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5th European Symposium on Computer Aided Process Engineering ESCAPE-5

1994 Computers and Chemical Engineering  
Specifically, we have tested the numerical performance of this optimization method in Gibbs energy minimization for flash calculations, calculation of homogeneous azeotropes and data fitting in thermodynamic  ...  Our results indicate that, in general, proposed method is reliable to solve these problems and shows a reasonable computational effort.  ...  So, this problem is a good choice to test numerical performance of DSAM method.  ... 
doi:10.1016/0098-1354(94)88024-7 fatcat:q2db45s6krdcllhed7nfzfi2lm

5th European symposium on computer aided process engineering escape-5

1995 Computers and Chemical Engineering  
Specifically, we have tested the numerical performance of this optimization method in Gibbs energy minimization for flash calculations, calculation of homogeneous azeotropes and data fitting in thermodynamic  ...  Our results indicate that, in general, proposed method is reliable to solve these problems and shows a reasonable computational effort.  ...  So, this problem is a good choice to test numerical performance of DSAM method.  ... 
doi:10.1016/0098-1354(95)80002-6 fatcat:3jw6l4ynkzhbbjmf2yk5skuldq

Computing multi-species chemical equilibrium with an algorithm based on the reaction extents

Juan Manuel Paz-García, Björn Johannesson, Lisbeth M. Ottosen, Alexandra B. Ribeiro, José Miguel Rodríguez-Maroto
2013 Computers and Chemical Engineering  
A mathematical model for the solution of a set of chemical equilibrium equations in a multi-species and multiphase chemical system is described.  ...  The residual function, representing the distance to the equilibrium, is defined from the chemical potential (or Gibbs energy) of the chemical system.  ...  This research was funded as part of the project "Fundamentals of Electrokinetics in In-homogeneous Matrices", with project number 274-08-0386. J.M.  ... 
doi:10.1016/j.compchemeng.2013.06.013 fatcat:sat3hq7duraazic6fugtb2gmjy


2002 Chemistry education  
Eur.: 2002, 3, 5-17] KEY WORDS: problem solving; chemical-equilibrium problems; misconceptions; errors in chemical-equilibrium problem solving; misconceptions in chemical-equilibrium problem solving  ...  Chemical-equilibrium problems are among the most important and at the same time most complex and difficult general-chemistry problems.  ...  Most of the misconceptions are related to conceptual aspects not entering in numerical chemicalequilibrium problems, such as the dynamic character of chemical equilibrium, the rates of the forward and  ... 
doi:10.1039/b0rp90030c fatcat:7ajci23bafh25jsd7h3bsdq6ka

Reactive transport of chemicals in unsaturated soils: numerical model development and verification

Majid Sedighi, Hywel R. Thomas, Philip J. Vardon
2016 Canadian geotechnical journal (Print)  
This paper presents the development of a numerical model for reactive transport of multicomponent chemicals in unsaturated soils.  ...  The model has been developed based on a coupled thermal, hydraulic, chemical and mechanical formulation and extended by the inclusion of geochemical processes under mixed equilibrium and kinetically controlled  ...  chemicals), provides an efficient solution for the problems considered.  ... 
doi:10.1139/cgj-2014-0436 fatcat:n4i6646iffc4tp53t3yarjulom

Global Gibbs Free Energy Minimization in Reactive Systems via Harmony Search

Adrian Bonilla-Petriciolet, Ma. del Rosario Moreno-Virgen, Juan Jose Soto-Bernal
2012 International journal of Chemical Reactor Engineering  
In these conditions, conventional numerical methods are not suitable for solving reactive phase equilibrium problems.  ...  Phase equilibrium calculations in systems subject to chemical reactions play a major role in the design of reactive separation schemes including chemical reaction engineering.  ...  INTRODUCTION The simultaneous calculation of physical and chemical equilibrium is a fundamental numerical procedure in process system engineering including chemical reactor engineering (Wakeham and Stateva  ... 
doi:10.1515/1542-6580.2894 fatcat:ebkkl5lqqja27nl7bjdpxnwofi

Minimal curvature trajectories: Riemannian geometry concepts for slow manifold computation in chemical kinetics

Dirk Lebiedz, Volkmar Reinhardt, Jochen Siehr
2010 Journal of Computational Physics  
We present various geometrically motivated criteria and the results of their application to three test case reaction mechanisms serving as examples.  ...  We demonstrate that accurate numerical approximations of slow invariant manifolds can be obtained.  ...  We especially thank Andreas Potschka (IWR, Heidelberg) for continuous support concerning MUSCOD-II and many helpful hints related to derivative computation and problem formulation and Dr.  ... 
doi:10.1016/ fatcat:ojvdqrgzonfvfon7mez5pdxyze

Inviscid flux-splitting algorithms for real gases with non-equilibrium chemistry

Jian-Shun Shuen, Meng-Sing Liou, Bram Van Leer
1990 Journal of Computational Physics  
Several flux-splitting methods for the inviscid terms of the compressible-flow equations are derived for gases that are not in chemical equilibrium.  ...  Formulas are presented for the extension to chemical nonequilibrium of the Steger-Warming and Van Leer flux-vector splittings, and the Roe flux-difference splitting.  ...  NUMERICAL TEST Numerical tests have been conducted to validate the accuracy of the present formulation.  ... 
doi:10.1016/0021-9991(90)90172-w fatcat:aklzcur5afhebdb7np7sushdge

Application of a subdivision algorithm for solving nonlinear algebraic systems

Fernanda De Castilhos Corazza, José Vladimir de Oliveira, Marcos Lúcio Corazza
2008 Acta Scientiarum: Technology  
For this purpose, a web-based library available in the literature was used as the main source to select a wide class of one-and multidimensional problems, comprising phase and chemical equilibrium, conversion  ...  A subdivision algorithm is presented and applied to solving commonly found chemical engineering problems described by nonlinear algebraic systems.  ...  P2 Problem: chemical equilibrium I P2 Problem: chemical equilibrium I P2 Problem: chemical equilibrium I P2 Problem: chemical equilibrium I Problem P2 refers to chemical equilibrium, with an implicit equation  ... 
doi:10.4025/actascitechnol.v30i1.3198 fatcat:dnddottj4ff2layav6ounsb23u

Analysis and prediction of input multiplicity for the reactive flash separation using reaction-invariant composition variables

José Enrique Jaime-Leal, Adrián Bonilla-Petriciolet, Juan Gabriel Segovia-Hernández, Salvador Hernández, Héctor Hernández-Escoto
2012 Chemical engineering research & design  
In summary, our strategy can be applied with any reactive system and thermodynamic model, assuming that all reactions are reversible and in thermodynamic equilibrium and the operating conditions are away  ...  For these reactive systems, we report the existence of multiple states for different operating conditions.  ...  Note that the flash separation problem is one of the most important chemical engineering problems and is recurrent in the modeling and design of separation systems based on vapor-liquid phase equilibrium  ... 
doi:10.1016/j.cherd.2012.02.017 fatcat:2cedqbep6rgyblsmbd65frlgf4

Constrained and unconstrained Gibbs free energy minimization in reactive systems using genetic algorithm and differential evolution with tabu list

Adrián Bonilla-Petriciolet, Gade Pandu Rangaiah, Juan Gabriel Segovia-Hernández
2011 Fluid Phase Equilibria  
However, there are no previous studies on the performance of both these strategies to solve the Gibbs free energy minimization problem for systems subject to chemical equilibrium.  ...  Specifically, the numerical performance of these stochastic methods have been tested using both conventional and transformed composition variables as the decision vector for free energy minimization in  ...  The test problems include systems with vapor-liquid (VL) and liquid-liquid (LL) equilibrium.  ... 
doi:10.1016/j.fluid.2010.10.024 fatcat:d5zyul7p7zftvh6bdtpdqjahh4

Page 8194 of Mathematical Reviews Vol. , Issue 2000k [page]

2000 Mathematical Reviews  
Numeri- cal simulations of the full system are obtained and these show that, when travelling waves exist, these are formed as the long time behavior of the system.  ...  Results from this phys- ical model are compared with experiments and other results in the literature for an arcjet and non-equilibrium nozzle test case.  ... 

Ultra-Fast Reactive Transport Simulations When Chemical Reactions Meet Machine Learning: Chemical Equilibrium [article]

Allan M. M. Leal, Dmitrii A. Kulik, Martin O. Saar
2017 arXiv   pre-print
Thus, rather than proposing a fast-converging numerical method for solving chemical equilibrium equations, we present a machine learning method that enables new equilibrium states to be quickly and accurately  ...  We demonstrate the use of this smart chemical equilibrium method in a reactive transport modeling example and show that, even at early simulation times, the majority of all equilibrium calculations are  ...  Acceptance Testing Once a predicted chemical equilibrium state is calculated, one needs to test if it can be accepted.  ... 
arXiv:1708.04825v1 fatcat:e77lktpqwrbhfg6oi5376sicca

A comparative study of particle swarm optimization and its variants for phase stability and equilibrium calculations in multicomponent reactive and non-reactive systems

Adrián Bonilla-Petriciolet, Juan Gabriel Segovia-Hernández
2010 Fluid Phase Equilibria  
This study introduces the application of particle swarm optimization and several of its variants for solving phase stability and equilibrium problems in multicomponent systems with or without chemical  ...  The reliability and efficiency of a number of particle swarm optimization algorithms are tested and compared using multicomponent systems with vapor-liquid and liquid-liquid equilibrium.  ...  Our collection of test problems includes systems with vapor-liquid and liquid-liquid equilibrium.  ... 
doi:10.1016/j.fluid.2009.11.008 fatcat:e3x3unedufav7cjy2wgilyo4fu

A Variational Principle for Computing Slow Invariant Manifolds in Dissipative Dynamical Systems

Dirk Lebiedz, Jochen Siehr, Jonas Unger
2011 SIAM Journal on Scientific Computing  
Numerical results for the linear and nonlinear model problems as well as a more realistic higher-dimensional chemical reaction mechanism are presented.  ...  For a two-dimensional linear system and a common nonlinear test problem we show analytically that the variational approach asymptotically identifies the exact slow invariant manifold in the limit of both  ...  We consider autonomous ODE systems of the forṁ x = f (x) modeling chemical reaction kinetics that have a stable fixed point corresponding to chemical equilibrium.  ... 
doi:10.1137/100790318 fatcat:avxs76z5ongvre735f4byltiuu
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