Elementary Principles 333 - 8.74(cont'd Energy balance on...

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8-54 8.74 (cont’d) Energy balance on cooler-reheater References : Same as Fig. 8.4-2 [including H 2 O(l, 32 o F)] Substance in in ˆ mH ± out out ˆ ± Fresh air feed 10.93 45.5 DA m in lb dry air/min m ± Recirculated air feed 65.57 26.2 air m ˆ in Btu/lb dry air H Delivered air 76.5 21.4 2 HO ( l ) m in lb /min m ± Condensed water (49 o F) 0.165 17.0 2 ( l ) m ˆ in Btu/lb H ii out in 575.3 Btu 60 min 1 ton cooling ˆˆ 2.9 tons min 1 h -12,000 Btu/h QH m H m H =Δ = = = ∑∑ ± ± ±± Percent saved by recirculating = (9.1 tons 2.9 tons) 100% 68% 9.1 tons ×= Once the system reaches steady state, most of the air passing through the conditioner is cooler than the outside air, and (more importantly) much less water must be condensed (only the water in the fresh feed). c. Total recirculation could eventually lead to an unhealthy depletion of oxygen and buildup
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This note was uploaded on 02/27/2012 for the course CHEMICAL E 312 taught by Professor Cheung during the Fall '11 term at The University of Akron.

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