In a vessel at 320 K and 101.3 kPa, the percentage relative humidity of moist air is 60. At 320 K the pressure of the saturated water vapour is 10.55 kPa, calculate:

(a) In a vessel at 320K and 101.3kPa, the percentage relative humidity of moist air is 60 . At 320K the pressure of the saturated water vapour is 10.55kPa, calculate: (b) The humid air of a given initial condition as shown in (a) is cooled to temperature 290K by a cooling coil. Calculate the amount of water removed from the air in kgs1. The flow rate of dry air is 7kgs1 which remains constant throughout the conditioning system. The dew point of the moist air (320K,RH=60%) is 311K, the pressure of the saturated water vapour 1.97kPa at 290K. [6 MARKS] (c) If the humid air of a given initial condition as that described in (a) flows countercurrently to the water through a thermally insulated humidification column, calculate the humidity of the moist air at saturation temperature 313K, taking into account that: The gas is completely saturated at the top of the column; The temperature of the water at the top and bottom of the column and of the gas at the top approach the adiabatic saturation temperature 313K; The latent heat of water is 2500kJkg1. [4 MARKS] (d) Describe the classification of a mechanical draught cooling tower and its advantages and disadvantages compared with a natural draught cooling tower