Experimental analysis on the heat transfer performance of gas-liquid Taylor flow in a square microchannel

Abstract

The flow and heat transfer behaviors of gas–liquid Taylor flow in a 1 × 1 mm square microchannel are experimentally investigated in this paper, focusing on evaluating the slug length, void fraction β, and mixing velocity on the overall performance of Taylor flow in the microchannel. T-shaped junctions of varying widths were employed to control the slug length in the Taylor flow. The experimental results indicate that reducing the junction width can heighten the bubble generation frequency and shorten the bubble/slug length. This reduction in slug length can enhance the heat transfer performance of the Taylor flow in fixed cross-section microchannels, but the degree of enhancement is significantly influenced by the void fraction. When β = 0.5, reducing the slug length can significantly improve the heat transfer coefficient while maintaining a reasonable pressure drop increment, resulting in the best overall performance. The friction pressure drop increases significantly when β = 0.67, and the level of overall performance is low. When β = 0.33, the short slugs have little effect on the performance of Taylor flow, and the change of heat transfer and the friction coefficient is only within 3%. In general, increasing the mixing velocity can improve the overall performance of the Taylor flow. However, at a relatively low void fraction, the pressure drop increase outweighs the heat transfer coefficient, leading to a decline in overall performance. Finally, a correlation is proposed to predict the Nu number under Taylor flow in the three-sided heated rectangular microchannel, with an average error of 11.77%.