Chapter 1 Basics of Heat Transfer1-131A refrigerator consumes 600 W of power when operating, and its motor remains on for 5 min and then off for 15 min periodically. The average thermal conductivity of the refrigerator walls and the annual cost of operating this refrigerator are to be determined. Assumptions1Quasi-steady operating conditions exist.2The inner and outer surface temperatures of the refrigerator remain constant. AnalysisThe total surface area of the refrigerator where heat transfer takes place is Atotal2m=×+×+×=218 1218 0812 08912(..) (..).Since the refrigerator has a COP of 2.5, the rate of heat removal from the refrigerated space, which is equal to the rate of heat gain in steady operation, is &&QWe=×=COPW)W6002 51500But the refrigerator operates a quarter of the time (5 min on, 15 min off). Therefore, the average rate of
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This note was uploaded on 01/14/2012 for the course PHY 4803 taught by Professor Dr.danielarenas during the Fall '10 term at UNF.