Hydrogen-Air- Exhaust Gas Mixture Combustion And Emission Characteristics Study

Hydrogen combustion faster than gasoline quickly, making higher flame temperature than that of the gasoline engine, producing large amounts of NOx emissions, controlling NOx emission has become the main direction in the study of hydrogen internal combustion engine. In this paper, studied the characteristics of hydrogen-air premixed laminar combustion.Firstly, constructed the premixed laminar combustion test platform. According to gas partial pressure law, equivalence ratio and stoichiometric ratio, wrote the hydrogen-air-diluent gas mixed gas pressure calculation formula. A set of programs for accurate radius of spherical diffusion flame is written by MATLAB software.As the flame is affected by the ignition energy at the initial stage, the flame propagation is not satisfied with the theory of the Markstein in the end of the development stage. So the data of flame radius in the range of Sn-α is fitted by 6~25mm. With the increase of the equivalence ratio, the flame speed of the without stretched laminar flow increases firstly and then decreases, and the peak value is reached when the equivalence ratio is 1.8: 24.29m/s and 5.55m/s, respectively.Finally, the conditions of the different initial temperature, different nitrogen doping ratio and different waste gas mixed have been studied with hydrogen air pre mixed laminar combustion characteristics. With the increase of initial temperature, hydrogen air pre mixed combustion without stretched laminar flame propagation speed increases, laminar burning velocity increases; with the increase of initial temperature, the flame temperature increases, but the rate of increase is not very obvious; the H/H+OH /H+OH+O max mole fractions in reaction zone have great relevance with laminar flame burning velocity. NO increases with the increase of the initial temperature. With the increase in the ratio of mixed gas of nitrogen doped, stretched laminar flame propagation velocity and combustion rate showed a downward trend; with the increase of nitrogen doping ratio, the slope of the line of Sn-α tends to zero, indicating that the flame becomes unstable. Because nitrogen doping ratio increased actually decreases the mixed gas of hydrogen content. With the increase of nitrogen doped ratio, the gas temperature has been sharply decreased, which has caused the NO concentration decrease obviously. With the increase of the waste gas mixture, the flame speed decreased, the strength rate of the initial stage of the flame is decreased. The NO concentration was correlated with the flame temperature and the flame burning rate, and it decreased with the increase of the mixing quantity of the gas mixture.