HEAT TRANSFER1. A 15 cm thick wall has a thermal conductivity of 5W /m-°K. If inside and outside surface temperature of the wall are 200°C and 20°C, respectively. Determine the heat transmitted.Answer: A A. 5.67 KW/m2 B. 4.68 KW/m2 C. 8.87 KW/m2 D. 6.87 KW/m2 2. Two walls of cold storage plant are composed of an insulating material (l = 0.25 KJ/hr-m-°C), 100 mm thick at the outer layer and material (l = 3.5 KJ/hr-m-°C), 15 cm thick at inner layer. If the surface temperature at cold side is 30°C and hot side is 250°C, find the heat transmitted per square meter.Answer: A A. 0.138 KW/m2 B. 0.450 KW/m2 C. 0.025 KW/m2 D. 0.065 KW/m2 3. Sea water for cooling enters a condenser at 27°C and leaves at 37°C. The condenser temperature is 45°C, what is the log mean temperature difference?Answer: B A. 50.65°C B. 12.33°C C. 37.82°C D. 80.54°C 4. Determine the thermal conductivity of a material that uses a 2 m2 test panel, 25 mm thick with a temperature difference of 10.8°F between the surfaces. During the 5 hours test period, the heat transmitted is 200 KJ.Answer: C A. 0.045 W/m-°K B. 0.560 W/m-°K C. 0.023 W/m-°K D. 0.370 W/m-°K 5. A steam pipe having a surface temperature of 200 °C passes through a room where the temperature is 27°C. The outside diameter of pipe is 80 mm and emissivity factor is 0.8 Calculate the radiated heat loss for 3 m pipe length.Answer: A A. 1434.47 W B. 2746.35 W C. 2756.57 W D. 3546.45 W 6. A counter flow heat exchanger is designed to heat fuel oil from 30°C to 90°C while the heating fluid enters at 140°C at 105°C. Determine the arithmetic mean temperature difference.Answer: B A. 72.5°C B. 62.5°C C. 45.5°C D. 67.5°C 7. A heat exchanger has an overall coefficient of heat transfer of 0.50 KW/m2-°C. Heat loss is 11 KW and the mean temperature difference is 15°C. What is the heat transfer are in ft2?Answer: D A. 51.80 ft2 B. 37.30 ft2 C. 56.80 ft2 D. 15.80 ft2 8. Brine enters a circulating brine cooler at the rate of 60 m3/hr at -10°C and leaves at -16°C. Specific heat of brine is 1.072 KJ/kg-°K and specific gravity of 1.1. Determine the tons of refrigeration.Answer: C A. 53.5 TR B. 65.3TR C. 33.5 TR D. 44.5 TR 290 W/m2-°K Thermal conductivity of the metal wall. Calculate the log mean temperature difference. 165 14. 30 B.000 kg/hr per cylinder at rated load and speed. 762 w/m2 D.5KJ/kg-°C. If heat transmitted is 1000 W/m2. An oil heater heats 100 kg per minute of oil from 35°C to 100°C in a counter flow heat exchanger. 20mm D. Exhaust gases used for heating enter the heater with an average specific heat of 1 KJ/kg- °C.Answer: A A.80. The outside diameter of the pipe is 70 mm. 998 w/m2 B.Answer: A A. The overall heat transfer coefficient is 75 W/m2- °C. Cooling water enters air cooler at 30°C and leaves at 38°C. 354°C 10. 36 . A turbo-charged. 234°C D.Answer: C A. 295°C B. 465°C C. 872 w/m2 C. 47°C B. respectively. An uninsulated steam pipe passes through a room in which the air and walls are at 25°C. Vee type diesel engine has an air consumption of 3. 63 C. 422 w/m2 12. 10 mm B. 87°C C.000 kg/her per cylinder at rated load and speed. The temperature of the air from the compressor is 145°C and a counter flow air cooler reduces the air temperature to 45°C before it goes to the engine suction header. 123 D. The temperature of the air from the compressor is 145°C and a counter flow air cooler reduces the air temperature to 45°C before it goes to the engine suction header. The average specific heat of the oil is 2. 34°C D. 16 cylinder. what is the surface temperature on the wall at hot side?Answer: A A. This air is drawn in through a filter by a centrifugal compressor directly connected to the exhaust gas turbine. 40 D. 136 C. 1145°C Cold gas temperature is 45°C Unit surface conductance on the hot side. Cooling water enters air cooler at 30°C and leaves at 38°C. A turbo-charged. a mass flow rate of 250 kg/min and an initial temperature of 200°C.Answer: D A. and its surface temperature and emissivity are 200°C and 0. Vee-type diesel engine has an air consumption of 3. 115 W/m-°K Find the maximum thickness of metal wall between the hot gas and cold gas. Determine heating surface in square meters. 30mm C. A heat exchanger is to be designed for the following specifications: Hot gas temperature. 40mm 11. This air is drawn in through a filter by a centrifugal compressor directly connected to the exhaust gas turbine.9. 16 cylinder. what is the rate of heat loss from the surface per unit length of pipe?Answer: A A. 230 W/m2-°K Unit surface conductance on the cold side. 144 B. A heat exchanger has a hot gas temperature of 300°C and surface conductance on hot side is 200 W/m2-°K. 65°C 13. Calculate the quantity of cooling water in m3/hr required to cool the total requirements of the engine at rated load and speed. so that the maximum temperature of the wall does not exceed 545°C. If the coefficient associated with free convection heat transfer from the surface to the air is 15 W/m2-°K. Steam initially saturated at 2.2 W/m-°K and surface emissivity of 0.05 Mpa. 13.509 17.95 Btu/hr-ft-°F at the temperature interest.069 W/m-°K fo for still air = 9.4 cm at a velocity of 5m/sec at the temperature in the pipe.10 cm standard steel pipe for a total distance of 152 m.08 cm thickness of 85% magnesia.7 B.5°C. 623. 285 W/m2 B. 11. A surface condenser serving a 50. 14 C.000 kg/hr.5 C. which are at 25°C.67 Enthalpy: hf = 914.Answer: C A. Vacuum in condenser is 702 mm Hg.125 kg steam per second? Properties of steam: Pressure = 2. 96.3 20. Calculate the energy transfer rate across 6” wall of firebrick with a temperature differences across the wall of 50°C. what is the quality of the steam which arises at its destination if the mass flow rate is 0. 93% B.000 kg/hr. 16 16. 352.131 Pa-s.52 hfg = 1885.8.9 kg/sec. 10.374 B. For steam turbine condenser design. What is the brick inner surface temperature in °C?Answer: B A. What is the Reynolds Number for this situation?Answer: A A.000 KW steam turbo-generator unit receives exhaust steam at the rate of 196.345 D.5°C and leaves at 37. Sea water for cooling enters at 29. A surface condenser serving a 50. Under steady state conditions and outer surface temperature of 100°C is measured.000 KW steam turbo-generator unit receives exhaust steam at the rate of 196. For steam turbine condensed as heat given up to cooling water.445 C. 2241 B. manufacturers consider 950 Btu/lb of steam turbine condensed as heat given up to cooling water. The steam line is insulated with a 5.Answer: D A.2 C. Vacuum in condenser is 702 mm Hg. by a brick wall 0.Answer: B A. The density and viscosity of the water are as follows: density = 997. 256. 98% C. 12 D. 429 W/m2 18. 369 W/m2 C. 76% .0 k for 85% magnesia = 0.5 hg = 28000.36 W/m-°KAnswer: A A. Sea water for cooling enters at 29. Water is flowing in a pipe with radius of 25. 461. viscosity = 1. 12.15. 3100 D. 84% D.15 m thick. Calculate logarithmic mean temperature difference in °F. The brick has a thermal conductivity of 1. For an ambient temperature of 22°C. 10 B.4 D. 112 W/m2 D.5°C and leaves at 37. 1140 19.5°C.05 Temperature = 213. passes through a 10. Calculate the required quantity of cooling water in cubic meters per hour. The thermal conductivity of the firebrick is 0. Free convection heat transfer to the air adjoining this surface is characterized by a convection coefficient of 20W/m2-°K. The hot combustion gases of a furnace are separated from the ambient air and its surrounding. The specific weight is 28 kg/m. 40. 982. A pump is to deliver 150 gpm of water at ahead of 120 m. The suction pressure of a pump reads 2 in.30 m C. The final temperature of pipe is 195°C.54 kg D. 21. What is the heat transfer in the glass surface area of 0. determine the total suction head. 8. A centrifugal pump requires 40 ft head to deliver water from low level to higher level. Compute the amount of condensate formed during 10 minutes warm-up of 150 meter pipe conveys the saturated steam with enthalpy vaporization hfg = 1. 5014 rpm B.33 Hp . 5453 rpm C. 7. The pump centerline of a centrifugal pump is located 2.69 kg B. 6.7 KW C.45 kg 22. 423. A double suction centrifugal pumps delivers 70 ft3/sec of water at a head of 12 m and running at 1250 rpm. 2. If friction loss at the suction is 0. 3. If pump speed is 1600 rpm. 176 mm 4. 185 mm B.6 KJ/kg-°C. 2. The specific heat of pipe material is 0.8 LJ/kg.Answer: B A.8 W/m- °K.2 kw D. 25.Answer: C A.6 kw C.30 m B. 4.947.45 kg C. Answer: A A. what is the horsepower rating of motor required to drive the pump?Answer: D A.4 KW D. 5. What is the specific speed of the pump?Answer: D A.0163 ft3/lb.5 m above from the high tide level. determine the impeller diameter of the centrifugal pump. 5.4 KW 5. 9. 249.30 m D.66 Hp C. 5. The thickness of glass surface is 0. Determine the pump work. 160 mm C.21. 38. 6. The thermal conductivity is 1.34 kw PUMPS 1.8 kw B.44 Hp B.8 m.0007 m. of mercury vacuum and discharge pressure reads 130 psi is used to deliver 100 gpm of water with specific volume of 0.6 KW B.23 m 3.The minimum external temperature of pipe is 2°C. If pump efficiency is 70%.44 Hp D. 9968 rpm 2. The sea water varies two meters from high tide to low tide level.Answer: A A. 2345 rpm D. 154 mm D.Answer: D A. 294.7 m2 having an inside temperature (room) of 23°C and 13°C outside temperature (surrounding). 465 KJ/kg C. The pump was installed 120 ft below the ground level and a draw down of 8 ft during the operation.56 KW D.45 KW 11.64 KW D. 774 KJ/kg D. 7. Each impeller develops a head of 38 ft. 62. determine the increase in pump capacity.54 KW C.32 KW B. A boiler feed pump receives 50 li/sec of water with specific volume of 0. 643. 34. the enthalpy at the entrance is 765 KJ/kg. 354. 4.54li/sec . what is the increase in head?Answer: B A.00112 m3/kg at ahead of 750 m. 34. What is the power output of driving motor if pump efficiency is 65%?Answer: A A. 13. If water level is 25 ft above the pump. 356. Answer: B A. determine the pump power. 7 10.86 KW C. 864 KW 9. A motor is used to d rive a pump having an efficiency of 85% and 70 % respectively. IF pump speed will increase to 120 rpm.24 KW D.67 KW 12.Answer: C A. A submersible pump delivers 350 gpm of water to a height of 5 ft from the ground.50% C. what is the exit enthalpy of the pump. 61. 505.6. Determine the number of stages needed for a centrifugal pump if it is used to deliver 400 gal/min of water and pump power of 15 Hp. 897 KJ/kg B. 785.50% B. 65.13 KW B. 56. 356. A pump is used to deliver 50 li/sec of sea water at a speed of 120 rpm. 7.3 m 13. 43.Answer: C A.50% D. If pump has a head of 900 m.56 KW B.50% 7.Answer: D A.56 li/sec C. A pump running at 100 rpm delivers water against a head of 30 m. If speed will increase to 135 rpm. What power can a boiler feed pump can deliver a mass of 35 kg/s water at a head of 500 m?Answer: D A. 8 D. 87. 864 KJ/kg 8. 6 B. 171. What is the combined efficiency of pump and motor?Answer: A A. In a boiler feed pump. 4 C.54 KW C.2 m C. 56.2 m B.25 li/sec B. 59. 456.6 m D. Suction and discharge head loss are 0. Determine the speed of impeller if diameter is reduces from 305 mm to 254 mm. 240 KW 17. 2. A 15 KW motor running at 350 rpm is used to drive a pump.65 KW B. 14. 23.Answer: C A. determine the power needed by the pump. Water from a reservoir A 10 m elevation is drawn by a motor driven pump to an upper reservoir B at 72m elevation. 340 KW D. 3.2 lb/ft3. 12. For discharge rate of 15li/sec. What amount of energy must be furnished by the pump in KW?Answer: A A. 4675 KW D. A centrifugal pump is designed for 1800 rpm and head of 61m. 3456 KW 20. Pumping rate of the pump at 1000 rpm is 1. The discharge gage is 2 ft above the suction gage.Answer: A A. 480 KW C. Water from a reservoir is pumped over a hill through a pipe 900 mm in diameter and a pressure of one kg/cm2 is maintained at the pipe discharge where the pipe is 85m from the pump centerline. what power must be furnished by the pump?Answer: A A. 2. 1723 kw .17 KW D.67 KW 15.35 KW 19.45 Hp D. respectively. 1500 rpm D. 1234 kw D. 211 KW B. repectively. 1600 rpm 18.24 Hp B.260 li/sec 14.89 Hp 16. The discharge pipe of a pump is 400 mm in diameter delivers 0. 6. 1446 KW B. 5. 2546 KW C. The suction and discharge gage reads 4 in Hg vacuum and 25 psi. 56. If equivalent head is 2m.72 KW B. The elevation of suction reservoir is 5m above the pump centerline and delivers to 85m elevation tank which maintain 150 Kpa. 6. 45. If 1. 5. D. 1250 rpm C. 1523 kw C. 17. Friction losses is equivalent to 3m of head loss.45 KW D. A certain pump is used to deliver 150 gpm of water having a density of 61.67 Hp C.72 KW C. what is the increase in power?Answer: A A. 1372 kw B. If speed will be changed to 370 rpm. find the power input to the motor if overall efficiency is 65%. 1000 rpm B.5 m3/sec of water to a building which maintains a pressure of 100 Kpa at a height of 30 m above the reservoir.5m3/sec of water is used to deliver a total head of 3m.5 m3/sec. The pump has a positive suction head of 5m.54 KW C.15m. What is the brake power of the motor if pump efficiency is 75%?Answer: A A.Answer: C A. 453.850 kpa B. Determine power output of the driving motor in KW. 523.Answer: D A. 206 C. A pump is to deliver 80 gpm of water at 140°F with a discharge pressure of 150 psig. The discharge gage is located 2 feet above the center of the discharge pipe line and pump inlet and discharge lines are at the same elevation. 13.5 Hp if the pump has an 8 inches nominal size suction and 6 inches nominal size discharge if it handles 150 gpm of water at 150°F.33 hp C. 6.Answer: D A. The diameter of suction and discharge pipes are 5 inches. 2. Determine the water horsepower and the mechanical efficiency of a centrifugal water pump which has an input of 3. Water from a reservoir is pumped over a hill through a pipe 450 mm in diameter and a pressure of 1 kg/cm2 is maintained at the summit.5m head loss. For a discharge rate of 10li/sec. 7.57 C.39 kw 24. 4. Water discharge is 30m above the reservoir. 5. A boiler feed pump receives 40 liters per second at 180°C. 11.45 kw C. 2. The suction line has a loss of head three times that of the velocity head in the 200 mm pipe.23 D.Answer: D A. respectively. 8. Determine power input to the drive motor. 2. 208 22. 756.5 m3/sec.34 kw C. A boiler feed pump receives 40 liters per second at 4 Mpa and 180°C.59 kw D. Frictional losses in the discharge and suction pipe and pump is equivalent to 1. 8. 983. 6.27 27.34 C. It operates against a total head of 900 m with an efficiency of 60%. The pump has an efficiency of 70%. Determine discharge pressure in Kpa for a suction pressure of 4 Mpa.23 kw B. The quantity pumped is 0.34 hp 25.23 26. The discharge line has a loss of head twenty times that of the velocity head in the discharge pipeline. while the motor efficiency is 80%.Answer: A A. 765. Overall efficiency of the system is 78%. The inside diameter of the suction pipe is 200mm and 150mm for the discharge pipe. find the power input to the motor and the pressure gage reading installed just at the outlet and inlet of the pump in Kpag. 202 B.455 kpa C. The pump centerline is at 4m. 773.21. 783. It operates against a total head of 900 m with an efficiency of 60%. A boiler feed pump receives 40 liters per second at 180°C. 9. Determine the enthalpy leaving the pump in KJ/kgAnswer: B A. Water from an open reservoir A at 8m elevation is drawn by a motor-driven pump to an open reservoir B at 70m elevation. 623. Suction pressure indicates 2 inches of mercury vacuum.34 kw D. It operates against a total head of 900m with an efficiency of 60%. 7.52 hp B.23 hp D.84 kw 23. The speed of the pump is 800 rpm what amount of energy must be furnished by the pump in KW?Answer: B A. 12.23 B. 204 D.45 D.Answer: A A.34 kw B. The suction line gage shows 4” Hg vacuum and the discharge gage shows 26 psi.566 kpa .45 B. 28 B. 51.51 30.33 KJ/kg. Neglect kinetic energy. Loss of head due to friction in suction pipe is 0.Answer: B A. 4 Hp D. Drawdown when pumping at rated capacity overhead storage tank. 4141 rpm D. 22 KW . A boiler feed pump receives 45 li/sec of water at 190°C and enthalpy of 839. The efficiency of the pump and motor are 64% and 84% respectively. multi-stage. The pump centerline is located 2. Calculate the specific speed of pump in rpm. 6161 rpm 32.Answer: A A.03) from a source where the water level varies two meters from high tide to low tide level.Answer: C A. 43 KW D. 191°C B. The pump discharges into a surface condenser. including friction in piping is 243 feet. It operates against a head of 952m with efficiency of 70%. what size of motor is needed to pump 1 m3/sec of water to a tank with no elevation gain? In both cases both ends of hose are at atmospheric pressure.5 Hp 33.34 31.23 D. 3 Hp C. including friction in piping is 243 feet. 41. 5. 14. 3131 rpm B. centrifugal pump delivers 900 m3/hr of sea water(SG = 1. 460 V. A double suction. The pump delivers the water into a 25. Pump is directly coupled to a 1750 rpm. 3.Answer: A A. 5151 rpm C. centrifugal deep well pump 260 gpm capacity is installed in a well 27 feet below the static water level and running at 3450 rpm. 21. What size of motor(HP) is required?Answer: B A. Calculate brake horsepower required to drive the pump if pump efficiency is 70%.31 B.8m and that in the discharge side is 3m. 165°C 29. Total discharge head developed by pump. 6. 7. 4. single stage.233 kpa 28.21 D. Using the same length of hose. 18 KW C. A submersible. A submersible. Estimate the water leaving temperature assuming that the temperature rise as due to the inefficiency of the input energyAnswer: A A. 143°C C. D. 123°C D.000 gallons capacity overhead storage tank. Hp B. Calculate the diameter of the impeller of this pump in inches if each impeller diameter developed a head of 38 ft.41 C.33 C. A pump driven by an electric motor moves 25 gal/min of water from reservoir A to reservoir B. lifting the water to a total of 245 feet. 3m above pump centerline. 3 phase. 31.6 meters above the surface of the water at high tide level. centrifugal deep well pump 260 gpm capacity is installed in a well 27 feet below the static water level. Total discharge head developed by pump. 51 KW B. Drawdown when pumping at rated capacity is 10 feet. multi-stage. Water is pumped at 1m3/sec to an elevation of 5m through a flexible hose using a 100% efficiency pump rated at 100 KW. 60 Hz motor. 082 C.54 B.0 B.16m.22m below the pump center line and reads 68. 8. A pump receives 8kg/s of water at 220 Kpa and 110°C and discharges it at 1100 kpa.14m.83. Take density of water equals 1000 kg/m3. 109 B. The total head is 9.82 D. how many stages are required?Answer: D A.343 C.126 B. 15. 5 D.76 Kpa gage. 101. Answer: A A. Neglecting any heat interaction with the surroundings and frictional heating effects. 61 D. 71 B. 98 D. 17.2 37.95 Kpa gage. Water in rural areas is often extracted from underground water source whose free surface is 60m below ground level. Compute for the power required in kilowatts. the discharge static gage is 0. The gages are located close to the pump as much as possible. A pump lifts water at a rate of 283 lps from a lake and force it into a tank 8m above the level of the water at a pressure of 137 kpa. 2 36. 5. The pump efficiency is 70%. 4 C. 9. 51 39. find how much energy does the pump consumes in KJ per hour. 11.Answer: C A. The pump pressure of water at this temperature is 2. 7. The rate of flow of water in a pump installation is 60. The diameter of the pipe is 10 cm at the inlet and 15 cm at the exit. 5. If the speed is not to exceed 1352 rpm. It is desired to deliver 5 gpm at a head of 640m in a single stage pump having specific speed not to exceed 40. 189 .34 Kpa. The pump is incapable of lifting the water higher than 10. The areas of the intake and discharge pipes are 0.34. The water is to be raised 5m above the ground by a pump.Answer: C A.041 D.104 40. 31. What is the atmospheric pressure?Answer: D A. respectively. A vacuum pump is used to drain a flooded mine shaft of 20°C water. 6. 41 C. What is the power required in kilowatts. 169 B. The intake static gage is located 1.5 C.6 kg/sec. 19 C.9 35.61m below the pump centerline and reads 344.9 D. 112 C.093 m2 and 0. 7. what is the necessary power input to the pump for a steady flow of water at the rate of 15 li/sec in KW if pump efficiency is 85%?Answer: D A. 24. 3 B.23 38.069 m2. A fuel pump is delivering 10 gallons per minute of oil with a specific gravity of 0. What is the hydraulic power in KW?Answer: A A. 15 m B. Suction gage reads 10 MM Hg vacuum and 1. 60 C. Power input is 70 kw. 681 42. Calculate the pump head in meters if suction gage is 7. 20 m D. Changes have increased the total head to 375 ft. 771 B.26 kw D.2 meters below pump centerline. 3000 rpm B. A centrifugal pump delivers 80 liters per second of water on test.000 liters per hour of water to a pressurized tank whose pressure is 280 kpa. 62 D. D. A pump delivers 500 gpm of water against a total head of 200 ft and operating at 1770 rpm. what is the torque in N-m to which the drive shaft is subjected?Answer: B A. 10 m 43.6°C water. 41. 35. A pump discharges 150 liters per second of water to a height of 75 meters. 38. The source of water is 5m below the pump. A pump with a 400 mm diameter suction and a 350 mm diameter discharge pipe is to deliver 20.16kw 44.Answer: D A. The diameter of the suction pipe is 300mm and the discharge pipe is 250mm. 781 C. Answer: A A. A centrifugal pump delivers 300.Answer: D A. 3434 rpm C. 5 m C. 791 D.000 liters per minute of 15. At what rpm should the pump be operated to achieve the new head at the same efficiency?Answer: C A.5cm below pump centerline and reads 127mm Hg vacuum and discharge gage is 45cm above the pump centerline and reads 75 kpa. 66 B. Find the total dynamic head in meters. If the efficiency is 75% and the speed of the pump is 1800 rpm.75 kw C. 64 45.75 kw B. Calculate the kw rating of the driving motor assuming the pump efficiency to be 72%. 179 41. 43. 2424 rpm .