Heat release rate-The single most important variable in fire hazard

fluent中的heat release rate-概述说明以及解释

fluent中的heat release rate-概述说明以及解释1.引言1.1 概述热释放速率在燃烧领域中扮演着至关重要的角色，它是描述燃烧过程中能量释放速率的重要参数。

热释放速率的准确模拟可以帮助我们更好地理解燃烧现象，并优化工程设计。

Fluent是一款流体力学仿真软件，可以用来模拟各种流体现象，包括燃烧过程。

本文将重点探讨在Fluent中如何模拟热释放速率，以及其在燃烧领域中的应用和意义。

通过深入研究和分析，我们可以更好地利用Fluent软件进行燃烧仿真，并为工程实践提供更好的支持和指导。

1.2文章结构1.2 文章结构本文分为引言、正文和结论三部分。

在引言部分，首先对文章的主题进行了概述，介绍了研究的背景和意义。

接着对文章的结构进行了概述，简要说明了各部分的内容和逻辑关系。

最后阐明了本文研究的目的，指明了对Fluent中的heat release rate进行深入探讨的意义。

正文部分主要分为三个小节。

首先介绍了Fluent软件的基本情况，包括其特点、应用领域和优势。

然后重点讨论了燃烧模拟中的heat release rate的重要性，分析了其在燃烧过程中的作用和意义。

最后详细介绍了在Fluent中进行heat release rate模拟的方法和步骤，包括模型选择、边界条件设定和求解器设置等方面。

结论部分对全文进行了总结，强调了对Fluent中heat release rate 研究的重要性和必要性。

同时展望了未来在该领域的研究方向和发展前景。

最后，通过对全文的回顾和思考，对本文的研究成果进行了总结，并提出了对读者的建议和思考。

1.3 目的本文旨在探讨在使用Fluent软件进行热释放速率模拟时的方法和技巧。

通过深入分析Fluent中的热释放速率模拟方法，我们可以更好地了解热释放速率在燃烧模拟中的重要性和应用价值。

同时，本文旨在为研究人员和工程师提供一些有用的指导和建议，以便他们在实际工程项目中更好地应用Fluent软件进行热释放速率模拟。

CONTRIBUTIONS

DOT/FAA/AR-01/31 Office of Aviation Research Washington, D.C. 20591Calculating Polymer Flammability From Molar Group ContributionsSeptember 2001Final ReportThis document is available to the U.S. publicthrough the National Technical InformationService (NTIS), Springfield, Virginia 22161.U.S. Department of TransportationFederal Aviation AdministrationNOTICEThis document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange. The United States Government assumes no liability for the contents or use thereof. The United States Government does not endorse products or manufacturers. Trade or manufacturer's names appear herein solely because they are considered essential to the objective of this report. This document does not constitute FAA certification policy. Consult your local FAA aircraft certification office as to its use.This report is available at the Federal Aviation Administration William J. Hughes Technical Center’s Full-Text Technical Reports page: in Adobe Acrobat portable document form (PDF).Technical Report Documentation Page1. Report No.DOT/FAA/AR-01/312. Government Accession No.3. Recipient's Catalog No.5. Report DateSeptember 20014. Title and Subtitle CALCULATING POLYMER FLAMMABILITY FROM MOLAR GROUPCONTRIBUTIONS6. Performing Organization Code7. Author(s)Richard Walters* and Richard E. Lyon**8. Performing Organization Report No.9. Performing Organization Name and Address *Galaxy Scientific Corporation **Federal Aviation Administration English Creek Avenue, Building C William J. Hughes Technical Center Egg Harbor Township, NJ 08234 Airport and Aircraft Safety10. Work Unit No. (TRAIS)Research and Development Fire Safety Section Atlantic City International Airport New Jersey 0840511. Contract or Grant No.12. Sponsoring Agency Name and Address U.S. Department of Transportation Federal Aviation Administration13. Type of Report and Period CoveredFinal Report Office of Aviation Research Washington, DC 2059114. Sponsoring Agency Code AIR-12015. Supplementary Notes 16. AbstractSpecific heat release rate is the molecular-level fire response of a burning polymer. The Federal Aviation Administration (FAA)obtains the specific heat release rate of milligram samples by analyzing the oxygen consumed by complete combustion of the pyrolysis gases during a linear heating program. Dividing the specific heat release rate (W/g) by the rate of temperature rise (K/s) gives a material fire parameter with the units (J/g-K) and significance of a heat (release) capacity. The heat release capacity appears to be a true material property that is rooted in the chemical structure of the polymer and is calculable from additive molar group contributions. Hundreds of polymers of known chemical composition have been tested to date, providing over 40different empirical molar group contributions to the heat release capacity. Measured and calculated heat release capacities for 80polymers agree to within ±15%, suggesting a new capability for predicting flammability from polymer chemical structure.17. Key Words Thermochemistry, Polymer flammability, Group contributions, Heat release, Fire, Combustion, Pyrolysis,Kinetics18. Distribution StatementThis document is available to the public through the National Technical Information Service (NTIS), Springfield, Virginia 22161.19. Security Classif. (of this report) Unclassified20. Security Classif. (of this page)Unclassified 21. No. of Pages 3222. PriceACKNOWLEDGEMENTSThe authors are indebted to Dr. Stanislav I. Stoliarov of the University of Massachusetts (Amherst) for performing the optimization calculations for the molar group contributions to the heat release capacity. Certain commercial equipment, instruments, materials, or companies are identified in this report in order to adequately specify the experimental procedure. This in no way implies endorsement or recommendation by the Federal Aviation Administration.TABLE OF CONTENTSPage EXECUTIVE SUMMARY vii INTRODUCTION1 THEORY1 EXPERIMENTAL3 Materials3 Methods3 RESULTS4 Calculation of Heat Release Capacity19 Heat Release Capacity and Fire Hazard20 Heat Release Capacity and Flammability21 CONCLUSION23 REFERENCES23LIST OF FIGURESFigure Page 1Schematic Diagram of the Pyrolysis-Combustion Flow Calorimeter3 2Specific Heat Release Rate Data for Several Polymers Measured in the Microscale Calorimeter5 3Calculated Versus Measured Heat Release Capacities for 80 Pure Polymers19 4Average Flaming Heat Release Rate Versus Heat Release Capacity for Several Polymers21 5UL-94 Ratings Versus Measured Heat Release Capacities of Pure Polymers22 6Plot of Limiting Oxygen Index Versus Measured Heat Release Capacity22LIST OF TABLESTable Page1.Polymer Structure and Values Derived From Pyrolysis-Combustion FlowCalorimetry62.Structural Groups and Their Molar Contribution to the Heat Release Capacity183. Group Contributions Used in the Calculation of the Heat Release Capacity ofBisphenol-A Epoxy20EXECUTIVE SUMMARYSpecific heat release rate is the molecular-level fire response of a burning polymer. The Federal Aviation Administration (FAA) obtains the specific heat release rate of milligram samples by analyzing the oxygen consumed by complete combustion of the pyrolysis gases during a linear heating program. Dividing the specific heat release rate (W/g) by the rate of temperature rise (K/s) gives a material fire parameter with the units (J/g-K) and significance of a heat (release) capacity. The heat release capacity appears to be a true material property that is rooted in the chemical structure of the polymer and is calculable from additive molar group contributions. Hundreds of polymers of known chemical composition have been tested to date, providing over 40 different empirical molar group contributions to the heat release capacity. Measured and calculated heat release capacities for over 80 polymers agree to within ±15%, suggesting a new capability for predicting flammability from polymer chemical structure.INTRODUCTIONThe additivity of molar group contributions to the physical and chemical properties of polymers is the basis of an empirical methodology for relating chemical structure to polymer properties [1-3]. The early work in this area [4] focused on calculating heats of combustion from the individual atoms comprising small molecules. However, performing calculations for large (polymer) molecules based on the interactions of the individual atoms can prove to be very difficult [2]. A simpler approach to correlating polymer chemical structure with properties is to group the atomic contributions into characteristic structural elements (e.g., –CH3), determine the value of the group contribution to the property of interest parametrically, and add these group contributions according to their mole fraction in the polymer repeat unit. This method has been used to relate the chemical structure of polymers to their thermal, chemical, optical, and mechanical properties with excellent results [1-3]. Of particular interest in the present context is the ability to predict thermal stability parameters (pyrolysis activation energy, thermal decomposition temperature, char/fuel fraction) from additivity of polymer molar group contributions [1].Prerequisite to any structure-property correlation is the ability to identify and reproducibly measure the intrinsic property of interest. In the area of polymer flammability, no single material property has correlated with fire performance, nor does any test measure fire performance unambiguously because burning rate, ignitability, flammability, and heat release rate are not intrinsic properties. Rather, they are extrinsic quantities resulting from the reaction of a macroscopic polymer sample to a severe thermal exposure. Because the sample size in a flammability or fire test is orders of magnitude larger than the chemical process zone [5-7], heat-and mass-transfer dominate the fire response. Thus, an intrinsic material property for use by scientists in designing fire-resistant polymers is not obtainable from standard fire or flammability tests.Recently, a material fire parameter [5-7] (the heat release capacity) has been identified that appears to be a good predictor of the fire response and flammability of polymers. A quantitative laboratory pyrolysis-combustion method for directly measuring the heat release capacity has been reported [8-10]. This report presents experimental data which suggests that heat release capacity is the material property that correlates polymer structure and fire behavior.THEORYThe solid-state thermochemistry of flaming combustion [5-7] reveals a material fire parameter that has the units (J/g-K) and significance of a heat (release) capacity,η=(1)cpThe heat release capacity is a combination of thermal stability and combustion properties, each of which is known to be calculable from additive molar group contributions [1]. The component material properties are the heat of complete combustion of the pyrolysis gases, h c o(J/g); the weight fraction of solid residue after pyrolysis or burning, µ(g/g); the global activation energyfor the single-step mass loss process, pyrolysis, E a (J/mole); and the temperature at the peak mass loss rate, T p (K), in a linear heating program at constant rate, β (K/s). The constants in equation 1 are the natural number e and the gas constant R. Equation 1 shows the heat release capacity to be a particular function of thermal stability and combustion properties, each of which is known to be calculable from additive molar group contributions [1]. Consequently, ηc itself is a material property and should be calculable from the same (or similar) molar groups as the component properties as long as there are no interactions between the chemical structural units. From this assumption of group additivity and the postulate that for a polymer repeat unit of molar mass M, there is a molar heat release capacity ψ with units of J/mole-K whose functional form is equation 1 but with the thermal stability and combustion properties written as molar quantities, H, V, E, and Y/M in place of h c o, (1-µ), E a and T p, respectively. If each chemical group i in the polymer adds to the component molar properties according to its mole fraction n i in the repeat unitΨ=H V EeR(Y/M)2=(2)with H i, V i, E i, Y i, and M i the molar heat of combustion, mole fraction of fuel, molar activation energy, molar thermal decomposition function [1], and molar mass of component i, respectively. Expanding the summations in equation 2 and retaining only the noninteracting terms for which i = j = k … (i.e., neglecting terms containing products and quotients with mixed indices),Ψ=ni =niΨi ΣiΣi(3)Equation 3 shows that there is a molar group contribution to the heat release capacity ψi that adds according to its mole fraction in the repeat unit of the polymer. If N i and M i are the number of moles and molar mass, respectively, of group i in the polymer having repeat unit molar mass Mn i =NiNiΣiand M=n i M iΣi=NiNiΣiMiΣithen the heat release capacity on a mass basis isηc =ΨM=niΨiΣiniMiΣi=NiΨiΣiNiMiΣi(4)Equations 2 through 4 provide the physical basis for an additive heat release capacity function, but the values of the molar contributions of chemical groups must be derived empirically (i.e., experimentally). To this end, the heat release capacities of more than 200 polymers with known chemical structure have been measured using the measurement technique described below and these experimental values have been used to generate over 40 group contributions[11 and 12].EXPERIMENTALMATERIALS .Polymer samples were unfilled, natural, or virgin-grade resins obtained from Aldrich Chemical Company, Scientific Polymer Products, or directly from manufacturers. Oxygen and nitrogen gases used for calibration and testing were dry, >99.99% purity grades obtained from Matheson Gas Products.METHODS .A pyrolysis-combustion flow calorimeter (PCFC) [8-10] was used for all experiments (see figure 1).FIGURE 1. SCHEMATIC DIAGRAM OF THE PYROLYSIS-COMBUSTIONFLOW CALORIMETERIn this device, a pyrolysis probe (Pyroprobe 2000, CDS Analytical) is used to thermally decompose milligram-sized samples in flowing nitrogen at a controlled heating rate. The samples are heated at a constant rate (typically 4.3 K/s) from a starting temperature which is several degrees below the onset degradation temperature of the polymer to a maximum temperature of 1200 K (930°C). The 930°C final temperature ensures complete thermal degradation of organic polymers so that the total capacity for heat release is measured during the test and equation 1 applies. Flowing nitrogen sweeps the volatile decomposition products from the constant temperature (heated) pyrolysis chamber, and oxygen is added to obtain a nominal composition of 4:1, N 2:O 2, prior to entering a 900°C furnace for 60 seconds to effect complete nonflaming combustion. The combustion products (carbon dioxide, water, and possibly acid gases) are then removed from the gas stream using Ascarite™ and Drierite™ scrubbers. Themass flow rate and oxygen consumption of the scrubbed combustion stream are measured using a mass flowmeter and zirconia oxygen analyzer (Panametrics Model 350), respectively.The specific heat release rate Q c in the pyrolysis-combustion flow calorimeter is determined from oxygen consumption measurements by assuming that 13.1 kJ of heat is released per gram of diatomic oxygen consumed by combustion [13-16]. Since Q c is equal to the fractional mass loss rate multiplied by the heat of complete combustion of the pyrolysis productsQ c (t )=E m o ∆O 2(t )=–h c ,v °(t )m o d m (t )d t(5)where E = 13.1 ±0.6 kJ/g-O 2, ∆O 2 is the instantaneous mass consumption rate of oxygen, m o isthe initial sample mass, h c ,v 0is the instantaneous heat of complete combustion of the volatile pyrolysis products, and dm/dt is the instantaneous mass loss (fuel generation) rate of the sample during the test. The advantage of synchronized oxygen consumption calorimetry to determine the specific heat release rate is the ease and speed of the method compared to simultaneous measurement of the mass loss rate of the solid and the heat of combustion of the pyrolysis gases [17]. At the temperature of maximum mass loss rate T p , the specific heat release rate has an analytic form [18, 5-7]Q cmax =E m o ∆O 2max =–h c ,v °(t )m o d m (t )d tmax=hc°p(6)The rate-independent heat release capacity is obtained from equation 6 by dividing the maximum specific heat release rate by the constant sample heating rate, β (K/s)ηc ≡Q c max β=E βm o ∆O 2max =p (7)The quantities measured in the test are the specific heat release rate Q c (W/g); the heat releasecapacity ηc (J/g-K) calculated from the peak specific heat release rate and the linear heating rateof the sample; the total heat released by complete combustion of the pyrolysis gases h c 0(J/g); and the residual mass fraction µ (g/g) after the test.RESULTSPyrolysis-combustion flow calorimeter data for the specific heat release rate of polyethylene (PE), polypropylene (PP), polystyrene (PS), an acrylonitrile-butadiene-styrene terpolymer (ABS), polymethymethacrylate (PMMA), polyethyleneterephthalate (PET), polyetheretherketone (PEEK), and polybenzimidazole (PBI) are shown in figure 2, horizontally shifted for clarity.Dividing the maximum specific heat release rate (W/g) measured during the test (peak height in figure 2) by the constant sample heating rate (β = 4.3 K/s in these tests) gives the heat release capacity of the polymer in units of J/g-K for materials which thermally decompose in a singlestep. Materials exhibiting multiple heat release peaks are beyond the scope of this report andwill be addressed in the future.-400-200020040060080010001200140016001800050100150200250300H e a t R e l e a s e R a t e (J /g -K )Time (seconds)FIGURE 2. SPECIFIC HEAT RELEASE RATE DATA FOR SEVERAL POLYMERSMEASURED IN THE MICROSCALE CALORIMETER(Horizontally shifted for clarity)Measured heat release capacities for more than 100 polymers with known chemical structure are shown in table 1. This data has been used to generate the group contributions shown in table 2.The molar group contributions were obtained by treating the Ψi as adjustable parameters in the linear system of equations (equation 4) for polymers with known chemical structures and measured ηc . The optimization calculation continued until the sum of the squares of the relative error between the measured ηc and the value calculated from group contributions was a minimum. The calculation converged rapidly to the unique Ψi listed in table 2 which were independent of initial estimates.T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R YT A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )T A B L E 1. P O L Y M E R S T R U C T U R E A N D V A L U E S D E R I V E D F R O M P Y R O L Y S I S -C O M B U S T I O N F L O W C A L O R I M E T R Y (C o n t i n u e d )TABLE 2. STRUCTURAL GROUPS AND THEIR MOLAR CONTRIBUTION TO THE HEAT RELEASE CAPACITY (Molar group contributions derived from asingle polymer are marked with an asterisk (*).)Figure 3 is a plot of calculated versus measured heat release capacities for over 80 polymers for which optimized Ψi were determined. The correlation coefficient between measured and predicted heat release capacities is r = 0.96 and the average relative error is ±15%.0300600900120015001800C a l c u l a t e d H R C a p a c i t y (J /g -K )Measured HR Capacity (J/g-K)FIGURE 3. CALCULATED VERSUS MEASURED HEAT RELEASE CAPACITIESFOR 80 PURE POLYMERS CALCULATION OF HEAT RELEASE CAPACITY.The following example illustrates the calculation of heat release capacity from molar group contributions for a diglycidylether of bisphenol-A (BPA epoxy) cured by anionic ring opening polymerization. This polymer has the repeat unit chemical structureCH 2CH CH 2OC CH 3CH 3O O CH 2CHCH 2O**The polymer repeat unit is comprised of six basic chemical groups, and the heat release capacity is calculated from the associated N i , M i , and Ψi for these groups, which are listed in table 3.TABLE 3. GROUP CONTRIBUTIONS USED IN THE CALCULATION OF THE HEATRELEASE CAPACITY OF BISPHENOL-A EPOXYThe molar heat release capacity is obtained by summing the group contributions according to their mole fraction in the repeat unit, then dividing by the molar mass of the repeat unit to give the heat release capacity on a mass basis in units of J/g-K.ηc=ΨM=niΨiΣiniMiΣi=NiΨiΣiNiMiΣi=204.5kJ/mole–K340g/mole=601J g–KThe predicted value of 601 J/g-K compares favorably with the measured value of 657 J/g-K for this polymer.HEAT RELEASE CAPACITY AND FIRE HAZARD.The primary indicator of the fire hazard of a material is the heat release rate in forced flaming combustion [19]. Figure 4 is a plot of the average flaming heat release rate (HRR) of 10- by 10-by 0.64-cm (≈ 80-g) samples of pure polymer measured in a fire calorimeter at an external heat flux ˙qext= 50 kW/m2 according to standard methods [20-22] versus the measured heat release capacity. Proportionality is observed between the flaming heat release rate of kilogram-sized samples and the heat release capacity of milligram-sized samples of the same polymer with slope 1.0 (kg/s)/m2/K, in general agreement with predictions for steady burning [5-7]. Consequently,ηc is a reasonable predictor of fire hazard using the physically based empirical correlation in figure 4.200400600800100012001400A v e r a g e F l a m i n g H R R (k W /m 2)Heat Release Capacity (J/g-K)250150050075010001250FIGURE 4. AVERAGE FLAMING HEAT RELEASE RATE VERSUS HEATRELEASE CAPACITY FOR SEVERAL POLYMERSHEAT RELEASE CAPACITY AND FLAMMABILITY .Flammability is taken here to mean the tendency of a thin sample of material ignited by a Bunsen burner to continue burning in the absence of a radiant heat source after removal of the burner.Self-extinguishing behavior in these tests implies a certain resistance to flame propagation, and standard methods have been developed to measure this characteristic. These flame tests are widely used to rank the burning propensity of combustible solids but they do not yield any material property information. Two common flammability test methods are the Underwriters Laboratories UL 94 test for upward vertical (V) and horizontal burning (HB) [23] and the critical oxygen concentration for flame extinguishment or limiting oxygen index (L.O.I.) in downward burning [24].In the absence of an external heat flux from a radiant heater or fire, the flame heat flux at the sample tip must provide all of the thermal energy to degrade the solid polymer surface to gaseous fuel. If the flame heat flux is constant (UL 94 test) or increases in a known way with oxygen concentration (L.O.I.), the criterion for self-extinguishing behavior in these tests can be formulated in terms of a critical heat release capacity by assuming that a minimum heat release rate (typically 100 kW/m 2) is needed to sustain flaming combustion. Such an analysis for the UL 94 test [6] indicates that polymers with ηc ≤ 300 J/g-K do not release heat at a high enough rate after removal of Bunsen burner to overcome heat losses by the sample and thus the flame cannot propagate, they self-extinguish. Thus, for pure polymers with ηc ≤ 300 J/g-K, self-extinguishing behavior (UL 94 V rating) is expected. Figure 5 contains UL 94 data [25] which shows that a transition from burning (HB) to self-extinguishing behavior (V-0) occurs in the vicinity of ηc =300 J/g-K.20040060080010001200U L -94 R a t i n gHeat Release Capacity (J/g-K)V-0V-1V-2HBFIGURE 5. UL-94 RATINGS VERSUS MEASURED HEAT RELEASECAPACITIES OF PURE POLYMERSThe criterion for self-extinguishing behavior in the L.O.I. test must take into account the fact that an increase in the oxygen concentration of the flowing gas stream in the test chamber increases the temperature (radiant heat flux) of the sample diffusion flame and, therefore, the amount of thermal energy incident on the polymer. Since the heat release rate of the sample increases with the flame heat flux, which in turn increases with oxygen concentration, an inverse relationship between ηc and the limiting oxygen concentration is expected and observed, as shown in the L.O.I. data [1, 26, and 27] plotted versus ηcin figure 6.101520253035404550O x y g e n I n d e xHeat Release Capacity (J/g-K)FIGURE 6. PLOT OF LIMITING OXYGEN INDEX VERSUS MEASUREDHEAT RELEASE CAPACITYL i m i t i n g O x y g e n I n d e xAs shown in figures 5 and 6, self-extinguishing behavior in the UL 94 vertical test occurs at a lower heat release capacity (ηc= 300 ±100 J/g-K) than in the L.O.I. test (ηc = 550 ±100 J/g-K) at ambient conditions (298 K, 20% O2). The reason for this is that the L.O.I. test is a downward burning test so there is no buoyancy-driven convective preheating of the polymer by the surface flame as occurs in the UL 94 upward burning test. Since less thermal energy is deposited in the L.O.I. sample from the surface flame at ambient conditions than is deposited in the UL 94 specimen after removal of the ignition sources, the heat release rate is lower in the L.O.I. test and self-extinguishing behavior should (and does) occur at a higher heat release capacity.CONCLUSIONThe heat release capacity is a physically based material property that is a good predictor of the fire behavior and flammability of pure polymers. The heat release capacity is simply calculated for pure polymers from their chemical structure using additive molar group contributions which have been determined empirically with a high level of confidence (±15%). The proposed methodology for predicting the fire behavior and flammability of polymers from their chemical structure allows for the molecular-level design of ultra-fire-resistant polymers without the expense of synthesizing and testing new materials.REFERENCES1. D.W. Van Krevelen, Properties of Polymers, 3rd edition, Elsevier, Amsterdam, 1990.2.Jozef Bicerano, Prediction of Polymer Properties, 2nd edition, Marcel Dekker, Inc., NewYork, NY, 1996.3.M.M. Coleman, J.F. Graf, and P.C. Painter, Specific Interactions and the Miscibility ofPolymer Blends, Technomic Publishing Co., Inc., Lancaster, PA, 1991.4.S.W. Bensen, Thermochemical Kinetics, Methods for the Estimation of ThermochemicalData and Rate Parameters, John Wiley, New York, NY, 1968.5.R.E. Lyon, “Solid-State Thermochemistry of Flaming Combustion,” in Fire Retardancyof Polymeric Materials, C.A. Wilkie and A.F Grand, eds., Marcel Dekker, Inc., NY, 2000.6.R.E. Lyon, “Heat Release Capacity,” Proceedings of the 7th International Conference onFire and Materials, San Francisco, CA, 2001, pp. 285-300.7.R.E. Lyon, “Heat Release Kinetics,” Fire and Materials, 24, pp.179-186, 2000.8.R.N. Walters and R.E. Lyon, “A Microscale Combustion Calorimeter for DeterminingFlammability Parameters of Materials,” Proceedings 42nd International SAMPE Symposium and Exhibition, 42(2), pp. 1335-1344, 1997.9.R. N. Walters and R.E. Lyon, “A Microscale Combustion Calorimeter for DeterminingFlammability Parameters of Materials,” NISTIR 5904, K. Beall, ed., pp. 89-90, 1996.。

欧盟EN阻燃、防火测试标准

欧盟EN标准(阻燃、防火测试标准)EN 13238：建筑产品防火测试-基材选择的调理方法和通则EN 13238：Reaction to Fire Tests for Building Products - Conditioning Procedures and General Rules for Selection of SubstratesAbstract摘要The Construction Products Directive requires products to be tested in their end use condition which, for the purpose of substrates, could lead to an economically unrealistic large variety of tests to be carried out. This large spectrum has been reduced to a practical number of standard substrates that enables the majority of end use conditions to be represented. Rules for the selection of such substrates are also given in this standard. BS EN 13238 is for use in conjunction with European Standards covering the reaction to fire test methods for the relevant construction products.BS EN 13238 describes the conditioning procedures for test specimens which will be tested according to the European standards for reaction to fire.BS EN 13238 also covers the rules for the selection of substrates for construction products when carrying out reaction to fire tests.BS EN 13238 does not contain requirements for:∙The pre-drying of test specimens for the non-combustibility test according EN ISO 1182∙Methods of cleaning (e.g. washing) and other methods for the assessment of durability aspects, which are dealt with in the relevant product standards.EN 13501-1：建筑产品和构件的防火等级EN 13501-1：Fire classification of construction products and building elementsAbstract摘要This European Standard provides the reaction to fire classification procedure for all construction products, including products incorporated within building elements.Products are considered in relation to their end use application.This document applies to three categories, which are treated separately in this European Standard:－construction products, excluding floorings and linear pipe thermal insulation products; floorings, linear pipe thermal insulation products.EN 13823：建筑产品的对火测试反应- 单体测试EN 13823：Reaction to Fire Tests for Building Products - Bulding Products Excluding Floorings Exposed to the Thermal Attack by a Single Burning ItemAbstract摘要The Single Burning Item test can be considered as the backbone of the Euroclass system for building products. The test results are required for a classification D - B (combined with test results from EN 11925-2), for a classification A2 (combined with test results from EN ISO 1716), and sometimes for a classification A1.TEST PRINCIPLEThe specimen is exposed to a diffusive flame of 30 kW. Combustion gases are collected by an exhaust hood for analysis. This gas analysis makes it possible by oxygen depletion to calculate heat release rate from the specimen. Smoke production is assessed bymeasuring attenuation of a light beam by smoke in the exhaust duct. The burning behaviour of the specimen is observed for flame spread, and the occurrence of burning particles and droplets.以上资料由防火资源网（）防火测试中心整理或发布，需了解更多详情请登录官网，谢谢。

四川省大学英语新三级2023年考试真题

四川省大学英语新三级2023年考试真题Sichuan Province University English New Level III 2023 ExaminationPart I Listening Comprehension (20 points)Section A (10 points)Directions: In this section, you will hear 10 short conversations. At the end of each conversation, a question will be asked about what was said. Both the conversation and the question will be spoken only once. After each question, there will be a pause. During the pause, you must read the four choices marked [A], [B], [C], and [D], and decide which is the best answer. Then mark the corresponding letter on the Answer Sheet with a single line through the center.Example:You will hear:Woman: How are you doing with your paper?Man: I have to work on it this weekend.Now the conversation:Woman: When are you going to work on your paper?Man: This weekend.You will read:[A] At the exam office.[B] Next weekend.[C] This weekend.[D] In the professor's office.From the conversation, you can tell that the man will work on his paper this weekend. So you should choose [C].1. A. She will go home on Friday.B. She is moving to a new place.C. She has a heavy schedule.D. She is planning a party.2. A. They will ask the department head.B. They don’t know the answer.C. They will see the budget officer.D. They will make a decision later.3. A. The woman should return a red pen.B. Jill has already returned a pen.C. The red pen someone returned is fine.D. The man saw that pen somewhere.4. A. John is reading to leave.B. John will get there in an hour.C. John is coming soon.D. John is leaving for the office.5. A. Jane found the keys.B. The keys are not in the car.C. They can use the extra set of keys.D. Jane left the keys in the car.Section B (10 points)Directions: In this section, you will hear a passage. Read the passage and answer the questions or complete the statements. The questions and statements will be spoken only once. After you hear a question, read the four possible answers on your paper and decide which one is the best answer. Then mark the corresponding letter on the Answer Sheet with a single line through the center.In order for a country to develop and remain competitive, it must encourage entrepreneurship. Entrepreneurship brings innovation and drives economic growth. Countries with higher levels of entrepreneurship tend to have higher levels of economic development. As such, fostering an environment conducive to entrepreneurship is crucial for continued growth and prosperity.6. What does entrepreneurship bring?A. Stagnation.B. Innovation.C. Monotony.D. Conformity.7. Countries with higher levels of entrepreneurship tend to have higher levels of _______.A. technology.B. happiness.C. economic development.D. bureaucracy.As technology advances and global connectivity increases, the world of work is changing rapidly. Many traditional jobs are being replaced by automation and artificial intelligence, while new industries and career opportunities are emerging. It is essential for workers to adapt and acquire new skills to remain relevant in the evolving job market.8. What is replacing traditional jobs?A. Automation and artificial intelligence.B. Manual labor.C. Outsourcing.D. Internships.9. What is essential for workers to do in the evolving job market?A. Retire early.B. Stay in the same job.C. Adapt and acquire new skills.D. Avoid technology.Part II Reading Comprehension (40 points)Section A (15 points)Directions: In this section, there are five passages. Each passage is followed by four questions or incomplete statements. For each of them, there are four choices marked [A], [B], [C], and [D]. You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneWhat was the first color called in English?The noun orange came into the English language in the 1300s. Oranges existed long before that, but they were thought of as "yellow-red" or "red-yellow" until the modern English word was created. Why? Before that time, the color we now call orange was not regarded as distinct. It was called geoluhread meaning "yellow-red." In England, it is geoluread and in old English,ġeolurēad. Was calling orange 'red-yellow' logical? For years, geoluread was the name for this color. Then eventually, that changed and the fruit's name became the default. In the 1540s, people began to recognize an orange as a delicious fruit from Spain. From that moment on, the fruit's name became the color's name in English. Once people knew the name of the fruit, theybegan to see the color more often, and the name became associated with the color.10. What was the color orange called before the 1300s?A. Yellow-red.B. Geoluread.C. Red-yellow.D. Spain.11. Why did the color orange not have its own name before the 1300s?A. People didn't know it existed.B. It was considered too similar to red and yellow.C. It was too rare.D. It was only used for fruit.12. When did people start calling the color orange by its own name?A. In Spain.B. In the 1300s.C. In the 1540s.D. In England.13. How did the fruit's name become associated with the color?A. People painted fruit orange.B. They were named at the same time.C. The color was more noticeable once orange was a common word.D. People ate the fruit.Passage TwoWe all know that water is essential to life on Earth and often take it for granted. However, in many parts of the world, clean drinking water is scarce and precious. A lack of clean water can lead to various health problems and even death. Access to clean water is a basic human right, yet millions of people worldwide still lack it. It is important that we all make efforts to conserve water and protect water sources for future generations.14. Why is access to clean water important?A. To prevent drowning.B. To avoid earthquakes.C. To reduce pollution.D. For health and survival.15. What causes health problems in areas with a lack of clean water?A. Dirty clothes.B. Air pollution.C. Contaminated water.D. Insufficient sunlight.16. What should people do to protect water sources?A. Continue wasting water.B. Conserve water.C. Pollute water sources.D. Overuse water sources.17. Who benefits from efforts to protect water sources?A. Only future generations.B. Only people who are already sick.C. Everyone on Earth.D. Only the wealthy.Section B (25 points)Directions: In this section, there are two passages with five multiple-choice questions following each passage. Read the passages carefully and then answer the questions or complete the statements. For each question or statement, there are four choices marked [A], [B], [C], and [D]. You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneTeaching children the value of money from a young age is important for their financial literacy and future financialwell-being. One way to do this is through pocket money or allowance. Giving children a set amount of money regularly teaches them the concept of budgeting, saving, and spending wisely. It also helps them understand the value of hard work and the importance of making choices.18. What does teaching children about money from a young age lead to?A. Financial irresponsibility.B. Future financial success.C. Laziness.D. Financial illiteracy.19. What does giving children pocket money teach them?A. How to waste money.B. The importance of saving it all.C. The concept of budgeting.D. The value of borrowing money.20. What is one benefit of giving children pocket money?A. It teaches them to steal.B. It helps them understand the value of hard work.C. It encourages them to make careless choices.D. It makes them dependent on others.21. Why is teaching children about money important?A. So they will become bankers.B. So they can buy expensive things.C. So they can make informed financial decisions.D. So they will depend on their parents.22. How does giving children pocket money help them?A. They learn to buy everything they want.B. They are encouraged to save their money.C. Budgeting is unnecessary.D. They understand the value of laziness.Passage TwoWhat is global warming?Global warming refers to the long-term heating of the planet. It is mainly caused by human activities that release heat-trapping gases into the atmosphere. The most significant of these is carbon dioxide, which is released when we burn fossil fuels like coal, oil, and gas for energy. The greenhouse effect is the mechanism behind global warming. Nature uses the greenhouse effect to keep our planet at a comfortable temperature. However, human activities have overloaded the atmosphere withheat-trapping gases, causing the planet to heat up at an alarming rate.23. What causes global warming?A. The sun.B. Human activities.C. The planet's core.D. The moon.24. What is the main heat-trapping gas released by human activities?A. Carbon dioxide.B. Oxygen.C. Nitrogen.D. Water vapor.25. What is the greenhouse effect?A. The cooling of the planet.B. A mechanism that traps heat in the atmosphere.C. The heating of the atmosphere.D. An effect that sends greenhouse gases into space.26. What does nature use the greenhouse effect for?A. To heat the planet.B. To cool the planet.C. To keep the planet at a comfortable temperature.D. To cause rapid climate change.27. What has caused human activities to overload the atmosphere with heat-trapping gases?A. Too much rain.B. Too many cars.C. Burning fossil fuels.D. The sun's radiation.Part III Vocabulary and Structure (20 points)Directions: There are 40 incomplete sentences in this part. For each sentence, there are four choices marked [A], [B], [C], and [D]. Choose the best answer to complete the sentence and mark the corresponding letter on the Answer Sheet with a single line through the center.28. If only he _______ to me about the problem sooner.A. had spokenB. speaksC. speakD. spoke29. I'll call you _______ I arrive.A. whenB. whileC. tillD. where30. The concert is _______ to be delayed due to the bad weather.A. planB. plansC. planningD. planned31. She gave him all her money _______ a gift.A. forB. withC. asD. of32. His car went out of control and _______ on the road.A. skidB. slipsC. skiddedD. slipping33. The manager asked her _______ the report by the end of the week.A. finishesB. finishedC. to finishD. finishing34. Some species of wildlife are in danger _______ extinction.A. fromB. toC. ofD. for35. Will you please help me move this _______ off the table?A. stuffB. troubleC. trashD. thing36. I _______ if you would help me with this project.A. askedB. is askedC. askingD. ask37. The teacher asked the students to _______ the meaning of the word.A. guessB. discussionC. studyD. decide38. Don't worry, I will _______ the problem as soon as possible.A. solveB. resolveC. dissolveD. involve39. The cost of living in the city is much higher _______ in the countryside.A. thanB. toC. fromD. as40. If you need any help, please _______ hesitate to ask.A. wouldn'tB. shouldC. mightD. don'tPart IV Reading Comprehension (40 points)Section A (15 points)Directions: There are four passages in this section. Each passage is followed by some questions or unfinished sentences.For each of them, there are four choices marked [A], [B], [C], and [D]. You should decide on the best choice and mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneHealth and HappinessHealth and happiness are closely related. When you are healthy, you feel good mentally and physically. Likewise, happiness boosts your immune system and makes you more likely to take care of yourself and stay healthy. People who are happier tend to live longer and have a higher quality of life. Additionally, positive emotions have a calming effect on the body and reduce stress levels.41. What is the relationship between health and happiness?A. They are unrelated.B. They are not related at all.C. They are closely related.D. Health leads to unhappiness.42. How do positive emotions affect the body?A. They have no effect on the body.B. They increase stress levels.C. They reduce stress levels.D. They make people sick.43. Do happy people tend to live longer?A. No, they have shorter life spans.B. No, it has no effect on their lifespan.C. Yes, they live longer.D. Only if they are healthy.44. Why does happiness boost the immune system?A. It weakens the immune system.B. It has no effect on the immune system.C. It strengthens the immune system.D. It makes people sick.Passage TwoModern TechnologyModern technology has changed the way we live, work, and communicate. While technology has many benefits, such as increasing efficiency and convenience, it has also brought about challenges and concerns. In today's digital world, people are constantly connected through smartphones and social media, leading to issues like information overload and decreasedface-to-face communication.45. How has modern technology changed the way we live?A. It has no effect on our daily lives.B. It has made our lives more difficult.C. It has made our lives easier and more connected.D. It has disconnected us from each other.46. What are some benefits of modern technology?A. Decreased efficiency.B. Information overload.C. Convenience and efficiency.D. Lack of connectivity.47. What are some challenges brought about by modern technology?A. Increased face-to-face communication.B. Decreased information overload.C. Greater personal connections.D. Decreased face-to-face communication.48. How are people connected in today's digital world?A. Through physical letters.B. Through smartphones and social media.C. Through email.D. Through newspapers.Passage ThreeInternational TravelInternational travel has become more accessible and popular in recent years. With advancements in transportation and technology, people can travel to different countries more easily and affordably. Traveling abroad allows individuals to experience new cultures, languages, and cuisines, as well as broaden their perspectives and gain new insights.49. What has made international travel more accessible?A. The internet.B. Transportation and technology advancements.C. Language barriers.D. Lack of interest.50. What can people experience through traveling abroad?A. Only new languages.B. Only new cuisines.C. New cultures, languages, and cuisines.D. Nothing new.51. How has international travel changed in recent years?A. It has become less popular.B. It has become more expensive.C. It has become more accessible and affordable.D. It has become restricted.52. What can individuals gain from traveling abroad?A. Nothing.B. Language skills.C. New insights and perspectives.D. Disinterest.Passage FourSocial mediaSocial media has revolutionized the way people communicate, connect, and share information. Platforms like Facebook, Twitter, and Instagram allow individuals to connect with friends, family, and strangers from around the world. While social media has many benefits, such as instant communication and easy access to information, it also presents risks like cyberbullying and privacy concerns.53. How has social media revolutionized communication?A. It has had no impact on communication.B. It has made communication more difficult.C. It has revolutionized the way people communicate.D. It has made communication less efficient.54. What can individuals do on social media platforms?A. Nothing.B. Instant communication.C. Connect with friends and family.D. Only share information.55. What are some risks associated with social media?A. No risks at all.B. Cyberbullying and privacy concerns.C. Increased privacy.D. Only benefits.56. What are some benefits of social media?A. No benefits.B. Instant communication and easy access to information.C. Decreased communication.D. Increased cyberbullying.Section B (25 points)Directions: In this section, there are two passages with five multiple-choice questions following each passage. Read the passages carefully and then answer the questions or complete the statements. For each question or statement, there are four choices marked [A], [B], [C], and [D]. You should decide on thebest choice and mark the corresponding letter on the Answer Sheet with a single line through the center.Passage OneThe Benefits of ExerciseRegular exercise has many benefits for both the body and mind. Physical activity can help improve cardiovascular health, build muscle strength, and maintain a healthy weight. Exercise also releases endorphins, which are natural mood lifters that can reduce stress and anxiety, leading to better mental health.57. What are some benefits of regular exercise?A. Increased stress and anxiety.B. Decreased cardiovascular health.C. Improved cardiovascular health and mental health.D. Lower muscle strength.58. What does physical activity help with?A. Weakening cardiovascular health.B. Building muscle weakness.C. Improving cardiovascular health and building muscle strength.D. Increasing weight.59. How does exercise affect mental health?A. It has no effect on mental health.B. It causes stress and anxiety.C. It reduces stress and anxiety and improves mental health.D. It increases stress and anxiety.60. What are endorphins?A. Chemicals that cause stress.B. Natural mood lifters.C. Harmful substances.D. Muscle builders.61. Why can exercise benefit mental health?A. Because it increases stress levels.B. Because it doesn't affect mental health.C. Because it releases endorphins.D. Because it causes anxiety.Passage TwoThe Importance of SleepSleep is essential for overall health and well-being. Getting an adequate amount of quality sleep is crucial for physical and mental health. Lack of sleep can lead to various health problems, including impaired cognitive function, decreased immune function, and。

材料燃烧特性Flammability Hazard of Materilas

Daniel Madrzykowski, P.E., is an engineer with the fire fighting technology group, Fire Research Division, Building and Fire Research Laboratory, National Institute of Standards and Technology. He is a member of NFPA’s Technical Committee on Residential Sprinkler System and Technical Committee on Fire and Explosion Investigation. He is chair of NFPA’s Research Section. David W. Stroup, P.E., is a fire protection engineer with the fire-fighting technology group, Fire Research Division, Building and Fire Research Laboratory, National Institute of Standards and Technology. He is a member of NFPA’s Technical Committee on Alternative Approaches to Life Safety and Technical Committee on Sprinkler System Discharge Criteria.
2-31
2-32 SECTION 2 ■ Basics of Fire and Fire Science

燃气轮机英文词汇[整理文档]

燃气轮机词汇表（A-I）(2007-07-02 20:36:14)转载英文xxAAcceptance test 验收实验Actual enthalpy drop (enthalpy rise)实际焓降（焓增）Actuating oil system 压力油系统Aero-derivative gas turbine, aircraft-derivative gas turbine 航空衍生（派生）型燃气机轮Air charging system 空气冲气系统Air film cooling 气膜冷却Air intake duck 进气道Alarm and protection system 报警保护系统Annulus drag loss 环壁阻力损失Area heat release rate 面积热强度Aspect ratio 展弦比Atomization 雾化Atomized particle size 雾化细度Automatic starting time of gas turbine 燃气机轮的自动起动时间Auxiliary loads 辅助负荷Availability 可用性Average continuous running time of gas turbine 燃气机轮平均连续运行时间Axial displacement limiting device 轴向位移保护装置Axial flow turbine 轴流式透平Axial thrust 轴向推力BBase load rated output 基本负荷额定输出功率Black start 黑起动Blade 叶片Blade 叶片Blade height 叶（片）高（度）Blade inlet angle （叶片）进口角Blade outlet angle （叶片）出口角Blade profile 叶型Blade profile thickness 叶型厚度Blade root xxBleed air/extraction air 抽气Blow-off 放气Blow-off value 放气阀Burner outlet temperature 透平进口温度By-pass control 旁路控制By-pass control 旁路控制CCamber angle 叶型转折角Camber line 中弧线Carbon deposit 积碳Casing 气缸Cascade xxCenter support system 定中系统Centripetal turbine 向心式（透平）Choking 堵塞Choking limit 阻塞极限Chord 弦长Closed-cycle 闭式循环Cogeneration 热电联供Cold starting 冷态起动Combined cycle 联合循环Combined cycle with multi-pressure level Rankine cycle 多压朗肯循环的联合循环Combined cycle with single pressure level Rankine cycle 单压朗肯循环的联合循环Combined supercharged boiler and gas turbine cycle 增压锅炉型联合循环Combustion chamber 燃烧室Combustion intensity 燃烧强度Combustion zone 燃烧区Combustion efficiency 燃烧室效率Combustion inspection 燃烧室检查Combustion outer casing 燃烧室外壳Combustion outlet temperature 透平进口温度Combustion specific pressure loss 燃烧室比压力损失Compactness factor 紧凑系数Compressor 压气机Compressor characteristic curves 压气机特性线Compressor disc 压气机轮盘Compressor input power 压气机输入功率Compressor intake anti-icing system 压气机进气防冰系统Compressor rotor 压气机转子Compressor turbine 压气机透平Compressor washing system 压气机清洗系统Compressor wheel 压气机叶轮Constant power operation 恒功率运行Constant temperature operation 恒温运行Control system 控制系统Convection cooling 对流冷却Cooled blade 冷却叶片Cooling down 冷却盘车Corrected flow 折算流量Corrected output 折算输出功率Corrected speed 折算转速Corrected thermal efficiency 折算热效率Critical speed 临界转速Critical speed of rotor 转子临界速度Cross flame tube/inter-connector/cross fire tube/cross light tube 联烟管confidence interval 置信区间DDead band 迟缓率Dead center 死点Deep stall 渐进失速Degree of reaction 反动度Design condition 设计工况Deviation angle 落后角Diaphragm 隔板Diffuser 扩压器Dilution of rotation 旋转方向Disc-coupled vibration 轮系振动Disc-friction loss 轮盘摩擦损失Dual fuel nozzle 双燃料喷嘴Dual fuel system 双燃料系统Dynamic balancing 动平衡EElectro-hydraulic control system 电液调节系统Enclosures 罩壳End plate 端板Energy effectiveness 能量有效度Equivalence ratio 当量比Evaporative 蒸发冷却器Excess air ratio 过量空气比Exhaust duct 排气道Exhaust gas flow 排气流量External loss 外损失Extraction gas turbine/bled gas turbine 抽气式燃气轮机FFast start 快速起动Final temperature difference 端差Flame detector 火焰检测器Flame failure limit 熄火极限Flame-failure tripping device 火焰失效遮断装置Flame-holder 火焰稳定器Flame-out ripping device 熄火遮断装置Flexible rotor 挠性（柔性）转子Flow coefficient 流量系数Flow inlet angle 进气角Flow outlet angle 出气角Flow passage 通流部分Flow pattern 流型Flow turning angle 气流转折角Free piston turbine 自由活塞燃气轮机Front 额线Fuel coefficient 燃料系数Fuel consumption 燃料消耗量Fuel control system 燃料控制系统Fuel flow control valve 燃料流量控制阀Fuel injection pressure 燃料喷嘴压力Fuel injection pump 燃料注入泵Fuel injector 燃料喷嘴Fuel shut-off valve 燃料流量控制阀Fuel supply system 燃料供给系统Fuel treatment equipment 燃料处理设备Fuel-air ratio 燃料空气比GGas expander turbine 气体膨胀透平Gas flow bending stress 气流弯应力Gas fuel nozzle 气体燃料喷嘴Gas generator 燃气发生器Gas temperature controller 燃气温度控制器Gas turbine 燃气轮机Gas turbine power plant 燃气轮机动力装置Governing system 调节系统HHeader 联箱Heat balance 热平衡Heat consumption 热耗Heat exchanger plant 换热器板Heat exchanger tube 换热器管Heat loss 热损失Heat rate 热耗率Heat recovery steam generator/HRSG 余热锅炉Heat transfer rate of heating surface 受热表面的传热率Heat utilization 热能利用率Heater 加热器Heating surface area 受热面积High oil temperature protection device （润）滑油温过高保护装置High pressure turbine 高压透平Hollow blade 空心叶片Hot corrosion 热腐蚀Hot section inspection 热通道检查Hot starting 热态起动IIdle time 惰转时间Idling speed 空负荷转速Ignition 点火Ignition equipment 点火装置Ignition speed 点火转速Impingement cooling 冲击冷却Impulse turbine 冲动式透平Incidence 冲角Inlet air flow 进口空气流量Inlet casing(plenum)进气缸（室）Inlet condition 进气参数Inlet guide vanes 进口导叶Inlet pressure 进口压力Inlet temperature 进口温度Inner casing 内气缸Intake air filter 进口过滤器Integral(tip)shroud 叶冠Intercooled cycle 中间冷却循环（间冷循环）Intercooler 中间冷却器Intermediate pressure turbine 内燃式燃气机轮Internal efficiency 内效率Internal loss 内损失Isentropic efficiency 等熵效率Isentropic efficiency 等熵效率Isentropic power 等熵功率LLagging 保温层Leaving velocity loss 余速损失Level pressure control 基准压力调节Light-off 着火Limit power 极限功率Load dump test 甩负荷试验Load rejection test 甩负荷试验Loading time 加载时间Locking piece 锁口件Logarithmic-mean temperature difference 对数平均温差Long shank blade root 长颈叶根Low fuel pressure protection device 燃料压力过低保护装置Low oil pressure protection device （润）滑油压力过低保护装置Low pressure turbine 低压透平Lubrication system 润滑油系统MMain gear 负荷齿轮箱（主齿轮箱）Major inspection 关键（部件）检查Major overhaul xxManual tripping device 手动遮断装置Mass to power ratio(mobile applications)质量功率比（用于移动式燃气机轮）Matrix 蓄热体Maximum continuous power 最大连续功率Maximum momentary speed 飞升转速Mechanical efficiency 机械效率Mechanical efficiency 机械效率Mechanical loss 机械损失Method of modelling stage 模型级法Method of plane cascade 平面叶栅法Mobile gas turbine 移动式燃气机轮Moving blade/rotor blade 动叶片Multi-shaft gas turbine 多轴燃气机轮Multi-spool gas turbine 多转子燃气机轮NNew and clean condition 新的和清洁的状态No-load operation 空负荷运行Normal start 正常起动Number of starts 起动次数OOff-design condition 变工况Open-cycle 开式循环Operating point 运行点Outer casing 外壳Outer casing 外壳Outlet condition 出气参数Outlet guide vanes 出口导叶Outlet pressure 出口压力Outlet pressure 出口压力Outlet pressure 出口压力Outlet temperature 出口温度Outlet temperature 出口温度Outlet temperature/burner outlet temperature 燃烧室出口温度Output limit 极限输出功率Output performance diagram 输出功率性能图Overspeed control device 超速控制装置Overspeed trip device 超速遮断装置Overtemperature control device 超温控制装置Overtemperature detector 超温检测器Overtemperature protective device 超温保护装置PPackaged gas turbine 箱式燃气轮机Particle separator 颗粒分离器Peak load rated output 尖峰负荷额定输出功率Performance map/characteristic map 特性图Pitch 节距Plate type recuperator 板式回热器Polytropic efficiency 多变效率Polytropic efficiency 多变效率Power recovery turbine 能量回收透平Power turbine 动力透平Power-heat ratio 功热比Precooler 预冷器Pressure level control 压力控制Pressure ratio 膨胀比（压比）Pressure ratio 膨胀比（压比）Primary air 一次空气Primary zone 一次燃烧区Profile loss 型面损失Protection system 保护系统Protective device test 保护设备试验Purging 清吹RRadial flow turbine 径流式透平Rate of load-up 负荷上升率Rated condition 额定工况Rated output 额定输出功率Rated speed 额定转速Reaction turbine 反动失透平Recirculating zone 回流区Recuperator 表面式回热器Referred output 折算输出功率Referred speed 折算转速Referred thermal efficiency 折算热效率Regenerative cycle 回热循环Regenerator 回热器Regenerator 回热器Regenerator effectiveness 回热度Reheat cycle 再热循环Reheat factor 重热系数Relative dead center 相对死点Reliability 可靠性Reserve peak load output 备用尖峰负荷额定输出功率（应急尖峰符合额定输出功率）rigid rotor 刚性转子Rotating regenerator 回转式回热器（再生式回热器）Rotating stall 旋转失速Rotor blade loss 动叶损失Rotor blade/rotor bucket 动叶片Rotor without blades 转子体SSealing 气封Secondary air 二次空气Secondary flow loss 二次流损失Secondary zone 二次燃烧区Self-sustaing speed 自持转速Semi-base-load rated output 半基本负荷额定输出功率（中间负荷额定输出功率）Semiclosed-cycle 半闭式循环Shaft output 轴输出功率Shafting vibration 轴系振动Shell 壳体Shell and tube recuperator 壳管式回热器Silencer 消音器Simple cycle 简单循环Single-shaft gas turbine 单轴燃气机轮Site conditions 现场条件Site rated output 现场额定输出功率Soot blower 吹灰器Spacer 隔叶块Specific fuel consumption 燃料消耗率Specific power 比功率Speed changer 转速变换器Specific changer/synchronizer 转速变换器Speed governor 转速调节器Speed governor droop 转速不等率Spray cone angle 雾化锥角Stabilization time 稳定性时间Stage 级Stage efficiency 级效率Stagger angle 安装角Stall 失速Standard atmosphere 标准大气Standard rated output 标准额定输出功率Standard reference conditions 标准参考条件start 起动Starter cut-off 起动机脱扣Starting characteristics diagram 起动特性图Starting characteristics test 起动特性试验Starting equipment 起动设备Starting time 起动时间Static balancing 静平衡Stationary blade 静叶片Stationary blade loss 静叶损失Stationary gas turbine 固定式燃气机轮Stator 静子Steady-state incremental speed regulation 稳态转速增量调节Steady-state speed 静态转速Steady-state speed droop 静态转速不等率Steady-state speed regulation 静态转速调节Steam and/or water injection 蒸汽和/或水的喷注Steam injection gas turbine 注蒸汽燃气机轮Steam/water injection equipment 注蒸汽/注水设备Steam-air ratio 蒸汽空气比Steam-gas power ratio 蒸燃功比Stoichiometric fuel-air ratio 理论（化学计量）燃烧空气比Straight blade 直叶片Surge 旋转失速Surge limit 喘振边界Surge margin 喘振裕度Surge-preventing device 防喘装置Swirler 旋流器TTemperature effectiveness 温度有效率Temperature pattern factor 温度场系数Temperature ratio 温比Thermal blockage 热（悬）挂Thermal efficiency 热效率Thermal fatigue 热疲劳Thermal shock 热冲击Thermodynamic performance test 热力性能试验Throat area （叶栅）喉部面积Tip-hub ratio 轮毂比Total pressure loss coefficient 全压损失系数Total pressure loss for air side 空气侧压全损失Total pressure loss for gas side 燃气侧压全损失Total pressure recover factor 全压恢复系数Transpiration cooling 发散冷却Tube bundle/tube nest 管束Tube plate 管板Turbine 透平Turbine characteristic curves 透平特性线Turbine diaphragm 透平隔板Turbine disc 透平轮盘Turbine entry temperature 透平进口温度Turbine nozzle 透平喷嘴Turbine power output 透平输出功率Turbine reference inlet temperature 透平参考进口温度Turbine rotor 透平转子Turbine rotor inlet temperature 透平转子进口温度Turbine trip speed 燃气轮机跳闸转速Turbine trip speed 燃气轮机跳闸转速Turbine washing equipment 透平清洗设备Turbine wheel 透平叶轮Turbine gear 盘车装置Turning/barring 盘车Twisted blade 扭叶片UVVane xxVane xxVariable stator blade 可调静叶片Variable stator blade 可调静叶片Variable-geometry gas turbine 变几何燃气机轮Velocity coefficient 速度系数Velocity ratio 速比Velocity triangle 速度三角形Volumetric heat release rate 容积热强度WWheel efficiency 轮周效率Working fluid heater 工质加热器Working fluid heater efficiency 工质加热器效率21/ 21。

燃气轮机英文词汇

燃气轮机词汇表（A-I）(2007-07-02 20:36:14)转载英文xxAAcceptance test 验收实验Actual enthalpy drop (enthalpy rise)实际焓降（焓增）Actuating oil system 压力油系统Aero-derivative gas turbine, aircraft-derivative gas turbine 航空衍生（派生）型燃气机轮Air charging system 空气冲气系统Air film cooling 气膜冷却Air intake duck 进气道Alarm and protection system 报警保护系统Annulus drag loss 环壁阻力损失Area heat release rate 面积热强度Aspect ratio 展弦比Atomization 雾化Atomized particle size 雾化细度Automatic starting time of gas turbine 燃气机轮的自动起动时间Auxiliary loads 辅助负荷Availability 可用性Average continuous running time of gas turbine 燃气机轮平均连续运行时间Axial displacement limiting device 轴向位移保护装置Axial flow turbine 轴流式透平Axial thrust 轴向推力BBase load rated output 基本负荷额定输出功率Black start 黑起动Blade 叶片Blade 叶片Blade height 叶（片）高（度）Blade inlet angle （叶片）进口角Blade outlet angle （叶片）出口角Blade profile 叶型Blade profile thickness 叶型厚度Blade root xxBleed air/extraction air 抽气Blow-off 放气Blow-off value 放气阀Burner outlet temperature 透平进口温度By-pass control 旁路控制By-pass control 旁路控制CCamber angle 叶型转折角Camber line 中弧线Carbon deposit 积碳Casing 气缸Cascade xxCenter support system 定中系统Centripetal turbine 向心式（透平）Choking 堵塞Choking limit 阻塞极限Chord 弦长Closed-cycle 闭式循环Cogeneration 热电联供Cold starting 冷态起动Combined cycle 联合循环Combined cycle with multi-pressure level Rankine cycle 多压朗肯循环的联合循环Combined cycle with single pressure level Rankine cycle 单压朗肯循环的联合循环Combined supercharged boiler and gas turbine cycle 增压锅炉型联合循环Combustion chamber 燃烧室Combustion intensity 燃烧强度Combustion zone 燃烧区Combustion efficiency 燃烧室效率Combustion inspection 燃烧室检查Combustion outer casing 燃烧室外壳Combustion outlet temperature 透平进口温度Combustion specific pressure loss 燃烧室比压力损失Compactness factor 紧凑系数Compressor 压气机Compressor characteristic curves 压气机特性线Compressor disc 压气机轮盘Compressor input power 压气机输入功率Compressor intake anti-icing system 压气机进气防冰系统Compressor rotor 压气机转子Compressor turbine 压气机透平Compressor washing system 压气机清洗系统Compressor wheel 压气机叶轮Constant power operation 恒功率运行Constant temperature operation 恒温运行Control system 控制系统Convection cooling 对流冷却Cooled blade 冷却叶片Cooling down 冷却盘车Corrected flow 折算流量Corrected output 折算输出功率Corrected speed 折算转速Corrected thermal efficiency 折算热效率Critical speed 临界转速Critical speed of rotor 转子临界速度Cross flame tube/inter-connector/cross fire tube/cross light tube 联烟管confidence interval 置信区间DDead band 迟缓率Dead center 死点Deep stall 渐进失速Degree of reaction 反动度Design condition 设计工况Deviation angle 落后角Diaphragm 隔板Diffuser 扩压器Dilution of rotation 旋转方向Disc-coupled vibration 轮系振动Disc-friction loss 轮盘摩擦损失Dual fuel nozzle 双燃料喷嘴Dual fuel system 双燃料系统Dynamic balancing 动平衡EElectro-hydraulic control system 电液调节系统Enclosures 罩壳End plate 端板Energy effectiveness 能量有效度Equivalence ratio 当量比Evaporative 蒸发冷却器Excess air ratio 过量空气比Exhaust duct 排气道Exhaust gas flow 排气流量External loss 外损失Extraction gas turbine/bled gas turbine 抽气式燃气轮机FFast start 快速起动Final temperature difference 端差Flame detector 火焰检测器Flame failure limit 熄火极限Flame-failure tripping device 火焰失效遮断装置Flame-holder 火焰稳定器Flame-out ripping device 熄火遮断装置Flexible rotor 挠性（柔性）转子Flow coefficient 流量系数Flow inlet angle 进气角Flow outlet angle 出气角Flow passage 通流部分Flow pattern 流型Flow turning angle 气流转折角Free piston turbine 自由活塞燃气轮机Front 额线Fuel coefficient 燃料系数Fuel consumption 燃料消耗量Fuel control system 燃料控制系统Fuel flow control valve 燃料流量控制阀Fuel injection pressure 燃料喷嘴压力Fuel injection pump 燃料注入泵Fuel injector 燃料喷嘴Fuel shut-off valve 燃料流量控制阀Fuel supply system 燃料供给系统Fuel treatment equipment 燃料处理设备Fuel-air ratio 燃料空气比GGas expander turbine 气体膨胀透平Gas flow bending stress 气流弯应力Gas fuel nozzle 气体燃料喷嘴Gas generator 燃气发生器Gas temperature controller 燃气温度控制器Gas turbine 燃气轮机Gas turbine power plant 燃气轮机动力装置Governing system 调节系统HHeader 联箱Heat balance 热平衡Heat consumption 热耗Heat exchanger plant 换热器板Heat exchanger tube 换热器管Heat loss 热损失Heat rate 热耗率Heat recovery steam generator/HRSG 余热锅炉Heat transfer rate of heating surface 受热表面的传热率Heat utilization 热能利用率Heater 加热器Heating surface area 受热面积High oil temperature protection device （润）滑油温过高保护装置High pressure turbine 高压透平Hollow blade 空心叶片Hot corrosion 热腐蚀Hot section inspection 热通道检查Hot starting 热态起动IIdle time 惰转时间Idling speed 空负荷转速Ignition 点火Ignition equipment 点火装置Ignition speed 点火转速Impingement cooling 冲击冷却Impulse turbine 冲动式透平Incidence 冲角Inlet air flow 进口空气流量Inlet casing(plenum)进气缸（室）Inlet condition 进气参数Inlet guide vanes 进口导叶Inlet pressure 进口压力Inlet temperature 进口温度Inner casing 内气缸Intake air filter 进口过滤器Integral(tip)shroud 叶冠Intercooled cycle 中间冷却循环（间冷循环）Intercooler 中间冷却器Intermediate pressure turbine 内燃式燃气机轮Internal efficiency 内效率Internal loss 内损失Isentropic efficiency 等熵效率Isentropic efficiency 等熵效率Isentropic power 等熵功率LLagging 保温层Leaving velocity loss 余速损失Level pressure control 基准压力调节Light-off 着火Limit power 极限功率Load dump test 甩负荷试验Load rejection test 甩负荷试验Loading time 加载时间Locking piece 锁口件Logarithmic-mean temperature difference 对数平均温差Long shank blade root 长颈叶根Low fuel pressure protection device 燃料压力过低保护装置Low oil pressure protection device （润）滑油压力过低保护装置Low pressure turbine 低压透平Lubrication system 润滑油系统MMain gear 负荷齿轮箱（主齿轮箱）Major inspection 关键（部件）检查Major overhaul xxManual tripping device 手动遮断装置Mass to power ratio(mobile applications)质量功率比（用于移动式燃气机轮）Matrix 蓄热体Maximum continuous power 最大连续功率Maximum momentary speed 飞升转速Mechanical efficiency 机械效率Mechanical efficiency 机械效率Mechanical loss 机械损失Method of modelling stage 模型级法Method of plane cascade 平面叶栅法Mobile gas turbine 移动式燃气机轮Moving blade/rotor blade 动叶片Multi-shaft gas turbine 多轴燃气机轮Multi-spool gas turbine 多转子燃气机轮NNew and clean condition 新的和清洁的状态No-load operation 空负荷运行Normal start 正常起动Number of starts 起动次数OOff-design condition 变工况Open-cycle 开式循环Operating point 运行点Outer casing 外壳Outer casing 外壳Outlet condition 出气参数Outlet guide vanes 出口导叶Outlet pressure 出口压力Outlet pressure 出口压力Outlet pressure 出口压力Outlet temperature 出口温度Outlet temperature 出口温度Outlet temperature/burner outlet temperature 燃烧室出口温度Output limit 极限输出功率Output performance diagram 输出功率性能图Overspeed control device 超速控制装置Overspeed trip device 超速遮断装置Overtemperature control device 超温控制装置Overtemperature detector 超温检测器Overtemperature protective device 超温保护装置PPackaged gas turbine 箱式燃气轮机Particle separator 颗粒分离器Peak load rated output 尖峰负荷额定输出功率Performance map/characteristic map 特性图Pitch 节距Plate type recuperator 板式回热器Polytropic efficiency 多变效率Polytropic efficiency 多变效率Power recovery turbine 能量回收透平Power turbine 动力透平Power-heat ratio 功热比Precooler 预冷器Pressure level control 压力控制Pressure ratio 膨胀比（压比）Pressure ratio 膨胀比（压比）Primary air 一次空气Primary zone 一次燃烧区Profile loss 型面损失Protection system 保护系统Protective device test 保护设备试验Purging 清吹RRadial flow turbine 径流式透平Rate of load-up 负荷上升率Rated condition 额定工况Rated output 额定输出功率Rated speed 额定转速Reaction turbine 反动失透平Recirculating zone 回流区Recuperator 表面式回热器Referred output 折算输出功率Referred speed 折算转速Referred thermal efficiency 折算热效率Regenerative cycle 回热循环Regenerator 回热器Regenerator 回热器Regenerator effectiveness 回热度Reheat cycle 再热循环Reheat factor 重热系数Relative dead center 相对死点Reliability 可靠性Reserve peak load output 备用尖峰负荷额定输出功率（应急尖峰符合额定输出功率）rigid rotor 刚性转子Rotating regenerator 回转式回热器（再生式回热器）Rotating stall 旋转失速Rotor blade loss 动叶损失Rotor blade/rotor bucket 动叶片Rotor without blades 转子体SSealing 气封Secondary air 二次空气Secondary flow loss 二次流损失Secondary zone 二次燃烧区Self-sustaing speed 自持转速Semi-base-load rated output 半基本负荷额定输出功率（中间负荷额定输出功率）Semiclosed-cycle 半闭式循环Shaft output 轴输出功率Shafting vibration 轴系振动Shell 壳体Shell and tube recuperator 壳管式回热器Silencer 消音器Simple cycle 简单循环Single-shaft gas turbine 单轴燃气机轮Site conditions 现场条件Site rated output 现场额定输出功率Soot blower 吹灰器Spacer 隔叶块Specific fuel consumption 燃料消耗率Specific power 比功率Speed changer 转速变换器Specific changer/synchronizer 转速变换器Speed governor 转速调节器Speed governor droop 转速不等率Spray cone angle 雾化锥角Stabilization time 稳定性时间Stage 级Stage efficiency 级效率Stagger angle 安装角Stall 失速Standard atmosphere 标准大气Standard rated output 标准额定输出功率Standard reference conditions 标准参考条件start 起动Starter cut-off 起动机脱扣Starting characteristics diagram 起动特性图Starting characteristics test 起动特性试验Starting equipment 起动设备Starting time 起动时间Static balancing 静平衡Stationary blade 静叶片Stationary blade loss 静叶损失Stationary gas turbine 固定式燃气机轮Stator 静子Steady-state incremental speed regulation 稳态转速增量调节Steady-state speed 静态转速Steady-state speed droop 静态转速不等率Steady-state speed regulation 静态转速调节Steam and/or water injection 蒸汽和/或水的喷注Steam injection gas turbine 注蒸汽燃气机轮Steam/water injection equipment 注蒸汽/注水设备Steam-air ratio 蒸汽空气比Steam-gas power ratio 蒸燃功比Stoichiometric fuel-air ratio 理论（化学计量）燃烧空气比Straight blade 直叶片Surge 旋转失速Surge limit 喘振边界Surge margin 喘振裕度Surge-preventing device 防喘装置Swirler 旋流器TTemperature effectiveness 温度有效率Temperature pattern factor 温度场系数Temperature ratio 温比Thermal blockage 热（悬）挂Thermal efficiency 热效率Thermal fatigue 热疲劳Thermal shock 热冲击Thermodynamic performance test 热力性能试验Throat area （叶栅）喉部面积Tip-hub ratio 轮毂比Total pressure loss coefficient 全压损失系数Total pressure loss for air side 空气侧压全损失Total pressure loss for gas side 燃气侧压全损失Total pressure recover factor 全压恢复系数Transpiration cooling 发散冷却Tube bundle/tube nest 管束Tube plate 管板Turbine 透平Turbine characteristic curves 透平特性线Turbine diaphragm 透平隔板Turbine disc 透平轮盘Turbine entry temperature 透平进口温度Turbine nozzle 透平喷嘴Turbine power output 透平输出功率Turbine reference inlet temperature 透平参考进口温度Turbine rotor 透平转子Turbine rotor inlet temperature 透平转子进口温度Turbine trip speed 燃气轮机跳闸转速Turbine trip speed 燃气轮机跳闸转速Turbine washing equipment 透平清洗设备Turbine wheel 透平叶轮Turbine gear 盘车装置Turning/barring 盘车Twisted blade 扭叶片UVVane xxVane xxVariable stator blade 可调静叶片Variable stator blade 可调静叶片Variable-geometry gas turbine 变几何燃气机轮Velocity coefficient 速度系数Velocity ratio 速比Velocity triangle 速度三角形Volumetric heat release rate 容积热强度WWheel efficiency 轮周效率Working fluid heater 工质加热器Working fluid heater efficiency 工质加热器效率21/ 21。

Shielding Effects of Silica-ash Layer on the Combustion of Silicones and Their Possible Applications

FIRE AND MATERIALSFire Mater.22,69—76(1998)Shielding Eﬀects of Silica-ash Layer on the Combustion of Silicones and Their Possible Applications on the Fire Retardancy of Organic PolymersFu-Yu HshiehDow Corning Corporation,P.O.Box0994,Midland,MI48686-0994,USAThis study demonstrates the shielding eﬀects of a silica-ash layer on the combustion of silicones and their possible applications on theﬁre retardancy of organic materials.The deposited silica-ash layer,formed on the surface of silicone materials during combustion,has shielding eﬀects on the combustion of silicones.It insulates the burningsurface from the radiant heat ofﬂame,as well as from the radiant heat produced from the burning of adjacent materials.It also restricts the diﬀusion of fuels into the combustion zone and the access of oxygen to the unburnedfuels.The shielding eﬀects provide some of the fundamentals for the development of silicone-basedﬁre retardants.1998John Wiley&Sons,Ltd.INTRODUCTIONSilicone materials have been produced commerciallysince the beginning of the1940s.Over the past50years,silicone materials have grown into a multibillion-dollar industry,and are used in many applications in the con-struction,electrical,transportation,aerospace,defense,textiles,and cosmetics industries.Because of the widespectrum of applications,the studies ofﬁre safety ofsilicone materials are of great importance.Two important characteristics of burning silicone-based materials,as compared with organic-based mater-ials,are the silica ash formation and the deposition ofsilica ash on the surface of burning materials. — The amount of silica ash formation and silica ash depositiondepends on the properties of silicone materials, theoxygen concentration in burning environments, and other factors.The initial rates of silica ash formation and silica ash deposition are strongly aﬀected by the external heatﬂux.Previous studies — have shown that only a small amount of silica ash is deposited for the burning of low-molecular weight silicone oligomers (LMWS)and silicone polymers with viscosity of10cS or less(LVS).For LMWS and LVS,silica ash forms mostly in the gas phase andﬂies away with the exhaust gas stream.For the burning of silicone polymers with viscos-ity of10cS or higher(HVS),a large amount of silica ash deposits on the surface of silicone polymers.It was suggested by the previous researchers — that the depos-ited silica-ash layer could serve as a good insulating layer that reduces the incident heatﬂux by reradiating the external heatﬂux.The silica-ash layer could also serve as a diﬀusion barrier that slows down the gasiﬁcation of polymers and restricts the diﬀusion of fuels into the combustion zone and the access of oxygen to the un-burned fuels.The purposes of this study are to demonstrate theshielding eﬀects of silica-ash layer on the combustion of silicones and their possible applications on theﬁre retar-dancy of organic materials.EXPERIMENTALTest materialsThe silica-ash layers used for the study of heat-shielding eﬀects were obtained from a burned silicone elastomer. The thickness of silica-ash layers was1.5,3.5,and8mm. The silica-ash layers were prepared as round discs and their diameter was approximately1.4cm.A50cS polydimethylsiloxaneﬂuid(PDMS)was tested in a cone calorimeter to demonstrate the eﬀect of silica ash on the diﬀusion of oxygen and unburned fuels and consequently on the heat release rate of PDMSﬂuid. Polypropylene(PP,3.2mm thick)was used to study the eﬀect ofﬁre-retardant additive on the burning of organic polymer.Two slabs of PP(3.2mm thick)were stapled together to form a6.4mm thick sample.For monitoring the eﬀect ofﬁre-retardant additive on the burning of organic polymer,ﬁre-retardant additives were uniformly‘sandwiched’between the two slabs of PP,and the two slabs of PP were stapled together.The thickness of the‘sandwiched’sample was approximately7.4mm. Theﬁre-retardant additives were silica ash and a mixture of silica ash and silicone powder.The silica ash was also obtained from the burned silicone elastomer as stated above.For comparison,two slabs ofﬁre-retarded poly-propylene(3.2mm thick),with a uniformly dispersed commercialﬁre-retardant additive in the polymer,were also stapled and tested in a cone calorimeter.The com-mercialﬁre-retardant additive contained silica and sili-cone powder.Polypropylene(PP,6.4mm thick),particle board(PB, 12.7mm thick),and silica ash covered PP and PB wereFigure 1.Effect of silica-ash layer on the reduction of external heat ﬂuxes.tested in a cone calorimeter to demonstrate the eﬀect of silica ash on the reduction of incident heat ﬂuxes and subsequently the burning of organic polymers.Apparatus and test methodsThe radiant heater and water-cooled Gardon Gauge of the cone calorimeter were used to study the heat-shield-ing eﬀect of the silica-ash layer.The heat ﬂux received by the Gardon Gauge was indicated by a voltmeter.The Gardon Gauge was placed approximately 25.4mm be-low the heater.The radiant heater was turned on and heated up to a temperature which provides a predeter-mined heat ﬂux.After the predetermined heat ﬂux was set up,a round disc of silica-ash layer with diﬀerent thick-ness was placed on the Gardon Gauge and fully covered the surface of the sensor.After 5min of equilibration,the heat ﬂux received by the Gardon Gauge was recorded.To conﬁrm the validation of this methodology,an alumi-nium foil (0.254mm),which is the commonly used mater-ial for shielding samples in the cone calorimeter test,was placed on the Gardon Gauge,and the heat ﬂux received by the Gardon Gauge was recorded.It was found that the aluminium foil reduced the external heat ﬂux from 50to 2kW/m .This suggests that aluminium foil can eﬀec-tively reﬂect the heat from the heater.The ﬂammability testing was conducted in a cone calorimeter according to ASTM E 1354. The cone cal-orimeter can measure the time to ignition,heat release rate,total heat released,mass loss rate,eﬀective heat of combustion,smoke density,CO and COyields.Theheat release rate during combustion,which is generally considered to be one of the most important ﬁre proper-ties of materials,is measured by using the oxygen con-sumption principle.The principle depends on the fact that the heat of combustion of most organic materials per unit mass of oxygen consumed is essentially constant and has an average value of 13.1MJ/kg.For the burning of non-silicone materials,the mass loss rate is measured using a load cell.For the burning of silicone materials,because of the deposition of amorphous silica on thesurface of burning samples,the mass loss rate is cal-culated by dividing the heat release rate by the heat of combustion of polydimethylsiloxane.It is assumed that the heat of combustion of polydimethylsiloxane during combustion is a constant and has a value of 24.6MJ/kg;consequently,the heat of combustion of polydimethyl-siloxane per unit mass of oxygen consumed is approxim-ately 14.36MJ/kg.For silicone materials,the speciﬁc extinction area (m /kg)and the CO and COyield(kg/kg)have to be determined using the calculated mass loss rate.In the cone calorimeter test,the solid sample (100;100mm)was wrapped with an aluminium foil covering the sides and bottom and placed on a sample holder.The ﬂuid was placed into a round-ﬂat quartz dish (95mm inside diameter and 15mm in depth)and then placed on a sample holder.The sample was placed 25.4mm below the heater.The heater provides heat ﬂuxes ranging from 0to 100kW/m .The sample is ex-posed to a speciﬁc incident heat ﬂux in a horizontal orientation and burns in ambient air.In this study the solid samples were tested at 50kW/m incident heat ﬂux and the liquid sample was tested at 25kW/m incident heat ﬂux.RESULTS AND DISCUSSION Shielding eﬀects of silica-ash layerHeat-shielding eﬀect of silica-ash layer.Figure 1shows theheat-shielding eﬀect of silica-ash layer.Evidently,the external heat ﬂuxes can be reduced signiﬁcantly by the silica-ash layer deposited on the surface of silicone mater-ials.With an 8mm thick silica-ash layer,the external heat ﬂux can be reduced from 100to 14.5kW/m ;even with a 1.5mm thick silica-ash layer,the external heat ﬂux can be reduced from 100to 35.7kW/m .For the burning of a 6.4mm thick silicone elastomer,it is not unusual to ﬁnd a silica-ash layer thicker than 15mm.This implies that70F.-Y.HSHIEHFigure 2.Dependence of peak heat release rate on the external heat ﬂuxes.1,8,9the unburned silicone elastomer can be shielded very well by the silica ash.Figure 1also shows that the heat-shielding eﬀect depends on the thickness of silica-ash layer.This suggests that the heat-shielding eﬀect of silica-ash layers is not only by the radiation mode but also by the conduction mode.The white or tan silica-ash layer can reradiate the heat from external heat sources and also insulate the unburned fuel by its property of low thermal conductivity.The peak heat release rate (PHRR)of a burning mater-ial has been identiﬁed as one of the most important ﬁre parameters because it can be used in conjunction with the time to ignition to indicate the propensity to ﬂash-over. Figure 2shows the dependence of PHRR of several materials on the external heat ﬂux. As seen in Fig-ure 2,the PHRR of low-viscosity PDMS ﬂuid (1.0and 2.0cS),low molecular weight hydrocarbon (LMWH),high molecular weight hydrocarbon (HMWH),and PMMA has higher dependence on the external heat ﬂux,while the PHRR of epoxy/ﬁberglass composite,white pine,and 50cS PDMS ﬂuid has much lower dependence on the external heat ﬂux.Since the external heat ﬂux can be used to represent the size of external ﬁre;therefore,the results suggest that the PHRR of 50cS PDMS ﬂuid,epoxy/ﬁbreglass composite,and white pine has much less dependence on the size of external ﬁre.The heat release rate of a burning material can be expressed by the follow-ing equation:q "(H /¸);(q #q!q )where q is the heat release rate,Hthe eﬀective heat ofcombustion,¸the heat of gasiﬁcation,q the heat ﬂuxtransferred from the ﬂame to the surface,qthe heat ﬂuxtransferred from the external radiant heat to the surface,qthe heat loss from the surface.This equation shows that the heat release rate normal-ly increases with increasing H /¸ ,qand q ,and decreases with increasing q.This equation also revealsthat the dependence of PHRR on qstrongly depends onH /¸,and to some extent on q and q.It was re-ported by Buch that the H /¸is high for LMWS andLVS (approximately 60—110)as compared with that forpolyethylene (20).The qis low for LMWS and LVSbecause only a small amount of silica ash is deposited on the surface of polymers.These two reasons account for the high heat release rate of LMWS and LVS,and also the high dependence of PHRR on q.To someextent,the burning of LMWS and LVS is similar to that of LMWH and HMWH.For HVS the H /¸is low(approximately 7.4—8.9)as compared with that for poly-ethylene (20)and PMMA (16.8). Besides the low H /¸,HVS also has low q (26kW/m )as comparedwith that for polyethylene (54kW/m ). The low H /¸ and q ,and the high qdue to the heat-shielding eﬀect of silica-ash layer account for the low heat release rate and also the extremely low dependence of PHRR on q.It is interesting to note that the dependence of PHRR for epoxy/ﬁbreglass composite and white pine on the external heat ﬂux is also very low.The ﬁbreglass in the composite and the char formed on the surface of white pine may have a similar heat-shielding eﬀect as the silica-ash layer.Diﬀusion-barrier eﬀect of silica-ash layer.It was reported byHshieh and Buch that the char integrity (silica-ash layer integrity)played an important role in the burning of silicone materials,especially for the silicone materials burned in the intermediate and large size and in a vertical conﬁguration.The deposited silica-ash layer can serve as a diﬀusion barrier which slows down the gasiﬁcation of polymers and restricts the diﬀusion of fuels into the combustion zone and the access of oxygen to the un-burned fuels.Figure 3shows two heat release rate curves of the 50cS PDMS ﬂuid which was tested in the cone calorimeter at 25kW/m .A thick silica-ash layer (ap-proximately 5mm)was deposited on the surface in the ﬁrst minute of burning.One test was conducted without any disturbance and the other test was conducted with several disturbances.A small spatula was used to occa-ssionally open up the surface silica-ash layer to expose the unburned fuel to the radiant heat.As seen in Fig.3that with gently disturbing the silica-ash layer the heat release rate increased signiﬁcantly (see the spikes on Fig.3).This result demonstrates how the silica-ash layerSHIELDING EFFECTS OF SILICA-ASH LAYER71Figure 3.Effect of silica-ash layer on the heat release rate.Silica-ash layer acted as a diffusion barrier.Table 1.Eﬀect of silicone /silica additives on the combustion of polypropylene (PP)–Cone Calorimeter Data:tests were conducted at 50kW /m 2incident heat ﬂuxSampleT ig PHRR AHRR PMLR AMLR AEHOC ASEA ACO THR (s)(kW /m 2)(kW /m 2)(g /s ;m 2)(g /s ;m 2)(MJ /kg)(m 2/kg)(kg /kg)(MJ /m 2)PP38220770146.924.743.433770.0309221pp #5%silica ash a 35133754531.121.439.164710.0336213PP #2.5%silica ash #2.5%silicone powder b 30139855830.221.437.124190.0312227PP #5%FR additive c30105954826.018.940.945670.0338226T ig :time to ignition;PHRR:peak heat release rate;AHRR:average heat release rate;PMLR:peak mass loss rate;AMLR:average mass loss rate;AEHOC:average effective heat of combustion;ASEA:average speciﬁc extinction area;ACO:average CO yield;THR:total heat released a,bThe additive was added between two slabs of PP.cThe additive was added uniformly in PP.serves as a diﬀusion barrier and its inﬂuence on the heat release rate.Applications of shielding eﬀects on the ﬁre-retardancy of organic polymersSilicone material and its decomposed product (silica ash)could be used as a ﬁre-retardant additive or an intumes-cent ﬁre retardant.Silicone material also can be in-corporated with organic polymers to improve the ﬁre properties of organic polymers. — The heat-shielding eﬀect and the diﬀusion-barrier eﬀect of silica-ash layer have been demonstrated in the previous sections.In this study,attempts have also been made to correlate these eﬀects to the ﬁre retardancy of organic polymers in terms of ﬁre-retardant additives and intumescent ﬁre retardants.Fire-retardant additives .To study the eﬀect of ﬁre-retar-dant additives on the combustion of organic polymers,three diﬀerent types of silicone/silica additives were ad-ded to PP.The sample preparation was described in theexperimental section.The reference sample and ﬁre-re-tarded samples were tested in a cone calorimeter at 50kW/m incident heat ﬂux,and the results were sum-marized in Table 1and Figs.4—10.Figure 4shows the heat release rate data for PP and three ﬁre-retarded PP.The data clearly indicate that the PHRR for PP can be signiﬁcantly reduced (up to 52%)by adding 5%of additives.It appears that silica ash alone can function as well as a mixture of silica ash and silicone powder.This suggests that silica or the silica ash generated from the combustion of silicone powder played the most important role in the ﬁre retardancy of PP.The PP with 5%FR additive had the lowest PHRR.This probably can be ascribed to the uniform distribution of ﬁre-retardant additive in PP.Figures 5and 6show the mass loss rate data and the eﬀective heat of combustion data,respectively.With the addition of ﬁre-retardant additive the mass loss rate of PP was signiﬁcantly reduced,while the eﬀective heat of combustion remained at the same level.These results indicate that the ﬁre-retardant additive functioned most-ly in the condensed phase,not in the gas phase.It was observed that during combustion a silica-ash layer was72F.-Y.HSHIEHFigure 4.Heat release rate for polypropylene and three ﬁre-retarded poly-propylenesamples.Figure 5.Mass loss rate for polypropylene and three ﬁre-retarded poly-propylenesamples.Figure 6.Effective heat of combustion for polypropylene and three ﬁre-retarded polypropylene samples.SHIELDING EFFECTS OF SILICA-ASH LAYER73Figure 7.Speciﬁc extinction area for polypropylene and three ﬁre-retarded polypropylenesamples.Figure 8.Smoke production rate for polypropylene and three ﬁre-retarded polypropylenesamples.Figure 9.CO yield for polypropylene and three ﬁre-retarded polypropyl-ene samples.74F.-Y.HSHIEHFigure10.CO production rate for polypropylene and threeﬁre-retarded polypropylene samples.formed if the additive contained silicone powder.How-ever,the formation of this silica-ash layer did not increase the carbonaceous char yields.The total heat released(see Table1)was essentially unchanged.Visual observations during the burning of PP andﬁre-retarded PP indicate that theﬁre-retarded PP burned slower,and this was mostly due to the lower vaporization rate.The silica ash or silica-ash layer acts as a diﬀusion barrier that slows down the vaporization rate of PP.To some extent,the silica ash or silica-ash layer also heat-shields the un-burned fuels.Figures7and8show the speciﬁc extinction area data and the smoke production rate data,respectively.The smoke production rate was calculated by multiplying the smoke extinction coeﬃcient(1/m)by the smoke ﬂow rate(m /s).The results indicate that with the addition ofﬁre-retardant additive,the speciﬁc extinc-tion area was increased,while the smoke production rate was decreased.The reduction in smoke produc-tion rate was primarily due to the reduction of mass loss rate.Figures9and10show the CO yield data and CO production rate data,respectively.The CO produc-tion rate was calculated by multiplying the CO yield (kg/kg)by mass loss rate(g/s m )and surface area of the sample(m ).The CO yield forﬁre-retarded PP is about the same level as that for reference PP.This sug-gests that the combustion chemistry in the gas phase did not change signiﬁcantly.As seen in Fig.10,the CO production rate was slightly reduced with the addition of ﬁre-retardant additive.The reduction in CO production rate also can be ascribed to the reduction of mass loss rate.Recently,Gilman and co-workers reported that sil-ica gel combined with potassium carbonate is an eﬀective ﬁre retardant for a wide variety of common polymers such as polypropylene,nylon,polymethylmethacrylate, poly(vinyl alcohol),cellulose,and styrene-acrylonitrile. They found that theﬁre-retardant additive increased the carbonaceous char yield and decreased the mass loss rate and heat release rate.In this study,the increase in the carbonaceous char yield was not found for silicone/silica additive used in polypropylene.However,it is highly desirable to see the development of silicone-basedﬁre-retardant additives that can reduce theﬂammability of organic polymers not only by the shielding eﬀects(heat shielding and diﬀusion barrier)but also by the increase in the carbonaceous char yield.Intumescentﬁre retardants.To form an intumescent char on the surface of organic polymers is an eﬃcient way to reduce theﬂammability of organic polymers.If a silicone-based intumescentﬁre retardant is developed and applied on organic polymers,underﬁre condi-tions,the silicone-based intumescentﬁre retardant will burnﬁrst and form an intumescent silica layer on the surface.As discussed above,the silica-ash layer could serve as an insulating layer to heat-shield the organic polymers and also could serve as a diﬀusion barrier to slow down the gasiﬁcation and vapourization of organic polymers.To simulate this phenomena,a layer of silica ash which derived from a burned silicone elastomer was placed on the top of PP and PB.The uncovered and silica-ash covered PP and PB were tested in a cone calorimeter at50kW/m incident heatﬂux,and the results were summarized in Table2.The time to igni-tion for PP and PB was signiﬁcantly increased by the shielding of silica ash.This is another good example to demonstrate the heat-shielding eﬀect of silica ash. It appears that silica ash also had some eﬀects on the combustion of organic polymers.The silica ash re-duced the peak-and average-values of heat release rate(up to52.7%)and mass loss rate,while the aver-age eﬀective heat of combustion and total heat released were only slightly reduced.The average speciﬁc ex-tinction area for PP and PB were moderately in-creased with the addition of silica ash on the top surface.The average CO yield(kg/kg)for PP and PB remained at the similar level.In general,except the time to ignition,the eﬀects of silica ash on the burning of organic polymers are similar regardless of the location of silica ash.SHIELDING EFFECTS OF SILICA-ASH LAYER75Table2.Eﬀect of silica ash on the combustion of polypropylene(PP)and particle board(PB)-simulation of a intumescentﬁre retardant.Cone Calorimeter Data:tests were conducted at50kW/m2incident heatﬂuxSample T ig PHRR AHRR PMLR AMLR AEHOC ASEA ACO THR (s)(kW/m2)(kW/m2)(g/s;m2)(g/s;m2)(MJ/kg)(m2/kg)(kg/kg)(MJ/m2) PP33202275342.128.140.273210.0232252PP#3.3%silica ash48131854431.622.838.934060.0244248PP#7.9%silica ash7495738526.619.535.724490.0201238PB2227111123.311.512.58550.021589PB#5.7%silica ash1041738316.110.311.10850.022186 Note:Silica ash was uniformly distributed on the top surface of samples.REFERENCES1.R.R.Buch,Rate of heat release and relatedﬁre parametersfor silicones.Fire Safety J.17,1—12(1991).2.L.Lipowitz,Flammability of poly(dimethylsiloxanes).I.A.model for combustion.J.Fire Flammability7,482—503(1976).3.L.Lipowitz and M.J.Ziemelis,Flammability of poly(dimethylsiloxanes).II.Flammability andﬁre hazard proper-ties.J.Fire Flammability7,504—529(1976).4.L.Lipowitz,Fire safety properties of some transformer di-electric liquids.J.Fire Flammability15,39—55(1982).5.F.-Y.Hshieh,unpublished data(1996).6.ASTM,Standard Test Method for Heat and Visible SmokeRelease Rates for Materials and Products Using an Oxygen Consumption Calorimeter(ASTM E1354),American Society for Testing and Materials,Philadelphia,PA(1994).7.M.M.Hirschler,International Conference Fire in Buildings(Interscience),Toronto,Canada,Technomic,Lancaster,PA, pp.25—26(1989).8.F.-Y.Hshieh,S.E.Motto,D.B.Hirsch and H.D.Beeson,Flammability testing using a controlled-atmosphere cone calorimeter.Proceeding of the18th International Confer-ence on Fire Safety,Millbrae,CA,pp.299(1993).9.H.C.Tran,Wood Materials(b)Experimental Data on WoodMaterials,Heat Release in Fires,Chap.11,ed.by V.Babraus-kas and S.J.Grayson,p.361.Elsevier,New York(1992).10.F.-Y.Hshieh and R.R.Buch,Controlled-atmosphere conecalorimeter,intermediate-scale calorimeter,and cone cor-rosimeter studies of silicones.Proceedings of the23rd Inter-national Conference on Fire Safety,Millbrae,CA,pp.213 (1997).11.T.Kashiwagi,T.G.Cleary,G.C.Davis and J.H.Lupinski,A non-halogenated,ﬂame retarded polycarbonate.Proceed-ings of the International Conference for the promotion of Advanced Fire Resistant Aircraft Interior Materials,Atlantic City,New Jersey,USA,pp.175(1993).12.R.Benrashid and G.L.Nelson,Flammability improvementof polyurethanes by incorporation of a silicone moiety into the structure of block copolymers,ﬁre and polymers II: materials and tests for hazard prevention,ACS Symposium series599,ed.by G.L.Nelson,American Chemical Society, Washington,DC,p.217(1995).13.M.Hirvensalo,J.E.Robinson,T.Smith,and O.A.Wiklund,Silicon stabilised char as aﬂame barrier,ﬁre and materials.Proceedings of the4th International Fire and Materials Con-ference,Washington DC,USA,pp.245(1995).14.J.W.Gilman,S.J.Ritchie,T.Kashiwagi and S.M.Lomakin,Fire-retardant additives for polymeric materials—I.Char formation from silica gel-potassium carbonate.Fire and Ma-terials21,23—32(1997).CONCLUSIONSThis study demonstrates the shielding eﬀects of silica-ash layer on the combustion of silicones.For most of the silicone materials(i.e.silicone polymers with viscosity of 10cS or higher),the silica-ash layer insulates the burning surface from the radiant heat ofﬂame as well as from the radiant heat produced from the burning of adjacent ma-terials.The silica-ash layer also restricts the diﬀusion of fuels into the combustion zone and the access of oxygen to the unburnt fuels.The shielding eﬀects provide some of the fundamentals for the development of silicone-based ﬁre retardants.Fire-retardant additives,intumescentﬁre retardants,and silicone-modiﬁed organic polymers could be developed by using silicone materials and/or silica. Future work will be focused on the improvements of ignitability andﬁre spread of organic polymers using silicone/silicaﬁre retardants or combinations of sili-cone/silica and otherﬁre retardants.76 F.-Y.HSHIEH。