ME 3333 Chapter : Homework 12 Solutions
Document Summary
An air-conditioner in the airport of timbuktu runs a cooling system using r-410a with a high pressure of 1500 kpa and a low pressure of 200 kpa. It should cool the desert air at 45oc down to 15oc. Pcond = p2 = p3 = 1500 kpa. State 1: t1 = -37. 0oc, h1 = 264. 3 kj/kg, s1 = 1. 119 kj/kg-k. State 2: p2 = 1500 kpa, s2 = s1: t2 = 53. 8oc, h2 = 322 kj/kg wc = h2 - h1 = 322 264. 3 = 57. 7 kj/kg. State 3-4: p4 = p3, x3 = 0: t3 = 21. 4oc, h4 = h3 = 91. 55 kj/kg ql = h1 - h4 = 264. 3 91. 55 = 172. 75 kj/kg. The heat rejection from 2-3 to ambient at 45oc has t3 = 21. 4oc not hot enough so the system will not work. The high pressure must be much higher so t3 > 45oc.
