| Since entering 21th century, energy has become a constraint to maintain steady and rapid growth of China's economic and social sustainable development. Building energy consumption is a major aspect of energy consumption in China. According to statistics, China's building energy consumption accounted for 10% of the total energy consumption in 1978 to the current 40%. Vigorously develop energy-efficient buildings has become the society and people's consensus. Some excellent energy saving insulation materials have been widely used in high-rise building facade construction, such as moulded polystyrene foam (EPS), extruded polystyrene foam (XPS), etc. However, these materials catch fire, easy to produce flammable and melt drops, which is easy to ignite the other materials.At the same time,there are no detailed fire protection requirements in the current design standards.So if this kind of materials is in a fire, the fire hazard is relatively large. Therefore, studying the ignition and flame spread characteristics of the typical insulation material PS will not only reveal the peculiar phenomena and mechanisms of thermoplastic insulation materials during flame spread process,but also can provide the guidence for the fire protection design of the high-rise building facades in insulation system.Flame spread of the Insulation material is a complex physical and chemical process, which is not only influenced by the insulation material's physical and chemical properties,but also the sample size, the external radiation, atmospheric pressure and oxygen concentration have a great influence on it. This paper uses the theoretical and experimental methods to study the flame spread of insulation materials.By setting up a Small-scale experimental system,the flame spread characteristics of insulation materials including the inner solid structure(solid phase temperature distribution,preheating and pyrolysis zones,etc.),flame gas structure(flame shape,flame temperature distribution etc.),flame spread speed and weight loss rate and other parameters in the multi-parameter coupling environment (sample size, inclining angle, atmospheric pressure, oxygen concentration, etc.) are revealed.In this paper, small-scale flame spread experiments of EPS and XPS of the same size are conducted in a plateau area in Lhasa and a plain area in Hefei. And the flame spread speed,average length of the pool fire, average flame height are analyzed.So,the flame spread characteristics and fire hazard are revealed in different environments.The effect of different parameters and environments to the flame spread characteristics of the insulation material PS is experimentally studied. These parameters include the material thickness, width, placing angle and other factors. The change law of the length of pool fire,flame height and the lateral flame area with the thickness of PS is get in plateau and plain environments.And the same time,for the different thicknesses of EPS and XPS inclined at different angles(-30°~ 30°),the flame spread characteristics with the enviroment is studied. It is found that for EPS in Lhasa or Hefei environment, the flame spread speed increases with the inclined angle; while for XPS, when the inclined angle is negative, in Lhasa, the flame spread speed increases with the decreasing of inclined angle.Also, when the inclined angle is relatively large , XPS both in Lhasa and Hefei have appeared the secondary ignition phenomenon,while EPS not. At the same time,the effect of sampe width to the flame spread characteristics of EPS and XPS in plateau and plain environment is revealed. It is demonstrated that for the insulation material PS, when the width is about 10cm ,the flame spread speed reaches minimum value. And when the width is relatively large,for EPS in Hefei, and XPS in Lhasa and Hefei, the flame height in the pool fire zone shows a gradual higher than that in the surface flame zone.The flame spread speed model of insulation material PS is described using the measurements by the infrared cameras and fine thermocouples combined with theoretical analysis,which can well reflect the difference between the thermoplastic and thermosetting materials in flame spread speed aspect.Meanwhile, the flame structure of thermal insulation material PS is analyzed.It is showed that the flame zone of PS is comprised of surface flame zone and pool fire zone. And when the material inclined at different angles, the flame angle and flame length in the surface flame zone are different appearly.Meanwhile,the flame structure of PS inclined at different angles is demonstrated, which shows that the flame spread speed is influenced largely by it. |
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