The Effect Of H₂O/CO₂ On NO/CO Foermation In Metnane Flame

The contradiction between energy demand and environmental pollution increases the development and utilization of clean energy,becoming the dominate energy,such as natural gas and non-fossil energy,gradually applied in power machine engine and thermal power generation,as the result,the pollutant emission must be solved.The method is effective that diluent in the methane flame is used to decrease pollution emission,based on FGR.The paper add H₂O and CO₂ to fuel side and oxidant side in methane flame,to analyzing the effect of diluents on burning temperature and components,as well as the update reaction pathways in methane diffusion flame.The paper separates the physical and chemical effect on methane flame by replacing the chemical molecule with virtual molecule?FH₂O and FCO₂?.To improve the computational efficiency,the paper reduces the detailed mechanism of methane burning.Firstly,the important reaction is obtained by sensitivity analysis from GRI-mech 3.0,which is closely related to main species.Then,remove the independent from detailed mechanism by Direct Graph Method,based on contribution rate to main species,and verify the effectiveness of reduced mechanism.Based on the above work,the paper uses the reduced mechanism to research the effect on burning temperature and pollution emission from diluents?H₂O and CO₂?,by change the diluent sort,diluting position,and chemical properties of diluents.The results show that H₂O diluent in fuel side has better effect on the pollution emission reduction,the NO emission reduces 24%,and CO emission reduces 16%when the diluent rate is 30%to fuel volume.The effect from the physical properties of H₂O diluents reaches 0.5⁰.8 to the effect from the physical and chemical properties.So the physical properties of additive H₂O have great influence on pollution emission,but the effect of chemical properties cannot be neglected.The chemical effect of H₂O diluent to reduce pollution emission by reduce the radical mole fraction of CH,H,O,OH.CO₂diluents have the same effect on NO emission,but increase CO emission,When the additive proportion is 30%,the inhibiting effect of the additive H₂O on NO is 2.15 times higher than that of CO₂.When adding CO₂ and H₂O in methane flame simultaneously,the effect of the two is not simple sum of the effect from CO₂ and H₂O respectively,when the diluent is H₂O,NO emission is the lowest,but when the diluent volume of CO₂ and H₂O is equal,the diluents can effectively reduce methane burning temperature.