Flow pattern maldistribution and manipulation during two-phase cooling for power batteries: A critical review

As the one of key components for electric vehicle and renewable energy systems, power battery is always confronted with the issue of thermal safety. It is therefore necessary to design an adequate thermal management solution. Two-phase cooling based on flow boiling has proved its unique advantage of strong heat dissipation capability in cooling applications of small-scale electronic devices due to the utilization of latent heat, and it is considered as one of the promising successors for conventional battery thermal management system (BTMS) based on single-phase liquid cooling. However, the popularization of two-phase direct cooling for power battery is limited due to the difficulty on the maintenance of thermal uniformity, resulted from the strict challenge in the organization of two-phase flow during boiling. In order to highlight the major concerns on two-phase cooling BTMS, and provide directions for future investigations, this review is organized based on the consideration of physical mechanisms of two-phase cooling. The flow patterns during flow boiling are reviewed to show their relationship with heat transfer. Studies on flow maldistribution during two-phase flow are then summarized to show the complexity of two-phase flow organization. Further introduction is presented on the current manipulation methods on flow pattern based on various principles. Based on the reviews on previous studies, future research directions on two-phase cooling BTMS are outlined, while methods to achieve uniform flow pattern distribution is suggested as the possible solution towards optimal thermal uniformity for two-phase cooling BTMS.