Venting characteristics, combustion mechanism, and safety assessment for AlH3 dust induced low concentration hydrogen explosion in connected container

AlH 3 , as a metal hydride with high hydrogen storage capacity, has enormous application potential. However, the solid-gas multiphase system formed by its hydrogen release significantly increases its explosion risk. Nevertheless, the characteristics of low-concentration hydrogen explosions triggered by it have not been sufficiently studied. In the paper, the explosion and venting characteristics of AlH 3 dust induced the low concentration H 2 were evaluated by a self-built connected container. Combined with molecular dynamics simulation, the combustion mechanism was explored. Further, the effectiveness of the NFPA 68 standard and EN 14491 standard was discussed. The consequences indicated that with the increase in dust concentration, the maximum explosion pressure, pressure rise rate, and venting flame velocity advanced first and then dropped under confined and venting conditions, reaching the peaks at a concentration of 750 g/m 3 . Under confined conditions, both the pressure peak and the maximum pressure rise rate were recorded as 1.05 MPa and 80.07 MPa/s, respectively. Under venting conditions, these two parameters dropped to 0.55 MPa and 44.23 MPa/s. The type of venting flame was divided into flame length decreasing gradually until extinguished and flame multiple oscillations. For the venting safety assessment of AlH 3 dust, the calculation of NFPA 68 standard was more accurate. The research results have enriched the theoretical framework of multiphase explosion dynamics, can reduce the risk of explosion accidents in industrial processes, and at the same time provide practical significance for the safe and large-scale application of AlH 3 . • Explosion pressure and venting pressure of AlH 3 induced H 2 were contrasted. • Venting flame propagation characteristic of AlH 3 induced H 2 were analyzed. • Combustion reaction mechanism of AlH 3 induced H 2 were established. • Applicability of the NFPA 68 standard and EN 14491 standard was discussed.