The existence of non-equilibrium two-phase flow of R600a at subcooled temperature in a vapor compression refrigeration system.

Most of vapor compression refrigeration systems are designed such that the refrigerant is a subcooled liquid state at the condenser outlet. In this study, experiments were conducted to investigate the refrigerant state between at the condenser outlet and capillary tube inlet. The experimental apparatus equipped with thermocouples, pressure measurements, and visualization device was installed and operated with R600a as a refrigerant. The visual observation shows that the refrigerant flows in a two-phase state at the condenser outlet although the temperature of the refrigerant is much lower than the saturation temperature corresponding to its pressure. A method to calculate the specific enthalpy of the two-phase mixture at subcooled temperature was proposed. Experiments were conducted to verify the proposed method in various test conditions. The calculated enthalpy using proposed method in this study well agreed with the measured values.

绝大多数蒸汽压缩制冷系统的设计均使制冷剂在冷凝器出口处处于过冷液态。本研究通过实验探究了冷凝器出口与毛细管入口之间的制冷剂状态。本研究搭建了搭载热电偶、压力测量装置与可视化设备的实验平台，并以R600a作为实验制冷剂。可视化观测结果表明，尽管制冷剂温度远低于其压力对应的饱和温度，但其在冷凝器出口处仍以两相流状态流动。本研究提出了一种用于计算过冷温度下两相混合物比焓的方法，并通过多工况实验对该方法进行了验证。本研究采用所提方法计算得到的比焓值与实验测量值吻合良好。