Investigation of reduction in refrigerant charge for domestic split air conditioner

Abstract This study analyses the vapor compression cycle for the reduction of refrigerant charge without affecting the cooling capacity and COP. Globally, use of natural refrigerants is increasing. HC-290 is a possible refrigerant. HC-290 is highly flammable and is classified under A-3 safety class. Charge reduction below the safe operating limit is the requirement. The condenser carries majority of the charge in the vapour compression cycle. (VCC) Improvement in condenser internal volume by the change in flow direction by modifying the condenser orientation indicates a potential method for charge reduction. Analysis is carried out for a falling film condenser (FFC) for the use of HC-290 refrigerant in split type air conditioner (STAC) of cooling capacity of 5000 W complying the flammability limit as per international standard. Analytical calculations for the FFC and the CFD simulation for the falling film condensation has verified charge reduction. An experimental set up with same condenser tube was built. Number of condenser tubes in service were different compared to standard STAC condenser. At different operating conditions cooling capacity was monitored. The VCC process parameters were measured and cooling capacity, power consumption and coefficient of performance (COP) were calculated. When the 25% condenser tubes were not in service compared to all tubes in service, cooling capacity reduced by 2% compared to baseline cooling capacity. The energy consumed was marginally reduced so higher COP was observed. The charge reduction of 45 g is observed with near to no compromise on cooling capacity.