Experimental and modeling study of the effect of ethanol and MTBE on the oxidation of PRF90 in low pressure premixed laminar flame

Two premixed laminar flames of PRF90 (Primary Reference Fuel, iso-octane:n-heptane is 9:1) blended with ethanol and MTBE (Methyl Tert-Butyl Ether) respectively were studied, using molecular-beam sampling technology combining with tunable synchrotron VUV (Vacuum Ultra-Violet) photoionization mass spectrometry. Mole fraction profiles of species including reactants, intermediates and products were derived from the measurement. A detailed mechanism for high temperature oxidation under low pressure of the fuels mentioned above was developed based on USC-Mech II and each fuel sub-mechanism. The modeling result shows that the radical pool is affected by the change of additives and this leads to a slight change of PRF (Primary Reference Fuel) consumption paths. Both experimental and modeling results show that species with carbon number more than four and species with high unsaturation degree are not affected by the change of additives, while alkadienes are a little higher and acetaldehyde is lower in PRF90/MTBE flame, comparing with those in the PRF90/ethanol flame. In addition, the experimental result shows methanol and other carbonyl compounds including formaldehyde, acetone and butanone have higher concentrations in PRF90/MTBE flame.