Performance investigation of the cascade heat pump system with waste heat recovery for electric vehicle thermal management systems on energy, economic and environmental impact

Abstract

This study addresses the inefficiencies of traditional EV thermal management systems that use a single compressor for both battery and cabin thermal needs. This configuration often results in inefficient energy utilization due to the differing thermal demands of the battery and cabin. To address these challenges, a cascade heat pump system was proposed, featuring two compressors and two independent refrigerant cycles to manage battery and cabin thermal loads separately. Additionally, the system reutilized waste heat for cabin heating under winter conditions. A simulation model, validated with experimental data, was developed to evaluate energy consumption under various scenarios, including diverse charging conditions and driving cycles. The results demonstrated that the cascade system significantly reduced energy consumption compared to conventional single-compressor systems. During battery charging, adaptive compressor control based on temperature achieved an average energy reduction of 50.2 % in summer and 25.9 % in winter. During electric vehicle operation, the cascade system consistently reduced total energy consumption across all driving cycles, improving driving range efficiency from 4.33 to 6.15 km/kWh under summer NEDC conditions. Over a 10-year period, the reduced energy consumption translated to a 16.6 % economic benefit and a 23.6 % reduction in CO₂ emissions. These findings highlight the cascade heat pump system's ability to optimize energy usage in both summer and winter, offering enhanced economic and environmental benefits for electric vehicles.