Letteratura scientifica selezionata sul tema "Combustion du bois"
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Articoli di riviste sul tema "Combustion du bois":
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Amenan Lydie Clarisse, Mangoula-Allali, Kone Tiangoua, Messou Aman, Nikebie Koffi Olivier Fabrice e Coulibaly Lacina. "Valorisation Energetique des Dechets Agricoles : cas de la Pomme de Cajou dans le Departement de Tanda (Côte d’Ivore)". European Scientific Journal, ESJ 18, n. 27 (31 agosto 2022): 142. http://dx.doi.org/10.19044/esj.2022.v18n27p142.
Abstract (sommario):
Cette étude s’est proposée de valoriser la pomme de cajou e combustible. Le matériel est constitué de pommes de cajou séchée non carbonisée (PCSNC), pommes de cajou fermentées séchées carbonisées (PCFSC),, pommes de cajou séchées et carbonisées (PCSC), briquettes comportant 100% de pommes carbonisées et 0% de sciure de bois carbonisée (BPC100), briquettes comportant 80% de pommes carbonisées et 20% de sciure de bois carbonisée (BPC80), briquettes comportant 70% de pommes carbonisées et 30% de sciure de bois carbonisée (BPC70), briquettes comportant 60% de pommes carbonisées et 40% de sciure de bois carbonisée (BPC60). Ces combustibles ont été caractérisés en déterminant la quantité de chaleur dégagée, la durée de combustion, le temps d’ébullition, le niveau de dégagement de fumée, la masse de suie après combustion et le taux de cendres. Les valeurs obtenues pour ces paramètres ont été comparées à celles du charbon de bois. Il ressort que les quantités de chaleur dégagées par PCFNC (963 KJ) et PCSNC (943 kJ) sont relativement proches de celle (1122 kJ) du charbon de bois. Pour la durée de combustion, ce sont les briquettes et le charbon de bois témoin qui mettent plus de temps à se consumer (60 minutes, environ). Le temps le plus court d’ébullition de l’eau est obtenu avec BPC100 (10,98 minutes contre 15,45 minutes pour le charbon de bois). Les combustibles à base de pommes de cajou ont tous dégagé de la fumée et ont favorisé un dépôt de suie après la combustion contrairement au charbon de bois. Au niveau de la cendre, BPC60 et BPC70 ont produit moins de cendre (10g) que le charbon de bois (12,5g). Au vu de ces résultats, si certaines caractéristiques de la pomme de cajou sont améliorées, sa valorisation énergétique est possible.
This study intended to valorize the cashew apple or cashew nut into fuel. The material consists of cashew apples and sawdust, which allowed us to obtain 8 types of fuel. This includes dried cashew apples without carbonization (PCSNC), dried fermented cashew apples with carbonization (PCFSC), dried cashew apples with carbonization (PCSC), and briquettes with 100% carbonized apples and 0% sawdust with carbonization (BPC100), briquettes with 80% carbonized apples and 20% carbonized sawdust (BPC80), briquettes with 70% carbonized apples and 30% carbonized sawdust (BPC70), briquettes with 60% carbonized apples and 40% carbonized sawdust (BPC60). These fuels were characterized by determining the amount of released heat, combustion time, boiling time, level of smoke release, soot mass after combustion, and ash content. The values obtained for these parameters were compared with those of charcoal. The heat release of PCFNC (963 kJ) and PCSNC (943 kJ) is relatively close to that of charcoal (1122 kJ). The briquettes and the control charcoal take longer to burn (about 60 minutes, in terms of burning time. The shortest water boiling time was obtained with BPC100 (10.98 minutes versus 15.45 minutes for charcoal). Cashew apple fuels all gave off smoke and promoted soot deposition after combustion. This was not the same as charcoal’s case. Regarding ash generation, BPC60 and BPC70 produced less ash (10g) than charcoal (12.5g). Considering these results, if some characteristics of the cashew apple are improved, its energy valorization is possible.
2
Bernard, C., M. L. Rabot-Querci, Y. Rogaume, C. Rogaume e A. Zoulalian. "Optimiser la combustion pour un développement durable du bois-énergie". Oil & Gas Science and Technology 61, n. 2 (marzo 2006): 203–11. http://dx.doi.org/10.2516/ogst:2006014x.
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Robert, L. "Épuration des polluants issus de la combustion domestique du bois". Oil & Gas Science and Technology 61, n. 2 (marzo 2006): 213–23. http://dx.doi.org/10.2516/ogst:2006015x.
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KASEKETE, Désiré Katembo, Nils BOURLAND, Michel GERKENS, Dominique LOUPPE, Jolien SCHURE e Jean-Pierre MATE. "Bois-énergie et plantations à vocation énergétique en République démocratique du Congo : cas de la province du Nord-Kivu – Synthèse bibliographique". BOIS & FORETS DES TROPIQUES 357 (1 ottobre 2023): 5–28. http://dx.doi.org/10.19182/bft2023.357.a36927.
Abstract (sommario):
L’énergie d’origine ligneuse est largement utilisée en République démocratique du Congo (RDC) où elle satisfait plus de 90 % des besoins énergétiques des ménages et de certains professionnels. Cette étude dresse l’état des lieux des connaissances sur la filière bois-énergie et les plantations dédiées en RDC, en particulier dans la province du Nord-Kivu, et cherche à relever les éventuelles lacunes dans l’information qui nécessiteraient d’être comblées. La revue des études a révélé un caractère fragmentaire de la recherche sur la filière. La consommation en bois-énergie n’est connue que pour quelques villes, avec des estimations questionnables pour certaines d’entre elles dont Butembo au Nord-Kivu. L’extraction du bois-énergie se fait dans toutes les zones boisées accessibles dont les forêts naturelles, les terres agricoles et les plantations forestières. Certaines pratiques sont illégales et ont lieu dans les aires protégées. Depuis les années 1980, environ 69 400 ha de plantations à vocation énergétique ont été réalisés en RDC par 15 projets. Ces plantations sont encore marginales, trop jeunes et incapables de satisfaire la demande actuelle ou future. Elles fourniraient, combinées avec les plantations initiées hors projets, environ 9, 30, 32 et 54 % du bois-énergie consommé respectivement à Kinshasa, Bukavu, Goma et Butembo. À part celles sur les plantations du plateau Batéké et du Nord-Kivu, il n’existe pas encore de publications scientifiques sur les autres plantations à vocation énergétique de la RDC. Pour gérer durablement la ressource et sécuriser les approvisionnements, des actions sont indispensables en ce qui concerne prioritairement : la diversification des sources d’approvisionnement en bois-énergie, à travers notamment de larges programmes de plantations forestières et agroforestières ainsi que l’aménagement des forêts naturelles ; l’amélioration des techniques d’exploitation du bois et de sa carbonisation ; la réduction de la consommation en bois-énergie grâce aux foyers de combustion améliorés et au recours à des énergies alternatives au bois. Cela exige aussi la formalisation et la structuration de la filière bois-énergie suivant des dispositions réglementaires spécifiques à édicter. Des recherches complémentaires sont nécessaires en vue d’améliorer l’exploitation, la transformation et d’optimiser l’utilisation du bois-énergie.
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Augou, Ovo Sandrine Flora, Souleymane Ouattara, Conand Honoré Kouakou, Koffi Clément Kouadio, Aka Alexandre Assande e Edjikémé Emeruwa. "Influence de la pression de compactage sur les caractéristiques physiques et la durée de combustion de combustible à base de sciure de bois et de liant végétal". Matériaux & Techniques 108, n. 4 (2020): 404. http://dx.doi.org/10.1051/mattech/2021001.
Abstract (sommario):
Ce travail s’inscrit dans le cadre du recyclage des déchets industriels (sciure de bois). L’élaboration du charbon de bois et la production de la sciure de bois par les scieries en Côte d’Ivoire entraînent des problèmes environnementaux, climatiques et sanitaires. La présente étude propose, une solution palliative à ces problèmes à partir de l’élaboration de charbon dénommé biocharbon, réalisé avec ces déchets. Cependant, le problème prédominant est la pression de compactage optimale pour confectionner les combustibles. Le but de cette étude est de déterminer cette pression de compactage. Les matières premières utilisées sont la sciure de bois de l’Iroko (Chlorophora excelsa) carbonisée et l’amidon de manioc (Manioht exculenta) transformé en empois d’amidon (EA). Pour les agglomérer, quatre formulations de rapport EA/Sb égale à 0,75, 0,87, 1 et 1,125 sont employés avec une pression de compactage variant de 100 à 500 kPa par pas de 100. Les résultats obtenus à partir des essais montrent que les biocharbons élaborés avec la formulation de rapports 0,75 ne sont pas bien consolidés quelque soit la pression de compactage. Ceux de rapport 1,125 ne nécessitent pas de pression de compactage et ceux de rapport 0,87 et 1 se consolident à 500 kPa. Concernant la masse volumique, elle augmente avec la pression de compactage et on observe une perte de matière pour le rapport 1,125 lorsque la pression est supérieure à 300 kPa. Les essais de combustion révèlent la présence d’odeurs et un dégagement de fumée pour les biocharbons de rapport 1,125. Ainsi, pour l’élaboration des biocharbons, les rapports 0,87 et 1 sous une pression de compactage de 500 kPa sont à retenir pour la formulation idéale.
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Haurissa, Jusuf, e Helen Riupassa. "Analisa Konveksi Paksa (Pemaksaan Udara Masuk) pada Proses Pembakaran Briket Ampas Sagu". Jurnal Rekayasa Mesin 11, n. 3 (15 dicembre 2020): 339–45. http://dx.doi.org/10.21776/ub.jrm.2020.011.03.5.
Abstract (sommario):
In previous studies, the initial process of burning briquettes still takes a long time, i.e. app 15-20 minutes. In normal briquette burning, a flame comes out from the briquette hole surface. The purpose of this research is to find a solution to accelerate the burning process and then the solution to use this process easily. The main objective of this research is to examine the amount of heat generated from the briquettes burning process with the number of holes as much as 10, 12, and 14, and to measure the time of initial briquette burning until the first time the flame came out on the briquettes surface. The basic ingredients of briquettes used in this study were sago waste. The tools used are a moisture meter to measure the water content, an infrared thermometer, a temperature measuring instrument, a Stopwatch to measure time, a digital anemometer to measure the airflow speed. From this study, the results obtained indicate that the combustion process in a forced air convection conditions, resulting in the rate of heat transfer as follows: a). For using the 10 holes briquettes, the heat transfer rate is about 8.51 watts, b). In the burning of 12 holes briquettes, the resulting heat transfer rate is about 16.57 watts, c). While on the 14 holes briquettes burning, the rate of heat transfer is about 20.43 watts. When heat energy is applied to boil 5 liters of water, with a 10-hole briquette, the water boils within 23.54 minutes. When using 12 holes briquettes, the water boils in 21.31 minutes, and in the use of 14 holes briquettes, the water boils in 20.21 minutes. It is concluded that the shortest time to boil 5 liters of water is when using briquettes with 14 holes, which boils in 23.34 minutes. These results indicate that forced convection can speed up the briquette burning process and produce a fairly high temperature.
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Luz, Leandro Domingos, e Mauro Parolin. "Caracterização dos Sedimentos Turfosos em Campo Mourão, Paraná, Brasil (Characterization of Peat Bogs in Campo Mourão, Paraná State, Brazil )". Revista Brasileira de Geografia Física 7, n. 2 (2 giugno 2014): 319–26. http://dx.doi.org/10.26848/rbgf.v7.2.p319-326.
Abstract (sommario):
Foi caracterizado os sedimentos turfosos da planície dos rios Água dos Papagaios e Ranchinho no município de Campo Mourão, PR. Para tanto, foram determinados: a) a datação absoluta (14C); b) a caracterização dos sedimentos via escala de von Post; c) o percentual de queima do material, sólido e volátil e d) a determinação granulométrica do sedimento. Os depósitos no rio Água dos Papagaios apresentaram idades entre ~7.280 anos cal AP. (75 cm) e ~3.280 anos cal AP. (45 cm), portanto formada durante o Holoceno. Por sua vez o depósito do rio Ranchinho apresentou idades mais antigas, de ~48.800±270 anos AP. (95 cm) e ~41.460 anos cal AP. (45 cm). Os depósitos apresentaram alto grau de decomposição entre as classes H6 e H9 (hêmica e sáprica). Os percentuais de combustão volátil e sólido foram maiores no testemunho rio Água dos Papagaios (29,89% e 45,06% respectivamente). No entanto, em virtude da presença de conteúdo mineralógico e dos valores médios de combustão o uso de ambas as turfeiras como combustível não é viável. A B S T R A C T Were characterized the peaty sediments of rivers Água dos Papagaios and Ranchinho floodplain in Campo Mourão, PR. Thus, we determined: a) the absolute dating (14C); b) the characterization of sediments with von Post scale; c) the percentage of the burning material, solid and volatile; d) sediments granulometry. The deposits ages in the river Água dos Papagaios were between ~ 7280 years cal BP. (75 cm) and ~ 3280 years cal BP. (45 cm) thus formed during the Holocene. Turn the deposit of the river Ranchinho presented higher age of ~ 48,800 ± 270 years BP. (95 cm), and ~ 41,460 years cal BP. (45 cm). The deposits showed a high degree of decomposition between classes H6 and H9. The percentage of volatile and solid combustion were higher in the Água dos Papagaios core (29.89% and 45.06 % respectively). However, due to the presence of mineral content and average values of the combustion use of both peats as fuel is not feasible. Key words: Peat, von Post scale, Pleistocene, Holocene.
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Benscoter, Brian W., e R. Kelman Wieder. "Variability in organic matter lost by combustion in a boreal bog during the 2001 Chisholm fire". Canadian Journal of Forest Research 33, n. 12 (1 dicembre 2003): 2509–13. http://dx.doi.org/10.1139/x03-162.
Abstract (sommario):
Fire directly releases carbon (C) to the atmosphere through combustion of biomass. An estimated 1470 ± 59 km2 of peatland burns annually in boreal, western Canada, releasing 4.7 ± 0.6 Tg C to the atmosphere via direct combustion. We quantified within-site variation in organic matter lost via combustion in a bog peatland in association with the 116 000-ha Chisholm, Alberta, fire in 2001. We hypothesized that for peatlands with considerable small-scale microtopography (bogs and treed fens), hummocks will burn less than hollows. We found that hollows exhibit more combustion than hummocks, releasing nearly twice as much C to the atmosphere. Our results suggest that spatial variability in species composition and site hydrology within a landform and across a landscape could contribute to considerable spatial variation in the amounts of C released via combustion during peatland fire, although the magnitude of this variation may be dependent on fire severity.
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Suluh, Sallolo, Dennis Lorenza, Rigel Sampelolo, GAN Pongdatu, Dina Ramba e Agus Widyianto. "Evaluation of a biomass combustion furnace using different kinds of combustion chamber casing materials". Eastern-European Journal of Enterprise Technologies 5, n. 8 (125) (31 ottobre 2023): 6–15. http://dx.doi.org/10.15587/1729-4061.2023.288834.
Abstract (sommario):
This research systematically evaluates a biomass combustion furnace, focusing on the influence of varying combustion chamber casing materials. The study employs controlled laboratory experiments to investigate the impact of different casing materials on combustion performance, thermal efficiency, and practical applications such as water boiling capacity. The research uses distinct materials, including clay, steel, and aluminum, for combustion chamber casings while maintaining consistent dimensions. The central experimental apparatus, an aluminum stove, was meticulously crafted, adhering to precise measurements. Coconut shell briquettes served as the primary fuel source for this investigation. The results reveal intriguing dynamics in combustion behavior. Notably, the choice of combustion chamber casing material significantly affects fire temperature, sleeve wall temperature, thermal efficiency, and the ability to boil water. Clay emerges as a standout performer, achieving high thermal efficiency (56.8 %), substantial water boiling capacity (25 liters), and efficient fuel consumption (1.28 kg of burnt briquettes). However, steel casing materials excel in generating the highest fire temperatures (up to 557 °C), underscoring their exceptional heat-conducting properties. Aluminum has fast temperature responses but may not retain heat like clay. The findings help optimize biomass combustion furnaces and associated applications. Material selection is crucial to attaining combustion goals like efficiency, temperature generation, or practical heat. These discoveries could lead to more efficient and ecologically friendly biomass combustion systems for sustainable energy and resource use
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Johnston, D. C., M. R. Turetsky, B. W. Benscoter e B. M. Wotton. "Fuel load, structure, and potential fire behaviour in black spruce bogs". Canadian Journal of Forest Research 45, n. 7 (luglio 2015): 888–99. http://dx.doi.org/10.1139/cjfr-2014-0334.
Abstract (sommario):
Boreal peatlands in Canada comprise a substantial store of soil organic carbon (peat), and this peat is vulnerable to extensive burning during periods of extended drying. Increased frequency of extreme weather events in boreal regions is expected with future climate change, and the conditions that would support sustained smouldering peat combustion within peatlands may be more common. Organic soils tend to burn by smouldering combustion, a very slow-moving process in fuels such as those found in peatlands. Thus the most extreme conditions for carbon loss to the atmosphere due to the burning of peat likely occur when widespread propagation of flaming combustion leads to widespread initiation of smouldering. To investigate the potential for large-scale, high-intensity fire spread across forested bogs, we examined the fuel conditions in forested bogs necessary to support active crown fire. We measured surface and canopy fine fuels (those available to contribute to the propagating energy flux of the main flaming front) across a postfire chronosequence of forested boreal bog from central Alberta, Canada. We found that fuel load of fine surface material remained relatively constant across the chronosequence and at levels large enough to support crown fire initiation. Black spruce (Picea mariana (Mill.) B.S.P.) regeneration begins to fill in the crown space with increasing time since disturbance and achieves crown bulk densities similar to black spruce upland forests. We estimated that after about 80 years, the black spruce canopy has developed enough available fuel to support active crown fire on between 10% to 40% of days in a typical fire season in central Alberta, Canada. Broad-scale propagation of high-intensity fire across a peatland when coincident with drought-induced lower moisture in deep peatland layers has the potential to lead to a substantial release of stored terrestrial carbon.
Tesi sul tema "Combustion du bois":
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Florea, Tudor. "Simulation numérique de la combustion du bois dans une chaudière automatique de 400 kW". Valenciennes, 2010. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/50dbded6-e6b8-4d98-be2c-f710442567f9.
Abstract (sommario):
Ce travail présente la mise en place, à l’aide de mesures expérimentales, d’un outil numérique qui décrit le mieux possible la combustion du bois dans une chaudière automatique à grille mobile de moyenne puissance. Deux types de mesure ont été réalisées : globales et locales. La première catégorie concerne les paramètres de fonctionnement de l’installation. Les mesures locales concernent les profils de température, de vitesse (diagnostique optique par laser) et de concentrations des gaz au sein du foyer. L’ensemble de ces mesures a permis de mettre en évidence les régimes de fonctionnement, la nature turbulente de l’écoulement et le caractère instationnaire des flammes. Ces mesures ont servi ensuite comme support pour l’analyse des calculs numériques. L’approche utilisée pour modéliser le foyer repose sur un couplage code de mécanique des fluides numérique - code 2D. L’étude numérique a été d’abord orientée vers la simulation de la combustion des matières volatiles au-dessus du lit de combustible, à l’aide du logiciel Fluent. . Une cinétique chimique semi-globale (6 réactions) a été employée dans un premier temps. Ces éléments ont permis d’évaluer l’impact de la distribution d’air secondaire. Ainsi, en passant d’une distribution asymétrique à symétrique, l’émission de CO peut être réduite par un facteur trois. Le calcul numérique est capable de reproduire les tendances observées expérimentalement, mais la cinétique semi-globale surestime le taux de CO. Suite à ces constats, un schéma réactionnel réduit (40 réactions) a été proposé. Celui-ci s’est montré beaucoup plus précis en ce qui concerne les teneurs en CO, O2 et CO2. Quant à l’écoulement, un bon accord entre les valeurs de vitesse expérimentales et numériques a été observé sur l’axe du foyer. Également, l’emplacement des zones de recirculation prédit par calcul correspond globalement à ce qui est indiqué par voie expérimentale. En complément, la cinétique à 40 réactions a été confrontée, en utilisant le code CHEMKIN II, aux résultats expérimentaux et au mécanisme réactionnel à 49 réactions (22 espèces) de Leroy et al. (2008) Le premier s’avère plus réactif que le dernier. Cependant, le schéma cinétique à 40 réactions se trouve dans un bon accord avec les données expérimentales à basse température (700 - 1000 K) et faible richesse (0,6 - 1)This work presents the implementation of a numerical tool, which can predict as best as possible the woodchips combustion within a medium power reciprocating grate boiler. In order to do so, several global and local measurements were conducted. The first category concerns the operating parameters of the installation. The local measurements concern the profiles of temperature, velocity and gas concentrations inside the furnace. The measurements allowed the ascertaining the operating regimes, the turbulent nature of the flow and the unsteadiness of the flames. Later, these measurements served to analyze the numerical simulations. The approach used for the furnace modelling is based on the computational fluid dynamics code - 2D code coupling. The numerical study was firstly oriented towards the volatiles combustion above the fuel bed, using the code Fluent. A semi-global reaction mechanism (6 reactions, 9 species) was first used. These elements allowed us to evaluate the impact of the secondary air distribution. Thus, the CO emission can be reduced by a factor of three when the secondary air configuration is changed from asymmetrical to symmetrical. The numerical computation is able to reproduce these tendencies, but the semi-global mechanism overestimates the CO concentration. Following these observations, a reduced mechanism (40 reactions, 17 species) was introduced, which proved to be much more accurate as far as the CO, O2 and CO2 are concerned. Regarding the flow analysis, a good agreement was found between the measured and computed velocities. In addition, the computed location of the recirculation zones corresponds globally with the experimental observations. Further, the 40 reactions mechanism was compared, using the CHEMKIN II code, to the experimental results and the 49 reactions (22 species) mechanism of Leroy et al. (2008). The first was found to be more reactive then the last one. However, the 40 reactions mechanism is in a good agreement with the experimental at low temperature (700 - 1000 K) and low fuel to air ratio (0. 6 - 1)
2
Flity, Hassan. "Modélisation de la dégradation et combustion du bois de construction". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0250.
Abstract (sommario):
L'utilisation du bois dans la construction présente de nombreux avantages, mais aussi des risques en termes de sécurité incendie. La littérature regorge d'études, qu'elles soient expérimentales ou numériques, sur le comportement au feu du bois. Cependant, les résultats, divers et variés, ne permettent pas d'identifier un comportement intrinsèque au bois, et le cadre réglementaire doit se résoudre à de nombreuses hypothèses simplificatrices. L'objectif de ce travail de thèse est d'étudier la dégradation thermique du bois à l'échelle du cône calorimètre. L'originalité de l'étude repose sur l'adoption d'une démarche à complexité croissante, l'utilisation d'une métrologie méticuleuse et sur une caractérisation la plus complète possible des propriétés des échantillons de bois étudiés. La dégradation implique de nombreux processus qui interagissent entre eux, tels que le séchage, la pyrolyse et la combustion avec ou sans flamme, entraînant des transferts de chaleur et de masse. Vu la complexité d'étudier tous ces phénomènes simultanément, la stratégie adoptée a consisté à séparer autant que faire se peut les différents phénomènes par le biais de modèles et d'expériences spécifiques. Pour s'affranchir du problème du séchage et des transferts hydriques, l'ensemble du travail a été réalisé sur du bois anhydre. Dans un premier temps, des méthodes de caractérisation spécifiques ont été utilisées afin de déterminer les propriétés thermiques du bois et du charbon. Ces expériences ont permis d'établir des lois de comportement pour certaines de ces propriétés, facilitant ainsi leur intégration dans un modèle. Ensuite, une campagne expérimentale a été réalisée sur le bois à l'échelle matière en utilisant des techniques telles que l'analyse thermogravimétrique et la calorimétrie différentielle de balayage, sous atmosphère inerte. À cette échelle, le bois est thermiquement mince, ce qui a permis de développer un modèle cinétique capable de prédire la perte en masse, la vitesse de perte en masse et la chaleur absorbée ou générée par le bois lors de la pyrolyse, en fonction de la température. Ensuite, une campagne expérimentale a été réalisée sur des échantillons de bois à l'échelle du cône calorimètre sous atmosphère inerte afin de valider le modèle de pyrolyse 3D développé pour la prédiction de la pyrolyse du bois, en l'absence de combustion, lorsque celle-ci est principalement pilotée par les transferts thermiques dans le matériau. Des essais sous air ont enfin été réalisés en vue d'une modélisation globale de la combustion du bois anhydre, nécessitant une caractérisation précise de la combustion du charbon et de l'apport de chaleur associé et du flux de chaleur apporté par la flammeThe use of wood in construction offers numerous advantages, but also poses fire safety risks. Several studies available in the literature, whether experimental or numerical, have investigated the fire behavior of wood. However, the diverse and varied results do not allow the identification of the intrinsic behavior of wood, and regulatory frameworks have to rely on numerous simplifying assumptions. The objective of this thesis is to study the thermal degradation of wood at the cone calorimeter scale. The uniqueness of the study lies in the adoption of an increasingly complex approach, the use of meticulous metrology, and the most comprehensive characterization of the properties of the wood samples under investigation. Degradation involves numerous interacting processes such as drying, pyrolysis, and combustion with or without flames, resulting in heat and mass transfer. Given the complexity of studying all these phenomena simultaneously, the strategy adopted was to separate the different phenomena as much as possible through models and specific experiments. In order to overcome the problem of drying and hydric transfer, all the work was carried out on dry wood. First, specific characterization methods were used to determine the thermal properties of wood and charcoal. These experiments helped to establish behavioral laws for some of these properties, facilitating their integration into a model. Subsequently, an experimental campaign was conducted at the material scale of wood using techniques such as thermogravimetric analysis and differential scanning calorimetry under an inert atmosphere. At this scale, wood is thermally thin, which allowed the development of a kinetic model capable of predicting mass loss, mass loss rate, and heat absorbed or generated by wood during pyrolysis as a function of temperature. Next, an experimental campaign was carried out on wood samples at the scale of the cone calorimeter in an inert atmosphere to validate the 3D pyrolysis model developed to predict wood pyrolysis in the absence of combustion, driven primarily by heat transfer within the material. Finally, tests in an air environment were conducted for a comprehensive modeling of dry wood combustion, which requires a precise characterization of char combustion, the associated heat generated, and the heat flux supplied by the flame
3
Bernard, Claude Zoulalian André. "Caractérisation et optimisation de la combustion de bois fragmenté en chaufferies automatiques". [S.l.] : [s.n.], 2005. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2005_0206_BERNARD.pdf.
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Haas, Frédéric. "Etude de la post-combustion des créosotes dans des appareils de chauffage au bois". Mulhouse, 1990. http://www.theses.fr/1990MULH0158.
Abstract (sommario):
Cette thèse portant sur l'étude de la réduction des émissions de polluants issus de la combustion du bois a pour cadre expérimental les normes américaines en vigueur dans ce domaine. Une étude complète de deux appareils de chauffage au bois a été menée pour situer leur taux d'émission. Une étude du catalyseur de post-combustion a été réalisée sur la base d'un appareil existant. A partir de cette étude, nous avons étudié une adaptation de ce système sur un foyer de cheminée. Comme alternative à ce procédé, nous avons mis au point une chambre de post-combustion utilisant de l'air secondaire surchauffé. Nous avons caractérisé les émissions de particules de ce système. Nous avons poursuivi cette étude par la réalisation d'un bilan énergétique complet d'un appareil de chauffage muni d'une chambre de post-combustion. Nous nous sommes également intéressés aux émissions issues de foyers ouverts et nous avons mis au point une chambre de post-combustion spécifique à cette catégorie d'appareils. Nous avons fini cette étude par la mise au point d'un système de détection d'hydrocarbures gazeux permettant le pilotage automatique de la post-combustion
5
Riviere, Gaëtan. "Conception d’un micro-cogénérateur aux granulés de bois". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0321/document.
Abstract (sommario):
Dans le cadre du projet ANR AGATCO (Advance GAz Turbine for COgeneration) qui a débuté fin 2012, la conception d’un micro-cogénérateur aux granulés de bois permettant de produire 1,5 kW électrique et 10 kW thermique a été entrepris et est présentée dans ce manuscrit. Basé sur la technologie d’une turbine à air chaud à combustion externe, ce micro-cogénérateur utilise la combustion des granulés couplés à un échangeur de chaleur et une micro-turbine. La technologie demande la conception d’un nouveau foyer (brûleur et chambre de combustion) adapté pour la production de fumées à haute température (1200°C). Le défi est grand car le débit de fumées souhaité est important (27g/s) et la puissance de combustible est faible (15kW). Deux solutions sont proposées pour répondre à la problématique, la première utilise de l’air frais à température ambiante et la deuxième utilise le recyclage des fumées chaudes. La haute température des fumées permet d’obtenir une température d’entrée turbine de 1100°C après le transfert de chaleur dans l’échangeur. La caractérisation expérimentale et par simulation numérique de l’échangeur permet de vérifier ses performances. La micro-turbine utilise une technologie nouvelle de canaux hélicoïdaux à la place d’aubes qui lui permettent d’avoir des dimensions faibles pour les performances souhaitées. Les travaux effectués ont permis de mettre en valeur plusieurs résultats : la réalisation de la combustion haute température dans des conditions fortement défavorables, les performances très intéressantes de l’échangeur de chaleur tous en proposant des améliorations pour optimiser les échanges et les améliorations à apporter à la turbineAs part of the AGATCO ANR project (Turbine Advance GAz for cogeneration), which began at the end of 2012, the design of a micro-cogeneration generating 1.5 kW of electricity and 10 kW of heat was started and presented in this manuscript. Based on the technology of an externally fired gas turbine, this micro-CHP uses the combustion of pellets coupled to a heat exchanger and a micro-turbine. This technology requires the design of a new fireplace (burner and combustion chamber) suitable to produce fumes at high temperatures (1200°C). The challenge is significant because the desired smoke flow is important (27 g/s) and the fuel power is low (15 kW). Two solutions are proposed to solve the problem, the first uses fresh air at ambient temperature and the second uses recycled hot fumes. The high temperature of the fumes makes it possible to obtain a turbine inlet temperature of 1100°C after the transfer of heat into the exchanger. Experimental and numerical simulation characterization of the exchanger makes it possible to verify its performances. The micro-turbine uses a new technology using channel instead of blades allowing it to have small dimensions for the desired performance. The work carried out made it possible to highlight several results: the realization of the high temperature combustion in very unfavorable conditions, the very interesting performances of the heat exchanger while proposing improvements to optimize the exchanges and the improvements to be brought to the turbine
6
Bernard, Claude. "Caractérisation et optimisation de la combustion de bois fragmenté en chaufferies automatiques". Nancy 1, 2005. http://docnum.univ-lorraine.fr/public/SCD_T_2005_0206_BERNARD.pdf.
Abstract (sommario):
Les chaufferies automatiques au bois fragmenté connaissent un fort développement. Ces chaufferies doivent répondre aux besoins en chaleur et sont soumises aux aléas du bois. La chaudière doit adapter sa puissance, et permettre l'utilisation de bois dont la granulométrie et l'humidité peuvent fluctuer. Notre étude est menée sur une chaudière automatique à grilles mobiles de 200 kW. 1000 heures d'essais de combustion de sciures et de plaquettes, d'humidités variables selon 3 paliers de puissance permettent d'obtenir une représentation du CO émis par la combustion en fonction de l'humidité, de la puissance et du débit d'air. Ce modèle permet d'évaluer l'impact environnemental de différents types de régulations de combustion. Une nouvelle logique de régulation a alors pu être proposée : elle permet de réduire jusqu'à 40% les émissions de CO par une simple reprogrammation de l'automate et fonctionne quelles que soient les caractéristiques du bois ou la puissance appeléeThe development of automatic fed boilers using broken wood follows an upward trend nowadays. These boilers have to fulfil the heating needs despite the heterogeneity of wood. The boiler has to fit its power and allow the use of wood which size and humidity may fluctuate. Our study uses an automatic fed boiler with moving grates of 200 kW. 1000 hours of combustion experiments with sawdust and chips, with different moistures varying according to 3 stages of power enable to achieve a representation of CO emitted from combustion depending on the humidity, the power and the air flow. This model allows to assess the environmental impact of different types of combustion regulations. A new logic of regulation has been then proposed : it enables to reduce up to 40% of the total CO emissions by a simple re-programming of the automaton and works whatever the wood characteristics or the demanded power
7
Rabot-Querci, Marie-Laure. "Etude d'un dispositif de traitement des imbrûlés des appareils de chauffage indépendants au bois". Nancy 1, 2006. http://docnum.univ-lorraine.fr/public/SCD_T_2006_0119_RABOT-QUERCI.pdf.
Abstract (sommario):
La principale pollution des appareils domestiques de chauffage au bois est liée aux émissions d'imbrûlés gazeux et solides dans les fumées. Pour réduire ces rejets, nous proposons l'utilisation d'un dispositif de traitement des fumées pour piéger les particules et les détruire par micro-ondes. Après une étude des émissions de différents foyers fermés et une caractérisation des particules issues de la combustion du bois, le travail réalisé sur le piégeage dans un lit filtrant de billes de ciment réfractaire a permis de piéger 50 % des particules avec un lit de 5 cm. Ce lit chargé de particules est ensuite chauffé par micro-ondes : une énergie de l'ordre de 200 kJ a permis de régénérer le filtre totalement. Cette étude a montré que la post-combustion de fumées par apport d'énergie micro-ondes est particulièrement adaptée aux particules issues de la combustion du bois, comparé à la régénération par apport d'énergie classique, et un cahier des charges complet du dispositif a été élaboréThe main source of pollution from residential wood stoves is due to unburned gas and solid phase compounds in the fumes. In order to reduce these pollutants, we propose to use an exhaust gas-treating device to trap the particles in the chimney and to expose them to microwave to break them down. We first evaluated the emissions and the particulate matter (PM) characteristics from different fireboxes. Then we studied separately each function of the system : we trapped 50 % of PM with a 5 cm layer of refractory cement marbles placed in the chimney and then we heated the filter with microwave. About 200 kJ allowed us to clean completely the filter. This study showed that a microwave post-combustion system is particularly well adapted to particulate matter issued from wood combustion, in comparaison with other sources of energy regeneration. We also described the complete specifications of our device
8
Pelletier, Chloé. "Analyse environnementale et économique des filières bois-énergie". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0331/document.
Abstract (sommario):
Le but de cette thèse est de conduire l’analyse environnementale et économique de plusieurs filières bois-énergie basée sur des technologies de combustion variées. Les bilans matière et énergie des filières s’appuient sur des modèles de croissance de la forêt, et sur des modèles de combustion basés sur les émissions de poêles et chaudières en conditions réelles. La croissance de la forêt est simulée pour le pin des Landes et le hêtre de Lorraine selon plusieurs itinéraires de gestion sylvicole. Les étapes de récolte, transformation, et transport, ainsi que les données économiques sont basées sur des données de la littérature L’analyse environnementale compare les impacts calculés selon deux méthodes : ReCiPe et CML 2001. Une analyse dynamique de l’impact « Changement Climatique » complète la discussion sur les impacts environnementaux du bois-énergie. Enfin, une perspective plus large est ouverte avec une modélisation de l’usage des terres et des coûts de production de biomasse-énergie à l’échelle globale. Les résultats de l’Analyse de Cycle de Vie montrent l’importance à la fois de la qualité de la combustion (et donc de la technologie) et des étapes de transformation et de transport de la biomasse. Par exemple, les poêles et chaudières à granulés bénéficient de très bons rendements énergétiques mais sont handicapés par l’étape de séchage de la biomasse, qui consomme des énergies fossiles. Ces équipements sont également beaucoup plus onéreux à installer que les poêles et chaudières à bûches. L’analyse dynamique montre que l’intensification des itinéraires forestiers par raccourcissement des cycles de croissance entraîne un impact supplémentaire qui n’est pas tout à fait compensé par l’augmentation de production des plantationsThe objective of this thesis is to conduct the environmental and economic analysis of several wood-to-energy production chains based on various wood combustion technologies. The material and energy balances of the production chains are determined with modeling of forest growth and of wood combustion. The wood combustion models use the emission factors from real-scale experimental tests on stoves and boilers. Forest growth is modeled for maritime pine and beech plantations, according to several forest management schemes. The data on the harvest, transformation, and transport steps, as well as the economic data, were taken from the literature. The environmental analysis compares the impacts calculated by two methods: ReCiPe and CML 2001. A dynamic analysis of the “climate change” impact complements the discussion on the environmental impacts of energy wood. Finally, we open a broader perspective with modeling of land use and production costs of bioenergy on a global scale. The results of the Life Cycle Analysis show the importance of both combustion quality (linked to combustion technology), and the transformation and transport steps. For instance, pellet stoves and boilers have excellent efficiencies, but suffer from the consumption of fossil fuels to dry the biomass. These technologies are also much more expensive to buy than log stoves or boilers. The dynamic analysis shows that the intensification of wood production via the shortening of growth cycles leads to higher impacts that are not completely offset by the higher production rate
9
François, Jessica. "Modélisation et évaluation environnementale des filières de cogénération par combustion et gazéification du bois". Thesis, Université de Lorraine, 2014. http://www.theses.fr/2014LORR0071/document.
Abstract (sommario):
Le développement du bois énergie est un des principaux leviers dans la lutte contre le changement climatique. Cependant son utilisation à grande échelle n’est pas sans risque pour l’environnement. Afin de quantifier les impacts environnementaux de la filière bois énergie, nous avons, dans un premier temps, développé un modèle systémique de la filière, depuis la forêt jusqu’à la production d’énergie. Deux technologies ont été considérées pour la co-production d’électricité et de chaleur à partir de biomasse forestière : l’une, traditionnelle, par combustion directe, et l’autre, plus avancée mais moins mature, par gazéification. Dans le cas de la gazéification, nous avons défini les conditions opératoires les plus favorables du procédé en tenant compte des rendements énergétiques et exergétiques ainsi que de la qualité du syngas. Dans un deuxième temps, nous avons calculé les flux de carbone et de minéraux exportés lors de la récolte du bois ainsi que le nombre d’hectares requis, puis les ressources et rejets liées au fonctionnement des centrales biomasses. Nous avons noté qu’une intensification des pratiques sylvicoles résultait en une augmentation des exportations de minéraux. Enfin, nous avons évalué les performances environnementales des deux filières à l’aide d’une Analyse de Cycle de Vie (ACV). Dans le contexte énergétique français, les deux systèmes offrent des performances très similaires, avec un léger avantage à la combustion. Du point de vue du changement climatique, il serait plus particulièrement bénéfique de développer ces procédés biomasse afin de remplacer les technologies de production d’énergie basées sur les combustibles fossilesBiomass is one of the most promising renewable energy source in Europe. Its use as a substitute to fossil energy is expected to mitigate climate change. However, potential drawbacks are also feared with large scale development. In order to assess the environmental impacts of the biomass-to-energy chain, we firstly developed a model of the bioenergy system, from the forest to the energy production. We focused on two biomass power plants for combined heat and power (CHP) production: one is based on the conventional direct combustion process while the other is based on the more advanced gasification process. Gasification offers higher electrical efficiency, but its development is still facing technical difficulties. In case of the gasification process, we defined the best operating conditions regarding energetic and exergetic efficiencies, as well as the syngas quality requirements. Secondly, we calculated the carbon and mineral flows taken from the forest through energy wood harvesting, along with the forested area required to feed the CHP plant. The other resources and emissions related to the plant operation were also predicted. We observed that more extensive forestry practices led to an increase in the mineral exports. Finally, we evaluated the environmental performance of the two biomass CHP plants using life cycle assessment (LCA). Within French energy context, we found that both CHP technologies had very similar impacts with a slight advantage toward the combustion process. It appears of particular benefit to replace current fossil energy systems with biomass CHP plants to reduce climate change
10
François, Jessica. "Modélisation et évaluation environnementale des filières de cogénération par combustion et gazéification du bois". Electronic Thesis or Diss., Université de Lorraine, 2014. http://www.theses.fr/2014LORR0071.
Abstract (sommario):
Le développement du bois énergie est un des principaux leviers dans la lutte contre le changement climatique. Cependant son utilisation à grande échelle n’est pas sans risque pour l’environnement. Afin de quantifier les impacts environnementaux de la filière bois énergie, nous avons, dans un premier temps, développé un modèle systémique de la filière, depuis la forêt jusqu’à la production d’énergie. Deux technologies ont été considérées pour la co-production d’électricité et de chaleur à partir de biomasse forestière : l’une, traditionnelle, par combustion directe, et l’autre, plus avancée mais moins mature, par gazéification. Dans le cas de la gazéification, nous avons défini les conditions opératoires les plus favorables du procédé en tenant compte des rendements énergétiques et exergétiques ainsi que de la qualité du syngas. Dans un deuxième temps, nous avons calculé les flux de carbone et de minéraux exportés lors de la récolte du bois ainsi que le nombre d’hectares requis, puis les ressources et rejets liées au fonctionnement des centrales biomasses. Nous avons noté qu’une intensification des pratiques sylvicoles résultait en une augmentation des exportations de minéraux. Enfin, nous avons évalué les performances environnementales des deux filières à l’aide d’une Analyse de Cycle de Vie (ACV). Dans le contexte énergétique français, les deux systèmes offrent des performances très similaires, avec un léger avantage à la combustion. Du point de vue du changement climatique, il serait plus particulièrement bénéfique de développer ces procédés biomasse afin de remplacer les technologies de production d’énergie basées sur les combustibles fossilesBiomass is one of the most promising renewable energy source in Europe. Its use as a substitute to fossil energy is expected to mitigate climate change. However, potential drawbacks are also feared with large scale development. In order to assess the environmental impacts of the biomass-to-energy chain, we firstly developed a model of the bioenergy system, from the forest to the energy production. We focused on two biomass power plants for combined heat and power (CHP) production: one is based on the conventional direct combustion process while the other is based on the more advanced gasification process. Gasification offers higher electrical efficiency, but its development is still facing technical difficulties. In case of the gasification process, we defined the best operating conditions regarding energetic and exergetic efficiencies, as well as the syngas quality requirements. Secondly, we calculated the carbon and mineral flows taken from the forest through energy wood harvesting, along with the forested area required to feed the CHP plant. The other resources and emissions related to the plant operation were also predicted. We observed that more extensive forestry practices led to an increase in the mineral exports. Finally, we evaluated the environmental performance of the two biomass CHP plants using life cycle assessment (LCA). Within French energy context, we found that both CHP technologies had very similar impacts with a slight advantage toward the combustion process. It appears of particular benefit to replace current fossil energy systems with biomass CHP plants to reduce climate change
Libri sul tema "Combustion du bois":
1
1957-, Lévesque Benoît, e Canada Mortgage and Housing Corporation., a cura di. Appareils de combustion de bois et qualité de l'air intérieur. [Ottawa]: SCHL, 1997.
2
Ross, Highsmith V., e United States. Environmental Protection Agency, a cura di. Characterization of the wintertime Boise, Idaho, air shed: A comprehensive field study report for the U.S. EPA Office of Air Quality Planning and Standards. [Washington, D.C: U.S. Environmental Protection Agency, 1992.
3
The Tenth Biennial Bioenergy Conference (Boise, Id.). Bioenergy 2002 abstracts: Bioenergy for the environment: proceedings, September 22-26, 2002, Boise, Idaho. [Boise, Id.]: U.S. Dept. of Energy, 2002.
4
Code de bonnes pratiques pour l’utilisation du bois de chauffage et les petites installations de combustion. United Nations, 2022. http://dx.doi.org/10.18356/9789210057509.
Capitoli di libri sul tema "Combustion du bois":
1
Bandazheuski, Yuri, e Nataliia Dubovaya. "ELEMENTS OF ETIO-PATHOGENESIS OF HYPERHOMOCYSTEINEMIA IN CHILDREN LIVING IN THE REGIONS AFFECTED FROM THE ACCIDENT AT THE CHERNOBYL NUCLEAR POWER PLANT". In The scientific paradigm in the context of technological development and social change. Publishing House “Baltija Publishing”, 2023. http://dx.doi.org/10.30525/978-9934-26-297-5-25.
Abstract (sommario):
The prevalence of hyperhomocysteinemia in the population of children living in the area affected by the accident at the Chernobyl Nuclear Power Plant (ChNPP) requires a deep study of the etio-pathogenesis of metabolic disorders of the sulfur-containing amino acids methionine (Met) and homocysteine (Hcy) under radiation exposure. The purpose of the study was to assess the involvement of genetic (folate cycle polymorphisms – FC) and environmental factors in the occurrence of hyperhomocysteinemia in boys and girls living in the Ivankovsky and Polessky districts of the Kyiv region of Ukraine, near the Chernobyl Exclusion Zone (ChEZ). The methodology of the study is based on the evaluation by statistical methods of the results of genetic and laboratory examinations of 690 children (368 girls and 322 boys), aged 8-17 years, obtained in the course of projects of the European Commission, the Regional Council of Rhone-Alpes (France) and the French public organization "Children Chernobyl". It has been shown that in most cases, the violation of Hcy metabolism and the occurrence of hyperhomocystinemia in children from areas affected by the Chernobyl accident are caused by the association of genotypes with risk alleles of MTHFR:C677T and MTRR:A66G polymorphisms. Given the wide prevalence in the population, combinations of their heterozygous forms are of the greatest importance.The risk allele G of the MTRR:66 polymorphism also has a negative effect on the processes of Hcy methylation when associated with the risk allele G of the MTR:A2756G polymorphism and with compound heterozygosity A/CMTHFR:1298 – C/TMTHFR:677. In the body of boys, compared with the body of girls, combinations of risk alleles for FC polymorphisms are manifested by a more pronounced disturbance of Hcy metabolism. The A/AMTRR:66 genotype promotes Hcy utilization in the transsulfuration cycle, even if only one C allele of the MTHFR:677 polymorphism functions.An external environmental factor in the form of radioactive agents incorporated into vital organs, undermining cellular energy, has a negative impact on the processes of cobalamin methylation. The consequence of this is the occurrence of a state of hyperhomocysteinemia in more than 50 % of boys and girls who do not have risk alleles of MTR:A2756G, MTHFR:C677T and MTRR:A66G polymorphisms in the genome. Conclusions. The main internal cause of hyperhomocysteinemia in children living near the ChEZ is the association of risk alleles for FC genetic polymorphisms.The combined effect of endogenous (genetic mutations of FC) and exogenous (radioactive elements, their decay products, substances formed during the combustion of wood) factors leads to disruption of the Hcymethylation process and the emergence of a state of hyperhomocysteinemia in children living in the territory affected by the Chernobyl accident. This type of metabolic disorder can be considered a distant consequence of the Chernobyl accident. Further research should be aimed at developing measures for the prevention and treatment of hyperhomocysteinemia, as a condition associated with the occurrence of serious pathological processes.
2
McElroy, Michael B. "Natural Gas : The Least Polluting Of The Fossil Fuels". In Energy and Climate. Oxford University Press, 2016. http://dx.doi.org/10.1093/oso/9780190490331.003.0012.
Abstract (sommario):
In terms of emissions from combustion, natural gas, composed mainly of methane (CH4), is the least polluting of the fossil fuels. Per unit of energy produced, CO2 emissions from natural gas are 45.7% lower than those from coal (lignite), 27.5% lower than from diesel, and 25.6% lower than from gasoline. As discussed by Olah et al. (2006), humans have long been aware of the properties of natural gas. Gas leaking out of the ground would frequently catch fire, ignited, for example, by lightning. A leak and a subsequent fire on Mount Parnassus in Greece more than 3,000 years ago prompted the Ancient Greeks to attach mystical properties to the phenomenon— a flame than could burn for a long time without need for an external supply of fuel. They identified the location of this gas leak with the center of the Earth and Universe and built a temple to Apollo to celebrate its unique properties. The temple subsequently became the home for the Oracle of Delphi, celebrated for the prophecies inspired by the temple’s perpetual flame. The first recorded productive use of natural gas was in China, dated at approximately 500 BC. A primitive pipeline constructed using stems of bamboo was deployed to trans¬port gas from its source to a site where it could be used to boil brine to produce both economically valuable salt and potable water. Almost 2,000 years would elapse before natural gas would be tapped for productive use in the West. Gas from a well drilled near Fredonia, New York, was used to provide an energy source for street lighting in 1821. The Fredonia Gas Light Company, formed in 1858, was the first commercial entity established specifically to market natural gas. Joseph Newton Pew, founder of the Sun Oil Company (now Sunoco), established a company in 1883 to deliver natural gas to Pittsburgh, where it was used as a substitute for manufactured coal gas (known also as town gas). Pew later sold his interests in natural gas to J. D. Rockefeller’s Standard Oil. The early application of natural gas was primarily for lighting, not only for streets but also for factories and homes.
3
"minutes retention depending on the oil processed. Then, Synthetic silica hydrogels: Described in the immediately the oil is heated to 70°C, (158°F) to assist "breaking" the preceding section. emulsion and the mixture is passed through a primary (first) centrifuge. The general dosage of acid-activated bleaching earths is 0.3-0.6%, depending on the quality of the oil and bleach-In contrast, the short-mix process, developed in Europe, ing earth. Bleaching earths provide catalytic sites for de-is conducted at 90°C (84°F), uses a more highly concen-composition of oxidation products. Peroxide values (mea-trated caustic, and a mixing time and primary centrifuging sure of aldehydes) and p-anisidine values (precursors for time of less than 1 minute [135]. Less heat damage to the oxidative degradation) first rise and then decrease during oil and higher refining yield are claimed by advocates of bleaching. Bleaching processes used include atmospheric the long mix process. batch, vacuum batch, and continuous vacuum. Vacuum 4. Silica Absorption bleaching has the advantage of excluding air, partially by In traditional refining, oil from the primary centrifuge is vaporization of water in the earth, and is recommended. A washed with warm soft water to remove residual soap and typical vacuum bleaching process is 20-30 minimum at passed through a (secondary) centrifuge. The washed oil 100-110°C (212-230°F) and 50 mmHg absolute [135]. then is dried under vacuum. However, disposal of wash The reactions catalyzed during bleaching continue into water is increasingly becoming a problem, and the indus-the filter bed and are known as the "press bleaching ef-try is shifting to a modified caustic "waterless" refining fect." The reactive components of oil remain in the bleach-process. Soaps poison the adsorption sites of clays in later ing bed. Care should be taken to "blow" the filter press as bleaching operations and are removed by silica hydrogels. free of oil as possible and to wet the filter cake (which can The oil may be degummed with use of chelating acids, be very dusty) to prevent spontaneous combustion [137]. caustic neutralized, passed through a primary centrifuge, At this point, the product is RB ("refined, bleached") and may be partially vacuum-dried. Synthetic silica hy-oil. If the intended product is an oil, it can be sent to the de-drogels, effective in removing 7-25 times more phos-odorizer and become RBD. If solids are desired, the solids-phatides and soaps than clay on a solids basis, and for re-temperature profile of the oil may be modified by hydro-moving phosphorus and the major metal ions, is added genation, interesterification, or chill fractionation, alone or and mixed with the oil. By absorbing these contaminants in combination. first, the bleaching clay is spared for adsorbing chloro-6. Hydrogenation phyll and the oxidation-degradation products of oil Hydrogenation is the process of adding hydrogen to satu-[136-138]. rate carbon-to-carbon double bonds. It is used to raise try-5. Bleaching glyceride melting points and to increase stability as by jective of bleaching is to remove various contami-converting linolenic acid to linoleic in soybean oil [141]. A The ob lighter, "brush" hydrogenation is used for the latter pur-nants, pigments, metals, and oxidation products before the pose. oil is sent to the deodorizer. Removal of sulfur is especial-Most of the catalysts that assist hydrogenation are nick-ly important before hydrogenation of canola and rapeseed el-based, but a variety is available for special applications. oils. Flavor of the oil also is improved. As mentioned in the "Selectivity" refers to ability of the catalyst and process to preceding section, silica hydrogels will adsorb many of sequentially saturate fatty acids on the triglycerides in the these contaminants and spare the bleaching earth. Howev-order of most unsaturated to the fully saturated. For row er, earths are still used for these purposes in installations crop oils, perfect selectivity would be: that have not adopted hydrated silicas. Types of bleaching materials available include [136,139,140]: C18:3 C18:2 C18:1 Linolenic acid Linoleic acid Oleic acid Neutral earths: Basically hydrated aluminum silicates, sometimes called "natural clays" or "earths," and C18:0 fuller's earth, which vary in ability to absorb pigments. Stearic acid Acid-activated earths: Bentonites or montmorillonites, Although typical hydrogenation is not selective, it can be treated with hydrochloric or sulfuric acid to improve favored to a limited degree by selection of catalyst and by their absorption of pigments and other undesirable temperature and pressure of the process. Efficient hydro-components, are most commonly used. genation requires the cleanest possible feed stock (without Activated carbon: Expensive, more difficult to use, but of soaps, phosphatides, sulfur compounds, carbon monoxide, special interest for adsorbing polyaromatic hydrocar-nitrogen compounds, or oxygen-containing compounds) bons from coconut and fish oils. and the purest, driest hydrogen gas possible [140]." In Handbook of Cereal Science and Technology, Revised and Expanded, 361–73. CRC Press, 2000. http://dx.doi.org/10.1201/9781420027228-35.
Atti di convegni sul tema "Combustion du bois":
1
Jha, Saroj Kumar, Sundar Rajan Krishnan e Kalyan Kumar Srinivasan. "Quasi-Two-Zone Modeling of Diesel Ignition Delay in Pilot-Ignited Partially Premixed Low Temperature Natural Gas Combustion". In ASME 2010 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/icef2010-35127.
Abstract (sommario):
This paper presents simulated ignition delay (ID) results for diesel ignition in a pilot-ignited partially premixed, low temperature natural gas (NG) combustion engine. Lean premixed low temperature NG combustion was achieved using small pilot diesel sprays (2–3% of total fuel energy) injected over a range of injection timings (BOIs ∼ 20°–60° BTDC). Modeling IDs at advanced BOIs (50°–60° BTDC) presented unique challenges. In this study a single-component droplet evaporation model was used in conjunction with a modified version of the Shell autoignition (SAI) model to obtain ID predictions of pilot diesel over the range of BOIs (20°-60° BTDC). A detailed uncertainty analysis of several model parameters revealed that Aq and Eq, which affect chain initiation reactions, were the most important parameters (among a few others) for predicting IDs at very lean equivalence ratios. The ID model was validated (within ± 10 percent error) against experimentally measured IDs from a single-cylinder engine at 1700 rpm, BMEP = 6 bar, and intake manifold temperature (Tin) of 75°C. For BOIs close to TDC (e.g., 20° BTDC), the contribution of diesel evaporation times (Δθevap) and droplet diameters to predicted IDs were more significant compared to advanced BOIs (e.g., 60° BTDC). Increasing Tin (the most sensitive experimental input variable affecting predicted IDs), led to a reduction in both the physical and chemical components of ID. Hot EGR led to shorter predicted and measured IDs over the range of BOIs, except 20° BTDC. In general, the thermal effects of hot EGR were found to be more pronounced than either dilution or chemical effects for most BOIs. Finally, uncertainty analysis results also indicated that ID predictions were most sensitive to model parameters AP3, Aq, and Af1, and Eq, which affected chain initiation and propagation reactions and also contributed the most to overall uncertainties in IDs.
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Iwasaki, Hideyuki, Yuuto Higasa, Masaaki Takiguchi, Seiichi Sue e Keitaro Shishido. "Effects of Design for Piston Pin and Bearing on State of Bearing Lubrication". In ASME 2007 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/icef2007-1723.
Abstract (sommario):
We measured the friction of piston pin boss bearings for a gasoline engine to make sure of the state of lubrication. In addition, we checked how the shape of the piston pin as well as that of the pin boss influenced the state of bearing lubrication, which was analyzed according to the FEM calculations of pin and bearing contact pressure. As a result, it was made clear that the state of bearing lubrication sharply deteriorated at an engine speed of 3500 rpm or higher because the deformed pin caused the pin edge to heavily come into contact with the bearing, and a side relief was able to improve the state of lubrication at a high engine speed. We also gave a check to the piston pin for thickness to see how it influenced the state of lubrication, finding that a lighter-weight pin led to the deterioration of lubrication.
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Langella, Ivan, Johannes Heinze, Thomas Behrendt, Lena Voigt, Nedunchezhian Swaminathan e Marco Zedda. "Turbulent Flame Shape Switching at Conditions Relevant for Gas Turbines". In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91879.
Abstract (sommario):
Abstract A numerical investigation is conducted in this work to shed light on the reasons leading to different flame configurations in gas turbine combustion chambers of aeronautical interest. Large eddy simulations (LES) with a flamelet-based combustion closure are employed for this purpose to simulate the DLR-AT Big Optical Single Sector (BOSS) rig fitted with a Rolls-Royce developmental lean burn injector. The reacting flow field downstream this injector is sensitive to the intricate turbulent-combustion interaction and exhibits two different configurations: (i) a penetrating central jet leading to an M-shape lifted flame; or (ii) a diverging jet leading to a V-shaped flame. First, the LES results are validated using available BOSS rig measurements, and comparisons show that the numerical approach used is consistent and works well. The turbulent-combustion interaction model terms and parameters are then varied systematically to assess the flame behavior. The influences observed are discussed in the paper from physical and modelling perspectives to develop physical understanding on the flame behavior in practical combustors for both scientific and design purposes.
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Weilenmann, Markus, Yuan Xiong, Mirko Bothien e Nicolas Noiray. "Background Oriented Schlieren of Fuel Jet Flapping Under Thermoacoustic Oscillations in a Sequential Combustor". In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75517.
Abstract (sommario):
This study deals with thermoacoustic instabilities in a generic sequential combustor. The thermoacoustic feedback involves two flames: the perfectly premixed swirled flame anchored in the first stage and the sequential flame established downstream of the mixing section, into which secondary fuel is injected in the vitiated stream from the first stage. It is shown that the large amplitude flapping of the secondary fuel jet in the mixing section plays a key role in the thermoacoustic feedback. This evidence is brought using high-speed Background Oriented Schlieren (BOS). The fuel jet flapping is induced by the intense acoustic field at the fuel injection point. It has two consequences: first, it leads to the advection of equivalence ratio oscillations toward the sequential flame; second, it modulates the residence time of the ignitable mixture in the mixing section, which periodically triggers autoignition kernels developing upstream of the chamber. In addition, the BOS images are processed to quantify the flow velocity in the mixing section and these results are validated using PIV. This study presents a new type of thermoacoustic feedback mechanism which is peculiar to sequential combustion systems. In addition, it demonstrates how BOS can effectively complement other diagnostic techniques that are routinely used for the study of thermoacoustic instabilities.
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Kokko, Ari, e Stig Nickull. "The First Operational Experience of World’s Largest Biofuel Fired CFB". In 17th International Conference on Fluidized Bed Combustion. ASMEDC, 2003. http://dx.doi.org/10.1115/fbc2003-034.
Abstract (sommario):
Oy Alholmens Kraft Ab, with its unique combination of owners, was founded for the purpose of building a power station at Pietarsaari on the west coast of Finland. The power utility companies initiated the co-operation with the saw-, pulp and paper mill owners with the goal of finding a solution which maximized biomass utilization through co-firing with other fuels, to produce steam and heat in a utility sized power plant. Concept development resulted in a 240 MWe circulating fluidized bed unit with a flexible and demanding combination of fuels. The Alholmens Kraft power plant supplies process steam to the nearby UPM-Kymmene paper mill, and for district heating in Pietarsaari. The plant produces electricity for the power company owners in Finland and in Sweden. The CFB boiler steam capacity is 550 MWth (1875 MMBtu/hr), giving a maximum electric power of 240 MWe. When commissioned in autumn 2001 the boiler was one of the largest CFB boilers in the world, and the largest biofuel-burning CFB. The Alholmens Kraft CFB boiler is a multi-fuel boiler, whose main fuels are bark, wood residue and peat, with coal as a back-up fuel. Due to its location at the pulp and paper mill, high reliability and low emissions were the most important design criteria for the boiler. Steam production for the mill must be ensured all year-round, apart from during the mill’s short annual service shutdowns. Another important design consideration was the controllability of the boiler due to Nord Pool electricity production requirements. Typical regular load variation is between day and night but sometimes the load change speed requirement is quite high. This paper presents the Alholmens Kraft power plant application, and its very smooth start-up and operational experience during the first year with different fuels and fuel combinations at various load levels. The paper also describes how well the large boiler has performed with regard to the strict emission limits. The selection of design fuel contributes well towards the target for net CO2 reduction, but it also places huge requirements in terms of fuel purchasing and logistics. The volumetric fuel consumption by the boiler at full load is 1000 m3/h (35 000 ft3) of biofuel. More coal, the support and reserve fuel, is used in spring as weather conditions may cause availability problems with peat, before the new peat can be harvested and dried at the peat bogs. Coal is always available at the site. This paper presents the first year’s operational experience of the fuel logistics chain. The successful Alholmens Kraft CFB boiler project is an excellent example of the very wide fuel flexibility that is possible in a CFB unit.
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von der Haar, Henrik, Ulrich Hartmann, Christoph Hennecke, Friedrich Dinkelacker e Joerg R. Seume. "Defect Detection in an Annular Swirl-Burner-Array by Optical Measuring Exhaust Gases". In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57847.
Abstract (sommario):
Defects in combustion chambers of aircraft engines might have an impact on the reliability of the downstream turbine and the machine’s performance. Detecting failures in the combustion chamber of an aircraft engine during operation may improve the resource management and the availability of the system. Aim of the ongoing research project is to find an approach to evaluate the state of the jet engine by analyzing the temperature and emissions field in the exhaust jet. This investigation is part of the collaborative research center SFB 871. The SFB 871 deals with the improvement of the regeneration process of complex capital goods such as aircraft engines. Maintenance, repair, and overhaul processes would be more efficient if the internal status of the engine would be known while still on the wing before it is disassembled. The feasibility of this approach is investigated for a pilot scaled model combustor, which provides optical access and allows the selection of “defined errors” in the combustor. It consists of an atmospheric tubular combustor with an array of eight premixed swirl burners with a maximum output of 160 kW. The operating conditions of one of the eight burners concerning power and air-fuel ratio, can be controlled. A power distribution between the burners is typical fault in an aircraft combustor and will be investigated in this study. It is observed that it is possible to determine small deviations by measuring density profiles applying a tomographic background-oriented schlieren (BOS) technique behind the combustor. Additionally, particle image velocimetry is used to measure differences in the velocity field of the exhaust gases. This study shows that a minimum power deviation of one burner in an array of a total of eight burners is detectable in the exhaust plane with the above mentioned measurement techniques.
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de Toledo Cullen, Joãb Amos, Durval Duarte Júnior e José Manoel Martins Leites. "Stress Analysis on the PistonPin Boss for Internal Combustion Engine Considering the Hydrodynamic Oil Film Pressure". In SAE International Congress and Exposition. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1989. http://dx.doi.org/10.4271/890138.
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Krishna Kumar, B., C. Jebaraj, S. Manivasagam e R. Mahadevan. "Piston Pin Hole Design Improvement for Engines of Higher Rating". In ASME 2005 Internal Combustion Engine Division Fall Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/icef2005-1312.
Abstract (sommario):
This paper studies the effect of design improvements generally prescribed for the piston pin hole on induced stresses with the help of finite element analysis techniques. This decade has seen a very significant increase in the load rating of internal combustion engines. The engines develop a pressure to the tune of 180 bar and more, which needs to be supported by the pin hole, which rests on the piston pin. Predictions of the effect of the increased load on the pin hole and design modifications to support the higher load have become very important activities during the course of piston development. Two design modification options are studied in this paper. The first modification is based on reducing stress concentration by suitably machining a taper profile for a pre-calculated distance at the inner boss zone. The second modification is carried out by having pin hole longitudinal relieves, popularly known as lube slots. Any modification carried out in the pin hole has an influence on the stress distribution at the bowl zone. Therefore, in addition to the pin hole stress, a thorough study on the stress distribution in the bowl zone is also carried out. The numerical results obtained for the modified designs are compared with the base line configuration and the effects of the modifications are discussed in detail. The modifications are found to have a significant effect in reducing the pin hole hoop stress, which is tensile in nature. But at the same time, it has been observed that the tensile hoop stress value in the bowl area increases. Therefore, it is concluded that the suggested pin hole improvements can be carried out if the induced hoop stress values do not exceed the prescribed values for the selected material. Further studies were made to analyze the influence of thermal loading on the stress induced and also to analyze the influence of combined (mechanical and thermal) loading on the induced stress. The thermal hoop stress were compressive in nature and hence its influence on the combined loading is significant. In this paper the results are normalized and shown as tables and figures.
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Jain, Naman, e Vaibhav Arghode. "Development of a Standalone, Liquid Fuelled Miniature Power Generation System". In ASME 2017 Power Conference Joint With ICOPE-17 collocated with the ASME 2017 11th International Conference on Energy Sustainability, the ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, and the ASME 2017 Nuclear Forum. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/power-icope2017-3327.
Abstract (sommario):
This paper aims at developing a mesoscale combustion based thermoelectric power generator as an alternate to the electrochemical batteries. Most of the micro and mesoscale combustors investigated till date are based on external fuel and air supply systems, which may not be beneficial for a practical system. The proposed design is a standalone system which makes use of the heat conducted through the combustor walls, as an energy source to evaporate the liquid fuel stored in a surrounding tank and supply the vaporized fuel to the combustor. The high momentum fuel (vapor) jet is designed to entrain the ambient air in appropriate proportion so as to form a combustible mixture. The partially mixed fuel/air mixture is fed to a mesoscale combustor and the flame is stabilized by facilitating hot gas recirculation regions. The heat conduction through the combustor walls is controlled by providing an air gap between two concentric, low thermal conductivity, ceramic tubes so as to transmit desirable amount of heat to the fuel tank. Note that the heat lost from the combustor, is recovered via increased enthalpy of the supplied fuel. The hot products then flow over the hot side of a thermoelectric module to generate electricity. The cold side of the module is maintained at relatively lower temperature and the rejected heat is used to boil the stored water. The prototype is designed to produce an electrical power output of 15 W with an overall efficiency of about 3% and endurance of 1 hour in a single fuel (and cold side water) refill. The paper presents detailed thermo-fluid and heat transfer analysis of the constituent components and evaluates the performance of the system.
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Gounder, James D., Anton Zizin, Oliver Lammel e Manfred Aigner. "Spray Characteristics Measured in a New FLOX® Based Low Emission Combustor for Liquid Fuels Using Laser and Optical Diagnostics". In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56629.
Abstract (sommario):
A liquid fuel combustor based on the FLOX® burner concept has been developed for application in a Micro Gas Turbine (MGT) Range Extender (REX) for next generation cars. The characterization of this combustor was performed at the High Pressure Optical Test rig (HIPOT) at DLR Stuttgart. The operability limits of the burner were mapped out for full load conditions at 3.5 bars by varying global lambda (λG) from 1.25–2.00 and bulk jet velocity (vBulk) from 80–140 m/s. Exhaust gas measurements show NOx and CO levels below 5 and 10 ppm respectively (corrected for reference 15% O2) at λG = 1.89. Optical and laser diagnostic measurement techniques have been employed to characterize the spray flames. The flames at stable burner operation points (BOPs) show a predominantly jet like flame shape irrespective of λG and vBulk. Droplets in the size range 2–40 μm have been measured close to the nozzle exit plane. Velocities conditioned on the droplet size show large droplets d > 15 μm transitioning from negative slip velocity at the exit plane to positive slip velocity at downstream location. The positive slip velocities and slow evaporation of large droplets lead to droplets travelling further into the combustion chamber and hence resulting in long flames. A comprehensive data set for the spray characteristic of the new liquid FLOX® burner is made available.