To maintain a suitable working temperature range for power batteries and ensure their safe and efficient operation in various application scenarios, a cold plate and a submerged cooling system were designed for a standard box power-battery pack. The structure was optimized, and the cooling performance of the cold plate and the submerged cooling system was compared and examined. After structure optimization, the outlet pressure drop of the battery pack cooled by the cold plate was 30 Pa, with a maximum surface temperature of the battery at 31.65 ℃ and a maximum surface temperature difference of the battery being 6.51 ℃. The battery pack with immersion cooling was surrounded by a 2 mm electrical insulating fluid around the battery. The fluid filling capacity of the standard box was 10.93 L. The outlet pressure drop was 22 Pa. The maximum temperature of the battery surface was 28.49 ℃, and the maximum temperature difference on the battery surface was 2.39 ℃. Comparing the simulation and test results, the deviation for each data was within 2%, indicating high accuracy in the simulation model. The cooling effect of the optimized immersion cooling system was better than that of the original cold plate cooling system, and the inlet flow rate was reduced from 4 L/min to 2 L/min, which further reduced the pumping power of the working fluid. Furthermore, the maximum temperature difference on the battery surface was reduced by 4.12 ℃, enhancing temperature uniformity across the battery surface. This study shows that compared with cold plate cooling, immersion cooling has a more obvious effect on reducing the average surface temperature, maximum temperature, and surface temperature difference of a battery.

Efficiency of the thermal management system directly affects the energy consumption and driving range of a vehicle. This article proposes a new integrated thermal management heat pump system and develops its control strategy. The study analyzed its performance at low temperatures for waste heat recovery. The experiments were conducted under different powers, which verified that the strategy of controlling the waste heat recovery conditions using a six-way valve can reduce the system energy consumption. In addition, in real vehicle tests at -7 ℃ and -18 ℃, the 1-hour energy consumption of the test vehicles equipped with the waste heat recovery system was reduced by 24% and 35%, respectively. The waste heat recovery system for verifying the energy-saving potential of the application increased the driving range of the electric vehicles by 22.95% under urban conditions and 37.29% under high-speed conditions.