Thermal management system for power batteries

Thermal Management System for Power Batteries

The thermal management system for power batteries is mainly divided into air cooling, liquid cooling, phase change materials and heat pipe cooling based on different cooling media. The principle and system structure of different cooling methods are very different.

 

(1) Power battery air cooling: through the flow of air to make the battery pack and the outside air convection heat exchange. Air cooling is generally divided into natural cooling and forced cooling, natural cooling is when the car driving process of outside air to the battery pack cooling. Forced air cooling is the addition of a fan to force cooling on the battery pack. The advantages of air cooling are lower cost and ease of commercial application. The disadvantages are lower cooling efficiency, larger space occupation ratio and serious noise problems.

 

(2) Power battery liquid cooling: the flow of liquid allows the heat of the battery pack to be carried away. Because the specific heat capacity of liquid is larger than that of air, the cooling effect of liquid cooling is better than that of air cooling, and the cooling speed is faster than that of air cooling, and the temperature distribution of the battery pack after cooling is more uniform. For this reason, liquid cooling is also used commercially in large numbers. However, liquid-cooled cooling also has disadvantages, the disadvantages of which are the risk of liquid leakage, relatively large complexity and high maintenance costs.

(3) Phase change material cooling: Phase change materials (PCM), such as paraffin waxes, hydrated salts and fatty acids, can absorb or release large amounts of latent heat during phase change while their own temperature remains unchanged. As a result, PCMs have a large thermal energy storage capacity without the need for additional energy consumption and are widely used to dissipate heat in batteries for mobile phones and other electronic products. However, the application for automotive power batteries is still under research. Phase change materials suffer from low thermal conductivity, resulting in the surface of the PCM in contact with the battery melting while the rest of it does not, reducing the heat transfer performance of the system and making it unsuitable for large size power batteries. If these problems can be solved, PCM cooling will become the most promising development solution for thermal management of new energy vehicles.

4) Heat pipe cooling: A heat pipe is a device based on phase change heat transfer. A heat pipe is a sealed container or sealed pipe filled with a medium/liquid (water, glycol or acetone, etc.) working in a saturated state. One section of the heat pipe is the evaporating end and one end is the condensing end. It can both absorb heat from the battery pack and heat it up, making it the ideal thermal management system for power batteries at present. But its also still in the research state at present.

(5) Direct cooling of refrigerant: direct cooling is the use of R134a refrigerant and other coolant evaporation heat absorption principle, the evaporator of the air conditioning system installed in the battery box to make the battery box a way of rapid cooling. Direct cooling system has high cooling efficiency and large cooling capacity.