封闭空间火灾中燃料烟尘对墙体所受热通量的影响(英文)

Effect of fuel sootiness on the heat fluxes to the walls in enclosure fires

尽管在封闭空间内已经做过很多关于气体温度和燃烧率的研究,但目前仍然缺乏封闭空间内墙体上热通量及其分布方面的信息。该热通量数据是确定墙体材料特别是玻璃的热反应及性能的必要输入参数。试验用封闭空间墙体上的热通量是通过多块薄钢片(25.4mm×25.4mm×3mm)以及钢片周围隔热材料的温度推算出来的。另外,笔者还测量了热流计附近墙体的质量损失率和温度。试验用封闭空间是ISO标准墙脚火试验的1/3,有六个开口,燃料为甲醇、IMS(工业用甲基化酒精)以及甲苯,装在大小不同的三个方形油盘里,油盘放置在封闭空间的内外拐角处。在选择燃料方面,笔者的依据是燃料燃烧产生的烟尘应越来越浓。试验发现,与以前对地板的研究结果有所不同的是,墙体上的热通量不仅仅取决于烟气温度,还取决于热释放速率的强弱以及燃料所产生的烟尘的多少。另外,对甲醇、IMS以及甲苯所产生的热通量的比较发现,对流热可以与辐射热通量(热烟气流以及封闭墙体造成)以及来自烟羽流的辐射热通量分开。

Even though considerable work has been performed regarding gas temperatures and burning rates in enclosures, scant information is available for the heat fluxes and their distributions on the walls of an enclosure. These heat fluxes are necessary input for determining the thermal response and performance of the wall materials and especially glazing. The heat fluxes on the wall of an experimental enclosure were deduced from the temperatures in several thermally thin small steel plates （25. 4 mm ）〈 25. 4 mm ）〈 3 mm） and in the insulation surrounding the steel plates. In addition, the mass loss rate and gas temperatures near these heat flux gauges were measured. The experimental enclosure was the 1/3 linear scale of the ISO room corner test having six openings and three square-pans of variable size burning Methanol, IMS （Industrial Methylated Spirits） and Toluene at the corner and in the center of the enclosure. By choosing fuels with an increased degree of sootiness it was found that the heat fluxes do not depend only on the gas temperature, as claimed before for heat fluxes on the floor, but also on the magnitude of the heat release rate and the fuel sootiness. Moreover, comparison of the heat fluxes for methanol, IMS and toluene allow the separation of convective from radiative heat fluxes owing to hot gases （and the enclosure walls） and from the radiative heat fluxes from the fire plume.