恒壁温下梯形硅微通道热沉流动换热特性

Heat transfer in trapezoidal silicon microchannel heat sinks with constant wall temperature

建立了恒壁温条件下微通道中层流流动换热的三维模型,对水力直径分别为108,160和200μm的梯形硅微通道内单相流动换热特性进行了数值模拟研究.研究结果表明:在恒壁温条件下,通道入口段Nu数最大,并沿流程逐渐减小,直至达到充分发展时,Nu数趋于定值;与大管道经典理论不同,充分发展段Nu数随Re数的增加而增加;通道尺度的减小能有效强化换热;恒壁温条件下的平均Nu数总是低于恒热流条件下平均Nu数.同时,对流动阻力损失的研究发现,Poiseuille数与经典值基本吻合.

A three-dimensional model with constant wall temperature condition has been developed to simulate the laminar convective heat transfer in trapezoidal silicon microchannels, which have hydraulic diameter of 108, 160 and 200 μm respectively. The simulation results indicate that the Nu number has a much higher value near the channel inlet and decreases along the flow direction, approaching a constant value at the fully developed region. Different from the conventional theory, the Nu number at the fully developed region in microchannels increases with the increase of Re number. The heat transfer will be enhanced by the decrease of the channel diameter. The average Nu number at constant wall temperature is always lower than that at constant heat flux condition. Pressure drop is also analyzed. It is indicated that Poiseuille number is almost the same as the classical value.