Effects of blending 2,5-dimethylfuran and dimethyl ether to toluene primary reference fuels: A chemical kinetic study

Abstract

In the present work, renewable oxygenates 2,5-dimethylfuran (DMF) and dimethyl ether (DME) are considered as alternatives to fossil fuels for gasoline engines. The effects of blending DMF and DME on the combustion of gasoline surrogate are numerically studied. The gasoline surrogate is toluene primary reference fuel (TPRF) mixtures containing iso-octane, n-heptane, and toluene. Two skeletal mechanisms are proposed for the analysis: mechanism A with 504 species and 4212 reactions and mechanism B with 153 species and 740 reactions. These mechanisms are validated against a wide range of experimental data on ignition delay times and 1-D flames. The main findings of the present work are: 1) The ignition inhibiting effect of DMF dominates over the promoting effect of DME at 750 K and 25 bar when the total mole fraction of DMF and DME is less than 20 %. On the contrary, DME augments ignition with greater strength than the inhibition effect of DMF at 825 K and 25 bar. These observations are made for equimolar mixture of DMF and DME blended with TPRF in varying proportions. 2) The laminar burning velocity change stays within 10% of TPRF-air values for 50% TPRF/25%DMF/25%DME-air mixture for 0.6 ≤ φ ≤ 1. 6. 3) DME mitigates additional soot emission caused by DMF blending with TPRF. 4) For the first time in literature, it is shown that the laminar burning velocity and the maximum slope of OḢ mole fraction in the stoichiometric flames vary linearly with the research octane number (RON) for TPRF-air mixtures.