In-tube condensation of zeotropic fluid mixtures: A review

The condensation of multi-component mixtures in tubes is critical to the function of many energy conversion processes. This paper reviews experimental and analytical studies of the coupled heat and mass transfer phenomena during condensation of different fluid mixtures in different in-tube geometries. Experimental studies on condensation of binary and higher order mixtures in vertical and horizontal smooth and enhanced tubes are discussed. For zeotropic mixtures the heat and mass transfer resistances in the vapor and liquid phases increase the overall heat transfer resistance beyond what would be expected from a weighted average of corresponding resistances for the pure components. There are significant opportunities to improve the quality of available data for new fluid combinations in smaller channels and at fine mass quality increments. Four categories of models are reviewed (1) Conservation equation (2) Non-equilibrium film theory (3) Equilibrium and (4) Empirical models.