Evaporating heat transfer characteristics of R744 -relation between the evaporating heat transfer and flow pattern of refrigerant with oil

Masafumi Katsuta, Shinya Kishi, Naoyuki Miyachi, Takahiro Oshiro, Ryouichi Takai

    Research output: Chapter in Book/Report/Conference proceedingConference contribution

    Abstract

    This paper describes evaporating heat transfer characteristics of a refrigeration cycle. Using R744 as working refrigerant, the effect of the oil mixing rate on the thermal and hydraulic characteristics were investigated. The main test section was a stainless tube an ID of 3.0 mm and the length of 500 mm, which was directly heated by electricity from an electric pole. Further, in order to visualize the flow pattern of the mixture of refrigerant and oil, we placed behind the evaporator sight glass made of acrylic block of 3.0 mm in ID and 135mm in length. Throughout experiments, it was recognized that oil was a significant factor of the heat transfer deterioration and of the increase of pressure drop. In addition, it was observed that the transition of the flow pattern was accelerated as oil concentration increases. Finally, it was concluded that the transition of the flow pattern was influenced by the mass flux and the oil concentration.

    Original languageEnglish
    Title of host publication4th Asian Conference on Refrigeration and Air-Conditioning, ACRA 2009
    PublisherNational Taipei University of Technology
    Pages305-310
    Number of pages6
    ISBN (Print)9868509610, 9789868509610
    Publication statusPublished - 2009
    Event4th Asian Conference on Refrigeration and Air-Conditioning, ACRA 2009 - Taipei
    Duration: 2009 May 202009 May 22

    Other

    Other4th Asian Conference on Refrigeration and Air-Conditioning, ACRA 2009
    CityTaipei
    Period09/5/2009/5/22

    Keywords

    • Dryout
    • Flow pattern
    • Heat transfer
    • Lubricant
    • Pressure drop

    ASJC Scopus subject areas

    • Chemical Engineering (miscellaneous)

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