Study on Explosion Characteristics of Ammonia/Dimethyl Ether/Air with Different Mixed Compositions

Abstract

The blend of ammonia (NH3) and dimethyl ether (DME) is a promising renewable and clean fuel. This work studies the basic explosion characteristics of NH3/DME/air with varying equivalence ratios (from 0.6 to 1.8) and DME fractions (from 0.2 to 1). Three essential parameters, i.e., explosion pressure (P max), explosion time (t c), and maximum pressure rise rate ((dP/dt)max), were experimentally obtained, and the heat loss during the explosion was quantitatively analyzed. Besides, the heat release characteristics and critical flame radius of destabilization in the explosion process were analyzed using the detailed NH3/DME reaction mechanism. The results showed that adding DME to the mixture can significantly increase the P max, increase the (dP/dt)max, and shorten the t c. The heat loss during the NH3/DME/air explosion mainly presents a negative correlation with the explosion intensity, as reflected by (dP/dt)max and t c. In addition, at stoichiometric ratios, the elementary reaction R12: H + OH + M = H2O + M contributes most to the total heat release of the NH3/DME/air explosion, while the NH3- or DME-related reactions subdominate the total heat production. Adding DME reduces the critical flame radius, causing the flame to enter an unstable state earlier, which is mainly dominated by the hydrodynamic effect.