Waste Heat Management in Hybrid Vehicles for Cabin Cooling

Hybrid electric vehicles are gaining popularity nowadays due to their superior fuel efficiency and benefits to the environment. As such a clear thermodynamic study on the hybrid vehicles in order to further improve the efficiency/fuel economy of the vehicle. This paper studies the effect of a vapor absorption cooling system for cabin cooling purposes. The heat required for the powering of the generator was taken from a low-grade heat source, from waste heat. Since the waste heat from the battery is insufficient for powering a cooling system, the heat from the exhaust was used. This is a low-grade heat source. A lithium-bromide (Li-Br-H2O)-based vapor absorption system is used for the work as this has better output from a low-grade heat source. A waste heat output of 14.2 KW is generally available under city conditions. The thermodynamic analysis of the proposed system was performed, and under this, a coefficient of performance of 0.721 was observed. The thermodynamic first law is used to analyze the effects of various input parameters. Input parameters considered for the analysis are the mass flow rate of the pump, the input to the generator, input to the evaporator. The system was found to be a feasible option in increasing the performance of a hybrid electric vehicle.