Structure and working principle of liquid cooling plate

The battery module has certain requirements for the liquid-cooling plate. First of all, the heat dissipation power is large, which can quickly take away the heat generated by the module and prevent the sharp rise of temperature; Secondly, it has high reliability. When the vehicle is walking on the road, the battery pack in working condition should be tested in various environments, such as vibration, impact, high and low temperature. The working voltage of the power battery pack is often hundreds of volts, and the leakage of coolant will become a very serious problem. Even if the coolant with good insulation performance is used, it will immediately reduce its insulation performance after encountering the doping of external substances, Cause certain safety risks, therefore, the sealing reliability of the liquid cooling plate is very important; Moreover, the heat dissipation design should be accurate to avoid excessive temperature difference in the system. The working temperature has a very important impact on the performance and aging of the battery; Finally, there is a requirement for weight. At present, the battery pack pays attention to lightweight, which requires that each component in the package be lightweight. If the liquid cooling plate takes up too much weight, it will directly affect the energy density of the battery module, which is unacceptable.

In view of the above problems, in the design process of liquid-cooled plate, the aluminum substrate buried copper pipe is generally used, that is, the aluminum substrate is milled with computer numerical control technology, and then the bent copper pipe is pressed onto the aluminum substrate with a press, and then brazed and welded. This design, on the one hand, plays the role of weight reduction and cost control due to the lightweight of aluminum, on the other hand, makes full use of the high thermal conductivity of copper tubes. Finally, two inlets and outlets are set to inject the corresponding liquid refrigerant, usually water or a mixture of water and organic alcohol (alcohol can prevent water from freezing at low temperature), and the water pump controls the circulation of the liquid. Water or the mixture of water and organic alcohol is used as liquid cooling radiator because in physics, the thermal conductivity and specific heat capacity of water are much larger than that of air, the heat conduction speed is fast, and the temperature rise is slow, so water is an ideal heat dissipation medium. In the battery pack, because according to the different environment, water is easy to freeze in the low temperature environment, which is very harmful to heat dissipation. To solve this problem, the mixture ratio of water and organic alcohol is generally used as the refrigerant, and the results are well verified.

The working principle of the liquid-cooling plate is that the excess heat generated by the operation of the battery is transferred by contacting with the surface of the plate-type aluminum device. The liquid-cooled system uses the characteristics of large liquid flow heat transfer coefficient to transfer high heat by liquid flow, and is finally taken away by the cooling liquid passing through the internal flow channel of the device.