| Three types of phenomenological models, viz. "superposition," "asymptotic," and "enhancement," used for calculating convective vaporization coefficients, are described. Correlations based on these models, which apply to in-tube or tube bank situations, are critically reviewed. The asymptotic model is proposed as a generalized model for both, in-tube and tube bank situations. Tube bank data are reported for R-11, R-123, and R-134a at saturation temperatures of 4.4 C and 26.7 C. The tube banks have staggered bundle layout and a pitch-to-diameter ratio of 1.25. The tubes tested include GEWA-SE, Turbo-B and integral finned tubes (26 fins/inch). The data span heat fluxes of 15 to 47 kW/m... |
