Study On Combustion Characteristics Of Premixed Combustion Of Ammonia-hydrogen Carbon-free Fuel

The environmental pollution,greenhouse effect and energy crisis caused by traditional fossil energy have aroused widespread concern worldwide.Energy conservation and emission reduction have become the key concerns of the whole society.As carbon-free clean renewable energy,hydrogen and ammonia have the potential to replace traditional fossil energy,meet large-scale energy consumption needs,and reduce greenhouse gas emissions.In order to provide theoretical support for the design of next-generation ammonia-hydrogen carbon-free burners and the application of ammonia-hydrogen fuel,it is necessary to conduct in-depth research on the combustion characteristics of ammonia-hydrogen mixed fuel.In this paper,a burner and an experimental system for the research of ammoniahydrogen laminar premixed flame are designed.The effects of fuel equivalent ratio,hydrogen ratio,total flow,initial intake temperature on flame blow-out limit,hydrogen lean-limit,and lean/rich limit combustion characteristics are explored through experiments.The results show that mixing hydrogen in the premixed gas can improve the flame stability at low flow rates.The greater the proportion of hydrogen,the wider the lean/rich limit range of the flame;the greater the total flow,the greater the flame the lean/rich limit range is narrower;the formation of ball-like flame and cap-like flame is observed near the lean limit.In addition,it is found that increasing the initial intake air temperature can expand the lean/rich limit range.On the CHEMKIN simulation platform,based on the Pre-Mixed Burner Stagnation Flame model,Mei,Konnov,and Glarborg mechanisms are used to simulate the hydrogen lean-limit and lean/rich limit.The results show that the experimental and simulation results have the same changing trend,and the Konnov mechanism has the best performance when simulating the ammonia-hydrogen flame combustion limit.The effects of ammonia-hydrogen fuel equivalent ratio,hydrogen ratio,and total flow on flame photothermal combustion characteristics are analyzed by thermocouple,ICCD camera,infrared thermal imaging camera.The results show that the flame chemiluminescence intensity increases(FCI)with the increase of the equivalent ratio and the total flow,and decreases with the increase of the hydrogen ratio;the flame maximum temperature(FMT)decreases with the increase of the hydrogen ratio,FMT increases first and then decreases with the increase of the equivalence ratio,and reaches the maximum value when the equivalence ratio is 1.2.Individually changing the hydrogen ratio or the total flow,FCI can be regarded as an indicator of flame temperature.The higher the FCI,the higher the flame temperature.Through experiments and simulations,this paper explores the combustion limit characteristics,the chemiluminescence characteristics and the flame temperature characteristics of the ammonia-hydrogen flame.The relevant conclusions provide a theoretical basis for understanding the combustion behavior of ammonia-hydrogen fuel and the design of the burner.