Evaluation of the Prediction Performance of FDS Combustion Models for the CO Concentration of Gas Fires in a Compartment

Bitna, Baek; Chang Bo, Oh; Chel-Hong, Hwang; Hong-Seok, Yun

doi:2018.32.1.7

Fire Sci. Eng. > Volume 32(1); 2018 > Article

Fire Science and Engineering 2018;32(1):7-15.
DOI: https://doi.org/10.7731/KIFSE.2018.32.1.007 Published online February 28, 2018.

구획실 내 가스연료 화재의 CO 농도에 대한 FDS 연소모델의 예측성능 평가

백빛나, 오창보, 황철홍, 윤홍석

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

Evaluation of the Prediction Performance of FDS Combustion Models for the CO Concentration of Gas Fires in a Compartment

Baek Bitna, Oh Chang Bo, Hwang Chel-Hong, Yun Hong-Seok

¹Department. of Safety Engineering. Pukyong National University
²Department. of Safety Engineering. Pukyong National University
³Department of Fire and Disaster Prevention, Daejeon University
⁴Department of Fire and Disaster Prevention, Daejeon University

요약

구획실 내 프로판 가스화재에 대해 Fire Dynamics Simulator (FDS)를 이용한 수치계산을 수행하고 실험과의 비교를 통해 적용된 연소모델 예측성능을 평가하였다. 검토된 연소모델은 FDS v5.5.3의 혼합분율 연소모델과 FDS v6.6.3의 Eddy Dissipation Concept (EDC) 모델이며, EDC 모델에서 화학반응기구는 1-step Mixing Controlled, 2-step Mixing Controlled, 3-step Mixing Controlled 및 Mixing Controlled 반응과 유한화학반응이 혼합된 3-step Mixed 반응을 적용하였다. 구획실 내부의 온도에 대해서는 각 연소모델들 간의 예측성능 차이는 그다지 크지 않음을 확인하였다. 연소모델 차이에 의한 $O_2$와 $CO_2$ 농도에 대한 예측성능 차이보다는 CO에 대한 예측결과 차이가 크게 나타났다. CO 농도에 대해서는 EDC 3-step Mixing Controlled 모델이 가장 높게 예측하며 혼합분율 연소모델은 실험보다는 낮게 예측하였다. EDC 3-step Mixed 모델이 가장 예측성능이 좋았지만 EDC 2-step Mixing Controlled 모델도 충분히 합리적인 수준으로 예측하고 있음을 확인하였다. EDC 1-step Mixing Controlled 모델에 기존에 제안된 CO 수율을 적용할 경우 CO 농도에 대해서 너무 과소 예측하며 CO 예측 정확도를 높이기 위해 수율을 높이면 $CO_2$ 농도에 대한 합리적인 예측이 어려워지는 문제점이 있었다.

Abstract

The prediction performance of combustion models in the Fire Dynamics Simulator (FDS) were evaluated by comparing with experiment for compartment propane gas fires. The mixture fraction model in the FDS v5.5.3 and Eddy Dissipation Concept (EDC) model in the FDS v6.6.3 were adopted in the simulations. Four chemical reaction mechanisms, such as 1-step Mixing Controlled, 2-step Mixing Controlled, 3-step Mixing Controlled and 3-step Mixed (Mixing Controlled + finite chemical reactions) reactions, were implemented in the EDC model. The simulation results with each combustion model showed similar level for the temperature inside the compartment. The prediction performance of FDS with each combustion model showed significant differences for the CO concentration while no distinguished differences were identified for the $O_2$ and $CO_2$ concentrations. The EDC 3-step Mixing Controlled largely over-predicted the CO concentration obtained by experiment and the mixture fraction model under-predicted the experiment slightly. The EDC 3-step Mixed showed the best prediction performance for the CO concentration and the EDC 2-step Mixing Controlled also predicted the CO concentration reasonably. The EDC 1-step Mixing Controlled significantly under-predict the experimental CO concentration when the previously suggested CO yield was adopted. The FDS simulation with the EDC 1-step Mixing Controlled showed difficulties in predicting the $CO_2$ concentration when the CO yield was modified to predict the CO concentration reasonably.

Key Words: Carbon Monoxide, Combustion Model, Fire Dynamics Simulator (FDS), EDC Model, Mixture Fraction Model