Study on the influence of refrigerant charge on performance of heat pump units

Abstract

Refrigerant charge can be determined by two methods, experiments or theoretical calculation. Experiments are usually carried out under the specific system and working condition, and the results are reliable. However, there have some problems, such as it needs a large amount of experimental work and the results are only suitable for specific systems and working conditions. The method of theoretical calculation to determine the refrigerant charge can be used in different systems and working conditions, but the reliability of the calculation results depends on the degree of coincidence between the void fraction coefficient model and the actual system. Especially for new refrigerants, the applicability of void fraction coefficient model needs further verification. In this paper, the optimum charge quantity of new refrigerant in the water source heat pump unit is studied by methods of experiment and SIMULINK simulation. The results show that the difference between simulation and experimental values is within 10%. The simulation method provides a reference for the optimization of refrigerant charge.