Thermodynamic analysis of waste heat recovery for cooling systems in hybrid and electric vehicles

In this paper, the recovered heat is examined for cabin cooling for ejector and absorption cooling cycles. Energy and exergy analyses are conducted to study the role of various design parameters on the cooling capacity. Waste heat from the battery pack, as well from exhaust gases in the Internal Combustion Engine (ICE) mode, are the inputs for the boiler and generator. In a city driving mode, waste heat of 15.4 kW will be available. Results show that transferring this waste heat to the boiler in the ejector cooling system leads to a cooling effect of 7.23 kW, with energetic and exergetic Coefficients of Performance (COPs) of 0.48 and 0.2 respectively. In the absorption cycle, the energetic COP of the system is 0.53 with a coolant capacity of 7.93 kW. Results also show that, for the electric mode, the cooling capacity is lower than 2 kW, which is insufficient to provide cooling. While recovered heat from Hybrid Electric Vehicles (HEV) can be used for vehicle cabin cooling by both ejector and absorption systems, the analysis shows that the latter system has a better coefficient of performance and cooling capacity than the ejector system.