非圆形微通道热沉的流动换热特性数值模拟

Numerical Simulation of the Heat Exchange Characteristics of the Flow in a Noncircular Microchannel Heat Sink

建立了非圆形硅微通道内单相流动和换热过程的三维模型,并分别对三角形、矩形和梯形微通道中流动换热进行了数值模拟。研究发现,截面平均努塞尔数在通道入口处数值最大,然后沿流体流动方向急剧减小,直至流动充分发展时趋于恒定。固体和流体温度沿流动方向近似线性升高。换热面壁温仅沿流动方向升高,在垂直于流动方向,温度则基本保持均衡;雷诺数对微通道的流动与换热特性存在着较大的影响,雷诺数越大,其对应的努塞尔数也越大。对3种微通道的热经济性分析比较发现,三角形通道的热有效性最高。

Established was a three-dimensional model for a single-phase flow and heat exchange process in a noncircular silicon microchannel,and numerically simulated was the heat exchange of flows in a triangular,rectangular and trapezoidal microchannel respectively.It has been found that cross-sectional averaged Nusselt number attains a maximum value at the inlet of the channel,and then will drastically decrease along a fluid flow direction.It tends to be constant when the flow has been fully developed.Both solid and fluid temperatures grow in an approximately linear way along the flow direction.The wall temperatures on the heat exchange surfaces increase only along the flow direction and those along the direction perpendicular to the flow,however,basically maintain an equilibrium state.Reynolds number exercises a relatively big influence on the flow and heat exchange characteristics of the microchannel.The higher the Reynolds number,the greater the corresponding Nusselt number.It has been found through the analysis and comparison of the thermodynamic cost-effectiveness of three kinds of microchannels that the triangular channel enjoys a maximal thermodynamic effectiveness.