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Artykuły w czasopismach na temat "Mixing Intensification"
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Gaynullina, L. R., i V. P. Tutubalina. "Mixing intensification". IOP Conference Series: Earth and Environmental Science 288 (25.07.2019): 012086. http://dx.doi.org/10.1088/1755-1315/288/1/012086.
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Wu, Jie, L. J. Graham i N. Noui-Mehidi. "Intensification of Mixing". JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 40, nr 11 (2007): 890–95. http://dx.doi.org/10.1252/jcej.06we254.
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Keil, Frerich J. "Process intensification". Reviews in Chemical Engineering 34, nr 2 (23.02.2018): 135–200. http://dx.doi.org/10.1515/revce-2017-0085.
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Abstract Process intensification (PI) is a rapidly growing field of research and industrial development that has already created many innovations in chemical process industry. PI is directed toward substantially smaller, cleaner, more energy-efficient technology. Furthermore, PI aims at safer and sustainable technological developments. Its tools are reduction of the number of devices (integration of several functionalities in one apparatus), improving heat and mass transfer by advanced mixing technologies and shorter diffusion pathways, miniaturization, novel energy techniques, new separation approaches, integrated optimization and control strategies. This review discusses many of the recent developments in PI. Starting from fundamental definitions, microfluidic technology, mixing, modern distillation techniques, membrane separation, continuous chromatography, and application of gravitational, electric, and magnetic fields will be described.
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Ohmura, Naoto, Hayato Masuda i Steven Wang. "Intensification of Mixing Processes with Complex Fluids". JOURNAL OF CHEMICAL ENGINEERING OF JAPAN 51, nr 2 (2018): 129–35. http://dx.doi.org/10.1252/jcej.17we149.
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Guo, Kai, Botan Liu, Qi Li i Chunjiang Liu. "Novel optimization approach to mixing process intensification". Transactions of Tianjin University 21, nr 1 (styczeń 2015): 1–10. http://dx.doi.org/10.1007/s12209-015-2434-8.
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Lebedev, Anatoly, Badma Salaev, Baatr Bolaev, Jury Arylov, Pavel Lebedev i Nikolai Rybalkin. "INTENSIFICATION OF THE PROCESS OF MIXING FEED MIXTURES". SCIENCE IN THE CENTRAL RUSSIA, nr 6 (26.12.2022): 50–59. http://dx.doi.org/10.35887/2305-2538-2022-6-50-59.
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The quality and reliability of the technological process of preparing feed mixtures has a significant role both on the properties of the manufactured product and on the productivity of animals. The use of standard mixer designs, as a rule, does not ensure the quality of mixtures, economy, efficiency and leads to an increase in energy costs for the implementation of the technological process. Despite the presence of a wide variety in mixer designs, the need for new mixer developments remains an urgent problem associated with the constant increase in requirements for the uniformity of feed mixtures. When preparing combined feeds of own production, the degree of uniformity should be 90...95%. The study of the mixing process was carried out for a two-shaft bladed mixer of continuous operation. During the research, three variants of the operation of the paddle mixer were considered, differing from each other in the number and size of the blades. The greatest intensity of mixing was in a mixer with smaller blades, but at the same time the segregation period was more than 50%. In all variants, 30...50% of the time is spent on convective mixing. High-quality mixing will be ensured by increasing the number of force impacts of the blades in the elementary mixing zones, which determine the total length of the continuous mixer. A new theoretical dependence of the mixing kinetics in a continuous-action paddle mixer is obtained. The formula shows that increasing the uniformity of the finished feed mixture can be achieved by controlling the mixing process and improving the working bodies of mixers. The efficiency of the mixing process is ensured first by creating a preliminary value of the homogeneity of the mixture Θ0, outside the mixing chamber, and then by varying the mixer parameters to ensure the required quality of the feed mixture. The obtained dependence is the basis for a new method of gravitational mixing and a device for its implementation.
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Ivanov, M. V., i B. S. Ksenofontov. "Intensification of Chemical Agents Mixing by Vibroacoustical Agitation". Ecology and Industry of Russia 21, nr 9 (1.01.2017): 4–9. http://dx.doi.org/10.18412/1816-0395-2017-9-4-9.
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Tamminen, Jussi, Tuomo Sainio i Erkki Paatero. "Intensification of metal extraction with high-shear mixing". Chemical Engineering and Processing: Process Intensification 73 (listopad 2013): 119–28. http://dx.doi.org/10.1016/j.cep.2013.08.005.
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Ahoure, Louis, Odin Bulliard-Sauret, Christophe Andre, Julie Bergraser, Marion Gaudeau i S. Amir Bahrani. "Intensification of mixing in an ultrasonic flow reactor". Chemical Engineering and Processing - Process Intensification 183 (styczeń 2023): 109212. http://dx.doi.org/10.1016/j.cep.2022.109212.
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Li, Zhen, Chengqian Zhao, Huaiqing Zhang, Jiongtian Liu, Chao Yang i Shanxin Xiong. "Process intensification of stirred pulp-mixing in flotation". Chemical Engineering and Processing - Process Intensification 138 (kwiecień 2019): 55–64. http://dx.doi.org/10.1016/j.cep.2019.03.008.
Pełny tekst źródłaRozprawy doktorskie na temat "Mixing Intensification"
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Zhang, Fan. "Intensification du procédé antisolvant supercritique (SAS) par l'usage de microréacteur sous pression". Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0269.
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Dans le cadre de cette thèse, nous nous proposons d’étudier le comportement thermo-hydrodynamique d’un mélange solvant/antisolvant supercritique dans une puce microfluidique, pour des conditions utilisées dans le procédé SAS (Supercritical Antisolvent System). Ce travail se base sur une approche complémentaire expérience/simulation via l’utilisation de techniques de recherches avancées telles que la caractérisation in situ sur puce microfluidique (micro-PIV – micro Particle Image Velocimetry) et la simulation numérique intensive. L’objectif de la thèse est de définir les conditions favorables à un « très bon » mélange (total et rapide) des espèces en termes de vitesse, température, pression et « design » d’injecteur. Les simulations sont effectuées avec le code de calcul Notus, massivement parallèle. Après un premier chapitre détaillant l’état de l’art sur les procédés antisolvant supercritiques, puis un second concernant les méthodologies utilisées (modèle numérique, outils microfluidiques), nous comparons dans un premier temps les résultats des simulations numériques à ceux obtenus avec les expériences de micro-PIV en écoulement laminaire. La comparaison est très bonne pour l’ensemble des expériences réalisées. Le code de calcul ainsi validé, nous proposons d’utiliser l’outil numérique comme véritable outil de recherche des meilleures conditions opératoires pour favoriser le mélange. Pour cela, des simulations du mélange de deux fluides (typiquement CO2 et éthanol) sont effectuées pour différentes conditions opératoires (vitesse, température, pression) pour des conditions laminaires mais également en conditions turbulentes, régime rarement atteint à ces échelles de réacteur. En effet, nous avons montré expérimentalement que le régime turbulent pouvait être atteint dans le microcanal grâce à la technologie « microfluidique haute pression » développé au laboratoire. L’étude de la qualité du mélange se base sur deux critères communément utilisées dans la littérature. Le premier est l’index de ségrégation basé sur la variance du champ de concentration ou fraction massique dans notre cas. Celui-ci peut être estimé pour tous les cas de simulation, du laminaire au turbulent. Le deuxième critère est le temps de micromélange basé sur l’estimation du taux de dissipation de l’énergie cinétique turbulente. Celui-ci est calculé uniquement dans les cas turbulents car basé sur les fluctuations des vitesses par rapport à la valeur moyenne. Un des intérêts majeurs de l’utilisation des puces microfluidiques réside notamment dans ses faibles échelles de temps et d’espace. D’un point de vue numérique, de telles échelles permettent, dans des temps de calcul raisonnables, de proposer des simulations numériques directes (DNS), i.e., dont les plus petites mailles sont inférieures ou très proches de l’échelle de Kolmogorov. Ceci est de tout premier intérêt car nous sommes capables de capter les plus petites échelles du mélange et notamment le micromélange. Ainsi, les résultats de simulation nous ont permis de proposer une analyse fiable du mélange d’un point de vue qualitatif et quantitatif, faisant la preuve que les conditions de mélange dans ce type de dispositif sont particulièrement favorables pour l’élaboration de matériaux par antisolvant supercritique. Les conditions optimales de mélange ainsi déterminées, nous proposons dans une dernière partie de simuler la synthèse de nanoparticules organiques dans de tels dispositifs. L’approche numérique est basée sur un couplage des équations de la mécanique des fluides et d’une équation de bilan de population permettant de prendre en compte la nucléation et croissance des particules. Les résultats de simulation ont été comparés avec succès avec ceux expérimentaux obtenues au laboratoireIn the context of this thesis, we propose to study the thermo-hydrodynamic behavior of a mixture, a solvent and a supercritical antisolvent (CO2) in a microfluidic chip, for conditions used in the Supercritical Antisolvent (SAS) process. This work is based on a complementary approach of both experiments and simulations through the use of advanced research techniques, such as the in situ characterization inside the microfluidic reactor (Micro-Particle Image Velocimetry) and the High Performance Computing. The objective of the thesis is to determine the favorable conditions for a "very good" mixture (total and fast) of species in terms of velocity, temperature, pressure and injector "design". The simulations are performed with the massively parallel code Notus. After the first chapter detailing the state of the art on the supercritical antisolvent processes, then the second concerning the applied methodologies (numerical model, microfluidic tools), we first compare the results of the numerical simulations to the experimental data obtained by micro-PIV in laminar flow conditions. The simulation results are in good agreement with the experiments. After the validation of the numerical code, we propose to use the numerical tool to determine the optimal operating conditions of mixing. For this, simulations of the mixture of two fluids (typically CO2 and ethanol) are performed for different operating conditions (velocity, temperature, pressure) for laminar conditions but also for turbulent conditions, a regime rarely reached in microreactors. Indeed, we have shown experimentally that the turbulent mixing could be reached in the microchannel thanks to the "high pressure microfluidic" technology developed in the laboratory. The study of the mixing quality is based on two criteria commonly used in the literature. The first is the segregation intensity based on the variance of the ethanol concentration. This can be estimated for all simulation cases, from laminar to turbulent mixing. The second criterion is the micromixing time related to the turbulent kinetic energy dissipation rate directly estimated from the local velocity fluctuations in turbulent flow conditions. One of the major interests of the use of microfluidic reactors lies especially in its small scales of time and space. From a numerical point of view, such scales allow, within reasonable CPU time, to perform direct numerical simulations (DNS), i.e., in which the grid size is smaller or very close to the Kolmogorov scale. This is of primary interest because we are able to capture the smallest scales of the mixture including the micromixing. Thus, the simulation results allow us to propose a reliable analysis of the mixture from both qualitative and quantitative point of view, proving that the mixing conditions in this type of device are particularly favorable for the material synthesis by supercritical antisolvent. After determining the optimal mixing conditions, we propose in a final part to simulate the synthesis of organic nanoparticles in such devices. The numerical approach is based on the coupling between the CFD code and a population balance equation to take into account the nucleation and growth of particles. The simulation results are also in a good agreement with the experimental measurements performed in the laboratory
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Zambaux, Julie-Anne. "Influence des déformations successives alternées de la paroi sur l'accroissement des performances d'échange d'un tube : application aux échangeurs multifonctionnels". Thesis, Valenciennes, 2014. http://www.theses.fr/2014VALE0036/document.
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Les travaux de thèse sont consacrés à l’étude numérique de l’application de macro-déformations successives alternées a la paroi d’un tube. La modification de l’écoulement du fait des déformations permet de modifier ses propriétés en termes de transfert thermique et de mélange. L’objectif de l’étude d’un tel dispositif est entre autre de l’appliquer pour des configurations d’échangeurs multifonctionnels, qui sont à la fois échangeurs de chaleur et réacteurs chimiques. L’étude s’intéresse principalement aux écoulements laminaires. Les calculs sont réalisés avec le code ANSYS Fluent. L’étude est tout d’abord consacrée à la caractérisation de l’écoulement secondaire créé par les déformations ainsi qu’à l’influence des différents paramètres de déformation. Afin d’améliorer le mélange dans l’écoulement, l’étude d’une configuration coaxiale déformée a été envisagée (cette géométrie correspond de plus à une configuration d’écoulement utilisée dans l’industrie). Deux configurations annulaires ont été considérées. Dans un premier temps, les déformations pariétales ont été appliquées aux tubes interne et externe : différents déphasages longitudinaux et angulaires entre ces deux déformations ont été étudiés pour optimiser les performances thermo-hydrauliques. La seconde configuration combine des déformations sur la paroi externe et un swirl sur la paroi interne de la géométrie. Cette configuration particulière permet en régime laminaire d’augmenter significativement le mélange du fait de l’apparition d’advection chaotique dans l’écoulement. Cette dernière géométrie est appliquée dans le cas d’un échangeur solaire à concentration et permet d’améliorer les performances par rapport à un tube lisse dans des conditions similaires. La dernière partie de l’étude est consacrée à une validation expérimentale des résultats numériques lorsque les déformations sont appliquées à une plaque. Des mesures par PIV et LDA ont été réalisées pour mesurer la vitesse locale de l’écoulementThe work presented here is focused on the numerical study of specific successive wall deformations in alternate directions, applied to a tubular geometry. Those deformations help modifying the flow structure and thus its heat transfer and mixing properties. One of the main aims of the study is to apply those deformations to multifunctional exchangers which are heat exchangers and chemical reactors at the same time. The study is mainly focused on laminar flows and all the numerical calculations were performed using the CFD code ANSYS Fluent. The first step of the study is to assess the secondary flow created by the wall deformations. The influence of several deformation geometrical parameters has also been studied. In order to enhance the mixing in the deformed tube, the wall deformations have been applied to coaxial configurations (often used in the industry). Two kinds of annular configurations have been evaluated. At first, the wall deformations are applied to the external and internal walls of the coaxial tube. The effect on the heat transfer enhancement of the longitudinal and angular phase-shifting between the two deformations has been specifically assessed. The second configuration considered combines the alternate deformations on its external walls and a swirled internal wall. This particular annular configuration creates chaotic advection in laminar flows, therefore helping increasing the mixing. This geometry is used as a solar captor and helps increasing the global performances when compared with a smooth tube usually used. The last part of the presented work is focused on the experimental validation of the numerical results. Techniques such as PIV and LDA are used to measure local velocity fields in a plane duct with alternate deformations applied to its lower wall
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Souzy, Mathieu. "Mélange dans les suspensions de particules cisaillées à bas nombre de Reynolds". Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4719/document.
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J'ai étudié expérimentalement, à l'échelle de la taille des particules, les mécanismes à l'origine de l'intensification des transferts ayant lieu dans les suspensions cisaillées de particules non-inertielles et non-Browniennes. Dans un premier temps, l'expérience de Taylor est revisitée en étudiant l'évolution d'une goutte de colorant soumise à un cisaillement périodique. Au-delà d'une amplitude critique de déformation, la présence des particules brise la réversibilité du système et induit une forte dispersion de la goutte de colorant. Ensuite, en m'intéressant au transfert en proche paroi, j'ai montré que la rotation des particules sur la paroi induit un transport à flux constant d'un scalaire jusque dans le bulk de la suspension, brisant la couche limite diffusive. Une solution analytique du profil de concentration dans cette zone est proposée, en bon accord avec les expériences. Finalement, des mesures PIV haute résolution du fluide interstitiel dans le bulk de la suspension ont été réalisées. A partir de ces champs de vitesses, on a reconstruit l'historique d'étirement de lignes matérielles du fluide et ainsi déterminé les lois d'étirement, information fondamentale pour la compréhension du processus de mélange. La présence des particules change les lois d'étirement qui passent de linéaires dans un fluide pur, à exponentielles en présence de particules. Un modèle d'étirements multiplicatifs est proposé, qui prédit quantitativement l'évolution de la moyenne, de la variance, et la forme log-normale des distributions d'étirements mesurées expérimentalement. L'inhomogénéité des étirements dans les suspensions cisaillées implique une large distribution du temps de mélangeMainly based on experiments, I investigated at a particle scale the mechanisms at the origin of the transfer enhancement in sheared non-Brownian and non-inertial particulate suspensions. First, I revisited Taylor's experiment, investigating the evolution of a drop of dye in a periodic shear. Beyond a critical strain amplitude, the presence of the particles breaks the reversibility of the system and the drop of dye is rapidly dispersed in the surrounding medium. Then, investigating the transfer process in the wall vicinity, I showed that in this region, the rotation of the particles convectively transport a scalar at a constant rate directly from the wall towards the bulk of the suspension, breaking the diffusive boundary layer. An analytical solution for the concentration profile in this region is proposed, in good agreement with experimental measurements. Lastly, high-resolution PIV measurements of the fluid phase were performed in the bulk of the suspension. Using these velocity fields, we reconstructed the stretching histories of fluid material lines to determine the stretching laws, crucial for the understanding of the mixing process. The presence of the particles changes the very nature of the stretching laws from linear, in a pure fluid, to exponential in the presence of particles. A multiplicative stretching model is proposed, which quantitatively predicts the experimentally measured evolution of the mean and the variance of the elongations of the fluid material lines as well as their evolution towards a log-normal distribution. The strong stretching inhomogeneity in sheared suspensions results in a broad distribution of the mixing time
Książki na temat "Mixing Intensification"
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Kolmičkovs, Antons. Electric Field Effect on Combustion of Pelletized Biomass in Swirling Flow. RTU Press, 2022. http://dx.doi.org/10.7250/9789934227257.
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The Doctoral Thesis examines the control of the swirling flame flow dynamics with an external static electric field by firing the gaseous products of thermal decomposition of pelletized straw, woody biomass, and peat with the aim of more efficient heat production with a decrease of flue gas emissions. The intensification of the downward vortex in the electric field has been determined, ensuring improved mixing of the air vortex with the biomass thermal decomposition gas flow, intensifying the convective mass transfer towards the heating surfaces, and increasing the amount of heat energy produced in the biomass thermochemical conversion process.
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Symon, Gillian, Katrina Pritchard i Christine Hine, red. Research Methods for Digital Work and Organization. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780198860679.001.0001.
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Digital work is organizationally, interpretively, spatially, and temporally complex. An array of innovative methodologies have begun to emerge to capture these activities, whether through re-purposing existing tools, devising entirely novel methods, or mixing old and new. This book brings together some of these techniques in one volume as a sourcebook for management, business, organizational and work researchers pursuing projects in this field. The specific objectives of the book are to: present a range of innovative methods which capture and analyse digitally-related work practices through reflexive accounts of real world research projects; provide an accessible sourcebook of these methods for the business and management research community; elucidate the range of challenges such methods may raise for research practice, outlining debates and recommendations; and provide further reading and information to support research practice. The book is organized in four sections that reflect researchers’ different areas of focus and methodological approaches: working with screens; digital working practices; distributed work and organizing; and digital traces of work. Each chapter provides a reflexive account of researchers’ own experiences in developing methods that capture digital aspects of work and organization. We conclude by reflecting on the future of research given the current intensification of digital work during a global pandemic that is impacting all aspects of our lives.
Części książek na temat "Mixing Intensification"
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Isaenkov, Y. I., S. B. Leonov i M. N. Shneider. "Mixing Intensification by Electrical Discharge in High-Speed Flow". W New Trends in Fluid Mechanics Research, 182–85. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-75995-9_55.
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"Intensified mixing". W Process Intensification, 215–21. Elsevier, 2008. http://dx.doi.org/10.1016/b978-0-7506-8941-0.00008-0.
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Reay, David, Colin Ramshaw i Adam Harvey. "Intensified Mixing". W Process Intensification, 251–58. Elsevier, 2013. http://dx.doi.org/10.1016/b978-0-08-098304-2.00007-9.
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Sanchez-Claros, Maria, Joaquin Ortega-Casanova i Francisco Jose Galindo-Rosales. "2D Numerical Study of a Micromixer Based on Blowing and Vortex Shedding Mechanisms". W Process Analysis, Design, and Intensification in Microfluidics and Chemical Engineering, 79–113. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7138-4.ch003.
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In this chapter, a numerical study and assessment of the mixing efficiency of a novel microfluidic device for mixing two fluids are presented. The device under study consists of a two-dimensional straight microchannel with a square pillar centered across the channel. The main fluid flows through the microchannel from the main inlet to the outlet, while the second fluid is injected through the pillar as two small jets at its upstream corners. For different values of the Reynolds number, intensity ratio between the jets and the main channel stream and jets injection angle, the authors have conducted several numerical simulations to characterize both the mixing efficiency and the required input power to make the fluids flow. The optimum configuration has been revealed for high values of the Reynolds number, low intensity ratios, and high injection angles. Thanks to vortex shedding and the corresponding downstream oscillations, a mixing efficiency of around 90% can be reached. The worst mixing efficiency is obtained for a configuration without vortex shedding, having a mixing efficiency of only around 2%.
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Leanage, Neluka, i Pierre Filion. "Pandemic-and Future-Proofing Cities: Pedestrian-oriented Development as an Alternative Model to Transit-based Intensification Centers". W Volume 3: Public Space and Mobility, 187–98. Policy Press, 2021. http://dx.doi.org/10.1332/policypress/9781529219005.003.0018.
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Many official smart growth inspired Canadian plans limit sprawl by mixing land uses, transportation modes, jobs and residents to create compact, transit-oriented, multi-functional, intensification centres enriched with amenities and highly designed public spaces. However, these intensification strategies, built on new or expanded public transit systems at metropolitan, regional and local planning scales, face challenges amid the 2020 pandemic. Recovery from the combined COVID-19-induced loss of commercial activity in intensification centres and confidence in public transit could take years, and combined with an increased reliance on private vehicles, could undo decades of planning efforts at shifting unsustainable land use-transportation dynamics. This chapter proposes as an alternative, or complementary, intensification approach, a pedestrian-oriented development (POD) model inspired by the ‘15-minute city’ being considered across the world.
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Masuda, Hayato. "Enhancement of Heat Transfer Using Taylor Vortices in Thermal Processing for Food Process Intensification". W Food Processing – New Insights [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99443.
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We are witnessing a transition from the traditional to novel processing technologies in the food industry to address the issues regarding energy, environment, food, and water resources. This chapter first introduces the concept of food process intensification based on vortex technologies to all food engineers/researchers. Thereafter, the novel processing methods for starch gelatinization/hydrolysis and heat sterilization based on Taylor–Couette flow are reviewed. In fluid mechanics communities, the Taylor–Couette flow is well-known as a flow between coaxial cylinders with the inner cylinder rotating. Recently, this unique flow has been applied in food processing. In starch processing, enhanced heat transfer through Taylor vortex flow significantly improves gelatinization. In addition, effective and moderate mixing leads to an increase in the reducing sugar yield. In sterilization processing, the enhanced heat transfer also intensifies the thermal destruction of Clostridium botulinum. However, a moderate heat transfer should be ensured because excessive heat transfer also induces thermal destruction of the nutritional components. The Taylor–Couette flow is only an example considered here. There are various flows that intensify the heat/mass transfer and mixing in food processing. It is expected that this chapter will stimulate the development of food processing based on fluid technologies, toward food process intensification.
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Szaszák, N., P. Bencs i Sz Szabó. "Intensification of turbulent mixing in gases by means of active turbulence grid". W Advances and Trends in Engineering Sciences and Technologies III, 597–602. CRC Press, 2019. http://dx.doi.org/10.1201/9780429021596-94.
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Doraiswamy, L. K. "Introduction and Structure of the Book". W Organic Synthesis Engineering. Oxford University Press, 2001. http://dx.doi.org/10.1093/oso/9780195096897.003.0005.
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A large part of the chemical industry is concerned with organic chemicals from simple to highly complex structures. In dealing with relatively simple structures, there does not appear to be any need usually for a deeper understanding of chemistry than that to which an engineer is normally exposed. Most reaction engineering texts are written with this basic assumption. Catalysis, which is invariably an integral part of the reaction engineer’s arsenal, has been limited to the production of large volume chemicals which are often relatively simple in structure. Increasing attempts by chemists today to extend the use of catalysis to the production of medium and small volume chemicals has triggered a change in perspective that augers well for a closer liaison between chemists and engineers. We examine this a little further below by defining an organic chemicals ladder, and the merging roles of the two in exploiting this ladder, particularly for chemicals stacked on its intermediate rungs. Another change that is taking place is the increasing role of process intensification, nowhere more evident than in the production of organic chemicals. Process intensification means improvement of a process, mainly the reaction, by any possible means, to increase the overall productivity. This usually takes the form of reaction rate enhancement by extending known or emerging laboratory techniques to industrial scale production. These techniques can be engineering intensive, chemistry intensive, or both. Examples are the use of ultrasound (sonochemistry), light (photochemistry), electrons (electrochemistry), enzymes (biotechnology), agents for facilitating a reaction between immiscible phases (phase-transfer catalysis), microparticles (microphase engineering), membranes (membrane reactor engineering), a second phase (biphasing), combinations of reactions with different techniques of separation (multifunctional or combo reactor engineering), and mixing. Their use in the production of medium and small volume chemicals like pesticides, drugs, Pharmaceuticals, perfumery chemicals, and other consumer products is being increasingly explored both by industry and academe. Some of these techniques have progressed little beyond the laboratory stage, although they have been a part of the synthetic organic chemist’s repertoire for a number of years. Thus, in addition to the use of catalysis in its various forms, this book will also explore different techniques of reaction rate and/or selectivity enhancement.
Streszczenia konferencji na temat "Mixing Intensification"
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Lemenand, Thierry, Pascal Dupont, Dominique Della Valle i Hassan Peerhossaini. "Turbulent Mixing of Two Immiscible Fluids". W ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45781.
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The global trend in chemical and manufacturing industries is towards improved energy efficiency, cleaner synthesis, reduced environmental impact and smaller, safer, multifunctional process plants. Such concerns are the driving force for the intensification of batch processes, which are being replaced with continuous high-intensity in-line mass- and heat-transfer equipment. In this context the process intensification (PI) approach, in which the fluid dynamics of the process is matched to the reaction in order to improve selectivity and minimize the byproducts, takes on particular importance.
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Timite, Brahim, Cathy Castelain i Hassan Peerhossaini. "Pulsating Flow for Mixing Intensification in a Twisted Curved Pipe". W ASME/JSME 2007 5th Joint Fluids Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/fedsm2007-37065.
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This work concerns the manipulation of a twisted curved pipe flow for mixing enhancement. Previous work [1,2,3] has shown that geometrical perturbations to a curved pipe flow can increase mixing and heat transfer by chaotic advection. In this work the flow entering the twisted pipe undergoes a pulsatile motion. The flow was studied experimentally and numerically. The numerical study is carried out by CFD code (Fluent 6) in which a pulsated velocity field is imposed as an inlet condition. The experimental setup involves principally a “Scotch-yoke” pulsatile generator and a twisted curved pipe. Laser Doppler velocimetry (LDV) measurements have shown that the Scotch-yoke generator produces pure sinusoidal instantaneous mean velocities with a mean deviation of 3%. Visualizations by laser-induced fluorescence (LIF) and velocity measurements, coupled with the numerical results, have permitted analysis of the evolution of the swirling secondary flow structures that develop along the bends during the pulsation phase. These measurements were made for a range of steady Reynolds number (300 ≤ Rest ≤ 1200), frequency parameter (1 ≤ α = r0.(ω/υ)1/2 < 20), and two velocity components ratios (β = Umax,osc/Ust). We observe satisfactory agreement between the numerical and experimental results. For high β, the secondary flow structure is modified by a Lyne instability and a siphon effect during the deceleration phase. The intensity of the secondary flow decreases as the parameter α increases during the acceleration phase. During the deceleration phase, under the effect of reverse flow, the secondary flow intensity increases with the appearance of Lyne flow. Experimental results also show that pulsating flow through a twisted curved pipe increases mixing over the steady twisted curved pipe. This mixing enhancement increases with β.
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Leonov, Sergey, Yury Isaenkov i Alexander Firsov. "Mixing Intensification in High-Speed Flow by Unstable Pulse Discharge". W 40th AIAA Plasmadynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2009. http://dx.doi.org/10.2514/6.2009-4074.
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Kockmann, Norbert, i Alexander Holbach. "Microchannel Device for Droplet Generation, Mixing, and Phase Separation for Continuous Counter-Current Flow Extraction". W ASME 2013 11th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/icnmm2013-73106.
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Process intensification is a major goal in chemical engineering, which is often obtained by miniaturized devices with enhanced heat and mass transfer characteristics. This work shows a microchannel device for liquid-liquid extraction and reactions with integrated droplet generation, enhanced mixing and phase separation. Monodisperse droplets with diameters in the range from 0.3 to 0.7 mm are generated by co-current jet flow with different operating modes of aqueous and organic phase. Flow regime maps indicate operation conditions for small and monodisperse droplets of the organic phase. A glass plate with a single microstructured channel serves for sufficient residence time and intensive mixing between the two phases. At the outlet, a wider channel leads to droplet coalescence and agglomeration at a hydrophobic wall and outlet tube for the organic phase. A complete phase separation was possible over a wide range of flow rates. The closed channel setup of droplet generation, mixing and phase equilibrium, and finally phase separation allows for countercurrent switching of the plates. This arrangement needs additional pumps to overcome the pressure drop over the plates, at least one pump more than the number of plates.
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Anand, Nadish, i Richard Gould. "Characterizing Heat Transfer Enhancement in Ferrofluid 2-D Channel Flows Using Mixing Numbers". W ASME 2021 Heat Transfer Summer Conference collocated with the ASME 2021 15th International Conference on Energy Sustainability. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/ht2021-63795.
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Abstract Ferrofluid channel flows have been used for many non-invasive flow manipulation applications, including drug-delivery, heat transfer enhancement, mixing enhancement, etc. Heat transfer enhancement is one of the most coveted outcomes from novel cooling systems employed for electronic cooling. While using Ferrofluids for heat transfer enhancement, the external magnetic field usually induces Kelvin Body Force, which causes the ferrofluid to swirl or ‘mix’. This mixing process causes extra convection over what is induced through fluid inertia and is responsible for heat transfer enhancement. In order to understand the phenomenon of heat transfer enhancement, it would be logical to view it from the perspective of mixing enhancement. Moreover, channel flows are most common in liquid cooling of electronics equipment, and hence such a fundamental understanding of synergies between mixing and heat transfer enhancement can help pose design rules for advanced cooling configuration for electronics cooling. In this work, a Ferrofluid channel flow is analyzed in the presence of an external magnetic field. A 2-D 90° bend channel ferrofluid flow is considered, with a significant length scale of 0.01 m, where two external current-carrying wires provide an external magnetic field. An external inward heat flux of 1000 W/m2 is applied on the walls of the channel. The channel flow is studied numerically by varying different parameters relating to the external magnetic field and flow conditions. The ferrofluid used is considered magnetite based on water as the carrier fluid, and the properties of which are modeled using appropriate mixture models for nanofluids. The mixing induced in the flow is characterized by using two different mixing numbers based on the flow velocity. This type of characterization is analogous to characterizing flow turbulence. The heat transfer enhancement is characterized using Nusselt numbers. These non-dimensional numbers (mixing) are studied in congruence with the Nusselt number to understand the relationship between the mixing and heat transfer and draw comparative inferences with flow conditions without heat transfer enhancement. Finally, conclusions are drawn between the mixing & heat transfer intensification at local and global levels and choosing the apposite mixing numbers to characterize heat transfer enhancement.
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Kockmann, Norbert. "Micro Process Engineering: Actual State and Challenges". W ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96023.
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For process industries the enhanced performance of key processes is crucial for their economical development. The process intensification benefits from the miniaturization of channels and conduits within devices, where the characteristic lengths are reaching into the order-of-magnitude of boundary layers or transport lengths. The fast transport rates can be used for many different purposes like fast and mixing sensitive reactions, temperature homogenization or nanoparticle precipitation. This review gives an overview of miniaturization effects and beneficial phenomena in microchannels with characteristic dimension from 10 to 1000 μm. Actual research projects in Germany in the Microsystems Technology program 2004–2009 are described as well as the actual EU projects. Further emphasis is laid on industrial projects in Europe, in the States and in Far East for laboratory or production purposes. Characteristic examples illustrate the first successful applications, the crucial drawbacks, but also the needs and demands for future research and development. The integration of micro structured devices together with sensing and actuating elements as well as with the “macro world” will be one of the key issues for the future development.
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Lasbet, Yahia, Bruno Auvity, Cathy Castelain i Hassan Peerhossaini. "Laminar Mixing, Heat Transfer and Pressure Losses in a Chaotic Mini-Channel: Application to the Fuel Cell Cooling". W ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96186.
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Currently, the heat exchangers allowing the cooling of the low temperature fuel cells (PEMFC) are integrated in the bipolar plates and constituted of a network of straight channels. The flow regime is laminar, and thus, unfavorable to an intense convective heat transfer. In order to increase the power density of the fuel cells, the use of chaotic geometries in the cooling system is envisaged to intensify high convective heat transfer. In this numerical study, several chaotic three-dimensional mini-channels of rectangular section (2 millimeters × 1 millimeter) are evaluated in terms of heat transfer efficiency, mixing properties and pressure losses. Their performances are compared to those of a straight channel geometry currently used in the cooling systems of the PEMFC, and a serpentine 2-D channel. Hydrodynamic and thermal performances of these geometries are computed using the commercial CFD code Fluent©. At the inlet section, the velocity profile is hydrodynamically established. The thermophysical properties of the fluid are constant and equal to those of water at 300 K. The Nusselt number is evaluated for a Reynolds number equal to 200 and with a uniform density flux imposed on the walls and equal to 10,000 W/m2. For the calculation of the mixing rate, a condition of adiabatic wall is imposed. The inlet section is horizontally divided into two parts. Water in the higher part is at the temperature of 320K and in the lower part is at the temperature of 300K. The calculation of the mixing rate is made for Reynolds numbers equal to 100 and 200. The present study shows that a 3-D chaotic channel geometry significantly improves the convective heat transfer compared to regular straight or serpentine channels. Among all the studied geometries, one of them induces the higher heat transfer intensification (mean Nusselt number equal to 20) with a strong pressure loss. With an alternative geometry, we obtained a better compromise between high heat transfer and reduced pressure loss. However, all the chaotic geometries present similar mixing rate for the two studied Reynolds number. To confirm the performances of the selected geometries, an experimental study is currently undertaken. The final aim is to realize and test a prototype of chaotic heat exchanger in a bipolar plate of PEMFC.
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Nazukin, Vladislav A., i Valery G. Avgustinovich. "CFD Analysis of Swirling Flows in Premixers". W ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25785.
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At present, the key element of lean low NOx combustors is a premixer where swirlers are often used for intensification of mixing processes and further formation of required flow pattern in combustor liner. Swirling flow leads to significant effect of some parts of hardware on stream features and mixing quality, emergence of flashback and flame blowout, formation of complex eddy structures causing flow perturbations. Therefore, at design phase, it is necessary to pay great attention to aerodynamics of premixers. The most effective method of swirling flow analysis in real combustor design is computational fluid dynamics (CFD). The present work is dedicated to study the effect of some computational model parameters, such as a turbulence model, grid size on calculation results as well as the analysis of the flow pattern in real swirler. Comparison between the analysis and experimental data showed that use of Detached Eddy Simulation (DES) allows to defining flow structure more accurately rather than use of RANS (URANS) with SST turbulence model also the size of computational grid elements influences stability of vortex structures. Analysis of swirling flow in production combustor swirler showed presence of large number of different eddy structures that can be conditionally divided into three types relative to its location of origin and a propagation path. Further, features of each eddy type were subsequently defined. Comparison of calculated and experimental pressure fluctuations spectrums verified correctness of computations. It was also noted that for the studied construction there is not even qualitative agreement between the steady and the time-averaged results of unsteady computations.
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Pioro, L. S., i I. L. Pioro. "High Efficiency Combined Aggregate – Submerged Combustion Melter–Electric Furnace for Vitrification of High-Level Radioactive Wastes". W 12th International Conference on Nuclear Engineering. ASMEDC, 2004. http://dx.doi.org/10.1115/icone12-49298.
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It is well known that high-level radioactive wastes (HLRAW) are usually vitrified inside electric furnaces. Disadvantages of electric furnaces are their low melting capacity and restrictions on charge preparation. Therefore, a new concept for a high efficiency combined aggregate – submerged combustion melter (SCM)–electric furnace was developed for vitrification of HLRAW. The main idea of this concept is to use the SCM as the primary high-capacity melting unit with direct melt drainage into an electric furnace. The SCM employs a single-stage method for vitrification of HLRAW. The method includes concentration (evaporation), calcination, and vitrification of HLRAW in a single-stage process inside a melting chamber of the SCM. Specific to the melting process is the use of a gas-air or gas-oxygen-air mixture with direct combustion inside a melt. Located inside the melt are high-temperature zones with increased reactivity of the gas phase, the existence of a developed interface surface, and intensive mixing, leading to intensification of the charge melting and vitrification process. The electric furnace clarifies molten glass, thus preparing the high-quality melt for subsequent melt pouring into containers for final storage.
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Terekhov, V. I., i N. I. Yarygina. "Heat Transfer in Separated Flows at High Levels of Free-Stream Turbulence". W 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-22154.
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In the present paper, a comparative analysis of the influence of free-stream turbulence on the separated flows past obstacles is given. As the obstacles, a downward-facing step, a flat rib installed at different orientations to the free-stream direction, a system of several ribs, and a cross-flow trench with vertical or inclined walls are considered. The experimental results obtained in the present study are compared to data previously reported by other workers. The structure of the separated flow at an enhanced level of free-stream turbulence is compared to the flow under low-turbulence conditions in terms of the characteristic length of the separation zone, mixing-layer parameters, and pressure distributions. The emphasis is on the thermal characteristics, including the profiles of temperature across the shear layer, the distributions of temperature over the streamlined surface, and the local and mean heat-transfer coefficients. It is shown that the effect of enhanced free-stream turbulence on the separated flow is much more pronounced than that on the boundary-layer flow over a flat surface. For separated flow, this effect is manifested more clearly behind rib than behind step. The largest heat-transfer intensification ratios due to external turbulence were found in the cross-flow trench and in the system of ribs.