Experimental and theoretical investigation of ethyl methyl carbonate/air flames: Laminar burning velocity and cellular instability at elevated pressures

Ethyl methyl carbonate (EMC) gained great attention because of its advantages shown in practical applications both as a blend with conventional oil-derived liquid fuels, and as a solvent being used in Li-ion cell electrolyte compositions. Thus, a better knowledge of the combustion characteristics of EMC/air premixed flames is necessary, which has not yet been well-explored. Towards this goal, the laminar flame propagation of EMC/air mixture was investigated using a constant-volume combustion chamber at the initial pressures of 1, 2, 5 and 8 atm, with the unburned temperature of 423 K and the equivalence ratios ranging from 0.7 to 1.5. A recently established chemical kinetic mechanism of EMC by Takahashi et al. (Combust. Flame 2022) was adopted for the theoretical prediction, which accurately reproduced the measured LBVs at 1-5 atm; however, it underpredicted the LBVs for the lean flame condition at 8 atm. According to the flame instability analysis, the increase in pressure leads to the elevated hydrodynamic instability and the decreased critical radius of spherical premixed flame. Meanwhile, the rich flames of EMC/air had the smaller critical Peclet numbers and suffered the more severe thermal-diffusive instabilities.

Automated summary

Ethyl methyl carbonate (EMC) has been extensively studied for its potential applications in liquid fuels and Li-ion cell electrolytes. The combustion characteristics of EMC/air premixed flames were investigated in a constant-volume combustion chamber, showing pressure-dependent flame instability and thermal-diffusive instabilities for lean and rich flames, respectively. A chemical kinetic mechanism accurately predicted the flame propagation at lower pressures but underestimated the flame velocity at higher pressures for lean mixtures.