Prediction of toxic species in fire

大多数火灾死亡与热闪络后火灾中产生的有毒产品的远程运输有关，特别是与一氧化碳（CO）有关[S1，S2]。目前，数值工具在描述这些有毒产品的运输方面是有效的，但无法准确预测火灾中产生的数量-因此来源缺失[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，迫切需要一种强大且经过良好验证的方法，以解决整个问题，从而完成链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，以帮助确定死亡原因，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方法的应用和开发。重要的是，任何这样的方法可以有效地利用消防界，所以它必须是不苛刻的计算（以便它可以在通常由顾问使用的计算机上运行）并且必须有效地适应真实世界火灾的具体要求，即涉及非常宽范围的长度尺度的大规模建筑物场景，以及多个且通常复杂的燃料源，其中，通过可燃边界材料的热解，气相中复杂的形成过程和直接来自固相的过程都可能对有毒产物产率产生重大影响[S2]。在这里，提出了一种先进的方法，其中每一个这些过程可以有效地容纳，基于每个感兴趣的化学物种的传输方程的解决方案。该提案的重点是CO预测，但该方法将来可以扩展到包括其他有毒物质。要解决的关键研究问题是如何最有效地实现化学源项关闭，这是湍流燃烧系统中的基本建模挑战。不同的方法将进行调查，包括一个基本方法的基础上直接求解耦合的物种平衡方程，使用简化的准层流表达式，和一个更复杂的方法，这是一个扩展的小火焰建模方法。这些预测将以现有方法为基准，这些方法依赖于有毒产品产量的传统小火焰表示和简单涡流破碎概念方法的扩展，如文献[S4]所述。新方法将根据来自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根本竞争需求，将编写关于利用该方法的详细建议。Babrauskas，V.，Levin，B. C.的方法，江恩河G.，Paabo，M.，小哈里斯河H、皮科克河D. & Yusa，S.（1991）火灾危险分析的毒性效力测量，特别出版物。827，NIST，1991年12月S2。Pitts，W. M.（1995）全球当量比概念和一氧化碳在封闭火灾中的形成机制，Prog。能量燃烧科学，第21卷，第197-237S3. Purser，D. & Purser，J.（2003）在消防安全工程中包括火灾化学和毒性的潜力，BRE客户报告202804，2003年3月26日S4。Hyde，S.M. & Moss，J.B.（2003）在受损的隔间火灾中模拟CO产生，Proc.7th Int. Symp.消防安全科学，pp。395-406 S5。史密斯检察官N.马歇尔，Shaw，K.，&科尔韦尔，S.（2001）将大规模火灾性能与单一燃烧物品测试相关联，第9届国际火焰会议，pp. 531-542

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