Experimental and Kinetic Study on the Cool Flame Characteristics of Dimethyl Ether

As one of the most promising alternative fuel to diesel engines, dimethyl ether plays a significant role in improving combustion efficiency and decreasing emissions, and an in-depth understanding of its combustion characteristics is the basis for efficient use. Although there are several chemical mechanisms that are used for kinetic modeling of dimethyl ether to reproduce its detailed information in the combustion process, the mechanism for cool flame is still imperfect, and the experimental data for ignition and flame is also very scarce. At the same time, low-temperature combustion associated with cool flame not only affects the safety of the engine but is also critical to the technologically advanced engine. In this work, both experimental and numerical methods are applied to study the cool flame characteristics of dimethyl ether. In a cylindrical reactor, the premixed dimethyl ether/air cool flame under different temperature, pressure, and equivalence ratio conditions was studied in detail, and the different ignition zones were obtained. Based on the commonly used dimethyl ether kinetic mechanism, the numerical simulation of the process of cool ignition and extinction limits were carried out. Also, the species concentration distribution and temperature profile were compared and analyzed. Combined with heat release and reaction path analysis, the ability of these mechanisms to describe the characteristics of dimethyl ether cool flame was evaluated, which contributes to the deep understanding of the cool flame process and the improvement of the mechanism in the cool flame zone.