# The Period of Ignition Delay for Methane-Air Mixture with Hydrogen and Ethylene Additives
## 6 Conclusions  
Based on the comparison of the calculated and experimental data, it is shown that the most satisfactory coincidence of ignition delay period values for mixtures of methane + hydrogen + ethylene with air or oxygen at initial pressures P = 1-8 bar and temperatures T = 900-1100 K can be achieved in the case of using kinetic model NUIGMesh 1.1, which includes 493 components and 2716 reactions.  
It is shown that the values of the ignition delay period for the mixtures under consideration are in the range from 0.004 to 0.5 s. According to the data obtained, the ignition delay period of a fuel based on methane with additions of hydrogen and ethylene (up to 10 % in total by mass) can be reduced by up to 3 times relative to the ignition delay period of pure methane in air. It is shown that the minimum values of the ignition delay period were obtained for a mixture of methane with hydrogen. Replacing the hydrogen additive with ethylene slightly increases the ignition delay period (up to 15%), but it is still significantly lower than the ignition delay period for pure methane in air. The greatest effect of a relative increase in the reactivity of the mixture is observed at low pressures (1-2 bar) and temperatures (<1000 K). In the case of ignition of mixtures of methane + hydrogen + ethylene in oxygen, chemical reactions are accelerated relative to ignition in air by almost an order of magnitude. In this case, the effect of hydrogen and ethylene additives is somewhat enhanced at low pressures (up to 4%).  
The practical impact of the results obtained in this work is that it is found to correlate and validate different experimental data. The results of the work make it possible to estimate the ignition delay time for fuel on a methane-hydrogen-ethylene gas mixture in air.  
This work represents a first step in the direction of investigating the ignition delay time for mixtures. The data produced will be used for future experimental work with new  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{3}{c}{**Mass Fraction**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} & \multicolumn{1}{c}{**Mode**} \\ \hline
**CH4** & **H2** & **C2H4** & **Nb 1** & **Nb 2** & **Nb 3** & **Nb 4** & **Nb 5** & **Nb 6** \\ \hline  
\hline \hline \end{tabular}
\end{table}
Table 7: The period of the ignition delay of a mixture of methane + hydrogen + ethylene with oxygen for different modes at \(\alpha\) = 2.0.  
conditions and compositions of the mixture. Further research into the ignition delay time of the methane-based fuel-air mixture suggests:  
* reinforcement of the results of kinetic mechanisms by experimental data in some modes;
* the use of other additives to reduce the ignition delay time of the fuel-air mixture;
* the development of its own kinetic mechanism based on the obtained results, which allows the satisfactory description of the generalized data.  
Conceptualization, V.S.Z.; Formal analysis, A.Y.V.; Writing--original draft, S.V.G., A.V.N., and V.M.E.; Writing--review & editing, L.S.Y. and K.Y.A. All authors have read and agreed to the published version of the manuscript.  
This research was funded by The Ministry of Science and Higher Education of the Russian Federation Agreement No 075-15-2020-806 dated 29 September 2020.  
The authors declare no conflict of interest.