NO QUESTION A B1 A valve that controls flow by means of a disk or wedge-shaped dam sliding at right angles to the direction of flow and seating tightly in the valve body is a gate valve butterfly valve 2 The friction factor for flow through a pipe with relative roughness of 0.004 at a Reynold's No. of 80,000 is approximately equal to 0.052 0.025 3 The equation that relates friction factor and Reynold's No., f=64/Reynold's No. holds for smooth pipes laminar and turbulent flow 4 Oil flows under laminar conditions inside a steam heated copper pipe. The overall heat transfer coefficient is approximately equal to the heat transfer coefficient of the oil 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 co- currently 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 evaporation stripping 7 The maximum number of plates for a given distillation system is obtained at variable reflux maximum reflux 8 The correct unit for the specific rate constant for the reaction A--- >B determined to be first order is square liter/square mol/min square liter/square mol/square min 9 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 large effect little effect 10 For a cylinder where steady-state radial heat transfer takes place the heat flux is constant maximum heat transfer rate occurs at the surface 11 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 separation plate theoretical plate 12 Crystallization occurs in a solution that is concentrated unsaturated 13 Mass transfer in a flowing fluid may be correlated by Sherwood, Nusselt and Reynold's No Peclet, Reynold's and Schimdt No 14 The ratio of the average diameter of the feed to the average diameter of the product is the settling ratio discharge ratio 15 The rate of formation of C for the reaction 2A + B ---> C is found to be rate=k(A)(B) the rate of formation of C is equal to the rate of disappearance of B the order of reactio is zero 16 A device for increasing the velocity of a fluid in steady flow is a nozzle vent 17 In steady-state backmix flow reactor, composition is not constant throughout the reactor constant throughout the reactor 18 The amount of money obtainable from the sale of used property over and above any changers involved in removal and sale is called net value salvage value 19 In fractionation, an increase in reflux ratio increases the number of theoretical plates decreases the reboiler duty 20 In mass transfer where the solute in the gas phase is very soluble in the liquid phase the ratio of liquid phase resistance to the overall resistance is close to unity the gas phase resistance is approximately equal to the total resistance 21 Heat transfer in turbulent flow may be described through an empirical equation correlating Nusselt, Stanton and Reynold's Nos Nusselt, Prandtl and Reynold's Nos 22 Which of the following fittings exhibits the highest pressure drop for the same flow conditions? 90-degree long radius elbow 90-degree standard elbow 23 A chamber into which steam from a high pressure line can be bled during periods of low steam demand from the power plant is called switching bank vent 24 Which one of the following pipes has the highest relative roughness? 2" diameter Wrought iron pipe 4" dia Wrought iron pipe 25 In steady-state heat transfer through a series of materials with varying resistances, the heat transfer rate decreases towards the direction of heat transfer varies with the thermal conductivity of each material 26 Reactions whereby reactants proceed along several paths and give different products are polymeric reactions reversible reactions 27 Which one among the following materials has the best insulating property? window glass wood 28 An operation where warm vapor mixture is cooled such as by contact with a liquid resulting in condensation and decreased humidity is evaporation dehumidification 29 The pressure exerted on a plane parallel to the direction of flow of a moving fluid is called gauge pressure velocity pressure 30 For mass transfer to take place, there must be a phase change reaction component 31 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 212 deg F 80 deg F 32 The diffusity of water in air at 100 deg F in sq.cm./sec is 0.256 0.278 33 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 5.9 2.5 34 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 66.6 58.1 35 When 32 kg of methane is burned completely the theoretical oxygen required is 16 kg 64 kg 36 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 32.2 31.4 37 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 4 2.18 38 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 over 100,000 but less than a million over 100 but less than 200 39 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 0.0378 0.0504 40 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 4440000 5130000 41 This is a steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapor-gas mixture. wet-bulb temperature dew point 42 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 74.3 75 43 In adiabatic humidification, it is possible to maintain the temperature of water constant since according to the phase rule, the degrees of freedom is 3 the system can be well insulated from the surroundings 44 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 0.1 0.05 45 The portion of water in the wet solid that cannot be removed by the air in its contact is called free moisture final moisture content 46 This type of drier is used for drying pasty materials such as wet filter cakes and lumpy solids rotary drier flash drier 47 In the constant-rate period, the rate of drying is established by 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 48 Unbound moisture in granular and porous solid moves through the intertices of the solid by a mechanism involving desorption surface tension 49 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 0.542 hrs 1.846 hrs 50 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 0.12 0.034 51 In drying at the falling rate period, the rate at which moisture is removed from the solid material remains constant increases with time 52 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 to reduce the solid to the smallest size feasible 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 0.3 0.8 54 Tung meal containing 55% oil is to be extracted at the rate of 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 3 4 55 The movement of molecules over a substantial distance is associated with the transfer of heat by convection conduction 56 The mode of heat transfer that can take place in a vacuum is known as convection conduction 57 The overall conductance for a composite material in series is equal to the sum of the individual conductances sum of the individual conductivities 58 Film and drop are terms associated with boiling condensation 59 A 6-in Sch 80 steel pipe is carrying glycerin at an average 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. 99.95 415.7 60 An oak (k=0.096 Btu/h-ft-degF) door, 30 in wide, 78 in high, and 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. 97 242 61 Determine the length needed for a simple concentric-tube, 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. 185.5 m 11.02 m 62 A saturated solution containing 1500 kg of potassium chloride at 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. 4301 kg 1500 kg 63 An evaporator, working at atmospheric pressure, is to 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. 55.8 sq.m. 58.5 sq.m. 64 2.5 kg/s of a solution at 288K containing 10% dissolved solids is 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. 115 kPa 101.3 kPa 65 An acetone-air mixture containing 0.015 mol fraction of acetone 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? 10.92 9.12 66 A still has a liquor composition of ortho-xylen 10%, meta-xylene 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. 37 38 67 A mixture of alcohol and water with 0.45 mol fraction of alcohol 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? 10 9 68 Prepared cottonseed meats containing 35% extractable oil are 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? 72.2 28.7 69 0.4 kg/s of dry seashore sand, containing 1% by weight of salt, 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? 0.492 0.429 70 Forty-five pounds per minute of water is heated from 60 to 180 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 hо of 1000 Btu/hr-sq.ft.-degF, calculate the inside heat transfer coefficient [Btu/hr-cu.ft-degF]. 2173 696 71 How many cu.ft. per minute of entering air is needed to 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. 12.54 12.68 72 Nicotine is to be extracted from water using kerosene. If 100 lb 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]} 64.5 54.6 73 We must cool 2500 gpm of water from 120 to 80 deg F. A 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. 77.2 150 74 We wish to build an economical cold room 20 ft square and 10 ft 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? 3537 8457 75 A colloidal solution is to be concentrated from 15 to 65% solids. 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]? 10500 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. 38.1 18.3 77 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. 2951 1644 78 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. 2.21 1.35 79 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. 63 84 80 Determine the net positive suction head available to a centrifugal 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] 34.2 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]? 11.61 14.24 82 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? 113 227 83 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? 0.15 0.5 84 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 [B]=0.4(1-x )/(1- 0.5x ) [B]=0.4(1-x )/(1- 1.5x ) 85 Heat is generated in a 2.5 cm square copper rod at the rate of 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. 75.2 55.2 86 A 5cm diameter cylinder is maintained at a constant temperature 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/m-degC). 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]. 13 272 87 A building wall consists of a 6-in of concrete (kc= 0.7 Btu/hr-ft- 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]. 0.028 0.119 88 Current is passed through a cylindrical laboratory heater, which 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]. 325 300 89 A straight rectangular fin has a length of 3.5 cm, a thickness of 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. 1500 W 4392 W 90 A gaseous fuel is composed of 20% methane( CH4), 40% 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. 1 18 91 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]. 170 100 92 Two rooms A and B of identical volume are connected by an open doorway. The thermostat in the rooms are set so that Ta<Tb. Which room contains more air molecules? A B 93 If the absolute temperature of a gas is doubled, the mean speed of the gas molecules is doubled. increases 4 times 94 When ice cubes melt in a glass of water, the temperature of the resulting mixture of water and ice increases. decreases. 95 In all naturally occurring processes, the entropy of the universe increases. decreases. 96 An inventor seeking a patent claims that a building may be comfortably heated in winter by a device that draws heat into the building from the earth, even though the temperature of the earth is lower than the desired temperature inside the building. He further claims that the quantity of heat supplied to the building in a given time period can significantly exceed the work done by the device during the same period. If you were a patent clerk (like the young Albert Einstein), what should be your recommendation about the application? The application should be rejected because it violates the first law of Thermodynami cs. The application should be rejected because it violates the second law of Thermodynamic s. 97 A fixture containing an ordinary incandescent light bulb is connected to a dimmer switch. The dimmer is adjusted so that the temperature of the tungsten filament inside the bulb increases from 1300K to 2600K. The total power radiated by the bulb doubles. quadruples. 98 A 30 MW geothermal electric power plant uses hot steam from the earth at 157 deg C to heat and vaporize isobutane, which turns a turbine that is connected to a generator. The isobutane is subsequently cooled to 27 degC using fans and condensed back to a liquid. The overall efficiency of the plant is 40% of the ideal (Carnot) efficiency. How many joules of heat must be released to the atmosphere per second? 2.5 e8 2.2 e8 99 The material which remains unchanged in a process is limiting reactant tie substance 100 The ratio of the total quantity of a reactant present in the reactor feed of a recycling operation to the quantity of the same reactant entering the operation as fresh feed is the recycle ratio combined feed ratio 101 The heating value measured when water formed from combustion is in the liquid state. Gross Calorific Value Heat of combustion 102 In the combustion of solid fuels, the tie element between the feed and the refuse is the cooked coal ash 103 The coal analysis which is based upon the volatilization characteristics of the fuel is Proximate analysis Modified analysis 104 An Orsat analysis of the flue gas when pyrite is roasted is on a SO2-free basis SO3-free basis 105 The empirical relation which allows one to compute for the net hydrogen in a given solid fuel is the Calderwood equation Theoretical Oxygen Equation 106 The equivalent of 45degTw in the Baume scale is 26.63 28.32 107 A furnace completely burns coal containing 70%C. Analysis of the flue gas shows 15% CO2, 4% O2, 81% N2, and no CO. What is the % of the net hydrogen in the coal? 1.2 1.53 108 Which has the lowest water content? dew point at 20degC 70% RH 109 A contract was made between a buyer and a paper manufacturer for paper containing 5% moisture at PhP450/tonne FOB on specifications that price adjustment will be made if the quality is different. How much should the buyer pay for 1 tonne of paper with 8% moisture content? Freiht cost is PhP45/tonne. PhP 405 PhP 424.26 110 One drier will dry a material from 45% moisture (wb) to 20% moisture (db). From here the material enters another drier where the water content is further reduced to give a final product weighing 1000 kg. If the total evporation from both driers is 800 kg, the moisture of the final product is 0.01 0.02 111 An experimental oil is used to distill 6000 kg.hr of Athabasta tar sand which analyzes 30% 'heavy oil', 'light oil', and non-volatile matter. If the distillate contains 12 % heavy oil and this constitutes 25% recovery of the component, the weight in kg of the distillate obtained is 2250 3750 112 Coal fired in a furnace has a heating value of 13800 Btu/lb and contains 78.05%C and 1.2%S. The proximate analysis shows 4%M, 24%FC, 8%A and the analysis of the refuse shows 8%VCM, 25%FC and 32% ash. Calculate the % of C lost in the refuse. 4.22 8 113 Ninety grams of ethane and 384 grams of oxygen are fed continuously to a laboratory furnace. The total combustion products collected was 16.2 gmole with no carbon dioxide. However, not all of the ethane was burned due to faulty combustion. The fraction of ethane that was burned is equal to 0.8 0.85 114 The furnace at the Bataan refinery is using a fuel gas which contains methane, ethane and 20% nitrogen. The orsat analysis of the combustion products showed 7.8% CO2, 7.4% O2, and 84.8% N2. The gas is burned with excess air. The % methane in the fuel gas is 63.25 57.24 115 Pyrite containing 78% FeS2 and 22% gangue is burned with excess air to produce a stack gas with the following analysis: 7.29% SO2, 8.92%O2, 82.44%N2 and 1.35%SO3. If the cinder was found to have a partial analysis of 62.10% Fe2O3, the % of FeS2 lost in the pyrite is 3.52 6.53 116 The unit of k for a 1st order elementary reaction is 1/time conc/time 117 If the temperature of a chemical reaction is raised by 10 degC, the rate of reaction is increased by a factor of 4 3 118 The E of a reaction may be lowered by increasing temperature decreasing temperature 119 The mechanism of a reaction can sometimes be deduced from the activation energy the temperature dependency of the rate 120 The equilibrium constant in a reversible chemical reaction at a given temperature depends on the initial conc of the reactants depends on the conc of one of the products at equilibrium 121 If the volume of a reaction vessel is suddenly reduced to one half its original volume the rate will increase by a factor of 2 4 122 The rate of reaction is not influenced by conc of the reactants molecularity of the reaction 123 The net rate of reaction of an intermediate is 0 2 124 A reaction is known to be first order in A. A straight line will be obtained by plotting log Ca vs time Ca vs time 125 If the reaction 2A ---> B+C is second order, which of the following plots will give a straight line? 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 -ra = k Ca^2 Cb^4 -ra = k Ca Cb^2 127 It states that the rate of a chemical reaction is proportional to the activity of the reactants. Le Chatelier's principle Hess' Law 128 The half life of a material undergoing second order decay is proportional to the square of the initial conc independent of initial conc 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. 66.8 74.7 130 A first order reaction has a specific rate constant of 3e-3 per sec. The half life is 0.0021 s 100 s 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 45.1 min 19.6 min 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 3.83 7.43 133 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. 25.36 m 32.5 m 134 The set of data given below is for the parallel reaction: a---k1-- >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 0.1697 0.183 135 A batch reaction 2D+E----->F has a conversion factor expressed 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 257 275 136 A container holds 100 gal of salt solution containing 50 lb of 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 0.732 0.427 137 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 10.3 11.4 138 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. 8150 9150 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? Cao/2m Cao/(2m-1) 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 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 1/8 1/16 142 When two centrifugal pumps are connected in series, the discharge changes by a factor of 1/2 1 143 When two reciprocating pumps are connected in parallel, the volumetric capacity of the system changes by a factor of 1/2 1 144 The pressure drop in a pipeline changes by a factor of _____ when the velocity of the flowing fluid is doubled. 1/2 1 145 Cavitation occurs in a centrifugal pump when the discharge pressure becomes too high the discharge valve is closed 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. 0.63 13.1 147 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. 1.05 1.22 148 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. 0.6 3.58 149 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. PhP 3300 PhP 5000 150 When the impeller speed of an ideal centrifugal pump is doubled, the vol. flow rate of discharge is increased by a factor of 1/2 1 151 The differential height between two points which a fluid has to be transferred is the potential head pressure head 152 The resistance of a layer of fluid to flow over the next layer is measured by viscosity friction factor 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 20 36 154 Specify the type of open impeller pump to use if the capacity is 400 gpm at a head of 200 ft of water. 3x2x8.5E 4x3x8.5E 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. 95 134 156 If the speed of a centrifugal pump is doubled, the energy requirement becomes approximately ___ times the original energy requirement. 2 4 157 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. 32 55 158 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. 15 20 159 The rate of evaporation at a given operating temperature in a n evaporator is more when when the operating pressure is high the operating pressure is low 160 An optimim number of the effects for a given application is a function of the capacity economy 161 A popular type of heat exchanger for cooling large quantities of fluid is the double-pipe plate 162 An evaporator is used to concentrate 10,000 lb/hr of a 20% solution of NaOH in water at 140 o F using saturated steam at 25 psia at a rate of 7,000 lb/hr. The OHTC is 275 BTU/hr-ft 2 - o F when the pressure in the vapor is 1.7 psia. The steam economy, SE, is 0.82 0.863 163 A cross flow heat exchanger uses mixed air at 4 kg/s that enters at 15 o C and leaves at 45 o C. The air cools unmixed water, which enters at 95 o C and 0.70 kg/s. The OHTC equals 150 W/m 2 - o C. After several months of operation, a scale resistance of 0.002 m 2 - o C/W developed. 16. The heat transfer area required to accomplish the change is 22.2 m 2 25 m 2 164 As solution of 28% wt Na 2 SO 4 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 o F and cooled to 60 o F using cooling water which enters at 50 o F and leaves at 70 o F. 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 285.3 249.3 165 An insulator should have low thermal conductivity high thermal conductivity 166 Fouling factor is a dimensionless quantity does not provide a safety factor for design 167 Natural convection is characterized by Reynolds number Grashhoff number 168 The Graetz number is concerned with mass transfer between a gas and a liquid absorption with chemical reaction 169 Dropwise condensation occurs on clean and dirt free surfaces smooth clean surfaces 170 Dietus-Boelter equation for determination of heat transfer co- efficient 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 opening in the feed, oversize, undersize are 36%, 89% and 3%, respectively, the effectiveness of the screen if the undersize is the product is 0.98 0.89 173 The estimated width of an apron conveyor having a capacity of 75 tons/hr at a speed of 50 ft/min is 305 mm 610 mm 174 It is defined as the ratio of the average diameter of the feed to the average diameter of the product. settling ratio screen-mesh no 175 The sphericity of cubical particles is 1 0.87 176 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 thickening 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? temperature pressure 178 Ordinary diffusion takes place because of ___ driving force. temperature pressure 179 What are the two limiting cases of steady-state diffusion? UMD and EMD ordinary and Knudsen 180 Which of the following is not true in (binary) equimolar counter- diffusion? D AB = D BA c = c A + c B 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? Knudsen region turbulent region 182 In unsteady-state mass transfer, the quantity (D AB t/r m^ 2 ) is referred to as unaccomplishe d change relative resistance 183 What is the equivalent of Prandtl number in convective mass transfer? Sc Sh 184 If k x > k y , then the controlling phase is 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? dry-bulb temperature wet-bulb temperature 189 The moisture content of a solid is given as 50% wet basis. What is the moisture content, dry basis? 0.5 1 190 The moisture that can be removed by drying is called equilibrium moisture bound moisture 191 Falling-period in drying terminates at the end of constant- rate period origin of R vs X plot 192 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 the solute concentration of the liquid is less than that of the bulk 193 He and N 2 gas are contained in a conduit 5 mm in diameter and 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 2.35 exp -5 2.44exp -5 194 100 m 3 /hr of air at 60C and 20% RH is needed for a chemical reactor. This will be obtained from process air at 60C 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 5280 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. 1 hr 1.6 hr 196 The unit of volumetric diffusivity is cm^ 2 /sec cm/sec 197 If reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. the reflux ratio is 0.5 2 198 Which of the following provides maximum contact surface for a liquid-vapour system? packed lower bubble-cup plate column 199 In extraction, as the temperature increases, the area of heterogeneity (area covered by bimodal curve) decreases increases 200 The suitable evaporator for concentration of foaming liquids is long tube evaporator short tube evaporator 201 Macroscopic transfer of mass between moving fluid and surface which is of different concentration is called molecular diffusion unsteady-state diffusion 202 For a packed column the main purpose of packing is to strengthen the column increase the 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 CO 2 at 100 o C 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 o C and 1 atm in cm 2 /s is 0.15 0.31 205 Gaseous reactant A decomposes according to the reaction A --> 3R (-r A = 0.5 C A 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? 0.92 0.86 206 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? 14.7 18.5 207 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. 0.54 min 0.85 min 208 For Newtonian fluids, the shear stress is constant. inversely proportional to rate of deformation. 209 An ideal fluid is one that is compressible incompressible & viscous 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 10.58 5.29 211 An imaginary line within a fluid flow such that a tangent at any point indicates the direction of flow at that point. stream tube velocity profile 212 Air at 25 0 C [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? 350 155 213 A simple pitot tube measures acoustical velocity superficial velocity 214 Which of the following meters will have the highest permanent pressure loss? pitot tube orifice 215 In the flow meter equation, Y, indicates the mass flow rate compressibility factor 216 The loss due to sudden contraction is proportional to velocity turbulence 217 Stoke’s law is valid when the particle Reynolds number is < 1 > 1 218 Priming needed in a Reciprocating pump Gear pump 219 Maximum theoretical suction lift for water at 60˚F by a centrifugal pump is 34 ft. The same for water at 200˚F will be 40 ft 37 ft 220 The most economical valve for use with large diameter pipes. butterfly globe 221 Multistage compressors are used in industry because, they reduce the cost of compressor reduce the size requirement 222 For ideally incompressible fluid, the mach number will be 0 1 223 of the following produces maximum pressure difference for transportation of gases? vacuum pumps blowers 224 The fluid property which matters for falling rain drops to acquire spherical shape is its pressure height of descend 225 A wastewater solution having a volume of 1000 L contains 0.21 kg phenol/m 3 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? 0.007 kg 0.106 kg 226 The overhead product composition decreases with time in batch distillation with reflux continuous distillation with reflux 227 For a binary mixture with low relativity, continuous rectification to get pure products will require low reflux ratio small cross- section 228 Chemisorption is the same as van der Waals characterized by adsorption of heat 229 The stage efficiency in leaching depends on the time of contact between the solid and the solution rate of diffusion of the solute through the solid and into the liquid 230 Weeping in distillation or absorption column increases tray efficiency provides larger surface for mass transfer 231 What are the two contacting phase in leaching? extract phase and raffinate phase solvent phase and solute phase 232 Hydrogen sulfide is removed from water by contacting the solution with warm air. The operation is Distillation Leaching 233 Disregarding the cost, which is the best solvent for the extraction of acetic acid from an aqueous solution at 25deg C? caproic acid chloroform 234 Professional Regulations Commission was created under P.D. No. 223 P.D. No. 233 235 A chemical engineer who designed and built a new type pf reactor and for three years, sold many units to the public can still patent his reactor. TRUE FALSE 236 A person who has passed the Chemical Licensure Examination can take his/her oath as a chemical engineer if his/her age is not less than _______ years. 18 19 237 Which of the following is not a requirement for utility model registration? inventive step novelty 238 A section of the patent application containing detailed descriptions of the benefits obtained from using the invention is called the disclosure abstract 239 A document issued by the DENR secretary indicating that the proposed project will cause significant negative environmental impact. Environmental Impact Statement Environmental Compliance Certificate 240 In the Philippines, sulfur for sulfuric acid manufacturing is sourced from _______ industry. paper cement 241 Sulfur is undesirable in petroleum because 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. fillers brighteners 243 Polyethylene is an example of _____________ polymerization condensation addition 244 Principal chemical conversion in the production of resin from monomer. condensation hydration 245 Carbon black is added to rubber compounding as activator curing agent 246 The binder for all the powder materials of paint pigment vehicle 247 A fibrous material left after cane sugar has been milled is commonly called as bagasse pulp 248 Molasses is a by product of raw sugar from the ______ process milling extraction 249 Kraft process is a common name for sulfate pulping sulfite pulping 250 Water insoluble cell binders of wood pulp cellulose 251 DDT means Diphenyldichlor otriphenylethan e dichlorodiphenyl dichloroethane 252 Rancidity of oil can be reduced by decoloration hydrogenation 253 Varnish does not contain pigment dryer 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 extrusion mastication 257 Alkyl benzene sulfonate (ABS) is a detergent rubber 258 Neoprene is a monomer synthetic rubber 259 Steam enters an adiabatic turbine at 10 MPa and 500 deg C 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. 0.2348 0.3216 260 Work is a property of the system path function 261 Throttling process is a reversible and isothermal process an irreversible and constant entropy 262 A sample consisting of 1.00 mole of Argon gas is expanded isothermally and reversibly at 0C from 22.4L to 44.8L. The heat absorbed by the system is 0 +1.13 kJ 263 Maximum work can be obtained from a system when the change taking place in it is isothermal adiabatic 264 The ratio of work performed by a system and the heat it absorbed from a reservoir is referred to Entropy Gibb’s free energy 265 According to the first law of thermodynamics Energy is neither lost nor gained in any energy transformation. Perpetual motion is possible. 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 greater than 0.85 in between 0.75 and 0.85 267 In choosing the refrigerant, the fluid must have the following characteristics, except environmentally benign has a vapor pressure less than atmospheric 268 Coolers and boilers are ordinarily operated at ________ condition. isobaric isenthalpic 269 For an isolated system, maximum entropy will occur at half-life critical condition 270 A carnot cycle consists of two isothermal and two adiabatic process two isochoric and two adiabatic process 271 This is also known as the volume fraction of the voids in packed beds. sphericity porosity 272 A measure of the ratio of the drag force acting on a unit area of the impeller & the inertial stress. Froude number Reynold’s number 273 Sulfuric acid is pumped at 3 kg/s through a 60-m length of 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. 3 2 274 The equation del(P) = -(rho)(g) del(z) is known as the hydrostatic vertical law for which all the following assumptions are applied, except shear forces are not involved fluid is incompressible 275 Which of the following can be adjusted by human operator in a closed feedback control loop? set point controller output 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. current temperature 277 Dead time is a function of distance and momentum acceleration 278 A pneumatic controller is used to control temperature within the 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? 2.83kPa/K 0.35kPa/K 279 The parameter which completely describes the behavior of the response to a disturbance of a second order system is the Time constant damping coefficient 280 Water is flowing through a 3-inch schedule 40 pipe at 60 deg F. 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? 11.61 ft/s 37.1 kg/s 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 9365 9461 282 The equivalent diameter of a concentric annular space where 1- inch OD pipe is located inside a 2-inch ID pipe is pi/4 inch 1 inch 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%. 20.2 41.4 284 The BPR of a 50% NaOH solution at an evaporator pressure of 4.7 psia is 73 degF 173 degF C D ANSWER SCORE globe valve orifice a 1 0.03 0.038 0 turbulent flow only laminar flow only 0 equal to the heat transfer coefficient equivalent to the resistance offerred by the pipe equal to the heat transfer coefficient of the steam d 1 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. b 1 rectification fractionation c 1 minimum reflux optimum reflux c 1 mol/liter/min liter/mol/min 0 no effect significant effect 0 the heat transfer is constant the temperature is uniform throughout the cylinder 0 transition plate bubble plate 0 supersaturated saturated c 1 Sherwood, Reynold's and Schimdt No Prandtl, Schimdt and Reynold's No 0 reduction ratio classification ratio c 1 the value of k is independent of the initial concentrations of A and B the reaction cannot proceed 0 orifice venturi a 1 a function of time not uniform throughout the reactor and varies from time to time 0 book value market value b 1 increases the amount of distillate increases the condenser duty 0 the gas phase resistance is negligible the ratio of gas phase resistance to liquid resistance is approximately zero 0 Peclet, Stanton and Prandtl Nos Schimdt, Peclet and Friction Nos 0 45-degree standard elbow square-corner elbow 0 compressor accumulator b 1 1" dia Drawn tubing 4" dia Riveted steel pipe 0 through each material is inversely proportional to the thickness of the material is constant throughout the series of materials 0 parallel reactions consecutive reactions c 1 air concret b 1 humidification extraction b 1 tangential pressure static pressure b 1 concentration gradient momentum gradient c 1 113 deg F 146 deg F c 1 1.484 0.581 b 1 1.5 0.6 0 33.4 54.4 0 128 kg 32 kg c 1 26.4 57.8 0 1.5 2.75 0 over 20 million over 2 but less than 3 0 0.0454 0.0252 0 6930000 2040000 0 saturation temperature dry-bulb temperature 0 75.26 78.5 0 the temperature of the air can also be maintained constant increase in the humidity of the air is insignificant 0 0.02 0.01 0 equilibrium moisture content critical moisture content c 1 tray drier freeze drier c 1 air flow perpendicular to the surface of the solid air flow parallel to the solid surface 0 surface renewal moisture diffusivity d 1 2.129 hrs 3.42 hrs 0 0.01155 0.00116 0 decreases with time no drying takes place 0 to use cross flow evaporation to use spray percolators 0 1.5 2.3 0 5 6 0 radiation all of A, B and C a 1 radiation all of A, B and C c 1 inverse of the total resistance sum of the individual resistances c 1 evaporation all of A, B and C 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 0.294 0.249 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(1- 0.5x )/(1-x ) [B]=0.2 0 25.2 20 0 3478 3750 0 0.714 6.01 0 100 25 0 13943 W 19343 W 0 23 33 0 38 0.038 0 both contain the same no of air molecules 0 increases by about 40% decreases. c 1 stays constant. c 1 stays the same. may increase or decrease. 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. 0 increases 8x. increases 16x. 0 3 e7 5.2 e8 0 excess reactant product yield b 1 reactant ratio fresh-feed conversion b 1 Latent Heat of Condensation Net Calorific Value 0 moisture volatile combustible matters 0 Ultimate analysis Elemental analysis 0 O2-free basis N2-free basis 0 Dulong's formula Oxygen unaccounted for equation 0 32.48 42.56 0 2.38 6.13 0 absolute humidity of 0.05 60% saturation 0 PhP 434.16 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 1/conc-time 0 2 1.5 0 adding a catalyst removing the products of the reaction 0 the net equation the rate law. 0 does not depend on the initial concentrations is not a characteristic of the reaction 0 8 16 0 nature of reactants temperature 0 > 0 <0 0 log Ca vs reciprocal time 1/Ca vs time 0 lof Ca vs time Ca vs time 0 -ra = k Ca -ra = k Cb^2 0 Law of Mass Action Second Law of Thermo 0 proportional to initial conc inversely proportional to initial conc 0 85.3 99.1 0 231 s 768 s 0 19.1 min 10.4 min 0 8.33 9.33 0 52.63 m 56.23 m 0 0.3394 0.6197 0 300 527 0 0.327 0.237 0 12.7 20.7 0 9550 10150 0 Cao/(1-2m) Cao/2 0 37.1 31.8 0 1/32 1/64 0 2 4 0 2 4 0 2 4 0 the suction pressure is too high suction is lost 0 16.9 87.2 0 1.72 1.89 0 21 58.3 0 PhP 7000 PhP 12000 0 2 2exp2 0 velocity head dynamic head 0 surface tension drag coefficient 0 63 85 0 4x3x6 3x2x13 0 248 320 0 8 10 0 77 94 0 25 30 0 there is a vacuum when the liquid level is high 0 efficiency none of the given choices 0 shell and tube extended surfaces 0 0.89 0.92 0 17 m 2 20 m 2 0 255.65 214.65 0 less resistance to heat flow a porous structure 0 accounts for additional resistance to heat flow none of these 0 Peclet number Prandlt number 0 heat transfer in turbulent flow heat transfer in laminar flow 0 contaminated cooling surfaces polished surfaces 0 for fluids in turbulent flow when Grashhoff number is very important 0 pressure- vacuum vacuum 0 0.76 0.65 0 1220 mm 2400 mm 0 reduction ratio average particle diameter 0 0.7 0.6 0 sorting centrifugation 0 concentration electric field 0 concentration electric field 0 thermal and ordinary thermal and Knudsen 0 J A = J B N A = -cD AB dx A /dz 0 buffer region viscous sub- layer 0 relative time relative position 0 Bi Pe 0 the interface either of the bulk phases 0 in the liquid phase in either film 0 water-cooling in a cooling tower heating of air 0 dehumidificatio n and removal of sensible heat dehumidificatio n by condensing water vapor in a refrigerator 0 adiabatic saturation temperature dew point temperature 0 2 50 0 free moisture unbound moisture 0 critical free moisture content equilibrium moisture content 0 the solute concentration of the liquid and gas phase are equal the solute concentration of the gas is greater than the liquid 0 1.77exp -6 1.22 exp -6 0 10050 11570 0 2.3 hr 2.9 hr 0 cm^ 3 /sec cm^ 2 /sec^ 2 0 50 150 0 sieve-plate column wetted wall column 0 remains unchanged 0 vacuum evaporator falling film evaporator 0 convective mass transfer all of these 0 increase the pressure drop in the tower reduce the flow rate across the column 0 the gas flow rate is maximum the number of stages is infinite 0 0.51 0.68 0 0.71 0.65 0 20.9 22.4 0 0.87 min 1.18 min 0 equal to shear rate of deformation. a linear function of the shear rate of deformation. d 1 incompressible incompressible & inviscid d 1 1.84 0.25 0 streamline none of these c 1 101.3 61 0 mean linear velocity local velocity d 1 venturi rotameter b 1 coefficient of discharge cross-sectional area 0 velocity head static head c 1 < 5 0 0 Centrifugal pump Diaphragm pump 0 34 ft 8 ft 0 needle gate 0 resemble closely to isothermal compression are easy to control 0 1.5 5 b 1 fans compressors d 1 viscosity surface tension d 1 0.189 kg 0.198 kg 0 continuous distillation without reflux distillation operating at total reflux 0 less number of trays high reflux ratio 0 an irreversible phenomenon always in equilibrium c 1 both A and B either A or B because these two mean the same thing 0 results due to low gas velocity is due to bubble cups 0 feed phase and solvent phase overflow and underflow 0 Absorption Stripping d 1 3-heptanol toluene 0 P.D. No. 232 P.D. No. 826 0 it depends not governed by law 0 21 23 0 industrial applicability a technical solution to problem 0 request claims 0 Environmental Impact Assessment Environmental Critical Project 0 petroleum detergents 0 it poisons the catalyst in the refining process all that are mentioned a 1 builders perfume c 1 copolymerizatio n natural b 1 polymerization alkylation d 1 retarders fillers a 1 opacifier filler a 1 cellulose waste c 1 evaporation crystallization c 1 bleaching calendering b 1 xylem lignin d 1 Dichlorodipheny ldichlorobutane diphenyldichlor otriphenylbutan e c 1 oxidation purification b 1 thinner anti-skinning agent a 1 increase atmospheric oxidation give elasticity and prevent cracking of the film d 1 an inorganic polymer thermosetting plastic c 1 vulcanization calendering d 1 pesticide polyester a 1 polyester pigment b 1 0.6784 0.7652 0 state function state description of a system b 1 a reversible and constant entropy process constant enthalpy process 0 +1.57 kJ +2.27 kJ 0 reversible irreversible c 1 carnot efficiency Helmholtz free energy c 1 Energy is conserved in quality but not in quantity. Energy is being created as time passes. We have more energy in the universe now than when time began. 0 less than 0.75 in between 0.84 and 0.90 0 must be economically viable exist at a high pressure at the condensation temperature 0 isothermal isentropic a 1 equilibrium start of the process c 1 one isochoric, one isobaric, and two adiabatic process one isothermal, one isochoric and two adiabatic process 0 superficial velocity specific volume 0 Mach number Power number 0 0.2 0.124 0 z axis is defined vertical & downward in direction normal surface forces & gravity are the only forces involved 0 process variable load variable 0 emf resistance 0 time velocity d 1 17kPa/K 0.06kPa/K 0 Rise time overshoot b 1 37.1 lb/s 317 lb/s 0 52581 393308 0 1.5 inch 2 inches 0 50.5 58.6 0 233 degF 297 degF 0 QUESTION A B A valve that controls flow by means of a disk or wedge-shaped dam sliding at right angles to the direction of flow and seating tightly in the valve body is a gate valve butterfly valve The friction factor for flow through a pipe with relative roughness of 0.004 at a Reynold's No. of 80,000 is approximately equal to 0.052 0.025 The equation that relates friction factor and Reynold's No., f=64/Reynold's No. holds for smooth pipes laminar and turbulent flow Oil flows under laminar conditions inside a steam heated copper pipe. The overall heat transfer coefficient is approximately equal to the heat transfer coefficient of the oil the average between the heat transfer coefficient of the steam and that of oil In multi-stage liquid-liquid extraction with partially miscible solvents the extraction must be done to form co- currently in order to minimize the extraction. the minimum number of stages occur when the operating lines are parallel. The enrichment of the vapor steam as it passes through the column in contact with the reflux during distillation is called evaporation stripping The maximum number of plates for a given distillation system is obtained at variable reflux maximum reflux The correct unit for the specific rate constant for the reaction A--->B determined to be first order is square liter/square mol/min square liter/square mol/square min 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 large effect little effect **ang kulit ah! =P For a cylinder where steady-state radial heat transfer takes place the heat flux is constant maximum heat transfer rate occurs at the surface **eh di nga? 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 separation plate theoretical plate Crystallization occurs in a solution that is concentrated **concentration happens when the amount of solvent in a solution is decreased unsaturated Mass transfer in a flowing fluid may be correlated by Sherwood, Nusselt and Reynold's No Peclet, Reynold's and Schimdt No The ratio of the average diameter of the feed to the average diameter of the product is the settling ratio discharge ratio The rate of formation of C for the reaction 2A + B ---> C is found to be rate=k(A)(B) ***cguro w/c is true ang tanong? Hehe*** the rate of formation of C is equal to the rate of disappearance of B the order of reactio is zero **how can u say so? A device for increasing the velocity of a fluid in steady flow is a nozzle vent **ang vent ay butas? Di sisingaw? Babagal lalo ang velocity, meh singaw eh. In steady-state backmix flow reactor, composition is not constant throughout the reactor constant throughout the reactor The amount of money obtainable from the sale of used property over and above any changers involved in removal and sale is called net value salvage value In fractionation, an increase in reflux ratio increases the number of theoretical plates decreases the reboiler duty In mass transfer where the solute in the gas phase is very soluble in the liquid phase ***cguro w/c is true ang tanong? Hehe*** the ratio of liquid phase resistance to the overall resistance is close to unity the gas phase resistance is approximately equal to the total resistance Heat transfer in turbulent flow may be described through an empirical equation correlating Nusselt, Stanton and Reynold's Nos Nusselt, Prandtl and Reynold's Nos Which of the following fittings exhibits the highest pressure drop for the same flow conditions? 90-degree long radius elbow **K = 0.45 90-degree standard elbow **K = 0.75 A chamber into which steam from a high pressure line can be bled during periods of low steam demand from the power plant is called switching bank vent Which one of the following pipes has the highest relative roughness? 2" diameter Wrought iron pipe 4" dia Wrought iron pipe In steady-state heat transfer through a series of materials with varying resistances, the heat transfer rate decreases towards the direction of heat transfer varies with the thermal conductivity of each material Reactions whereby reactants proceed along several paths and give different products are polymeric reactions reversible reactions Which one among the following materials has the best insulating property? window glass wood An operation where warm vapor mixture is cooled such as by contact with a liquid resulting in condensation and decreased humidity is evaporation dehumidification The pressure exerted on a plane parallel to the direction of flow of a moving fluid is called gauge pressure velocity pressure For mass transfer to take place, there must be a phase change reaction component 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 212 deg F 80 deg F The diffusity of water in air at 100 deg F in sq.cm./sec is 0.256 0.278 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 5.9 2.5 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 66.6 58.1 When 32 kg of methane is burned completely the theoretical oxygen required is 16 kg 64 kg 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 32.2 31.4 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 4 2.18 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 over 100,000 but less than a million over 100 but less than 200 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 0.0378 0.0504 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 4440000 5130000 This is a steady state temperature reached by a small amount of liquid evaporating into a large amount of unsaturated vapor-gas mixture. wet-bulb temperature dew point 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 74.3 75 In adiabatic humidification, it is possible to maintain the temperature of water constant since according to the phase rule, the degrees of freedom is 3 the system can be well insulated from the surroundings 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 0.1 0.05 The portion of water in the wet solid that cannot be removed by the air in its contact is called free moisture final moisture content This type of drier is used for drying pasty materials such as wet filter cakes and lumpy solids rotary drier flash drier In the constant-rate period, the rate of drying is established by 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 desorption surface tension 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 0.542 hrs 1.846 hrs 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 0.12 0.034 In drying at the falling rate period, the rate at which moisture is removed from the solid material remains constant increases with time 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 to reduce the solid to the smallest size feasible to use counter current operation 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 0.3 0.8 Tung meal containing 55% oil is to be extracted at the rate of 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 3 4 The movement of molecules over a substantial distance is associated with the transfer of heat by convection conduction The mode of heat transfer that can take place in a vacuum is known as convection conduction The overall conductance for a composite material in series is equal to the sum of the individual conductances sum of the individual conductivities Film and drop are terms associated with boiling condensation A 6-in Sch 80 steel pipe is carrying glycerin at an average 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. 99.95 415.7 An oak (k=0.096 Btu/h-ft-degF) door, 30 in wide, 78 in high, and 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. 97 242 Determine the length needed for a simple concentric-tube, 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. 185.5 m 11.02 m A saturated solution containing 1500 kg of potassium chloride at 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. 4301 kg 1500 kg An evaporator, working at atmospheric pressure, is to 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. 55.8 sq.m. 58.5 sq.m. 2.5 kg/s of a solution at 288K containing 10% dissolved solids is 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. 115 kPa 101.3 kPa An acetone-air mixture containing 0.015 mol fraction of acetone 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? 10.92 9.12 A still has a liquor composition of ortho-xylen 10%, meta-xylene 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. 37 38 A mixture of alcohol and water with 0.45 mol fraction of alcohol 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? 10 9 Prepared cottonseed meats containing 35% extractable oil are 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? 72.2 28.7 0.4 kg/s of dry seashore sand, containing 1% by weight of salt, 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? 0.492 0.429 Forty-five pounds per minute of water is heated from 60 to 180 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 hо of 1000 Btu/hr-sq.ft.-degF, calculate the inside heat transfer coefficient [Btu/hr-cu.ft-degF]. 2173 696 How many cu.ft. per minute of entering air is needed to 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. 12.54 12.68 Nicotine is to be extracted from water using kerosene. If 100 lb 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]} 64.5 54.6 We must cool 2500 gpm of water from 120 to 80 deg F. A 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. 77.2 150 We wish to build an economical cold room 20 ft square and 10 ft 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? 3537 8457 A colloidal solution is to be concentrated from 15 to 65% solids. 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]? 10500 35000 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. 38.1 18.3 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. 2951 1644 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. 2.21 1.35 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. 63 84 Determine the net positive suction head available to a centrifugal 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] 34.2 27.7 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]? 11.61 14.24 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? 113 227 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? 0.15 0.5 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 [B]=0.4(1-x )/(1- 0.5x ) [B]=0.4(1-x )/(1- 1.5x ) Heat is generated in a 2.5 cm square copper rod at the rate of 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. 75.2 55.2 A 5cm diameter cylinder is maintained at a constant temperature 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/m-degC). 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]. 13 272 A building wall consists of a 6-in of concrete (kc= 0.7 Btu/hr-ft-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]. 0.028 0.119 Current is passed through a cylindrical laboratory heater, which 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]. 325 300 A straight rectangular fin has a length of 3.5 cm, a thickness of 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. 1500 W 4392 W A gaseous fuel is composed of 20% methane( CH4), 40% 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. 1 18 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]. 170 100 Two rooms A and B of identical volume are connected by an open doorway. The thermostat in the rooms are set so that Ta<Tb. Which room contains more air molecules? A B If the absolute temperature of a gas is doubled, the mean speed of the gas molecules is doubled. increases 4 times When ice cubes melt in a glass of water, the temperature of the resulting mixture of water and ice increases. decreases. In all naturally occurring processes, the entropy of the universe increases. decreases. An inventor seeking a patent claims that a building may be comfortably heated in winter by a device that draws heat into the building from the earth, even though the temperature of the earth is lower than the desired temperature inside the building. He further claims that the quantity of heat supplied to the building in a given time period can significantly exceed the work done by the device during the same period. If you were a patent clerk (like the young Albert Einstein), what should be your recommendation about the application? The application should be rejected because it violates the first law of Thermodynamics. The application should be rejected because it violates the second law of Thermodynamics. A fixture containing an ordinary incandescent light bulb is connected to a dimmer switch. The dimmer is adjusted so that the temperature of the tungsten filament inside the bulb increases from 1300K to 2600K. The total power radiated by the bulb doubles. quadruples. A 30 MW geothermal electric power plant uses hot steam from the earth at 157 deg C to heat and vaporize isobutane, which turns a turbine that is connected to a generator. The isobutane is subsequently cooled to 27 degC using fans and condensed back to a liquid. The overall efficiency of the plant is 40% of the ideal (Carnot) efficiency. How many joules of heat must be released to the atmosphere per second? 2.5 e8 2.2 e8 The material which remains unchanged in a process is limiting reactant tie substance The ratio of the total quantity of a reactant present in the reactor feed of a recycling operation to the quantity of the same reactant entering the operation as fresh feed is the recycle ratio combined feed ratio The heating value measured when water formed from combustion is in the liquid state. Gross Calorific Value Heat of combustion In the combustion of solid fuels, the tie element between the feed and the refuse is the cooked coal ash The coal analysis which is based upon the volatilization characteristics of the fuel is Proximate analysis Modified analysis An Orsat analysis of the flue gas when pyrite is roasted is on a SO2-free basis SO3-free basis The empirical relation which allows one to compute for the net hydrogen in a given solid fuel is the Calderwood equation Theoretical Oxygen Equation The equivalent of 45degTw in the Baume scale is 26.63 28.32 A furnace completely burns coal containing 70%C. Analysis of the flue gas shows 15% CO2, 4% O2, 81% N2, and no CO. What is the % of the net hydrogen in the coal? 1.2 1.53 Which has the lowest water content? dew point at 20degC 70% RH A contract was made between a buyer and a paper manufacturer for paper containing 5% moisture at PhP450/tonne FOB on specifications that price adjustment will be made if the quality is different. How much should the buyer pay for 1 tonne of paper with 8% moisture content? Freiht cost is PhP45/tonne. PhP 405 PhP 424.26 One drier will dry a material from 45% moisture (wb) to 20% moisture (db). From here the material enters another drier where the water content is further reduced to give a final product weighing 1000 kg. If the total evporation from both driers is 800 kg, the moisture of the final product is 0.01 0.02 An experimental oil is used to distill 6000 kg.hr of Athabasta tar sand which analyzes 30% 'heavy oil', 'light oil', and non-volatile matter. If the distillate contains 12 % heavy oil and this constitutes 25% recovery of the component, the weight in kg of the distillate obtained is 2250 3750 Coal fired in a furnace has a heating value of 13800 Btu/lb and contains 78.05%C and 1.2%S. The proximate analysis shows 4%M, 24%FC, 8%A and the analysis of the refuse shows 8%VCM, 25%FC and 32% ash. Calculate the % of C lost in the refuse. 4.22 8 Ninety grams of ethane and 384 grams of oxygen are fed continuously to a laboratory furnace. The total combustion products collected was 16.2 gmole with no carbon dioxide. However, not all of the ethane was burned due to faulty combustion. The fraction of ethane that was burned is equal to 0.8 0.85 The furnace at the Bataan refinery is using a fuel gas which contains methane, ethane and 20% nitrogen. The orsat analysis of the combustion products showed 7.8% CO2, 7.4% O2, and 84.8% N2. The gas is burned with excess air. The % methane in the fuel gas is 63.25 57.24 Pyrite containing 78% FeS2 and 22% gangue is burned with excess air to produce a stack gas with the following analysis: 7.29% SO2, 8.92%O2, 82.44%N2 and 1.35%SO3. If the cinder was found to have a partial analysis of 62.10% Fe2O3, the % of FeS2 lost in the pyrite is 3.52 6.53 The unit of k for a 1st order elementary reaction is 1/time conc/time If the temperature of a chemical reaction is raised by 10 degC, the rate of reaction is increased by a factor of 4 3 The E of a reaction may be lowered by increasing temperature decreasing temperature The mechanism of a reaction can sometimes be deduced from the activation energy the temperature dependency of the rate The equilibrium constant in a reversible chemical reaction at a given temperature depends on the initial conc of the reactants depends on the conc of one of the products at equilibrium If the volume of a reaction vessel is suddenly reduced to one half its original volume the rate will increase by a factor of 2 4 The rate of reaction is not influenced by conc of the reactants molecularity of the reaction The net rate of reaction of an intermediate is 0 2 A reaction is known to be first order in A. A straight line will be obtained by plotting log Ca vs time Ca vs time If the reaction 2A ---> B+C is second order, which of the following plots will give a straight line? Ca^2 vs time 1/Ca vs time 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 -ra = k Ca^2 Cb^4 -ra = k Ca Cb^2 It states that the rate of a chemical reaction is proportional to the activity of the reactants. Le Chatelier's principle Hess' Law The half life of a material undergoing second order decay is proportional to the square of the initial conc independent of initial conc 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. 66.8 74.7 A first order reaction has a specific rate constant of 3e-3 per sec. The half life is 0.0021 s 100 s 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 45.1 min 19.6 min 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 3.83 7.43 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. 25.36 m 32.5 m The set of data given below is for the parallel reaction: a---k1-->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 0.1697 0.183 A batch reaction 2D+E----->F has a conversion factor expressed 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 257 275 A container holds 100 gal of salt solution containing 50 lb of 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 0.732 0.427 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 10.3 11.4 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. 8150 9150 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? Cao/2m Cao/(2m-1) 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 43.1 41.3 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 1/8 1/16 When two centrifugal pumps are connected in series, the discharge changes by a factor of 1/2 1 When two reciprocating pumps are connected in parallel, the volumetric capacity of the system changes by a factor of 1/2 1 The pressure drop in a pipeline changes by a factor of _____ when the velocity of the flowing fluid is doubled. 1/2 1 Cavitation occurs in a centrifugal pump when the discharge pressure becomes too high the discharge valve is closed 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. 0.63 13.1 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. 1.05 1.22 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. 0.6 3.58 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. PhP 3300 PhP 5000 When the impeller speed of an ideal centrifugal pump is doubled, the vol. flow rate of discharge is increased by a factor of 1/2 1 The differential height between two points which a fluid has to be transferred is the potential head pressure head The resistance of a layer of fluid to flow over the next layer is measured by viscosity friction factor 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 20 36 Specify the type of open impeller pump to use if the capacity is 400 gpm at a head of 200 ft of water. 3x2x8.5E 4x3x8.5E 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. 95 134 If the speed of a centrifugal pump is doubled, the energy requirement becomes approximately ___ times the original energy requirement. 2 4 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. 32 55 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. 15 20 The rate of evaporation at a given operating temperature in a n evaporator is more when when the operating pressure is high the operating pressure is low An optimim number of the effects for a given application is a function of the capacity economy A popular type of heat exchanger for cooling large quantities of fluid is the double-pipe plate An evaporator is used to concentrate 10,000 lb/hr of a 20% solution of NaOH in water at 140 o F using saturated steam at 25 psia at a rate of 7,000 lb/hr. The OHTC is 275 BTU/hr-ft 2 - o F when the pressure in the vapor is 1.7 psia. The steam economy, SE, is 0.82 0.863 A cross flow heat exchanger uses mixed air at 4 kg/s that enters at 15 o C and leaves at 45 o C. The air cools unmixed water, which enters at 95 o C and 0.70 kg/s. The OHTC equals 150 W/m 2 - o C. After several months of operation, a scale resistance of 0.002 m 2 - o C/W developed. 16. The heat transfer area required to accomplish the change is 22.2 m 2 25 m 2 As solution of 28% wt Na 2 SO 4 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 o F and cooled to 60 o F using cooling water which enters at 50 o F and leaves at 70 o F. 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 285.3 249.3 An insulator should have low thermal conductivity high thermal conductivity Fouling factor is a dimensionless quantity does not provide a safety factor for design Natural convection is characterized by Reynolds number Grashhoff number The Graetz number is concerned with mass transfer between a gas and a liquid absorption with chemical reaction Dropwise condensation occurs on clean and dirt free surfaces smooth clean surfaces Dietus-Boelter equation for determination of heat transfer co-efficient is valid for liquid metals for fluid in laminar flow A type of pneumatic conveyor system characterized by a material moving in an air stream or pressure less than ambient. fluidizing pressure If the total percentage of particles larger than the screen opening in the feed, oversize, undersize are 36%, 89% and 3%, respectively, the effectiveness of the screen if the undersize is the product is 0.98 0.89 The estimated width of an apron conveyor having a capacity of 75 tons/hr at a speed of 50 ft/min is 305 mm 610 mm It is defined as the ratio of the average diameter of the feed to the average diameter of the product. settling ratio screen-mesh no The sphericity of cubical particles is 1 0.87 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 thickening classification 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? temperature pressure Ordinary diffusion takes place because of ___ driving force. temperature pressure What are the two limiting cases of steady-state diffusion? UMD and EMD ordinary and Knudsen Which of the following is not true in (binary) equimolar counter- diffusion? D AB = D BA c = c A + c B 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? Knudsen region turbulent region In unsteady-state mass transfer, the quantity (D AB t/r m^ 2 ) is referred to as unaccomplished change relative resistance What is the equivalent of Prandtl number in convective mass transfer? Sc Sh If k x > k y , then the controlling phase is the liquid phase the gas phase In two-phase mass transfer, equilibrium may exist at the interface in the gas phase Which of the following processes may always be regarded as a constant- humidity process? cooling of air air conditioning 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 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? dry-bulb temperature wet-bulb temperature The moisture content of a solid is given as 50% wet basis. What is the moisture content, dry basis? 0.5 1 The moisture that can be removed by drying is called equilibrium moisture bound moisture Falling-period in drying terminates at the end of constant- rate period origin of R vs X plot 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 the solute concentration of the liquid is less than that of the bulk He and N 2 gas are contained in a conduit 5 mm in diameter and 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 2.35 exp -5 2.44exp -5 100 m 3 /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 5280 8490 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. 1 hr 1.6 hr The unit of volumetric diffusivity is cm^ 2 /sec cm/sec If reflux to a distillation column is 100 moles/hr, when the overhead product rate is 50 moles/hr. the reflux ratio is 0.5 2 Which of the following provides maximum contact surface for a liquid- vapour system? packed lower bubble-cup plate column In extraction, as the temperature increases, the area of heterogeneity (area covered by bimodal curve) decreases increases The suitable evaporator for concentration of foaming liquids is long tube evaporator short tube evaporator Macroscopic transfer of mass between moving fluid and surface which is of different concentration is called molecular diffusion unsteady-state diffusion For a packed column the main purpose of packing is to strengthen the column increase the surface area In a gas absorption operation, when the operating line crosses the equilibrium curve the NTU is zero the liquid flow rate is maximum Methanol diffuses in 0.15 cm stagnant film of 1:1 mole mixture of hydrogen and CO 2 at 100 o C 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 o C and 1 atm in cm 2 /s is 0.15 0.31 Gaseous reactant A decomposes according to the reaction A --> 3R (-r A = 0.5 C A 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? 0.92 0.86 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? 14.7 18.5 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. 0.54 min 0.85 min For Newtonian fluids, the shear stress is constant. inversely proportional to rate of deformation. An ideal fluid is one that is compressible incompressible & viscous 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 10.58 5.29 An imaginary line within a fluid flow such that a tangent at any point indicates the direction of flow at that point. stream tube velocity profile Air at 25 0 C [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? 350 155 A simple pitot tube measures acoustical velocity superficial velocity Which of the following meters will have the highest permanent pressure loss? pitot tube orifice In the flow meter equation, Y, indicates the mass flow rate compressibility factor The loss due to sudden contraction is proportional to velocity turbulence Stoke’s law is valid when the particle Reynolds number is < 1 > 1 Priming needed in a Reciprocating pump Gear pump Maximum theoretical suction lift for water at 60˚F by a centrifugal pump is 34 ft. The same for water at 200˚F will be 40 ft 37 ft The most economical valve for use with large diameter pipes. butterfly globe Multistage compressors are used in industry because, they reduce the cost of compressor reduce the size requirement For ideally incompressible fluid, the mach number will be 0 1 of the following produces maximum pressure difference for transportation of gases? vacuum pumps blowers The fluid property which matters for falling rain drops to acquire spherical shape is its pressure height of descend A wastewater solution having a volume of 1000 L contains 0.21 kg phenol/m 3 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? 0.007 kg 0.106 kg The overhead product composition decreases with time in batch distillation with reflux continuous distillation with reflux For a binary mixture with low relativity, continuous rectification to get pure products will require low reflux ratio small cross-section Chemisorption is the same as van der Waals characterized by adsorption of heat The stage efficiency in leaching depends on the time of contact between the solid and the solution rate of diffusion of the solute through the solid and into the liquid Weeping in distillation or absorption column increases tray efficiency provides larger surface for mass transfer What are the two contacting phase in leaching? extract phase and raffinate phase solvent phase and solute phase Hydrogen sulfide is removed from water by contacting the solution with warm air. The operation is Distillation Leaching Disregarding the cost, which is the best solvent for the extraction of acetic acid from an aqueous solution at 25deg C? caproic acid chloroform 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 reactor and for three years, sold many units to the public can still patent his reactor. TRUE FALSE A person who has passed the Chemical Licensure Examination can take his/her oath as a chemical engineer if his/her age is not less than _______ years. 18 19 Which of the following is not a requirement for utility model registration? inventive step novelty A section of the patent application containing detailed descriptions of the benefits obtained from using the invention is called the disclosure abstract A document issued by the DENR secretary indicating that the proposed project will cause significant negative environmental impact. Environmental Impact Statement Environmental Compliance Certificate In the Philippines, sulfur for sulfuric acid manufacturing is sourced from _______ industry. paper cement Sulfur is undesirable in petroleum because it causes engine knocking it increases the boiling pt of fuel Materials added to detergent formulation to enhance cleaning performance by exhibiting synergistic cleaning effect with surfactant. fillers brighteners Polyethylene is an example of _____________ polymerization condensation addition Principal chemical conversion in the production of resin from monomer. condensation hydration Carbon black is added to rubber compounding as activator curing agent The binder for all the powder materials of paint pigment vehicle A fibrous material left after cane sugar has been milled is commonly called as bagasse pulp Molasses is a by product of raw sugar from the ______ process milling extraction Kraft process is a common name for sulfate pulping sulfite pulping Water insoluble cell binders of wood pulp cellulose DDT means Diphenyldichlorotri phenylethane dichlorodiphenyldic hloroethane Rancidity of oil can be reduced by decoloration hydrogenation Varnish does not contain pigment dryer Plasticisers are added to paints to make it corrosion resistant make glossy surface Silicone is thermoplastic a monomer The process involved in converting rubber into a thin sheet or coating it on fabric is called extrusion mastication Alkyl benzene sulfonate (ABS) is a detergent rubber Neoprene is a monomer synthetic rubber Steam enters an adiabatic turbine at 10 MPa and 500 deg C 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. 0.2348 0.3216 Work is a property of the system path function Throttling process is a reversible and isothermal process an irreversible and constant entropy A sample consisting of 1.00 mole of Argon gas is expanded isothermally and reversibly at 0°C from 22.4L to 44.8L. The heat absorbed by the system is 0 +1.13 kJ Maximum work can be obtained from a system when the change taking place in it is isothermal adiabatic The ratio of work performed by a system and the heat it absorbed from a reservoir is referred to Entropy Gibb’s free energy According to the first law of thermodynamics Energy is neither lost nor gained in any energy transformation. Perpetual motion is possible. 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 greater than 0.85 in between 0.75 and 0.85 In choosing the refrigerant, the fluid must have the following characteristics, except environmentally benign has a vapor pressure less than atmospheric Coolers and boilers are ordinarily operated at ________ condition. isobaric isenthalpic For an isolated system, maximum entropy will occur at half-life critical condition A carnot cycle consists of two isothermal and two adiabatic process two isochoric and two adiabatic process This is also known as the volume fraction of the voids in packed beds. sphericity porosity A measure of the ratio of the drag force acting on a unit area of the impeller & the inertial stress. Froude number Reynold’s number Sulfuric acid is pumped at 3 kg/s through a 60-m length of 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. 3 2 The equation del(P) = -(rho)(g) del(z) is known as the hydrostatic vertical law for which all the following assumptions are applied, except shear forces are not involved fluid is incompressible Which of the following can be adjusted by human operator in a closed feedback control loop? set point controller output 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. current temperature Dead time is a function of distance and momentum acceleration A pneumatic controller is used to control temperature within the 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? 2.83kPa/K 0.35kPa/K The parameter which completely describes the behavior of the response to a disturbance of a second order system is the Time constant damping coefficient C D Comments! globe valve orifice a ! Un na nga ang gate valve. =P 0.03 0.038 E ! The correct answer is about 0.0095 from perry 8th fig 6.9 pge 6- 10 tingnan nyu pa turbulent flow only laminar flow only X ! Meron gang f=64/Re? baka f = 12/Re eto eh "Hagen-Poiseuille Equation" for SMOOTH TUBES & LAMINAR FLOW from perry 8 same page ng nasa taas. equal to the heat transfer coefficient equivalent to the resistance offerred by the pipe equal to the heat transfer coefficient of the steam d xxx 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. b xxx rectification fractionation c xxx minimum reflux optimum reflux c xxx mol/liter/min liter/mol/min E ! 1/time k = (Volume (order -1) ) / (Concentration (order -1) ) x time no effect significant effect c ! Eh constant nga ung temp nung isang stream..=P btw.. ∆T lm = [∆T (side a) - ∆T (side b) ] / ln [∆T (side a) / ∆T (side b) ] a------ --------------->b a--------------------->b a----- ---------------->b a<---------------------b the heat transfer is constant **panu pag iba na ang heat transfer area? the temperature is uniform throughout the cylinder **sinong nanay mo? a ! Steady State daw ang heat transfer… so steady o constant din ang Heat Flux. Bakit hindi ung c? kasi di pwedeng sabihin na heat transfer eh constant kasi ang heat transfer eh q lang. Samantalang ang Heat Flux eh q/A. ***Amount of Heat Transfer = Heat Flux x Area of Heat Transfer *** *** q = (q/A) x A *** transition plate bubble plate d xxx supersaturated saturated c ! Sturated --> Solute = Solvent Unsaturated --> Solute < Solvent Supersaturated --> Solute > Solvent **based on solubility*** Sherwood, Reynold's and Schimdt No Prandtl, Schimdt and Reynold's No c ! Look at p 5 - 63 to 5 -82 of perry 8th. Specifically, note the dimensionless numbers being used at every MTC formula. N sh N re N sc reduction ratio classification ratio c ! Malamang =P the value of k is independent of the initial concentrations of A and B the reaction cannot proceed **isa ka pa^^ c ! Kelan ga naging dependent ang k sa initial concen ng kahit na alin sa reaction? Sa Temperature lang dependent ang k**. Kaya nga ang tawag sa k ay "specific rate constant" dahil specific sya sa isang temp at sa isang reaction at sya ay constant! Hehe **from Arrhenius eqn : lnk = - (E A / R) (1 / T) + lnk o orifice **pabibilisin nga, haharangan pa xD venturi **meter? hehe a ! Nozzle - ex. Pipe na papaliit ang diameter, papaliit din malamang ang cross sectional area, at papabilis ang velocity ng fluid. ***flow of incompresible fluids*** mass flowrate = density x Area x velocity a function of time not uniform throughout the reactor and varies from time to time b ! Bacmix Reactor is another name for CSTRs (Constantly Stirred Tank Reactors) wherein ther is a constant composition throughout which is assumed due to constant stirring. book value market value b xxx increases the amount of distillate increases the condenser duty ? xxx the gas phase resistance is negligible the ratio of gas phase resistance to liquid resistance is approximately zero ? xxx Peclet, Stanton and Prandtl Nos Schimdt, Peclet and Friction Nos b ! Sila yung gamitin sa Heat Transfer by convection. See perry 8th p 5.7, Heat transfer by conduction. N u N re N Pr 45-degree standard elbow **K = 0.35 square-corner elbow **K = 1.3 d ! The higher the K (additional friction loss) the higher the pressure drop. See page 6 -18 perry 8th. compressor accumulator 1" dia Drawn tubing 4" dia Riveted steel pipe through each material is inversely proportional to the thickness of the material is constant throughout the series of materials parallel reactions consecutive reactions air concret b humidification extraction b tangential pressure static pressure b concentration gradient momentum gradient c 113 deg F 146 deg F 1.484 0.581 b 1.5 0.6 33.4 54.4 128 kg 32 kg c 26.4 57.8 1.5 2.75 over 20 million over 2 but less than 3 0.0454 0.0252 6930000 2040000 saturation temperature dry-bulb temperature 75.26 78.5 the temperature of the air can also be maintained constant increase in the humidity of the air is insignificant 0.02 0.01 equilibrium moisture content critical moisture content c tray drier freeze drier c air flow perpendicular to the surface of the solid air flow parallel to the solid surface surface renewal moisture diffusivity d 2.129 hrs 3.42 hrs 0.01155 0.00116 decreases with time no drying takes place to use cross flow evaporation to use spray percolators 1.5 2.3 5 6 radiation all of A, B and C a radiation all of A, B and C c inverse of the total resistance sum of the individual resistances c evaporation all of A, B and C b 451.7 475.1 5800 139200 5.51 m 4.14 m 966 kg 534 kg 85.8 sq.m. 88.5 sq.m. 14 kPa zero gauge 4.72 3.03 39 40 8 7 27.8 22.7 0.294 0.249 577 241 13.76 16.28 46.5 45.6 227.2 300 11994 20451 40130 45500 13.8 5 1163 19.4 4.67 2 95 100 7 0.52 31.7 37.1 851 900 0.75 1 [B]=0.4(1-0.5x )/(1- x ) [B]=0.2 25.2 20 3478 3750 0.714 6.01 100 25 13943 W 19343 W 23 33 38 0.038 both contain the same no of air molecules increases by about 40% decreases. stays constant. c stays the same. may increase or decrease. a 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 Thermodynamics. increases 8x. increases 16x. 3 e7 5.2 e8 excess reactant product yield b reactant ratio fresh-feed conversion b Latent Heat of Condensation Net Calorific Value a moisture volatile combustible matters b Ultimate analysis Elemental analysis O2-free basis N2-free basis b Dulong's formula Oxygen unaccounted for equation 32.48 42.56 2.38 6.13 absolute humidity of 0.05 60% saturation PhP 434.16 PhP 450 0.03 0.05 4350 6000 9.5 17 0.9 0.92 51.2 22.76 7.86 23.1 1/conc 1/conc-time a 2 1.5 adding a catalyst removing the products of the reaction the net equation the rate law. does not depend on the initial concentrations is not a characteristic of the reaction c 8 16 d nature of reactants temperature > 0 <0 log Ca vs reciprocal time 1/Ca vs time lof Ca vs time Ca vs time -ra = k Ca -ra = k Cb^2 Law of Mass Action Second Law of Thermo c proportional to initial conc inversely proportional to initial conc 85.3 99.1 231 s 768 s 19.1 min 10.4 min 8.33 9.33 52.63 m 56.23 m 0.3394 0.6197 300 527 0.327 0.237 12.7 20.7 9550 10150 Cao/(1-2m) Cao/2 37.1 31.8 1/32 1/64 2 4 2 4 2 4 the suction pressure is too high suction is lost 16.9 87.2 1.72 1.89 21 58.3 PhP 7000 PhP 12000 2 2exp2 velocity head dynamic head surface tension drag coefficient 63 85 4x3x6 3x2x13 248 320 8 10 77 94 25 30 there is a vacuum when the liquid level is high efficiency none of the given choices shell and tube extended surfaces 0.89 0.92 17 m 2 20 m 2 255.65 214.65 less resistance to heat flow a porous structure a accounts for additional resistance to heat flow none of these Peclet number Prandlt number b heat transfer in turbulent flow heat transfer in laminar flow d contaminated cooling surfaces polished surfaces c for fluids in turbulent flow when Grashhoff number is very important pressure-vacuum vacuum d 0.76 0.65 1220 mm 2400 mm reduction ratio average particle diameter c 0.7 0.6 a sorting centrifugation a concentration electric field concentration electric field c thermal and ordinary thermal and Knudsen J A = J B N A = -cD AB dx A /dz buffer region viscous sub-layer relative time relative position Bi Pe the interface either of the bulk phases in the liquid phase in either film water-cooling in a cooling tower heating of air dehumidification and removal of sensible heat dehumidification by condensing water vapor in a refrigerator adiabatic saturation temperature dew point temperature 2 50 b xxx free moisture unbound moisture c critical free moisture content equilibrium moisture content the solute concentration of the liquid and gas phase are equal the solute concentration of the gas is greater than the liquid 1.77exp -6 1.22 exp -6 10050 11570 2.3 hr 2.9 hr cm^ 3 /sec cm^ 2 /sec^ 2 50 150 sieve-plate column wetted wall column remains unchanged vacuum evaporator falling film evaporator convective mass transfer all of these increase the pressure drop in the tower reduce the flow rate across the column the gas flow rate is maximum the number of stages is infinite 0.51 0.68 0.71 0.65 20.9 22.4 0.87 min 1.18 min equal to shear rate of deformation. a linear function of the shear rate of deformation. d incompressible incompressible & inviscid d 1.84 0.25 streamline none of these 101.3 61 mean linear velocity local velocity d venturi rotameter b coefficient of discharge cross-sectional area velocity head static head c < 5 0 Centrifugal pump Diaphragm pump 34 ft 8 ft needle gate resemble closely to isothermal compression are easy to control 1.5 5 b fans compressors d viscosity surface tension d 0.189 kg 0.198 kg continuous distillation without reflux distillation operating at total reflux less number of trays high reflux ratio an irreversible phenomenon always in equilibrium c both A and B either A or B because these two mean the same thing results due to low gas velocity is due to bubble cups feed phase and solvent phase overflow and underflow Absorption Stripping d 3-heptanol toluene P.D. No. 232 P.D. No. 826 it depends not governed by law 21 23 industrial applicability a technical solution to problem request claims Environmental Impact Assessment Environmental Critical Project petroleum detergents it poisons the catalyst in the refining process all that are mentioned a builders perfume c copolymerization natural b polymerization alkylation d retarders fillers a ! opacifier filler a ! cellulose waste c ! evaporation crystallization c bleaching calendering b xylem lignin d Dichlorodiphenyldi chlorobutane diphenyldichlorotriphe nylbutane c oxidation purification b thinner anti-skinning agent a increase atmospheric oxidation give elasticity and prevent cracking of the film d an inorganic polymer thermosetting plastic c vulcanization calendering d pesticide polyester a polyester pigment b 0.6784 0.7652 state function state description of a system b a reversible and constant entropy process constant enthalpy process +1.57 kJ +2.27 kJ reversible irreversible c carnot efficiency Helmholtz free energy c Energy is conserved in quality but not in quantity. Energy is being created as time passes. We have more energy in the universe now than when time began. less than 0.75 in between 0.84 and 0.90 must be economically viable exist at a high pressure at the condensation temperature isothermal isentropic a equilibrium start of the process c one isochoric, one isobaric, and two adiabatic process one isothermal, one isochoric and two adiabatic process superficial velocity specific volume b Mach number Power number 0.2 0.124 z axis is defined vertical & downward in direction normal surface forces & gravity are the only forces involved process variable load variable emf resistance time velocity 17kPa/K 0.06kPa/K Rise time overshoot b xxx legend: X = something wrong with the question E = answer is not on the 4 choices xxx = bakit kaya? if there is any revisions on answers, kindly inform me. Itama nyu naman pag mali ako. Baka nagiimagine lang ako ng formula. Hehe xxx puro to kalokohan ha.. Hehe ! I found this thing on August 8, 09 and I started answering the blank parts and correcting the wrong ones since then. ---------------------------------------------------------------boja--- la lang ^^