Types of Battery Cooling System
There are two ways to cool the battery pack: air cooling and liquid cooling. Research shows that the air cooling method is easy to implement, but the temperature gradient of the battery pack changes greatly, which is not conducive to the stable operation of the battery. Liquid cooling, which uses coolant to exchange heat with the refrigerant of the air conditioning system, has gradually become mainstream.
1. Air cooling: Air cooling is a heat dissipation method that uses low-temperature air as the medium and uses heat convection to reduce the battery temperature. It is divided into natural cooling and forced cooling (using fans, etc.). This technology uses natural wind or fans, combined with the car’s own evaporator to cool the battery. The system has a simple structure and is easy to maintain. It was widely used in early electric passenger cars.
2. Liquid cooling: Liquid cooling technology uses liquid convection heat exchange to take away the heat generated by the battery and reduce the battery temperature. The liquid medium has high heat transfer coefficient, large heat capacity, and fast cooling rate, which has a significant effect on reducing the maximum temperature and improving the consistency of the temperature field of the battery pack. At the same time, the thermal management system is also relatively small. The form of the liquid cooling system is more flexible. The battery cells or modules can be immersed in liquid, cooling channels can be set up between battery modules, or a cooling plate can be used at the bottom of the battery. When the battery is in direct contact with liquid, the liquid must be insulated (such as mineral oil) to avoid short circuit. At the same time, the air tightness requirements for liquid cooling systems are also high. In addition, there are mechanical strength, vibration resistance, and life requirements. Liquid cooling is currently the preferred solution for many electric passenger cars.
3. Direct cooling (refrigerant direct cooling): Using the principle of latent heat of evaporation of refrigerant (R134a, etc.), an air conditioning system is established in the vehicle or battery system, and the evaporator of the air conditioning system is installed in the battery system. The refrigerant evaporates It evaporates in the device and quickly and efficiently takes away the heat of the battery system to complete the cooling of the battery system.