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ACRC Technical Report 201PDF


Title:Design Tool for Display Case Heat Exchanger Frosting and Defrosting
Author(s):Verma, P.; Bullard, C.W.; Hrnjak, P.S.
Subject(s):evaporator defrosting
Abstract:A simulation model for predicting the performance of a display case under frosting conditions has been developed. An experimentally validated heat exchanger simulation model for a secondary refrigerant was extended to simulate operation in open display cases, modeling the varying frost properties and operating conditions and their effect on heat exchanger performance. A separate model based on a few simplifying assumptions has been developed to simulate the defrosting, predict the time required to melt the frost mass (existing at the end of frosting cycle) and compressor and fan power requirements for an entire day operation of a display case. Two design strategies for reducing defrost frequency and overall energy consumption of open supermarket display cases were evaluated relative to the baseline (variable air flow as a consequence of fan characteristics) operation: constant air flow operation; and fin staging. A preliminary analysis of a flat-tube-plain-fin heat exchanger with discontinuous fins was also conducted A simple comparison of heat transfer performance at dry surface conditions shows that all the designs considered are better than an existing display case round-tube-plain-fin heat exchanger.
Issue Date:2002-10
Publisher:Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.
Series/Report:Air Conditioning and Refrigeration Center TR-201
Genre:Technical Report
Sponsor:Air Conditioning and Refrigeration Project 119
Date Available in IDEALS:2009-06-04

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