A comprehensive kinetic analysis of auto-ignition explosion characteristics of DME/NH3/H2/O2 blends and dilution effects on H2/O2

Abstract

This study analyzed the auto-ignition explosion limits of dimethyl ether (DME) blended with ammonia (NH₃) and hydrogen (H₂). The findings revealed that the auto-ignition explosion limit of pure DME exhibits negative temperature coefficient (NTC) behavior. As the NH₃ content increases, the auto-ignition explosion limit of DME transitions from a standard NTC response to a monotonic trend. In contrast, increasing the H₂ fraction causes the auto-ignition explosion limit of DME to evolve into a Z-shaped profile. A sensitivity analysis was performed to identify the key reactions affecting the auto-ignition explosion limits under varying pressures. By comparing the cool and hot flame limits of DME/NH₃, it was found that the pressure at lower turning point for hot flame limit is significantly higher than that of cool flame limit, while the changes at the upper turning points are less pronounced. Finally, the effects of carbon dioxide (CO₂) and nitrogen (N₂) on the auto-ignition explosion limit of the H₂-O₂ blend were analyzed, differentiating the physical and chemical effects of CO₂ and N₂ using the method of virtual gases. These findings provide a theoretical basis and guidance for the application of DME blended with zero-carbon fuels in combustion.