Coupled reaction-transport model

Morrison, S. J., Tripathi, V. S. Spangler, R. R. 1995. Coupled reaction/transport modeling of a chemical barrier for controlling uranium (VI) contamination in groundwater. Journal of Contaminant Hydrology, 17, 347-363. 

The coupled reaction transport modeling effort provided a few insights for the design of remedial action. It was found that ... 

Morrison et al. (1995) investigated the adsorption of on ferrihydrite and coupled the data with a reaction/transport model for contaminated groundwater which included economic factors. 

Equations (19)-(24) completely define the CO/H2 reaction-transport model by describing reactant concentrations within catalyst pellets and along the reactor position. They also form a system of coupled ordinary equations and boundary value problems in the unknowns x and y the equivalent dimensional form and details about its numerical solution can also be found elsewhere (4,5). 

At the Eotvos Lorand University - Department of Chemical Technology and Environmental Chemistry, a coupled Eulerian photochemical reaction-transport model and a detailed ozone dry-deposition model for the investigation of ozone fluxes over Hungary have been developed and are used in collaboration with Leeds University of the UK. As part of a research project with Ghent University, aerosol samples were collected using several filter-based devices (Nuclepore polycarbonate membrane. Teflon membrane and quartz fibre filters) over... 

Figure 10.6. Breakthrough curves for sulfate at the 200th cell from (a) the coupled reactive transport model (surface adsorption reactions are added) and (b) the d-based model.

While the mechanistic treatment of chemical reactions in the coupled multi-component, multi-species mass transport has obvious advantages over the empirical isotherm-based transport models, we can also easily compile a long list of shortcomings for coupled reactive transport models. We choose a few and list them here. 

Since publication of the first edition, the held of reaction modeling has continued to grow and hnd increasingly broad application. In particular, the description of microbial activity, surface chemistry, and redox chemistry within reaction models has become broader and more rigorous. Reaction models are commonly coupled to numerical models of mass and heat transport, producing a classification now known as reactive transport modeling. These areas are covered in detail in this new edihon. 

At the same time, reaction modeling is now commonly coupled to the problem of mass transport in groundwater flows, producing a subfield known as reactive transport modeling. Whereas a decade ago such modeling was the domain of specialists, improvements in mathematical formulations and the development of more accessible software codes have thrust it squarely into the mainstream. 

Stimulated by nature and in particular by the idea of modelling biotic coupled reaction systems such as ion transport and oxidative phosphorylation, recent attention has focused on a new generation of abiotic host... 

In this chapter, we will review the fundamental models that we developed to predict cathode carbon-support corrosion induced by local H2 starvation and start-stop in a PEM fuel cell, and show how we used them to understand experiments and provide guidelines for developing strategies to mitigate carbon corrosion. We will discuss the kinetic model,12 coupled kinetic and transport model,14 and pseudo-capacitance model15 sequentially in the three sections that follow. Given the measured electrode kinetics for the electrochemical reactions appearing in Fig. 1, we will describe a model, compare the model results with available experimental data, and then present... 

The most sophisticated models applied to FePRBs to date combine multiple ADEs (i.e., multicomponent transport) with coupled chemical reactions [184,186,208]. These multicomponent reactive transport models were used to simulate the geochemical evolution in FePRBs for the treatment of TCE [184] and for remediating mixtures of Cr(VI) and chlorinated solvents [186,208]. The models are capable of reproducing the spatial distribution of field-observable parameters such as the concentrations of the chlorinated solvents, pH, Eh, alkalinity, Mg2 +, S042-, and N03 ... 

Figure 5.6 Biogeochemical processes affecting their flux rates across the air-water interface of the four biogases (N2O, O2, CO2, NH3) analyzed in a full transient, one-dimensional reactive transport CONTRASTE model (Coupled, networked, transport-reaction algorithm for strong tidal estuaries) for the Scheldt estuary (The Netherlands) (Modified from Vanderborght et al., 2002.)...

Enzyme-catalyzed reactions, including the electron transport chain and proton translocation, are composed of series of elementary reactions that proceed forward and backward. One of the methods in describing this thermodynamically and mathematically coupled complex chemical reaction-transport system is the nonequilibrium thermodynamic model, which does not require the detailed knowledge of the system. 

Many biochemical signaling processes involve the coupled reaction diffusion of two or more substrates. Metabolic biochemical pathways are mainly multicomponent reaction cycles leading to binding and/or signaling and are coupled to the transport of substrates. A reaction-diffusion model can also describe the diffusion of certain proteins along the bacterium and their transfer between the cytoplasmic membrane and cytoplasm, and the generation of protein oscillation along the bacterium (Wood and Whitaker, 2000). 

The permeate is continuously withdrawn through the membrane from the feed sueam. The fluid velocity, pressure and species concentrations on both sides of the membrane and permeate flux are made complex by the reaction and the suction of the permeate stream and all of them depend on the position, design configurations and operating conditions in the membrane reactor. In other words, the Navier-Stokes equations, the convective diffusion equations of species and the reaction kinetics equations are coupled. The transport equations are usually coupled through the concentration-dependent membrane flux and species concentration gradients at the membrane wall. As shown in Chapter 10, for all the available membrane reactor models, the hydrodynamics is assumed to follow prescribed velocity and sometimes pressure drop equations. This makes the species transport and kinetics equations decoupled and renders the solution of... 

Reactive solute-transport models couple the equations that describe physical transport processes with equations that describe geochemical reactions. These models can be divided into three basic categories (i) equilibrium models, (ii) partial equilibrium models, and (iii) kinetic models. The three are differentiated by the... 

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