Effect of variable cross-section liquid cooling pipes on thermal management performance enhancement of lithium-ion batteries

In this work, variable cross-section liquid-cooled vertical pipes with cavities and ribs are used for battery thermal management. The results show that the vertical arrangement of liquid cooling pipes is better in terms of heat dissipation performance, parasitic power consumption, and lightweight degree, and it is more easily able to meet the design requirements of a battery pack with a maximum temperature of 40 °C and a maximum temperature difference of 5 °C, compared with the horizontal arrangement of liquid cooling pipes. For specific liquid cooling pipe structures, the pipes with cavities have the best heat dissipation performance and the lowest pump parasitic power consumption, while the ribbed pipes have the highest pressure loss value and their performance is most sensitive to the variation in mass flow rate and pipe inner diameter. Finally, based on entropy theory, a secondary design of vertical pipes with cavities is carried out. The results indicate that increasing the height of the cavity can reduce the irreversible heat transfer losses and improve the heat transfer performance by breaking the boundary layer, meanwhile, the maximum temperature of the battery pack can be reduced by 1.1K while the maximum temperature difference is enhanced by 0.64K.