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The global energy demand enhances the environmental and operational benefits of natural gas as an energy alternative, due to its composition, mainly methane (CH4), it has low polluting emissions and benefits in energy and combustion systems. In the present work, the laminar burning velocity of methane was determined numerically and experimentally at two pressure conditions, 0.85 atm and 0.98 atm, corresponding to the city of Medellín and Caucasia, respectively, located in Colombia. The environmental conditions were 0.85 atm, 0.98 atm, and 295 ± 1 K. The simulations and experimental measurements were carried out for different equivalence relations. Experimental laminar burning velocities were determined using the burner method and spontaneous chemiluminescence technique, flames were generated using burners with contoured rectangular ports to maintain laminar Reynolds numbers for the equivalence ratios under study and to reduce the effects of stretch and curvature in the direction of the burner's axis. In general, the laminar burning velocity fits well with the numerical results. With the results obtained, a correlation is proposed that relates the laminar burning velocity with the effects of pressure, in the form SL = aPb, where a and b are model constants. Sensitivity analysis was performed using the GRI-Mech 3.0 mechanism which showed that the most sensitive reaction was H+O2 = O+OH (R38). Additionally, it was found that the reactions H+CH3 (+M) = CH4 (+M) (R52), 2CH3 (+M) = C2H6 (+M) (R158), and O+CH3 = H+CH2O (R10) dominate the consumption of CH3 which is an important radical in the oxidation of methane, this analysis is carried out for equivalence ratios of 0.8 and 1.0, and atmospheric pressures of 0.85 atm and 0.98 atm. [ABSTRACT FROM AUTHOR]

This paper presents a study of CH 4 /Air/H 2 /O 2 premixed laminar flames using a ratio of H 2 /O 2 equal to 2/1. This gas mixture represents the products of the electrolysis of water. To date, only numerical analysis has been carried out on these kinds of blends and using H 2 /O 2 percentages of only up to 10% by volume. Furthermore, there have been no reports of experimental analysis or possible flame instabilities associated with the enrichment of the mix with H 2 /O 2 . In this study, the effect of adding water electrolysis products on the laminar burning velocity and stability of lean premixed methane/air flames is studied for different percentages of H 2 /O 2 (10 and 25) in the lean combustion regime, which is relevant for most engineering applications. The results show that a higher addition of H 2 /O 2 to methane increases the laminar burning velocity. In particular, at Φ = 0.75, intrinsic instabilities are observed for mixtures with 25% of H 2 /O 2 in methane. With the addition of H 2 /O 2 , the laminar flame thickness decreases and the growth rate increases. Hence, the addition of H 2 /O 2 to a premixed natural gas flame enhances the hydrodynamic instabilities. [ABSTRACT FROM AUTHOR]