Integrated design of multi-circuit thermal management system with battery waste heat utilization for new energy vehicle and performance assessment

A multi-circuit integrated thermal management system for new energy vehicle is proposed to realize the different coupling relationship between the heat exchanger for the cabin and the chiller for the battery through the four-way reversing valves and the solenoid valves. The effects of circuit selection, ambient temperature, driving test conditions and waste heat utilization on thermal management performance are discussed. The results indicate that thermal management can be carried out through three circuits in the system for heating conditions. The cabin is heated first in Circuit 1 and Circuit 3, while the battery has a higher priority in Circuit 2. The energy consumption in Circuit 1 is close to that in Circuit 2 at different ambient temperature. Compared with the other two circuits, Circuit 3 is more power-efficient, with energy consumption reduced by 14.81 %, and energy efficiency increased by 0.11 and 0.13 respectively at 10 °C of ambient temperature. The thermal management performance of Circuit 2 is least affected by the driving test conditions, and the maximum time difference of battery heating completion under different conditions is 284 s. High vehicle speed is beneficial to the waste heat utilization of the battery, for intense driving conditions, the energy consumption reduction ratio in Circuit 1 and Circuit 2 is more than 19.50 % and exergic efficiency is increased by more than 1.01 % in each circuit. Circuit 1 and Circuit 2 are better for intense driving conditions, and Circuit 3 is a good choice for urban driving conditions.