Journal of the Korea Academia-Industrial cooperation Society (한국산학기술학회논문지)

The Korea Academia-Industrial cooperation Society (한국산학기술학회)
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NOx Formation Characteristics on Heat Loss Rate for CH4/Air Premixed Flames in a Perfectly Stirred Reactor

완전혼합 반응기에서 CH4/Air 예혼합화염의 열손실율에 따른 Nox 생성특성

  • Hwang, Cheol-Hong (Building and Fire Research Laboratory, NIST) ;
  • Lee, Kee-Man (School of Aerospace Engineering, Sunchon National University) ;
  • Kum, Sung-Min (School of Mechanical & Automotive Engineering, Halla University)
  • 황철홍 (미국립표준기술연구소 건물화재실험실) ;
  • 이기만 (순천대학교 항공우주공학과) ;
  • 금성민 (한라대학교 기계자동차공학부)
  • Published : 2009.07.31
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Abstract

The effect of heat loss rate on NOx formation of $CH_4/air$premixed flame were examined numerically in a perfectly stirred reactor. The following conclusions were drawn. Under the adiabatic wall condition, an increase in the residence time causes a remarkable increases in NOx emission. Under the heat loss conditions, however, NOx decreases significantly as the heat transfer coefficient and residence time increase. As the heat loss rate increases, Thermal NO mechanism and Re-burning NO mechanism play an important role in the NOx reduction, but Prompt NO mechanism and $N_2O$-intermediate NO mechanism lead to the increase in NOx production. Although the NOx formation is actually related to complex NOx mechanism with the changes in the heat transfer coefficient and residence time, it was found that NOx concentration can be represented by independent Thermal NO mechanism. From these results, new NOx correlation combined with the heat loss rate and residence time was suggested for predicting the NOx concentration in a practical $CH_4/air$premixed combustor.

완전혼합 반응기에서 외부로의 열손실이 $CH_4/air$예혼합화염의 NOx 생성특성에 미치는 영향을 수치해석으로 검토하였다. 주요 결과로서, 단열조건에서 NOx는 체류시간에 따라 급격히 증가하는 반면에, 열손실이 고려될 때 열전 달 상수와 체류시간의 증가에 따라 NOx 저감현상이 뚜렷하게 발생하였다. 민감도 해석을 통해 열손실율이 증가함에 따라 Thermal NO 기구와 Re-burning NO 기구는 NOx 저감에 크게 기여하는 반면, Prompt NO 기구와 $N_2O$-경유 NO 기구는 오히려 NOx 증가에 기여함을 확인하였다. NOx 생성기구는 열전달 상수 및 체류시간의 변화에 따라 매우 복합한 특성을 갖지만, NOx 농도는 독립된 Thermal NO 기구에 의해 표현될 수 있었다. 이를 통해 실용 $CH_4/air$예혼합 연소기에서 NOx 농도를 예측할 수 있는 열손실율과 체류시간을 조합한 새로운 NOx 상관식이 도출되었다.

Keywords

References

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