Effects of mixing ozone on combustion characteristics of premixed methane/oxygen in meso-scale channels

Abstract

To investigate the effect of ozone on the combustion characteristics of premixed methane/oxygen in meso-scale channels, the flammability limits of the mixture with ozone are obtained experimentally, and the influence of ozone concentration on the near-limit combustion process is analyzed from the perspective of thermal effect and chemical kinetics effect by numerical simulation. Moreover, the changes of OH radicals, outer wall temperature and wall heat loss in mixture mixing ozone are compared. The results show that mixing ozone can significantly broaden the flammability limit of premixed methane/oxygen, increase the reaction temperature, and make the combustion zone move towards the inlet. Also, the chemical effect of ozone is more significant than its thermal effect. The concentration of OH and other free radicals are increased significantly by the interaction between the O atom produced by ozone decomposition and fuel molecules, which further accelerates the chain branching reaction, and enhances the whole combustion process. However, the total heat loss is increased by 4%–8% due to the sharp raising of radiation heat. Additionally, it is found that under non-stoichiometric conditions and low inlet flow rate, the increase of OH radical and outer wall temperature is more obvious, and the wall heat loss is also larger.