On the effect of different modeling assumptions and their impact on radiation heat transfer in a small gas-fueled furnace

Soot processes in a vertical methane-fueled furnace supplied with fuel through its primary inlet located at its bottom, and with air via two opposing horizontal air jets perpendicular to the direction of fuel supply, are studied numerically under different modeling assumptions. Results show that a complete decoupling of soot from the gas-phase computations leads to a significant overprediction of soot levels and consequently of heat radiated to the furnace walls. As the reactivity of the fuel with the oxidizer decreases, the overall amount of soot generated and, consequently, the amount of heat radiated to furnace walls also decreases. Simulating soot oxidation by using the Nagle-Strickland-Constable model leads to results that are to some extent comparable to those obtained when soot oxidation is represented by a combination of the Lee et al. model and a model that accounts for soot oxidation by OH radical. The results obtained when the standard k-ε model of turbulence is used are found to significantly differ from those attained when the modified version of the k-ε model proposed by Chen and Kim is employed.