Performance Simulation And Charge Study Of Automobile Air Conditioning System

In the field of automotive air conditioning, the main way to deal with energy crisis and environmental issues is to improve system performance and reduce greenhouse gas emissions. Parallel flow heat exchangers have be used widely in automotive air conditioning systems, due to its high-performance, compact structure, and less refrigerant charge. Since the refrigerant charge level has significant impact on capacity and efficiency of air conditioning system. Therefore, it’s important for the automobile air conditioning system charged with an optimum amount of refrigerant. However, Most of the previous studies were focused on the automobile air conditioning system with parallel flow type condenser and laminated type evaporator. Studies on the automobile air conditioning system with parallel flow type evaporator and condenser is very limited in the open literature. And the studies related to effects of refrigerant charge is less.In this paper, a steady state simulation model has been developed for the R134a automotive air conditioning system, which includes a parallel flow evaporator and a parallel flow condenser. Based on the system model, the performance and refrigerant charge of the AAC are studied. In addition, the methods to reduce greenhouse gas R134a charged in the automotive air conditioning systems are discussed.First, parallel flow condenser, evaporator steady-state distribution parameter model, as well as compressor, thermal expansion valve lumped parameter model are developed on the Matlab. Analyze the relationship between the performance of parallel flow heat exchangers and the variable ambient temperature and air flow velocity; then, the equilibrium conditions of the various components are coupled to form the steady-state simulation model of the automobile air conditioning system. And use the system simulation model to calculate the effective refrigerant charge of system; last, develop the system charge model, and observe the influence of charge level on the refrigerant distribution and system performance, particularly for the cooling capacity and COP. Specific charge is taken as criterion index to evaluate the new automobile air conditioning system.Refer to the relevant literature, the model simulation results agree well with the actual situation. It could be used to investigate the automotive air conditioning systems performance under different operating conditions, as well as reduce considerable human and material resources of experiments for determining the system optimal charge.