针状电极作用下的微细通道流动沸腾传热

为探究电场对微细通道流动沸腾传热的影响，设计了一种针状电极布置方案将电场引入到微细通道中，以制冷剂R141b为实验工质，在设计系统压力为140kPa、入口温度为32.5℃工况下进行流动沸腾实验。研究结果表明：电场对制冷剂R141b在微细通道内的流动沸腾传热效果有显著影响，引入电场会导致过冷沸腾起始点（ONB点）提前，强化了传热效果，相对于无电场的情况，250V、550V、850V这3种电压下达到ONB点所需过热度分别减小了0.6℃、1.26℃、1.78℃；电场能够显著强化位于ONB点后下游区域的沸腾传热，局部传热系数随着电压的增大而增大，在本实验工况下局部沸腾传热系数最大提高了89.7%；将3种传热模型进行对比，发现Sun-Mishima模型预测效果最好，引入电压参数U对其修正，修正后的模型能更好预测本实验工况下的传热系数实验值，平均绝对误差为12.2%。

Flow boiling heat transfer enhancement in microchannelsunder needle electrode

To investigate the effect of electric field on flow boiling heat transfer in microchannels, a needle electrode arrangement was designed to introduce the electric field into the microchannels with designed capacity of system pressure at 140kPa and inlet temperature at 32.5℃ by using the refrigerant R141b as the experimental working fluid. The experimental results indicated that the electric field has a significant effect on the flow boiling heat transfer of the refrigerant R141b in microchannels, promoting onset of nucleate boiling (ONB) and enhancing heat transfer performance. Compared to the condition without electric field, the required superheat at ONB on 250V， 550V， 850V was reduced by 0.6℃, 1.26℃, and 1.78℃ respectively. The electric field can significantly enhance the boiling heat transfer in the downstream region after the ONB point. The local heat transfer coefficient increases with the increase of voltage and the partial boiling heat transfer coefficient increases by as much as 89.7% under the experimental conditions. Three heat transfer models were selected for comparison. It was found that the Sun-Mishima model has the best prediction and the model revised by introducing the voltage parameter U could better predict the experimental value of the heat transfer coefficient under the experimental conditions and the mean absolute error is 12.2%.