Development of Energy-Saving Battery Pre-Cooling System for Electric Vehicles

The performance, lifetime, and safety of electric vehicle batteries are strongly dependent on their temperature. Consequently, effective and energy-saving battery cooling systems are required. This study proposes a secondary-loop liquid pre-cooling system which extracts heat energy from the battery and uses a fin-and-tube heat exchanger to dissipate this energy to the ambient surroundings. The liquid then passes through a chiller to complete the cooling loop. The air-conditioning system is also used to cool the battery only if the temperature of the cooling water exceeds the maximum permissible temperature. The cooling load of the air-conditioning system is thus greatly reduced. The feasibility of the proposed cooling system is demonstrated experimentally under four simulated seasonal environmental conditions, namely high summer (35 °C), mean summer (30 °C), spring and fall (20 °C), and winter (7 °C). The results show that the pre-cooling system can dissipate 1000 W of battery heat in high summer, 2000 W in low summer, 3167 W in spring and fall, and more than 4000 W in winter. In other words, the pre-cooling system greatly reduces the cooling load of the air-conditioning system, and hence significantly reduces its energy consumption.