微管道换热器多孔介质模型分析及应用

将微管道换热器抽象成多孔介质模型,由Brinkman-extended Darcy方程出发,分别按照双方程模型和单方程模型进行求解,以得到微管道内流体的速度场和温度场分布,并对单方程模型和双方程模型的解析解进行了对比,讨论了微管道高宽比和有效导热系数比对流动与传热的影响。证明了由基于多孔介质双方程、单方程模型所得的解析解均可用于预测微管道换热器中的容积平均速度与温度分布。利用基于多孔介质双方程模型还可得出微管道换热器的总热阻和优化设计结构,结合硅衬底上的多路感应耦合等离子体刻蚀工艺加工出了经结构优化的硅制微管道换热器。在满足局部热平衡条件下,基于多孔介质单方程模型更适用于实际工程计算,不必经由预先的试验确定换热系数。

ANALYSIS OF POROUS MEDIUM MODEL FOR MICROCHANNEL HEAT SINKS AND ITS APPLICATION

Based on the Brinkman-extended Darcy Equation, both double-equation resolving model and mono-equation resolving model for fluid flow in micro scale are designed. The analytical solutions for the velocity and the temperature profiles of fluid flow in microchannel are obtained and compared by abstracting the microchannel heat sinks as a block of fluid-saturated porous medium. Furthermore, the effects of aspect ratio and the effective thermal conductivity ration on fluid flow and heat transfer in microchannel are analyzed. It is proved that the analytical solutions of both the double-equation and mono-equation resolving models can predict the volume average profiles of the velocity and the temperature in microchannel. Notably, it is focused that the double-equation resolving porous medium model can predict the total thermal resistance and optimize the structure performance of the microchannel heat sinks. The optimized microchannel heat sinks is manufactured on the silicon wafer through multiplex inductively coupled plasma etching. On the condition of local thermal equivalence, the mono-equation resolving porous medium model can be used in practical calculation expediently without depending on the heat transfer coefficients, which can only be obtained in experiments.