Reactive Transport Modeling Approach And Its Initial Saltcake Dilution Chemical Modeling

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Reactive Transport Modeling Approach And Its Initial Saltcake Dilution Chemical Modeling

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Author : Yasuo Onishi
language : en
Publisher:
Release Date : 2002

Reactive Transport Modeling Approach And Its Initial Saltcake Dilution Chemical Modeling written by Yasuo Onishi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with categories.

Government Reports Announcements Index

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Author :
language : en
Publisher:
Release Date : 1996

Government Reports Announcements Index written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Science categories.

Exposure Time Formulation For Reactive Transport

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Author : Deviyani Gurung
language : en
Publisher:
Release Date : 2020

Exposure Time Formulation For Reactive Transport written by Deviyani Gurung and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with Chemical reactions categories.

Reactive transport modeling is an important tool for the analysis of physical, chemical and biological processes encountered in many environmental systems. Several upscaled models, of natural or engineered porous media, are commonly used for such modeling and take advantage of standard advection dispersion reaction equations (ADREs). These simple models are however unable to account for physical processes that can heavily influence reactive transport in such media, such as pre-asymptotic flow fields and mixing limitations between transport and reaction processes. To account for these complexities, researchers have developed proportionally complex mathematical and simulation-based models. However, these complicated models have remained underutilized among most practitioners owing to their non-intuitive formulations and computationally intensive mathematics. In this thesis, we present a novel, intuitive and relatively less strenuous computational method for the simulation of homogenous chemical reactions through the use of age: defined as exposure-time to the flow field, structured ADREs.The utility of this method is demonstrated through the development of two models to quantify mixing processes and pre-asymptotic dispersion without the use of non-local models. Analysis of reactive transport in porous media has benefited from the concept of mixing ratios, in particular as a basis for mathematical separation of different species and processes. Additionally, general use of solute age has been recently explored as a proxy for reaction extent. Pairing these two concepts we developed mixing ratio models, structured on age, that is cast into a 1D transport formulation and compared with conventional formulations of mixing ratio models. This modeling framework was applied to the problem of mixing-limited reactive transport in one-dimension by explicitly considering unmixed and mixed phases. To address mixing limitations under the entirety of transport, including the pre-asymptotic dispersion timeframe, I use age-dependent dispersion coefficient in a local-formulation of transport. This formulation addresses the divisive controversy surrounding the use of time-dependent dispersion coefficients within an ADRE framework. Our physically intuitive model matches the performance of a recently published complicated and computationally intensive model of transient dispersion in direct comparison. Furthermore, our solutions can be applied to other upscaled one-dimensional transport problems such as river corridor, pipe networks, groundwater flows.

Upscaling Mixing Limited Chemical Reactions From Pore To Continuum Scale Using The Dispersive Lamella Concept

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Author : Lazaro J. Perez Fonseca
language : en
Publisher:
Release Date : 2020

Upscaling Mixing Limited Chemical Reactions From Pore To Continuum Scale Using The Dispersive Lamella Concept written by Lazaro J. Perez Fonseca and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020 with categories.

Reactive transport modeling is an important tool for the analysis of coupled physical, chemical, and biological processes in Earth systems. Observed reactive transport in heterogeneous porous media shows a different behavior than the established transport laws for homogeneous media. Natural aquifers exhibit physical and chemical heterogeneities at all scales, which leads to reaction and transport dynamics that cannot be explained by traditional reactive models based on the advection-dispersion-reaction equation (ADRE). In particular, the discrepancy is traced back to the nonuniform nature of flow velocity fields, complex spatial concentration distributions, and the degree of mixing between reactants. The role and contribution of these factors is key to provide accurate predictions of reactions. The complexity of the task lies in the enormous range of spatial and temporal scales that reactants find in natural porous media. Hence, the complete characterization of the fate of chemical reactions requires that models accounts for the basic mechanisms that govern the mixing and reaction dynamics. In this thesis, we present a novel methodology for the simulation of homogeneous chemical reactions. The proposed methodology is a random walk particle tracking approach (RWPT) coupled with reactions that simulates bimolecular chemical reactions, and is equivalent to the ADRE. Reactions among particles are determined by a reaction probability given in terms of the reaction rate coefficient, the total number of particles, and an interaction radius that describes a well-mixed support volume at which all particles have the same probability to react. The method is meshless and free of numerical dispersion. The RWPT approach is validated against analytical solutions for different flow scenarios under slow and fast reaction kinetics. We focus on the impact of the mixing degree between chemical species and its role in the global reaction behavior. We first consider a reactive displacement in a Poiseuille flow through a pore channel, this system allow us to quantify the impact of the interaction of interface deformation and diffusion on mixing and reactive transport. We observe overestimation of the global reaction efficiency by the use of the Taylor dispersion coefficient at preasymptotic times, when the system is characterized by incomplete mixing. Next, we observe features of incomplete mixing in a synthetic porous medium. Results show that macroscopic predictions using the hydrodynamic dispersion coefficient overestimates the amount of reaction. In addition, we analize the bimolecular reactive transport in a laboratory experiment, where we find that the amount of reaction is affected by the amount of mixing due to difusion, the amount of mixing due to spreading and the degree of heterogeneity of the flow field. The contributions of these factors induces that ADRE estimation of the total reaction product fails. In order to characterize incomplete mixing and provide an explicit relation between fluid deformation and its impact on the temporal evolution of the chemical reactivity, we develop the dispersive lamella approach based on the concept of effective dispersion which accurately predicts the full evolution of the product mass. Specifically, the approach captures the impact of interface deformation and diffusive coalescence. Using this methodology, we quantify the impact of flow heterogeneities on the amount of fluid mixing in a pore channel, where we observe three temporal regimes based on the production rate of the product mass. In addition, the dispersive lamella predictions capture the kinetics of the reaction in a synthetic porous medium. Results reveal that reaction behavior is controlled by the interface front between the two reactants. In the pore-scale experimental visualization, the dispersive lamella show that reaction is controlled by the deformed mixing interface at early times, and for fingering coalescence at late times.

First Order Kinetics Controlled Multiple Species Reactive Transport Of Dissolved Organic Compounds In Groundwater

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Author :
language : en
Publisher:
Release Date : 1990

First Order Kinetics Controlled Multiple Species Reactive Transport Of Dissolved Organic Compounds In Groundwater written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.

Reactive chemical transport models developed over the past decade have generally relied on the assumption that local thermodynamic equilibrium is achieved at all times between aqueous species in a given system. Consequently, homogeneous aqueous systems characterized by a number of kinetically slow reactions, particularly problems involving organic species, cannot be satisfactorily modeled. In this study, we present a prototype computer model, KINETRAN, which is designed to handle kinetically-controlled homogeneous reactions in the aqueous phase, along with the transport of the various species involved, through geologic media. 31 refs., 53 figs., 10 tabs.

Coupled Modeling Of Non Isothermal Multiphase Flow Solutetransport And Reactive Chemistry In Porous And Fractured Media

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Author :
language : en
Publisher:
Release Date : 1998

Coupled Modeling Of Non Isothermal Multiphase Flow Solutetransport And Reactive Chemistry In Porous And Fractured Media written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.

Coupled modeling of subsurface multiphase fluid and heat flow, solute transport and chemical reactions can be used for the assessment of acid mine drainage remediation, mineral deposition, waste disposal sites, hydrothermal convection, contaminant transport, and groundwater quality. Here they present a numerical simulation model, TOUGHREACT, which considers non-isothermal multi-component chemical transport in both liquid and gas phases. A wide range of subsurface thermo-physical-chemical processes is considered. The model can be applied to one-, two- or three-dimensional porous and fractured media with physical and chemical heterogeneity. The model can accommodate any number of chemical species present in liquid, gas and solid phases. A variety of equilibrium chemical reactions is considered, such as aqueous complexation, gas dissolution/exsolution, cation exchange, and surface complexation. Mineral dissolution/precipitation can proceed either subject to local equilibrium or kinetic conditions. The coupled model employs a sequential iteration approach with reasonable computing efficiency. The development of the governing equations and numerical approach is presented along with the discussion of the model implementation and capabilities. The model is verified for a wide range of subsurface physical and chemical processes. The model is well suited for flow and reactive transport in variably saturated porous and fractured media. In the second of this two-part paper, three applications covering a variety of problems are presented to illustrate the capabilities of the model.

Process Modeling Simulation And Environmental Applications In Chemical Engineering

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Author : Bharat A. Bhanvase
language : en
Publisher: CRC Press
Release Date : 2016-10-14

Process Modeling Simulation And Environmental Applications In Chemical Engineering written by Bharat A. Bhanvase and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-10-14 with Science categories.

In this valuable volume, new and original research on various topics on chemical engineering and technology is presented on modeling and simulation, material synthesis, wastewater treatment, analytical techniques, and microreactors. The research presented here can be applied to technology in food, paper and pulp, polymers, petrochemicals, surface coatings, oil technology aspects, among other uses. The book is divided into five sections: modeling and simulation environmental applications materials and applications processes and applications analytical methods Topics include: modeling and simulation of chemical processes process integration and intensification separation processes advances in unit operations and processes chemical reaction engineering fuel and energy advanced materials CFD and transport processes wastewater treatment The valuable research presented here will be of interest to researchers, scientists, industry practitioners, as well as upper-level students.

Modeling Of Process Intensification

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Author : Frerich J. Keil
language : en
Publisher: John Wiley & Sons
Release Date : 2007-04-09

Modeling Of Process Intensification written by Frerich J. Keil and has been published by John Wiley & Sons this book supported file pdf, txt, epub, kindle and other format this book has been release on 2007-04-09 with Technology & Engineering categories.

Combining the knowledge involved in process engineering and process modeling, this is the first book to cover all modeling methods applicable to process intensification. Both the editors and authors are renowned experts from industry and academia in the various fields of process modeling and integrated chemical processes. Following an introduction to the topic, the book goes on to look at equipment and operational methods, monolithic catalysis, HEX, micro- and reverse flow reactors, catalytic and reactive distillation, the simulated-moving bed and vibration bubble column as well as ultrasound and ultrasonic reactors. A final chapter is devoted to processes under supercritical conditions. In its treatment of hot topics of multidisciplinary interest, this book is of great value to researchers and engineers alike.

Reactive Transport In Natural Porous Media

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Author : Babak Shafei
language : en
Publisher:
Release Date : 2012

Reactive Transport In Natural Porous Media written by Babak Shafei and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012 with Biogeochemistry categories.

Reactive Transport Models (RTMs) provide quantitative tools to analyze the interaction between transport and biogeochemical processes in subsurface environments such as aquatic sediments and groundwater flow. A tremendous amount of research has shown the role and impact of scaling behavior of the reactive systems which stems from geologic heterogeneity. Depending on the kinetics of the reactions, different types of formulations have been proposed to describe reactions in RTMs. We introduce a novel quantitative criteria on the range of validity of local equilibrium assumption (LEA) in aquatic sediments with irreversible heterogeneous sorption reactions. Then we present a one-dimensional (1-D) early diagenetic module, MATSEDLAB, developed in MATLAB. The module provides templates for representing the reaction network, boundary conditions and transport regime, which the user can modify to fit the particular early diagenetic model configuration of interest. We describe the theoretical background of the model and introduce the MATLAB pdepe solver, followed by calibration and validation of the model by a number of theoretical and empirical applications. Finally, we introduce a new pore-scale model using lattice Boltzmann (LB) approach. It uses an iterative scheme for the chemical transport-reaction part and recent advances in the development of optimal advection-diffusion solvers within the lattice Boltzmann method framework. We present results for the dissolution and precipitation of a porous medium under different dynamical conditions, varying reaction rates and the ratio of advective to diffusive transport (Pe, Peclet number) for linear reactions. The final set of calculations considers sorption reactions on a heterogeneous porous medium. We use our model to investigate the effect of heterogeneity on the pore-scale distribution of sorption sites and the competition between three different sorption reactions.

Reactive Transport Modeling In The Geosciences

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Author : Lauren Browning
language : en
Publisher:
Release Date : 2003

Reactive Transport Modeling In The Geosciences written by Lauren Browning and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Geochemical modeling categories.