Reduced Kinetic Mechanism For Common Hydrocarbon Fuel In Micro-scale Combustion

With the development of Micro Electro Mechanical System(MEMS), the demand for the power supply unit with high power and long life becomes more and more urgent. The power system based on the micro-scale combustion is getting more and more popular for its high energy density, low cost and low pollution. The focus of the micro power system is micro-scale combustion. The reduced mechanisms which can reflect the characteristics in micro-scale combustion are needed in order to do the simulation in micro-scale combustion fast and accurately.The reduced mechanisms are mainly simplified according to the characteristics of the conventional combustion. However, the conventional combustion is different from the micro-scale combustion in reaction scale and residence time. Based on this background, the detailed mechanisms for common hydrocarbon fuels are simplified in this article according to the characteristics of micro-scale combustion.The significance of simplification and the simplification method are introduced at the first part of the paper. The DRGEP method and the SA method are mainly introduced here. The detailed mechanisms for common hydrocarbon fuel are simplified using these methods based on the characteristics of micro-scale combustion.Firstly, the detailed mechanism for hydrogen/oxygen was simplified with different simplification methods. The 12-step mechanism and the 17-step mechanism were obtained using the different methods. These reduced mechanisms as well as the detailed mechanism were used in the PSR model for calculation. The results showed that the calculation results of the 17-step mechanism were more close to that of the detailed mechanism.Secondly, the detailed mechanism for methane/oxygen was simplified. The DRGEP method and the SA method were used for simplification of the detailed mechanism GRI-Mech3.0. The 10 species, 19-step mechanism was obtained using the former method. The PSR model was used to investigate the application range of the reduced mechanism. The results showed that the reduced mechanism could predict the temperature and the concentration of the key components over the equivalence ratio range of 0.5~1.6. The 19 species, 38-step mechanism was obtained using the latter method. The maximum error of the simulation results in the PSR model and the premixed laminar flame model between the detailed mechanism and the reduced mechanism was less than 10%. The PSR model was used to investigate the application range of the 38-step mechanism. The result turned out that the reduced mechanism was adaptive to the combustor with the volume from 0.1cm3 to 0.8cm3. In the equivalence ratio range from 0.5 to 1.5, the reduced mechanism was consistent with the detailed mechanism.Thirdly, the SA method was used for the simplification of the methane/air mechanism. The application range of the reduced mechanism was verified using the method similar with that of the methane/oxygen reduced mechanism.The reduced mechanism was verified through the experiments and the simulation. The reduced mechanism was used for simulation in Fluent. The maximum error between the simulation results and the experimental data was less than 4%. The reduced mechanism was further proved to be correct for that the simulation results were consistent with the experimental data.Finally, the application of the reduced mechanism in the catalytic combustion was investigated. The 17-step reduced mechanism for hydrogen/oxygen was used in the catalytic reaction coupled with the surface reaction mechanism in the PSR model. And the 38-step methane/oxygen reduced mechanism was also used in the catalytic combustion coupled with the surface reaction mechanism in the PSR model. The simulation results of the reduced mechanism were compared with that of the detailed mechanism. The result showed that the temperature and the key component of the reduced mechanism were consistent with that of the detailed mechanism. And the maximum error of the simulation results between the reduced mechanism and the detailed mechanism was less than 6%.