Frost formation and defrosting on tube-array evaporators in a fluidized bed and an impinging jet

T. Aihara, H. Gakumasawa, S. Maruyama, M. Hongoh

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Frost formation on evaporators and the resultant choking of the evaporators are perplexing problems in heat pump systems using ambient air as a heat source. In the present study, heat and mass transfer, frost formation, and defrosting of single-row cooled tubes were investigated experimentally in a uniform humid air flow, an impinging air jet, and a fluidized bed with a multislit distributor and static bed height of 10 mm, respectively. Because of frost formation, the heat transfer performance for the impinging jet decreased with time. With Teflon-coated tubes in the fluidized bed using glass beads 0.92 mm in diameter, it was found that frost-free running is possible under comparatively wide conditions of heat flux and superficial velocity, and that the heat transfer performance is about five times as large as that for uniform airflow.

Original languageEnglish
Pages (from-to)65-71
Number of pages7
JournalExperimental Thermal and Fluid Science
Volume2
Issue number1
DOIs
Publication statusPublished - 1989 Jan

Keywords

  • fluidized beds
  • heat exchangers
  • heat transfer augmentation
  • jets
  • mass transfer
  • phase-change phenomena

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Nuclear Energy and Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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