An experimental investigation of refrigerant emergency spray on cooling and oxygen suppression for overheating power battery

The thermal safety of electric vehicle battery packs is attracting more and more attention. A research is conducted on emergency cooling and overheating control in this paper. The research work coupled with the direct cooling battery thermal management system proposes an open-loop emergency thermal safety management method that sprays refrigerant directly into the battery box to achieve emergency cooling, oxygen suppression, cutting off heat and combustion once the thermal runaway is about to occur. Three typical spray modes, which are continuous spray, fixed-interval intermittent spray, and non-fixed-interval intermittent spray, are analyzed respectively. Studies indicate that the refrigerant spray cooling has an obvious cooling effect, oxygen suppression performance on the high temperature overheating battery. Among them, continuous spray shows a better cooling capacity, but the oxygen suppression performance is inferior to intermittent spray. Intermittent sprays with various spray states have different degrees of influence on cooling, uniformity, and oxygen suppression performance, but a single spray pattern does not optimize the effects upon all aspects. Additionally, vent position also plays an important role in cooling and oxygen suppression characteristics. Therefore, overheating battery emergency refrigerant spray cooling has important reference significance for the design of battery package and thermal safety management system.