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WARM-LIQUID DEFROST FOR COMMERCIAL FOOD DISPLAY CASES: EXPERIMENTAL INVESTIGATION AT 32.2 DEGREES C CONDENSING
Citation:
Gage*, C L. AND G. S. Kazachki. WARM-LIQUID DEFROST FOR COMMERCIAL FOOD DISPLAY CASES: EXPERIMENTAL INVESTIGATION AT 32.2 DEGREES C CONDENSING. Presented at Illinois Conference on Commercial Refrigeration, Urbana, IL, 7/22-23/02.
Description:
The paper gives results of an experimental investigation at 32.2 C condensing of warm-liquid defrost for commercial food display cases. A refrigeration test rig with two open cases and two reach-in cases was tested using warm-liquid defrost (WLD) at -34.4 C evaporating, 32.2 C condensing, and 4.4 K subcooling below the condensing temperature. Results were compared to electric defrost (ED) at the same conditions. For all cases, WLD at 32.2 C condensing performed as well as ED (e.g., coils reached comparable temperatures at the end of defrost). For the open cases where defrost times were comparable, WLD causes a 1 K smaller rise in product temperature than is observed with ED. For the reach-in cases, defrost time for the WLD was 1 hour, compared to 35 minutes for ED. As a result of the longer defrost time, the product temperature was higher by 1.7 K with WLD than with ED. Increasing the flow rate of the liquid would shorten the defrost time and improve the product conditions.