Condensation of n-Hexane and Isopropanol Mixed with a Noncondensable Gas in a New Plate Heat Exchanger Geometry

Abstract

This article presents a study of heat transfer during condensation of n-hexane or isopropanol with a noncondensable gas (nitrogen) in a new plate heat exchanger geometry. Three test sections were installed on the test rig devoted to condensation of mixtures, either in reflux or co-current condensation configurations. For both configurations, heat transfer measurements were carried out. In single-phase flow tests, experimental data reduced by a log mean temperature difference were compared with new correlations on the gas side, adapted to the present specific plate geometry. Correlations of the Fanning friction factor were deduced from gas-side pressure drop measurements on the two geometries tested. In two-phase flow tests, the log mean temperature difference method was assumed to be correct to the first-order for the comparison of results in two test sections. The condensation curve method was applied to the present results, and co-current and reflux condensation configurations were then compared in terms of experimental overall heat transfer coefficients. It is shown that for a gas Reynolds number higher than 2,000, heat transfer coefficients in reflux condensation become higher than those for co-current condensation. Flooding phenomena were observed for specific experimental conditions in reflux condensation mode. The flooding experimental data are compared with five existing correlations (i.e., Wallis, modified Wallis, English et al., McQuillan & Whalley, and Zapke & Kröger) to observe fluid property effects for the same ranges of heat duty and mass flow rates in the condenser. The English et al. and Zapke & Kröger correlations show the best agreement with experimental flooding data in the present geometry.