In an air-conditioning system 30 m3/min of fresh out-door air is introduced at 430C dry-bulb temperature and 30% relative humidity. The remaining air is re-circulated from the room maintained at 250C dry-bulb temperature and 50% RH. The by-pass factor of the cooling coil is 0.15 and apparatus dew point is 11.80C. RSH = 100 kW and RLH = 15kW. Determine (i) humidity ratios for outdoor and room condition, (ii) OASH and OALH, (iii) ERSH and ERLH, (iv) supply air temperature, (v) supply air volume flow rate using ERSH and (vi) temperature at inlet to cooling coil by assuming the density of outdoor air and recirculated air to be the same.
Given that saturation pressures of water at 250C and 430C are 3.1693 kPa and 8.6495 kPa respectively. Show that process on psychrometric chart schematically. Standard atmospheric pressure = 1.01325 bar.