少量聚氨酯泡沫样品从阴燃到有焰燃烧的变化研究

试验主要观察处于阴燃状态的少量聚氨酯泡沫样品的流速、氧气浓度和辐射热通量对气／固界面的影响。因为此试验研究对象是少量聚氨酯汽沫，所以阴燃蔓延以厦转化到有焰燃烧时必须借助于降低热损失并同时增加其氧气浓度。试验中，我们把呈平行六面体的样品竖向放置在风道中。样品的其中三个侧边处在高温状态，第四边暴露在上升气流和辐射中。结果发现，随着气流流速的降低以度氧气浓度的增加，或者增加辐射通量，都会加快其变成有焰燃烧的过程，减少这种变化的延误时间。试验结果表明，炭化部位内部的有焰变化因阴燃作用而出现滞后，这已经通过超声波穿透样品内部得到了证实。笔者这里给出了简化了的分析，证明这种变化可以作为一个气相燃烧程序进行处理。     

浅谈阴燃火灾

众所周知,通常材料着火后大都出现火焰(即火苗)。而火焰又是气相燃烧现象。对于多孔材料、粉状材料,当通风不良或燃烧强度较低时,着火后分解产物来不及燃烧就以烟的形式跑掉了,因而不能形成火焰,仅发生分解,炭化和灼热燃烧。这就是阴燃。     

地下商业建筑消防设计初探

<正>一、地下商业建筑的火灾特点1、不完全燃烧产物和有毒气体含量多,火场内部温度高,阴燃火势隐蔽,易引起复燃。地下建筑因其密封性好,火灾后大量物质的燃烧速度与燃烧的充分性受到影响,造成燃烧速度慢、阴燃时间长、产生浓烟和大量有毒气体,同时蓄热温度随之升高,产生高热烟气流。而当某一阴燃部位突然同外部空气形成对     

逆向阴燃传播过程和模型

为了解逆向阴燃传播的过程和特点,用聚氨酯泡沫材料在绝热封闭的装置中进行了实验.实验过程用热电偶进行温度的测量,通过调节气体流量观测风速对逆向阴燃的影响.聚氨酯泡沫材料的逆向阴燃可分为两个阶段,第一阶段泡沫材料阴燃变成多孔炭,材料的透过率很小,能进入材料内部参与反应的氧气量也少,气流增大,在增加氧气的同时也带走更多的热量,阴燃传播速度随风速先增大后减小.第二阶段多孔炭的燃烧,空气很容易进入到材料内部,传播速度随风速线性增大,燃烧达到的最高温度值也随风速增大.在第一阶段中逆向阴燃的传播是匀速的,以此建立了一维传播模型,模型模拟结果同实验的结果具有很好的一致性.     

一种无机复合聚苯板的制备与燃烧性能研究

采用具有负热值特性的半水硫酸钙等无机材料为主要添加剂制备阻燃浆液,以低密度膨胀聚苯乙烯泡沫为基体,使用负压顺孔与负压吸附技术,制备了无机复合聚苯板;使用导热系数测试仪测试了该复合材料的保温性能,使用氧指数测试仪、热值测试仪、锥形量热仪、单体燃烧装置测试其燃烧性能。经检测,该无机复合聚苯板的导热系数为0.041 W/(m².K),热值仅为2.91 MJ/kg,氧指数达到39.7%;锥形量热仪测试结果显示,该复合聚苯板在燃烧过程中未发生收缩熔融,且保持一定的形状,其热释放速率峰值、总热释放量、产烟速率峰值以及总产烟量相比聚苯乙烯泡沫基材大幅降低;单体燃烧测试结果显示,该无机复合聚苯板的燃烧性能等级达到A2级,产烟特性等级达到S1级;分析其阻燃机理,认为主要源于二水硫酸钙吸热的分解反应和惰性的分解产物。     

难燃性聚乙烯泡沫塑料板材

难燃性聚乙烯泡沫塑料板材是采用科学配方和合理的工艺技术制成，无毒、无味、不吸水，导热系数低，保温效果好，而且光洁美观，施工方便，使用寿命长，达到了国家标准难燃材料Ｂ１级的要求和消防产品防火性能的要求，可广泛应用于制冷工业、建筑业暖通设施。主要技术参数：氧指数≥３２垂直燃烧平均燃烧时间≤３０ｓ垂直燃烧高度≤２５０ｍｍ烟密度≤７５ＳＰＲ表观密度≥０．０３ｇ／ｃｍ３吸水性≤０．０５ｋｇ／ｍ２压缩强度≥３０ｋＰａ导热系数≤０．０４８Ｗ／（ｍ·Ｋ）联系电话：０５７４－７５９１２８４难燃性聚乙烯泡沫塑料板材…     

碱式硫酸镁晶须复合聚苯板性能研究

采用水热合成法,以低品位菱镁矿为原料制备了碱式硫酸镁晶须,将所得晶须浆料通过真空吸附的方法填充到模塑聚苯板中,得到碱式硫酸镁晶须复合聚苯板,随后研究了碱式硫酸镁晶须对复合聚苯板燃烧热值、抗拉强度、导热系数、产烟密度和产烟毒性的影响。     

热产生率及其测量方法

燃料燃烧时单位时间所产生出的热量是衡量火灾规模和危险程度的首要因素。 我们知道,某种物质的燃烧热是单位重量的该物质在密封容器的纯氧中完全燃烧时所产生的热量。它无疑是说明燃料燃烧特性的一个重要参数,但是燃烧热并不能确切地反映出火灾条件下该燃料燃烧时所实际产生的热量以及它和燃烧时间之间的关系。因为火灾条件下往往没有充足的氧气,经常是不完全燃烧,许多燃料也常会炭化,从有火焰的燃烧转变成无火焰的阴燃;由于燃烧条件的不稳定,燃烧过程中的热产生率也将发生     

影响岩土导热系数测试准确性的因素分析

目前现场测量岩土导热系数方法需要首先确定回填材料导热系数、埋管管壁的导热系数、埋管管间距、钻孔直径、循环水出入口温度以及加热功率等,这些参数测定的准确性影响岩土导热系数测量的准确性。本文分析了上述因素测量准确性对岩土导热系数测试结果的影响规律。研究表明:回填材料导热系数、埋管管间距和加热功率测量的准确性对岩土导热系数测试结果影响较大;而埋管管壁导热系数、钻孔直径和循环水出入口温度测量值的影响较小。     

平板导热系数仪标定方法的探讨

在导热系数检测过程中,平板导热系数仪测量的温度和功率两个参数偏差对导热系数计算结果的影响非常大．因此提高检测仪器对这两个参数测量的准确度和检定仪器测量误差显得非常重要。根据国家标准GB／T10294—2008《绝热材料稳态热阻及有关特性的测定防护热板法》的要求和日常检测下作中反复试验得小的经验,提出一个对平板导热系数仪进行标定和测量误差的可靠方法,以供参考。     

Semi-Empirical Model using Radiant Coal Power to Predict Cigarette Ignition Strength as Measured by Extinction Test

A semi-empirical model was developed to use the radiant coal power of cigarettes in non-contact free smolder to predict the percentage of cigarettes smoldering on 10 layers of filter paper from a sample set that would burn the entire length of the tobacco rod. To develop the model the radiant coal power for cigarettes in non-contact free smolder was measured using infrared imaging and the percentage of the same type of cigarettes smoldering on 10 layers of standard chemical filter paper that burned the entire length of the tobacco rod was measured. From the experimental data, a characteristic coal power and an effective extinguishment threshold were established for the cigarettes. The effective extinguishment threshold was plotted as a function of the characteristic coal power for different cigarette designs, and the optimized Boltzmann model of the data allows the percentage of cigarettes smoldering on 10 layers of filter paper that would burn the entire length of the tobacco rod to be predicted by measuring the radiant coal power for the cigarettes in non-contact free smolder. The model was also used to predict the percentage of cigarettes smoldering on 7 layers of filter paper that would burn the entire length of the tobacco rod. The percentages predicted shows good agreement with the percentages measured for both 7 and 10 layers of filter paper. An erratum to this article is available at .     

Smolder ignition of polyurethane foam: effect of oxygen concentration

Experiments have been conducted to study the ignition of both forward and opposed smolder of a high void fraction, flexible, polyurethane foam in a forced oxidizer flow. Tests are conducted in a small scale, vertically oriented, combustion chamber with supporting instrumentation. An electrically heated Nichrome wire heater placed between two porous ceramic disks, one of which is in complete contact with the foam surface, is used to supply the necessary power to ignite and sustain a smolder reaction. The gaseous oxidizer, metered via mass flow controllers, is forced through the foam and heater. A constant power is applied to the igniter for a given period of time and the resulting smolder is monitored to determine if smolder is sustained without the assistance of the heater, in which case smolder ignition is considered achieved. Reaction zone temperature and smolder propagation velocities are obtained from the temperature histories of thermocouples embedded at predetermined positions in the foam with junctions placed along the fuel centerline. Tests are conducted with oxygen mass fractions ranging from 0.109 to 1.0 at a velocity of 0.1 mm/s during the ignition period, and 0.7 or 3.0 mm/s during the self-sustained propagation period. The results show a well-defined smolder ignition regime primarily determined by two parameters: igniter heat flux, and the time the igniter is powered. These two parameters determine a minimum igniter/foam temperature, and a minimum depth of smolder propagation (char), which are conditions required for ignition to occur. The former is needed to establish a strong smolder reaction, and the latter to reduce heat losses from the incipient smolder reaction to the surrounding environment. The ignition regime is shifted to shorter times for a given igniter heat flux with increasing oxygen mass fraction. A model based on concepts similar to those developed to describe the ignition of solid fuels has been developed that describes well the experimental ignition results.     

阴燃火灾的调查

论述了以香烟作为阴燃火灾最常见的起火源，由阴燃火转化为有焰燃烧的机理，以及阴燃在火灾中形成的痕迹特征。     

干热干冷地区围护结构热工设计对内表面温度及室内热舒适的影响

为了分析干热干冷地区围护结构热工性能对室内热环境的影响,采用物理环境实测结合动态模拟方法对比分析了2组墙体的保温、蓄热性能对内表面温度的影响,并结合太阳辐射季节变化探究了太阳辐射吸收比对室内热舒适的影响.研究表明:实测结果与模拟结果吻合较好,对于干热干冷地区,提高围护结构蓄热性能能够降低夏季内表面温度,对冬季内表面温度...     

棉被阴燃火灾实验研究

针对烟头引燃棉被的火灾案例,实验测量烟头的表面温度及热辐射强度,得到烟头表面最高温度可达289 ℃,很容易引燃棉被等可燃物.通过无被套棉被的阴燃实验和有被套棉被的阴燃转明火实验发现,在没有被套的情况下,棉絮间空隙较大,无法积聚热量,只能阴燃而无明火;有被套情况下,产生的热量大部分被阻隔在棉被内部,散热速度较慢,提供了棉被阴燃转明火所需的热量.     

虚拟热源法研究坝基裂隙岩体渗漏通道

利用虚拟热源法研究坝基裂隙岩体中存在的集中渗漏通道。水库底部通常为低温水,而基岩温度随着深度的增加而升高,坝后温度异常区域可能存在库水渗漏。渗漏水与周围地层将进行热量的交换。低温的渗漏水从地层中吸收热量,而地层则释放出热量,根据能量守恒原理,这两个热量是相等的。将集中渗漏通道看作是一个虚拟线热源,通道以外地层温度的分布仅与渗漏带最外层的温度有关,与渗漏通道内部的温度分布无关,渗漏通道内部的温度是由水流带来的,其外部的温度是靠热传导进行。根据热传导及能量守恒理论,可以推导出温度在地层中的分布趋势,通过温度分布曲线可以确定渗漏范围,建立堤坝渗漏量的虚拟热源法模型;同时,对具体工程实例进行了定量计算。     

Heat loss characteristics for a typical solar domestic hot water storage

It is common practice to predict the performance of solar domestic hot water (SDHW) systems by computer simulation. This process relies on the accurate specification of the system's physical and thermal characteristics, and is often based on a number of simplifying assumptions. An important aspect of system performance is storage heat loss characteristics; however, these are often represented by an average heat loss coefficient or U-value that does not account for the complex geometry of the thermal storage or the interaction of the various inlet and outlet ports that may act as thermal conduits. In addition, most solar storage models assume that the tank temperature profile is one-dimensional and that conduction within the tank wall is negligible. To investigate these effects, tests were conducted on a typical thermal storage used in SDHW applications and included a cool-down test and a heat diffusion test sequence. The values derived from these test sequences were then compared to computer predictions based on estimated thermal properties. In addition, the basic assumptions typically used in the computer modelling of solar storage heat losses (e.g., one-dimensional temperature profiles, minimal tank wall conduction, uniform wall heat loss) were investigated, particularly in the context of a thermally stratified thermal storage.     

Generalized pyrolysis model for combustible solids

This paper presents a generalized pyrolysis model that can be used to simulate the gasification of a variety of combustible solids encountered in fires. The model, Gpyro, can be applied to noncharring polymers, charring solids, intumescent coatings, and smolder in porous media. Temperature, species, and pressure distributions inside a thermally stimulated solid are determined by solving conservation equations for the gaseous and condensed phases. Diffusion of species from the ambient into the solid is calculated with a convective–diffusive solver, providing the capability to calculate the flux and composition of volatiles escaping from the solid. To aid in determining the required material properties, Gpyro is coupled to a genetic algorithm that can be used to estimate the model input parameters from bench-scale fire tests or thermogravimetric (TG) analysis. Model calculations are compared to experimental data for the thermo-oxidative decomposition of a noncharring solid (PMMA), thermal pyrolysis of a charring solid (white pine), gasification and swelling of an intumescent coating, and smolder in polyurethane foam. Agreement between model calculations and experimental data is favorable, especially when one considers the complexity of the problems simulated.     

上宏鞋业清洁能源替代工程介绍

通过对上宏鞋业有限公司用能情况进行深入分析,设计了电加热导热油蓄热供热方案替代原有燃煤锅炉蒸汽供热。以夜间低谷电加热导热油进行蓄热,白天供应生产工艺用热。在节能减排,减少投资,降低运行成本方面取得了较好的成效,该方案可以为当前清洁能源替代工程提供借鉴和参考。