Effects of methanol addition on the combustion characteristics of bio-diesel based counterflow nonpremixed flames

Abstract

With the improvement of combustion technology and the prominence of emission-related environmental concerns, the combined application of macromolecular unconventional fuels (bio-diesel) and alcohol ether fuels in engines is being considered. In this study, the effect of methanol addition on the combustion characteristics of methyl decanoate (MD)/air counterflow nonpremixed flames were investigated using numerical simulation. Two addition strategies of methanol were employed: premixing methanol into MD on the fuel side, and partially premixing of methanol on the air side. The corresponding flames are respectively double-flames with a rich premixed reaction zone and a nonpremixed reaction zone, or triple-flames with an additional lean reaction zone close to the air side. Results showed that, with the increased methanol addition, the global parameters of the double-flames and triple-flames were altered to different degrees. The both strategies of methanol addition can widen the flame thickness, and comparatively, the broadened flames with air-side addition of methanol were more obvious. The introduction of methanol showed little direct effects on the oxidation and pyrolysis of MD, and the key kinetic roles on the production of the active intermediates, such as OH and H in the flame domain. For both premixing strategies, the integral production of OH and H in the flames were increased, and the flames with the air-side methanol addition present the more significant production.