A summary of a comprehensive experimental study on flow boiling heat transfer is presented for five refrigerants (R134a, R123, R402A, R404A, and R502) evaporating inside plain, horizontal, copper tube test sections. The test data were obtained for both 12.00 mm and 10.92 mm diameters using hot water as the heating source. Besides confirming known trends in flow boiling heat transfer data as a function of test variables, it was also proven that the heat flux level at the dryout point at the top of the tube in annular flow has a very significant downstream effect on heat transfer coefficients in the annular flow regime with partial dryout.

Issue Section:
Boiling and Condensation
Keywords:
Evaporation, Flow Visualization, Multiphase Flows
Topics:
Boiling, Evaporation, Flow (Dynamics), Heat transfer, Refrigerants, Copper, Flow visualization, Heat flux, Heat transfer coefficients, Heating, Hot water, Multiphase flow
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