A HEAT PUMP FOR AUTOMOTIVE APPLICATIONS
A dual-loop heat pump/air conditioning system for automotive applications is presented in this article. Conventional automotive heating systems have a continuing problem in cold weather due to inadequate thermal energy supply to passenger cabin during the initial engine warm-up. The proposed dual-loop system design may overcome the delayed heating problem, so that the passenger cabin is heated shortly after engine start-up in winter conditions. Furthermore, using special four-way valves makes it possible to switch between heating and cooling modes in the dual-loop system for varying outdoor conditions. Performance of both the system components and the integrated system were tested under various conditions. The thermo-hydrodynamic performance of the heat exchangers within the system was previously analyzed by the coauthors. However, the experimental results and the developed heat transfer and pressure drop correlations are reviewed and presented in this article. For the integrated system, variation of the coefficient of performance versus system variables are analyzed, plotted, and discussed. The results of extensive system testing show that the heat pump coefficient of performance varied from 2 to 5 depending on the outdoor air conditions. It appears that, with system optimization, the proposed dualloop heating/cooling system would be viable for automotive applications.