Refrigerant distributions and dynamic migration characteristics of the transcritical CO₂ air conditioning system

Research on refrigerant mass migration and distribution could not only provide deep understanding of the system performance enhancement, but also contribute to searching the high risk components caused by the Boiling Liquid Expanding Vapor Explosion (BLEVE) due to the high operation pressure of transcritical CO₂ system. An experimental bench and a mathematical model of the transcritical CO₂ automotive air-conditioning system were set up to explore the refrigerant migration characteristics at different operation conditions. Simulated results of the system were validated by experiments. The distribution characteristics of the refrigerant under different charge were studied and the refrigerant charge suggestions were given. Then, under the appropriate refrigerant charge, the migration characteristics of the refrigerant in the automobile air conditioning system were simulated in the process of startup and shutdown of the compressor and conversion of cooling mode. Furthermore, influence of the parameters, such as ambient temperature, air flow rate, compressor speed on the characteristics of the refrigerant distribution in the air-conditioning system were studied. The results could provide reference for the system design and system safety.