Prediction of toxic species in fire

大多数火灾死亡与高温闪燃后火灾产生的有毒产物的远程运输有关，特别是一氧化碳（CO） [S1, S2]。目前，数值工具可以有效地描述这些有毒产物的运输，但无法准确预测火灾中产生的数量，因此缺乏来源[S2， S3]。为了扩展消防安全工程（FSE）方法的范围，并为从业者提供更有效的工具，迫切需要一种强大的、经过充分验证的方法，以全面解决问题，从而完成整个链条，并提供真正的预测能力[S3]。这将为许多新的应用打开大门，包括火灾取证，以协助确定死亡原因，补充昂贵的全面火灾测试，并最终在建筑设计中，并可能改变FSE方法的应用和利用。至关重要的是，任何这样的方法都可以被消防社区有效地利用，因此它必须在计算上要求不高（以便它可以在顾问通常使用的计算机上运行），并且必须有效地适应现实世界火灾的具体要求，即涉及非常广泛的长度范围的大型建筑场景，以及多种且通常复杂的燃料来源。其中对有毒产物产量的重要贡献可能来自气相的复杂形成过程，也可能直接来自固相，通过可燃边界材料的热解[S2]。这里提出了一种先进的方法，其中每个过程都可以有效地适应，基于每个感兴趣的化学物种的输运方程的解。本提案的重点是CO预测，但该方法可以在未来扩展到包括其他有毒物种。要解决的关键研究问题是如何最有效地实现化学源项闭合，这是湍流燃烧系统建模的基本挑战。将研究不同的方法，包括基于使用简化的准层流表达式直接求解耦合物种平衡方程的基本方法，以及一种更复杂的方法，即小火焰建模方法的扩展。如文献[S4]所述，这些预测将以现有方法为基准，这些方法依赖于传统的有毒产物产量的小火焰表示和简单涡流破裂概念方法的扩展。新方法将根据真实火灾场景的相关实验数据进行验证，以充分测试新建模策略的通用性[S2， S3, S5]。考虑到计算资源和准确性的基本竞争需求，将编制关于方法开发的详细建议。参考文献========S1。Babrauskas， V, Levin, b.c, Gann， R. G, Paabo， M., Harris, Jr .， R. H., Peacock， R. D.和Yusa， S.（1991）火灾危害分析的毒性效价测量，Special Pub. 827， NIST, Dec 1991S2。Pitts， W.M.（1995）全球等效比概念和围场火灾中一氧化碳的形成机制，Prog。能源燃烧。科学。，第21卷，第197-237S3页。Purser， D. & Purser， J.（2003）在消防安全工程中纳入火灾化学和毒性的可能性，BRE客户报告202804,2003.26。Hyde， S.M.和Moss， J.B.（2003）模拟污染隔间火灾中的CO产量，第7期。计算机协会。《消防安全科学》，第395-406页。Smith, d.a., Marshall， N., Shaw， K., & Colwell， S.（2001）与单一燃烧项目测试相关的大规模火灾性能，Proc. 9th Int。国际会议，第531-542页

Most fire deaths are associated with the remote transport of toxic products produced in hot post-flashover fires, and with carbon monoxide (CO) in particular [S1, S2]. Currently, numerical tools are effective at describing the transport of these toxic products, but incapable of accurately predicting the quantities generated in a fire - thus the source is missing [S2, S3]. In order to extend the scope of fire safety engineering (FSE) methods, and provide more effective tools for practitioners, there is an urgent need for robust and well-validated methodologies which address the problem in its entirety, thus completing the chain and provided a true predictive capability [S3]. This would open the door to a host of new applications, including fire forensics to assist in determining causes of fatalities, supplementing expensive full-scale fires tests, and ultimately in building design, and could transform the application and exploitation of FSE methodologies. It is essential that any such methodology can be effectively exploited by the fire community, so it must be undemanding computationally (so that it can be run on computers typically used by consultants) and must effectively accommodate the specific requirements of real-world fires, i.e. large-scale building scenarios involving a very broad range of lengthscales, and multiple and often complex fuel sources, where significant contributions to toxic products yields may arise both from complex formation processes in the gas phase and directly from the solid-phase, via pyrolysis of combustible boundary materials [S2]. Here an advanced methodology is proposed in which each of these processes can be effectively accommodated, based on the solution of transport equations for each chemical species of interest. The focus of this proposal is on CO prediction, but the method could in future be extended to include other toxic species. The key research question to be addressed is how to most effectively achieve chemical source term closure which is the essential modelling challenge in turbulent combustion systems. Different approaches will be investigated, including a fundamental method based on directly solving the coupled species balance equations using simplified quasi-laminar expressions, and a more sophisticated method which is an extension of the flamelet modelling approach. These predictions will be benchmarked against existing approaches which rely on conventional flamelet representations of toxic product yields and extensions to the simple eddy breakup concept approach, as described in the literature [S4]. The new methods will be validated against relevant experimental data from realistic fire scenarios designed to fully test the generality of the new modelling strategies [S2, S3, S5]. Detailed recommendations will be prepared on exploitation of the methodology, considering the fundamentally competing demands of computational resources and accuracy.References========S1. Babrauskas, V., Levin, B. C., Gann, R. G., Paabo, M., Harris, Jr, R. H., Peacock, R. D. & Yusa, S. (1991) Toxic potency measurement for fire hazard analysis , Special Pub. 827, NIST, Dec 1991S2. Pitts, W.M. (1995) The Global Equivalence Ratio concept and the formation mechanisms of carbon monoxide in enclosure fires , Prog. Energy Combust. Sci., vol. 21, pp. 197-237S3. Purser, D. & Purser, J. (2003) The potential for including fire chemistry and toxicity in fire safety engineering , BRE Client report 202804, 26 Mar 2003S4. Hyde, S.M. & Moss, J.B. (2003) Modeling CO production in vitiated compartment fires , Proc. 7th Int. Symp. Fire Safety Science, pp. 395-406 S5. Smith, D.A., Marshall, N., Shaw, K., & Colwell, S. (2001) Correlating large-scale fire performance with the Single Burning Item test , Proc. 9th Int. Interflam Conf., pp. 531-542