WEBC08 06/04/2015 22:38:26 Page 485 (b) If the vent switch

Chapter 8, Problem 8.88

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WEBC08 06/04/2015 22:38:26 Page 485 (b) If the vent switch is set to the closed position (as it normally would be), inside air would be recirculated through the air conditioner as shown in the following diagram. REHEATER Delivered air 55F Exhaust 75F hr = 40% COOLER AIR CONDITIONER 75F Recirculated room air hr = 40% Outside air 87F hr = 80% LAB Condensed water Q (tons) The recycle ratio (ft3 recirculated/ft3 exhausted) is 6:1. 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 Part (a). What percentage of the cooling load on the air conditioner is saved by recirculating the air? Explain in your own words why the cooling rate is lower when room air is recirculated instead of bringing all the air in from the outside. (c) An even lower cooling load would be required if all of the air passing through the conditioner were recirculated rather than just 6/7 of it, thereby eliminating the need for outside air and exhaust. Why would this be a bad idea? (Hint: Think about the people working in the laboratory.)