On the Three-Stage Explosion Characteristics of Diethyl Ether-Oxygen Mixtures

In this article, the three-stage explosion limits of diethyl ether (a typical alternative fuel with a high cetane number and high energy density) are taken as the research object. A comprehensive and in-depth analysis of the double negative temperature coefficient (NTC) behavior of the cool flame region and hot ignition region, through the detailed kinetic analysis, have been carried out. The results show that with the increase of the equivalence ratio, the double NTC phenomenon becomes more remarkable. In very lean conditions, such as the equivalence ratio of less than 0.5, the boundary between the first NTC region and the second NTC region becomes obscure, and a deeper single NTC phenomenon is formed as these two NTC regions merge. The whole explosion limit curve shifts to higher pressure conditions with the increase of the addition of inert gas. The NTC phenomenon in the moderate temperature region becomes more significant and the boundary between these two NTC regions is more obvious. In addition, the hot flame explosion limit also shows such two NTC response. The heat release rate (HRR) profile exhibits three-stage, two-stage, single-stage ignition, or non-ignition depending on the initial conditions. To elucidate the differences in the ignition process between the different explosion limit regimes, the sensitivity and reaction pathway analyses are performed. This study not only provides insight into the oxidation characteristics of ether fuels, but also provides theoretical support for high-performance engines.