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对水平微圆管内非共沸混合工质R32/R134a的流动沸腾压降进行了试验,同时可视化观察了微圆管出口处的气泡行为.在此基础上分析了主要工况参数对微圆管内流动沸腾压降的影响,比较了微圆管、细圆管和常规管道内的两相流动压降特性.结果表明:微圆管内流动沸腾压降随质量干度和质量通量密度的增加而平稳增加.当热通量较低时,微圆管内压降增加幅度较小,但当热通量达到一定值时,微圆管内压降则以较大幅度升高.相同试验工况下微圆管内流动沸腾压降远大于常规管道.综合考虑流动压降和换热效果时,存在最佳通道结构使其换热经济性最好.
The flow boiling pressure drop of non-azeotropic mixed refrigerant R32 / R134a in horizontal micro-tubes was tested, and the bubble behavior at the outlet of micro-tubes was visually observed.On the basis of the analysis, Flow boiling pressure drop, the pressure drop characteristics of two-phase flow in micro-tube, thin-tube and conventional pipe were compared.The results show that the pressure drop of flow boiling in the micro-tube increases with the increase of mass and mass flux density When the heat flux is low, the increase of pressure drop in the micro-tube is small, but when the heat flux reaches a certain value, the pressure drop in the micro-tube increases with a big margin.Under the same experimental conditions The pressure drop of flow boiling in the circular pipe is much larger than that of the conventional pipe, and considering the flow pressure drop and the heat transfer effect, the best channel structure is the best heat exchanger.