Effects of a non-equilibrium two-phase refrigerant flow at subcooled temperatures on the performance of an R-600a refrigeration system

Previous researches reported the observation of a thermodynamic non-equilibrium two-phase refrigerant between the condenser outlet and the expansion device inlet under a subcooled condition, where the fluid temperature is below the corresponding saturation temperature. Experiments are conducted to examine the influence of the non-equilibrium subcooled two-phase state of R-600a on the performance of a refrigeration system. The enthalpy of the non-equilibrium state of the refrigerant is calculated using three different methods, and the heat rejection from the condenser and the coefficient of performance (COP) of the refrigeration system are evaluated. Compared to a case in which the refrigerant flows in an equilibrium subcooled state, the condenser heat rejection and the COP both decrease when the refrigerant is in a non-equilibrium subcooled two-phase state.