• University of Castilla la Mancha

• ME 322

AIR CONDITIONING 1. When 100 kg/min of outside air at 32°C dry bulb and 200 kg/min recirculated air at 22°C dry bulb are mixed with an air conditioning system, the resulting dry bulb temperature will be: a. 25.33°C b. 35.44°C c. 46.33°C d. 26.88°C 2. The amount of water carried by air in a cooling tower is 15 lb/min. The change in humidity ratio in outlet and inlet is 0.025 lb/lb. Determine the volume flow of air needed if specific volume is 15 ft3 /lb. a. 6000 ft3 /min b. 7800 ft3 /min c. 7500 ft3 /min d. 5000 ft3 /min 3. The change of enthalpy of air in a cooling tower is 35 Btu/lb and the mass flow of air is 453.17 lb/min. Water enters the tower at the rate of 50 gpm and 115 °F. Determine the exit temperature. a. 45°F b. 55°F c. 65°F d. 77°F 4. The change of enthalpy in air conditioning unit is 10 Btu/lb. The mass of supply air is 150,000 lb/hr. What is the conditioner capacity? a. 125 TR b. 100 TR c. 150 TR d. 200 TR 5. Recirculated air of 8 kg/s with 53 kJ/kg enthalpy and outside air of 2 kg/s with 90 kJ/kg enthalpy enters the conditioning unit. Determine the air conditioning capacity if supply enthalpy to conditioned space is 42 kJ/kg. a. 154 kW b. 164 kW c. 174 kW d. 184 kW 6. Outside air of an air conditioning system is 25% of recirculated air. Determine the mass of outside air if mass of supply air is 15 kg/s. a. 1 kg/s b. 2 kg/s c. 3 kg/s d. 4 kg/s 7. The sensible heat load and latent heat load in an air conditioning system is 120 kW and 47 kW, respectively. What is the sensible heat factor? a. 65.34% b. 29.45% c. 76.54% d. 71.86% 8. The total heat load and latent heat load of theater is 150 kW and 60 kW, respectively. Supply air is at 15°C and has a mass of 9 kg/s. Determine the temperature to be maintained in the theater. a. 20°C b. 25°C c. 30°C d. 35°C 9. A cooling tower has an efficiency of 65%. Water enters the tower at 55°C. The wet bulb temperature of surrounding air is 27°C. What is the temperature of water leaving the tower? a. 36.8°C b. 44.5°C c. 46.9°C d. 30.4°C 10. The change of temperature entering the cooling tower and wet bulb temperature of surrounding air is 25°C and efficiency is 65%. If mass of water leaving the tower is 10 kg/s, determine the heat carried by air. a. 720 kW b. 540 kW c. 680 kW d. 700 kW 11. The approach and efficiency of cooling tower is 10°C and 60%, respectively. If temperature of water leaving the tower is 37°C, what is the temperature of water entering? a. 46°C b. 52°C c. 68°C d. 48°C 12. A cooling tower is used to cool a jacket water loss from the engine. The heat generated by fuel is 2500 kW and cooling loss is 30%. If temperature range of the tower is 15°C.