氨氢混燃着火及NOx排放特性数值模拟研究OA

[Objective]Replacing fossil fuel combustion with ammonia and hydrogen is an effective way to achieve large-scale carbon reduction.However,the ignition characteristics and NO,emission control law of ammonia-hydrogen co-combustion need to be further studied.[Methods]In this paper,the ammonia-hydrogen fuel with a total volume of 1 cm3 is taken as the research object,and the kinetic analysis of its co-combustion ignition characteristics is carried out by using Chemkin software.Firstly,the prediction performance of four different chemical reaction mechanisms for ammonia-hydrogen co-combustion was compared,and the Anand mechanism was selected as the basis for subsequent analysis of ammonia-hydrogen co-combustion.Secondly,the effects of pressure,temperature,equivalence ratio and hydrogen blending ratio on ignition delay time(IDT)and NOx were analyzed by control variable method.[Results]Studies have shown that the increase of pressure,temperature or hydrogen doping ratio can effectively shorten the IDT.Compared with the initial pure ammonia combustion condition of 0.1 MPa,1400 K,and equivalence ratio 1.0,IDT decreased from 57.3 ms to 13.0,7.3,and 5.5 ms,respectively,by increasing the pressure by 0.4 MPa,or increasing the temperature by 200 K,or adding 2.5％hydrogen.Compared with the initial condition,IDT decreased by 77.31％,87.26％,and 90.40％,respectively.The increase of temperature and hydrogen doping ratio increases the formation of NOx,which is because the addition of hydrogen promotes the formation of OH radicals,which in turn promotes the formation of NO.The increase of equivalence ratio significantly reduces the formation of NOx.On the basis of the initial condition,when the temperature is increased by 600 K,or 80％hydrogen is added,or the equivalence ratio is increased to 1.5,the NOx concentration is increased to 15 092 μL/L,14 005 μL/L,and decreased to 2 394 μL/L,respectively,compared with the initial condition of 11 138 μL/L,increased by 35.41％,and 28.67％,decreased by 78.51％.In general,the change of equivalence ratio has little effect on IDT in the range of 0.5～1.5,and the change of pressure has little effect on NOx concentration in the range of 0.1-2.0 MPa.[Conclusion]The research method in this paper can provide a reference for the theoretical simulation of the control of ammonia-hydrogen co-combustion conditions and the measures to reduce pollutants.