Defrost issues in indirectly refrigerated display cases

P. S. Hrnjak, Y. Mao, Kenneth Elovitz, John Behr

Research output: Contribution to journalConference articlepeer-review


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.).

Original languageEnglish (US)
Pages (from-to)466-472
Number of pages7
JournalASHRAE Transactions
Volume107 PART 2
StatePublished - 2001
Event2001 ASHRAE Annual Meeting - Cincinnati, OH, United States
Duration: Jun 24 2001Jun 27 2001

ASJC Scopus subject areas

  • Building and Construction
  • Mechanical Engineering


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