BOILING HEAT-TRANSFER WITH BINARY-MIXTURES - PART-II - FLOW BOILING IN PLAIN TUBES

Flow boiling heat transfer with pure fluids comprises convective and n ucleate boiling components. In flow boiling of binary mixtures, in add ition to the suppression effects present in pool boiling, the presence of flow further modifies the nucleate boiling characteristics. In the present work, the flow boiling correlation by Kandlikar (1990, 1991b) for pure fluids is used as the starting point, and the mixture effect s derived in Part I (Kandlikar, 1998) of this paper are incorporated T hree regions are defined on the basis of a volatility parameter, V-1 = (c(p)/Delta h(LG))(kappa/D-12)(1/2)\(y(1) - x(1))dT/dx(1)\. They are: region I-near azeotropic, region II-moderate diffusion-induced suppre ssion, and region III-severe diffusion-induced suppression. The result ing correlation is able to correlate over 2500 data points within 8.3 to 13.3 percent mean deviation for each data set. Furthermore, the alp ha-x trend is represented well for R-12/R-22, R-22/R-114, R-22/R-152a, R-500, and R-132a/R-123 systems. Electrically heated stainless steel test sections as well as fluid-heated copper rest sections are both co vered under this correlation.