scholarly journals A Study on Equivalence-Ratio Dependence of Minimum Ignition Energy Based on Initial Burning Velocity

2013 ◽  
Vol 79 (805) ◽  
pp. 1839-1847 ◽  
Author(s):  
Eiichi MURASE ◽  
Osamu MORIUE ◽  
Hideki HASHIMOTO ◽  
Isei MATSUZAKI
2011 ◽  
Vol 133 (3) ◽  
Author(s):  
Eliseu Monteiro ◽  
Abel Rouboa

In the currently reported work, three typical mixtures of H2, CO, CH4, CO2, and N2 have been considered as representative of the producer gas (syngas) coming from biomass gasification. Syngas is being recognized as a viable energy source worldwide, particularly for stationary power generation. However, there are gaps in the fundamental understand of syngas combustion characteristics, especially at elevated pressures that are relevant to practical combustors. In this work, constant volume spherical expanding flames of three typical syngas compositions resulting from biomass gasification have been employed to measure the laminar burning velocities for pressures ranges between 1.0 and 20 bar tanking into account the stretch effect on burning velocity. Over the ranges studied, the burning velocities are fit by a functional form Su=Su0(T/T0)α(P/P0)β; and the dependencies of α and β upon the equivalence ratio of mixture are also given. Conclusion can be drawn that the burning velocity decreases with the increase of pressure. In opposite, an increase in temperature induces an increase of the burning velocity. The higher burning velocity value is obtained for downdraft syngas. This result is endorsed to the higher heat value, lower dilution and higher volume percentage of hydrogen in the downdraft syngas.


A model is proposed for the ignition of quiescent multidroplet fuel mists which assumes that chemical reaction rates are infinitely fast, and that the sole criterion for successful ignition is the generation, by the spark, of an adequate concentration of fuel vapour in the ignition zone. From analysis of the relevant heat transfer and evaporation processes involved, ex­pressions are derived for the prediction of quenching distance and minimum ignition energy. Support for the model is demonstrated by a close level of agreement between theoretical predictions of minimum ignition energy and the corresponding experimental values obtained using a specially designed ignition apparatus in which ignition energies are measured for several different fuels, over wide ranges of pressure, mixture composition and mean drop size. The results show that both quenching distance and mini­mum ignition energy are strongly dependent on droplet size, and are also dependent, but to a lesser extent, on air density, equivalence ratio and fuel volatility. An expression is derived to indicate the range of drop sizes over which the proposed model is valid.


2018 ◽  
Vol 13 (6) ◽  
pp. 50
Author(s):  
Gleb V. Grenkin ◽  
Alexander Yu. Chebotarev ◽  
Valeri I. Babushok ◽  
Sergey S. Minaev

The optimization procedure was developed to derive the global kinetic parameters using experimental dependence of burning velocity on the equivalence ratio. The simple model of laminar premixed flame propagation with assumed constant parameters was used to demonstrate the features of the suggested procedure. The suggested method allows finding optimal parameters for the defined functional dependence of the reaction rate on the temperature and reactant concentrations. The dependence of combustion adiabatic temperature on equivalence ratio is assumed to be known from the flame equilibrium calculations. The global kinetic parameters of combustion reaction were determined for methane, ethylene and propane mixtures with air on the basis of experimental data on burning velocity as function of the equivalence ratio. The calculated overall kinetic parameters are compared with parameters obtained by other methods within similar global model.


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