Two-phase heat transfer characteristics for R-22/R-407C in a 6.5-mm smooth tube

Abstract

Two-phase friction and heat transfer characteristics for R-22/R-407C inside a 6.5-mm smooth tube are reported in this study, The hear transfer results for G = 100 and 400 kg/m(2) s were reported in the present study, and the adiabatic frictional pressure drop was recorded in the range of 100 to 700 kg/m(2) s, It is found that the development of flow pattern for R-407C Falls behind R-22. This may explain the lower pressure drops for R-407C. The major heat transfer mechanism at low mass flux is nucleate boiling, and virtually becomes the convective evaporation as mass flux increase to G = 400 krg/m(2) s, Meanwhile, the reduction of heat transfer coefficients for R-407C mixtures are especially profound at low mass flux, and The reduction of heat transfer coefficient decreases with the increase of mass flux. (C) 1997 by Elsevier Science Inc.