Abstract

소화약제의 국소방출방식 개념이 적용될 수 있는 대향류 확산화염을 대상으로 <TEX>$CO_2$</TEX> 소화약제의 소화기구를 재조명하기 위한 연구가 시도되었다. 이를 위해 연료 또는 공기류에 <TEX>$CO_2$</TEX>가 첨가된 낮은 총괄신장율의 <TEX>$CH_4$</TEX>/air 대향류 확산화염이 상세반응을 이용한 수치해석을 통해 검토되었다. 첨가된 <TEX>$CO_2$</TEX>를 포함한 복사 참여 화학종의 복사 열손실을 고려하기 위하여 optically thin model(OTM)이 적용되었다. 주요 결과로서, 공기류에 첨가된 <TEX>$CO_2$</TEX>의 소화농도 예측결과는 문헌에 보고된 실험결과를 적절하게 예측하고 있으나, 연료류에 첨가된 경우 다소 과소 예측된 결과를 확인하였다. 소화효과에 대한 정량적 분석을 위하여 가상의 소화약제의 개념이 도입되었다. <TEX>$CO_2$</TEX> 소화효과의 분석을 통해 총괄신장율(<TEX>$a_g$</TEX>)에 따른 순수 희석효과, 복사 열손실 및 열용량에 의한 열적효과 그리고 <TEX>$CO_2$</TEX>의 연쇄반응 억제를 통한 화학적 효과의 정량적 기여도를 구체적으로 확인할 수 있었다. The suppression mechanisms of carbon dioxide (<TEX>$CO_2$</TEX>) as a representative fire suppression agent were revisited using a counterflow diffusion flame which could be applied the concept of a local application system. To end this, the low strain rate <TEX>$CH_4$</TEX>/air counterflow diffusions with <TEX>$CO_2$</TEX> addition in either fuel or oxidizer stream were examined numerically using detailed-kinetic chemistry. Radiative heat loss due to radiating gas species including <TEX>$CO_2$</TEX> added was considered by the optically thin model (OTM). As a result, the critical <TEX>$CO_2$</TEX> volume fractions in the oxidizer stream required to extinguish the flame were in good agreement with the experimental data reported in the literature, while somewhat under-prediction was observed with <TEX>$CO_2$</TEX> added in the fuel stream. The surrogate agents were adopted to estimate the quantitative contribution with changing in global strain rate (<TEX>$a_g$</TEX>) on the flame extinguishment among pure dilution effect, thermal effects including radiation heat loss and chemical effect due to the <TEX>$CO_2$</TEX> fire suppression agent.

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