Theoretical Assessment of the Sodium Pool Fire's Burning Rate in an Open Environment

ABSTRACT The burning rate of sodium pool fires is a critical parameter for assessing fire development and associated hazards. Because of the competitive mechanism between the combustion products Na 2 O and Na 2 O 2 in metallic sodium, and the fact that most products do not leave the sodium pool system in the form of smoke, traditional methods for calculating burning rates based on mass loss are not applicable. This study establishes a simplified burning rate model based on the fuel evaporation model. By conducting sodium pool fire experiments with diameters ranging from 4 to 12 cm in an open environment, the relationship between pool temperature and flame temperature under stable combustion conditions was obtained as a function of pool diameter and incorporated into the theoretical model to evaluate the pool fire burning rate, thereby deriving the heat release rate. The research indicates that the burning rate of sodium pool fires increases with pool diameter but gradually approaches a quasi‐saturation state due to the limited conversion rate of oxidation products. Under open‐air atmospheric conditions and within the small‐scale extrapolation framework, the sodium pool fire burning rate approaches a quasi‐saturated value of approximately 0.01391 kg m −2 s −1 at an effective pool diameter near 22 cm during the steady combustion stage, corresponding to a heat release rate of approximately 4.75 kW.