On an uncomfortable summer day, the air is at 87 F and 60% relative humidity. A laboratory air conditioner is to deliver 1.0 x 103 ft3/min of air at 55 F in order to maintain the interior air at an average temperature of 75F and a relative humidity of 40%. If the vent switch is set to the "closed" position (as it normally would be), inside air would be recirculated throgh the air conditioner as shown in the following diagram. Recirculated room air, 75F h, = 40% Exhuast 75F h = 40% AIR CONDITIONER Delivered air REHEATER (tons) CF LAB 75F h, = 40% Outside air COOLER A 'F h, = B % Condensed water Assume A = 87 F, B = 60%, C = 55 F. The recycle ratio (ft3 recirculated/ft? exhausted) is 2:1. Calculate the condensation rate and the overall cooling requirement in tons if conditioned air is delivered at the same rate, temperature, and relative humidity as in the first part. What percentage of the cooling load on the air conditioner is saved by recirculating the air? Condensation rate: i 0.3376 Ibm/min Cooling load: 4.7622 tons Percentage savings: i 33.819 %