Enhanced boiling of mixtures

Abstract

The degradation in the mixture pool boiling heat transfer coefficient is demonstrated to be much different for an enhanced boiling tube than for an ordinary smooth tube operating under identical conditions, usually being substantially less pronounced. This phenomenon is explored in the present study for the High Flux tube with its thin, porous metallic enhancement layer. The reduced degradation in the enhanced boiling heat transfer coefficient is shown to be the result of a liquid Prandtl number augmentation of the liquid-phase convection process inside the porous matrix, which partially counterbalances the negative effect of mass diffusion on the thin film evaporation process in enhanced boiling. It is thus concluded that the existing mixture boiling correlations for conventional smooth tubes, which only include the mass transfer effect on evaporation, will not be able to correlate the mixture effect for enhanced surfaces.