Impact of Refrigerant Charge over the Performance Characteristics of a Simple Vapour Compression Refrigeration System

Experimental investigation was done to find the role of capillary tube length and amount of refrigerant charge on the overall heat transfer coefficient in condenser and evaporator and actual COP of a simple vapour compression refrigeration system. It was concluded that increasing of the refrigerant charge in the system largely enhances the overall heat transfer coefficient in the evaporator by increasing the part of space occupied by liquid refrigerant in the evaporator. Capillary tube length is important as it decides the evaporator temperature and pressure directly but also affects the tendency of refilling of evaporator with liquid refrigerant after initial start up and alters the amount of optimum charge in the system. A simple refrigeration system should be designed with minimum possible length of capillary tube to satisfy the refrigeration conditions and maximum amount of refrigerant charged in the system limited by unwanted condition of refrigerant liquid entering the compressor.