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Effects of surface coating and water retention on frost formation in microchannel evaporators (ASHRAE RP-1589).

Author(s) : MOALLEM E., HONG T., CREMASCHI L., et al.

Type of article: Article

Summary

This study experimentally investigated frost growth on louvered folded fins in outdoor microchannel heat exchangers when used in air-source heat pump systems. The effects of five surface coatings on the thermal and hydraulic performance of the microchannel heat exchangers under frosting conditions were studied. The overall aim was to provide some guidelines about frosting behavior of microchannel heat exchangers with hydrophilic and hydrophobic coatings. The approach taken was to perform laboratory experiments on small-scale coils and several sample fins that were cut out from commercially available heat exchangers. The sample fins were tested in controlled laboratory conditions that replicated those in actual heat pump systems in the winter season. A better estimation of the fin surface temperature was achieved with the methodology developed in the present study. The experimental value of air pressure drop across the coils, time of frost–defrost cycles, and heat transfer rates were recorded for heat exchangers operating in actual transient frosting conditions. Data showed that the frosting time and frost growth rates depended mainly on the local fin surface temperature. Five surface coatings were investigated, and the data show that the hydrophobic coating had slightly lower frosting performance after a few defrost cycles with respect to hydrophilic surface coating.

Details

  • Original title: Effects of surface coating and water retention on frost formation in microchannel evaporators (ASHRAE RP-1589).
  • Record ID : 30008852
  • Languages: English
  • Source: HVAC&R Research - vol. 19 - n. 4
  • Publication date: 2013/05
  • DOI: http://dx.doi.org/10.1080/10789669.2013.781056

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