R141b在矩形微尺度通道中的两相流传热特性

设计搭建水力直径分别为1mm和0.5mm的矩形微尺度通道实验台，研究了以R141b型制冷剂作为工质的两相流沸腾传热特性。实验取热流密度为1～16kW/m2、质量流速为111.1～333.3kg/(m2·s)和质量干度为0～1，分析了三者对平均传热系数的影响，探究影响换热的主导因素。结果表明:热流密度较高时，平均传热系数随热流密度增加而减小，流动换热主要受到沸腾传热的影响；当质量流速较大且热流密度较低时，平均传热系数随热流密度增加而有所增长；热流密度较低时，平均传热系数随质量流速变化明显，热流密度升高到一定值后，质量流速对平均传热系数的影响很小；当质量流速处于111.1～333.3kg/(m2·s)时，平均传热系数随质量干度的增加而减小。 

Two-phase heat transfer characteristics of R141bin rectangular micro-channels

An experimental study of two-phase flow heat transfer characteristics in rectangular micro-channels of 1mm and 0.5mm hydraulic diameter was conducted. R141b was used as the working fluid. In this experiment, the heat flux ranged from 1 to 16kW/m2, the mass flow rate ranges from 111.1kg/(m2·s) to 333.3kg/(m2·s), and the mass vapor quality ranged from 0 to 1. In order to know the main factor affecting heat transfer, the relationships of average heat transfer coefficient between heat flux, mass flow rate and mass vapor quality were analyzed. Result showed that, when the heat flux was low, the average heat transfer coefficient decreased as heat flux increase was affected by boiling heat transfer, and the opposite trend came when the mass flow rate became large. Under the condition of low heat flux, the average heat transfer coefficient changed obviously with the mass flow rate, and the mass flow rate had weak effect on the average heat transfer coefficient after the heat flux increased to a certain value. When the mass flow rate ranged from 111.1kg/(m2·s) to 333.3kg/(m2·s), the average heat transfer coefficient decreased as mass vapor quality increased.