矩形微通道中流体流动阻力和换热特性实验研究

Experimental study on flow and heat transfer characteristics in rectangular microchannel

以去离子水为流体工质，对其在矩形微尺度通道中的流动阻力和传热特性进行了实验研究。通过测量流量、进出口压力和温度等参数，获得了流体流过微通道时的摩擦阻力系数、对流换热过程中的热流通量和Nu等。微尺度通道中流体流动的摩擦阻力系数较常规尺度通道中的摩擦阻力系数小，仅是常规尺度通道中摩擦阻力系数的20％～30％；且流动状态由层流向湍流转捩的临界Re也远小于常规尺度通道的。微尺度通道中对流换热的Nu与常规尺度通道的显著不同。流量较小时，Nu较常规尺度通道中充分发展段的小；随着水流量的增加，微通道的Nu迅速增加，并很快超过常规尺度通道的Nu，表现出微尺度效应。热流通量对微尺度通道中对流换热Nu存在影响，其影响规律在不同流速条件下呈不同趋势，流速较小时，Nu基本保持不变；而在流速较大时，Nu随热流通量增加而呈增加趋势。

Flow and heat transfer characteristics in a rectangular microchannel were studied. All tests were performed with deionized water. The flow rate, pressures and temperatures at the inlet and outlet were measured. The friction factor, heat flux and Nusselt number were calculated. The friction factor in the microchannel is smaller than that in the conventional channel, usually only 20% - 30% of that of the convectional one. The critical value of Reynolds number below which the flow remains laminar flow in the microchannel is also smaller than that in the convectional channel. The Nusselt number in the microchannel is quite different from the convectional channel, usually smaller than that for the convectional channel when the flow rate is small. With the increase in flow rate, the Nusselt number increases significantly, exceeding the Nusselt number for the fully developed flow in the convectional channel and exhibiting a strong micro - scale effect. The Nusselt number is affected by the heat flux. The Nusselt number remains constant when the flow rate is small. The Nusselt number increases with the increasing in heat flux when the flow rate is large.