Numerical study on the effects of ozone addition on the development of laminar premixed flames and emissions for methane and propane in a co-flow configuration

Abstract

In this study, a numerical investigation on the effects of ozone addition on the laminar premixed flame development and emissions formation of carbon monoxide (CO) and nitrogen oxides (NOx) for methane and propane in a co-flow burner is presented. Simulations for the reacting mixtures with the addition of ozone concentrations of 3810 ppm and 6000 ppm were performed at atmospheric pressure, ambient temperature of 298 K and equivalence ratios (φ) of 0.8, 1.0 and 1.3. Based on the simulation results, ozone improved the flame development, where the flame temperatures for methane/propane were raised by 42 K (maximum difference). Besides, the formaldehyde (CH2O) and hydroxyl (OH) mass fractions were also increased and subsequently elongated the stand-off distances for methane/propane by 12%. The laminar burning velocities for methane/propane were accelerated by 8.7%, which were contributed by the higher rates of fuel oxidation due to the increased ozone concentration. Although the CO and NOx mass fractions for the ozone enhanced methane/propane flames were deviated by a maximum difference of 29%, the effect of ozone on these emissions were found varied according to the fuels and φ values.