Effect of Radiation Models on the Suppression Limits in Counterflow Methane/Air Diffusion Flames

Sun-Yeo, Mun; Jae-Ho, Cho; Cheol-Hong, Hwang; Chang Bo, Oh; Won-Hee, Park

doi:2014.28.3.20

Fire Sci. Eng. > Volume 28(3); 2014 > Article

Fire Science and Engineering 2014;28(3):20-28.
DOI: https://doi.org/10.7731/KIFSE.2014.28.3.020 Published online June 30, 2014.

대향류 메탄/공기 확산화염에서 복사모델이 소화한계에 미치는 영향

문선여, 조재호, 황철홍, 오창보, 박원희

¹대전대학교 소방방재학과
²대전대학교 소방방재학과
³대전대학교 소방방재학과
⁴부경대학교 안전공학과
⁵한국철도기술연구원

Effect of Radiation Models on the Suppression Limits in Counterflow Methane/Air Diffusion Flames

Mun Sun-Yeo, Cho Jae-Ho, Hwang Cheol-Hong, Oh Chang Bo, Park Won-Hee

¹Department of Fire & Disaster Prevention, Daejeon University
²Department of Fire & Disaster Prevention, Daejeon University
³Department of Fire & Disaster Prevention, Daejeon University
⁴Department of Safety Engineering, Pukyong National University
⁵Korea Railroad Research Institute

요약

대향류 메탄/공기 확산화염에서 복사모델이 소화한계에 미치는 영향이 수치적으로 검토되었으며, 수치결과의 검증을 위하여 기초실험이 병행되었다. 소화약제로는 $N_2$와 $CO_2$가 고려되었으며, 다른 정확도를 갖는 복사모델 OTM과 SNB에 따른 소화농도의 차이가 검토되었다. 주요 결과로서, $N_2$가 첨가된 경우, 복사모델의 정확도에 따라 소화농도의 큰 차이가 발생되지 않는다. 그러나 강한 복사효과를 갖는 $CO_2$가 낮은 신장율의 화염에 첨가되었을 때, SNB와 같은 예측 정확도가 높은 복사모델이 고려되어야 한다. 특히 연료에 첨가된 $CO_2$의 경우 복사모델 SNB와 OTM에 의한 소화농도는 차이를 갖게 된다. 따라서 소화농도 예측을 위해서는 수치해의 정확도와 계산시간을 고려한 합리적인 복사모델의 선택이 필수적이라 할 수 있다.

Abstract

Effect of radiation models on the suppression limits in counterflow $CH_4$/air diffusion flame was numerically investigated with fundamental experiments for the numerical validation. $N_2$ and $CO_2$ were considered as extinguishing agents. The differences in extinguishing concentration between OTM and SNB radiation models which have different accuracy levels were examined. As a result, there is no considerable difference in extinguishing concentration for the $N_2$ dilution as the radiation models with different accuracy levels were used. As the $CO_2$ having strong radiative effect was diluted in the low strain flames, however, the radiation model with high predictive accuracy such as SNB should be used. In particular, the $CO_2$ dilution in fuel stream leads to the significant difference in extinguishing concentration between OTM and SNB models. Therefore, it is necessary that the radiation model should be reasonably chosen with the consideration of numerical accuracy and computational time for the prediction of extinguishing concentration.

Key Words: Counterflow diffusion flame, Extinguishing concentration, Suppression limit, Radiation model