Efficiency Improvement of Heat Pump for Low Ambient Conditions Using Waste Heat from Electrical Vehicle Traction Motor

Electric vehicles (EV) have become very significant and potential way to reduce greenhouse gas emissions on a worldwide scale. EV also provides Energy security, as it reduces the dependency on petroleum producing countries of the world. Similar to the conventional Internal Combustion Engine Cars, in Electrical Vehicles also the efficient air conditioning system is very important for providing thermal comfort and for giving safe driving conditions. In Air Conditioning systems for EV, the heating option is available in the form of Electrical heaters and Heat Pump systems. The Heat pumps have become more popular compared to the electrical Positive Temperature Coefficient (PTC) heaters because of their highly efficient and energy saving designs. However, there are still some issues with using heat pumps. One of such issue is their less Coefficient of performance (COP) at low ambient conditions. Experimental results also show that the driving range decreases by using the electric heating system in vehicles.

This paper presents a study on the solutions for increasing the efficiency of heat pump at low ambient conditions. The waste heat coming out from the Traction Motor and power electronics of Electric Vehicles is being utilized for increasing the temperature of Air, which is entering the condenser in Heating mode. This has been done using a heat Exchanger placed in front of the condenser. The study is being evaluated using Coil Designer software for component level simulations and further for the system level simulations, the Kuli software has been used. The study has also resulted in increasing the COP of the system in the Heating Mode.