1.
A cylindrical cylindrical flash tank mounted with its axis horizontal is used used to separate liquid ammonia from ammonia vapor. The ammonia vapor bubbles through the liquid with 70 m 3/min leaving the disengaging surface. The disengaging rate is limited to 60 m/min and the liquid level is to operate with the liquid level one-third of the diameter from the top. Determine the diameter if the tank is 1.5 m long. a. 830 mm C. 860 mm b. 730 mm D. 760 mm
2. The sum for the resistance for the outside wall of a house is 8 K-m2/W.For a temperature difference of 25 oC across the wall and a total surface area of 150 m2, determine the heat flow through the wall. a. 468.75 W b. 159.75 W c. 298.75 W d. 348.75 W 3. Determine the compressor work of a Brayton cycle if its pressure ratio is 8 and the initial temperature is 32 oC. a) 248.67 kJ/kg b) 278.47 kJ/kg c) 284.67 kJ/kg d) 267.84 kJ/kg 4. The flow of a river of 21.25 21 .25 m3/s produce a total brake power of 5,400 KW. It is proposed to install two turbines, one of which is twice the capacity of the other. The efficiency and specific speed of both units are assumed to be 85% and 70 rpm, respectively. respect ively. Determine the head of the turbine. a. 40.475 m b. b. 30.475 m c. 20.475 m d. 50.475 m 5. A turbine has a peripheral coefficient of 0 .6. If the turbine head is 60 meters, find the runner diameter of the turbine at 450 rpm speed. a. 788 mm b. 840 mm c. 873 mm d. 920 mm 6. A flashed steam geothermal power plant is located where underground hot water is available as saturated liquid at 700 kPa, the well head pressure is 600 kPa. The flashed steam enters the turbine at 500 kPa and expands to 1 5kPa, when it is condensed. The flow rate from the well is 29.6 kg/s. Determine the power produced in kW. Properties: @ 0.70 MPaa, hf = 697 .22 kJ/kg; @ 500 KPaa, hf = 640.23 kJ/kg, hfg = 2108.5 kJ/kg; @15 kPaa, h = 2211.1 kJ/kg. a) 430.16 kW b) 403.16 kW c) 416.30 kW d) 360.41 kW 7. A 100 TR system is used to produce chilled water from 22 oC to 2 oC. Determine the mass flow rate of chilled chilled water? a) 4.2 kg/s b) 3.2 kg/s c) 2.4 kg/s d) 2.4 kg/min 8. A 90 TR system has a compressor com pressor input of 0.97 kW per TR and COP of 5. Determine the efficiency of the compressor. a) 72.5 % b) 75.2 % c) 74.5 % d) 73.5 % 9. The gravimetric analysis of the dry ex haust gas from an internal combustion engine is as follows: CO2 = 20 %; O2 = 5 %; N2 = 75 %. Det ermine the specific heat gas constant in kJ/kg -oK. a) 0.2780 b) 0.2735 c) 0.2652 d) 2.0776 10. An ideal dual combustion cycle operates on 0.45 kg of air. At the beg inning of compression, the air is 97 kPaa, 43 oC. Let rp = 1.5, rc = 1.6, and rk = 11. Determine the thermal efficiency. a) 58.7 % b) 57.8 % c) 48.7 % d) 68.7 % 11. A horizontal pipe carries oil with a specific gravity of 0.83. If two pressure gauges along the pipe read 515 kPa and 430 kPa, respectively. Determine the head loss between the two gauges. a) 10.44 m b) 14.40 m c) 14.04 m d) 40.14 m 12. The percent rating of water tube t ube boiler is 200 %, factor of evaporation is 1.10, and heating surface is 400 ft2. Determine the rate of evaporation, in kg/hr a) 1831 b) 1831 c) 1138 d) 1813
13. Determine the mole fraction of the helium in a mixture of 45 % helium and 55 % nitrogen by mass analysis. a) 14.84 % b) 85.16 % c) 18.44 % d) 81.56 % 14. For an electric gener ator running at 5 rps and 60 Hz, find the number of poles. a) 24 poles b) 18 poles c) 8 poles d) 20 poles 15. A boiler uses 2500 kg of coal per hour and air required for combustion is 16 kg per kg coal. If ash loss is 10 %, determine the mass m ass of gas entering the chimney. a) 43 250 kg/hr b) 42 250 kg/hr c) 44 250 kg/hr d) 41 250 kg/hr 16. Determine the partial pressure of CO2 for the following analysis of gas mixture by weight at 101.325 kPaa and 20 oC: CO2 = 30 % and N2 = 70 %. a) 21.717 kPaa b) 27.171 27.171 kPaa c) 17.712 kPaa d) 17.172 kPaa 17. A boiler feed pump receives 45 lps of water at 190 oC and enthalpy of 839.3 kJ/kg. It operates against a total head of 952 m w ith efficiency of 70 %. Calculate the enthalpy leaving the pump, in kJ/kg. a) 878.10 b) 875.56 c) 852.6 d)725.6 18. A water-tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3, boiler rating is 200 %, boiler e fficiency is 85 %, heating surface is 0.91 m2/Bo Hp and the heating value of the fuel is 18400 kJ/kg. Find the approximate heating surface of the boiler, in m2. a) 45 b) 35 c) 28 d) 38 19. A 500 kW Diesel e ngine operates at 101.3 kPaa and 27 oC in Calamba City. If the engine will operates in Baguio City having 93 kPaa and 23 oC, what new brake power will be developed if mechanical efficiency is 85 %. a) 455.96 kW b) 549.10 kW c) 954.1 kW d) 495.1 kW 20. An air-vapor mixture has a DB tem perature of 30 oC and a humidity ratio of 0.015 kg/kg d.a. Calculate the enthalpy. a) 68.527 kJ/kg d.a. b) 78.527 kJ/kg d.a. c) 58.527 kJ/kg d.a. d) 88.527 kJ/kg d.a. 21. Calculate the moisture content of moist air at 20 oC DB, 15 oC WB, and 95 kPa barometric pressure. Let the saturation pressure of wate r at 15 oC equals e quals to 1.7057 kPaa and at 20 oC is 2.339 kPaa. a) 0.00923 kg/kg d.a. d.a. b) 0.00293 kg/kg d.a. d.a. c) 0.00392 kg/kg d.a. d.a. d) 0.00239 kg/kg d.a. 22. 2.5 m3/s of humid air at a state of 28°C DB, 21 WB and 101.325 Kpaa flow across a cooler c oil and leaves at 12.5°C DB and 0.0083 kg vapor per kg dry air. If the apparatus dew point (ADP) is 8.5, compute for the contact factor (CF). a) 0.835 b. 0.795 c. 0.579 d. 0.306 23. An evaporator has a temperature of 3 C with entrance enthalpy of 352.75 kJ/kg. At 3 C, hf = 319.56 kJ/kg and hg = 642.45 kJ/ kg. Find the quality after expansion. a) 28.10 % b) 12.08 % c) 10.28 % d) 18.02 % 24. An ideal dual combustion cycle operates on 0.45 kg of air. At the beg inning of compression, the air is 97 kPaa, 43 oC. Let rp = 1.5, rc = 1.6, and rk = 11. Determine the percent clearance. a) 10 % b) 11 % c) 9 % 12 % 25. A boiler operates at 82.5 % efficiency while the mass of steam generated is 408 200 kg in 5 hours. The enthalpy of steam is 3187 kJ/kg and feed is 604.83 kJ/kg while the fuel used for boiler has a heating value of 32 567.85 kJ/ kg. Find the mass of fuel needed per day in metric tons. a) 188.3 b) 183.8 c) 138.8 d) 318.8
26. A 15 kW motor running at 350 rpm is used to drive pump. If speed will be changed to 370 rpm, what is the increase in power? a) 2.72 kW b) 7.22 kW c) 3.73 kW kW d) 7.33 kW 27. Determine the heating value of a ce rtain fuel with a SG = 0.997. 0 .997. a) 42 975 kJ/kg b) 42 597 kJ/kg c) 42 795 kJ/kg d) 42 579 kJ/kg 28. A condensate pump at sea level takes water from a surface condenser where the vacuum is 15 in. of mercury. The friction and turbulence in the piping in the condenser hot well and the pump suction flange is assumed to be 6.5 ft. if the condensate pump to be installed has a required head of 9 ft, what would be the minimum height of water level in the hot well that must be maintained above the centerline of the pump to avoid cavitations? 2.5 ft C. 18 ft 15.5 ft D. 5.5 ft 29. What is the velocity of sound 150°F (66°C) air at a standard pressure? Note: density of air @ 150°F is 0.064 lbm/ft3. 1215 ft/s C. 2345 ft/s 3245 ft/s D. 4321 ft/s 30. To what weight will 68°F ethyl alcohol rise in a 0.005 inch internal diameter glass capillary tube? The density of alcohol is 49 lbm/ft3. Where: β = 0° = angle of contact angle and surface tension σ = 0.00156 lbm/ft @ 68°F. 0.3056 ft C. 0.4312 ft 0.2504 ft D. 0.2432 ft
