A novel liquid cooling battery thermal management system with a cooling plate based on biomimetic fractal channels

An effective battery thermal management system (BTMS) is necessary to quickly release the heat generated by power batteries under high discharge rate and ensure the safe operation of electric vehicles. Inspired by the biomimetic structure in nature, a novel liquid cooling BTMS with a cooling plate based on biomimetic fractal structure was proposed. By developing the physical model of the BTMS, numerical calculations were conducted to analyze the impacts of the structural parameters of the cooling plate and the inlet velocity of the coolant on the thermal performance of the batteries. The results showed that the cooling plate can meet the heat dissipation requirements of high temperature uniformity for the batteries under high discharge rate, especially under the extreme uniform channel distribution mode for the adjacent fractal branch at the same level. Moreover, the increase of the group number of fractal branches can improve the cooling capacity of the cooling plate and reduce the pressure drop of the coolant. The increase of the level number of channels, the length ratio, and the inlet velocity of the coolant can enhance the cooling capacity. However, these methods of enhancing heat transfer require more pump power consumption. When the group number of fractal branches is 4, the level number of channels is 3, the length ratio is 1 and the inlet velocity of the coolant is 0.5 m/s, the BTMS can control the maximum temperature and maximum temperature difference of the batteries under 4C-rate discharge within 31.68 °C and 4.15 °C, respectively. Finally, orthogonal test was conducted on four factors: the group number of fractal branches, the level number of channels, the length ratio and the inlet velocity of the coolant. The results showed that the level number of branches is the most important structural parameter.