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A computational study on two-dimensional laminar premixed combustion has been conducted. A working model was developed that fully coupled a comprehensive chemical kinetic mechanism with computational fluid dynamics in the commercial software program FLUENT. The physical model for the simulations consisted of an adiabatic tube with a constant velocity inlet and an atmospheric pressure outlet. For all cases, the flame waves were shown to be stabilized by the developing boundary layer near the inlet.
The combustion of methane with air was studied in depth and compared with the combustion of three different biofuels: landfill gas and two varieties of syngas. Additionally, combustion with a mixture of O2 and CO2 as an oxidizer was proposed as a way to facilitate carbon dioxide capture and sequestration. Flames produced by this combustion technique were then compared with traditional combustion oxidized with air.
Results for methane combustion compared closely with experimental work and one-dimensional numerical work in predicting flame shape, laminar flame speed, and flame thickness. It was shown that the presence of the tube wall affected the flame thickness, but not the laminar flame speed, at sufficiently high inlet velocities. The results from the combustion of landfill gas showed that its laminar flame speed is lower than methane but that its flame shape is similar in nature to that of methane. Simulations of syngas combustion proved to be troublesome for the computational model, which struggled to converge to reasonable solutions, indicating that more work is needed with the numerical modeling method. Results from combustion simulations with the O2/CO2 oxidizer revealed that the flame characteristics were affected by the lower thermal diffusivity of the oxidizer, resulting in lower laminar flame propagation speeds and thicker combustion waves. The flame shape remained similar to combustion oxidized with air.