Vertical falling film evaporation of pure refrigerant HCFC123 in a plate-fin heat exchanger

Junichi Ohara, Shigeru Koyama

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

    Abstract

    The characteristics of heat transfer and flow patterns are investigated experimentally for the vertical falling film evaporation of pure refrigerant HCFC123 in a rectangular minichannels consisting of offset strip fins. The refrigerant liquid is uniformly supplied to the channel through a distributor. The liquid flowing down vertically is heated electrically from the rear wall of the channel and evaporated. To observe the flow patterns during the evaporation process directly, a transparent vinyl chloride resin plate is placed as the front wall. The experimental parameters are as follows: the mass velocity G = 28∼70 kg/(m2s), the heat flux q = 20∼50 kW/m2 and the pressure P ≈ 100 kPa. It is clarified that the heat transfer coefficient α depends on G and q in the region of vapor quality × ≥ 0.3 while there is little influence of G and q in the region × ≤ 0.3. From the direct observation using a high speed video camera and a digital still camera, flow patterns are classified into five types. Then the empirical correlation equations for evaporation heat transfer coefficient on a vertical falling film plate fin evaporator with minichannels are proposed. From the physical model to evaluate the heat transfer coefficient of the minichannel surface with fins, the characteristics of fin efficiency is clarified that the average value of fin efficiency is about 0.6 and the distributive characteristics of fin efficiency is roughly inverse of heat transfer coefficient characteristics.

    Original languageEnglish
    Title of host publicationASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013
    DOIs
    Publication statusPublished - 2013
    EventASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013 - Sapporo, Japan
    Duration: Jun 16 2013Jun 19 2013

    Publication series

    NameASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013

    Other

    OtherASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013
    CountryJapan
    CitySapporo
    Period6/16/136/19/13

    All Science Journal Classification (ASJC) codes

    • Fluid Flow and Transfer Processes
    • Process Chemistry and Technology
    • Modelling and Simulation

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