Experimental and modeling study on ignition delay times of dimethyl ether/ n -butane blends at a pressure of 2.0 MPa

In this study, the ignition delay times of dimethyl ether (DME)/n-C ₄H₁₀ fuel blends, neat DME, and neat n-C₄H ₁₀ diluted with argon were measured behind reflected shock waves. The experiments were performed in the temperature range of 1100-1600 K, at a pressure of 2.0 MPa, and equivalence ratios from 0.5 to 2.0. A latest kinetic mechanism NUIG Aramco Mech 1.3 was validated against the measured ignition data and used to conduct the chemical kinetic analysis. Results showed that different equivalence ratio-dependent behaviors were exhibited at different temperature regimes for DME, n-C₄H₁₀, and their blend. The ignition delay time of neat n-C₄H₁₀ was increased with an increase in the equivalence ratio. A strong inhibiting trend was exhibited at high temperatures. For the neat DME, however, an opposite influencing tendency from the equivalence ratio was presented in comparison to that on n-C ₄H₁₀. Ignition promotion becomes significant at relatively low temperatures. A 50% DME/50% n-C₄H₁₀ blend show a combined behavior of both n-butane and DME. Fuel reaction flux analysis, sensitive analysis, and mole fraction analysis were conducted for the understanding of the interaction between the ignition chemistries of DME and n-C₄H₁₀ at a pressure of 2.0 MPa.