This paper focuses on defrost aspects of display case operation when indirectly refrigerated. The paper provides experimental results of defrost cycles in the same display case in three modes: (a) electrical resistance heater (after 24 h of operation in the conventional DX mode), (b) warm liquid, and (c) electric heater. Defrosts (b) and (c) were performed after 24 h of operation in the secondary loop mode. This paper discusses the change of operating parameters in defrost, identifies critical locations in the display case, and suggests control variables for defrost. The data presented analyze the effects of the warm liquid flow rate and temperature on defrost. It is shown that an increase in the warm fluid temperature and fluid velocity speeds up the defrost of the heat exchanger but does not affect defrost of other parts of the display case (air ducts, drip pan, etc.).

Units: SI