Ignition delay times of iso-butane activated by DME under various equivalence ratios in the shock tube

The ignition delay time of the high cetane number dimethyl ether (DME), high octane number i-butane, and their binary blends were investigated in a shock tube over the temperature range of 1091-1797 K, pressures of 2-10 atm, and equivalence ratios of 0.5-2.0. The LLNL iso-Octane Model and the DME sub-set of the Aramco3.0 Model were assembled together to reproduce the ignition delay behavior of the binary blends. Chemical kinetic analyses were conducted to understand the interplay between DME and i-butane at high temperatures. The ignition delay of DME and i-butane show the opposite equivalence ratio dependence under the current conditions. The promoting effect of DME addition on the ignition delay of i-butane becomes more significant as the equivalence ratio increases. The research result shows that there is no significant fuel to fuel interactions between DME and i-butane in the present conditions. The high reactivity of DME and its rapid accumulation of the free radicals lead to the promoted auto-ignition of i-butane.

Automated summary

The ignition delay of DME and i-butane shows opposite equivalence ratio dependence at high temperatures, and the addition of DME promotes the ignition delay of i-butane, especially as the equivalence ratio increases. The research results indicate no significant fuel to fuel interactions between DME and i-butane under the present conditions, with the high reactivity of DME leading to the accelerated auto-ignition of i-butane.