Experimental study on heat transfer performance and flow visualization in microchannels with micropillars

Abstract

This research investigated heat transfer performance and flow characteristics of three polydimethylsiloxane microchannels full of deionised water as a working fluid. A single micropillar, horizontal micropillars, and vertical micropillars along the flow direction were prepared on the microchannels experimentally. Results show that the Nusselt number of microchannels with two horizontal micropillars is 19% higher than that with a single micropillar. The microchannel with two vertical micropillars has the Nusselt number is 29% higher than that with a single micropillar, which shows the best performance on the heat transfer enhancement. Visualization experiments of the flow field were carried out to explore the enhanced mechanism of the heat transfer for microchannels with various micropillar arrangements. When the flow rate is 7 mLpm, the maximum velocities near the single cylinder and the horizontal micro-column are 0.5 m/s and 0.52 m/s. Fluid velocity in a region between two vertical micropillars reaches 0.72 m/s when the flow rate is 7 mLpm. The fluid in the high-speed region is fully mixed around the micropillar, which reduces the stagnation region area down-stream of the vertical micropillar and enhances heat transfer.