Meshing noise effect in design of experiments using computer experiments

Caire, Jean-Pierre; Chifflet, H.

doi:10.1002/env.539

Cited by 5 publications

(5 citation statements)

References 13 publications

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“…Caire et al [21] showed that the secondary distribution of potential is particularly sensitive to the grid length. This effect is due to the post-processing from the unknown factor potential V of current density J which mainly contributes to coupling in terms of mass and heat transfers (see Eq.…”

Section: Coupling Aspects and Meshing Boundsmentioning

confidence: 99%

Hydrogen filter press electrolyser modelled by coupling Fluent ® and Flux Expert ® codes

Jomard¹,

Feraud²,

Morandini³

et al. 2007

J Appl Electrochem

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Mass production of hydrogen is a major issue for the coming decades particularly to decrease greenhouse gas production. The development of fourth-generation high-temperature nuclear reactors has led to renewed interest for hydrogen production. In France, the CEA is investigating new processes using nuclear reactors, such as the Westinghouse hybrid cycle. A recent study was devoted to electrical modeling of the hydrogen electrolyzer, which is the key unit of this process. In this electrochemical reactor, hydrogen is reduced at the cathode and SO 2 is oxidized at the anode with the advantage of a very low voltage cell. This paper describes an improved model coupling the electrical and thermal phenomena with hydrodynamics in the electrolyzer, designed for a priori computational optimization of our future pilot cell. The hydrogen electrolyzer chosen here is a filter press design comprising a stack of identical cathode and anode compartments separated by a membrane. In a complex reactor of this type the main coupled physical phenomena involved are forced convection of the electrolyte flows, the plume of evolving hydrogen bubbles that modifies the local electrolyte conductivity, and all the irreversible processes that contribute to local overheating (Joule effect, overpotentials, etc.). The secondary current distribution was modeled with a commercial FEM code, Flux Expert 1 , which was customized with specific finite interfacial elements capable of describing the potential discontinuity associated with the electrochemical overpotential. Since the finite element method is not capable of properly describing the complex two-phase flows in the cathode compartment, the Fluent 1 CFD code was used for thermohydraulic computations. In this way each physical phenomenon was modeled using the best numerical method. The coupling implements an iterative process in which each code computes the physical data it has to transmit to the other one: the two-phase thermohydraulic problem is solved by Fluent 1 using the Flux-Expert 1 current density and heat sources; the secondary distribution and heat losses are solved by FluxExpert 1 using the Fluent 1 temperature field and flow velocities. A set of dedicated library routines was developed for process initiation, message passing, and synchronization of the two codes. The first results obtained with the two coupled commercial codes give realistic distributions for the electrical current density, gas fraction, and velocity in the electrolyzer. This approach allows us to optimize the design of a future experimental device. Notation CpHeat capacity (J kg -1 K -1 ) gGravitational acceleration (m s -2 ) J Current density (A m -2 ) Current density normal to the interface (A m -2 ) kThermal conductivity (W m -1 K -1 ) ñNormal vector NBN Number of integration points Q S Surface heat sources (W m -2 )Nanometric discontinuity thickness of potential (m) d S Dirac surface distribution e g Gas fraction qDensity (kg m -3 ) gOverpotential (V) rViscous stress tensor (Pa) rElectrical conductivity (X -1 m -...

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Section: Coupling Aspects and Meshing Boundsmentioning

confidence: 99%

Hydrogen filter press electrolyser modelled by coupling Fluent ® and Flux Expert ® codes

Jomard¹,

Feraud²,

Morandini³

et al. 2007

J Appl Electrochem

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“…Double precision is required since current density is post-processed from the potential distribution and careful meshing is necessary as shown by Caire and Chifflet [12].…”

Section: Boundary Conditionsmentioning

confidence: 99%

Hydrogen production by the Westinghouse cycle: modelling and optimization of the two-phase electrolysis cell

Charton¹,

Rivalier²,

Ode³

et al. 2009

WIT Transactions on Engineering Sciences

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Hydrogen is currently viewed as a promising energy carrier for transportation applications. In this context, mass production of hydrogen is a major issue for the coming decades. Among the viable production processes, the hybrid sulphur cycle, or Westinghouse cycle, is studied by the Nuclear Energy Division of the French CEA. In this work, the influence of H 2 bubbles on the current distribution within the electrolyser is studied. Turbulent two-phase flow simulations are performed with Ansys-Fluent CFD code in the 3D calculation domain using an Euler-Euler model. The electrokinetic problem is solved in the same domain by a finite element code, Flux-Expert, which is able to compute the secondary current distribution by means of specific interfacial elements. Parameters including the cell orientation (vertical or horizontal electrode), flow regime and bubble size are investigated, and the current model development status and needs are discussed.

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“…They appear in various fields of electrochemical engineering such as electrodeposition [1,4,5,7,[10][11][12][13][14][15][16], electro-machining [17], electropolishing [8], and corrosion processes [6]. Most popular commercial codes are now able to compute primary, secondary or tertiary current distributions for any geometry.…”

Section: Introductionmentioning

confidence: 99%

“…Since then, many authors tried to compute moving profiles by use of different numerical methods such as finite difference method (FDM) [6,10,12,14], boundary element method (BEM) [1,5,9], finite element method (FEM) [7,11,12], or specific methods [16]. All these authors used the same manual iterative process but Chauvy and Landolt [17] who developed a specific FORTRAN 77 code to compute the shape evolution of cavities produced by multistep electrochemical micromachining (the CREVICER code [18] developed for corrosion purposes does not have yet this capability).…”

Section: Introductionmentioning

confidence: 99%

“…The tests are here voluntarily restricted to electrochemical deposits corresponding to primary current density distributions. Calculations are simpler and such tests are more severe since the primary current distribution is known to give steep profiles and be very sensitive to the mesh quality [12]. Figure 1 shows the displacement of the metal-electrolyte boundary due to an electrochemical deposit carried out during a time step.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Dynamic simulation of a deposition process

Caire¹,

Javidi²

2007

WIT Transactions on Engineering Sciences, Vol 54

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A new solution for the computation of a current distribution with a moving boundary is presented. The numerical scheme is based on the capabilities of two commercial codes FEMLAB 2.3 and MATLAB 6.1. First a computation is carried out with FEMLAB which provides the electrical potential distribution at the initial time. The FEM problem and its initial solution are then saved as a MATLAB program. The MATLAB code containing the whole -draw, mesh, solve, plot -sequence is then modified to automate the iterative process. A movie is finally made from the successive solutions stored as JPEG pictures. A metal deposition process is presented as a simple test but difficult benchmark. This method is validated and can be easily extended to much more complex coupled electrochemical processes.

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Meshing noise effect in design of experiments using computer experiments

Cited by 5 publications

References 13 publications

Hydrogen filter press electrolyser modelled by coupling Fluent ® and Flux Expert ® codes

Hydrogen filter press electrolyser modelled by coupling Fluent ® and Flux Expert ® codes

Hydrogen production by the Westinghouse cycle: modelling and optimization of the two-phase electrolysis cell

Dynamic simulation of a deposition process

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