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建立微尺度通道流动沸腾换热试验台,采用高速摄像仪对水平微尺度单管(内径0.8 mm)内低沸点制冷工质(R32/R134a(25%/75%))气液两相流动特性进行可视化观察研究分析,获得了流型照片。在各种质量流量和进口干度下对工质在微尺度管内的两相流流动特性进行了试验,观察到了各种工况下流型的转化特点,对流型的影响因素进行分析。试验工况为:质量流量G=760～10 360 kg/(m2.s),进口干度x=0.01～0.77。实验结果表明:在较高的质量流量工况下,工质在微尺度单通道内的流型比较单一,主要呈气状流/雾状间隔流动。在进口质量干度较低的情况下,也会出现比较明显的环状流,但液膜总处于波动状态,有不稳定现象。无论什么工况,均没有出现像常规通道内的分层流动现象。
A micro-scale channel flow boiling heat transfer test bed was set up. The gas-liquid two-phase flow characteristics of low boiling point refrigerant (R32 / R134a (25% / 75% Visual observation and analysis, obtained a flow-type photos. Under different mass flow rates and inlet dryness, the flow characteristics of two-phase flow in a micro-scale tube were tested. The conversion characteristics of the flow pattern under various operating conditions were observed and the influencing factors of the flow pattern were analyzed. Test conditions: mass flow G = 760 ~ 10 360 kg / (m2.s), import dryness x = 0.01 ~ 0.77. The experimental results show that the flow pattern of the working fluid in the single-channel at the micro-scale is relatively single under the condition of high mass flow, and the flow pattern is mainly in the form of gas flow / mist interval. In the case of lower import quality dryness, there will be more obvious annular flow, but the liquid film is always in a volatile state, there is instability. No matter what conditions, there is no phenomenon like the stratified flow in the conventional channels.