As countries around the world have announced their commitment to control CO2 emissions and improve fuel efficiency in order to suppress global warming, the shift from conventional internal combustion engine vehicles to electric vehicles is being promoted worldwide. Air conditioners for internal combustion engine vehicles use waste heat from the engine as the heat source. However, in the case of electric vehicles, the heat source is insufficient for their air conditioners because there are no engines. Typically, electric vehicles use a refrigeration cycle with a heat pump to absorb heat from the outside air as a heat source. However, due to the physical properties of conventional refrigerants, heating performance is insufficient when the outside temperature is low. Therefore, electric heaters are generally used to ensure heating performance, which increases the overall cost of the vehicle due to the cost of electric heater-related parts. As such, Mitsubishi Heavy Industries Thermal Systems, Ltd. has developed an air conditioning system for electric vehicles that can contribute to the improvement in cabin comfort under low outside air temperature conditions by combining refrigerant and coolant circuits without the use of electric heaters. This report introduces the developed system.
