Almost 100% of new passenger cars sold in the EU use HFO-1234yf as refrigerant to provide air-conditioning. For electric vehicles, there is no combustion engine waste heat for heating which may be provided by direct electric resistive heating resulting in a range penalty in winter. A German manufacturer has developed a HFO-1234yf based integrated thermal system that can increase the winter cooling range by up to 20 percent. In addition to significantly reducing battery power consumption, it is easy to control and can be readily adapted to future vehicle architectures.
The balance of cooling and heating requirements for the passenger compartment and the drive battery will depend on the climatic conditions and can have a significant impact on the electric vehicle range. Air-conditioning in summer reduces range due to additional energy required for cooling the drive train battery and the interior of the vehicle. In cold winter conditions direct resistive heating by electric heaters to heat passenger compartment and drive battery can reduce the cruising range of a fully charged electric vehicle by up to half.
The integrated thermal system functions in several modes. A semi-hermetic refrigerant circuit, comprising a chiller, a coolant-cooled condenser (i-condenser), a thermal expansion valve, and an electric drive compressor. The i-condenser and the chiller have the same function as the condenser and evaporator in a conventional refrigerant circuit. In this case, however, instead of exchanging heat with air, the refrigerant exchanges heat with the coolant, thus generating hot and cold coolant flows. HFO-1234yf is used as refrigerant and the conventional vehicle coolant as the medium for heat transport between the cooling circuit and the various heat sources and sinks in the vehicle.