What Refrigerant Should New Energy Vehicles Use?

Now, the new energy vehicle industry is booming. There is sufficient engine waste heat in traditional fuel vehicles for heating in winter, but the lack of engine waste heat in new energy vehicles makes winter heating an important problem that must be solved in vehicle refrigeration systems. So what kind of problems are faced in the development of new energy vehicle air conditioning systems? What kind of refrigerant should new energy vehicles use?

At present, the types of refrigerants used in new energy vehicles still follow the technical route of traditional fuel vehicles, that is, HFC refrigerants are still used. Among them, passenger cars mainly use R134a as the working fluid, while commercial vehicles (passenger cars and rail vehicles, etc.) mostly use R407C as the working fluid. In terms of cooling, the comparison of R134a and R407C vehicle air conditioning systems can not only ensure almost the same cooling speed and cooling energy efficiency, but also usually use smaller compressors and heat exchangers, which is of great significance for the lightweight vehicle equipment. With the popularization of new energy vehicles, a major problem has become prominent, that is, there is sufficient engine waste heat in traditional fuel vehicles for heating in winter, but the lack of engine waste heat in new energy vehicles makes winter heating a must for vehicle cooling systems. important issue.

To this end, scholars began to study the heat pump heating performance of R134a, R407C, and other systems. The main research results are as follows:

1. R134a heat pump air conditioning system. Similar to household air conditioners, the vehicle air conditioner heat pump system also switches between cooling and heating modes through a four-way reversing valve. The cabin heating can be achieved quickly above the ambient temperature of 0°C, but the heating capacity has been significantly attenuated when it runs to -15°C.

2. Build a heat pump bench similar to an electric vehicle. The experimental results show that the R134a working fluid still has an ideal heating COP at an ambient temperature of -5°C, but the situation at lower temperatures is not mentioned.

3. R134a vehicle heat pump system. At -10°C, its heating COP and heating capacity can reach 3.26 and 3.10 kW, respectively. Although the COP value is acceptable, the heating capacity has been severely attenuated to the point where it cannot meet the heating demand of the cabin.

Considering the heat attenuation problem of R134a and R407C heat pump systems at lower ambient temperatures, conventional R134a and R407C systems usually need to increase the compressor speed or install a larger capacity compressor to ensure sufficient heating at low ambient temperatures. On the other hand, from the perspective of improving the COP of circulating heating, and referring to mature technologies in domestic and commercial heat pumps, we will use components such as expansion tanks or economizers to construct the system structure of the intermediate air supply type and carry out numerical simulation and experimental research respectively. To a certain extent, the scope of application of the R134a and R407C heat pump systems in the low-temperature environment of vehicles is broadened, and the heating COP is increased by about 10%. However, considering the difficulty of engineering the application of complex systems, the actual implementation scheme of most passenger cars and commercial vehicles is still conventional R134a or R407C systems with PTC electric heating for collaborative heating, even at temperatures below -15°C. The use of pure PTC heating in a severely cold environment has great room for improvement in both energy saving and environmental protection.