The heat dissipation system in the new energy power battery pack can cool the new energy power battery pack. There are three ways to dissipate heat for new energy power batteries: air cooling, water cooling and direct cooling. In the air cooling mode, the heat dissipation system uses natural wind or fans to cool the battery with the car's own evaporator; in the water cooling mode, the radiator is generally coupled with the refrigeration cycle system to take away the heat of the battery through the refrigerant; in the direct cooling mode, the heat dissipation system uses the principle of latent heat of evaporation of the refrigerant to establish an air conditioning system in the vehicle or battery system, and install the evaporator of the air conditioning system in the battery system. The refrigerant evaporates in the evaporator and quickly and efficiently takes away the heat of the battery system, thereby completing the cooling of the battery system.
Air cooling technology
Air cooling technology is currently the most widely used heat dissipation technology in new energy power batteries. Forced airflow can be generated by a fan, or by headwind or compressed air during the movement of the car. Compared with other technologies, air cooling technology is relatively simple, safe and easy to maintain. Toyota's hybrid electric vehicles Prius and Honda's Insight both use air cooling, while the thermal management systems developed by Nissan, GM and other automobile companies mainly use forced air cooling.
Various types of new energy power batteries in China basically use air cooling technology, and domestic technology is basically comparable to foreign levels, and can achieve good heat dissipation performance at a low cost.
Compared with liquid cooling technology, the heat exchange coefficient between air cooling technology and the battery surface is low, the cooling and heating speed is slow, the temperature uniformity inside the battery box is not easy to control, the sealing design of the battery box is difficult, and the dust and water resistance are poor.
Water cooling technology
The water cooling heat dissipation system mainly includes: electronic water pump, heat exchanger, battery heat sink, PTC heater, expansion tank.
Water cooling technology is a cooling technology based on liquid heat exchange. It is more efficient than air cooling technology, the temperature inside the electric vehicle battery pack is more uniform, it can be integrated with the vehicle's cooling system, the heat exchange coefficient between the battery wall is high, and the cooling and heating speed is fast. However, the system using water cooling technology is more complex, heavy, difficult to repair and maintain, and there is a possibility of leakage.
Water cooling technology has been studied earlier and applied for a long time abroad. With continuous exploration, practice and improvement, the heat exchange coefficient and cooling and heating speed of the system have reached a good level. In addition, the weight of foreign water cooling systems has also been reduced through the application of new materials.
At present, foreign countries mainly use water cooling technology in automobile brands such as Tesla, GM Volt, Peugeot Citroen, and BMW i3. Tesla Model S uses water cooling technology to cool the battery. Tesla has made very in-depth designs on its battery layout, thermal management system, and battery management system to ensure that each battery cell is under supervision and its status data can be fed back and processed at any time. For a single small battery cell, Tesla will enclose it independently in a steel compartment. At the same time, the liquid cooling system can be specific to cool each battery cell, reduce the temperature difference between each other, and relatively reduce the risk of battery spontaneous combustion.
In recent years, with the continuous advancement of my country's new energy power battery cooling system technology, water cooling products have shown a trend of gradually replacing air cooling products.
Related automobile manufacturers such as BYD and Geely have applied water cooling products to their new energy vehicles. In the future, with the continuous advancement of industry technology, the "direct cooling + water cooling" method will become the main direction of market research and development.
In China, a small number of new energy vehicles such as JAC iEV7S use water cooling technology. JAC new energy pure electric SUV - iEV7S uses water cooling technology to control the temperature of the battery pack between 10-35 degrees Celsius. Even in an ultra-low temperature environment of minus 30 degrees Celsius, it can be charged normally without affecting the cruising range. The new generation of battery pack water cooling technology realizes rapid heating of the battery at low temperature. Under the conditions of -30℃ environment and -15℃ battery cell, the battery can be heated to above 10℃ within 40 minutes. At the same time, its excellent battery cooling performance meets the requirements of high-speed + fast charging continuous driving, and the battery temperature is controlled below 35℃.
