Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
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An Investigation of the Heat Loss Model for Predicting NO Concentration in the Downstream Region of Laminar CH4/Air Premixed Flames

층류 CH4/Air 예혼합화염의 하류영역에서 NO 농도 예측을 위한 열손실 모델의 검토

  • Published : 2009.07.01
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Abstract

One-dimensional modeling of $CH_4$/air premixed flame was conducted to validate the heat loss model and investigate NOx formation characteristics in the postflame region. The predicted temperature and NO concentration were compared to experimental data and previous heat loss model results using a constant gradient of temperature (100 K/cm). The following conclusions were drawn. In the heat loss model using steady-state heat transfer equation, the numerical results using the effective heat loss coefficient ($h_{eff}$) of $1.0\;W/m^2K$ were in very good agreement with the experiments in terms of temperature and NO concentration. On the other hand, the calculated values using the constant gradient of temperature (100 K/cm) were lower than that in the experiments. Although the effects of heat loss suppress NO production near the flame region, a significant difference in NO concentration was not found compared to that under adiabatic conditions. In the postflame region, however, there were considerable differences in NO emission index as well as the contribution of NO formation mechanisms. In particular, in the range of ${\phi}\;{\geq}\;0.8$, the prompt NO mechanism plays an important role in the NO reduction under the adiabatic condition. On the other hand, the mechanism contributes to the NO production under the heat loss conditions.

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References

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