Compatibility of Fuels and Radicals Found in Plasma Jets for Improved Premixed Combustion

Abstract

We examined the compatibility of radicals contained in plasma jets to fuels through ignition and combustion tests for dimethyl ether (DME)/air and methane (CH4)/air mixtures with oxygen (O2) and nitrogen (N2) as the plasma torch feedstocks. The experiment showed that the DME/air mixture was ignited/combusted with less plasma jet (P.J.) power than the CH4/air mixture and that the O2 P.J. is more effective than the N2 P.J., with a more distinct difference in effectiveness for the CH4/air mixture in contrast to the DME/air mixture. Plasma jets with fewer feedstock flow rates were more effective, presumably due to the greater amount of radical production under the conditions tested. Numerical estimation on the amount of radicals and ignition delay time demonstrates that the superiority of the O2 P.J. is not necessarily only due to the effectiveness of the O radicals, but also due to the fact they were produced easier and with less power, and that the effect and behavior according to amount is different for fuels. This is most likely because they depend on the reaction mechanism of each mixture, all of which match well with the experimental results.