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Journal ArticleDOI

Modelling of direct-contact evaporation using a simultaneous heat and multicomponent mass-transfer model for superheated bubbles

TL;DR: In this paper, a model for coupled heat and mass transfer in binary systems during the formation and ascension of superheated bubbles was extended to a multicomponent system comprising N volatile species.
About: This article is published in Chemical Engineering Science.The article was published on 2005-03-01. It has received 10 citations till now. The article focuses on the topics: Mass transfer & Heat transfer.
Citations
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Journal ArticleDOI
TL;DR: In this paper, a review of the literature regarding gas-liquid direct contact evaporators is presented, addressing classic and potential applications, bubble regimes, gas holdup and bubble size distributions, as well as mathematical models proposed for simulating the unit.
Abstract: Gas-liquid direct-contact evaporators are characterized by the bubbling of a superheated gas through the solution to be concentrated. In other words, they are nonisothermal bubble columns. Despite their simplicity of construction, these units exhibit rather complex hydrodynamics and, similar to what occurs to isothermal bubble columns, the design of such units still poses a problem. The present paper reviews the literature regarding this kind of equipment, addressing both experimental studies and modeling efforts. The covered issues include classic and potential applications, bubbling regimes, gas holdup and bubble size distributions, as well as mathematical models proposed for simulating the unit. Additionally, pertinent literature on isothermal bubble columns is also discussed. Recommendations are made for future research.

57 citations

Journal ArticleDOI
TL;DR: In this paper, a quantitative criterion was developed to compute the critical velocity for bubble coalescence based on the relative velocities and the outcome (coalescence or bouncing) of the recorded collisions.

46 citations

Journal ArticleDOI
TL;DR: In this paper, a numerical study has been performed to determine evaporation rate from the surface of ethanol/iso-octane in an inclined 2D channel, where liquid and gas phases are flowing in counter-current direction.

40 citations

Journal ArticleDOI
TL;DR: In this article, the performance of bubble breakage and coalescence models in bubble column simulations was evaluated using experimental data of bubble size distributions for the air-water system in an isothermal bubble column.

26 citations

Journal ArticleDOI
TL;DR: In this paper, a computational model of a single gas microbubble immersed in a liquid of ethanol-water mixture is developed and solved numerically, which complements earlier binary distillation experiments in which the ethanol mixture is stripped by hot air microbubbles achieving around 98% vol. ethanol from the azeotropic mixture.
Abstract: A computational model of a single gas microbubble immersed in a liquid of ethanol–water mixture is developed and solved numerically. This complements earlier binary distillation experiments in which the ethanol–water mixture is stripped by hot air microbubbles achieving around 98% vol. ethanol from the azeotropic mixture. The proposed model has been developed using Galerkin finite element methods to predict the temperature and vapor content of the gas microbubble as a function of its residence time in the liquid phase. This model incorporates a novel rate law that evolves on a time scale related to the internal mixing of microbubbles of 10–3s. The model predictions of a single bubble were shown to be in very good agreement with the existing experimental data, demonstrating that the ratio of ethanol to water in the microbubble regime are higher than the expected ratios that would be consistent with equilibrium theory for all initial bubble temperatures and all liquid ethanol mole fractions considered and w...

20 citations

References
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Book
01 Jan 1980
TL;DR: In this article, the authors focus on heat and mass transfer, fluid flow, chemical reaction, and other related processes that occur in engineering equipment, the natural environment, and living organisms.
Abstract: This book focuses on heat and mass transfer, fluid flow, chemical reaction, and other related processes that occur in engineering equipment, the natural environment, and living organisms. Using simple algebra and elementary calculus, the author develops numerical methods for predicting these processes mainly based on physical considerations. Through this approach, readers will develop a deeper understanding of the underlying physical aspects of heat transfer and fluid flow as well as improve their ability to analyze and interpret computed results.

21,858 citations

Journal Article
01 Jun 1978
TL;DR: In this paper, the authors evaluated the applicability of the standard κ-ϵ equations and other turbulence models with respect to their applicability in swirling, recirculating flows.
Abstract: The standard κ-ϵ equations and other turbulence models are evaluated with respect to their applicability in swirling, recirculating flows. The turbulence models are formulated on the basis of two separate viewpoints. The first perspective assumes that an isotropic eddy viscosity and the modified Boussinesq hypothesis adequately describe the stress distributions, and that the source of predictive error is a consequence of the modeled terms in the κ-ϵ equations. Both stabilizing and destabilizing Richardson number corrections are incorporated to investigate this line of reasoning. A second viewpoint proposes that the eddy viscosity approach is inherently inadequate and that a redistribution of the stress magnitudes is necessary. Investigation of higher-order closure is pursued on the level of an algebraic stress closure. Various turbulence model predictions are compared with experimental data from a variety of isothermal, confined studies. Supportive swirl comparisons are also performed for a laminar flow case, as well as reacting flow cases. Parallel predictions or contributions from other sources are also consulted where appropriate. Predictive accuracy was found to be a partial function of inlet boundary conditions and numerical diffusion. Despite prediction sensitivity to inlet conditions and numerics, the data comparisons delineate the relative advantages and disadvantages of the various modifications. Possible research avenues in the area of computational modeling of strongly swirling, recirculating flows are reviewed and discussed.

5,396 citations

Book
25 May 1984
TL;DR: An overview of diffusion and separation processes brings unsurpassed, engaging clarity to this complex topic as mentioned in this paper, which is a key part of the undergraduate chemical engineering curriculum and at the core of understanding chemical purification and reaction engineering.
Abstract: This overview of diffusion and separation processes brings unsurpassed, engaging clarity to this complex topic. Diffusion is a key part of the undergraduate chemical engineering curriculum and at the core of understanding chemical purification and reaction engineering. This spontaneous mixing process is also central to our daily lives, with importance in phenomena as diverse as the dispersal of pollutants to digestion in the small intestine. For students, Diffusion goes from the basics of mass transfer and diffusion itself, with strong support through worked examples and a range of student questions. It also takes the reader right through to the cutting edge of our understanding, and the new examples in this third edition will appeal to professional scientists and engineers. Retaining the trademark enthusiastic style, the broad coverage now extends to biology and medicine.

5,195 citations

Book
01 Jan 1986
TL;DR: In this article, Rankine and Hughes-Hugoniot relations of Detonation and Deflagration Waves of Premixed Gases and Turbulent Reacting Flows with Premixed Reactants.
Abstract: Review of Chemical Thermodynamics. Review of Chemical Kinetics. Conservation Equations for Multi--Component Reacting Systems. Rankine--Hugoniot Relations of Detonation and Deflagration Waves of Premixed Gases. Premixed Laminar Flames. Diffusion Flames and Combustion of a Single Liquid Fuel Droplet. Turbulent Flames. Turbulent Reacting Flows with Premixed Reactants. Chemically Reacting Boundary--Layer Flows. Ignition. Appendix. Index.

1,990 citations

Journal ArticleDOI
TL;DR: In this paper, the authors measured the interfacial area in gas-liquid dispersions and correlated the data with other published data for heat and mass transfer in liquid-liquid and solid-gas dispersions in which the dispersed phases are free to move under the action of gravity.

742 citations