Letteratura scientifica selezionata sul tema "Thermo-Kinetics"
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Articoli di riviste sul tema "Thermo-Kinetics":
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Yuan, Chun Miao, Chang Li, Gang Li e Pei Hong Zhang. "Determination of Kinetic Parameters of Maize Starch in Air Using Thermogravimetric Analysis". Advanced Materials Research 508 (aprile 2012): 114–17. http://dx.doi.org/10.4028/www.scientific.net/amr.508.114.
Abstract (sommario):
Maize starch is abundant in quantity in China. The hazard from dust explosion of maize starch was very great. Number simulation is a good way to predict the consequent of dust explosion, but the known of reaction kinetics of hazardous materials is necessary. The objective of this research was to determine the reaction kinetics of maize starch using thermo-gravimetric analyses. Thermo-gravimetric analyses of maize starch were performed at heating rates of 5, 10, and 15 min-1 in an air atmospheres. The weight losses of maize starch in an air atmosphere were found to occur in three stages. The parameters of the reaction kinetics were obtained in Stage and .
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Nawab, Yasir, Chung Hae Park, Abdelghani Saouab, Romain Agogué e Pierre Beauchêne. "Modeling the Residual Stress in Woven Thermoset Composites Parts for Aerospace Applications Using Finite Element Methods". Advanced Materials Research 1099 (aprile 2015): 32–36. http://dx.doi.org/10.4028/www.scientific.net/amr.1099.32.
Abstract (sommario):
Process induced residual stresses in thermoset composite parts is one of significant issue faced by the industry. Its Modelling is a coupled multiphysics phenomena. Precise information about the chemical shrinkage, thermal expansion coefficient, cure kinetics, heat transfer and constitutive equation are required for an accurate simulation. In this article, spring-in angle induced in woven carbon/epoxy composite bracket is modelled by solving the thermo-kinetics and thermo-mechanics coupling simultaneously in a commercial finite element software. The obtained values of spring-in angle using numerical simulation are compared with those found in the literature and both are found in agreement.
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Mandal, Dev K., Haripada Bhunia, Pramod K. Bajpai, Kumar A. Dubey, Lalit Varshney e Gaurav Madhu. "Thermo-oxidative degradation kinetics of grafted polypropylene films". Radiation Effects and Defects in Solids 172, n. 11-12 (2 dicembre 2017): 878–95. http://dx.doi.org/10.1080/10420150.2017.1417411.
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Versan KOK, Mustafa. "Thermo-oxidative characterization and kinetics of tar sands". Energy 36, n. 8 (agosto 2011): 5338–42. http://dx.doi.org/10.1016/j.energy.2011.06.042.
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Rojas Reyes, Néstor Ricardo, Luver Echeverry Vargas e Sebastián Sierra Pérez. "Thermo-kinetics of lead leaching from recycled batteries". Ingeniería y Desarrollo 36, n. 1 (1 gennaio 2018): 155–71. http://dx.doi.org/10.14482/inde.36.1.10944.
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Zapata, B., J. Balmaseda, E. Fregoso-Israel e E. Torres-García. "Thermo-kinetics study of orange peel in air". Journal of Thermal Analysis and Calorimetry 98, n. 1 (12 agosto 2009): 309–15. http://dx.doi.org/10.1007/s10973-009-0146-9.
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Rubanik, Vasili V., Vasili V. Rubanik Jr. e Olga A. Petrova-Burkina. "Peculiarities of Thermoelectric Force Behaviour in Nikelide Titane upon Non-Stationary Heating". Materials Science Forum 738-739 (gennaio 2013): 292–96. http://dx.doi.org/10.4028/www.scientific.net/msf.738-739.292.
Abstract (sommario):
The phenomena of appearance of thermo-emf at non-stationary heating in equiatomic titanium nickelide was examined. The peculiarities of kinetics of display of thermokinetic emf, also during thermocycling were determined. The possibility of generation of thermo-emf in amorphous-crystalline ribbon of Ti50Ni25Cu25 during the transition to crystalline state was determined.
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Yuan, Hao, Ming Yuan Zhou, Jie Guan, Li Fan, Chang Wen Ma e Zhao Hui Ou Yang. "Recovering High-Water Ti-Gypsum Using Thermo-Compression Drying Technology". Applied Mechanics and Materials 448-453 (ottobre 2013): 746–51. http://dx.doi.org/10.4028/www.scientific.net/amm.448-453.746.
Abstract (sommario):
The paper elaborates on the operating principle and technical features of thermo-compression drying process, the kinetics involved in the dewatering process, and the technological process system and equipment used. It is demonstrated by the case of the treatment of Ti-Gypsum using the thermo-compression drying process that the moisture of the products can reach 30%.
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Zhou, Ming Yuan, Li Fan, Xiu Li Li e Chang Wen Ma. "Recovering Tail Mine from a Coal Preparation Plant Using Non-Phase-Change Thermo-Compression Drying Technology". Advanced Materials Research 361-363 (ottobre 2011): 337–42. http://dx.doi.org/10.4028/www.scientific.net/amr.361-363.337.
Abstract (sommario):
The paper elaborates on the operating principle and technical features of the thermo-compression drying process, the kinetics involved in the dewatering process, and the technological process system and equipment used. It is demonstrated by the case of the treatment of tail mine using the thermo-compression drying process that the moisture content of the products can reach lower than 12%.
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Wang, Yuan Xiao, Xiu Fen Wang e Shi Wei Song. "Synthesis, Characterization and Controlled Drug Release of Thermosensitive Poly(NIPAAm-co-HEMA) and IPN(NIPAAm/HEMA) Hydrogels". Advanced Materials Research 11-12 (febbraio 2006): 737–40. http://dx.doi.org/10.4028/www.scientific.net/amr.11-12.737.
Abstract (sommario):
A series of thermo-sensitive copolymers and interpenetrating network hydrogels were prepared using PNIPAAm and HEMA.The effects of the PNIPAAm/HEMA ratio on the swelling ratio ,and deswelling and reswelling kinetics of gels at different temperatures and drug release characteristics in vitro were discussed. The results showed that the copolymer and IPN hydrogels exhibited thermo-sensitive swelling characteristics. Therefore, the hydrogels may be useful in the controlled drug delivery systems.
Tesi sul tema "Thermo-Kinetics":
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Muralidas, Pooja. "Thermo-gravimetric Analysis of Corrosion Kinetics of Ti and Zr Coated P91 Steel". OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/2057.
Abstract (sommario):
In recent decade growing concerns of CO2 emissions from power plants have increased, which led to development of technologies like oxy-fuel combustion process. P91 steel is profoundly used in power plants, but oxy fuel combustion exacerbates corrosion due to recycling of flue gas. This paper studied the kinetics of the corrosion rate on the boiler tubes and furnace and help achieve a corrosion resistant coating over it. Refractory metal diffusion coating is created and tested at high temperature in corrosive atmosphere. This was done by forming Ti and Zr diffusion coating on P91 steel using pack cementation. Coating thickness of 12 and 20 µm were obtained for Ti and Zr respectively. These samples were tested in thermo-gravimetric system by heating at 950˚C for 24 hours in 5% oxygen in Helium gas. Heating in an oxidizing environment lead to exfoliation corrosion on uncoated P91 steel. TGA procedure confirmed less mass change of Ti and Zr coated samples, than that of uncoated P91 steel sample. SEM and depth profiling confirms oxygen penetration is 2.7mm in uncoated P91 steel sample, whereas the Ti and Zr Coated samples oxygen penetration is just 16 and 56 µm respectively.
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Tita, Bertrand Asongwe. "Waste-to-Energy : A study on Reaction Kinetics of Tropical Wood Sawdust". Thesis, Högskolan i Borås, Akademin för textil, teknik och ekonomi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-9746.
Abstract (sommario):
The reaction kinetics of Iroko and Mahogany were studied using TGA. The pyrolysis process was achieved using six different heating rates of 2,5,8,12,15 and 20˚C. A 15˚C/min heating rate was used for gasification in steam at different temperatures while varying the concentrations of nitrogen and steam in the process. The kinetic parameters, activation energy and pre exponential factor, were obtained by implementing two chosen kinetic models. These models are: Friedman’s Iso-conversional Method, Flynn-Wall-Ozawa Method (FWO). There were substantial differences in the values of the kinetic triplets found from the experiments. Due to the substantial differences in the values, it was not the best way to perform this kind of analysis (which is the traditional way) but instead to use pure regression analysis; but using it for the whole data set (that means for all heating rates) and minimize the difference with experimental data.
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Brown, Tracy. "Investigation of the rheology, cure kinetics, and thermo-mechanical properties of GRC-A loaded with zeolites". DigitalCommons@Robert W. Woodruff Library, Atlanta University Center, 2010. http://digitalcommons.auctr.edu/dissertations/256.
Abstract (sommario):
Phenylethynyl terminated imides (PETI) are high temperature, high performance matrix resins that can be processed into composites by various methods including resin transfer molding (RTM) arid vacuum assisted resin transfer molding (VARTM). PETI resins have experienced extremely rapid development in recent years, with major emphasis placed on engineering applications that take advantage of their high cured TgS,high thermooxidative stability, high strength to weight ratio, outstanding mechanical properties, and compatibility with RTM and VARTM processing. In recent years the addition of nanoparticles to resin systems has been shown to further enhance the mechanical properties and thermooxidative stability. In this study, we incorporated nanoporous aluminosilicate materials, otherwise known as zeolites, into PETI resin GRC-A, and investigated the effect the zeolites have on the viscosity, cure kinetics, thermooxidative stability and other thermomechanical properties of GRC-A. Rheological and differential scanning calorimetry studies conducted on the GRC-Alzeolite mixtures showed that zeolite L acts like a filler and retards the curing of the phenylethynyl end-groups, while zeolite Y catalyzes the curing process. Additionally, cure kinetic studies via melt rheology and DSC confirmed that the activation energies for GRC-A/zeolite Y mixtures as lower than for neat GRC-A and GRC-A/zeolite L mixtures, further supporting zeolite L acts as a filler while zeolite Y serves as a catalyst during the cure process. While the cured Tgs, from the DMA and TMA studies showed that in spite of the catalytic properties of zeolite Y; it did not afford additional properties over GRC-A and zeolite L mixtures. However, the catalytic properties of zeolite Y allows PETI resins to be cured at a lower temperatures, which could lead to lower energy costs in the production of composite parts from PETI resins.
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Al-Salem, S. "Thermo-Chemical Treatment (TCT) of polymers in multi-scale reactors : a kinetics and Life Cycle Assessment (LCA) study". Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1394441/.
Abstract (sommario):
The main reasons behind the success of the petrochemicals industry are not only the vast array of products that it provides - considered vital to our daily functions - but also the added value that it brings to the crude oil barrel price, making it a reliable venture for any concerned party. However, the industry is now faced with a fluctuating market and an unstable economy, which makes it imperative to find a more abundant and sustainable feedstock. Of all petrochemical derivatives, polymers (and their related industries) occupy the major share, and this makes the plastics industry a growing sector in terms of processing and conversion. Both virgin and waste plastics represent an attractive source of energy and product recovery. The main objective of this work was to investigate the thermo-chemical treatment (TCT) of polymers at different scales, and the reactors studied ranged from micro laboratory scale to industrial units suitable for covering large market demands. Within this framework, the degressive behaviour of polyolefin polymers (three virgin grades and two recyclate ones) was investigated alongside the products yielded (gases (C1-C4), liquids (non-aromatic C5-C10), aromatics (single ring structures) and waxes (> C11). This was achieved in a micro scale isothermal pyrolysis process, using 15 mg in a laboratory thermogravimetric analyser covering the temperature range of 500-600°C. The analysis led to the development of an nth order novel model on the basis of lumped products yielded by pyrolysis. The degradation mechanism was used to develop the mathematical breakdown of the primary, secondary and tertiary reactions. The model developed predicts the yield of the four different products and the polymer residual fraction at any operating condition proving to be a useful tool for reactor design and simulation, where the production of a specific chemical at a certain operating condition is paramount. In addition, laboratory scale isothermal pyrolysis experiments on end of life tyres (ELTs) were also conducted. This was achieved as a means to demonstrate the application of the concept previously applied to the polyolefins. A thermal cracking (degradation) scheme was proposed based on the global yielded products, which were lumped into four categories, namely gases (C1-C4), liquids (non-aromatic C5-C10), single ring aromatics (C5-C10), and char. The depolymerization kinetics (from primary, secondary and tertiary reactions) evaluation showed a high match with the experimental results obtained in this work. Finally, a life cycle assessment (LCA) was conducted for three integrated scenarios that reflect the current (2012) treatment of waste plastics in the Greater London area. The scenarios studied utilised a fraction of the polymers treated as a feedstock for two industrial scale TCT technologies; namely a low-temperature pyrolysis reactor that works using BP® technology and a hydrocracking unit that utilises the Veba-Combi Cracking (VCC®) concept. The scenarios studied also include transfer stations, a dry materials recovery facility (MRF) and a combined heat and power (CHP) incineration unit. The energy recovered via the different processes studied, as well as the chemicals and petrochemicals recovered, were all considered as credits in the LCA conducted. Chemicals obtained by the TCT units are very valuable and can replace refinery cuts and petrochemicals (e.g. syncrude (crude oil), naphtha, heavy (waxes) fraction (comparable to atmospheric residue), gases (C3 and C4) refinery cuts, etc.). This led to a technoeconomic analysis of the three integrated scenarios in order to assess the overall profitability. The analysis included capital, operating and maintenance costs, gate fees, transportation costs and corporation tax. The eligibility for governmental incentives (i.e. renewable obligation certificates (ROCs), levy exemption certificates (LECs) and packaging recovery notes (PRNs)) was also considered. The results obtained from the work carried out and reported in this thesis point towards ideal strategies for the treatment of polymers within the urban environment. It also provides a detailed understanding of potential products from polymers introduced to TCT units. This also aids the optimum recovery of petrochemicals, chemicals and energy from different TCT processes, and could help the UK Government in meeting its energy policy targets. It can also contribute to the energy security through diversification of supply. Finally, it provides a perspective on the integration between the crude oil upstream industry and different petrochemical complexes and oil refineries, through the use of different TCT units to increase the production of petrochemicals in existing plants.
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Bhagavatula, Abhijit. "THERMO-CHEMICAL CONVERSION OF COAL-BIOMASS BLENDS: KINETICS MODELING OF PYROLYSIS, MOVING BED GASIFICATION AND STABLE CARBON ISOTOPE ANALYSIS". UKnowledge, 2014. http://uknowledge.uky.edu/cme_etds/43.
Abstract (sommario):
The past few years have seen an upsurge in the use of renewable biomass as a source of energy due to growing concerns over greenhouse gas emissions caused by the combustion of fossil fuels and the need for energy independence due to depleting fossil fuel resources. Although coal will continue to be a major source of energy for many years, there is still great interest in replacing part of the coal used in energy generation with renewable biomass. Combustion converts inherent chemical energy of carbonaceous feedstock to only thermal energy. On the other hand, partial oxidation processes like gasification convert chemical energy into thermal energy as well as synthesis gas which can be easily stored or transported using existing infrastructure for downstream chemical conversion to higher value specialty chemicals as well as production of heat, hydrogen, and power.
Devolatilization or pyrolysis plays an important role during gasification and is considered to be the starting point for all heterogeneous gasification reactions. Pyrolysis kinetic modeling is, therefore, an important step in analyzing interactions between blended feedstocks. The thermal evolution profiles of different coal-biomass blends were investigated at various heating rates using thermogravimetric analysis. Using MATLAB, complex models for devolatilization of the blends were solved for obtaining and predicting the global kinetic parameters. Parallel first order reactions model, distributed activation energy model and matrix inversion algorithm were utilized and compared for this purpose. Using these global kinetic parameters, devolatilization rates of unknown fuel blends gasified at unknown heating rates can be accurately predicted using the matrix inversion method.
A unique laboratory scale auto-thermal moving bed gasifier was also designed and constructed for studying the thermochemical conversion of coal-biomass blends. The effect of varying operating parameters was analyzed for optimizing syngas production. In addition, stable carbon isotope analysis using Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry (GC-C-IRMS) was used for qualitatively and quantitatively measuring individual contributions of coal and biomass feedstocks for generation of carbonaceous gases during gasification. The predictive models utilized and experimental data obtained via these methods can provide valuable information for analyzing synergistic interactions between feedstocks and also for process modeling and optimization.
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Couchet, Clélia. "New insights in understanding the interaction between recrystallization and phase transformation during intercritical annealing in DP steels". Electronic Thesis or Diss., Université de Lorraine, 2024. http://www.theses.fr/2024LORR0019.
Abstract (sommario):
La formation des microstructures est cruciale pour la sidérurgie. Pour les aciers Dual Phase (DP), utilisés dans l'automobile, celle-ci a lieu lors du recuit intercritique après le laminage à froid. Après la chauffe, la microstructure est composée de ferrite et d'austénite recristallisées. Lors du refroidissement, l'austénite se transforme partiellement en ferrite puis en martensite pour atteindre la microstructure ferrite/martensite finale. L'austénitisation est cruciale pour contrôler les fractions et tailles de phase finales et donc leurs propriétés mécaniques. De nombreuses études montrent que la vitesse de chauffe contrôle la cinétique de transformation et la morphologie de l'austénite ("collier" ou "bande"). Ces effets sont souvent attribués au chevauchement entre la recristallisation de la ferrite et la formation de l'austénite, mais les mécanismes sous-jacents restent controversés. En utilisant les progrès récents dans les expériences in situ sur les lignes de faisceaux synchrotron, ce travail de doctorat vise à proposer une nouvelle compréhension des interactions entre la recristallisation de la ferrite et la formation de l'austénite et à développer un modèle prédictif pour la cinétique de formation de l'austénite. Le développement expérimental principal de cette thèse est une nouvelle technique d'analyse basée sur la diffraction des rayons X de haute énergie pour suivre in situ la recristallisation et les transformations de phase pendant la phase de recuit, y compris à des vitesses de chauffe élevées. Notre nouvelle méthode, appelée Isolated Diffraction Spot Tracking (IDST), est d'abord validée pour étudier la recristallisation sur des aciers ferritiques modèles. Ces mesures in situ sont complétées par des observations des microstructures après traitements interrompus en microscopie (optique, microscopie électronique à balayage et à transmission), et par des mesures de chimie locale (spectroscopie de rayons X à dispersion d'énergie et de dispersion en longueur d'onde). Nous reproduisons d'abord des expériences pour étudier l'influence de la vitesse de chauffe sur l'acier étudié pendant le recuit intercritique. Dans celles-ci, le chevauchement entre la recristallisation de la ferrite et la formation de l'austénite est régi par la vitesse de chauffe. Ensuite, nous avons conçu des expériences pour décorréler l'effet de la vitesse de chauffe et ce chevauchement. La vitesse de chauffe est fixée pour maintenir les mêmes conditions pour les mécanismes thermo-activés, mais le micro-alliage au niobium et le taux de laminage à froid plus faible retardent la recristallisation de la ferrite. Ces expériences montrent que la cinétique de transformation de l'austénite n'est pas contrôlée par la recristallisation, mais par la seule condition thermodynamique de l'interface de transformation et peut-être par la distance de diffusion dans les microstructures. Enfin, une analyse thermocinétique détaillée des mécanismes de formation de l'austénite au cours du recuit intercritique est proposée sur la base de simulations DICTRA/Thermo-Calc et de notre travail expérimental. L'effet des éléments d'alliage mineurs sur la cinétique de croissance de l'austénite est étudié et un modèle prédictif pour la formation de l'austénite pendant le recuit intercritique est développé. Finalement, ce travail montre l'absence d'effet significatif de la concomitance des mécanismes étudiés sur la cinétique de formation de l'austénite au cours de la chauffe. Nous montrons que la cinétique de formation de l'austénite est contrôlée par la diffusion. La différence de cinétique de formation de l'austénite au cours de la phase de maintien est expliquée par des considérations microstructurales, affectant les distances de diffusionThe formation of microstructures is a crucial step for steelmakers. In the case of DP steels, used for automotive construction, this formation takes place during intercritical annealing after cold-rolling. During this thermal treatment, after the heating step, the microstructure is made of recrystallized ferrite and austenite. During cooling, the austenite partially transforms into ferrite and then into martensite to reach the expected final ferrite/martensite microstructure. The austenitization step is therefore crucial for the manufacturers of these steels, to control the final phase fractions and sizes and, consequently, their mechanical properties. Numerous studies show that the heating rate controls the transformation kinetics and the morphology of the austenite ("necklace" or "banded"), but the underlying mechanisms remains a bone of contention. The overlap between ferrite recrystallization and austenite formation is often made responsible for these effects, through different mechanisms. Using recent advances in in situ experiments on synchrotron beamlines, this PhD proposes a new insight in the understanding of the interactions between ferrite recrystallization and austenite formation and develops a predictive model for the austenite formation kinetics. The main experimental development of this thesis is a new coupled time-resolved analysis technique, based on in situ High-Energy X-Ray Diffraction to track recrystallization and phase transformations during the annealing phase, including at high heating speeds. Our new method, called Isolated Diffraction Spot Tracking (IDST), is first validated to study recrystallization on model ferritic steels. These in situ measurements are supplemented by observations of microstructures after interrupted treatments in microscopy (optical, Scanning Electron Microscopy and Transmission Electron Microscopy), and from local chemistry measurements (Energy-Dispersive X-ray Spectroscopy and Wavelength Dispersion Spectroscopy)We first reproduce experiments to study the influence of the heating rate on the studied steel during the intercritical annealing. In such experiments, the overlap between ferrite recrystallization and austenite formation is governed by the heating rate. To go further, we designed experiments to decorrelate the effect of the heating rate and this overlap. During these, the heating rate is fixed to maintain the same conditions for thermo-activated mechanisms, but the niobium micro-alloying and lower cold-rolling ratio are used to delay ferrite recrystallization. These experiments show unambiguously that austenite transformation kinetics is not controlled by the recrystallization, but by the sole thermodynamic condition of interfaces and maybe by the diffusion distance in the microstructures. Finally, we propose a detailed thermo-kinetics analysis of the mechanisms of austenite formation during the intercritical annealing based on DICTRA/Thermo-Calc simulations and on our experimental work. The effect of minor alloying elements on the austenite growth kinetics is investigated. This work finally proposes new predictive models for austenite formation during the intercritical annealing. This PhD work finally shows no significant effect of the concomitance of the two studied mechanisms on the austenite formation kinetics along the heating stage. We demonstrate that the austenite formation kinetics is diffusion-controlled. The difference in austenite formation kinetics along the holding stage is explained by microstructural considerations, affecting the diffusion distances
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Maach, Nicolas. "Modélisation cinétique de l'hydratation en systèmes dilués des aluminates de calcium : Des mécanismes chimiques aux modélisations par les Population Balance Equations". Thesis, Lyon, 2019. http://www.theses.fr/2019LYSEI127.
Abstract (sommario):
Ces travaux s’articulent autour de la modélisation cinétique de l’hydratation des ciments alumino-calciques (CAC) pour en améliorer la compréhension et la maîtrise. L’aspect cinétique pour ces ciments est essentiel en raison des nombreux états métastables qu’ils traversent (e.g. conversion).Des modèles de cinétique intégrés dans l’espace existent déjà pour simuler des pâtes de mortier mais ils requièrent la connaissance des lois de cinétiques. Malheureusement, ces lois sont mal identifiées pour les CAC et c’est ce qui motive la création d’un modèle pour des suspensions minérales. L’étude de suspensions permet d’étudier ces lois sans l’influence de l’empilement granulaire et du réseau poreux. Le modèle créé est un modèle de thermochimie où les quantités de matières sont pilotées par des équations différentielles-algébriques. L’information sur la granulométrie est, elle, portée par des Population Balance Equations permettant de répercuter chaque phénomène physico-chimiques (e.g. Nucléation, Dissolution, Croissance, Agglomération...) de manière adaptable et indépendante sur les tailles de particules. L’étude de ce modèle a permis de mettre en évidence le rôle fondamental que joue la formation de l’hydroxyde d’aluminium dans l’hydratation des CAC. Cette formation permet l’apport en solution d’ions hydroxyde déficitaires à la formation de la plupart des hydrates en consommant des ions aluminates. Cette formation d’hydroxyde d’aluminium a été démontrée comme étant complexe à expliquer expérimentalement et à modéliser. Toutefois, l’utilisation de précurseurs pré-hydroxylés permet de la modéliser partiellementThis work focuses on the kinetic modeling of calcium aluminate cements (CAC) to improve the knowledge and the control of these chemical systems. The kinetic aspect of this modeling is essential since their hydration goes through several metastable states (e.g. CAC conversion). Kinetic models integrated over a volume of mortar paste already exist yet they require appropriate kinetic laws. Unfortunately, these laws are poorly identified for CACs and this is what motivates the creation of a model for mineral suspensions. The simulation of suspension allows the evaluation of these kinetic laws without the interference of granular stacking or porous network assumptions. The created model is a thermo-chemical model where the molar quantities are driven by differential-algebraic equations. The particle size information is borne by Population Balance Equations allowing to manage each physic-chemical phenomenon (e.g. Nucleation, Dissolution, Growth, Agglomeration...) independently and in a flexible way. The evaluation of this model highlighted the key role of aluminium hydroxide formation in CAC hydration. This reaction converts the excess of aluminate ions into the deficient hydroxide ion which are required by most of the hydrates. This work demonstrated that aluminium hydroxide formation is complex to explain experimentally and to model. Nevertheless, the use of prehydroxylated precursors allows a partial modeling of this reaction
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Wessman, Sten. "Applications of Computational Thermodynamics and Kinetics on Transformations in Stainless Steels". Doctoral thesis, KTH, Skolan för industriell teknik och management (ITM), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-121337.
Abstract (sommario):
Stainless steels are high-alloyed, usually with multiple components and often also dual matrix phases, as for duplex stainless steels. This make predictions and calculations of alloying effects on equilibria and transformations complicated. Computational thermodynamics has emerged as an indispensable tool for calculations within these complex systems with predictions of equilibria and precipitation of phases. This thesis offers examples illustrating how computational methods can be applied both to thermodynamics, kinetics and coarsening of stainless steels in order to predict microstructure and, to some extent, also properties. The performance of a current state-of-the-art commercial thermodynamic database was also explored and strengths and weaknesses highlighted.QC 20130429
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Souza, Luiz Augusto Gesteira de. "Cálculos usando métodos de estrutura eletrônica na obtenção de parâmetros cinéticos e termoquímicos". Universidade de São Paulo, 2003. http://www.teses.usp.br/teses/disponiveis/46/46132/tde-08022018-090432/.
Abstract (sommario):
Cálculos usando métodos de estrutura eletrônica (Hartree-Fock, Mõller-Plesset de segunda ordem e DFT, B3LYP) foram efetuados pelo programa Gaussian98 em microcomputadores e estações de trabalho, com o objetivo de elucidar os canais de decomposição unimolecular de éter dietílico em fase gasosa e foram comparados com valores obtidos através de aproximações baseadas na mecânica estatística pela metodologia de Benson. O éter dietílico vem sendo usado como um aditivo para o óleo diesel e combustível alternativo e o conhecimento de suas vias vias de decomposição é fundamental nestas investigações. Dezesseis modos primários, do qual, quatro ocorrem através de cisão de ligações simples C-O, C-C,C(1)-H e C(2)-H e doze ocorrendo através de estados de transição cíclicos, os quais eliminam produtos como hidrogênio etano, acetaldeído, etano, álcool etílico, metil etil éter, metano, alguns carbenos e também di-radicais, foram considerados para a determinação das barreiras de ativação, entalpias de reação, entropias de reação e energia livre de Gibbs de reação. Vias primárias ocorrendo através de cisão de ligação, não reproduziram os valores experimentais para as barreiras de ativação, mas reproduziram de modo significante, valores da entalpia da reação. Eliminação de eteno e álcool etílico, ocorrendo através de um estado de transição de quatro centros, apresentou a barreira de ativação mais baixa. Acetaldeído e eliminação de etano, ocorrendo através de quatro centros, apresentou barreira significativamente alta, mas por outro lado, a menor entalpia, ligeiramente exotérmica por -0,8 kcal.mol-1. Eliminações 1,2 de metano e carbeno ocorrendo através de três centros, junto com a eliminação 1, 1 de hidrogênio e carbeno por três centros, eliminação 2,2 hidrogênio e carbeno por três centros e eliminação 1,4 de hidrogênio, acetaldeído e eteno por seis centros, apresentaram barreiras de ativação relativamente próximas mostrando que elas são competitivas entre si. Os valores computados dos canais que ocorrem por estados de transição cíclicos foram comparados com os resultados experimentais disponíveis e discutida a validade desta abordagem computacional para o estudo de reações unimoleculares de multi-canais. Determinação de parâmetros termoquímicos, como calor de formação para espécies radicalares dos canais de decomposição primário e alguns radicais alcóxidos, junto com a estimativa de afinidade eletrônica e protônica (com a abordagem ab initio Gaussian 2 a qual estima energias eletrônicas muito precisas) foram efetuados e seus resultados foram comparados com os valores experimentais disponíveis e valores obtidos através de energias de ligação e da regra de aditividade de Benson.Calculations using methods of electronic structure(Hartree-Fock, second order Moller-Plesset and DFT: B3LYP) had been effected through the Gaussian98 program in microcomputers and workstations, with the objective to elucidate the unimolecular decomposition channels of diethyl ether in gaseous phase. These results also had been compared to those obtained by the methodology based in statistical mechanics through Benson\'s approach. Sixteen primary ways, which, four occur through the break of simple bonds C-O, C-C,C(1)-H, C(2)-H, and twelve occur through cyclical transistion states, which eliminate products as hydrogen, ethene, acetaldehyde, ethane, ethyl alcohol, methyl ethyl ether, methane, some carbenes and also diradicals. These products had been considered to the determination of the activation barriers, enthalpies of reaction, entropies of reaction and free energy of Gibbs of reaction. Primary ways occurring through the break of bonds, had not reproduced experimental values for the activation barriers, however they had reproduced in a significant way, values of the enthalpy of the reaction. Elimination of ethene and ethyl alcohol, occurring by a transition state of four centers, presented the lowest activation barrier. Acetaldehyde and ethane elimination occurring through four centers, presented a high significantly barrier, but on the other hand it presented the smallest enthalpy, lightly exothermic above -0,8 kcal.mol-1. Eliminations 1,2 of methane and carbene occurring through three centers, together with the elimination 1,1 of hydrogen and carbene through three centers, elimination 2,2 of hydrogen and carbene through three centers and elimination 1,4 of hydrogen, acetaldehyde and ethene through six centers, had presented relatively next activation barriers, showing that they are competitive among themselves. The computed values of the channels that occur through cyclical transition states had been compared with the available experimental results and the trustworthiness of this computational boarding for the study of unimolecular reactions in multi-channel had been dicussed. Determination of thermochemical parameters, as heat of formation for radicalar species of the primary channel of decomposition and some alcoxyde radicais, together with the estimative of the electronic and protonic affinities,( with the ab initio Gaussian 2 boarding which estimate very precise eletronic energies ) and their results had been compared with the available experimental values and with values gotten through energies of bond and Benson\'s additivity rule.
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Duchatel, Xavier. "Dégradation thermo-oxydante du poly(fluorure de vinylidène)". Rouen, 1996. http://www.theses.fr/1996ROUES009.
Abstract (sommario):
Le PVDF, réputé particulièrement stable chimiquement et thermiquement, est largement utilisé dans le domaine du forage pétrolier « off shore ». Dans ce type d'utilisation, la contrainte en température peut atteindre plus de 140°C. Or, jusqu'à présent, la plupart des études de dégradation menées ont été faites à des températures très supérieures. Nous avons étudié les différentes réactions de dégradation du PVDF sur une large gamme de température (400 à 140°C) dans des atmosphères neutres ou oxydantes. Il s'est avéré que la déhydrofluoration et la réticulation étaient les principaux phénomènes de dégradation, ainsi que l'oxydation en présence d'oxygène. La déhydrofluoration a tout particulièrement été étudiée et modélisée au début de la dégradation. Des différences de comportement entre l'état fondu et semi-cristallin ont permis de conclure que les zones cristallines étaient plus sensibles thermiquement que les zones amorphes ; chaque phase cristalline ayant sa propre cinétique. L'action dégradante du DMF et de différentes amines a également été étudiée. Il s'avère que la dégradation en solution se traduit majoritairement par une déhydrofluoration et des coupures de chaîne.
Capitoli di libri sul tema "Thermo-Kinetics":
1
Amira, Sellami, Guesmi Mohamed Hedi e Elleuch Riadh. "Enhanced Disc Brake Thermo-Kinetics for Better Wear Test Reproducibility". In Applied Condition Monitoring, 425–32. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-34190-8_45.
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Salomon, Anton, Mykhaylo Motylenko, Martin Thümmler e David Rafaja. "Interface Reactions Between the Metal Melt and the Filter Surface Activated by a Spark Plasma Sintering Process". In Multifunctional Ceramic Filter Systems for Metal Melt Filtration, 163–90. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-40930-1_7.
Abstract (sommario):
AbstractThe reactions between newly developed filter materials and metal melts containing various inclusions were analyzed under laboratory conditions. For the melt production, a Spark Plasma Sintering (SPS) apparatus was utilized. The SPS process provides very high heating rates, which emulate the thermo-shock during a real filtration process, and variable reaction times, which allows to simulate both, short and long filtration processes. The short-time filtration processes are relevant for die-casting, where one ton of a steel passes the filter in approx. 15 s, the long-term ones for continuous casting taking several hours. In the SPS process, the convection of the steel melt is suspended, which makes the interpretation of the interfacial reactions and reaction kinetics more straightforward and trustworthy. Furthermore, the SPS process allows speeding up the reaction diffusion kinetics by using tiny diffusion couples having the form of powder mixtures that contain the metal or alloy and the functional filter material under study. In such samples, the equilibrium state that is suitable for a direct comparison with the results of thermodynamic simulations can be achieved very quickly.
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Engler, Olaf, L. Löchte e Kai F. Karhausen. "Modelling of Recrystallisation Kinetics and Texture during the Thermo-Mechanical Processing of Aluminium Sheets". In Materials Science Forum, 555–66. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-975-x.555.
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Tran, Trong Tuan, Pierre Girods, Mourad Khelifa, Marc Oudjene e Yann Rogaume. "Characterization of Kinetics of Thermal Decomposition of Densified Wood Materials from Isothermal Thermo-Gravimetric Experiments". In Advances in Mechanical Engineering and Mechanics II, 401–9. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-86446-0_53.
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Aravind, S. L., H. P. Bharath, B. Suresha, B. Harshavardhan, Imran M. Jamadar, P. K. Samal e A. Anand. "Experimental Investigations on the Effect of Carbon Nanotubes and Nanoclay Additives on Thermo-Kinetics and Mechanical Characteristics of Acrylonitrile Butadiene Styrene (ABS)". In Springer Proceedings in Materials, 291–303. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-5567-1_22.
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Sieniutycz, Stanislaw. "Thermodynamics and kinetics of nonequilibrium fluids". In Conservation Laws in Variational Thermo-Hydrodynamics, 87–128. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-1084-6_4.
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Baran, Ismet. "Thermo-kinetics and curing behaviour". In Pultrusion, 49–83. Elsevier, 2023. http://dx.doi.org/10.1016/b978-0-32-391613-4.00005-7.
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Bennamoun, Lyes. "Using Diffusion Model for Prediction and Optimization of Drying Process of Building Material". In Optimization of Design for Better Structural Capacity, 1–23. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7059-2.ch001.
Abstract (sommario):
The aim of this chapter is to confirm the possibility of using the simple diffusion model to predict the behavior of a building material during the application of drying process under variable operating conditions. This approach can be considered as a simulation of the effect of the variable climatic conditions on the building material. During this research, the thermo-physical properties of the tested material as well as the drying air are considered as variable and changing with the operating conditions. Accordingly, diffusion coefficient is determined experimentally and is considered as variable with the temperature and the humidity and represented as function of the wet bulb temperature. Two sorts of conditions are tested: constant flux and convective flux. Furthermore, two types of changes are also tested: sudden changes and progressive changes of the drying conditions. The results of the study are mainly represented by the drying curves or the drying kinetics.
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Margarita Hernandez-Baez, Diana, Alastair Reid, Antonin Chapoy, Bahman Tohidi, Roda Bounaceur e François Montel. "Reactive Transport and Its Implications on Heavy Oil HTGC Analysis. A Coupled Thermo-Hydro-Chemical (THC) Multiphysics Modelling Approach". In Recent Advances in Gas Chromatography [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.98614.
Abstract (sommario):
This chapter provides an insight into the reactive transport in a capillary column which heavy-oil hydrocarbons undergo when analysed by high temperature gas chromatography (HTGC), and their implications on characterisation outcomes, namely thermal cracking of the injected sample; and incomplete or non-elution of heavy components from the column, by using a coupled Thermo-Hydro-Chemical (THC) multiphysics modelling approach. For this purpose, a computational coupled THC, multicomponent, multi-physics model is developed, accounting for: multiphase equilibrium using an in-house, extended thermodynamics distribution factors dataset, up to nC98H198; transport and fluid flow in COMSOL and MATLAB; and chemical reactions using kinetics and mechanisms of the thermal cracking, in CHEMKIN. The determination of the former extended dataset is presented using two complementary HTGC modes: i) High-Efficiency mode, with a long column operated at low flow rate; and ii) true SimDist mode, with a short column operated at high flow rate and elution up to nC100H202.
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J. Ojolo, Sunday, e Musbau G. Sobamowo. "Combating Greenhouse Effects through Biomass Gasification: A Focus on Kinetic Modeling of Combustion and Gasification Zones". In Next-Generation Greenhouses for Food Security. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97331.
Abstract (sommario):
The prevalent challenges of global warming, food security, food production, crop production systems, environment control called for consideration and better utilization of green energy system such as biomass. The advanced thermo-chemical conversion of the renewable energy source which is aimed at production of optimal yield of energy has not been well understood. In order to have better physical insights into the detailed structure of the biomass burning process inside a solid bed, the kinetics of the biomass combustion and gasification must be properly analyzed. Consequently, improved kinetic models of the combustion and gasification zones in the thermochemical conversion system are very required. Therefore, the present study focuses on the development of improved kinetic modeling of the combustion and gasification zones in the biomass gasification system. The performance of the biomass gasifier system is evaluated through the equivalence ratio, the syngas composition, cold gas efficiency and lower heating value. Also, the effects of the equivalent ratio on gas compositions, the gasifier performance and the low heating value of the biomass are analyzed. From the analysis, it is established that the concentration of CO, H2 and CH4 in the gasifier decrease as the equivalence ratio increases. However, CO2 concentration increases with an increase in the equivalence ratio. The cold efficiency and LHV decreases as the equivalence ratio increases while the gas yield increases with an increase in the equivalence ratio. The quantity of gas produced increases as the amount of oxygen consumed increases. Also, the ratio of CO/CO2 decreases as the temperature of the reduction zone increases. Such analysis as presented in this work, is very useful as a time-saving and cost-effective tool for designing and optimizing the biomass gasifier. Therefore, it is evident that this work will play a significant role in the system design including analysis of the distribution of products and ash deposit in the downdraft gasifiers.
Atti di convegni sul tema "Thermo-Kinetics":
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Wang, Ten-See. "Thermo-kinetics characterization of kerosene/RP-1 combustion". In 32nd Joint Propulsion Conference and Exhibit. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1996. http://dx.doi.org/10.2514/6.1996-2887.
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Podzorova, M. V., Yu V. Tertyshnaya, A. A. Popov e S. G. Nikolaeva. "Kinetics of thermo-oxidative degradation of polymer blends based on polylactide". In PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS WITH HIERARCHICAL STRUCTURE FOR NEW TECHNOLOGIES AND RELIABLE STRUCTURES 2019. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5132147.
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Engelbrecht, Sebastian, Kai-Henning Tybussek, Bernd Fischer e Stefan Sommer. "THz- TDS on Polymers: Monitoring Thermo-Oxidative Ageing and Crystallization Kinetics". In 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018). IEEE, 2018. http://dx.doi.org/10.1109/irmmw-thz.2018.8510170.
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Hernandez, Ignacio, Charles Turquand d'Auzay, Richard Penning, Evgeniy Shapiro e John Hughes. "Thermo-Diffusive Flame Speed Adjustment and its Application to Hydrogen Engines". In WCX SAE World Congress Experience. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 2023. http://dx.doi.org/10.4271/2023-01-0197.
Abstract (sommario):
<div class="section abstract"><div class="htmlview paragraph">Practical direct injection hydrogen combustion applications typically require operating the engine in the lean regime. Lean hydrogen flames feature strong thermo-diffusive instability effects making 3D CFD simulations challenging. In particular where the calibrated model is required to operate across a range of equivalence ratios without adjustment and provide accurate results on coarse grids necessitated by the run-times of 3D CFD. In this paper we present a 3D CFD study of a Euro VI HD diesel engine converted to operate on hydrogen gas using direct injection. A scaling methodology recently proposed for conversion from constrained to freely propagating flame based on DNS data is implemented. A laminar flame speed tabulation is developed based on the conversion of 1D results obtained from direct kinetics simulations to freely propagating flame expression considering the behaviour of the thermo-diffusive instability for a wide range of pressures, temperatures and equivalence ratios. The resulting approach is applied to model engine operation under a set of fuelling conditions ranging from <i>λ</i> = 2.5 to <i>λ</i> = 3.5 within the framework of a G-equation/RANS combustion model with tabulated kinetics. Discussion of the meshing requirements is also presented. The resulting model is demonstrated to accurately predict the trends in engine performance and correctly capture the flame acceleration driven by thermo-diffusive effects.</div></div>
5
Chen, Wei, Siva Sankar Thanapal, Kalyan Annamalai, Devesh Ranjan, Ben Lawrence e Robert James Ansley. "Kinetics of Pyrolysis of Mesquite Fuel: Comparison of Different Methods". In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-27349.
Abstract (sommario):
Recently Torrefaction processes are used to improve the quality of fuels. Upper limit on torrefaction temperature can be determined using the maximum volatile release method (MVR) in deducing the kinetics of pyrolysis. The single reaction model (SRM), parallel reaction model (PRM also known as distributed reaction model) and three component models (TCM for hemicellulose, cellulose and lignin) of pyrolysis are briefly reviewed. The MVR method uses the maximum volatile release rate conditions for extracting the kinetics of pyrolysis. Thermogravimetric (TGA) and Differential Thermal (DTA) analyses for mesquite biomass were performed in a thermo-gravimetric instrument and particularly the pyrolysis data of the mesquite samples from MVR are compared with those of SRM and PRM. The focus of current paper is on the extraction of kinetics data (activation energies and pre-exponential factors) from various methods: MVR for the SRM (called as SRM-MVR), PRM and SRM-CA and on the comparison of experimental data with model predictions from SRM-MVR, SRM-CA and PRM for mesquite fuel. It was found that the SRM-CA displays the largest error to predict the mass loss, and SRM-MVR generated less error than SRM-CA even though the kinetics data for SRM-MVR were extracted using a single point. The predicted pyrolysis behavior from the PRM exhibits the best agreement for the whole domain of pyrolysis but peak point which is of importance in torrefaction process is not predicted well. Particularly the kinetics data generated with SRM-MVR is useful in estimating the upper limit on temperature of torrefaction for biomass fuels.
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Wu, Bei, Ronghui Ma e Hui Zhang. "Design and Optimization of an Aluminum Nitride Sublimation Growth System". In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-41980.
Abstract (sommario):
In this paper, an integrated model considering induction heating, heat transfer, growth kinetics and thermo-elastic stress has been developed to study temperature distribution in the growth system, crystal shape and stress distribution in the asgrown aluminum nitride (AIN) crystal. The electromagnetic field and induction heat generation are calculated by the Maxwell equations. Transient temperature distribution in the growth chamber is simulated by energy accounting for conduction/radiation within and between various components. To reduce thermal stress and dislocation, a growth method to enlarge the ingot diameter from a smaller seed and maintain low thermal stress in the crystal has been proposed. The thermo-elastic stress fields have been calculated for several designed temperature profiles along the crucible inner wall and stress distribution has been correlated to dislocation density distribution.
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Yang, X. B., G. H. Su e S. Z. Qiu. "Development of Simulation Codes for Some Accidents in Pressurized Water Reactors". In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48644.
Abstract (sommario):
An analysis code has been developed for evaluating the transient thermo-hydraulic behaviors of the pressurized water reactor system. A series of mathematical and physical models is considered in this code, such as the point reactor neutron kinetics model, the heat transfer model, the friction model, the thermo-physical property model and so on. All possible flow and heat transfer conditions in some accidents have been considered and their corresponding models are supplied. Gear’s method is adopted for a better solution to the stiff equations. In this paper, some general accidents in the pressurized water reactors have been investigated, including the station blackout accident (SBO), the loss of flow accident (LOFA), the loss of feed water accident (LOFWA) and the reactivity insertion accident (RIA). The calculated results have been verified by the RELAP5/Mod3 and the results are satisfactory.
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Hedayat Mofidi, Seyyed Ali, e Kent S. Udell. "Study of Heat and Mass Transfer in MgCl2/NH3 Thermo-Chemical Batteries". In ASME 2016 10th International Conference on Energy Sustainability collocated with the ASME 2016 Power Conference and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/es2016-59099.
Abstract (sommario):
Intermittency of sustainable energy or waste heat availability calls for energy storage systems such as thermal batteries. Thermo-chemical batteries are particularly appealing for energy storage applications due to their high energy densities and ability to store thermal energy as chemical energy for long periods of time without any energy loss. Thermo-chemical batteries based on a reversible solid-gas (MgCl2 - NH3) reactions and NH3 liquid-gas phase change are of specific interest since the kinetics of absorption are fast and the heat transfer rates for liquid — vapor phase change are high. Thus, a thermo-chemical battery based on reversible reaction between magnesium chloride and ammonia was studied. Experimental studies were conducted on a reactor in which temperature profiles within the solid matrix and pressure and flow rates of gas were obtained during charging processes. A numerical model based on heat and mass transfer within the salt and salt-gas reactions was developed to simulate the absorption processes within the solid matrix and the results were compared with experimental data. The studies were used to determine dominant heat and mass transfer processes within the salt. It is shown that for high permeability materials, heat transfer is the dominant factor in determining reaction rates. However increasing thermal conductivity might decrease permeability and reduce reaction rates. The effect of constraining mass flow rate on the temperature and reaction propagation is also studied. These results show that optimized heat and mass transfer within the solid-gas reactor will lead to improved performance for heating and air conditioning applications.
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Saravanan, V., Arun Aravind, Sreenivas Jayanti e Ramakrishna. "Burning Profile of High Ash Indian Coals in Oxy-Fuel Environment". In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67185.
Abstract (sommario):
Oxy-fuel combustion is one of the emerging technologies to capture and store CO2 emissions generated from thermal power plants. Research programs are in full swing to find out the possibility of retrofitting existing coal fired power plants with oxy-fuel mode combustion. Most of the Indian thermal power plants are pulverized coal based and use sub-bituminous Indian coals. These coals differ from the foreign coals in respect of maceral composition, ash content and combustion kinetics. It is imperative to understand the burning characteristics of Indian coals in oxy-fuel environment to evolve the suitable design for the retrofit of Indian boilers with oxy-fuel mode for the efficient and economic carbon capture without losing thermal efficiency. The present study involves the assessment of the kinetics of pyrolysis and char oxidation of three different Indian coals with varying ash contents viz. 33 to 44% in normal air and in oxy-fuel environment with three different CO2/O2 concentrations (60:40, 70:30 and 80:20) by Thermo Gravimetric method (TGA). The results are compared in respect of weight loss pattern, peaking temperatures and weighted mean activation energy. The results have shown that the combustion kinetics of the selected high ash Indian coals in normal air combustion is more comparable with 70:30 and 80:20 than 60:40 CO2/O2 concentrations. The methodology adopted in the present study is found useful for comparing the combustion kinetics of various types of coals in normal air and oxy-fuel environment.
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Hung, Ming-Tsung, e Y. Sungtaek Ju. "Exploration of Thermolithography for Micro- and Nano-Manufacturing". In ASME 2005 Pacific Rim Technical Conference and Exhibition on Integration and Packaging of MEMS, NEMS, and Electronic Systems collocated with the ASME 2005 Heat Transfer Summer Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ipack2005-73424.
Abstract (sommario):
Lithography is a critical enabling technology for manufacturing micro- and nano-scale devices and structures. The manuscript presents our recent progress in the exploration of a new lithography technique that employs localized heating to induce thermo-chemical crosslinking of photoresist layers. The thermal transport properties of photoresist layers are measured and kinetics of cross-linking reactions is studied using microfabricated heaters as localized heat sources. It is demonstrated that polymer films can be patterned in a controlled manner using heater temperature, heating duration, as well as UV exposure dose as control variables. The data and experimental approaches presented here will help systematic evaluation and development of thermolithography schemes.