Experimental study of propane heat pump system with secondary loop and vapor injection for electric vehicle application in cold climate

In order to solve the problem that the driving range of electric vehicles (EVs) is reduced due to heating in cold climate, and the traditional R134a needs to be replaced by more environmentally-friendly refrigerants, a novel solution of coupling the secondary loop and vapor injection technology (SL + VPI) was proposed. Although propane has high flammability, it is still considered a promising alternative because of its low global warming potential (GWP), high performance, and less charge mass. The impacts of VPI technology, ambient temperature, waste heat recovery power, compressor speed, indoor inlet air flow rate, and charge mass on the heat pump system performance have been experimentally studied. In addition, the heating performance and driving range improvement of different heat pump systems were compared. The results show that at-20 C ambient tem-perature, the propane SL + VPI system was second only to CO2 direct heat pump system; its heating performance was 33.3-37.4 % greater than the propane direct heat pump.

Automated summary

The novel solution of coupling the secondary loop and vapor injection technology (SL + VPI) using propane as a refrigerant shows promising results in improving heating performance and driving range in cold climate.