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Heat Transfer Enhancement and Pressure Drop for R417A Flow Boiling in Internally Grooved Tubes

An experimental investigation of evaporation for R417A in horizontal smooth and internally grooved tubes has been carried out. Based on the experimental results, performance of heat transfer and pressure drop for R417A flow boiling in different tubes was analyzed, and the influences of micro-fin parameters and mass fluxes on heat transfer enhancement factors and pressure drops were discussed. The results indicate: the enhancement effect of Tube III having the narrower spirally grooves excels than Tube II, and the enhancement factors increase with the increasing mass flux. R417A produces slightly bigger pressure drops in Tube II than Tube III, and the pressure drops increase with the increasing mass flux and vapor quality, this increase is more obvious in internally grooved tubes.