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

The Korean Society of Mechanical Engineers (대한기계학회)
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Flame Structure and NOx Emission Characteristics in Laminar Partially Premixed CH4/Air Flames: Effects of Fuel Split Percentage and Mixing Distance

메탄/공기 층류 부분예혼합화염의 화염구조와 NOx 배출특성 : 연료분배율과 혼합거리의 영향

  • 정용기 (부산대학교 대학원 기계공학과) ;
  • 이종호 (부산대학교 대학원 기계공학) ;
  • 이석영 (부산대학교 대학원 기계공학) ;
  • 전충환 (부산대학교 기계공학과 기계기술연구) ;
  • 장영준 (부산대학교 기계공학부)
  • Published : 2004.07.01
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Abstract

In this paper, the study of effects of flow parameters on flame structure and NOx emission concentration was performed in co-axial. laminar partially premixed methane/air flames. Such (low parameters as equivalence ratio(${\Phi}$), fuel split percentage($\sigma$), and mixing distance(x/D$\_$i/) were defined as a premixing degree and varied within ${\Phi}$=1.36∼9.52, $\sigma$=50∼100, and x/D$\_$i/=5∼20. The image of OH$\^$*/ and NOx concentration were obtained with an ICCD camera and a NOx analyzer. The flame structure observations show a categorization of partially premixed flames into three distinct flame regimes corresponding to ${\Phi}$<1.7(premixed flame structure), 1.7<${\Phi}$<3.3(hybrid structure), and ${\Phi}$>3.3(diffusion flame structure existing a luminous sooting region) at $\sigma$=75%, and x/D$\_$i/=10. As o decreases from 100% to 50%, and x/D$\_$i/ decreases, nonpremixed flame structure appear at low equivalence ratio relatively. In addition, the measured emissions for NOx rise steeply from ${\Phi}$=1.7, to ${\Phi}$=3.3, then constants ${\Phi}$>4.76. NOx emissions decrease with increase the level of premixing level. In conclusion, the main effect on flame structure and NOx production was at first equivalence ratio(${\Phi}$), and next fuel split percentage($\sigma$), and finally mixing distance(x/D$\_$i/).

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References

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