Experimental Investigation of the Parameters Influencing Refrigerant Migration in a Refrigeration System

Abstract

Refrigerant migration, which is characterized by the pressure equalization between condenser and evaporator during compressor off period, is one of the most effective cycling losses phenomena with the cause of 5–15% increasing rates in the energy consumption of a refrigeration system. In this study, an experimental facility was set up to investigate the parameters influencing refrigerant migration. A freezer cabinet with wire&tube evaporator and R600a and R134a reciprocating compressors were used. For the detailed control of various condensing parameters (condensing temperature, pressure, condensing rate in the condenser) a double-tube water-cooled condenser was designed. The condenser was constructed to allow the application of various lengths. Temperature and pressure values on various points of the system, refrigerant mass-flow rate, compressor power and consumed energy values were measured simultaneously. Condensing pressure and condensing rate in the condenser, condenser length, cycling frequency, refrigerant type used in the system, and ambient temperature were investigated as parameters influencing refrigerant migration. Refrigerant migration during the off period was blocked with a solenoid valve that is located before the inlet of the expansion device, and energy consumptions and COP values were mainly compared for the opened-valve and closed-valve conditions for each controlled experimental parameter.