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1
Wong, Wun K. "Measurement of flammability in a closed cylindrical vessel with thermal criteria." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4965.
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Accurate flammability limit information is necessary for safe handling of gas and
liquid mixtures, and safe operation of processes using such mixtures. The flammability
limit is the maximum or minimum fuel concentration at which a gas mixture is
flammable in a given atmosphere. Because combustion occurs in the vapor phase, even
in the case of liquids the flammability limits are applicable after calculating the vapor
compositions. The body of flammability data available in the literature is often
inadequate for use with the variety of conditions encountered in industrial applications.
This is due to the scarcity of flammability data for fuel mixtures in non-standard
atmospheric conditions, and inconsistencies in flammability values provided by different
experimental methods.
This work reports on the design, construction and utilization of an apparatus
capable of measuring flammability limits for a range of conditions including fuel
mixtures, varying oxygen concentrations, and extended pressure and temperature ranges.
The flammability apparatus is a closed cylindrical reaction vessel with visual, pressure
and thermal sensors. A thermal criterion was developed for use with the apparatus based
on observations of combustion behavior within the reaction vessel. This criterion provides more detailed information about the combustion than is provided by the
pressure criterion methods.
Measured flammability limits of several hydrocarbon mixtures in air compare
well with limits obtained by open glass cylinder experiments, but not with the results of
counterflow apparatus experiments. The current results show that Le ChatelierâÂÂs rule
describes the mixture results adequately. Minimum oxygen concentrations also were
determined for methane, butane, and methane-butane mixtures and compared with
values reported in the literature. Lower flammability limits were determined for an
equimolar methane-butane mixture at varying oxygen concentrations.
Results show that the flammability data determined with thermal criteria has an
acceptable level of accuracy. Recommendations for improving apparatus are made,
based upon observations made while operating the flammability apparatus.
2
Muchai, Jesse G. "Design and operational characteristics of a gasification-combustion process : flammability model /." Thesis, This resource online, 1995. http://scholar.lib.vt.edu/theses/available/etd-03042009-040746/.
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Rowley, Jeffrey R. "Flammability Limits, Flash Points, and Their Consanguinity: Critical Analysis, Experimental Exploration, and Prediction." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2233.
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Accurate flash point and flammability limit data are needed to design safe chemical processes. Unfortunately, improper data storage and reporting policies that disregard the temperature dependence of the flammability limit and the fundamental relationship between the flash point and the lower flammability limit have resulted in compilations filled with erroneous values. To establish a database of consistent flammability data, critical analysis of reported data, experimental investigation of the temperature dependence of the lower flammability limit, and theoretical and empirical exploration of the relationship between flash points and temperature limits are undertaken. Lower flammability limit measurements in a 12-L ASHRAE style apparatus were performed at temperatures between 300 K and 500 K. Analysis of these measurements showed that the adiabatic flame temperature at the lower flammability limit is not constant as previously thought, rather decreases with increasing temperature. Consequently the well-known modified Burgess-Wheeler law underestimates the effect of initial temperature on the lower flammability limit. Flash point and lower temperature limit measurements indicate that the flash point is greater than the lower temperature limit, the difference increasing with increasing lower temperature limit. Flash point values determined in a Pensky-Martens apparatus typically exceed values determined using a small-scale apparatus above 350 K. Data stored in the DIPPR® 801 database and more than 3600 points found in the literature were critically reviewed and the most probable value recommended, creating a database of consistent flammability data. This dataset was then used to develop a method of estimating the lower flammability limit, including dependence on initial temperature, and the upper flammability limit. Three methods of estimating the flash point, with one based entirely on structural contributions, were also developed. The proposed lower flammability limit and flash point methods appear to predict close to, if not within, experimental error.
4
緒方, 佳典, Yoshinori OGATA, 和弘 山本, Kazuhiro YAMAMOTO, 博史 山下, and Hiroshi YAMASHITA. "密度変化を考慮したモデルによる部分予混合雰囲気中の火炎の燃え拡がり解析." 日本機械学会, 2007. http://hdl.handle.net/2237/9383.
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山本, 和弘, Kazuhiro YAMAMOTO, 悟. 石塚, Satoru ISHIZUKA, 敏右 平野, and Toshisuke HIRANO. "軸対称流れ場に形成される管状火炎に及ぼす回転強さの影響." 日本機械学会, 1996. http://hdl.handle.net/2237/9312.
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Tseng, Ya-Ting. "Three-Dimensional Model of Solid Ignition and Ignition Limit by a Non-Uniformly Distributed Radiant Heat Source." Case Western Reserve University School of Graduate Studies / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=case1307551796.
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7
Makris, Aristidis. "Lean flammability limits of dust-air mixtures." Thesis, McGill University, 1988. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=64086.
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8
Zhao, Fuman. "Experimental measurements and modeling prediction of flammability limits of binary hydrocarbon mixtures." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-2688.
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9
Ale, Bhakta Bahadur. "Flammability limits of gaseous fuels and their mixtures in air at elevated temperatures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0002/NQ34652.pdf.
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Kilchyk, Viktor. "Flammability limits of carbon monoxide and carbon monoxide-hydrogen mixtures in air at elevated temperatures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/MQ64999.pdf.
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Johnston, Michael C. "Growth and Extinction Limits: Ground Based Testing of Solid Fuel Combustion in Low Stretch Conditions in Support of Space Flight Experiments." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1511915506999995.
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12
Coudoro, Kodjo. "Etude expérimentale et modélisation de la propagation de flammes en milieu confiné et semi confiné." Thesis, Orléans, 2012. http://www.theses.fr/2012ORLE2005.
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Cette étude s’inscrit dans le cadre de l’évaluation du risque d’accélération de flamme en situation accidentelle. La méthodologie développée dans le cadre de l’évaluation du risque hydrogène dans l’industrie nucléaire a permis de proposer un critère permettant d’évaluer le risque d’accélération des flammes de prémélange hydrogène/air/diluants, sur la base des propriétés du mélange. L’objectif de cette étude est l’acquisition de données fondamentales relatives aux mélanges gaz naturel/air et gaz de synthèse/air puis l’extension de la méthodologie appliquée aux mélanges hydrogène/air à ces mélanges. Ainsi, trois mélanges gazeux ont été choisis et ont fait l’objet de cette étude. Il s’agit du G27 (82%CH4/18%N2), du G222 (77%CH4/23%H2), et du H2/CO (50%H2/50%CO). Au cours de ce travail les limites d’inflammabilités des mélanges ont été déterminées pour une température initiale de 300 K et une pression de 1 et 2 bars. Les vitesses fondamentales de flamme et les longueurs de Markstein ont été mesurées à différentes températures initiales (300, 330 et 360 K) et à deux pressions initiales (1 et 2 bar) pour chacun des mélanges. Une modélisation cinétique de la vitesse de flamme a été réalisée et a permis l’évaluation de l’énergie d’activation globale sur la base du modèle cinétique présentant le meilleur accord avec l’expérience. La propension des mélanges a s’accélérer fortement en présence d’obstacles a ensuite été caractérisée au cours de l’étude de l’accélération de flamme. Cette étude de l’accélération de flamme a permis de mettre en évidence que différents critères d’accélération s’appliquent selon que la flamme soit stable ou pas. Un critère permettant de prédire l’accélération de flamme a été proposée dans les deux casThe context of the current study is the assessment of the occurrence of flame acceleration in accidental situations. The methodology developed for the assessment of hydrogen hazard in the nuclear industry led to the definition of a criterion for the prediction of the acceleration potential of a hydrogen/air/dilutant mixture based on its properties. This study aims to extend this methodology to gaseous mixtures that can be encountered in the classical industry. Therefore, three mixtures were chosen: the first two are representatives of a natural gas/air mixture: G27 (82%CH4/18%N2) and G222 (77%CH4/23%H2). The third one is a H2/CO (50%H2/50%CO) mixture and represents the Syngas. During this work, flammability limits were measured at 300 K and two initial pressures (1 and 2 bar) for each mixture. Fundamental flame speeds and Markstein lengths were also measured at three initial temperatures (300, 330, 360 K) and 2 initial pressures (1 and 2 bar) for each mixtures. A kinetic modeling was performed based on three detailed kinetic models and allowed the calculation of the global activation energy on the basis of the kinetic model which showed the best agreement with the experimental data. The acceleration potential for each mixture in presence of obstacles has then been investigated. It was found that different criteria were to be applied depending on whether the flame is stable or not. A predicting criterion was proposed in both case
13
Escalante, Edwin Rios [UNESP]. "Estudo dos limites de inflamabilidade em mistura etanol-ar-diluente." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143881.
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Agência Nacional de Petróleo, Gás Natural e Biocombustíveis (ANP)
Os limites superior e inferior de inflamabilidade são as concentrações máximas e mínimas de um combustível no ar, respectivamente, na qual uma chama pode se propagar, eles são considerados ferramentas chaves na predição do fogo, avaliando a possibilidade de explosão e projeto de sistemas de proteção. Existe interesse em encontrar os limites de inflamabilidade do etanol misturado com um diluente para pressões reduzidas para o futuro uso desse biocombustível em aplicações aeronáuticas tendo em conta a altitude típica de um avião comercial (<40 000 ft.). Neste trabalho foi desenvolvido experimentalmente a inflamabilidade do combustível líquido: Etanol hidratado e utilizou-se como gás diluente o nitrogênio. A bancada experimental usada, consiste de um recipiente esférico de 20 litros como câmara de aquecimento, uma fonte de ignição por faísca localizada na parte central da câmara. O líquido foi injetado com uma seringa de precisão de 1ml de volume para logo se evaporar no interior da câmara, o nitrogênio e ar foram injetados usando pressões parciais. O método para medir a inflamabilidade foi baseado na ignição elétrica e observação visual da propagação da chama conforme norma ASTM E-681. Primeiro os limites superior e inferior de inflamabilidade foram determinados para elevada temperatura (60℃) e pressão ambiente (101,325 kPa) para comparar os resultados com os dados publicados na literatura científica. Depois procedeu-se trabalhar com pressões reduzidas (80, 60, 40 e 20 kPa) para essa mesma temperatura, finalmente foram realizados testes para uma temperatura maior (110℃) para avaliar a influência da temperatura sobre os limites de inflamabilidade de misturas etanol-ar-diluente, os resultados foram plotados como função da relação e adição de nitrogênio e esses gráficos seguem a mesma tendência de trabalhos publicados na literatura científica.
The upper and lower limits of flammability are the maximum and minimum concentrations of a fuel in the air, respectively, in which the flame can spread; they are considered key tools for predicting fire, evaluating the possibility of explosion and protection system design. There is interest in finding the flammability limits of ethanol mixed with a diluent to reduced pressure for future use this biofuel in aeronautical applications having regard the typical height of a commercial aircraft (<40, 000 ft.). In this experimental work was carried flammability of the liquid fuel: Ethanol hydrate and used as a diluent gas nitrogen. The experimental apparatus consists of a 20 liters spherical vessel as heating chamber, a spark ignition source located in the central part of the chamber. The liquid was injected with a 1 ml syringe precision volume immediately evaporates in the chamber; nitrogen and air were injected using partial pressures. The method for flammability measuring was based in both visual observation electric ignition and flame propagation as defined by ASTM E-681. First, the upper and lower flammability limits were determined to a high temperature (60 ℃) and ambient pressure (101.325 kPa) to compare the results with data published in the scientific literature. After, we proceeded to work at reduced pressures (80, 60, 40 and 20 kPa) to same temperature. Finally, tests were carried out for a higher temperature (110 ℃) to evaluate the influence of temperature on the flammability limits ethanol-air-diluent mixtures, the results were plotted as a function of the relationship and adding nitrogen and these graphs follow the same trend of papers published in scientific literature.
14
Barbosa, Jean Andrade. "Determinação experimental dos limites de inflamabilidade do farnesano, querosene de aviação e misturas em pressões reduzidas /." Guaratinguetá, 2019. http://hdl.handle.net/11449/181363.
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Orientador: Celso Eduardo TunaResumo: Com a criação de combustíveis alternativos para a redução de emissões de CO2 no setor aeronáutico, torna-se necessária a determinação de suas propriedades de segurança e, entre elas destacam-se os limites de inflamabilidade. O combustível alternativo aeronáutico, que é utilizado neste trabalho, é o farnesano, fabricado a partir da cana de açúcar, por um processo que transforma açúcar em hidrocarboneto, pela empresa Amyris, localizada em São Paulo, Brasil. O objetivo dessa dissertação é determinar experimentalmente os limites de inflamabilidade, inferior (LII) e superior (LSI) do farnesano, QAV e misturas de 10% (F10) e 50 % (F50) em massa de farnesano com o QAV a pressões reduzidas em ar. Utiliza-se uma bancada experimental, que segue a norma americana ASTM E681, para a determinação dos limites de inflamabilidade, em que se utiliza o critério visual de propagação de chama e um recipiente de vidro borosilicatado de 20,716 L. Primeiramente são determinados os limites de inflamabilidade dos combustíveis para a pressão de 101,3 kPa em temperaturas entre 140 e 220°C, comparando-se os resultados com os valores teóricos disponíveis na literatura para a validação do procedimento experimental. Em segundo lugar, são determinados os limites de inflamabilidade das amostras a pressões reduzidas como 80, 60, 40 e 20 kPa em temperaturas entre 140 e 200°C. Foram realizados, no total 636 testes para determinação dos limites de inflamabilidade, sendo a duração média, para cada teste de 20 minu... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The creation of alternative fuels to reduce CO2 emissions from the aeronautical sector needs determination of their safety properties, among which are flammability limits. farnesane is the alternative aviation fuel used in here, which has been produced from sugar cane through a conversion process known as direct sugar to hydrocarbon (DSHC) created by a company called Amyris, which is located in São Paulo, Brazil. Thereby, it is aimed to experimentally determine the flammability limits, lower (LFL) and upper (UFL) of farnesane, Jet fuel and mixtures of 10% (F10) and 50% (F50) in mass of farnesane at reduced pressures with air. For such a purpose, an experimental bench was built in accordance with American standard ASTM E681 to determine the lower flammability limits, in which flame propagation was analyzed visually through a 20.716 L borosilicate glass flask. The Flammability Limits of the fuels were initially determined at a pressure of 101.3 kPa and temperatures ranging between 140 and 220 ° C, whose results were compared with theoretical values found in literature in order to validate the experimental procedure. Afterwards, the Flammability Limits of samples were determined at reduced pressures, i.e. 80, 60, 40 and 20 kPa, and temperatures ranging between 140 and 200 ° C. 636 tests were performed altogether, the average time of each test was 20 minutes. Finally, prediction equations of flammability limits, were presented as a function of temperature
Mestre
15
Loesel, Sitar Janet V. "Turbulent burning rates of near-flammability-limit H2-air-steam mixtures." 1995. http://hdl.handle.net/1993/18967.
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Chiu, Yin-Chen, and 邱寅晨. "Flammability limit and combination gas burning behavior deviation from Le Chatelier''s Law." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/8gxqfg.
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碩士中國醫藥大學
職業安全與衛生學系碩士班
102
In 1981,Le Chateilier proposed a experimental predition equation,and today this equation has still been used and develop another application.Le Chateilier’s equation can accurately predict flammability limit of multipul combination gas.But Le Chateilier’s assumption does not included the complexity of real burning. One of the Le Chateilier’s assumption is that adiabatic flame temperature of fuel is all the same and this is the reason why the deviation caused from the Le Chateilier’s equation.More combination gas we predict,more deviation we find. In addition,the flammability limit is filled with all kinds of determination method,such as flame propagation velocity、Volume percentage concentration and pressure rise. This study will focus on the relationship between all kinds of determination method. Le Chateilier’s equation can predict accurately for most combination gas.Our study will test the flammability limit of hydrogen + hydrocarbon and air mixture gas at N.T.P. and discuss the deviation behavior. Finally made a conclusion of the relationship between flammability limit and determination method of flammability limit. In addition to academic values,the results will be applicable in preventing fires and explosions in the real process,and can reduce the risk of fire and explosion in normal operation,storage,and transportation of materials.
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Chen, Hui-Chu, and 陳惠楚. "Influence of Concentration on flammability limits of mixture." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/41427442244072305904.
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碩士中國文化大學
材料科學與奈米科技研究所
97
Inerting is the process of adding inert gas to a combustible mixture to reduce the flammability limits which is one of the important features in the development of safe practices for handling a flammable vapor or gas. Theoretical models to predict the upper/lower flammability limits of a mixture composed of flammable material which contains carbon, hydrogen and oxygen atoms and inert gas which is carbon dioxide or nitrogen are proposed in this study. Based on the fact that the inert gas in a mixture does not involve in the combustion reaction, it was derived analytically that there is a linear relation between the reciprocal of the flammability limits and the reciprocal of the molar fraction of hydrocarbon in a mixture composed of flammable material and inert gas. In this study, it is found that most flammable material are of similar values of ψU . From reported experimental results which include the cases of methane, ethane, propane, n-butane, n-pentane, n-hexane, ethylene, propylene, 1,3-butadiene, isobutylene, 1-butene, 3-methyl-1-butene, methyl alcohol, ethyl alcohol, acetone, methyl ethyl ketone, dimethyl ether, methyl formate, isobutyl formate and methyl acetate are used to examine the proposed linear relation. Thus, the proposed predicting rule could afford a reasonable value of UFL of flammable material diluted with inert nitrogen and carbon dioxide for most practical applications.
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Zhang, Yan-Chang, and 張晏昌. "The prediction model on flammability limits of organic combustible." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/71483506270097182345.
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碩士中國文化大學
材料科學與奈米科技研究所
99
In processing, transporting and storing combustible liquids and gases, people rank the flammability limits as a crucial safety index. Therefore, many researchers carry out experiments on or set up prediction models for them. In this research, we want to investigate the mixing of combustible gases and combustible gases of pure oxygen. Theoretical models to predict the upper flammability limits of mixtures that with two organic combustible gases and estimate the flammability limit in pure oxygen of combustible gases. Mixture of combustible gases based on the ability to grab oxygen relationship, developed a model to predict the upper flammability limits of mixtures, through the literature experimental data of methane - propane, methane - ethylene, methane - acetylene, methane - Isobutane and propane - n-butane to regression analysis showed that the prediction flammability limit model is apply to the five combinations. From the viewpoint of mass-energy balance and use adiabatic flame temperature of combustible gas of air to estimate flammability limit of pure oxygen, the results shown that the predicted value is close to experimental data, so this prediction model can be as a quick state to estimate the flammability limit of pure oxygen in Industry.
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Lin, Chin-Yu, and 林勁宇. "Carbon dioxide dilution effect on flammability limits for hydrocarbons." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/55994347380983070464.
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碩士中國文化大學
材料科學與奈米科技研究所
96
Flammability limits are one of the important features in the development of safe practices for handling a flammable vapor or gas. A theoretical model to predict the flammability limits of a mixture composed of hydrocarbon and carbon dioxide is proposed in this study. The main assumptions in developing the theoretical models include: (U1) the oxygen reacts completely at UFL. (U2) the stoichiometric relation of a combustion reaction occurring at UFL does not change by the presence of inert gas. (U3) the adiabatic temperature rises are the same for all limit mixture at UFL. (L1) the hydrocarbon reacts completely at LFL. (L2) the stoichiometric relation of a combustion reaction occurring at LFL does not change by the presence of inert gas; (L3) the adiabatic temperature rises are the same for all limit mixture at LFL. With aforementioned assumptions, it was derived analytically that there is a linear relation between the reciprocal of the flammability limits and the reciprocal of the molar fraction of hydrocarbon in a mixture composed of hydrocarbon and carbon dioxide. Experimental data reported in the literature, which include ten kind of hydrocarbons are then used to examine these theoretical linear relations. The coefficients of determination for these ten cases studies are all greater than 0.931 for both UFL and LFL. Thus, this theoretical conclusion was highly supported by the experimental results.
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Kutzler, Patrick M. "Flammability limits of a premixed gas with steam addition." 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2630/index.html.
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Zhao, Fuman. "Inert Gas Dilution Effect on the Flammability Limits of Hydrocarbon Mixtures." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-12-10569.
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Flammability limit is a most significant property of substances to ensure safety of chemical processes and fuel application. Although there are numerous flammability literature data available for pure substances, for fuel mixtures these are not always available. Especially, for fuel mixture storage, operation, and transportation, inert gas inerting and blanketing have been widely applied in chemical process industries while the related date are even more scarce.
Lower and upper flammability limits of hydrocarbon mixtures in air with and without additional nitrogen were measured in this research. Typically, the fuel mixture lower flammability limit almost keeps constant at different contents of added nitrogen. The fuel mixture upper flammability limit approximately linearly varies with the added nitrogen except mixtures containing ethylene. The minimum added nitrogen concentration at which lower flammability limit and upper flammability limit merge together is the minimum inerting concentration for nitrogen, roughly falling into the range of 45 plus/minus 10 vol % for all the tested hydrocarbon mixtures.
Numerical analysis of inert gas dilution effect on lower flammability limit and upper flammability limit was conducted by introducing the parameter of inert gas dilution coefficient. Fuel mixture flammability limit can be quantitatively characterized using inert gas dilution coefficient plus the original Le Chatelier's law or modified Le Chatelier's law.
An extended application of calculated adiabatic flame temperature modeling was proposed to predict fuel mixture flammability limits at different inert gas loading. The modeling lower flammability limit results can represent experimental data well except the flammability nose zone close to minimum inerting concentration.
Le Chatelier's law is a well-recognized mixing rule for fuel mixture flammability limit estimation. Its application, unfortunately, is limited to lower flammability limit for accurate purpose. Here, firstly a detailed derivation was conducted on lower flammability limit to shed a light on the inherent principle residing in this rule, and then its application was evaluated at non-ambient conditions, as well as fuel mixture diluted with inert gases and varied oxygen concentrations. Results showed that this law can be extended to all these conditions.
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Wu, Siou-Yuan, and 吳修緣. "Products analysis at the flammability limits of methane by nitrogen inerting." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/87413698890514594911.
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碩士雲林科技大學
環境與安全工程系碩士班
99
In previous study, Le Chatelier’s theory has been used to calculate the flammability limits, and then this theory developed a numerical or statistical analysis to estimate the flammability limits after inerting. At this moment, almost studies are base on the theory to assume the behavior of combustion reaction after inerting. Then, it is accurate to predict and reason the flammability limits. However, researches of flammability limits for combustion behavior after inerting was not quantified in detail in the open literature. Therefore, it is a very important assignment nowadays to comprehend the combustion reaction, behavior, and mechanism of methane which explore after inerting and to proof the results of literatures. We used a 20-L-apparatus to investigate the flammability limits data under initial testing condition of 30oC and 1 atm. Methane was selected as examples, and nitrogen was used as an inert gas. With above experiments, we can obtain the flammability limit data. Furthermore, using gas chromatograph could be provided quantitative and qualitative analysis for the compositions of product. From this study, the results can be clarified and understood the combustion reaction, behavior, and mechanism of methane after inerting. On the other hand, it also matches literatures. In consequence, this study can provide some important information to reestablish a rule of flammability limit in the future. It would be helpful to make the theoretical prediction model precisely.
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LI, ZONG-HAN, and 李宗翰. "The Effect of Subatmospheric Pressures on Flammability Limits of Flammable Gases." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/v8n82u.
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碩士國立高雄科技大學
環境與安全衛生工程系
107
Flammability limits are the most important parameter for assessing the fire and explosion hazards of flammable gases and vapors. There are two limits of flammability, lower flammability limit (LFL) and upper flammability limit (UFL), which define the flammable region. Accurate flammability limit information is necessary for process operation and safe handling of chemicals. However, published data for flammability limits available in the literature is inadequate for variety of conditions in industrial processes. This is because the flammability limits were generally tested at the normal temperature and pressure. The study of subatmospheric pressure effects on flammability limits are scarce and almost unavailable. Thus, this study investigated the subatmospheric pressure effects of flammability limits for flammable gases. The experimental research was conducted in a 5-L spherical flask which was specifically designed based on the standard test method ASTM E681. The flammability limits of methane-air, propane-air, propylene-air, and 1-butene-air were measured at room temperature and initial pressures of 1.0, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.13atm. After checking the veracity of the data obtained from room temperature and 1.0atm, the work proceeded with subatmospheric pressures. The results showed that when the initial pressures decreases below 1.0atm, the flammability range of hydrocarbons decreased as the initial pressure decreased, except for methane where the LFL did not change with pressure. Furthermore, the variation of UFLs with decrease of pressure is much significant than LFLs. This result can be applied in the inherent safety design of real process, and can reduce the risk of fire and explosion in normal operation, storage, and transportation of flammable gases and vapors.
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WANG, QI-HONG, and 王其宏. "n experimental study on extinction and flammability limits of premixed flame." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/97183654792872253666.
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Chen, Kuan-Yu, and 陳冠宇. "The Study of Temperature Effects on Flammability Limits of Flammable Gases." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/30558397981724195807.
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碩士國立高雄第一科技大學
環境與安全衛生工程研究所
103
Flammability limits were one of the most important indicators to assess the flammable gases and vapors fire and explosion hazard. This study proposed a model to estimate the temperature effect on flammability limits for organic compounds made up of carbon, hydrogen and oxygen. The energy balance and constant adiabatic flame temperature were used to establish the model. In our study, the 5-L spherical flask basically follows ASTM (American society for testing and materials, ASTM) E681 method. Hydrogen, methane, propylene and 1-butene were selected as sample at temperature 50 ℃、100 ℃、150 ℃ to validate the proposed model. This study suggests that only one points are required for precisely predicting the flammable zone. Overall, the estimated results of this proposed model describe the experimental data well. In addition to academic values, the results will be applicable in preventing intrinsic safety in the real process, and can reduce the risk of fire and explosion in normal operation, storage, and transportation of materials.
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Dong, Yi-chih, and 董益銍. "Measurements of Lean Flammability Limits and Burning Velocities for Clean Coal Gasification Syngas." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/54857524308950603443.
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碩士國立中央大學
機械工程研究所
100
This thesis studies experimentally high-pressure lean syngas (hydrogen/carbon monoxide) combustion characteristics derived from the clean coal entrained-flow gasifier. Focuses are placed on measurements of lean flammability limits and laminar and turbulent burning velocities (ST and SL) for various compositions of H2/CO mixtures. Experiments are carried out in a large high-pressure, double-chamber (an inner chamber and an outer chamber) premixed turbulent combustion facility. The inner chamber applies the same design of our previous cruciform burner that was constructed by two mutually crossing cylindrical vessels, a horizontal vessel and vertical vessel, forming a cruciform shape. Using two identical frequency-controlled counter-rotating fans and perforated plates at the two ends of the horizontal vessel, an intense near-isotropic turbulent flow field can be generated in the central region of the inner chamber. As to the outer chamber, it is a large high-pressure airtight chamber used to absorb the pressure rise releasing from the inner chamber via four sensitive pressure-releasing valves. These four valves are placed symmetrically in the front and back sides of the vertical vessel. A high-speed, high-resolution CMOS camera system used to directly record flame propagation images and thus flame burning velocities can be determined from image analysis with flame strain rate calculation and the density correction. Concerning laminar premixed syngas experiments, we measure the lean flammability limits and laminar burning velocities at various equivalent ratios from ??= 0.4 ~ 1.0 with three different syngas fuel compositions, namely 50%CO/50%H2, 65%CO/35%H2 and 95%CO/5%H2, each covering an initial pressure (p) range from 1 atm to 5 atm. Results show that by increasing p, not only values of SL decrease but also lean flammability limits can be expanded. It is found that the effect of p on SL is more sensitive when ? is close to the lean flammability limit than near the stoichiometry (? = 1). As to the effect of hydrogen compositions, the higher hydrogen concentration is, the higher value of SL and the wider range of lean flammability limits. On the other hand, the effect of p on SL is diminished at higher hydrogen concentrations. For turbulent premixed syngas flames, we measure high-pressure ST of lean premixed syngas mixtures (35%H2/65%CO) at ??= 0.5 covering a wide range of pressure from p = 0.1 MPa to 1.0 MPa. Note that the present measurements differ with previous studies, because we keep the turbulent Reynolds numbers (ReT ? u?LI/?) constant by adjusting the root-mean-square turbulent fluctuation velocity (u?) and the integral length scale (LI) in proportion to the decreasing kinematic viscosity of reactants (?) at elevated pressure. Results show that, contrary to popular scenario for turbulent flames, when ReT is fixed, ST decreases similarly as SL with increasing p in minus exponential manners, ST ~ p-n, where n ≈ 0.5 almost independent of ReT. Moreover, at any fixed p, values of ST/SL increase noticeably with increasing ReT. It is found that these very scattering ST/SL data over very wide ranges of p and ReT can be merged onto a single curve having a relation of ST/u? = 0.49Da0.25, where Da is the turbulent Damkohler number. This experimental relation supports a theoretical prediction proposed by Zimont. However, such relation is different from our previous finding for lean methane mixtures where ST/u? = 0.14Da0.5 using the same facility and at the same p and ReT. We shall discuss the effects of pressure, flame instability and turbulence scale in attempt to address the aforementioned discrepancy in the exponential power constants of the Da dependence between lean syngas and methane mixtures. These results should be important when applying syngas fuels with higher hydrogen compositions to gas turbines, industrial furnaces, and other various burners.
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Lin, Shang-Chih, and 林上智. "Studies on Flammability Limits of Spray Flames and Combustion Instability of Flames in Afterburners." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/86481710566518506610.
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碩士國立成功大學
機械工程研究所
83
First,the burning characteristics of a 2-dimensional,steady, laminar flame propagating in a monodisperse,dilute sprays are conducted for methanol and ethanol burning in air. As Le>1,the flow stretch will weaken the flame intensity,and extinction. As Le<1,the flow stretch will enhance the flame intensity, and no extinction occurs. Second,we continue the prior research to investigate,using experimental approach, the characteristics of V-gutter flame.We can find 4 regions which is flashback region, stable-flame region ,unstable-flame region ,and extinction region.For stable region and unstable region,we analyze the spectrum to identify the fre- quency of combustion instability. In future,we will try to do the control of the combustion instability by adding sound wave with feedback loop.
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Chen, Shi Lu, and 陳世祿. "A Computational Study of Flammability Limits of Opposed-Jet H2/O2/CO2 Diffusion Flame." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/90280021407775428870.
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碩士長庚大學
機械工程研究所
97
A narrowband radiation model is coupled to the OPPDIF program to enable the study of 1-D opposed-jet hydrogen/oxygen/carbon-dioxide diffusion flames over the entire range of flammable stretch rates. The effects of the extinction limits and flame structure are discussed at various atmospheric pressure, temperature and concentration of carbon dioxide. In addition, The flammability limits is presented using maximum flame temperature and stretch rate as coordinates. Both the high-stretch blowoff and the low-stretch quenching limits are found. Low-stretch diffusion flame with radiation loss is unusually thin and the flame temperature is substantially lower than that computed with the non-radiation model. This large temperature drop results from the combined effect of flame radiation and hydrogen–oxygen chemical kinetics. The flammability limits and flame thickness are increasing with increasing atmospheric pressure and temperature, and the most flammability limits are extended to high-stretch, indicating the influence of the ambient pressure and temperature on the chemical reaction. The effects of carbon-dioxide dilution on hydrogen- oxygen flames show the flammability limits and flame thickness are decreasing with increasing the concentration of carbon-dioxide, and the most flammability limits are extended to low-stretch, indicating the influence of carbon-dioxide as a radiation participating medium on the low-stretch quenching limits.
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Wu, Tien-Shiang, and 吳天祥. "An Experimental Study on Extinction and Flammability Limits of Premixed Flame of Prevaporized Liquid Fuel." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/08096979785972866351.
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碩士國立臺灣大學
機械工程研究所
81
Experimental studies of the extinction mechanism and flamma- bility limits of premixed flame in a stagnation flow were made by using the symmetrical counterflow flame configuration. By mea- suring the extinction limits under various conditions, such as equivalence ratio, flame stretch rate, downstream heat loss, in- let mixture temperature and fuel type, we can yield useful in- sight on the extinction characteristics. The difference between extinction limit and flammability limit has also been discussed, and the extinction limits for nearly adiabatic, stretchless, and planar flames appear to correspond to the flammability limits of the respective mixtures. Finally, we also observed the various phenomenon caused by preferential diffusion effect. The mapping of the velocity profile was done by using the LDV instrument with 0.1-1 um MgO as seeding particles. The liquid fuels used in our experiment are heptane, iso-octane, methanol, and ethanol.
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Le, Thuy Minh Hai. "Flammability Characteristics of Hydrogen and Its Mixtures with Light Hydrocarbons at Atmospheric and Sub-atmospheric Pressures." Thesis, 2013. http://hdl.handle.net/1969.1/150966.
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Knowledge of flammability limits is essential in the prevention of fire and explosion. There are two limits of flammability, upper flammability limit (UFL) and lower flammability limit (LFL), which define the flammable region of a combustible gas/vapor. This research focuses on the flammability limits of hydrogen and its binary mixtures with light hydrocarbons (methane, ethane, n-butane, and ethylene) at sub-atmospheric pressures.
The flammability limits of hydrogen, light hydrocarbons, and binary mixtures of hydrogen and each hydrocarbon were determined experimentally at room temperature (20ºC) and initial pressures ranging from 1.0 atm to 0.1 atm. The experiments were conducted in a closed cylindrical stainless steel vessel with upward flame propagation. It was found that the flammable region of hydrogen initially widens when the pressure decreases from 1.0 atm to 0.3 atm, then narrows with the further decrease of pressure. In contrast, the flammable regions of the hydrocarbons narrow when the pressure decreases. For hydrogen and the hydrocarbons, pressure has a much greater impact on the UFLs than on the LFLs.
For binary mixtures of hydrogen and the hydrocarbons, the flammable regions of all mixtures widen when the fraction of hydrogen in the mixture increases. When the pressure decreases, the flammable regions of all mixtures narrow. The applications of Le Chatelier’s rule and the Calculated Adiabatic Flame Temperature (CAFT) model to the flammability limits of the mixtures were verified. It was found that Le Chatelier’s rule could predict the flammability limits much better than the CAFT model.
The adiabatic flame temperatures (AFTs), an important parameter in the risk assessment of fire and explosion, of hydrogen and the hydrocarbons were also calculated. The influence of sub-atmospheric pressures on the AFTs was investigated. A linear relationship between the AFT and the corresponding flammability limit is derived. Furthermore, the consequence of fire relating to hydrogen and the hydrocarbons is discussed based on the AFTs of the chemicals.
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Wooldridge, Richard Clark. "An experimental investigation of the ignition and flammability limits of various hydrocarbon fuels in a two-dimensional solid fuel ramjet." Thesis, 1987. http://hdl.handle.net/10945/22259.
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