Forced Air-Cooling Strategies for Lithium-Ion Batteries Using Integral Wake Splitters and Flow Guide-Vanes

Thermal management of lithium-ion battery modules needs to be an integral part of the design process to guarantee that temperatures remain within a narrow optimal range. A well designed thermal management system will ensure good battery performance, safety and higher capacity. Many methods have been used, including air, liquid (direct and indirect), insulation, phase-change material, passive (ambient) or active (heaters, air-conditioning), or, a combination of these various approaches. In addition to regulating the module within a given temperature range, it is also important to minimize uneven distribution of temperature throughout the module. To not do so would decrease battery life cycle, and, charge and discharge performances.

This paper explores the use of surfaces extended into the near-wake of cylindrical lithium-ion cells, here termed integral wake splitters, and, of placing flow guide vanes also placed in the vicinity of the near-wakes. The numerical experiments are carried out in the Reynolds number range 10² - 10³. After initially simulating flow and thermal characteristics in the vicinity of an isolated Li-ion cell, which includes optimizing the wake splitter length (L) - to - cell diameter (D) ratio, and, the gap (W_g)  between flow guide vanes in the wake and their placement distance downstream of the cell (W_d) , the study expands to examining the effect of using cell arrangements on the thermal characteristics within a given module with optimized splitters and flow guide-vanes in place (Figure 1a and Figure 1b).

When using the integral wake splitters it is found that the local Nusselt numbers in the very near wake of a single cylindrical battery are depressed. Similar effects are found to occur when the battery cells are in formation. The use of flow guide vanes was found not to be as effective, but their use did contribute to a depressed Nusselt number.

Figure 1 Illustrations of the splitter plates (a) and flow guide vanes (b)