at 100 L per hr. The fluid undergoes a first order decay with a half life of 24 hours. Find the conversion of the fluid. 130 A first order reaction has a specific rate constant of 3e-3 per sec. The half life is 131 A certain reaction is 1st order in A. In 30 min, the concentration of A decreases from 0.55 to 0.15 mol/L. The time it will take for A to decrease from 0.35 to 0.15 mol/L is 132 A gas decomposes at 900 degC according to 2A--->2R+S with a rate constant of 1000 cc/gmol-s using pure A. The time it will take to react 80% of A in a batch reactor at 900 degC and 1 atm in min is 133 Calculate the length of a chlorinating pipe line with diameter of 0.6 m required to kill 95% of the bacteria in waste water flowing at 0.05 cu.m/s. Test shows that 95.33% kill is obtained in 5 minutes when treated with 5 mg/L of chlorine. Chlorine disinfection kinetics is given by the equation: dC/dt = k Ct^1.5 where C = number of bacteria. Assume that the same concentration of chlorine is used in actual treatment operation.

-ra = k Ca^2 Cb^4

-ra = k Ca Cb^2

Le Chatelier's principle proportional to the square of the initial conc 66.8

Hess' Law

0.0021 s

100 s

45.1 min

19.6 min

3.83

7.43

25.36 m

32.5 m

independent of initial conc 74.7

134 The set of data given below is for the parallel reaction: a---k1-- 0.17 >2R, a---k2-->S. At t=0, Ca=15 moles/cuft, Cr = 1 mole/cuft, Cs=1 mole/cuft; At t=1 hr, Cro = 9 moles/cuft, Cs = 3 moles/cuft. The value of K2 per hour is 135 A batch reaction 2D+E----->F has a conversion factor expressed 257 by the equation r =0.24 t^0.5 where r = conversion factor based on the reactant E; t = time in hours which ranges from 0.5 to 16 hours per batch depending upon the process variables. The average molecular weight of the feed is 60 and a density of 1.4 g/cc. The feed consists of 2 kgmole of D and 1 kgmole of E. The charging, cleaning and discharging time per batch is 2.5 hrs and the volume of the reactor is twice the volume of the feed. Assume 300 days per year and 12 hours operation/day. The volume of the reactor in liters is

0.18

136 A container holds 100 gal of salt solution containing 50 lb of 0.73 dissolved salt. The bottom of the container is covered with a layer of rock salt. The bottom of the container is covered with a layer of rock salt whose surface is practically constant. The salt dissolved into the solution according to r = k(C-3) where C is the concentration of the brine expressed in lb/gal. If the water in the tank were fresh, the rate of solution would be 1.0 lb/min. Fresh water enters at 3 gpm and brine overflows at the same rate. Assume constant volume at any brine concentration, the concentration of brine in container after 1 hour in lb/gal of salt is

0.43

275

137 An aqueous solution of ethyl acetate is to be saponified with NaOH. The initial concentration of the ethyl acetate is 5 g/L and that of the caustic soda is 0.10M. Values of the second order rate constant in L/gmole-min are k = 23.5 at 0 degC; k = 92.4 at 20 degC. The reaction is essentially irreversible. The time required to saponify 95% of the water at 40 deg C is 138 At 500K the rate of bimolecular reaction is 10 times the rate at 400K. Find E in cal, the activation energy for this reaction from Arrhenius Law. 139 The reaction A+2B--->R is 1st order with respect to each reactant. If equimolar amounts of A and B are introduced into a constant-volume reactor and (1/m) th of A remains after t1, how much will remain after t2=2t1? 140 When the 1st order homogeneous reaction (gas-phase) A-->2.5R is carried out in an isothermal batch reactor at 2 atm with 20% inerts present, the volume increases by 60% in 20 min. When the reaction is carried out in a constant volume reactor, the time required for the pressure to reach 8 atm if the initial pressure is 5 atm, 2 atm of which consist of inerts in min is

10.3

11.4

8150

9150

Cao/2m

Cao/(2m-1)

43.1

41.3

141 When the ID of the pipe through which a fluid flows is doubled, the pressure loss due to friction per unit length of pipe and for the same volumetric flow rate is changed by approximately a factor of 142 When two centrifugal pumps are connected in series, the discharge changes by a factor of 143 When two reciprocating pumps are connected in parallel, the volumetric capacity of the system changes by a factor of 144 The pressure drop in a pipeline changes by a factor of _____ when the velocity of the flowing fluid is doubled. 145 Cavitation occurs in a centrifugal pump when

1/8

1/16

1/2

1

1/2

1

1/2

1

the discharge pressure becomes too high 0.63

the discharge valve is closed

1.05

1.22

0.6

3.58

PhP 3300

PhP 5000

1/2

1

146 Oil with a viscosity of 30 cP and a density of 60 lb/cu.ft. flows through a 1/2-inch inside diameter pipe. Determine the velocity in fps below which flow will be laminar. 147 Water at 60 deg F flows through a 3-inch inside diameter smooth horizontal pipe. If the Reynold's number is 353000, calculate the ratio of maximum velocity to average velocity. 148 The pressure after the pump in a 6-inch inside diameter smooth pipe conducting water is 20 psia. The water is discharged at an open tank 100 ft from the pump. Calculate the rate of discharge of water in cu.ft/s. 149 A water storage tank assumes the supply of water into a factory. Water is supplied to the tank through a booster pump installed in the water line. The theoretical pump horsepower required is 3.25 hp. What is the monthly operating cost of the pump if electric power cost on the average is PhP 3.73/kWh. The pump is 65% efficient and operates for 12 hr a day. 150 When the impeller speed of an ideal centrifugal pump is doubled, the vol. flow rate of discharge is increased by a factor of

13.1

151 The differential height between two points which a fluid has to be transferred is the 152 The resistance of a layer of fluid to flow over the next layer is measured by 153 An axial flow pump operating at a speed of 880 rpm can supply water at a rate of 3000 gpm. The maximum head that this pump can deliver in ft. of water is 154 Specify the type of open impeller pump to use if the capacity is 400 gpm at a head of 200 ft of water. 155 What will be the rated capacity [gpm] of a 4-1/2 inch impeller centrifugal pump operating at a speed of 3450 rpm capable of generating a head of 40 ft of water. 156 If the speed of a centrifugal pump is doubled, the energy requirement becomes approximately ___ times the original energy requirement. 157 A cylindrical tank 1 ft in diameter discharges through a nozzle connected to the base. Find the time needed for the water level in the tank to drop from 4 ft to 2 ft above the nozzle. The diameter of the nozzle is 1 inch and its discharge coefficient maybe taken as unity. 158 The NPSH of a single suction centrifugal hot water pump at a speed of 3550 rpm operating at a pressure of 600 psi and a capacity of 450 gpm is ___ ft. 159 The rate of evaporation at a given operating temperature in a n evaporator is more when

potential head

pressure head

viscosity

friction factor

20

36

3x2x8.5E

4x3x8.5E

95

134

2

4

32

55

15

20

160 An optimim number of the effects for a given application is a function of the 161 A popular type of heat exchanger for cooling large quantities of fluid is the 162 An evaporator is used to concentrate 10,000 lb/hr of a 20% solution of NaOH in water at 140 oF using saturated steam at 25 psia at a rate of 7,000 lb/hr. The OHTC is 275 BTU/hr-ft 2-oF when the pressure in the vapor is 1.7 psia. The steam economy, SE, is 163 A cross flow heat exchanger uses mixed air at 4 kg/s that enters at 15oC and leaves at 45 oC. The air cools unmixed water, which enters at 95 oC and 0.70 kg/s. The OHTC equals 150 W/m 2-oC. After several months of operation, a scale resistance of 0.002 m2-oC/W developed. 16. The heat transfer area required to accomplish the change is 164 As solution of 28% wt Na 2SO4 is to be crystallized to yield Glauber salt in a four section (one section is 10 ft in length) Swenson Walker Crystallizer. It is fed to the unit at 120 oF and cooled to 60 oF using cooling water which enters at 50oF and leaves at 70oF. The crystallizer has a cooling surface of 3 ft 2 per foot of length. The feed rate is 500 lb/hr and the crystallizer is seeded with 50 lb/hr of 65 mesh crystals. 19. The amount of the crystalline crop (C) produced in lb per hour is

capacity

economy

double-pipe

plate

0.82

0.86

22.2 m2

25 m2

285.3

249.3

165 An insulator should have

low thermal conductivity

high thermal conductivity

when the the operating operating pressure is low pressure is high

166 Fouling factor

is a dimensionless quantity

does not provide a safety factor for design

167 Natural convection is characterized by

Reynolds number mass transfer between a gas and a liquid clean and dirt free surfaces

Grashhoff number absorption with chemical reaction smooth clean surfaces

168 The Graetz number is concerned with 169 Dropwise condensation occurs on 170 Dietus-Boelter equation for determination of heat transfer coefficient is valid

for liquid metals for fluid in laminar flow

171 A type of pneumatic conveyor system characterized by a material moving in an air stream or pressure less than ambient.

fluidizing

pressure

172 If the total percentage of particles larger than the screen 0.98 opening in the feed, oversize, undersize are 36%, 89% and 3%, respectively, the effectiveness of the screen if the undersize is the product is 173 The estimated width of an apron conveyor having a capacity of 305 mm 75 tons/hr at a speed of 50 ft/min is 174 It is defined as the ratio of the average diameter of the feed to settling ratio the average diameter of the product.

0.89

175 The sphericity of cubical particles is 1 176 The separation of a dilute slurry or suspension by gravity settling thickening into a clear fluid and a slurry or suspension by gravity settling into a clear fluid and a slurry of higher solids content is called

0.87 classification

177 An ultracentrifuge is used to separate high-molecular weight fractions in polymeric or biological systems. What is the gradient for mass transfer in the separation using this mass transfer device? 178 Ordinary diffusion takes place because of ___ driving force. 179 What are the two limiting cases of steady-state diffusion?

pressure

180 Which of the following is not true in (binary) equimolar counterdiffusion? 181 A fluid is flowing on a surface, which contains a component that leaches out to the fluid. Assuming that all the 3 regions of mass transfer are present, in which of these regions is diffusion controlling? 182 In unsteady-state mass transfer, the quantity (D ABt/rm^2) is referred to as 183 What is the equivalent of Prandtl number in convective mass transfer? 184 If kx > ky, then the controlling phase is

temperature

610 mm screen-mesh no

temperature pressure UMD and EMD ordinary and Knudsen DAB = DBA c = cA + cB Knudsen region turbulent region

unaccomplishe relative d change resistance Sc

Sh

the liquid phase the gas phase

185 In two-phase mass transfer, equilibrium may exist

at the interface in the gas phase

186 Which of the following processes may always be regarded as a constant- humidity process?

cooling of air

air conditioning

187 Air conditioning in tropical countries involves

humidification by a process similar to that in a cooling tower

humidification by a process similar to air-water vapor saturator

188 What do you call the steady-state non-equilibrium temperature reached when a small amount of water is contacted under adiabatic conditions by a continuous stream of gas? 189 The moisture content of a solid is given as 50% wet basis. What is the moisture content, dry basis? 190 The moisture that can be removed by drying is called

dry-bulb temperature

wet-bulb temperature

0.5

1

equilibrium bound moisture moisture 191 Falling-period in drying terminates at the end of origin of R vs X constant-rate plot period 192 Which is not true at the interphase of a gas scrubbing the solute the solute operation? concentration concentration of of the gas is the liquid is less less than that of than that of the the bulk bulk -5 193 He and N2 gas are contained in a conduit 5 mm in diameter and 2.35 exp 2.44exp -5 a 0.1 m long at 298 K and a uniform pressure of He at one end of the tube is 0.6 atm and 0.02 atm at the other end. Assuming equimolar countercurrent diffusion, the flux in kmol/s-m 2 is 194 100 m3/hr of air at 60°C and 20% RH is needed for a chemical 5280 reactor. This will be obtained from process air at 60 °C and 10% RH by humidifying adiabatically the process air followed by heating to its original temperature. The wattage of the heater at 80% efficiency is

8490

195 Wet solid is to be dried from 36% to 8% moisture in 5 hr under constant drying condition. Critical and equilibrium moisture contents are 14 and 4% respectively. Calculate how much longer will it take to dry the same material from 8% to 5.5% moisture under constant drying condition. All moisture contents are on a dry basis. 196 The unit of volumetric diffusivity is 197 If reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. the reflux ratio is 198 Which of the following provides maximum contact surface for a liquid-vapour system? 199 In extraction, as the temperature increases, the area of heterogeneity (area covered by bimodal curve) 200 The suitable evaporator for concentration of foaming liquids is

1 hr

1.6 hr

cm^2/sec 0.5

cm/sec 2

packed lower

bubble-cup plate column increases

decreases

long tube evaporator 201 Macroscopic transfer of mass between moving fluid and surface molecular which is of different concentration is called diffusion

short tube evaporator unsteady-state diffusion

202 For a packed column the main purpose of packing is to

strengthen the increase the column surface area

203 In a gas absorption operation, when the operating line crosses the equilibrium curve

the NTU is zero the liquid flow rate is maximum

204 Methanol diffuses in 0.15 cm stagnant film of 1:1 mole mixture of hydrogen and CO2 at 100oC and 2 atm. The partial pressures of methanol on both sides are 0.6 and 0.2 atm. The average diffusivity of methanol in the hydrogen and CO 2 at 0 oC and 1 atm in cm2/s is 205 Gaseous reactant A decomposes according to the reaction A --> 3R (-rA = 0.5 CA mole/L-min). The feed, which consists of 70% A and 30% inert, enters a 1.5-m 3 CSTR at a flow rate of 150 L/min. 4. If CA0 = 0.30 mole/L, what is the conversion, XA? 206 Between 0 degC and 50 degC, the average activation energy of a certain reaction is 80 kJ/mol. How many times faster will the reaction occur at 300 K than at 275 K? 207 Consider a gas-phase reaction 2A ---> R + 2S with unknown kinetics. A space velocity of 0.8/min is needed for 95% conversion of A in a PFR. Find the mean residence time or holding time of the fluid in the PFR. 208 For Newtonian fluids, the shear stress is

0.15

0.31

0.92

0.86

14.7

18.5

0.54 min

0.85 min

constant.

209 An ideal fluid is one that is

compressible

inversely proportional to rate of deformation. incompressible & viscous 5.29

210 Water flows through an 8-in (ID=7.981 in) steel pipe at an 10.58 average velocity of 6 ft/s. Downstream the pipe splits into an 8-in main and a 2 in (ID=2.067 in) bypass pipes. If the velocity in the bypass is twice the velocity of the main pipe, the volumetric flow rate [ft 3/s] in the main pipe is 211 An imaginary line within a fluid flow such that a tangent at any stream tube point indicates the direction of flow at that point. 212 Air at 250C [viscosity=0.018 cP] enters a section of 2-in schedule 350 40 commercial steel pipe at a gauge pressure of 310 kPa and a flow rate of 1200 kg/h. Assuming isothermal flow, what is the pressure drop [kPa] in 60 m of pipe? 213 A simple pitot tube measures acoustical velocity 214 Which of the following meters will have the highest permanent pitot tube pressure loss? 215 In the flow meter equation, Y, indicates the mass flow rate 216 The loss due to sudden contraction is proportional to 217 Stoke’s law is valid when the particle Reynolds number is 218 Priming needed in a

velocity 1 Gear pump 37 ft globe

221 Multistage compressors are used in industry because, they

reduce the cost reduce the size of compressor requirement

222 For ideally incompressible fluid, the mach number will be 223 of the following produces maximum pressure difference for transportation of gases? 224 The fluid property which matters for falling rain drops to acquire spherical shape is its 225 A wastewater solution having a volume of 1000 L contains 0.21 kg phenol/m3 of solution. A total of 1.40 kg fresh granular activated carbon is added to the solution, which is then mixed thoroughly to reach equilibrium. What is the amount of phenol absorbed per kg carbon at equilibrium? 226 The overhead product composition decreases with time in

0 1 vacuum pumps blowers

227 228 229

230 231 232 233 234 235 236 237

pressure 0.007 kg

height of descend 0.106 kg

batch distillation continuous with reflux distillation with reflux For a binary mixture with low relativity, continuous rectification to low reflux ratio small crossget pure products will require section Chemisorption is the same as characterized by van der Waals adsorption of heat The stage efficiency in leaching depends on the time of contact rate of diffusion between the of the solute solid and the through the solid solution and into the liquid Weeping in distillation or absorption column increases tray provides larger efficiency surface for mass transfer What are the two contacting phase in leaching? extract phase solvent phase and raffinate and solute phase phase Hydrogen sulfide is removed from water by contacting the Distillation Leaching solution with warm air. The operation is Disregarding the cost, which is the best solvent for the extraction caproic acid chloroform of acetic acid from an aqueous solution at 25deg C? Professional Regulations Commission was created under P.D. No. 223 P.D. No. 233 A chemical engineer who designed and built a new type pf TRUE FALSE reactor and for three years, sold many units to the public can still patent his reactor. A person who has passed the Chemical Licensure Examination 18 19 can take his/her oath as a chemical engineer if his/her age is not less than _______ years. Which of the following is not a requirement for utility model inventive step novelty registration?

238 A section of the patent application containing detailed descriptions of the benefits obtained from using the invention is called the 239 A document issued by the DENR secretary indicating that the proposed project will cause significant negative environmental impact.

disclosure

abstract

Environmental Environmental Impact Compliance Statement Certificate

240 In the Philippines, sulfur for sulfuric acid manufacturing is sourced from _______ industry. 241 Sulfur is undesirable in petroleum because

paper

cement

it causes engine knocking

it increases the boiling pt of fuel

242 Materials added to detergent formulation to enhance cleaning performance by exhibiting synergistic cleaning effect with surfactant. 243 Polyethylene is an example of _____________ polymerization

fillers

brighteners

condensation

addition

244 Principal chemical conversion in the production of resin from monomer. 245 Carbon black is added to rubber compounding as 246 The binder for all the powder materials of paint 247 A fibrous material left after cane sugar has been milled is commonly called as 248 Molasses is a by product of raw sugar from the ______ process

condensation

hydration

activator pigment bagasse

curing agent vehicle pulp

milling

extraction

249 Kraft process is a common name for 250 Water insoluble cell binders of wood 251 DDT means

sulfate pulping pulp Diphenyldichlor otriphenylethan e decoloration pigment

sulfite pulping cellulose dichlorodiphenyl dichloroethane

254 Plasticisers are added to paints to

make it corrosion resistant

make glossy surface

255 Silicone is

thermoplastic

a monomer

256 The process involved in converting rubber into a thin sheet or coating it on fabric is called 257 Alkyl benzene sulfonate (ABS) is a 258 Neoprene is a 259 Steam enters an adiabatic turbine at 10 MPa and 500 degC at a rate of 3 kg/s and leaves at 0.1 MPa. If the power output of the turbine is 2 MW, determine the turbine efficiency. 260 Work is a

extrusion

mastication

detergent monomer 0.23

rubber synthetic rubber 0.32

261 Throttling process is

a reversible and an irreversible isothermal and constant process entropy

252 Rancidity of oil can be reduced by 253 Varnish does not contain

hydrogenation dryer

property of the path function system

262 A sample consisting of 1.00 mole of Argon gas is expanded 0 isothermally and reversibly at 0°C from 22.4L to 44.8L. The heat absorbed by the system is 263 Maximum work can be obtained from a system when the change isothermal taking place in it is

+1.13 kJ

adiabatic

264 The ratio of work performed by a system and the heat it absorbed from a reservoir is referred to 265 According to the first law of thermodynamics

Entropy

Gibb’s free energy Energy is Perpetual neither lost nor motion is gained in any possible. energy transformation.

266 In a 3-stage compressor system whose isentropic efficiencies are reported to be 0.75, 0.85 and 0.84, respectively, steam initially at 10 kPa is compressed to a final pressure of 500 kPa. The overall efficiency of the system is 267 In choosing the refrigerant, the fluid must have the following characteristics, except

greater than 0.85

268 Coolers and boilers are ordinarily operated at ________ condition. 269 For an isolated system, maximum entropy will occur at

isobaric

isenthalpic

half-life

critical condition

270 A carnot cycle consists of

two isothermal and two adiabatic process

two isochoric and two adiabatic process

in between 0.75 and 0.85

environmentally has a vapor benign pressure less than atmospheric

271 This is also known as the volume fraction of the voids in packed sphericity porosity beds. 272 A measure of the ratio of the drag force acting on a unit area of Froude number Reynold’s the impeller & the inertial stress. number 273 Sulfuric acid is pumped at 3 kg/s through a 60-m length of 3 2 smooth 25 mm pipe. If the pressure drop falls by one-half, what will be the new flow rate [kg/s]? Assume the following properties of sulfuric acid: SG = 1.84, viscosity = 25 cP. 274 The equation del(P) = -(rho)(g) del(z) is known as the hydrostatic shear forces fluid is vertical law for which all the following assumptions are applied, are not involved incompressible except 275 Which of the following can be adjusted by human operator in a closed feedback control loop? 276 The thermocouple is based on the Seebeck effect which states that a/an _____ is generated when opposite junction of certain dissimilar pairs of wires are exposed to different temperatures. 277 Dead time is a function of distance and

set point

controller output

current

temperature

momentum

acceleration

278 A pneumatic controller is used to control temperature within the 2.83kPa/K range 280K to 310K. The controller is adjusted so that the output pressure goes from 20kPa (valve fully open) to 105 Kpa (valve fully closed) as the measured temperature goes from 295K to 300K with the sent point held constant. What is the proportional gain? 279 The parameter which completely describes the behavior of the Time constant response to a disturbance of a second order system is the 280 Water is flowing through a 3-inch schedule 40 pipe at 60 deg F. 11.61 ft/s A pitot tube is inserted at the centerline of the pipe and registers a 3-inch Hg differential. What is the mass flow rate of the water?

0.35kPa/K

281 An oil well is 1200 ft below ground level. Oil at 500 psig at the bottom flows to ground level through a 12-inch schedule 80 commercial steel pipe. The oil has a SG of 0.86 and viscosity of 8 cP. The vol flow rate of oil in barrels per hour is 282 The equivalent diameter of a concentric annular space where 1inch OD pipe is located inside a 2-inch ID pipe is 283 Based on Bond's crushing law, the power required to crush a certain material will change by _____% if the diameter of the product is made smaller by 50%. 284 The BPR of a 50% NaOH solution at an evaporator pressure of 4.7 psia is

9365

9461

pi/4 inch

1 inch

20.2

41.4

73 degF

173 degF

damping coefficient 37.1 kg/s

C globe valve 0.03

D orifice

laminar flow only equal to the heat transfer coefficient of the steam

the minimum number of stages occur when the tie line coincides with an operating line.

the amount of solvent used must be enough to form 2 phases.

rectification

fractionation

minimum reflux optimum reflux

no effect

1

o

0

d

1

o

0

b

1

c

1

c

1

o

0

o

0

c

1

d

1

c

1

o

0

c

1

liter/mol/min significant effect

the heat transfer is constant

the temperature is uniform throughout the cylinder transition plate bubble plate

supersaturated Sherwood, Reynold's and Schimdt No reduction ratio

a 0.04

turbulent flow only equal to the heat transfer coefficient equivalent to the resistance offerred by the pipe

mol/liter/min

ANSWER SCORE

saturated Prandtl, Schimdt and Reynold's No classification ratio

the value of k is the reaction independent of cannot proceed the initial concentrations of A and B orifice a function of time

book value

venturi not uniform throughout the reactor and varies from time to time market value

increases the amount of distillate

increases the condenser duty

the gas phase resistance is negligible

the ratio of gas phase resistance to liquid resistance is approximately zero

Peclet, Stanton Schimdt, Peclet and Prandtl Nos and Friction Nos 45-degree square-corner standard elbow elbow compressor accumulator

c

1

a

1

b

1

b

1

o

0

o

0

o

0

d

1

b

1

1" dia Drawn tubing

4" dia Riveted steel pipe

d

1

through each material is inversely proportional to the thickness of the material parallel reactions air

is constant throughout the series of materials

d

1

c

1

b

1

humidification

extraction b

1

o

0

c

1

tangential pressure concentration gradient

consecutive reactions concret

static pressure momentum gradient

113 deg F

146 deg F 0

1.48 1.5

0.58 0.6

33.4

54.4

0 0

0 128 kg

32 kg

26.4

57.8

0 0

1.5

2.75 0

over 20 million over 2 but less than 3 0

0.05

0.03 0

6930000

2040000 0

saturation temperature

dry-bulb temperature

75.26

78.5

a

1 0

the temperature of the air can also be maintained constant 0.02

increase in the humidity of the air is insignificant

b

1

0.01 0

equilibrium moisture content

critical moisture content

c

1

tray drier

freeze drier

air flow air flow parallel perpendicular to to the solid the surface of surface the solid

surface renewal moisture diffusivity 2.129 hrs 3.42 hrs

c

1

a

1

d

1

0 0.01

0 0

decreases with time to use cross flow evaporation

no drying takes place to use spray percolators

1.5

2.3

c

1

a

1

0

5

6 0

radiation

all of A, B and C radiation all of A, B and C inverse of the sum of the total resistance individual resistances evaporation all of A, B and C

a

1

c

1

c

1

b

1

451.7

475.1 0

5800

139200 0

5.51 m

4.14 m

0

966 kg

534 kg 0

85.8 sq.m.

88.5 sq.m.

0

14 kPa

zero gauge

0

4.72

3.03

0

39

40 0

8

7 0

27.8

22.7

0

0.29

0.25

0

577

241 0

13.76

16.28 0

46.5

45.6 0

227.2

300 0

11994

20451 0

40130

45500

0

13.8

5 0

1163

19.4 0

4.67

2 0

95

100 0

7

0.52 0

31.7

37.1 0

851

900 0

0.75

1 0

[B]=0.4(10.5x)/(1-x)

[B]=0.2 0

25.2

20 0

3478

3750 0

0.71

6.01 0

100

25 0

13943 W

19343 W 0

23

33 0

38

0.04 0

both contain the same no of air molecules increases by decreases. about 40% stays constant. stays the same. may increase or decrease.

a

1 0

c

1

a

1

The application should be rejected because it violates both 1st and 2nd laws of Thermo.

The application should be given full consideration because it does not violate any laws of Thermodynami cs.

increases 8x.

increases 16x.

0

0

3 e7

5.2 e8 0

excess reactant product yield reactant ratio Latent Heat of Condensation moisture Ultimate analysis O2-free basis Dulong's formula 32.48 2.38

fresh-feed conversion Net Calorific Value volatile combustible matters Elemental analysis N2-free basis Oxygen unaccounted for equation 42.56 6.13

b

1

b

1

a

1

b

1

a

1

b

1

c

1

a

1 0

absolute 60% saturation humidity of 0.05 PhP 434.16

a

1

PhP 450 0

0.03

0.05 0

4350

6000 0

9.5

17 0

0.9

0.92 0

51.2

22.76 0

7.86

23.1 0

1/conc 2

0

1/conc-time 1.5

adding a catalyst

removing the products of the reaction the net equation the rate law. does not depend on the initial concentrations 8

is not a characteristic of the reaction

nature of reactants >0 log Ca vs reciprocal time lof Ca vs time

temperature

0 c

1

d

1

c

1

16

2R+S with a 3.83 rate constant of 1000 cc/gmol-s using pure A. The time it will take to react 80% of A in a batch reactor at 900 degC and 1 atm in min is

133

Calculate the length of a chlorinating pipe line with diameter of 0.6 25.36 m m required to kill 95% of the bacteria in waste water flowing at 0.05 cu.m/s. Test shows that 95.33% kill is obtained in 5 minutes when treated with 5 mg/L of chlorine. Chlorine disinfection kinetics is given by the equation: dC/dt = k Ct^1.5 where C = number of bacteria. Assume that the same concentration of chlorine is used in actual treatment operation.

134

The set of data given below is for the parallel reaction: a---k1-->2R, 0.17 a---k2-->S. At t=0, Ca=15 moles/cuft, Cr = 1 mole/cuft, Cs=1 mole/cuft; At t=1 hr, Cro = 9 moles/cuft, Cs = 3 moles/cuft. The value of K2 per hour is

135

A batch reaction 2D+E----->F has a conversion factor expressed by 257 the equation r =0.24 t^0.5 where r = conversion factor based on the reactant E; t = time in hours which ranges from 0.5 to 16 hours per batch depending upon the process variables. The average molecular weight of the feed is 60 and a density of 1.4 g/cc. The feed consists of 2 kgmole of D and 1 kgmole of E. The charging, cleaning and discharging time per batch is 2.5 hrs and the volume of the reactor is twice the volume of the feed. Assume 300 days per year and 12 hours operation/day. The volume of the reactor in liters is

136

A container holds 100 gal of salt solution containing 50 lb of 0.73 dissolved salt. The bottom of the container is covered with a layer of rock salt. The bottom of the container is covered with a layer of rock salt whose surface is practically constant. The salt dissolved into the solution according to r = k(C-3) where C is the concentration of the brine expressed in lb/gal. If the water in the tank were fresh, the rate of solution would be 1.0 lb/min. Fresh water enters at 3 gpm and brine overflows at the same rate. Assume constant volume at any brine concentration, the concentration of brine in container after 1 hour in lb/gal of salt is

137

An aqueous solution of ethyl acetate is to be saponified with NaOH. The initial concentration of the ethyl acetate is 5 g/L and that of the caustic soda is 0.10M. Values of the second order rate constant in L/gmole-min are k = 23.5 at 0 degC; k = 92.4 at 20 degC. The reaction is essentially irreversible. The time required to saponify 95% of the water at 40 deg C is At 500K the rate of bimolecular reaction is 10 times the rate at 400K. Find E in cal, the activation energy for this reaction from Arrhenius Law. The reaction A+2B--->R is 1st order with respect to each reactant. If equimolar amounts of A and B are introduced into a constantvolume reactor and (1/m) th of A remains after t1, how much will remain after t2=2t1? When the 1st order homogeneous reaction (gas-phase) A--->2.5R is carried out in an isothermal batch reactor at 2 atm with 20% inerts present, the volume increases by 60% in 20 min. When the reaction is carried out in a constant volume reactor, the time required for the pressure to reach 8 atm if the initial pressure is 5 atm, 2 atm of which consist of inerts in min is When the ID of the pipe through which a fluid flows is doubled, the pressure loss due to friction per unit length of pipe and for the same volumetric flow rate is changed by approximately a factor of When two centrifugal pumps are connected in series, the discharge changes by a factor of When two reciprocating pumps are connected in parallel, the volumetric capacity of the system changes by a factor of The pressure drop in a pipeline changes by a factor of _____ when the velocity of the flowing fluid is doubled. Cavitation occurs in a centrifugal pump when

138 139

140

141 142 143 144 145

10.3

8150 Cao/2m

43.1

1/8 1/2 1/2 1/2 the discharge pressure becomes too high

146 147 148

149

150 151 152 153 154 155 156 157

158 159 160 161 162

Oil with a viscosity of 30 cP and a density of 60 lb/cu.ft. flows through a 1/2-inch inside diameter pipe. Determine the velocity in fps below which flow will be laminar. Water at 60 deg F flows through a 3-inch inside diameter smooth horizontal pipe. If the Reynold's number is 353000, calculate the ratio of maximum velocity to average velocity. The pressure after the pump in a 6-inch inside diameter smooth pipe conducting water is 20 psia. The water is discharged at an open tank 100 ft from the pump. Calculate the rate of discharge of water in cu.ft/s. A water storage tank assumes the supply of water into a factory. Water is supplied to the tank through a booster pump installed in the water line. The theoretical pump horsepower required is 3.25 hp. What is the monthly operating cost of the pump if electric power cost on the average is PhP 3.73/kWh. The pump is 65% efficient and operates for 12 hr a day. When the impeller speed of an ideal centrifugal pump is doubled, the vol. flow rate of discharge is increased by a factor of The differential height between two points which a fluid has to be transferred is the The resistance of a layer of fluid to flow over the next layer is measured by An axial flow pump operating at a speed of 880 rpm can supply water at a rate of 3000 gpm. The maximum head that this pump can deliver in ft. of water is Specify the type of open impeller pump to use if the capacity is 400 gpm at a head of 200 ft of water. What will be the rated capacity [gpm] of a 4-1/2 inch impeller centrifugal pump operating at a speed of 3450 rpm capable of generating a head of 40 ft of water. If the speed of a centrifugal pump is doubled, the energy requirement becomes approximately ___ times the original energy requirement. A cylindrical tank 1 ft in diameter discharges through a nozzle connected to the base. Find the time needed for the water level in the tank to drop from 4 ft to 2 ft above the nozzle. The diameter of the nozzle is 1 inch and its discharge coefficient maybe taken as unity. The NPSH of a single suction centrifugal hot water pump at a speed of 3550 rpm operating at a pressure of 600 psi and a capacity of 450 gpm is ___ ft. The rate of evaporation at a given operating temperature in a n evaporator is more when

0.63 1.05 0.6

PhP 3300

1/2 potential head viscosity 20 3x2x8.5E 95 2 32

15 when the operating pressure is high capacity

An optimim number of the effects for a given application is a function of the A popular type of heat exchanger for cooling large quantities of fluid double-pipe is the An evaporator is used to concentrate 10,000 lb/hr of a 20% solution 0.82 of NaOH in water at 140 oF using saturated steam at 25 psia at a rate of 7,000 lb/hr. The OHTC is 275 BTU/hr-ft 2-oF when the pressure in the vapor is 1.7 psia. The steam economy, SE, is

163

164

A cross flow heat exchanger uses mixed air at 4 kg/s that enters at 22.2 m2 15oC and leaves at 45 oC. The air cools unmixed water, which enters at 95 oC and 0.70 kg/s. The OHTC equals 150 W/m 2-oC. After several months of operation, a scale resistance of 0.002 m 2o C/W developed. 16. The heat transfer area required to accomplish the change is As solution of 28% wt Na 2SO4 is to be crystallized to yield Glauber 285.3 salt in a four section (one section is 10 ft in length) Swenson Walker Crystallizer. It is fed to the unit at 120 oF and cooled to 60 oF using cooling water which enters at 50 oF and leaves at 70 oF. The crystallizer has a cooling surface of 3 ft 2 per foot of length. The feed rate is 500 lb/hr and the crystallizer is seeded with 50 lb/hr of 65 mesh crystals. 19. The amount of the crystalline crop (C) produced in lb per hour is

165

An insulator should have

166

Fouling factor

low thermal conductivity is a dimensionless quantity

167

Natural convection is characterized by

Reynolds number

168

The Graetz number is concerned with

169

Dropwise condensation occurs on

170

Dietus-Boelter equation for determination of heat transfer coefficient is valid

mass transfer between a gas and a liquid clean and dirt free surfaces for liquid metals

171

A type of pneumatic conveyor system characterized by a material fluidizing moving in an air stream or pressure less than ambient. If the total percentage of particles larger than the screen opening in 0.98 the feed, oversize, undersize are 36%, 89% and 3%, respectively, the effectiveness of the screen if the undersize is the product is

172

173

The estimated width of an apron conveyor having a capacity of 75 tons/hr at a speed of 50 ft/min is It is defined as the ratio of the average diameter of the feed to the average diameter of the product. The sphericity of cubical particles is The separation of a dilute slurry or suspension by gravity settling into a clear fluid and a slurry or suspension by gravity settling into a clear fluid and a slurry of higher solids content is called An ultracentrifuge is used to separate high-molecular weight fractions in polymeric or biological systems. What is the gradient for mass transfer in the separation using this mass transfer device?

305 mm

178 179

Ordinary diffusion takes place because of ___ driving force. What are the two limiting cases of steady-state diffusion?

temperature UMD and EMD

180

Which of the following is not true in (binary) equimolar counterdiffusion?

DAB = DBA

174 175 176 177

settling ratio 1 thickening temperature

181

Knudsen region

184

A fluid is flowing on a surface, which contains a component that leaches out to the fluid. Assuming that all the 3 regions of mass transfer are present, in which of these regions is diffusion controlling? In unsteady-state mass transfer, the quantity (D ABt/rm^2) is referred to as What is the equivalent of Prandtl number in convective mass transfer? If kx > ky, then the controlling phase is

185

In two-phase mass transfer, equilibrium may exist

at the interface

186

Which of the following processes may always be regarded as a constant- humidity process? Air conditioning in tropical countries involves

cooling of air

182 183

187

188 189 190 191 192

193

194

unaccomplished change Sc the liquid phase

humidification by a process similar to that in a cooling tower What do you call the steady-state non-equilibrium temperature dry-bulb reached when a small amount of water is contacted under adiabatic temperature conditions by a continuous stream of gas? The moisture content of a solid is given as 50% wet basis. What is 0.5 the moisture content, dry basis? The moisture that can be removed by drying is called equilibrium moisture Falling-period in drying terminates at the end of constantrate period Which is not true at the interphase of a gas scrubbing operation? the solute concentration of the gas is less than that of the bulk He and N2 gas are contained in a conduit 5 mm in diameter and a 2.35 exp -5 0.1 m long at 298 K and a uniform pressure of He at one end of the tube is 0.6 atm and 0.02 atm at the other end. Assuming equimolar countercurrent diffusion, the flux in kmol/s-m 2 is 5280 100 m3/hr of air at 60°C and 20% RH is needed for a chemical reactor. This will be obtained from process air at 60 °C and 10% RH by humidifying adiabatically the process air followed by heating to its original temperature. The wattage of the heater at 80% efficiency is

195

Wet solid is to be dried from 36% to 8% moisture in 5 hr under 1 hr constant drying condition. Critical and equilibrium moisture contents are 14 and 4% respectively. Calculate how much longer will it take to dry the same material from 8% to 5.5% moisture under constant drying condition. All moisture contents are on a dry basis.

196 197

The unit of volumetric diffusivity is If reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. the reflux ratio is Which of the following pr ovides maximum contact surface for a liquid-vapour system?

198

cm^2/sec 0.5 packed lower

199 200 201 202 203 204

205

In extraction, as the temperature increases, the area of heterogeneity (area covered by bimodal curve) The suitable evaporator for concentration of foaming liquids is Macroscopic transfer of mass between moving fluid and surface which is of different concentration is called For a packed column the main purpose of packing is to

decreases long tube evaporator molecular diffusion strengthen the column

In a gas absorption operation, when the operating line crosses the the NTU is zero equilibrium curve Methanol diffuses in 0.15 cm stagnant film of 1:1 mole mixture of 0.15 hydrogen and CO2 at 100oC and 2 atm. The partial pressures of methanol on both sides are 0.6 and 0.2 atm. The average diffusivity of methanol in the hydrogen and CO 2 at 0 oC and 1 atm in cm 2/s is 0.92

208

Gaseous reactant A decomposes according to the reaction A --> 3R (-rA = 0.5 CA mole/L-min). The feed, which consists of 70% A and 30% inert, enters a 1.5-m 3 CSTR at a flow rate of 150 L/min. 4. If CA0 = 0.30 mole/L, what is the conversion, XA? Between 0 degC and 50 degC, the average activation energy of a certain reaction is 80 kJ/mol. How many times faster will the reaction occur at 300 K than at 275 K? Consider a gas-phase reaction 2A ---> R + 2S with unknown kinetics. A space velocity of 0.8/min is needed for 95% conversion of A in a PFR. Find the mean residence time or holding time of the fluid in the PFR. For Newtonian fluids, the shear stress is

209

An ideal fluid is one that is

compressible

210

Water flows through an 8-in (ID=7.981 in) steel pipe at an average velocity of 6 ft/s. Downstream the pipe splits into an 8-in main and a 2 in (ID=2.067 in) bypass pipes. If the velocity in the bypass is twice the velocity of the main pipe, the volumetric flow rate [ft 3/s] in the main pipe is An imaginary line within a fluid flow such that a tangent at any point indicates the direction of flow at that point. Air at 250C [viscosity=0.018 cP] enters a section of 2-in schedule 40 commercial steel pipe at a gauge pressure of 310 kPa and a flow rate of 1200 kg/h. Assuming isothermal flow, what is the pressure drop [kPa] in 60 m of pipe? A simple pitot tube measures

10.58

pitot tube

215

Which of the following meters will have the highest permanent pressure loss? In the flow meter equation, Y, indicates the

216 217

The loss due to sudden contraction is proportional to Stoke’s law is valid when the particle Reynolds number is

velocity