Question

(10 pts) Six-thousand cubic feet per minutes (C.F.M.) of atmospheric air at 28°C (dry bulb) having a wet bulb temperature of 23°C is to be cooled in an air conditioning system. The air conditioning system lowers the dry bulb temperature of the air to 20° C. Cooling with dehumidification is accomplished using chilled water loop. The chilled water enters the loop at 5°C at a rate of 280 kg/min and experience a 5°C temperature increase. The atmospheric pressure is 1 atm (101.3 kPa) with a density of 1.18 kg/m3. Water has a specific heat of 4.18 kJ/kg-K. (a) Determine the relative humidity and specific humidity of the incoming air, as well as its dew point temperature. You may use a psychometric chart. (b) Determine the temperature (°C) of the air leaving the air-to-chilled water heat exchanger along with the rate of dehumidification (condensation) in kg/hr. (c) Determine the amount of heating required to raise the conditioned air leaving the air-to-chilled water heat exchanger back up to 20°C. (d) Determine the final relative humidity and specific humidity of conditioned air at 20°C, as well as its dew point temperature.