Performance of a showcase refrigeration system with multi-evaporator during on–off cycling and hot-gas bypass defrost

During the defrosting process, the temperature in the cabinet of a showcase becomes higher than the set point. This phenomenon is undesirable for foods or products stored. It is essential to develop an efficient defrosting method to prevent large temperature fluctuations. In the present study, the performance of the showcase refrigeration system with three evaporators was measured during on–off cycling and hot-gas bypass defrost. Based on the test results, the effects of off-period in the on–off cycling and EEV opening in the hot-gas bypass defrosting cycle on the performance of showcase system were analyzed. In addition, the operating characteristics of the hot-gas bypass defrosting cycle were compared with those of the on–off cycling. The hot-gas bypass defrosting method showed higher refrigerating capacity and less temperature fluctuations than the on–off cycling under frosting/defrosting conditions even though it required more compressor power.