具有核-壳结构的钾盐溶液@气相二氧化硅粉体介质的灭火效能及其灭火机理研究

As a fire extinguishing agent, the potassium aqueous solution(PAS) has some shortcomings of corrosivity, poor spreadablity and the optimal extinguishing efficiency is necessary to rely on specific sprinkler and pressure. Aiming at these problems, the project proposes to prepare a new kind of core-shell structure extinguishing powders(CSSEP) with environment-friendly and high efficiency. The composites comprise of a shell outside with fumed silica, in which is the core as fire suppressant of PAS. After proper physical modification, a solid-liquid two-phase fire extinguishing powder with a maximum liquid content of up to 90% is formed by high speed shear method. The preparation methods, physicochemical properties and thermal properties of the CSSEP are planned to be studied. A comprehensive evaluation system which integrates multi-scale fire extinguishing experiment and multiple fire models will be established to test the efficiency of the CSSEP. Further study is made on the intrinsic relationship between the extinguishing efficiency of the CSSEP, the kinds of potassium compounds and the mass fraction of the solution. A series of advanced optical diagnostic methods including schlieren system, high-speed CCD camera and grating spectrometer will be used to investigate the fire suppression process. The fire extinguishing results of the CSSEP will be compared with that of pure fumed silica and the droplet of PAS so as to study the synergistic fire extinguishing effect and obtain a comprehensive fire extinguishing dynamics mechanism of the CSSEP. The research conclusions are believed to provide theoretical and technical guidance for the design, development and application of a new type of fire extinguishing medium. Meanwhile, the conclusions will provide information support for improving the research method of fire extinguishing mechanism and the kinetic mechanism model of chemical active substances.

针对传统水系灭火剂和干粉灭火剂的不足，本项目旨在设计一种环境友好且高效的新型核-壳结构粉体灭火介质。该介质以具有化学惰性的气相二氧化硅为外壳，以具有较高灭火效能的钾盐溶液为内核，经过适当的物理改性，通过高速剪切法，形成含液量最高可达90%的固-液两相粉体灭火介质。研究核-壳结构粉体的制备方法、理化性能和热性能；构建集多尺度灭火实验与多种类火灾模型于一体的核-壳结构粉体灭火效能综合评价体系，进一步研究该粉体的灭火效能与含钾化合物种类和溶液质量分数之间的内在联系；通过纹影系统、高速CCD相机和光栅光谱仪等先进的光学诊断方法联用技术，深入研究新型粉体抑制熄灭扩散火焰的过程，并与干粉单体和雾滴单体的灭火过程相比较，揭示新型粉体的协同灭火效应以及灭火动力学机理。研究结论可为新型灭火介质的研发及推广提供重要的理论依据和技术指导,为完善灭火机理的研究方法和化学活性物质的动力学机理模型提供信息支持。

本项目针对钾盐溶液作为灭火介质在实际应用中的不足，旨在设计一种环境友好并且清洁高效的核-壳结构新型复合粉体灭火介质。该灭火介质以具有化学惰性和耐热性的纳米二氧化硅为外壳，以具有较高灭火效能的钾盐溶液为内核，经过适当的物理改性，通过高速剪切法，形成含液量高达90%以上的钾盐溶液@纳米SiO2粉体灭火介质。研究了该灭火介质的制备方法、理化性能和热性能；构建集多尺度灭火试验与多种类火灾模型于一体的灭火效能综合评价体系，进一步研究了该介质的灭火效能与溶质种类及质量分数之间的内在联系，并与典型商用灭火介质的灭火过程相比较，揭示该灭火介质的协同灭火效应以及灭火机理。.研究发现：（1）基于全淹没灭火机理的小尺度环己烷火试验中，该介质的灭火效能与超细干粉灭火剂相当，灭火用量比细水雾减少44.3%；（2）基于局部保护灭火机理的汽油火试验中，该介质的灭火效能明显优于细水雾，在小尺度和中尺度试验环境下分别提升13.4%和27.7%，说明该介质的优势在更大的施放压力和火源功率场景下尤为明显；（3）在相同的试验条件下，该介质抑制柴油火的效能比汽油火高12.7%，说明其更适宜抑制燃烧过程中油温较高的火灾；（4）应用数值计算的方法从热力学和动力学的角度论述了钾盐具有化学灭火效能的灭火活性关键组分为气态KOH，其对燃烧过程的影响主要是通过控制燃烧过程中含OH基的关键基元反应，捕获火焰中的OH自由基达到抑制效果。钾盐溶液@SiO2干水的灭火机理是通过冷却、稀释、均相自由基催化抑制和异相自由基湮灭等综合协同作用的结果。研究结论可为新型灭火介质的设计研发及推广应用提供重要的理论依据和技术指导，为完善灭火机理的研究方法和化学活性物质的动力学机理模型提供信息支持。