微通道形状对自相似热沉综合性能的影响分析

An investigation on the influence of the microchannel shape on performance of a self-similar micro-channel heat sink

自相似微通道热沉(SSHS)作为一种新的换热结构设计,比一般的微通道热沉(MHS)具有更好的综合性能。前期工作通过将内部分流通道改为渐缩式斜坡结构,使内部流量分配不均受到了很大抑制。本文在此基础上,利用数值模拟方法进一步分析了微通道(溢流通道)形状对SSHS流动及传热过程的影响。计算结果表明,原设计中溢流通道内存在较大的低流速区,导致了不均匀的换热过程;将矩形截面微通道改为梯形截面,可以减小溢流通道内低速区的流通面积,从而使微通道内的流动和换热过程更加均匀;进一步对比分析发现,随着溢流通道顶部宽度mw减小,低流速区域占比进一步减小,换热均匀性有所提高;该结构优化方案对流动阻力的影响较小,流量在0.18~1.8kg/h范围内,流动阻力增加平均不超过5%,但换热均匀性平均提高15%左右。

As a new design of heat sink, Self-similarity rnicchannel heat sink （SSHS） has a better overallperformance than a common Mierochannel heat sink （MHS）. The manifold channel of the SSHS was modifiedto a contracting tapered one in our previous work, making an improved internal flow distribution. A furthernumerical work in current work was carried out to analyze the influence of the microehannel （overflow channel）shape on the flow and heat transfer process inside a self-similar heat sink. The results showed that there existsa relatively large low velocity region in the overflow channel, resulting in the uniform heat transfer prc^esswherein. With changing the rectangular microehannel to a trapezoid one, the low velocity region could bereduced, realizing a more uniform flow and heat transfer process inside the microehannel. With the rnwdecreasing, the proportion of the low velocity region was reduced further and the uniformity in heat exchan4gewas improved accordingly. In the meantime, this optimization scheme had little effect on flow resistancg Theheat transfer uniformity was increased about 15% with a sacrifice of the increase in flow resistance no more than5% with the flow rate coveting 0. 18--1. 8kg/h.