| Natural gas is a naturally existing hydrocarbon mixture of hydrocarbons and its volume content of 96.16%are methane.Methane mixed hydrogen fuel is considered to be one of the most effective ways to improve methane combustion efficiency.In this paper,based on the mature and detailed chemical dynamic combustion mechanism GRI-MECH3.0,with the help of the OPPDIF module of CHEMKIN software,the simulation of methane/air one-dimensional laminar flow diffusion dilution flame transport characteristics and its flame dynamics mechanism under the condition of hydrogen blending are studied.;Concerned about the effects of the chemical and diffusion properties of added hydrogen on methane/air hedging diffusion flame,the main purpose of which is to provide a new method to understand the chemical kinetic mechanism of combustion of mixtures containing hydrogen.The research contents and main results of this paper are as follows:?1?This paper studies the effect of adding different concentrations of hydrogen to methane/air hedging diffusion flame on flame characteristics,and the addition of hydrogen will cause the flame reaction to occur in the lower temperature area and improve the combustion efficiency of methane/air flame.At the same time,through the concrete analysis of the reaction steps in the flame process,it is found that primitive reaction R38?H+O2<=>O+OH?and R86?OH+H2<=>H+H2O?are one of the main reactions to the generation of active free radicals,and H and OH are the most critical active free radicals for methane/hydrogen/air premixed gas combustion reaction.When the addition of hydrogen leads to a significant increase in the yield of H and free radical OH,the consumption rate of OH increases,and the chemical properties of hydrogen itself promote the mass generation of free radicals H,O and OH in the Flame of Mars,and the concentration of active free radicals determines the reaction rate of CH4.?2?the effects of different hydrogen blending ratios on methane hedging diffusion flame,and by conceptualizing hydrogen with virtual low conduction properties,the fictitious hydrogen has the same thermodynamic and chemical characteristics as normal hydrogen,which does not have diffusion transfer capability,and adds this fictitious hydrogen to methane/air hedging diffusion flame.The influence of the change of its variables on the structure and main products in the flame was observed.This non-conductive fictitious hydrogen can help to detect the effect of hydrogen conduction characteristics in hydrogen mixed with methane/air flame,and a series of effects on the addition of flame,taking into account only the thermodynamic and chemical properties contained in hydrogen itself.After data analysis,it is found that the chemical properties of fictitious hydrogen?HH?itself can continue to carry out the basic oxidation combustion reaction of CH4 in flame,but compared with the real hydrogen,the decrease of its transitivity will reduce the production rate and full combustion rate of CH4,and the maximum flame temperature of the lack of conductive fictitious hydrogen is lower than that of the original flame.And its flame thickness decreases correspondingly,because the heat generated by the combustion of hydrogen itself is lower than the heat generated by methane combustion,and the high efficiency conductivity of hydrogen can promote the high efficiency of the flame,increase the transmission distance and transmission speed of the flame,and improve the combustion efficiency of the flame.And the chemical properties of hydrogen have obvious effects on the formation of CH3,C2H2 and C3H8,and their conductivity plays a major role in promoting the formation of CH3OH and CH2O.The addition of hydrogen will reduce NO production efficiency,which is mainly due to the high efficiency conductivity of hydrogen,the lack of conductive HH addition to reduce the generation of NO,and the mixing of any type of hydrogen has little effect on the chemical reaction pathway of No in the process of methane combustion reaction. |
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