The hydraulic diameter design of the microchannel structure of liquid cooling battery pack liquid cooling plate has a crucial impact on the heat dissipation efficiency and overall performance of the battery pack.
First, the precise design of the hydraulic diameter requires full consideration of the thermal load of the battery pack. The heat generation rate of battery packs of different types, specifications and application scenarios varies greatly. For example, the battery pack of a high-performance electric vehicle will generate a lot of heat during high-rate charging and discharging. At this time, a smaller hydraulic diameter is required to increase the heat exchange area between the coolant and the channel wall, thereby improving the heat dissipation efficiency. The thermal distribution data under different working conditions can be obtained by thermal simulation analysis of the battery pack, and the approximate hydraulic diameter range that meets the heat dissipation requirements can be determined based on these data.
Secondly, the flow characteristics of the coolant must be taken into account. The hydraulic diameter directly affects the flow rate, pressure drop and flow state of the coolant in the microchannel. If the hydraulic diameter is too small, although the heat exchange area increases, it will cause the coolant flow resistance to rise sharply, requiring higher pump power to maintain circulation, increasing energy consumption and possibly affecting system stability. On the contrary, if the hydraulic diameter is too large, the flow rate will decrease and the heat exchange effect will deteriorate. Therefore, it is necessary to calculate the hydraulic diameter value that can ensure good heat transfer effect within a reasonable pressure drop range based on the selected coolant type (such as water, ethylene glycol aqueous solution, etc.) and its physical properties (viscosity, density, etc.) combined with the principles of fluid mechanics. For example, for water-based coolants with low viscosity, under certain flow requirements, a relatively small hydraulic diameter can be allowed to obtain a higher flow rate and heat transfer coefficient.
Furthermore, the feasibility of the manufacturing process is also a factor that must be considered when designing the hydraulic diameter. At present, microchannel processing technologies (such as photolithography, electrospark machining, precision stamping, etc.) have their own precision and size limitations. If the designed hydraulic diameter is too small, it may exceed the processing capacity of the current process, resulting in an increase in product scrap rate or a significant increase in manufacturing costs. Therefore, based on the hydraulic diameter calculated theoretically, it is necessary to make appropriate adjustments in combination with the actual processing technology level to ensure that industrial production can be achieved. For example, if a precision stamping process is used to manufacture a liquid cooling plate, the design of the hydraulic diameter needs to consider the manufacturing accuracy and minimum machinable size of the stamping die.
Finally, the long-term stability and reliability of the microchannel structure must also be considered. During the life cycle of the battery pack, the microchannel may face problems such as coolant corrosion, impurity blockage, and thermal stress caused by temperature changes. Smaller hydraulic diameters are more susceptible to these factors, resulting in channel blockage or structural damage. Therefore, a certain safety margin should be reserved during the design, corrosion-resistant materials should be used, channel shape should be optimized to reduce impurity deposition, and thermal stress analysis should be performed to ensure that the structure will not fail due to thermal expansion and contraction during long-term use, thereby achieving precise design of the hydraulic diameter and ensuring efficient and stable operation of the liquid cooling battery pack liquid cooling plate.
