Prediction of Heat Transfer During Condensation of Zeotropic Mixtures in Channels

ABSTRACT

Mixtures of two or more components are used in many industries, including refrigeration, chemical, and petroleum. In recent years, the use of mixtures as refrigerants has increased drastically to replace refrigerants that harm the environment. It is therefore important to be able to accurately predict heat transfer during their condensation. Many correlations have been published, which showed good agreement with data for condensation of pure fluids from many sources, but were verified only with a limited amount of data for mixtures. The present study was undertaken to evaluate them for mixtures. Efforts were made to collect a wide range of data in round tubes and rectangular channels. The data included 43 mixtures from 26 studies, with glide up to 34.6 K. The mixture components included refrigerants, chemicals, and carbon dioxide. Flow orientations were horizontal, vertical down, and vertical upflows. The data were compared to 14 correlations. Their predictions were corrected for mass transfer effects using the Bell and Ghaly correction factor. Results with the correlations are presented and discussed. Recommendations are made about the choice of correlations in design. The effectiveness of the Bell–Ghaly method is evaluated. The effects of the surface tension and the boundary between mini and macro channels are investigated.