Effect of Plasma Chemistry on Activated Propane/Air Flames

We have developed a dielectric-barrier-discharge propane burner where propane is activated prior to being mixed with air and burned. In contrast to most work reported by others, combustion in our apparatus occurs away from the plasma region, thereby greatly reducing electric field effects, thus providing more insight into the role played by plasma chemistry. Flame flashback images were recorded as a function of the separation between the propane plasma and injected air, and the mixing length of the activated propane/air mixture. The lifetime of activated propane was found to be about 150 ms, while the lifetime of an activated propane/air mixture was measured to be about 300 ms. Using a gas-chromatograph diagnostic, H₂, CH₄, C₂ H₂, C₂H₄, and C₂H₆ were identified as the principal propane-discharge fragments, however, these are not the dominant species causing flame flashback behavior. The presence of reactive radical species is suggested to be a main factor governing flame flashback