A model is successfully developed using COMSOL Multiphysics. The validated model is used to study the enhancement influence of chemical reactions on the ...
COMSOL Conference 2008 Presentation ( World wide )
Chemical Process Chemical Reaction
本書類に掲載の事例は、全て COMSOL Conference 2008 world wide 版 CD にプレゼンテーション資料や論文等が収録さ れております。CD には、他様々な分野の発表約 300 の事例が掲載されております。（収録内容は、東京開催時の発表以外主に英文で の発表となっております。）
： Study of the CO2 Transfer Rate in a Reacting Flow for the Refined Sodium Bicarbonate Production Process C. Wylock1, A. Larcy1, P. Colinet1, T. Cartage2, and B. Haut1 1Université Libre de Bruxelles, Brussels, Belgium 2Solvay S.A., Brussels, Belgium This work deals with the quantification of the CO2 transfer rate from a bubble to the surrounding liquid in a bubble column. A model is successfully developed using COMSOL Multiphysics. The validated model is used to study the enhancement influence of chemical reactions on the transfer rate. Moreover, the results of this study are compared with a classical 1-D approach and excellent comparison is observed.
Surface concentration fields of a species for both fully contaminated (left) and clean (right) bubbles.
Simulation of Surface Chemical Reactions in a Monolith Channel for Hydrogen Production N. Pacheco1, D. Pavone1, K. Surla1, J. Houzelot2, and E. Schaer2 1IFP-Lyon, Solaize, France 2ENSIC, Solaize, France This paper intends to show a model of a monolithic reactor for the autothermal reforming process (ATR), a process that uses hydrocarbons to produce H2. The ATR chemical reactions take place on the surface of monolith channels coated with a catalyst. The isothermal ATR reactor is modeled using 42 catalytic surface chemical reactions that involve 13 solid species and 7 gas species. To solve the model, two numerical techniques with COMSOL are compared: the Surface Model using weak form equations (SM) and a standard thin Volume Model (VM). This paper shows that the surface modeling (SM) is the better way to calculate the monolith catalytic reactions.
Concentration profiles in the monolith channel.
：Use of COMSOL Multiphysics to develop a comprehensive, user-friendly predictive tool for food safety and quality A. Halder1, A. Datta1, G. Black2, and P. Davidson2 1Biological and Environmental Engineering, Cornell University, Ithaca, NY, USA 2Department of Food Science, University of Tennessee, Knoxville, TN, USA The objective is to integrate the most powerful and versatile fundamental-based simulation of food processes with the best known prediction models available for microbiological growth and inactivation to provide a tool that predicts the safety and risk parameters for different thermal food processes. The software allows decision-making and problem solving for food-safety researchers, extension personnel and regulators. Process models for thermal food processes have been developed using COMSOL Multiphysics. The process simulations are integrated with various databases such as USDA composition database to get the composition of food, a food property database and a chemical and microbiological growth/death kinetics database.
Amit Halder(left) receives the Popular Choice Best Poster Award from COMSOL Inc. CEO Svante Littmarck at the COMSOL Conference 2008 Boston.
：Study of a Self Heating Process of Tetrafluoroethylene by the Exothermic Dimerization Reaction to Octafluorocyclobutane M. Beckmann-Kluge1, H. Krause1, V. Schröder1, A. Acikalin2, and J. Steinbach2 1Federal Institute for Materials Research and Testing, Berlin, Germany 2Technical University Berlin, Berlin, Germany The self heating process of Tetrafluoroethylene caused by an exothermic dimerization reaction was studied. The heat of reaction can lead to a thermal explosion by the decomposition of the Tetrafluoroethylene. Different reaction kinetics, including multistep kinetics, were used to describe the mass balance. The COMSOL Chemical Engineering Module was used to perform the simulation which was validated by experiments and yielded well-correlating results.
Temperature and flow field in a 3-dm³ vessel.
：Integrating COMSOL into a Mathematical Modeling Course for Chemical Engineers A. Dixon, and D. DiBiasio Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA, USA The multiphysics simulation package COMSOL was incorporated into a course in mathematical modeling for chemical engineers. Our implementation for the first year of using COMSOL in the course is described, and assessment results based on examinations and student survey results are presented and analyzed. The students appear to be learning how to operate the COMSOL program quite satisfactorily, but their skills in setting up problems and in becoming discriminating users of the technology are less well developed and will motivate some changes in the curriculum for the next offering. Sample student solutions to the in-lab midterm computer exam.
： バイオエタノールを燃料にした非平衡操作による水素製造に関する研究 教授 亀山秀雄 様 東京農工大学 工学部化学システム工学科 The bio-ethanol-to-hydrogen system has the remarkable advantage of being nearly CO2 neutral, since the produced carbon dioxide is consumed for biomass growth, thus offering a nearly closed carbon loop. Due to equilibrium limitations, this process must be carried out at high temperature (up to 1073 K) which causes huge energy consumption. A transient simulation was carried out based on the reaction kinetics and adsorption-desorption mechanism. The simulation results showed that the favorable reaction temperature was shifted to 923 K and the outlet CO approached ppm order, which shows a rather good agreement with the experiment results. Based on the model, the reactor design parameters were also discussed.
CO2 concentration distribution in the reforming channel at (a) T=873 K, (b)T=823K and (c)T=723 K.
：Modeling the Behavior of Single Particle during Drying Process S. Bellur, B. Agasanpura, and C. Coronella Chemical and Metallurgical Engineering Department, University of Nevada, Reno, Nevada, USA The aim of the present work is the formulation of a computational model describing transport phenomena in transient biosolids drying. COMSOL Multiphysics was used to perform the simulations, with two spatial dimensions. After a time step of 0.1 s, we found that the solid reached thermal equilibrium with the surrounding gas, which is consistent with empirical correlations.
：Analysis of Heat, Mass Transport, and Momentum Transport Effects in Complex Catalyst Shapes for Gas-Phase Heterogeneous Reactions Using COMSOL Multiphysics A. Nagaraj1, and P. Mills2 1Department of Electrical Engineering and Computer Science, Texas A&M University, Kingsville, TX, USA 2Department of Chemical and Natural Gas Engineering, Texas A&M University, Kingsville, TX, USA The global demand for sulfuric acid has been forecast to grow at an average of 2.6% per year from 2005 – 2010. The primary objective of this work is to analyze the performance of various heterogeneous catalyst shapes that have been proposed for the oxidation of SO2 to SO3 used in the manufacture of sulfuric acid. COMSOL Multiphysics provides a powerful numerical platform for simulation of complex catalyst shapes. These models can be readily coupled to global reactor models that allow the performance of pilot and commercial scale adiabatic reactors to be analyzed with a detailed accounting of various complex hydrodynamic effects and transport-kinetics interactions.
Illustration of various catalyst shapes.
Magnetic Particle Buildup Growth on Single Wire in High Gradient Magnetic Separation F. Chen Department of Chemical Engineering, M.I.T., Cambridge, MA, USA Magnetic fluids containing nano or submicron magnetic particles and their application in food, biological and pharmaceutical systems have recently attracted increasing attention. Magnetic particles can be collected efficiently in magnetizable matrices (e.g. iron wires) in high gradient magnetic separation (HGMS) process. In this work, the dynamic buildup growth process is treated as a moving-boundary problem, in which the growing front of the buildup is tracked explicitly by marker points evenly distributed on its surface. The flow field and magnetic field are calculated using the finite element method (FEM). The simulation results with this dynamic model showed very good agreement with experimental results.
：COMSOL Multiphysics Models for Teaching Chemical Engineering Fundamentals: Absorption Column Models and Illustration of the Two-Film Theory of Mass Transfer W. Clark Chemical Engineering Department, Worcester Polytechnic Institute, Worcester, MA, USA COMSOL® models have been developed for teaching gas absorption fundamentals. Model results are compared to environmentally significant experimental results for removing CO2 and SO2 from air using water as solvent. For concentrated gas mixtures, the models are shown to be equivalent to but easier to use than the traditional graphical integration method and to a solution method developed with MATLAB®. A more detailed model has been developed that explicitly uses the two-film theory of mass transfer and illustrates the resistance to mass transfer due to the liquid and gas films and the physical significance of the mass transfer coefficient.
This image created with COMSOL Chemical Engineering Module shows the solution to a two-film absorber model visualizing the CO2 concentration.
：Mixing and Residence Time Distribution Studies in Microchannels with Floor Herringbone Structures A. Cantu-Perez, S. Ping Kee, and A. Gavriilidis University College London, Department of Chemical Engineering, Torrington Place, London, UK The mixing characteristics and residence time distributions (RTDs) of a staggered herringbone microchannel have been investigated numerically by COMSOL Multiphysics and by particle tracking algorithms that incorporate diffusion via a random walk. All simulations were validated with experimental data. It was found that for low Peclet numbers the use of herringbone structures have little impact on the RTD. However at higher Peclet numbers the herringbone channels have a narrower RTD than a rectangular channel. This opens the possibility of increasing the dimensions of the channel or the flowrate without compromising its performance in terms of RTD.
Comparison of mixing simulations with experimental data.
：Modeling of Behavior of Local Phase Separation in Electric Field 松本秀行様， 黒田千秋様 東京工業大学 大学院理工学研究科化学工学 We introduce a method for numerical simulation of phase separation & formation using AC electric field in catalytic reaction process. Then, application of system modeling is also presented as an efficient method of process design using simulation based on multiple physical models, e.g. electric current, N-S equation.
Surface color plot of the temperature distribution.
：Development of an Interlinked Curriculum Component Module for Microchemical Process Systems Components Using COMSOL Multiphysics A. Mokal, and P. Mills Department of Chemical and Natural Gas Engineering, Texas A&M University, Kingsville, TX, USA COMSOL Multiphysics provides a powerful numerical platform where various models for microchemical process technology components can be readily created for both education and research. This modeling tool allows chemical engineering students to focus on understanding the effects of various microchemical system component design and operational parameters versus coding and debugging of the numerical methods. The development of a user interface that works between the COMSOL engine and the student is also described. This interface minimizes the amount of time spent on setting up the problem while also keeping the problem specifications within reasonable bounds so that feasible solutions are obtained.
Temperature
distribution
for
counter-current
flow in a 3-D
MEMS heat-exchanger.
：COMSOL Multiphysics Modeling of Chloride Binding in Diffusive Transport of Chlorides in Concrete M.A. Shazali1, W.A. Al-Kutti2, M.K. Rahman3, A.H. Al-Gadhib2, and M.H. Baluch2 1INCO Precast Engineering, Industrial Contractors Co. Ltd., Al-Khobar, Saudi Arabia 2Department of Civil Engineering, King Fahd Univ. of Petroleum & Minerals, Saudi Arabia 3Research Institute, King Fahd Univ. of Petroleum & Minerals, Saudi Arabia One of the most revealing causes of deterioration leading to durability loss in concrete structures is premature time-to-corrosion ignition due to chloride induced corrosion associated with diffusive transport of chloride in concrete. The aim of this work is to demonstrate the capability of using COMSOL Multiphysics modeling to provide insight regarding a more realistic consideration of chloride penetration behavior in concrete in view of chloride binding. Simulations of the problem in COMSOL allow main process of the chloride binding to be closely captured in the light of its nonlinear concentration dependence and influence on evolution of chloride diffusivity governing the transport problem. Good agreement of the model results with experimental data was established to provide a basis for reasonable service life prediction in view of the time-to-corrosion initiation paradigm.
Comparison of Cf profiles with measured data.
： Ignition Process of Microplasmas H. Porteanu, and R. Gesche Ferdinand-Braun-Institut für Höchstfrequenztechnik, Berlin, Germany Microplasmas at atmospheric pressure are required in many applications, where treatments in normal ambient, with spatial resolution, are important. The interest on such miniaturized sources has increased due to the availability of a new generation of microwave sources based on high power GaN transistors. The present work deals with a simulation of the plasma formation after the application of the microwave power. The results are needed for the optimization of the GaN oscillator, directly coupled to the plasma source. The slot resonator used in the experiment is simulated by a 2D geometry representing two spatially, infinitely extended, parallel metallic plates. The self consistent calculations are performed using COMSOL Multiphysics.
Microplasma sources; COMSOL field simulations.
：Nanofiltration Modeling Based on the Extended Nernst-Planck Equation under Different Physical Modes J. Gozálvez-Zafrilla, and A. Santafé-Moros Department of Chemical and Nuclear Engineering, Universidad Politécnica de Valencia, Valencia, Spain The most successful nanofiltration models are those based on the combination of the Extended Nernst-Planck equation with the Donnan steric equilibrium. These models have been typically solved by using iterative procedures based on the Runge-Kutta method. Yet, such procedures present convergence problems in some cases. In this paper, we present an implementation of the original Donnan Steric-partitioning Pore Model (DSPM) using COMSOL. Three different physical models were used and compared. The use of COMSOL benefits from the possibility of using stabilization techniques and the representation and analysis capabilities.
Effect of the membrane charge on magnesium sulphate rejection.
：Dependence of Potential and Ion Distribution on Electrokinetic Radius in Infinite and Finite-length Nano-channels J. Schiffbauer1, J. Fernandez2, W. Booth1, K. Kelly3, A. Timperman3, and B. Edwards1 1Physics Dept. West Virginia University, Morgantown, WV, USA 2Chemical Engineering Dept,West Virginia University, Morgantown, WV, USA 3Dept. of Chemistry, West Virginia University, Morgantown, WV, USA A site-binding/dissociation model is used to determine surface charge in numerical studies of the equilibrium potential and ion distributions inside infinite and finite-length nano-channels. This COMSOL model allows us to investigate the response of surface (zeta) potential to environmental parameters such as reservoir salt concentration, solution pH and wall separation. The resulting ion and potential distributions in the electric double-layer (EDL) are used to calculate near-equilibrium charge and fluid transport through a nano-channel, demonstrating the possibility of flow-reversal at low salt concentration.
An epifluorescence microscope image of the nano-microfluidic interfaces / nanocapillary membrane in the off-state showing concentration enhancement of anionic dye. The region to the right of the plug is believed to be ion-depleted.
：Uniformity Correction for Fluid Coating Head W. Vetterling ZINK Imaging, Bedford, MA, USA Slot coating is a widely used commercial process for applying one or more thin layers to a substrate such as paper, fabric, film or other material. In many cases, a highly uniform thickness is required, where a coating head that has been corrected for use with a Newtonian fluid may not produce a uniform coating when used with non-Newtonian fluids. With a multiphysics calculation involving the simultaneous solution of fluid dynamic and thermal diffusion equations within a fluid coating die, we have demonstrated the correction of a cross-web flow nonuniformity with a counterbalancing temperature nonuniformity.
This COMSOL plot shows the temperature profile of the coating fluid when the inlet fluid temperature is 10oC below the temperature of the coating head. As the fluid flows down the lateral arm, it is progressively warmed and its viscosity decreases.
：Plasma Edge Simulations by Finite Elements using COMSOL C. Hollenstein, and A. Howling Ecole Polytechnique Fédérale de Lausanne, Switzerland Finite elements using COMSOL Multiphysics have been used to simulate the edge plasma in a large area capacitively coupled RF reactor. In order to reduce numerical difficulties simplified reactor edge geometries have been used. First results show the importance of electrostatic double layers within this plasma. In addition the non-uniform behaviour of the plasma sheath around convex and concave corners turns out to be a basic feature of the edge plasma. The plasma physics and plasma-wall interaction are strongly influenced by these elementary structures. The simple model and simple geometry result in an important tool giving new insights and understanding into the physics of RF edge plasmas. The simulations help design reactor walls to optimize the RF plasma in industrial reactors.
The RF reactor geometries considered in this paper: Surface plot of the electron density and contour plot of the electric potential.
：Kinetics and Reactor Modeling of Methanol Synthesis from Synthesis Gas H. Bakhtiary, F. Hayer, H. Venvik, A. Holmen Norwegian University of Science and Technology Trondheim Methanol synthesis is a typical reaction in heterogeneous catalysis. In this work, we have studied a laboratory fixed-bed reactor packed with a Cu/Zn/Al2O3 catalyst in both adiabatic and isothermal tubular operational modes. A methanol synthesis kinetic model was implemented in COMSOL Reaction Engineering Lab. Both 1D and 2D pseudo-homogeneous dispersion models were applied to describe the mass and heat transfer in the reactor. Simulation of the reactor for the given operational conditions has been carried out to estimate reactor conversion and radial and axial temperature profiles. The effect of reactor shell temperature on the conversion has been studied and reported. Comparison of the results with similar work shows a good agreement.
The wall temperature strongly affects bed temperature distribution.
：FEM Analysis of Contaminant Transport in a Loamy Desert Soil B. Agasanapura, C. Nesbitt, and M. Misra Chemical and Metallurgical Engineering, University of Nevada, Reno, Nevada, USA In the present work, transport and adsorption of contaminants (lead, cesium) on loamy desert soil was modeled using the Finite Element Method (FEM). The Advective dispersion reaction mechanism was employed to describe the contaminant transport in soil medium. A partial differential equation (PDE) obtained from unsteady mass balance was developed using convective diffusion, solute adsorption, and dispersion terms. The adsorption isotherm equation was coupled with an Advective Dispersion Reaction (ADR) equation and the resulting unsteady nonlinear PDE was solved using COMSOL Multiphysics. Breakthrough profiles for adsorption that were obtained from modeling agree well with the experimental results.
3D representation of how water and contaminates flow through soil in Nevada test site. Ref: www.nv.doe.gov
：Simulation of C-MEMS Based Enzymatic Biofuel Cell Y. Parikh, V. Penmatsa, J. Yang, and C. Wang Department of Mechanical & Material Science Engineering, Florida International University, Miami, FL, USA An Enzymatic Biofuel Cell (EBFC) converts the chemical energy in biological fuels into electricity. In this work, we optimize the performance of the Carbon-Micro Electro Mechanical system in an EBFC by using COMSOL Multiphysics. With a simple model, we realized that most of the glucose reacts with enzymes at the top of the electrode posts, while the bottoms of the posts remain deficient of the substance. This is due to the slow diffusion of the glucose and high reaction rate of enzymes. In a more complex model of an EBFC, the potential distribution was modeled taking into account glucose and O2 diffusion around the electrode posts and the redox reaction of fuels based on enzyme kinetics.
This image created with COMSOL Multiphysics shows the surface plot of potential around the electrodes.
：Pseudo 3-D Simulation of a Falling Film Microreactor M. Al-Rawashdeh1,2, V. Hessel1,2, P. Löb1, and F. Schönfeld1 Institut für Mikrotechnik Mainz GmbH, Mainz, Germany Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, Netherlands
1 2
Gas-liquid falling film microreactors carry out fast exothermic and mass transfer limited reactions. Since the major rate limiting steps occur on the liquid side, it is important to account for a realistic liquid film profile within the reactor simulation. Based on realistic channel geometry and liquid menisci profiles, we describe the liquid film thicknesses, flow velocities, species transport and reactions. The reactor model was developed and validated experimentally.
Channel geometry analysis - Liquid film height.
：High-Temperature Sodium/Metal Chloride Storage Battery M. Vallance1, and R. White2 1 2
General Electric Global Research Center, Niskayuna, NY, USA Department of Chemical Engineering, University of South Carolina, Columbia, SC, USA
Sodium/metal chloride storage batteries, used in hybrid propulsion applications, provide high energy and power densities safely and reliably. To understand the dynamics of electrochemical cycling, a high-temperature sodium/ferrous chloride storage cell was modeled in two dimensions. The time-dependent solution shows that a reaction front, starting at the interface with the negative electrode, moves deeper into the positive electrode with increasing depth of discharge. Cell potential falls continuously as the discharge front moves deeper; Ohmic resistance in the porous electrode limits cell performance. Surface maps of areal transfer current density. This work, authored by Michael Vallance, GE Global Research, and Ralph White, University of South Carolina, won the "COMSOL Award for a Greener Tomorrow" at the COMSOL Conference 2008 Boston.
：Simulation of a Diesel Oxidation Catalyst Used in a NOx Storage and Reduction system for Heavy Duty Trucks C. Odenbrand, and E. Senar Serra Department of Chemical Engineering, Lund University, Lund, Sweden This work concerns the performance of an oxidation catalyst used in a NOx storage and reduction system. The oxidation of NO is the main objective of this study, where the presence of CO and propene has also been taken into account. Experimental data has been determined on a monolithic oxidation catalyst mounted after a heavy duty diesel engine in a rig. The conversion of hydrocarbons is predicted fairly well. The temperature increase determined experimentally cannot be simulated. This leads us to believe that there must be an extra highly exothermic reaction taking place. This could be the combustion of the volatile part of diesel soot. Simulated steady state values of the NO2 molar fraction in the channel and the catalyst layer.
：Numerical Solutions for the Lévêque Problem of Boundary Layer
Mass or Heat Flux
E. Holzbecher Weierstrass Institute for Applied Analysis and Stochastics (WIAS), Berlin, Germany The Lévêque problem is an idealized simple situation concerning the influence of the boundary on the distribution of temperature or mass in Hagen-Poiseuille flow. Here, the performance of numerical solutions is examined for a range of Péclet numbers, spanning 11 orders of magnitude. We examine the Sherwood, resp. Nusselt numbers and confirm the cubic square rule for high flow velocities. Moreover, we report on the effect of grid refinement and stabilization schemes.
Concentration distributions for different Peclet-numbers; from top to bottom: Pe=0.1, 1, 10, 100, 1000, 10000.
：Mathematical Investigation and CFD Simulation of Monolith Reactors: Catalytic Combustion of Methane M. Ghadrdan1, and H. Mehdizadeh2 Department of Chemical Engineering, Norwegian University of Science and Technology (NTNU), Trondheim, Norway 2 Department of Chemical Engineering, Tarbiat Modares University, Tehran, Iran 1
Interest in the production of hydrogen from hydrocarbons has grown significantly recently. In order to achieve high surface to volume ratio with reasonable pressure drop, monolithic reactors are used. The goal of this work is to develop a two-phase (gas & solid) transient catalytic combustor model using a simplified flow field inside a single channel to test the advantages of the COMSOL Multiphysics software. The flow field model includes axial convective transport with transverse energy and mass exchange via heat and mass transfer correlations. The solid is a thermally thin shell along which finite-rate heat conduction occurs in the axial direction. It is shown that the Nusselt number does not correlate with the Graetz number but rather depends on the variables such as gas velocity, inlet temperature and reactant concentration.
Concentration profile along the channel.
