Experimental and Modeling Study on Ignition Delay Times of Dimethyl Ether/Propane/Oxygen/Argon Mixtures at 20 bar

Ignition
delay times of dimethyl ether (DME)/propane/oxygen/argon mixtures
at a pressure of 20 bar were measured in a shock tube at different
DME blending ratios (0, 20, 50, 80, and 100%), equivalence ratios
(0.5, 1.0 and 2.0), and temperatures (1100–1500 K). Validations
of chemical kinetic models were made using available chemical kinetic
models. A modified chemical model (Mod Mech C5) was proposed, and
it can predict well the experimental ignition delay times and activation
energies of pure propane, pure DME, and their blends. Both experimental
and numerical results show that, with the decrease of the temperature,
the logarithmic ignition delay time is increased linearly and activation
energy is decreased slightly. With the increase of the equivalence
ratio, the ignition delay time is increased for propane but decreased
for DME. The ignition delay time is decreased with the increase of
the DME blending ratio, and the reduction rate is increased with an
increase in the equivalence ratio. Sensitivity analysis and radical
pool analysis were performed to interpret the promoting effect of
DME addition on the ignition of DME/propane mixtures.