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  • Falling film evaporation ex...
    Ouyang, Xin-Ping; Sun, Ke

    International journal of refrigeration, February 2022, 2022-02-00, 20220201, Volume: 134
    Journal Article

    •"The Wilson-Gnielinski-Heat Flux Correction Method" is proposed.•The enhancement rates are 2.53 and 2.68 for the tubes with 19 and 25 mm diameter.•The heat transfer performance of falling film evaporation of R1234(E) is studied.•When the heat flux is 30 kWm−2, the Refthreshold of R1234ze (E) is 669. For two kinds of specially made enhanced tubes with outer diameters of 19 and 25 mm, the falling film evaporation experiment was carried out by using environmental refrigerant R1234ze (E) under the experimental condition that the water velocity in the tube was controlled from 1 to 3.5 ms−1. "The Wilson-Gnielinski Separation Method" and "The Wilson-Gnielinski-Heat Flux Correction Method" were used to process the experimental data. The comparative analysis showed that when the heat fluxes of all the test points outside the tube were constant, the results of two calculation methods were almost the same. When the heat fluxes of all the test points outside the tube were fluctuant, the results of two calculation methods were different and the heat flux correction method should be applied to reduce the error. The enhanced tube with outer diameter of 19 mm was used to investigate the heat transfer performance of falling film evaporation, with spray density ranging from 0.03 to 0.1 kgm−1 s−1, heat flux ranging from 15 to 45 kWm−2 and evaporation temperature ranging from 0 to 25 °C. And the enhancement rate inside the tube was obtained by using the heat flux correction method. Finally, the variation trends of the overall heat transfer coefficient and the outside tube heat transfer coefficient under different working conditions were both obtained experimentally and analyzed theoretically.