Letteratura scientifica selezionata sul tema "Fraction de gaz"
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Articoli di riviste sul tema "Fraction de gaz":
1
Serbout, Sanae, Laurent Maxit e Frédéric Michel. "Vibration of a stiffened pipe filled with a bubbly liquid: analysis of resonance frequencies in function of bubble fraction". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, n. 5 (1 agosto 2021): 1008–18. http://dx.doi.org/10.3397/in-2021-1730.
Abstract (sommario):
The characterization of the presence of bubbles in industrial fluid circuits may be extremely important for many safety issuses. It is well known that the acoustic properties of liquids can be drastically modified by a small amount of gaz content in the liquid. At sufficiently low frequencies, the speed of sound depends primarily on the gas volume fraction. The variation of the gas fraction may then induce some variations in the vibroacoustic behavior of the pipe transporting the liquid. Analysis of the pipe vibrations can then help in the monitoring of the bubble presence. In such a context, the aim of this study is to show how the the presence of bubbles in the liquid could affect the resonance frequencies of the pipe. A numerical vibroacoustical model has been developed to predict the vibroacoustical behavior of a stiffened cylindrical shell filled with a bubbly liquid exhibiting low frequency resonances. The model, experimentally verified with a well-characterized bubbly liquid, is then used to analyse the frequency shifts of the shell resonances in function of the bubble. Keywords : pipe, heavy fluid, numerical modelling, circumferential admittance approach, cylindrical shell, resonance frequency, void fraction
2
Quénet, E., G. Weil e V. Billard. "Optimisation de l’administration des agents anesthésiques inhalés : débit de gaz frais ou fraction délivrée ?" Annales Françaises d'Anesthésie et de Réanimation 27, n. 11 (novembre 2008): 900–908. http://dx.doi.org/10.1016/j.annfar.2008.07.097.
3
Jaussaud, Jérémie, Pierre Blanc, Pierre Bordachar, Raymond Roudaut e Hervé Douard. "Response to Cardiac Resynchronization Therapy: The Muscular Metabolic Pathway". Cardiology Research and Practice 2011 (2011): 1–5. http://dx.doi.org/10.4061/2011/830279.
Abstract (sommario):
Background. Changes in peripheral muscle in heart failure lead to a shift from aerobic to early anaerobic metabolism during exercise leading to ergoreflex overactivation and exaggerated hyperventilation evaluated by the VE/VCO2slope.Methods. 50 patients (38 males, years) performed cardio-pulmonary exercise test with gaz exchange measurement and echocardiographic evaluation before and 6 months after CRT.Results. The peak respiratory exchange (VCO2/ VO2) ratio was significantly reduced from to () and the time to the anaerobic threshold was increased from to seconds (). Peak VO2, VE/VCO2, peak circulatory power and NYHA were improved after CRT ( to ml/kg/min (), to (), to mmHg.ml/kg/min () and to ()). In addition, left ventricular ejection fraction and end-systolic volumes were improved from to % () and from to ml ().Conclusion. We suggest that CRT leads to an increase in oxidative muscular metabolism and postponed anaerobic threshold reducing exaggerated hyperventilation during exercise.
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Traore, S., S. Ouedraogo-Kone, A. Samake, M. D. Traore e K. Bengaly. "Effet de l’association entre le tourteau de coton et les gousses de Piliostigma reticulatum (dc) Hochst sur l’ingestion et la digestibilité de la paille de riz". International Journal of Biological and Chemical Sciences 16, n. 3 (27 agosto 2022): 1071–83. http://dx.doi.org/10.4314/ijbcs.v16i3.14.
Abstract (sommario):
L’effet associatif entre les constituants d’une ration peut induire un effet positif ou negative sur les performances de production des ruminants,en function de la nature des constituants de la ration. De plus, La prediction de la valeur alimentaire de la ration sur la base de la somme des valeurs des constituants comporte beaucoup de limites. Deux essais ont été conduits pour évaluer l’effet associatif entre du tourteau de graine de coton non décortiquée (TBM) et les gousses de Piliostigma reticulatum (GP) sur l’ingestion volontaire (essai 1) et la fermentation in vitro à l’aide de la technique du gaz test (essai 2) de la paille de riz seule (PS) ou avec la mélasse et l’urée (PMU). Le TBM a été ajouté à PS ou à PMU dans la proportion: 70 / 30 (PS/TBM ou PMU / TBM). Les GP ont été ensuite substituées au TBM dans la proportion de 15%. Quatre rations ont été formulées pour l’essai 1: R1 (70% PS + 30% TBM), R2 (70% PMU + 30% TBM), R3 (70% PMU + 15% TBM + 15% GP) et R4 = R3 mais TBM et GP ont été distribués de façon séquentielle. Deux autres rations: 100% PS et 100% PMU en plus des rations précédentes, ont servi de substrats pour le gaz test. La ration R2 comparée à R1 a significativement (p < 0.05) amélioré les performances de croissance des taurillons. Par contre, l’apport de GP n’a pas eu d’effet car les GP n’ont pas été consommées tout au long de l’essai. Contrairement aux traitements PS et TBM (essai 2), les traitements PMU et TBM ont engendré une augmentation significative (p < 0.05) du taux horaire (c) de fermentation de la fraction insoluble (b), la concentration des acides gras volatiles (AGV) et la production de gaz à 12, 24, 36 et 48 h. L’interaction entre PMU, TBM et GP a été positive et significative. L’apport de la mélasse-urée en plus du tourteau et les gousses de Piliostigma a permis d’améliorer la valeur nutritive de la paille de riz.
The associative effect between the constituents of a ration can positively or negatively affect ruminant animals ‘performances, depending on the nature of the constituents of the ration. Moreover, predicting the feeding value of the ration by simply adding the individual feed value of the constituents has some limitations. Two trials were conducted to assess the associative effect between unhulled cottonseed meal (TBM) and Piliostigma reticulatum pods (GP) on voluntary intake (trial 1) and in vitro fermentation using the gas production technique (trial 2) of rice straw alone (PS) or PS with molasses and urea (PMU). TBM was added to PS or PMU in the proportion: 70/30 (PS/TBM or PMU/TBM). The GPs were then substituted for the TBM in the proportion of 15%. Four rations were formulated for trial 1: R1 (70% PS + 30% TBM), R2 (70% PMU + 30% TBM), R3 (70% PMU + 15% TBM + 15% GP) and R4 = R3 but TBM and GP distributed sequentially. Two other rations: 100% PS and 100% PMU in addition to the previous rations, served as substrates for the gas test. The R2 ration compared to R1 significantly (p < 0.05) improved the growth performance of the young bulls. On the other hand, the supply of GP had no effect because the GP were not consumed throughout the trial. Unlike the PS and TBM treatments (trial 2), the PMU and TBM treatments generated a significant increase (p < 0.05) in the hourly rate (c) of fermentation of the insoluble fraction (b), the concentration of volatile fatty acids (VFAs) and gas production at 12, 24, 36 and 48 h. The interaction between PMU, TBM and GP was positive and significant. The supply of molasses and urea in addition to cottonseed cake and Piliostigma pods improved the nutritional value of rice straw.
5
Do, Dinh Nhat, Dinh Phuc Nguyen, Viet-Duc Phung, Xuan-Tien Le, Tuan Minh Le, Van Manh Do, Bui Quang Minh e Xuan Cuong Luu. "Fractionating of Lemongrass (Cymbopogon citratus) Essential Oil by Vacuum Fractional Distillation". Processes 9, n. 4 (29 marzo 2021): 593. http://dx.doi.org/10.3390/pr9040593.
Abstract (sommario):
Lemongrass essential oil has many compounds appropriate for application in foods, cosmetics, and pharmaceutical products. Of these, citral is a high-value compound of interest to industry. This work aims to evaluate the use of vacuum fractional distillation to separate lemongrass essential oil compounds, producing essential oil fractions containing high citral content. The effect of process parameters, namely vacuum pressure, type column, and energy input, on the fractionation time, content, and recovery of citral in the fractions, was investigated. The fractionation of lemongrass oils successfully provided five fractions, i.e., fraction 1 (F1), fraction 2 (F2), fraction 3 (F3), fraction 4 (F4), and fraction 5 (F5). GC-MS (Gas Chromatography-Mass Spectrometry) spectra showed that the main compound contained in F1 and F2 fractions was β-myrcene (>70%). Meanwhile, F4 and F5 were the two main fractions for citral recovery. The optimal conditions of the fractional distillation system included a column height of 400 mm, power input of 165 W, and pressure of 15 mmHg. These conditions correspond to the highest total citral content of 95%, with a recovery of 80% at the F4 and F5 fractions. Therefore, fractional vacuum distillation may be an effective method to upgrade lemongrass essential oil.
6
Deng, Min, Pavlos Kollias, Zhe Feng, Chidong Zhang, Charles N. Long, Heike Kalesse, Arunchandra Chandra, Vickal V. Kumar e Alain Protat. "Stratiform and Convective Precipitation Observed by Multiple Radars during the DYNAMO/AMIE Experiment". Journal of Applied Meteorology and Climatology 53, n. 11 (novembre 2014): 2503–23. http://dx.doi.org/10.1175/jamc-d-13-0311.1.
Abstract (sommario):
AbstractIn this study, methods of convective/stratiform precipitation classification and surface rain-rate estimation based on the Atmospheric Radiation Measurement Program (ARM) cloud radar measurements were developed and evaluated. Simultaneous and collocated observations of the Ka-band ARM zenith radar (KAZR), two scanning precipitation radars [NCAR S-band/Ka-band Dual Polarization, Dual Wavelength Doppler Radar (S-PolKa) and Texas A&M University Shared Mobile Atmospheric Research and Teaching Radar (SMART-R)], and surface precipitation during the Dynamics of the Madden–Julian Oscillation/ARM MJO Investigation Experiment (DYNAMO/AMIE) field campaign were used. The motivation of this study is to apply the unique long-term ARM cloud radar observations without accompanying precipitation radars to the study of cloud life cycle and precipitation features under different weather and climate regimes. The resulting convective/stratiform classification from KAZR was evaluated against precipitation radars. Precipitation occurrence and classified convective/stratiform rain fractions from KAZR compared favorably to the collocated SMART-R and S-PolKa observations. Both KAZR and S-PolKa radars observed about 5% precipitation occurrence. The convective (stratiform) precipitation fraction is about 18% (82%). Collocated disdrometer observations of two days showed an increased number concentration of small and large raindrops in convective rain relative to dominant small raindrops in stratiform rain. The composite distributions of KAZR reflectivity and Doppler velocity also showed distinct structures for convective and stratiform rain. These evidences indicate that the method produces physically consistent results for the two types of rain. A new KAZR-based, two-parameter [the gradient of accumulative radar reflectivity Ze (GAZ) below 1 km and near-surface Ze] rain-rate estimation procedure was developed for both convective and stratiform rain. This estimate was compared with the exponential Z–R (reflectivity–rain rate) relation. The relative difference between the estimated and surface-measured rainfall rates showed that the two-parameter relation can improve rainfall estimation relative to the Z–R relation.
7
Rieger, Tobias, Jessen C. Oey, Volodymyr Palchyk, Alexander Hofmann, Matthias Franke e Andreas Hornung. "Chemical Recycling of WEEE Plastics—Production of High Purity Monocyclic Aromatic Chemicals". Processes 9, n. 3 (16 marzo 2021): 530. http://dx.doi.org/10.3390/pr9030530.
Abstract (sommario):
More than 200 kg real waste electrical and electronic equipment (WEEE) shredder residues from a German dismantling plant were treated at 650 °C in a demonstration scale thermochemical conversion plant. The focus within this work was the generation, purification, and analysis of pyrolysis oil. Subsequent filtration and fractional distillation were combined to yield basic chemicals in high purity. By means of fractional distillation, pure monocyclic aromatic fractions containing benzene, toluene, ethylbenzene, and xylene (BTEX aromatics) as well as styrene and α-methyl styrene were isolated for chemical recycling. Mass balances were determined, and gas chromatography–mass spectrometry (GC-MS) as well as energy dispersive X-ray fluorescence (EDXRF) measurements provided data on the purity and halogen content of each fraction. This work shows that thermochemical conversion and the subsequent refining by fractional distillation is capable of recycling WEEE shredder residues, producing pure BTEX and other monocyclic aromatic fractions. A significant decrease of halogen content (up to 99%) was achieved with the applied methods.
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Krishnamoorthy, Gautham, Rydell Klosterman e Dylan Shallbetter. "A Radiative Transfer Modeling Methodology in Gas-Liquid Multiphase Flow Simulations". Journal of Engineering 2014 (2014): 1–14. http://dx.doi.org/10.1155/2014/793238.
Abstract (sommario):
A methodology for performing radiative transfer calculations in computational fluid dynamic simulations of gas-liquid multiphase flows is presented. By considering an externally irradiated bubble column photoreactor as our model system, the bubble scattering coefficients were determined through add-on functions by employing as inputs the bubble volume fractions, number densities, and the fractional contribution of each bubble size to the bubble volume from four different multiphase modeling options. The scattering coefficient profiles resulting from the models were significantly different from one another and aligned closely with their predicted gas-phase volume fraction distributions. The impacts of the multiphase modeling option, initial bubble diameter, and gas flow rates on the radiation distribution patterns within the reactor were also examined. An increase in air inlet velocities resulted in an increase in the fraction of larger sized bubbles and their contribution to the scattering coefficient. However, the initial bubble sizes were found to have the strongest impact on the radiation field.
9
Yeh, Chun-Lang. "Numerical study of the burner parameters on the thermal field in a sulfur recovery unit thermal reactor". MATEC Web of Conferences 169 (2018): 01013. http://dx.doi.org/10.1051/matecconf/201816901013.
Abstract (sommario):
A sulfur recovery unit (SRU) thermal reactor is the most important equipment in a sulfur plant and is negatively affected by high temperature operations. In this paper, the effect of burner parameters, including the clearance of the acid gas tip and the inlet air swirler angle, on the thermal field in a SRU thermal reactor are investigated numerically, with the aim to reduce the high temperature inside the thermal reactor and to ensure an acceptable sulfur recovery. The simulation results show that the burner with a smaller clearance of the acid gas tip produces a lower temperature, a lower exit SO2 mole fraction and higher exit S2 and H2S mole fractions. Among the clearancs of the acid gas tip investigated, the horizontal clearance of 152.4mm and vertical clearance of 240mm yield the lowest temperature, exit SO2 mole fraction and highest exit S2, H2S mole fractions. The burner with a smaller inlet air swirler angle produces a higher temperature, a higher exit SO2 mole fraction and lower exit S2 and H2S mole fractions. Among the swirler angles investigated, 60° yields the lowest temperature, exit SO2 mole fraction and highest exit S2 , H2S mole fractions.
10
Sumi Lestari, Fajar, Ricson Pemimpin Hutagaol e Srikandi Srikandi. "Crystal guava (Psidium guajava L. “Crystal”) treated with gibberelic acid (GA3) : Evaluation of in vitro antioxidant capacities". Jurnal Pendidikan Kimia 15, n. 2 (30 agosto 2023): 82–90. http://dx.doi.org/10.24114/jpkim.v15i2.41780.
Abstract (sommario):
Free radicals can cause many diseases, such as cancer. Antioxidant is a compound that could scavenge free radicals. One of the natural source antioxidants is guava. The application of gibberellic acid (GA3) is known to affect the physicochemical properties and antioxidant content of the fruit. The goals of this research were to investigate the antioxidant activity of skin, flesh and fruit of crystal guava were given additional GA3 treatment with concentration 0; 60; 120; 180; 240; and 300 ppm by determining the value of the Antioxidant Activity Index (AAI) using DPPH; evaluate the total phenolic content (TPC), ferric reducing antioxidant power (FRAP) and physicochemical properties; analyse the correlation between the TPC with AAI DPPH by Pearson’s method. Extraction was performed by the maceration method using acetone 50% mixed with a magnetic stirrer for 1 h. Determination of AAI DPPH, FRAP and the TPC was performed by UV-Visible spectrophotometry. TPC in the flesh and fruit fractions tended to increase and FRAP values in all fractions decreased with GA3 application. The highest TPC and FRAP was given by the G3 treatment on the skin fraction and G0 treatment on the skin fraction. The highest AAI in all fractions was given by the G3 treatment. The TPC was significantly positively correlated with the AAI DPPH of the flesh and fruit fraction extracts (0.250 ≤ r ≤ 0.880), and the skin fraction extracts showed a strong negative correlation between TPC and AAI DPPH (-0.813 < r < -0.973).
Tesi sul tema "Fraction de gaz":
1
Jannoun, Pascal. "Caractérisation expérimentale et modélisation 0D/1D de la quantité de gaz résiduels dans un moteur à allumage commandé". Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0010/document.
Abstract (sommario):
La quantité de gaz résiduels présents dans le cylindre d’un moteur à combustion interne a une influence important sur son fonctionnement (combustion, rendement, émissions,..) particulièrement en allumage commandé. Aujourd’hui, il est possible de modifier cette quantité, notamment grâce à des systèmes de distribution variable. Cependant, la détermination expérimentale de la quantité de résiduels et l’estimation à partir de modèles numériques restent délicates. L’objectif de cette thèse est de proposer de nouvelles méthodologies pour traiter ces deux problématiques. Un point bibliographique est tout d’abord effectué pour dresser un état de l’art. Il recense les principaux paramètres influençant la quantité de résiduels, les effets des résiduels sur le fonctionnement du moteur, les moyens expérimentaux et les modèles disponibles pour en évaluer la quantité. Un système original est ensuite développé pour mesurer la quantité de résiduels à partir d’un prélèvement gazeux effectué dans le cylindre à la fin de la compression. Les résultats ainsi obtenus sur l’ensemble du champ de fonctionnement d’un moteur automobile atmosphérique à allumage commandé sont ensuite analysés en fonction du régime, de la charge et de la position du déphaseur installé sur l’arbre à came d’admission. Enfin, plusieurs modélisations de la phase de croisement des soupapes en approche 0D/1D sont évaluées. L’approche classique de mélange parfait n’étant pas satisfaisante, de nouvelles approches originales sont proposée et testées. Une approche hybride mêlant mélange parfait et déplacement parfait permet d’obtenir des résultats améliorés, après calibration d’un paramètre en fonction du régime et de la charge du moteurThe amount of residual gas trapped in the cylinder of an internal combustion engine has a huge influence on its behavior (combustion, efficiency, emission,..), in particular for spark ignition engines. Nowadays, it is possible to modify this amount, in particular with variable valve train. However, the experimental assessment of residual gas content and its evaluation with numerical simulation are still challenging. The objective of this study is to propose new methodologies to improve these two aspects. A bibliographical survey is first proposed to give state of the art. It gathers the main parameters influencing residual gas content, the effects of residual gas on engine behavior, experimental procedures and numerical models available for residual gas content estimation. An original system is then developed to measure the amount of residual gas with an in-cylinder gas sampling triggered at the end of compression stroke. The results, obtained on the whole operating map of a naturally aspirated automotive spark ignition engine, are analyzed with respect to engine rotation speed, load and cam phaser position (intake side). Finally, various modeling of valve overlap with a 0D/1D approach are assessed. The standard “perfect mixing” assumption is not fully satisfactory, so that new assumptions are proposed and tested. A hybrid approach combining “perfect mixing” and “perfect displacement” allows for improved agreement with experiments, after calibration of a model parameter with respect to engine rotation speed and load
2
Sportisse, RoyetT Myriam. "Modélisation des propriétés thermodynamiques des gaz à condensat : par représentation de la fraction lourde à l'aide de fonctions de distribution". Aix-Marseille 2, 1996. http://www.theses.fr/1996AIX22076.
Abstract (sommario):
Si, a l'heure actuelle, nous sommes capables de simuler de maniere quasi-predictive le comportement des huiles, aucune methode vraiment satisfaisante n'a encore ete developpee pour predire les proprietes des gaz a condensat. Pour ce type de fluides, l'ajustement des modeles thermodynamiques reste incontournable. Nous proposons une strategie d'ajustement basee sur la representation de la fraction lourde des gaz a condensat par des fonctions de distributions des trois familles chimiques suivantes: paraffines, monoaromatiques, polyaromatiques. Le probleme se ramene alors a la determination des parametres definissant ces fonctions afin de minimiser l'erreur sur la courbe de depot liquide a masse constante, que l'on obtient indirectement apres un certain nombre de calculs d'equilibre, couteux en temps calcul. Du fait de l'existence de nombreux minima locaux sur la fonction d'erreur a minimiser, un algorithme d'optimisation des parametres fonde sur une methode du simplex de nelder-mead couplee a une procedure de recuit simule a ete utilise. Les calculs des proprietes pvt sont effectues a partir de l'equation d'etat de peng-robinson (1978). Pour les polyaromatiques, des correlations simples pour la determination des proprietes des corps purs ont ete developpees, les correlations proposees par rogalski et neau (1990) etant utilisees pour les n-alcanes et les monoaromatiques. De bons resultats ont ete obtenus sur plus de 20 gaz a condensat d'origines geographiques diverses. De plus, notre methode predit les masses volumiques du liquide de stockage et de la fraction lourde avec une erreur moyenne de 1,2% et 3,6%. Les resultats satisfaisants pour les tests d'extrapolation en temperature demontrent la validite de notre methodologie dans un large domaine de pression et de temperature
3
Al-Khazraji, Hayder. "Influence of crack opening, aggregates size and volume fraction on hydro-mechanical properties of concrete in a Brazilian splitting test : 3D meso-macro scale modeling and experimental work". Thesis, Nantes, 2017. http://www.theses.fr/2017NANT4106/document.
Abstract (sommario):
La perméabilité influe indirectement sur la durabilité des structures en béton. Elle gouverne le taux de pénétration des agents agressifs, responsables de dégradations, sous un gradient de pression. Ce travail a pour but l’étude des interactions entre l’ouverture des fissures et le transport des fluides dans le béton, soumis à un essai Brésilien de traction indirect par fendage. Cette étude est composée de deux parties : une numérique et une expérimentale. La première concerne la modélisation des matériaux hétérogènes, tels que le béton, et met en évidence ses deux particularités : l’aspect multiphasique du matériau et la propagation 3D de fissures. Ainsi, nous proposons un couplage entre l’ouverture de fissure et la perméabilité au gaz selon un modèle hydromécanique à l’échelle mésoscopique. L’objectif de la deuxième partie expérimentale est de fournir des données pour des modèles numériques et de les valider ainsi. Ce travail est réalisé sur des éprouvettes de mortier avec 3 différents tailles de granulat, soumises au transfert de gaz au cours du chargement par l’essai Brésilien. Le modèle numérique mésoscopique, employé dans cette étude, est basé sur une approche tridimensionnelle pour représenter l’hétérogénéité du matériau et les mécanismes de rupture du béton. Ce modèle considère le béton comme un matériau bi-phasique où les granulats sont fondus dans la pâte du ciment. Afin de pallier aux hétérogénéités du matériau et l’emploi du maillage non-adaptatif, une faible discontinuité a été introduite dans le premier enrichissement de la cinématique. Le deuxième enrichissement de la cinématique introduite ici est la discontinuité du déplacement (forte) afin de représenter l’ouverture de la fissure (champ du déplacement discontinu). Le modèle hydromécanique représente le transport du fluide (gaz) dans le béton par l’intermédiaire de la loi de Darcy pour la section non fissurée (porosité) et par la loi de Poiseuille pour la section fissurée (flux laminaire). Dans ce modèle, une interaction entre l’ouverture de fissure, obtenue par le modèle mécanique (mésoscopique), et la perméabilité du gaz est considérée. Le travail expérimental effectué est présenté pour la validation du modèle hydro-mécanique numérique proposé. Les résultats de simulations numériques sont en accord avec des travaux expérimentaux et théoriques précédentsPermeability is a parameter that may indirectly influence the durability of concrete structures by governing the rate of penetration of aggressive substances responsible for degradation under a pressure gradient. The aim of this thesis is to study the interaction between the crack opening and the transfer of fluids in concrete of the Brazilian splitting tensile test (BSTT). Herein, the influence of aggregates size and volume fraction on hydro-mechanical properties of concrete is investigated. This study consists of two parts: the numerical and the experimental one. The first one focuses on the meso-scale modeling of a heterogeneous material like a concrete, which may be characterized by two features: multi-phase behavior and 3D crack propagation. The numerical study deals therefore with the coupling between crack opening and gas permeability according to a developed hydro-mechanical model at a meso-scale. The objective of the second, experimental part, is to provide data for numerical models and to validate the latter. This work is carried out on mortar specimens with 3 different aggregate sizes, submitted to gas transfer during a BSTT. The numerical meso-scale model is based upon a 3D lattice approach to represent the heterogeneity of the material and the failure mechanism of concrete. This model considers concrete as a two-phases material in which aggregates melt within a cement paste. Because a non-adapted meshing process was used to mesh the microstructure, a weak discontinuity was introduced in the first enhancement of the kinematics. The second enhancement of kinematics introduced here is the displacement discontinuity (strong) to represent crack opening (discontinuous displacement-field). The hydro-mechanical model represents the transport of fluids (gases) through the concrete, depending on Darcy's law for a uncracked section (porosity) and Poiseuille's law for a cracked section (laminar flow). In this model, the interaction between the crack opening, obtained from the mechanical model (meso-scale), and the gas permeability is investigated. The experimental work is presented for the validation of the hydro-mechanical model. The numerical results show good agreement with some previous experimental and theoretical studies
4
Holzmann, Markus. "La transition de Bose-Einstein dans un gaz dilué". Phd thesis, Université Pierre et Marie Curie - Paris VI, 2000. http://tel.archives-ouvertes.fr/tel-00011774.
Abstract (sommario):
Dans cette thèse je présente mes travaux sur la transition de Bose-Einstein dans un gaz dilué, où l'interaction entre les bosons est caractérisée par la longueur de diffusion a. Au début j'étudie la température critique de la condensation dans un gaz homogène. En mettant en oeuvre des approches diverses - analytiques et numériques —, je montre la linéarité en a de la correction dominante à la température critique du gaz parfait. En utilisant une approche perturbative dans un calcul de Monte-Carlo quantique, la valeur de la température critique est obtenue dans la limite d'un gaz très dilué. Ensuite je présente mes calculs de Monte-Carlo quantique adaptés à une situation expérimentale avec N = 10 000 atomes piégés dans un potentiel harmonique. Je détermine la fraction condensée et la fonction d'onde du condensat dans ce système inhomogène, partant du concept de l'ordre non-diagonal à longue portée. La comparaison quantitative du calcul de Monte-Carlo quantique avec des approximations simples montre les limites d'une approximation de champ moyen et permet d'estimer les effets de corrélation dans un gaz piégé.
5
Wicker, Raphaël. "Baryons in galaxy clusters : astrophysical effects and cosmological constraints". Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASP114.
Abstract (sommario):
Les amas de galaxies sont les objets gravitationnellement liés les plus massifs de l'univers, et l'histoire de leur formation est une conséquence directe de l'évolution des structures dans l'univers. Ainsi, leur étude permet de poser des contraintes cosmologiques. L'utilisation des amas en tant que sondes cosmologiques repose sur l'observation de leur contenu en matière, en particulier ordinaire, ou baryons. Ces derniers sont présents sous forme d'étoiles contenues dans les galaxies, et de gaz au sein du milieu intra-amas. Toutefois, les baryons dans les amas de galaxies sont sujets à des effets astrophysiques qui affecteront leurs propriétés. Ces effets doivent être étudiés en détail afin d'obtenir une bonne compréhension des amas et contraindre correctement les conditions ayant dicté leur formation, jusqu'à leurs propriétés actuelles.Je propose ainsi dans cette thèse une étude approfondie des baryons et de leurs effets dans les amas, des galaxies au gaz, à partir d'observations en millimétrique, optique, et rayons X.Une première partie de mon étude se concentre sur les galaxies et l'analyse de leurs propriétés à partir de données de spectroscopie optique, dans deux systèmes triples d'amas découverts par le satellite Planck. Je montre que ces deux systèmes n'apparaissent triples que suite à des effets de projection sur la ligne de visée, et sont en réalité constitués de plusieurs amas isolés se trouvant à plusieurs centaines de megaparsecs les uns des autres, exceptée une paire d'amas.De plus je montre que dans l'amas le plus distant, certaines galaxies forment encore des étoiles, contrairement aux galaxies dans les amas à plus bas redshift. Il est possible que cela marque la transition entre un régime d'intense formation stellaire dans les amas à haut redshift, et le régime de faible formation stellaire observé dans les amas à bas redshift.La suite de mon étude est dédiée à la fraction de gaz au sein des amas, en particulier afin de contraindre le biais découlant de l'hypothèse d'équilibre hydrostatique lors de la mesure de leur masse. Mal contraint, ce "biais hydrostatique", est responsable de contraintes cosmologiques biaisées à partir des amas. En utilisant des masses de gaz et des masses totales mesurées en rayons X sous l'hypothèse de l'équilibre hydrostatique, j'ai calculé la fraction de gaz de 120 amas, et ai étudié la valeur du biais hydrostatique et son évolution avec la masse et le redshift. Je montre que l'évolution du biais est dégénérée avec les paramètres cosmologiques, menant à des contraintes cosmologiques aberrantes en cas de mauvaise prise en compte de l'évolution du biais. Cependant, je montre que mes résultats dépendent de l'échantillon choisi, avec une évolution du biais différente suivant la sélection en masse et en redshift. Je montre toutefois que quelque soit la sélection de l'échantillon, mes résultats sont en accord avec un ensemble de mesures directes par d'autres méthodes, ainsi qu'avec les prédictions de simulations hydrodynamiques. Ces résultats sont néanmoins en désaccord avec la valeur de biais favorisée par des observations du fond diffus cosmologique combinées à des comptages d'amas.Enfin, j'ai combiné des données de fraction de gaz d'amas de galaxies avec des comptages réalisés à partir d'observations en ondes millimétriques. Cela m'a permis d'étudier les contraintes cosmologiques rendues possibles par cette combinaison, ainsi que les contraintes sur le biais hydrostatique. Je montre que l'ajout de données de fraction de gaz aux comptages d'amas permet de briser des dégénérescences existantes entre le biais hydrostatique et certains paramètres cosmologiques, sans a priori sur le biais.Mon travail a donc permis d'améliorer notre compréhension d'ensemble des propriétés astrophysiques des baryons dans les amas. J'ai notamment mis en évidence certains des liens entre effets astrophysiques et contraintes cosmologiques par les amas, permettant leur description fidèle et robusteGalaxy clusters are the most massive gravitationally bound structures of the universe, and the history of their formation is a direct consequence of the evolution of the large scale structure of the universe. As a result, studying these objects allows to constrain cosmological parameters, which are at the core of the models describing the evolution of our universe. The use of galaxy clusters as cosmological probes relies on the observation of their matter content, and in particular their content in ordinary matter, or "baryons". Baryonic matter is mainly present under the form of stars in galaxies and of gas inside the intra-cluster medium. However, baryons in galaxy clusters are subject to astrophysical effects which will impact their properties. These effects need to be analysed in detail in order to obtain an in depth understanding of these objects and to properly constrain the conditions that dictated their formation, their assembly, and their current properties.I propose in this thesis a thorough analysis of baryons and of their effects in clusters, from galaxies to the gas, using observations in optical, X-ray, and millimeter wavelengths. A first part of my study is focused on galaxies and the analysis of their properties from optical spectroscopy, inside two triple-cluster systems discovered by the Planck satellite. I show that these two systems appear as triple only due to projection effects on the line of sight, and that they are actually constituted of isolated clusters lying at several hundreds of megaparsecs from each other, except for a cluster pair. I show in addition that inside the most distant cluster, several galaxies are still star-forming, contrary to the galaxies in lower redshift systems. This may be the sign of a transition between a regime of high star formation in high redshift systems and the low star formation regime which is observed in low redshift clusters.The remainder of my work is dedicated to the gas fraction in galaxy clusters, in particular to constrain the bias which appears following the assumption of hydrostatic equilibrium when measuring cluster masses. This "hydrostatic bias", if poorly understood, is responsible for biased cosmological constraints from galaxy clusters. By using gas masses and total masses computed under the assumption of hydrostatic equilibrium in X-ray observations, I computed the gas fraction of 120 galaxy clusters, and constrained the value of the hydrostatic bias, as well as its evolution with mass and redshift. I show that the evolution of the bias is degenerate with cosmological parameters, leading to aberrant cosmological constraints when assuming the wrong evolution for the bias. I however show that these results are dependent on the considered sample, with trends of the bias changing depending on the mass and redshift selection of the sample. In any case, whatever the sample selection I find that my results are in agreement with a collection of other measurements of the bias using other methods, as well as with predictions from hydrodynamical simulations. These results are nevertheless in tension with the value of the bias preferred by the combination of cosmic microwave background observations with galaxy cluster number counts.Finally I combined gas fraction data of clusters with cluster number counts from millimeter wavelengths observations. This allowed me to study the constraints on cosmological parameters that this combination allowed, as well as the constraints on the hydrostatic bias. I show that adding gas fraction to cluster counts allows to break degeneracies that exist between the hydrostatic bias and cosmological parameters, without any prior on the bias.My work thus allowed to improve the understanding of the astrophysical properties of baryons in galaxy clusters. I notably highlighted some of the links and correlations between astrophysical effects and cluster cosmology, allowing for an accurate and robust description of these objects
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Durecu, Sylvain. "Biométhanisation des déchets d'élevage : approche de la solubilisation de la fraction solide et valorisation de sous-produits". Nancy 1, 1989. http://www.theses.fr/1989NAN10304.
Abstract (sommario):
Afin d'améliorer les performances de la digestion mésophile du lisier de porc au temps de rétention défini de 10 jours, la solubilisation de la fraction solide, étape limitante de la biométhanisation, a été étudiée en digesteurs expérimentaux infiniment mélangésTo improve the performances of the mésophile digestion of pork's(pig) liquid manure in the time of retention defined of 10 days, the solubilization of the solid fraction, the limitante stage of the biomethanation, was studied experimental infinitely mixed digesteurs there
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Cenker, Emre. "Imaging measurements of soot particle size and soot volume fraction with laser-induced incandescence at Diesel engine conditions". Thesis, Châtenay-Malabry, Ecole centrale de Paris, 2014. http://www.theses.fr/2014ECAP0049/document.
Abstract (sommario):
Le travail présenté dans ce manuscrit concerne les mesures de taille de particule et de fraction volumique de suies dans des conditions moteur Diesel. Les techniques utilisées sont la laser-Induced incandescence (LII), la méthode d’extinction laser (LEM), la pyrométrie, et l’analyse d’images de microscopie électronique par transmission (TEM) d’échantillons prélevés in-Situ. Des stratégies de mesure de tailles de particules sont développées en se basant sur l’utilisation d’un modèle LII et en analysant la poly-Dispersion des tailles de particules, aussi bien à partir de signaux de LII résolu en temps (mesures ponctuelles) à pression atmosphérique, que d’informations résolues spatialement provenant d’images acquises a deux instants différents. Des mesures sont effectuées avec ces stratégies sur une flamme à pression atmosphérique et dans des conditions représentatives des conditions moteur Diesel pour évaluer leur applicabilité. Des mesures supplémentaires de température et de fraction volumique de suies sont aussi réalisés.Une nouvelle méthode, appelée two-Exponential reverse fitting (TERF) est introduite. Elle vise à extraire des informations sur la distribution de tailles de particules. Cette méthode est basée sur l’utilisation de fits mono-Exponentiel du signal de décroissance de LII à différents intervalles de temps. La distribution de tailles de particules est approximée par la combinaison de deux distributions de tailles de particules mono-Disperses : une petite et une large. Aucune hypothèse sur la forme de la distribution n’est nécessaire. La méthode permet aussi de fournir le ratio de la proportion respective des deux classes de particules. L’erreur systématique induite par la description mono-Exponentielle de la décroissance du signal de LII a été calculée et est inférieure à 2% pour des décroissances de signal de LII d’aggregats mono-Disperses avec des températures de chauffe pour lesquels la sublimation des suies est négligeable. La méthode a été appliquée à des données de LII obtenus sur une flamme laminaire atmosphérique éthylene/air à différentes hauteurs. Les résultats obtenus montrent un bon accord entre les tailles des grosses particules évaluées avec la méthode TERF et celle obtenue par analyse des images TEM. En revanche l’accord n’est pas obtenu pour les petites particules, ce qui est attribué à un manque d’information sur cette classe de particule dans l’analyse TEM.Des champs de fraction volumique de suies sont ensuite obtenus dans une cellule haute pression haute température dans les conditions opératoires du réseau ECN (Engine Combustion Network) par technique combinée de LEM et LII simultanées. Les mesures sont réalisées dans les conditions du spray A et incluent des variations paramétriques (température et dilution). La distance de Lift Off de la flamme est déterminée en parallèle par visualisation directe de la chimiluminescence OH. Des niveaux de fraction volumique maximale de 2-3ppm sont obtenus dans les conditions nominales du spray A (i.e. 900K), et peuvent atteindre 12 pmm à haute température (1030K). L’effet des variations de température et de concentration d’oxygène sur la formation et l’oxydation des suies et cohérente avec les résultats issus de la littérature.Une méthode d’imagerie de taille de particules est développée. Elle est basée sur l’acquisition de deux images de LII obtenues à deux instants différents après le pulse laser et l’analyse de ces images à l’aide de la simulation du signal LII pour déduire les tailles des particules à partir du rapport des images. Une stratégie basée sur une analyse par modèle LII est développée pour évaluer les incertitudes de mesure. La dépendance aux conditions limites de l’imagerie de taille de particule par LII est ainsi évaluée. [...]This work focuses on measurements of soot particle size and volume fraction at Diesel engine conditions. A combination of laser-Induced incandescence (LII) imaging, line-Of-Sight laser extinction, soot pyrometry, and transmission electron microscopy (TEM) measurements of thermophoretically-Sampled soot was used. Particle sizing strategies were developed with LII model for the analysis of particle-Size poly-Dispersity with time-Resolved LII signal that is suitable for point-Wise measurements at atmospheric pressure, and for spatially-Resolved characterization with two-Time-Step LII imaging. Measurements were performed with these strategies in a flame at atmospheric pressure and in Diesel engine combustion to investigate their applicability. Additional measurements were performed for temperature and soot volume fraction.A novel method, called two-Exponential reverse fitting (TERF), is introduced to extract information about the size distribution. The method is based on mono-Exponential fits to the LII signal decay at a delayed time. It approximates the particle-Size distribution as a combination of one large and one small mono-Disperse equivalent mean particle size and does not require a distribution assumption. It also provides a ratio of the contribution of both size classes. The systematic error caused by de-Scribing LII signals by mono-Exponential decays was calculated as less than 2% for LII signals simulated for mono-Disperse aggregated soot with heat-Up temperatures for which evaporation is negligible. The method was applied to LII data acquired in a laminar non-Premixed ethylene/air flame at various heights above the burner. The particle size of the large particle-Size class evaluated with the method showed good consistency with TEM results, however the size of the small particle-Size class and its relative contribution could not be compared due to insufficient information in the TEM results for small particles. Simultaneous line-Of-Sight laser extinction measurements and LII imaging were performed to de-Rive the soot volume fraction in a high-Temperature high-Pressure constant-Volume pre-Combustion vessel under the Engine Combustion Network’s (ECN) "Spray A" conditions with parametric variations of gas temperature and composition. Extinction measurements were used to calibrate LII images for quantitative soot distribution measurements. OH-Chemiluminescence imaging was used to determine the lift-Off length, and used to interpret the soot measurements. Maximum soot volume fractions around 2–3 ppm were obtained at the nominal ambient temperature defined for Spray A (i.e. 900 K) that rise to 12 ppm at elevated temperature (1030 K). Variations of ambient temperature and oxygen concentration were carried out showing effects on soot formation and oxidation that are consistent with the literature.The method for particle-Size imaging is based on evaluating gated LII signals acquired with two cameras consecutively after the laser pulse and using LII modeling to deduce particle size from the ratio of local signals. A strategy was developed with a model-Based analysis: the dependence of LII particle-Size imaging on the assumed boundary conditions was identified such as bathgas temperature, pressure, particle heat-Up temperature, thermal accommodation coefficients, and soot morphology. Various laser-Fluence regimes and gas pressures were considered. Effects of laser attenuation were evaluated. A combination of one detection gate starting with the particle-Heating and the other starting with 11 ns delay with twice as long gate width was found to provide the highest sensitivity for particle sizing at 60 bar. The optimum gate delays for different pressures were calculated. The effects of timing jitter for laser pulse and poly-Dispersity were investigated. Systematic errors in pyrometry imaging at 60 bar was evaluated. [...]
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Mendes, Melchuna Aline. "Experimental study and modeling of methane hydrates cristallization under flow from emulsions with variable fraction of water and anti-agglomerant". Thesis, Lyon, 2016. http://www.theses.fr/2016EMSE0811/document.
Abstract (sommario):
La cristallisation des hydrates pendant la production de pétrole est une source de risques, surtout liés au bouchage des lignes de production dû à l’agglomération des hydrates. Pendant l'extraction de pétrole, l'huile et l'eau circulent dans le pipeline et forment une émulsion instable. La phase eau se combine avec les composants d'hydrocarbures légers et peut former des hydrates. La cristallisation des hydrates a été intensivement étudiée, principalement à faible fraction d’eau. Cependant, lorsque le champ de pétrole devient mature, la fraction d’eau augmente et peut devenir la phase dominante, un système peu étudié concernant à la formation d'hydrates. Plusieurs techniques peuvent être combinées pour éviter ou remédier la formation d'hydrates. Récemment, une nouvelle classe d'additifs a commencé à être étudiée : Inhibiteurs d'Hydrates à Bas Dosage (LDHI), divisés en Inhibiteurs Cinétiques (KHI-LDHI) et anti-agglomérants (AA-LDHI).Ce travail est une étude paramétrique de la formation d'hydrates à partir de l'émulsion, en variant la fraction d’eau, le débit, en absence et en présence d’AA-LDHI. Les expériences ont été réalisées sur la boucle d'écoulement Archimède, qui est en mesure de reproduire les conditions de la mer profonde. L'objectif de cette étude est d'améliorer la compréhension de la formation d'hydrate et de comprendre comment l'additif dispersant évite l'agglomération. Pour ce faire, un modèle comportemental de la cristallisation pour les systèmes sans et avec additif a été développé. Il a également été proposé une technique pour déterminer la phase continue du système et un mécanisme d'action pour l'anti-agglomérant a été suggéréCrystallization of hydrates during oil production is a major source of hazards, mainly related to flow lines plugging after hydrate agglomeration. During the petroleum extraction, oil and water circulate in the flow line, forming an unstable emulsion. The water phase in combination with light hydrocarbon components can form hydrates. The crystallization of hydrates has been extensively studied, mainly at low water content systems. However, as the oil field matures, the water fraction increases and can become the dominant phase, a system less known in what concerns hydrate formation. Actually, several techniques can be combined to avoid or remediate hydrate formation. Recently, a new class of additives called Low Dosage Hydrate Inhibitor (LDHI) started to be studied, they are classified as Kinetic Hydrate Inhibitors (KHI-LDHI) and Anti-Agglomerants (AA-LDHI).This work is a parametric study about hydrate formation from emulsion systems ranging from low to high water content, where different flow rates and the anti-agglomerant presence were investigated. The experiments were performed at the Archimède flow loop, which is able to reproduce deep sea conditions. The goal of this study is enhancing the knowledge in hydrate formation and comprehending how the dispersant additive acts to avoid agglomeration. For this matter, it was developed a crystallization topological model for the systems without and with additive. A technique to determine the system continuous phase and a mechanism of the anti-agglomerant action from the chord length measurements were also proposed
9
Baur, Loïc. "Contributions expérimentales sur les écoulements à bulles en rotation". Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL131N.
Abstract (sommario):
Bien que les écoulements diphasiques tourbillonnaires soient largement rencontrés dans les procédés et dispositifs industriels, ils n'ont fait l'objet que d'études limitées. Ce mémoire traite des contributions que nous avons apportées à la connaissance de tels écoulements sur le plan expérimental. La configuration d'étude concerne un écoulement à bulles ascendant en conduite cylindrique verticale, qui traverse une structure alvéolaire tournante. Dans un premier temps, la boucle d'essais spécifique à cette étude ainsi que les différentes techniques de mesures utilisées sont décrites. Les résultats obtenus en monophasique sont alors donnés afin de qualifier le dispositif. Le comportement de la phase gazeuse est ensuite analysé par visualisations à l'aide de cameras et par des mesures de taux de vide local par sonde optique. La migration des bulles vers le centre de la conduite conduit à la formation d'un cœur dont le taux de vide peut atteindre 70% sans pour autant provoquer un régime annulaire. Ce cœur est de stabilité variable suivant les vitesses débitantes des deux phases et la vitesse de rotation. Enfin, des résultats de mesure de la pression pariétale et des vitesses sont donnés. Une bi-sonde optique est utilisée pour la phase gaz tandis que la vitesse de la phase liquide est mesurée par film chaud. Cette étude a donc permis de décrire la structure de l'écoulement et a apporté les premières données locales en vue d'une modélisation future
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Peytraud, Jean-François. "Étude de la tomographie électrique pour la mesure du taux de vide local en écoulements diphasiques". Grenoble INPG, 1995. http://www.theses.fr/1995INPG0035.
Abstract (sommario):
La modelisation des ecoulements diphasiques multidimensionnels se heurte a l'heure actuelle au probleme de la determination des phases en presence. On se propose ici d'etudier l'application d'une technique d'imagerie medicale, la tomographie electrique, a la determination de la distribution des phases en ecoulement diphasique. On montre, dans un premier temps, que la conception rationnelle du capteur tomographique ne peut etre envisage sans une etude approfondie du conditionnement numerique de l'algorithme de reconstruction. Ce dernier, developpe en geometrie bidimensionnelle, a pour objet de resoudre le probleme inverse de la determination des frontieres des phases en presence. Cet algorithme est base sur la methode iterative de newton-raphson. A chaque iteration le probleme direct est resolu par la methode des integrales de frontiere. L'etude du conditionnement de la reconstruction montre que pour des conditions compatible avec un ecoulement diphasique, il est deraisonnable de vouloir reconstruire plus de 2 frontieres d'inclusions. De plus, meme dans ce cas, les niveaux de precision des mesures ne peuvent etre atteint que si l'on maitrise les variations de temperature du milieu ainsi que des phenomenes d'impedance d'interface. L'apparition d'image fantome lors de la reconstruction de milieu 3d amene a penser que la solution pourrait etre l'utilisation d'un capteur 3d. Ceci augmente la complexite du systeme sans aucun gain au niveau du conditionnement rendant ainsi cette approche irrealiste. Cependant dans des cas simples (une frontiere), toutes les techniques mise en uvre ici permettent l'obtention d'une image precise de cette frontiere
Libri sul tema "Fraction de gaz":
1
Jing, Chen. BOREAS RSS-7 LAI, gap fraction, and FPAR data. Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 2000.
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Jing, Chen. BOREAS RSS-7 LAI, gap fraction, and FPAR data. Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 2000.
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Jing, Chen. BOREAS RSS-7 LAI, gap fraction, and FPAR data. Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 2000.
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Jing, Chen. BOREAS RSS-7 LAI, gap fraction, and FPAR data. Greenbelt, Md: National Aeronautics and Space Administration, Goddard Space Flight Center, 2000.
5
Yang, Yingjie. Fen shu: Ti gao xiao xue sheng shu xue cheng ji bi bei. 8a ed. [Xianggang]: Hai bin tu shu gong si, 1997.
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Zheng, Zhenchu. Fen shu jiao xue fen xi: Gai nian he yun suan. 8a ed. Taibei Shi: Jiu zhang chu ban she, 2006.
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C, Ku Jerry, e United States. National Aeronautics and Space Administration., a cura di. Brief communication: Soot volume fraction maps for normal and reduced gravity laminar acetylene jet diffusion flames. [Washington, DC: National Aeronautics and Space Administration, 1997.
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C, Ku Jerry, e United States. National Aeronautics and Space Administration., a cura di. Brief communication: Soot volume fraction maps for normal and reduced gravity laminar acetylene jet diffusion flames. [Washington, DC: National Aeronautics and Space Administration, 1997.
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R, Herring J., e Geological Survey (U.S.), a cura di. Size analysis, visual estimation of phosphate and other minerals, and preliminary estimation of recoverable phosphate in size fractions of sediment samples from drillholes GAT-90, Tybee Island, and GAS-90-2, Skidaway Island, Georgia. [Denver, CO]: U.S. Dept. of the Interior, U.S. Geological Survey, 1991.
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Griepink, B. The certification of the contents (mass fraction) of carbon, hydrogen, nitrogen, chlorine, arsenic, cadmium, manganese, mercury, lead, selenium, vanadium and zinc in three coals: Gas coal CRM No.180, coking coal CRM No.181, steam coal CRM No.182. Luxembourg: Commission of the European Communities, 1986.
Capitoli di libri sul tema "Fraction de gaz":
1
Ghajar, Afshin J. "Void Fraction". In Two-Phase Gas-Liquid Flow in Pipes with Different Orientations, 37–64. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-41626-3_4.
2
Wijffels, René H. "Gradients in Liquid, Gas or Solid Fractions". In Immobilized Cells, 182–90. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56891-6_17.
3
Oliveira, Maria João, e Rui Vilela Mendes. "Fractional Boson Gas and Fractional Poisson Measure in Infinite Dimensions". In From Particle Systems to Partial Differential Equations II, 293–312. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16637-7_11.
4
Boebinger, Gregory S. "Experimental Aspects of the Fractional Quantum Hall Effect". In The Physics of the Two-Dimensional Electron Gas, 51–96. Boston, MA: Springer US, 1987. http://dx.doi.org/10.1007/978-1-4613-1907-8_3.
5
Huygen, P. E. M., A. Hartog, C. Kolle, E. Oosterbosch e B. Lachmann. "An In-Line Oxygen Gas-Fraction Sensor for Anesthesia and Intensive Care". In Advances in Experimental Medicine and Biology, 579–83. Boston, MA: Springer US, 1997. http://dx.doi.org/10.1007/978-1-4615-5399-1_82.
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Liberto, E., C. Bicchi, C. Cagliero, C. Cordero, P. Rubiolo e B. Sgorbini. "Chapter 1. Headspace Sampling: An “Evergreen” Method in Constant Evolution to Characterize Food Flavors through their Volatile Fraction". In Advanced Gas Chromatography in Food Analysis, 1–37. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781788015752-00001.
7
Bertulessi, Luca. "Frequency Synthesizers Based on Fast-Locking Bang-Bang PLL for Cellular Applications". In Special Topics in Information Technology, 27–36. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-62476-7_3.
Abstract (sommario):
AbstractThe fractional-N frequency synthesis based on Digital Phase Locked Loop (DPLLs) has become a conventional design approach for the new radio wireless applications. The advantage of the digitally-intensive design style is the possibility to implement low-power and very accurate digital calibration techniques. Most of these algorithms run in the background tracking PVT variations and either relax or, in some cases, completely remove the performance limitations due to analog impairments. Moreover, the digital loop filter area is practically negligible with respect to the one in analog PLLs. These benefits become even more relevant in the scaled CMOS technology nodes. This chapter identifies the design parameters of a standard DPLL architecture and proposes a novel locking scheme to overcome the intrinsic limitations of the digital frequency synthesizers approach. To prove this new scheme a sub-6 GHz fractional-N synthesizer has been implemented in 65 nm CMOS. The synthesizer has an output frequency from 3.59 GHz to 4.05 GHz. The integrated output jitter is 182fs and the power consumption of 5.28 mW from 1.2 V power supply leads to a FoM of −247.5 dB. This topology exploits a novel locking technique that guarantee a locking time of 5.6 s, for a frequency step of 364 MHz, despite the use of a single bit phase detector.
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Avsievich, Alexandr, Vladimir Avsievich e Anton Ivaschenko. "Intelligent Fractional Control System of a Gas-Diesel Engine". In Lecture Notes on Data Engineering and Communications Technologies, 379–89. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9113-3_28.
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Asher, William, James Edson, Wade Mcgillis, Rik Wanninkhof, David T. Ho e Trina Litchendor. "Fractional Area Whitecap Coverage and Air-Sea Gas Transfer Velocities Measured During GasEx-98". In Gas Transfer at Water Surfaces, 199–203. Washington, D. C.: American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm127p0199.
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Addali, A., e D. Mba. "Acoustic Emission Technology for Assessing Gas Void Fraction Levels in Two-Phase Flow". In Engineering Asset Management and Infrastructure Sustainability, 31–38. London: Springer London, 2012. http://dx.doi.org/10.1007/978-0-85729-493-7_3.
Atti di convegni sul tema "Fraction de gaz":
1
Saab, Joseph, Ramy Abou Naccoul, Juliette Stephan, Rosette Ouaini, Jacques Jose e Naim Ouaini. "Dynamic Fluid Saturation Method for Hydrocarbons Thermodynamics’ Properties Determination". In ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37114.
Abstract (sommario):
Low solubility compounds suffer from lack of data, leading to an impoverishment in thermodynamic parameters such as Gibbs free energy (ΔG), enthalpy of dissolution (ΔH), entropy (ΔS), infinite dilution coefficient (γ∞) and isobaric heat capacity (Cp) of utmost practical importance for industrial optimization processes. Dynamic fluid method is a novel technique for low solubility (expressed as molar fraction χ) determination based on the saturation of a specific heated fluid passing through a saturation cell. The heated components are kept inside a chromatographic oven maintained at a constant temperature to within ± 0.05°C by means of a PID temperature controller. A regular stream of fluid, using a constant flow pump, passes through the saturation cell packed with an inert stationary phase (Gaz chrom R 60/80) pre-coated with the organic compound. The solute transported by the fluid is subsequently trapped in a specific extraction column (inverse phase). The organic compound is removed by back flushing using the appropriate solvent in order to dissolve and carry out the totality. A low flow of fluid through the generator column is to be set to avoid safely the formation of colloidal dispersion, to increase the contact time and to keep small pressure drops across the generator/extractor column. The gas chromatography coupled to mass spectrometer detector is used in order to quantify the solute. The validation of this apparatus was achieved by comparison of our values with the ones extracted from previous papers using the static method to determine aqueous solubility of the ethylbenzene, and a precision of our solubility measurements was established to be better than 0.2%. In continuous, aqueous solubility and thermodynamics properties of perfluorocarbons compounds were determined in the range of temperature from 273 K to 333 K. Considering the contribution of chromatographic, calibration and other operational errors, the combined measurement uncertainty (standard deviation) was established to be less than 3%.
2
Bilyaz, Serhat, e Ilker Tari. "Hydrodynamic and Thermal Modeling of Circulating Fluidized Bed Solar Receivers". In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-67230.
Abstract (sommario):
The riser tube solar receiver of a circulating fluidized bed solid particle absorption solar thermal energy system was numerically modeled for analyzing hydrodynamic and heat transfer behaviors of the solid particles in the riser. Hydrodynamics of the model is validated by comparing radial distribution of void fractions with an experimental study. For the heat transfer from the opaque walls of the receiver that is heated to high temperatures by the solar rays concentrated by the heliostat field, a simple fractional model is used in which radiative transfer is neglected and total heat flux is distributed to phases according to the instantaneous volume fractions at the boundary cells. MFIX: Multiphase Flow with Interphase eXchanges code of NETL is used with a 2.5D Eulerian-Eulerian computational model for transient simulations. The 2.5D grid is a combination of planar cells and cylindrical cells with the determined optimum fraction of planar cells of 0.15. For the solar receiver riser, transient and time averaged results of void fraction and gas and solid phase temperature distributions were numerically obtained and analyzed.
3
Talcott, Sarah M., e Theodore J. Heindel. "Gas Holdup in Opaque Cellulose Fiber Slurries". In ASME 2005 Fluids Engineering Division Summer Meeting. ASMEDC, 2005. http://dx.doi.org/10.1115/fedsm2005-77043.
Abstract (sommario):
Three different cellulose fiber types are used to study their effect on gas holdup and flow regime transition in a 10.2 cm semi-batch bubble column. The three natural fiber types include bleached softwood chemical pulp (softwood), bleached hardwood chemical pulp (hardwood), and bleached softwood chemithermomechanical pulp (BCTMP). Gas holdup is recorded over a range of fiber mass fractions (0 ≤ C ≤ 1.6%) and superficial gas velocities (Ug ≤ 23 cm/s). Experimental results show that gas holdup decreases with increasing fiber mass fraction. Homogeneous, transitional, and heterogeneous flow is observed for all three fiber types at low fiber mass fractions. All three fiber types produce similar results in the homogeneous flow regime while significant differences are recorded in the heterogeneous flow regime; those being low mass fraction hardwood (softwood) fiber slurries produce the highest (lowest) gas holdup. At higher fiber mass fractions, only pure heterogeneous flow is observed and softwood fiber slurries still produce the lowest gas holdup, although the differences in gas holdup between fiber types are small. The Zuber-Findlay drift flux model is used to describe the gas holdup results in cellulose fiber slurries when the flow conditions are heterogeneous. The Zuber-Findlay drift flux model is also used to identify the superficial gas velocity at which homogeneous flow is no longer observed with some success. Generally, the superficial gas velocity at which the flow deviates from homogeneous flow decreases with increasing fiber mass fraction.
4
Su, Xuefeng, e Theodore J. Heindel. "Effect of Gas Distributor on Gas Holdup in Fiber Suspensions". In ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/ht-fed2004-56222.
Abstract (sommario):
Two different aeration plates are used to study their effect on gas holdup and flow regime transition in fiber suspensions. Two gas distributors with different open areas (A = 0.57% and 2.14%) and the same orifice diameter (do = 1 mm) are used, and experiments are performed using three different Rayon fiber lengths (L = 3, 6, and 12 mm) over a range of superficial gas velocities (Ug ≤ 18 cm/s) and a range of fiber mass fractions (0 ≤ C ≤ 1.8%) in a 15.24 cm diameter semi-batch bubble column. Experimental results show that the distributor with A = 2.14% tends to produce lower gas holdup than the one with A = 0.57% for both air-water systems and fiber slurries. However, the effect of distributor open area on gas holdup diminishes at high fiber mass fractions (C ≤ 1.2%). Both distributors generate homogeneous, transitional, and heterogeneous flow regimes over the range of superficial gas velocities for air-water and low fiber mass fraction suspensions. However, the distributor with A = 2.14% enhances the flow regime transition, i.e., the superficial gas velocity at which the transitional flow regime appears is lower. Additionally, the fiber mass fraction at which purely heterogeneous flow is observed is lower when A = 2.14%.
5
Koskenhely, Kari, Ari Ämmälä, Hanna Jokinen e Hannu Paulapuro. "Refining Characteristics of Softwood Fibre Fractions". In Advances in Paper Science and Technology, a cura di S. J. I’Anson. Fundamental Research Committee (FRC), Manchester, 2005. http://dx.doi.org/10.15376/frc.2005.1.427.
Abstract (sommario):
The role of refining intensity and specific energy in refining of softwood kraft fibre fractions was studied. Several paper properties can be improved by selective refining of fractions. The tensile strength-dewatering resistance relationship benefits from low-intensity refining of the long-fibre fraction. The specific energy input determines the increase in fibre swelling which contributes to a higher sheet density and improved tensile strength. The apparent density-roughness relationship benefits from mild refining of the short-fibre fraction. Refining intensity has a strong effect on the magnitude of the gap between bar surfaces, on fibre shortening, and on the coarseness of fibres with high cell wall thickness. For the short-fibre fraction, which appeared to flocculate less, the maximum intensity causing “pad collapse” and more severe fibre shortening was lower than for the long-fibre fraction and feed pulp. The fraction-specific intensity and gap behaviour are believed to relate to the compressibility of flocs under the stress applied by bar surfaces – a phenomenon discussed in recent studies concerning the forces acting on fibre flocs.
6
Baughn, J. W., e N. Bagheri. "The Effect of Thermal Matching on the Thermodynamic Performance of Gas Turbine and IC Engine Cogeneration Systems". In ASME 1985 Beijing International Gas Turbine Symposium and Exposition. American Society of Mechanical Engineers, 1985. http://dx.doi.org/10.1115/85-igt-106.
Abstract (sommario):
Computer models have been used to analyze the thermodynamic performance of a gas turbine (GT) cogeneration system and an internal combustion engine (IC) cogeneration system. The purpose of this study was to determine the effect of thermal matching of the load (i.e., required thermal energy) and the output steam fraction (fraction of the thermal output, steam and hot water, which is steam) on the thermodynamic performance of typical cogeneration systems at both full and partial output. The thermodynamic parameters considered were; the net heat rate (NHR), the power to heat ratio (PHR), and the fuel savings rate (FSR). With direct use (the steam fractions being different); the NHR of these two systems is similar at full output, the NHR of the IC systems is lower at partial output, and the PHR and the FSR of the GT systems is lower than the IC systems over the full range of operating conditions. With thermal matching (to produce a given steam fraction) the most favorable NHR, PHR, and FSR depends on the method of matching the load to the thermal output.
7
AbdulKareem, Lokman A., Barry J. Azzopardi, Sebastian Thiele, Andrew Hunt e Marco J. Da Silva. "Interrogation of Gas/Oil Flow in a Vertical Using Two Tomographic Techniques". In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79840.
Abstract (sommario):
Two tomographic techniques have been applied to the flow in a 67 mm internal diameter vertical pipe. One is Electrical Capacitance Tomography (ECT) mounted on the outside of the non-conducting pipe wall. Another technique, known as the Wire Mesh Sensor (WMS) was used. The measuring systems provide time and cross-sectionally resolved information about the spatial distribution of the phases. The information can be used to obtain space and time averaged void fractions, radial profiles of time averaged void fraction and cross-sectional averaged time series of void fraction. Simultaneous measurements were made with the two techniques for gas superficial velocities of 0.05–5.5 m/s and liquid superficial velocities of 0–0.7 m/s with air and silicone oil as the fluids. Bubble, slug and churn flows were identified from the characteristic signatures of the Probability Density Functions of the cross-sectionally averaged void fraction. In addition, the detailed shape of individual large bubbles has been extracted. The output of both instruments shows clearly that the shapes of the large bubbles in slug flow are distinctly different from the smooth bullet-shaped. In this larger diameter pipe, the interface is much more disturbed. In addition, flow can be classified according to the sizes of bubbles present. Distributions of bubble sizes are presented and the fractions of gas flowing in different bubble sizes classes quantified.
8
Avila, Cristian, Guoqing Wang, Xuren Zhu, Et-Touhami Es-Sebbar, Marwan Abdullah, Mourad Younes, Aqil Jamal, Thibault Guiberti e William L. Roberts. "Lean Stability Limits and Exhaust Emissions of Ammonia-Methane-Air Swirl Flames at Micro Gas Turbine Relevant Pressure". In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-78304.
Abstract (sommario):
Abstract This study reports on the lean stability limits and exhaust emissions of ammonia-methane-air swirl flames with varied ammonia fuel fractions. A reduced-scale burner was manufactured, inspired by Ansaldo’s micro gas turbine AE-T100 burner, and it was installed inside a high-pressure combustion duct to operate at 4.5 bar. This pressure corresponds to that found at full-load in the actual micro gas turbine’s combustion chamber. The lean stability limits were measured by igniting the flame at an equivalence ratio of ϕ = 0.85 and then progressively decreasing the equivalence ratio until lean blowout. Emissions of CO2, NO, and N2O were recorded for different equivalence ratios and ammonia fractions. Rich flames at an equivalence ratio of ϕ = 1.20 were also considered. Results show that the equivalence ratio at lean blowout increases when the ammonia fraction increases and that all the ammonia fractions tested lead to flames more prone to lean blowout than the pure methane reference flame. The CO2 emissions are monotonically reduced by increasing the ammonia fraction, both for lean and rich flames. The NO emissions exceed many regulations limit regardless of the ammonia fraction for all lean equivalence ratios. N2O emissions are almost negligible, except for very lean equivalence ratios where the N2O mole fraction in the exhaust reaches unacceptably high values. Only rich ammonia-methane-air flames show good NO and N2O performance. Therefore, FTIR analysis was carried out to quantify the amount of the unburnt NH3 in the exhaust for these flames. Results show that unburnt NH3 concentration is invariant, around 200 ppmv, between 0.70 ≤ XNH3 ≤ 0.95. Data reported in this study provide insights for future work on combustors and after-treatment systems towards zero-emissions micro gas turbines.
9
Lessard, Étienne M., Robert C. Bowden e Sun-Kyu Yang. "Uncertainty Quantification of Low Void Fraction Measurements Using Wire-Mesh Sensors in Horizontal Air-Water Flows". In ASME 2016 Fluids Engineering Division Summer Meeting collocated with the ASME 2016 Heat Transfer Summer Conference and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/fedsm2016-7843.
Abstract (sommario):
The need for a revised methodology and uncertainty quantification for wire-mesh sensor void fraction measurements in horizontal low void fraction flow conditions was identified. Two-phase flow measurements were performed at a low-pressure, adiabatic and horizontal flow loop using wire-mesh sensors over a range of water superficial velocities from 3.5 to 5.5 m/s, air superficial velocities from 0.05 to 0.9 m/s and volumetric void fractions from 1 to 16% Using this proposed analysis, a corrected trend with average percent differences of 36, 21 and 6% was obtained for the low, medium and high gas flow rate cases, respectively, when comparing the wire-mesh sensor void fractions to two-phase pipe flow models. By combining these measurements of the void fraction with those of the interfacial velocity, the gas superficial velocity was calculated based on the physical theory, and compared to the superficial velocity measured by the flowmeters for validation purposes. An estimation of the uncertainty of these parameters showed that most of the measured parameters agreed reasonably with physical theory within 20%.
10
Uesawa, Shin-ichiro, Akiko Kaneko e Yutaka Abe. "Measurement of Void Fraction in Dispersed Bubbly Flow With Constant Electric Current Method". In 2012 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icone20-power2012-54510.
Abstract (sommario):
Void fraction is one of important physical values for gas-liquid two-phase flow in nuclear power plants, and it is an essential parameter for designs and performance evaluations of devices, including a core of BWR and so on. Therefore void fraction measurement with real time, high temporal resolution and high spatial resolution has been needed. In several void fraction measurement methods, electric measurement methods of void fraction can realize real-time measurement. In previous studies, conductance methods capacitance methods, wire mesh methods and tomography techniques have been studied. In the present study, we research on a constant electric current method. This method can measure void fraction with higher temporal resolution and simpler systems. In previous study, the constant electrical current method has been applied in annular flow mainly. However, the method cannot be applied to three dimensional dispersed bubbly flow. This is because void fraction is estimated by cross-section ratio of gas and liquid phases in this method. In the present study, Maxwell’s theory and polarization method are applied to calculation method of void fraction from voltage measured by constant electrical current method, and we try to measure void fraction in dispersed bubbly flow. Maxwell’s theory is a calculation of a mixture with two materials of different conductivity. The polarization method proposed in this study assumes bubbles to be dielectric bodies and void fraction is estimated by the polarization electric field of the bubbles. In the experimental results, the void fractions in the three dimensional dispersed bubbly flow can be estimated with Maxwell’s theory and the polarization method. The void fractions estimated with these methods are more accurately than the previous method. Furthermore, it is experimentally clarified that the present proposed method can follow highly temporal void fluctuations of bubbly and froth flows. In addition, effects of intervals between electrodes and structures of electrodes are experimentally investigated.
Rapporti di organizzazioni sul tema "Fraction de gaz":
1
Snowdon, L. R. Saturate fraction gas chromatograms. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1996. http://dx.doi.org/10.4095/207700.
2
Snowdon, L. R. Saturate fraction gas chromatograms for Mackenzie Delta crude oils. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2000. http://dx.doi.org/10.4095/211485.
3
Stewart, C. W., G. Chen e J. M. Alzheimer. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument. Office of Scientific and Technical Information (OSTI), febbraio 1999. http://dx.doi.org/10.2172/3362.
4
Stewart, Charles W., James M. Alzheimer, Guang Chen e Perry A. Meyer. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument. Office of Scientific and Technical Information (OSTI), ottobre 1998. http://dx.doi.org/10.2172/965244.
5
CW Stewart, G Chen, JM Alzheimer e PA Meyer. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument. Office of Scientific and Technical Information (OSTI), novembre 1998. http://dx.doi.org/10.2172/1661.
6
Fowler, M. G., e M. Obermajer. Saturate fraction gas chromatograms of Jeanne d'Arc Basin source rock extracts. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2001. http://dx.doi.org/10.4095/212718.
7
Bajwa, Abdullah, e Timothy Jacobs. PR-457-17201-R01 Residual Gas Fraction Estimation Based on Measured In-Cylinder Pressure. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), settembre 2018. http://dx.doi.org/10.55274/r0011519.
Abstract (sommario):
Developing a reliable means of predicting and controlling engine operation at various operating conditions may be a reasonable pathway for meeting increasingly stringent engine emission regulations. In order to do so, estimates of the mixture composition at the end of the gas exchange process (i.e. at exhaust port closure, or EPC) are helpful for having accurate models of engine combustion. A substantial fraction of the trapped charge mixture is composed of residual gases from previous cycles. This fraction, the trapped residual fraction, changes combustion characteristics of the trapped mixture. Residual gases dilute the fresh charge, thus decreasing the flame speed and temperature. Moreover, because of their spatial inhomogeneity, especially around the spark plug, these gases seem to have implications for engine stability. All these factors likely affect engine performance and emissions. Unfortunately, it is not practical to directly measure the trapped residual fraction for engines operating in the field. To overcome this, computational models can be developed for control applications which estimate this fraction based on some measurable engine parameters e.g. manifold pressures, temperatures, etc. Currently, such models aren't readily available for stationary two-stroke natural-gas engines. This report summarizes the results of phase I of a multi-phase project. In this phase a GT-Power based model was developed for an Ajax E-565 single-cylinder engine to study various factors that influence the removal, or lack thereof, of residual gases from the engine cylinder. The model was used to successfully simulate various engine operating conditions and study the scavenging characteristics of the engine. Various steps followed in the development of the model have been discussed in the report, and at the end some preliminary results and recommendations for the next phase of the project have been presented.
8
Fowler, M. G., e M. Obermajer. Gasoline range and saturate fraction gas chromatograms of Jeanne d'Arc Basin crude oils. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2001. http://dx.doi.org/10.4095/212288.
9
Bajwa, Abdullah, e Timothy Jacobs. PR-457-17201-R02 Residual Gas Fraction Estimation Based on Measured Engine Parameters. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), febbraio 2019. http://dx.doi.org/10.55274/r0011558.
Abstract (sommario):
Gas exchange processes in two-stroke internal combustion engines, commonly referred to as scavenging, are responsible for removing the exhaust gases in the combustion chamber and preparing the combustible fuel-oxidizer mixture that undergoes combustion and converts the chemical energy of the fuel into mechanical work. Scavenging is a complicated phenomenon because of the simultaneous introduction of fresh gases into the engine cylinder through the intake ports, and the expulsion of combustion products from the previous cycles through the exhaust ports. A non-negligible fraction of the gaseous mixture that is trapped in the cylinder at the conclusion of scavenging is composed of residual gases from the previous cycle. This can cause significant changes to the combustion characteristics of the mixture by changing its composition and temperature, i.e. its thermodynamic state. Thus, it is vital to have accurate knowledge of the thermodynamic state of the post-scavenging mixture to be able to reliably predict and control engine performance, efficiency and emissions. Two tools for estimating the trapped mixture state - a simple scavenging model and empirical correlations - were developed in this study. Unfortunately, it is not practical to directly measure the trapped residual fraction for engines operating in the field. To overcome this handicap, simple scavenging models or correlations, which estimate this fraction based on some economically measurable engine parameters, can be developed. This report summarizes the results of event-II of a multi-event project that aims to develop such mathematical formulations for stationary two-stroke natural gas engines using data from more advanced models and experimentation. In this event, results from a GT-Power based model for an Ajax E-565 single-cylinder engine are used to develop a three-event single zone scavenging model and empirical correlations. Both of these mathematical devices produce accurate estimates of the trapped mixture state. The estimates are compared to GT-Power results. In the next event of the project, these results will be validated using experimental data. Various steps followed in the development of the model have been discussed in this report, and at the end some results and recommendations for the next event of the project have been presented.
10
D'Amore, F., e A. H. Truesdell. Calculation of geothermal reservoir temperatures and steam fractions from gas compositions. Office of Scientific and Technical Information (OSTI), gennaio 1985. http://dx.doi.org/10.2172/6060131.