An experimental study of flow condensation heat transfer inside circular and rectangular mini-channels

Abstract

By using unique experimental techniques and the careful construction of an experimental apparatus, the characteristics of the local heat transfer were investigated using the condensing R134a two-phase flow in horizontal single mini-channels. The circular channels (D-h = 0.493, 0.691, and 1.067 mm) and rectangular channels (Aspect Ratio = 1.0; D-h = 0.494, 0.658, and 0.972 mm) were tested and compared. Tests were performed for a mass flux of 100, 200, 400, and 600 kg/m(2) s, a heat flux of 5 to 20 kW/m(2), and a saturation temperature of 40degreesC. In this study, the effect of heat flux, mass flux, vapor qualities, hydraulic diameter, and channel geometry on flow condensation were investigated, and the experimental local condensation heat transfer coefficients are shown. The experimental data of condensation Nusselt number are compared with existing correlations.