Abstract
Boiling heat transfer coefficient was measured for refrigerant liquid with oil contained. The liquid flowed in film on a horizontal heating surface with the vapor flowing in the upper part of a rectangular duct at different liquid flow rates, vapor flow rates, heat fluxes and oil mass fractions. Whenever the refrigerant contained the oil, the flow with foaming action was observed. The heat transfer coefficient was always decreased with increasing oil mass fraction. In order to investigate the influence of oil on the heat transfer, a dimensional correlation of the heat transfer coefficient was tentatively developed, as the sum of contributions by nucleate boiling and forced convection to the heat transfer. Based on this correlation, it was found that the reduction of the heat transfer coefficient with increasing oil mass fraction, especially until the oil mass fraction up to 20 percent, was attributed mainly to the rapid reduction of contribution by the nucleate boiling, and that the ratio of the heat transfer rate by the nucleate boiling to the total rate was decreased as the oil mass fraction was increased, because of much less reduction of the heat transfer rate by the forced convection
