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According to control theories, mine fires can be considered as an unsteady process after the normal ventilation system is disturbed. Applied the principal of physical chemistry and thermal fluid mechanics, the parameters models of the unsteady state system have been given, such as fuel combustion rate, heat of combustion, concentration, temperature, heat losses, heat resistance, work of expansion and heat pressure difference. The results of the calculation agree approximately with the results of the test. By the computer simulation, it is shown that the main factor of producing the throttling effect is the fire rate, second is the heat resistance and the heat pressure difference. The rate of heat flow that passes through the airway wall is the maximum on the surface, and decrease with time. The heat transfer progresses only within the range of 0..5 m away from theairway wall during combus-tion for 2 hours. It‘s variable for the mass flux rate and the percentage concentration of the gas along the airway of the downstream. When the delayed time is very small, the varidtion can be neglected. Viscosity resistance is the main part of the heat resistance, second is the expansion resistance that is less than tens Pascal when Mach number is very small. Work of expansion is principally tumed into heat losses, only a very small part is consumed by the work of the heat resistance and the inertia acceleration. 相似文献
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聚丙烯酰胺/氧化石墨纳米复合材料的研究 总被引:4,自引:0,他引:4
氧化石墨具有良好的层状结构,其层间具有丰富的官能团,能与有机聚合物形成插层纳米复合材料进而改善材料的性能.采用层离吸收-原位聚合法制备了聚丙烯酰胺/氧化石墨纳米复合材料,并采用XRD、HREM及DSC等对其结构和性能进行了表征。结果表明,聚丙烯酰胺与氧化石墨两者之间存在着较强的相互作用,材料的玻璃化转变温度得到提高,层离吸收-原位聚合法是获得聚丙烯酰胺/氧化石墨层纳米复合材料的有效途径,聚丙烯酰胺在氧化石墨中存在着多种排列方式,不同层间距(1.6nm和2.8nm)的聚丙烯酰胺/氧化石墨纳米复合结构同时存在。 相似文献
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认识火灾机理和规律是防治火灾的关键 总被引:2,自引:0,他引:2
范维澄 《新安全 东方消防》2003,(5)
每一起火灾,都经历孕育、发生和发展这样一个过程。对这样一个复杂过程机理的认识究竟会对火灾的防治有什么样的现实意义,许多人感到迷惑。这里范维澄说了一件发生在1987年5月大兴安岭特大火灾期间的一件事。当时他只是一名研究燃烧学的专家,刚刚涉猎火灾科学。有一天,他看到电视上播发了一则消息:为了阻止火灾蔓延,指挥部命令数万名增援的解放军官兵开辟了一条30米宽的隔火道。对着电视屏幕,范维澄心急如焚。凭着对燃烧学多年的研究,他感到,这条隔火道根本不能阻断熊熊的森林大火。果然,第二天的媒体报道印证了他的判断。 相似文献
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1 INTRODUCTIONOrganic intercalatedlayeredsolidshavebeenstudiedbyscientistsindifferentfieldsformanyyearsbecauseoftheirnew physicalandchemicalpropertiessuchaselectricalproperties[1] ,mechanicalproper ties ,thermalbehavior[2 ] ,surfaceandinterfacialproperties[3] .Graphiteoxide (GO)hasbeenstudiedformany years ,itsstructuralmodel[4 6 ] ,formationprocessandkinetics[7,8] havebeenstudiedindetail.IthasbeenreportedthatGOpossessesC OHande poxidefunctionalgroups[9] whichmakegraphiteox ideeasilyabs… 相似文献
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聚合物/层状粘土纳米复合材料阻燃性能研究进展 总被引:14,自引:1,他引:13
聚合物/层状粘土(PLC)纳米复合材料是近十年来研究的热点。由于PLC纳米复合材料具有常规聚合物复合材料所没有的结构、形态以及较常规材料更加优越的力学性能、耐热性能、气液体的阻隔性能等,所以具有广泛的工业应用前景。文中综述了PLC纳米复合材料的制备、性能、结构及其在阻燃方面应用研究的现状。 相似文献
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研究了对核能系统火灾安全具有重要意义的核动力装置安全壳内氢气的扩散传播过程,采用圆柱坐标下的三维非稳态数学模型研究了含阻挡物的半圆柱体密闭壳体下部氢气在浮力作用下的运动过程。 相似文献