The effects of frost thickness on the heat transfer of finned tube heat exchanger subject to the combined influence of fan types

Jeng Min Huang*, Wen Chien Hsieh, Xin Ji Ke, Chi-Chuan Wang

*Corresponding author for this work

Research output: Contribution to journalArticle

28 Scopus citations

Abstract

This study conducts a numerical study concerning the effect of frost thickness on the heat transfer performance of a four rows plate finned tube heat exchanger. Calculations are made under constant air volume and variable air volume conditions. It is found that the initial surge of heat transfer rate in the frosted finned tube heat exchanger is mainly associated with the critical radius effect rather than the surface roughness. The frost thermal conductivity plays an important role in the surge phenomenon. There is hardly any initial surge when frost thermal conductivity is below 0.1 W m-1 K-1. It is also recommended that a refrigerator should defrost when half of a single flow channel area is blocked by frost. The calculations also reveal that a centrifugal fan is recommended with a small fin-pitch heat exchanger. However, if a long term operation at a thick frost situation is unavoidable, an axial fan should be selected. There is no great difference between selection of an axial fan or centrifugal fan for a larger fin pitch heat exchanger.

Original languageEnglish
Pages (from-to)728-737
Number of pages10
JournalApplied Thermal Engineering
Volume28
Issue number7
DOIs
StatePublished - 1 May 2008

Keywords

  • Fan
  • Frost thickness
  • Plate finned tube heat exchanger

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