Study of the explosive behaviour of NH3/H2/air mixtures

Ammonia/hydrogen fuel mixture is considered to be a new type of sustainable and environmentally friendly energy. However, their explosive properties are not well understood. This study investigated the explosion of NH3/H2/air fuel mixture in a 1.67-litre constant-volume combustion chamber using hydrogen ratios (H2 = 15, 20, 25, and 30%), equivalence ratios (phi = 0.8-1.4), starting temperatures (Ti = 298, 363, and 428 K), and pressures (Pi = 1, 2, and 3 bar). The explosivity of NH3/H2/air was characterized using the maximum explosion pressure (Pmax), maximum pressure rise rate (dP/dtmax), and deflagration index (KG). Also, the maximum heat release rate (HRRmax) and heat loss were used to account for variations in heat generated by the explosion. The findings indicate that Pmax decreases with increasing temperature but Pmax, dP/dtmax, and KG increase with an increase in pressure. Overall, an increase in pressures, hydrogen ratios, and equivalence ratio enhances the explosion severity, but the pressure has a significant effect on the explosion severity. Furthermore, a cubic polynomial provides a superior match to the correlations between the Pmax, dP/dtmax, KG, and HRRmax and equivalence ratio. This study deeply explores the safe use mechanism of NH3/H2 mixed fuel and provides an essential reference for the safe application of NH3/H2 mixed fuel.