• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.7
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• pp.504-512
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• 2008

The characteristics of nonpremixed oxy-fuel flame in a multi-jet burner were experimentally and numerically investigated. The overall flow rate of fuel and oxygen was fixed, and the oxygen feeding ratio (OFR) was varied by 0.25, 0.5, and 0.75. The results of numerical simulation were compared with the measured results which are temperature profile and direct flame observation. The probability density function (PDF) model was applied accounting to the description between turbulence and chemistry, and standard ${\kappa}-{\varepsilon}$ model was used for turbulent flow field. Equilibrium assumption is very reasonable due to fast chemistry of the oxy-fuel combustion. Thus, the equilibrium calculation based on Gibbs free energy minimization was guaranteed to generate the solution of the oxy-fuel combustion. The result was obtained by numerical simulation. The predicted radial temperature profiles were in good agreement with the measured results. The flame length was shorten and was intensified with the decrease of OFR because the mixture of fuel and oxidizer are fast mixed and burnt. The maximum temperature became lower as the OFR increased, as a consequence of large flame surface area.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.409-416
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• 2010

The use of oxy-fuel combustion and flue gas recirculation (FGR) for $CO_2$ reduction has been studied by many researchers. This study focused on the characteristics of oxy-fuel combustion and the effects of $CO_2$ addition from the point of view of oxygen feeding ratio (OFR) and the position of $CO_2$ addition in order to reproduce an FGR system with a triple concentric multi-jet burner. Oxy-fuel combustion was stable at all OFRs at a fuel flow-rate of 15 lpm, which corresponds to an equivalence ratio of 0.93; however, the structure and length of the flame varied at different OFRs. When $CO_2$ was added in oxy-fuel combustion, various stability modes such as stable, transient, quasistable, unstable, and blow-out were observed. The temperature in the combustion chamber decreased upon $CO_2$ addition in all conditions, and the maximum reduction in temperature was below 1800 K. $CO_2$ concentration with respect to height varied with the volume percent of $CO_2$ at the nozzle tip.