Experimental and modeling study of premixed atmospheric-pressure dimethyl ether-air flames

Chemical species profiles have been measured at atmospheric pressure for tw o dimethyl ether (DME)-air flat flames having fuel/air equivalence ratios o f 0.67 and 1.49. The samples, obtained with an uncooled quartz probe, were analyzed by either gas chromatography or Fourier transform infrared (FTIR) spectroscopy for CH4, C2H2, C2H4, C2H6, C3H8, DME, CO, CO2, O-2, CH2O, and formic acid. a pneumatic probe calibrated at a reference position in the bu rned gas by a radiation-corrected thermocouple provided temperature profile s for each flame. Species profiles for two methane-air flames with equivale nce ratios and cold-gas flow velocities similar to those of the DME flames were also obtained for comparison to the DME results, Mole fractions of C-2 product species were similar in DME and methane flames of similar equivale nce ratios. However, the CH2O mole fractions were 5-10 times larger in the DME flames. These experimental profiles are compared to profiles generated in a computer modeling study using the best available DME-air chemical kine tic mechanism. The Appendix presents photographs of DME, methane, and ethan e diffusion flames. These results show that, while DME produces soot, its y ellow flame luminosity is much smaller than that of an ethane flame at the same fuel volume flow rate, consistent with the low soot emission rate obse rved when DME is used as a diesel fuel.