Experiment Study On PAHs Formation In Laminar Diffusion Flame Of Anisole And Benzyl Alcohol

Lignin is a typical second-generation biomass fuel.Its utilization is one of the effective ways to solve the energy crisis,air pollution and climate change.PAHs(polycyclic aromatic hydrocarbons)are not only a kind of organic pollutant with great harm,but also the precursor of soot.In order to realize the utilization of lignin,it is necessary to explore the combustion characteristics and typical pollutant generation characteristics of its main components,anisole and benzyl alcohol.Previous studies have explored the performance of anisole and benzyl alcohol and the formation characteristics of some pollutants based on engine bench test.However,due to the stability of liquid fuel and the large spectral overlap between LIF(Laser Induced Fluorescence)signal of PAHs and LII(Laser-Induced Incandescence)signal of soot,no scholar has realized the laminar diffusion flame of anisole and benzyl alcohol The generation characteristics of PAHs.In this paper,a novel laser diagnosis technology combining LII and LIF is proposed.The difference between LIF signal lifetime of PAHs excited by PAHs and LII signal lifetime of soot is used to overcome the similarity of the two spectral bands,so as to realize the measurement of PAHs in flame.In this study,n-heptane with similar cetane number and performance as diesel fuel was used as the base fuel.The effects of different combustion conditions,such as fuel flow rate,carrier gas flow rate,and the addition of anisole and benzyl alcohol on the formation characteristics of PAHs in laminar diffusion flame were investigated.The experimental results show that the addition of anisole and benzyl alcohol can promote the formation of PAHs obviously,but the difference of molecular structure makes the promotion effect of benzyl alcohol stronger;the total amount of PAHs in the flame will first increase and then decrease with the increase of fuel flow rate,but it will first decrease and then increase with the increase of air flow rate,the increase of carrier gas flow rate will inhibit the formation of PAHs;the pressure will increase The effect of anisole and benzyl alcohol on PAHs formation is only slightly affected by the increase of pressure.On the one hand,the research in this paper provides ideas for the design and improvement of power machinery using biomass fuel,on the other hand,it also provides a reference for the research and improvement of PAHs and soot formation mechanism,and also lays a theoretical foundation for the utilization of lignin,which is mainly composed of anisole and benzyl alcohol.