Journal of the Korean Institute of Gas (한국가스학회지)

The Korean Institute of GAS (한국가스학회)
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Numerical Investigation of Low-pollution Combustion with applying Flue Gas Recirculation in Counterflow Flames: Part II. Analysis of NOx formation mechanism

대향류 화염에서 FGR이 적용된 저공해 연소의 수치적 해석: Part II. NOx 생성기구 분석

  • Cho, Seo-Hee (Department of Aerospace Engineering, Sunchon National University) ;
  • Kim, Gyeong-Mo (Department of Aerospace Engineering, Sunchon National University) ;
  • Lee, Kee-Man (School of Mechanical and Aerospace Engineering, Sunchon National University)
  • 조서희 (순천대학교 우주항공공학과) ;
  • 김경모 (순천대학교 우주항공공학과) ;
  • 이기만 (순천대학교 기계.우주항공공학부)
  • Received : 2020.06.24
  • Accepted : 2020.08.19
  • Published : 2020.08.31
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Abstract

Flue gas recirculation(FGR) is an effective combustion technique for reducing nitrogen oxides(NOx) and is applied in various fields of low-pollution combustion. Continuing the previous study, a numerical analysis was conducted to identify changes of flame characteristics and NOx formation mechanism with applying FGR technique in CH4/air premixed counterflow flames. NOx emitted was divided into four main reaction paths(thermal NO, prompt NO, N2H and N2O), showing relatively the production rate of NO with the recirculation ratio. As a result, thermal NO contributed greatly to the overall NO whereas the effect of N2H was minimal. In addition, emission index of NO was compared as the recirculation ratio increased by modifying the UC San Diego mechanism to examine the contribution of thermal NO.

배기가스 재순환(flue gas recirculation, 이하 FGR)은 질소산화물 저감에 효과적인 연소 기법으로 저공해 연소 분야에 다양하게 응용되고 있다. 이전 연구에 이어서 메탄/공기 대향류 예혼합화염에 FGR 기법 적용 시 나타나는 화염의 특성 변화 및 NOx 생성기구를 파악하기 위한 수치해석이 진행되었다. 배출되는 질소산화물(NOx)은 4가지 주요 반응경로(열적 NO, prompt NO, N2H 및 N2O)로 구분하여 배기가스 재순환율에 따른 각 NO 생성률을 상대적으로 나타내었다. 그 결과 열적 NO가 전체 NO 형성에 가장 크게 차지한 반면 N2H의 영향은 미미하였다. 또한, 열적 NO의 기여를 검토하기 위하여 본 연구에 사용된 반응기구(UC San Diego mechanism)를 수정하여 재순환율 증가에 따른 NO 배출지수(EINO)를 비교하였다.

Keywords

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