几类建筑材料的燃烧热值的探讨

建筑材料的燃烧热值是表征建筑材料潜在火灾危险性的重要参数,是计算建材燃烧释放热量和火灾荷载必不可少的基础数据。文章用氧弹量热仪通过"香烟法"对几种常用建筑材料的燃烧热值进行测试,并对其试验数据进行对比分析,试验结果表明不同建筑材料的燃烧热值差别很大,即使同种建筑材料之间也会因为其成分的差异存在比较大的差异文章旨在为建筑材料在建筑设计防火规范中的应用提供参考。     

苯甲酸作助燃剂氧弹法测定浓黑液的发热量

为了使浓黑液作为工业炉燃料得到充分利用,采用苯甲酸作助燃剂,氧弹法直接测定浓黑液的发热量,取得满意的结果     

Relationship between heat of combustion,lignin content and burning weight loss

The measurements of effective heat of combustion obtained from the Cone Calorimeter test for several wood composites (different types of plywood and particle board) at horizontal configuration are presented. Comparison of the average effective heat of combustion at different irradiation shows no correlation to gross heat of combustion measured in the oxygen bomb calorimeter. It was also found, that for the materials studied, there is no statistically significant correlation of heat of combustion to lignin content, but on the other hand, there is an evidence of correlation to the burning weight loss of the samples, but further investigation is necessary. Additionally, the effective heat of combustion is shown as a function of time for different external radiant heat-flux level for the chosen materials. Similar profiles have been found for remaining samples. Two different types of such curves can be distinguished. © 1998 John Wiley & Sons, Ltd.     

Characteristics of the combustibility of fibre-forming polymers,fibres, and fibre materials (textiles)

The features of ignition, combustion, and the basic combustibility indexes of fibre-forming polymers, fibres, and fibre materials (textiles) are briefly analyzed. Data are reported on the basic combustibility indexes and their dependence on the type and chemical structure of the polymer. Ways of reducing the combustibility of fibres and fibre materials are briefly characterized. Data are reported on the basic types of difficultly combustible fibres and textiles. Special attention is focused on the products of pyrolysis and combustion with respect to their toxicity.     

Investigation of a combustible material in the fire of Hengyang merchant's building

Agaric, a kind of important combustible material in the fire of Hengyang merchant's building, was investigated using different experiment equipments. Its degradation and pyrolysis behavior were studied by means of thermogravimetric and kinetic analysis and pyrolysis gas chromatography–mass spectroscopy analysis. External radiation heat and internal heat were used to ignite the agaric. For external radiation ignition, a series of bench‐scale fire tests were done in cone calorimeter in accordance with ISO 5660. As for the internal heat ignition, a fire test was carried out in a full‐scale room in accordance with ISO 9705. Multi‐parameter measurement, including heat release rate (HRR), mass loss rate (MLR), temperature field and species concentration, has been accomplished. Meanwhile, the process of a full‐scale fire test was numerically simulated. The computational results were consistent with experiment data, which will lay down a good foundation for further study in fire reconstruction of the whole fire. Copyright © 2008 John Wiley & Sons, Ltd.     

Surface temperature measurements on burning materials using an infrared pyrometer: accounting for emissivity and reflection of external radiation

This paper demonstrates the successful use of an infrared pyrometer, operating in the 8–10 µm wavelength band, to measure the surface temperature of combustible specimens in a heat release calorimeter. The temperature histories of ten different materials were measured in the ICAL (intermediate scale calorimeter). The set of materials comprised four wood products, gypsum board, polyisocyanurate foam, PVC floor tile, PMMA and two non‐combustible boards. A small‐diameter bare thermocouple was installed on each specimen in order to determine an accurate temperature for comparison. The spectral emissivity and the spectral flux reflected from the surface were measured simultaneously and used to correct the apparent temperature measured by the pyrometer. The spectral emissivity and reflected spectral flux were both constant prior to ignition for all the combustible materials. During the burning phase all the combustible materials had a spectral emissivity very close to unity. The agreement between the temperatures measured with the pyrometer and thermocouple was not affected by the flame. The wood products, the polyisocyanurate foam and the calcium silicate board required no correction for reflected spectral flux over the whole temperature range. Copyright © 2004 John Wiley & Sons, Ltd.     

Combustibility of building materials

Until the 1960s ASTM E136 and CAN/ULC-S114 test methods were adequate for determination of non-combustibility in materials being used to construct most buildings. However, since then there has been a very large increase in the use of products that are considered safe for construction of buildings required to be noncombustible but which are classified as combustible by these simple pass/fail tests. Therefore, Forintek Canada Corp. have developed an approach to define the combustibility of these new materials, based upon their release of heat when tested using the ASTM E1354 cone calorimeter.     

用氧弹量热计测定碳酸钙的分解焓

探讨了利用氧弹量热计测定固体物质分解焓的方法,准确称取一定量的固体样品和基准物质,均匀混合后压片,放入氧弹量热计燃烧,记录燃烧前后时间和氧弹量热计温度变化数据。采用雷诺温度校正曲线法,求出样品燃烧前后系统温度的变化值,用盖斯定律计算出固体物质的分解焓。通过测定碳酸钙的分解焓,结果的相对误差为2.74%,在允许的误差范围内,且方法简单,重现性好,准确度高,说明用此方法测定固体物质的分解焓是可行和可靠的。     

Update for combustion properties of wood components

The combustion properties of various biomass and wood materials from various references and from our laboratory were reanalysed. The net heat of combustion for cellulosic materials was found to be 13.23 kJ/g times the ratio of stoichiometric oxygen mass to fuel mass, r_o, regardless of the material composition. Bomb calorimeter data for original, charred and volatilized material components provide gross heating values, while elemental analysis of the materials for carbon, hydrogen, oxygen and ash provide direct evaluation for r_o. We corrected these data as provided in various references by converting gross heating values to lower heating values and converting elemental compositions, char fractions and r_o to a moisture‐free and ash‐free basis. Some existing formulae were found to disagree with data from vegetation, charred wood with high ash content, and with volatiles from cellulose treated with the fire retardant NaOH. We also established various functional correlations of r_o with elemental compositions, or volatization fractions of untreated and treated materials, or material fractions for cellulose, lignin and extractives, or volatile fractions for tar, combustible gases and inert gases in pure nitrogen carrier gas. An interesting predictive result provides nearly constant heat of combustion while the volatile tar fraction is decreasing and combustible and inert gas fractions are increasing with time during the charring of Douglas‐fir wood. Published in 2002 John Wiley & Sons, Ltd.     

Fire-hazard assessment of extended-chain polyethylene and aramid composites by cone calorimetry

A cone calorimeter is used to determine the fire performance of polymer composite materials containing combustible reinforcing fibres in addition to combustible matrix resins. Extended-chain polyethylene and aramid fibre-reinforced composites containing epoxy, vinylester and phenolic matrix resins are examined at various cone irradiances. Values for time to ignition, rate of heat release, effective heat of combustion, smoke density and evolved carbon monoxide and carbon dioxide are reported for the reinforcements, matrix resins and composites. The reinforcements have a significant effect on the fire-hazard properties of the composite materials. For the epoxy and vinylester composites, times to ignition reflect those of the component of higher ignitability. This was not the case for the aramid-reinforced phenolic composite, in which the resin surface layer hinders combustion of the fabric reinforcement. Resin and reinforcement contributions to the composite rate of heat release behaviour as a function of time are generally discernible.     

氧弹卡计测定食用大豆油热值

为了能够直接测定食用大豆油的燃烧热,采用药用胶囊装取大豆油试样进行测定。利用SHR-15型精密量热计系统地测量了大豆油的燃烧热。采用SWC-ⅡD精密数字温差仪记录时间与温度变化数据,运用Origin6.0数据处理软件并结合雷诺温度校正法得到?T,计算出氧弹卡计的热容和食用大豆油的燃烧热值,此法准确、简便、实用,可用于日常检测工作。     

Heats of combustion of high temperature polymers

The heats of combustion for 49 commercial and developmental polymers of known chemical structure were determined using an oxygen bomb calorimeter according to standard methods. The experimental results were compared with thermochemical calculations of the net heat of combustion from oxygen consumption and the gross heat of combustion from group additivity of the heats of formation of products and reactants. The polymers examined were thermally stable, char forming thermoplastics and thermoset resins containing a significant degree of aromaticity and heteroatoms including — nitrogen, sulphur, phosphorus, silicon, and oxygen in linear and heterocyclic structures. The gross and net heats of combustion calculated from polymer enthalpies of formation and oxygen consumption thermochemistry were within 5% of the experimental values from oxygen bomb calorimetry. The heat released by combustion per gram of diatomic oxygen consumed in the present study was E=13.10±0.78 kJ/gO₂ for polymers tested (n=48). This value is indistinguishable from the universal value E13.1 kJ/gO₂ used in oxygen consumption combustion calorimetry. Published in 2000 by John Wiley & Sons Ltd.     

Combustibility of cyanate ester resins

Flaming and non‐flaming combustion studies were conducted on a series of polycyanurates to examine the effect of chemical composition and physical properties on the fire behavior of these crosslinked, char forming, thermoset polymers. Heats of complete combustion of the polymer and fuel gases were determined by oxygen bomb calorimetry and pyrolysis‐combustion flow calorimetry, respectively. Fire calorimetry experiments were conducted to measure the total heat released, the rate of heat release and the smoke generation in flaming combustion. Fire response parameters derived from the data include the thermal inertia, heat of gasification, effective heat of combustion and combustion efficiency. Halogen‐containing polycyanurates exhibited extremely low heat release rate in flaming combustion compared with the hydrocarbon resins yet produced significantly less smoke and comparable levels of carbon monoxide and soot. Published in 2005 by John Wiley & Sons, Ltd.     

Thermal degradation of epoxy resin/carbon fiber composites: Influence of carbon fiber fraction on the fire reaction properties and on the gaseous species release

The thermal degradation of epoxy resin/carbon fiber composites has been performed in ISO 5660 standard cone calorimeter using a piloted ignition. Two kinds of composites that differ by their volume fractions in carbon fiber (56 and 59 vol.%) were tested in this study. The cone calorimeter irradiance level was increased up to 75 kW m^?2 to characterize the carbon fiber volume fraction influence on the composite thermal degradation. Thus, main flammability and combustibility parameters were determined and calculated such as mass loss, mass loss rate, ignition time, thermal response parameter, ignition temperature, thermal inertia, and heat of gasification. As a result, all the characteristic parameters for the thermal resistance of composites were decreased when the carbon fiber volume fraction increased. Moreover, the main gaseous products (such as NO, CO, CO₂, HCN, H₂O, and lightweight hydrocarbons) emitted as well as the oxygen consumption during the composite thermal decomposition were also quantified simultaneously with a portable gas analyzer and a Fourier transform infrared spectrometer. The main species emission yields calculated from the gas analysis results increased slightly when the carbon fiber volume fraction was increased in the initial sample. The epoxy composite was represented as a sooty material with a significant production of soot particles during the combustion process. Furthermore, heat release rate, total heat release, and effective heat of combustion were calculated by using the oxygen consumption calorimetry technique. The results obtained showed that a small increasing of composite carbon fiber amount induced a sharp decrease of heat release rate and total heat release. Copyright © 2014 John Wiley & Sons, Ltd.     

近化学专业燃烧热实验测定的绿色化改进

在燃烧热测定实验中,萘一直是作为被测的燃烧物。然而萘在室温下易挥发升华,污染大气且有致癌性。以蔗糖作为被测物质而代替萘,对其燃烧热测定实验进行改进,能从根本上解决传统实验方法中存在的污染环境问题,从而实现实验教学过程中的绿色无污染化,还培养了学生的环境保护意识,提高学生实验素质,改进了实验效果。通过实验测定,算出用氧弹式量热计来测定蔗糖固体的等压燃烧热(-5 743.9 k J?mol~(-1))与文献值(-5 643 k J?mol~(-1))的误差为-1.39%(小于3%),实验结果较为准确。     

Combustion heat of the Al/B powder and its application in metallized explosives in underwater explosions

An underwater explosion test is used to determine the detonation properties of metallized explosives containing aluminum and boron powders. An oxygen bomb calorimeter (PARR 6200 calorimeter, Parr Instrument Company, USA) is used to obtain the heat of combustion of the metal mixtures. As the content of boron powders is increased, the heat of combustion of the metal mixtures increases, and the combustion efficiency of boron decreases. The highest value of the combustion heat is 38.2181 MJ/kg, with the boron content of 40%. All metallized explosive compositions (RDX/Al/B/AP) have higher detonation energy (including higher shock wave energy and bubble energy) in water than the TNT charge. The highest total useful energy is 6.821 MJ/kg, with the boron content of 10%. It is 3.4% higher than the total energy of the RDX/Al/AP composition, and it is 2.1 times higher than the TNT equivalent.     

A study of fire performance of textile membranes used as building components

The advantages of textile materials as building components include low weight, and in the case of textile membranes, the advantages include translucency and architectural possibilities. A common disadvantage, however, is the fire property of textile materials, which highlights the importance of fire safety assessments for building application of such materials. The work presented in this paper was conducted within the European project contex‐T, ‘Textile Architecture – Textile Structures and Buildings of the Future’. This paper presents the results of reaction‐to‐fire tests required for European Standard (EN) 13501–1 classification conducted with a number of textile membranes. The classification results are compared for a selection of these membranes with the information gained from a large‐scale reference test that was designed within the project. The reference test was based on the International Organization for Standardization (ISO) 9705 room test. It was seen that the reference test could separate the performance of the different types of membranes investigated and the repeatability of duplicate tests performed was acceptable. However, the classification of the materials by test results from the Single Burning Item (SBI) test (EN 13823) and the small flame test (EN ISO 11925–2) did not reflect the performance of the membranes in the large‐scale test properly in all aspects important for fire safety. Most significantly, the ‘burn‐through’ and the associated opening of a hole in the polyvinyl chloride/polyester membranes tested ventilated the hot smoke gases out of the reference room that resulted in limited flame spread and heat production. This mechanism is not modelled correctly by the SBI test, which leads to a discrepancy between classification and large‐scale behaviour. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of retainer frame,irradiance level and specimen thickness on cone calorimeter test results

The effects of retainer frame use, irradiance level and specimen thickness were studied as the second phase work of a round robin project on the cone calorimeter. The project was conducted in support of various U.S. building code groups, developing a system to determine the degrees of combustibility of building materials. The results of the second phase and a comparison with the corresponding round robin results conducted at 75 kW/m² according to the Board for the Coordination of the Model Codes (BCMC) protocol, are presented here. For most of the materials, no significant differences in parameters measured in the cone calorimeter were found when the retainer frame was not used, versus when the retainer frame was used. The irradiance of 50 kW/m² compared with 75 kW/m² produced significantly longer ignition times (with one exception) and lower heat‐release‐related variables as expected. The exception was gypsum board, for which heat release related values were usually higher at 50 kW/m² than at 75 kW/m². The specimen thickness effect could not be studied adequately due to the small number of tests conducted. A significant thickness effect was shown for the heat‐release‐related variables but not for time to ignition. The effect, however, was opposite for polyurethane foam in comparison with cellulosic materials. Copyright © 2004 John Wiley & Sons, Ltd.     

Rates of heat and smoke release of wood in an ohio state university calorimeter

Particleboard, Douglas fir plywood and red oak were tested for heat and smoke release rates under different heat flux levels, piloted and unpiloted conditions, and vertical and horizontal orientations in an Ohio State University calorimeter. The chamber was instrumented to obtain heat release data by both the standard thermal and oxygen consumption methods simultaneously. Heat and smoke release data obtained by both methods are reported. The heat release rates by the thermal method are consistently lower than those by the oxygen consumption method. Variability in results is consistently lower using the oxygen consumption method. The heats of combustion calculated by oxygen consumption are close to those calculated from measurements with the oxygen bomb. The heat release rates measured on particleboard using the standard thermal method are in agreement with measurements on the same material in other Ohio State University calorimeters.     

The rapid mass calorimeter: A route to high throughput fire testing

The rapid mass calorimeter based on reduced‐size specimens is proposed for accelerated fire testing and put up for discussion, particularly for flame retarded polymeric materials. A mass loss calorimeter is combined with a semiautomatic sample changer. Experiments on specimens of reduced size were conducted on poly(methyl methacrylate), poly(propylene), polyamide 66, poly(ether ether ketone), and pine sapwood square samples with edge lengths of 100, 75, 50, 25, 20, and 10 mm. Specimens of 20 × 20 mm² were selected to achieve a crucial reduction in specimen size and a measuring protocol developed. A total of 71 different polymeric materials were investigated in the rapid mass calorimeter and cone calorimeter for comparison and several materials with different heat release rate characteristics in the pyrolysis combustion flow calorimeter to test this additional screening method as well. The important fire properties obtained in the rapid mass calorimeter show reasonable correlation with the cone calorimeter results but also with the oxygen index. All in all, the rapid mass calorimeter produces reliable and meaningful results and, despite acceleration and size reduction, still allows for a certain degree of burning behavior interpretation. Material savings of 96% and time savings of around 60%‐70% are achieved compared to measure cone calorimeter.