INFLUENCE OF THE HEAT-FLUX IN MIXTURE BOILING - EXPERIMENTS AND CORRELATIONS

Heat transfer at nucleate pool boiling of the binary and ternary refri gerant mixtures R404A, R407C and R507 at the outside of a horizontal t ube with emery ground surface has been investigated in a wide range of pressures and heat fluxes. Together with experimental data of Bednar and Bier for wide boiling ethane/n-butane mixtures, the results of the se comparatively narrow boiling mixtures are used to investigate the i nfluence of heat flux q on the heat transfer coefficient alpha as pred icted by various correlations for nucleate boiling of mixtures. At com paratively high saturation pressures with experimental alpha-values ma rkedly smaller than the molar average of the pure components, the alph a,q-relationships predicted differ significantly from the experimental , particularly for wide boiling mixtures. (C) 1998 Elsevier Science Lt d and IIR.