Overpressure rise rate prediction method for hydrogen-air explosions in vented silos

The widespread adoption of hydrogen faces a significant challenge due to the risk of unintentional explosions during its production and storage. In the design of explosion-resistant structures, the overpressure rise rate is a critical parameter. This study aims to predict the overpressure rise rate in vented silo structures during hydrogen-air cloud explosions using a simplified approach. Over 80 scenarios of premixed hydrogen-air mixture explosions in various silo configurations were simulated using a numerical model developed with FLACS. The results show that the explosion process can be divided into three distinct stages based on flame behaviour, with the second stage contributing the majority of the overpressure and displaying linear growth. Building on these findings, a physical model for flame deflagration was developed by combining simulation results with theoretical derivations. A prediction method for forecasting the overpressure rise rate in vented silos during hydrogen-air explosions was derived, showing a strong correlation with numerical simulation results (R 2 = 0.98), and demonstrating higher accuracy than the NFPA 68 standard. The model was also adjusted to account for variations in initial temperature. These findings offer valuable insights for the prediction of overpressure rise rates in hydrogen-air mixtures, aiding in the design of explosion-resistant structures. • A physical model for flame propagation is devised to elucidate the overpressure rise rate of hydrogen explosion. • The proposed prediction method yields a strong correlation with an R 2 value of 0.98 and surpasses NFPA 68 in accuracy. • It also accommodates varying vent conditions and initial temperatures.