Four major cooling technologies for battery thermal management systems
Compared to the chips that generate the most heat in electronic products, the heating component of electric vehicles is the power battery. Therefore, research on thermal management technology for power batteries is one of the most crucial projects for both battery manufacturers and automotive companies.
The most primitive way of heat dissipation technology is through air cooling, which can be divided into two types: active cooling and passive cooling. Both active and passive heat dissipation utilize air to carry away heat. Passive heat dissipation is relatively simple, mainly consisting of air intakes, ventilation routes, and air outlets. When the vehicle is in motion, the heat is carried away by the contact between the air and the battery.
However, the biggest drawback of passive heat dissipation is its insufficient heat dissipation efficiency. Once the input/output power of the battery is increased, the heat generation increases, and the effect is negligible. For example, when charging, how can the vehicle dissipate heat without driving? Therefore, active heat dissipation enhances air flow and improves heat dissipation by adding fans and other devices to suck in air.
The liquid cooling technology has a better heat dissipation effect than air, which exchanges heat with the power battery through coolant pipes distributed inside or on the surface of the battery, resulting in more efficient heat dissipation. Liquid cooling heat dissipation is achieved by placing coolant pipes or cooling plates (with coolant inside) directly inside the power battery, and then using relevant components to allow the coolant to flow and take away the internal heat of the battery. The key to liquid cooling heat dissipation is also a point that directly affects the heat dissipation effect of the power battery, which lies in the design, laying, and flow direction of the coolant pipeline. Only by forming a reasonable reflux path and achieving uniform heat dissipation can the overall heat dissipation of the power battery be maintained at a uniform temperature level, without some temperatures being too low and others being too high, which will affect the health of the battery.
In recent years, there has been an emerging passive heat dissipation method - phase change material heat dissipation technology. Phase change materials are cooling materials that can absorb or release a large amount of heat during phase change, and can maintain a constant temperature to control the surrounding temperature. The most common phase change material in our lives is undoubtedly water. When the temperature drops to 0 ° C, water changes from liquid to solid (freezing and releasing heat); When the temperature is above 0 ° C, water changes from solid to liquid (dissolution heat absorption).
In addition to the above three heat dissipation methods, there is also an active cooling technology - thermoelectric cooling, an energy conversion technology that utilizes the Peltier effect of semiconductor materials to achieve cooling or heating. After connecting to a DC power supply, the heat at one end of the thermoelectric refrigeration device will be absorbed, resulting in a decrease in temperature, while the temperature at the other end will increase simultaneously; Furthermore, this phenomenon is completely reversible, as changing the direction of the current can transfer heat in the opposite direction.
As the most classic technology, air cooling technology can no longer meet the cooling needs of power batteries and has been replaced by liquid cooling technology. Liquid cooling has become the most mature and widely used cooling technology for power batteries. However, with the increase of battery heat, battery power, and charging speed, liquid cooling will gradually be unable to meet the heat dissipation needs of the battery. Therefore, the emerging phase change material heat dissipation technology and thermoelectric cooling technology have great potential, but both need to be combined with other technologies to achieve the best results. At present, there is no absolutely high-quality heat dissipation technology, and the future technology trend will combine multiple heat dissipation technologies to meet different heat dissipation needs.
