A falling film evaporator is attracting attention to reduce the refrigerant filling amount. For heat transferenhancement of the falling film evaporation, forming and keeping a thin liquid film on the heat transfer surfaceare important. In this study, thermal spray coating was applied on a low finned tube. The contribution ofnucleate boiling in the film evaporation heat transfer of HFO1233zd(E) was evaluated from the comparison inthe experimental results of pool boiling using the same test section. The tube length was 50 mm and thediameter at the top of the fins was 19.05 mm. The liquid film flow rate was fixed at 0.033 kg×m~(–1)×s~(–1) and theheat flux was varied from 10 to 85 kW×m~(-2). As a result, it was shown that the enhancement factor by thecoating was up to 2.0 for falling film evaporation and was higher than the pool boiling.
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