Developing Convective Heat Transfer in Multiport Microchannel Flat Tubes

Abstract

An experimental investigation of fluid flow friction and heat transfer coefficient in simultaneously developing flow through a multiport microchannel flat tube (MMFT) was presented. The cross-sectional geometries of five tubes were rectangular with hydraulic diameters of 0.8–1.33 mm and aspect ratio of 0.44–0.94. The working fluid was water, and the Reynolds number was in the range 150–4500. The experiment result showed that friction factor was successfully predicted by classical correlation in laminar regime, whereas the laminar–turbulent transition in the developing flow was not as obvious as in the completely developed flow. The greater aspect ratio produced stronger heat transfer capacity in the developing flow, although the effect of the aspect ratio decreased at increased Reynolds numbers for heat transfer characteristics. Moreover, the scale effect improved the heat transfer performance of MMFTs, especially at high Reynolds numbers.