Evaluation of Transient Refrigerant Migration Modeling Approach on Automotive Air Conditioning Systems

Automotive air conditioning systems are subject to constantly changing operation conditions and steady state simulations are not sufficient to describe the actual performance. The refrigerant mass migration during transient events such as clutch-cycling or start-up has a direct impact on the transient performance. It is therefore necessary to develop simulation tools which can accurately predict the migration of the refrigerant mass. To this end a dynamic model of an automotive air conditioning system is presented in this paper using a switched modeling framework. Model validation against experimental results demonstrates that the developed modeling approach is able to describe the transient behaviors of the system, and also predict the refrigerant mass migration among system components during compressor shut-down and start-up (stop-start) cycling operations. To further investigate the potential of the dynamic modeling tools, two simulation examples of evaluating the system performance are given in the paper: (i) impact of system component variations on the refrigerant mass migration; and (ii) control implementation for the system start-up performance improvement.