Icone15-10639 Modeling a Filter Press Electrolyzer for the Westinghouse Hybrid Cycle Using Two Coupled Codes

Jomard, Florent; Feraud, Jean-Pierre; Morandini, Jacques; Couvat, Y. Du Terrail; Caire, Jean-Pierre

doi:10.1299/jsmeicone.2007.15._icone1510_351

Cited by 2 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In France, the CNRS is involved in the IV Thorium -Uranium 233 molten salt reactor (TMSR) which presents many attractive features: simple design, operational safety (In the event of salt leak, the fluid escapes and freezes. In case of thermal runaway, the frozen salt valves melt down), little risk of proliferation, little risk of pollution, on line simplified reprocessing of fuel (gas and noble metal products are extracted by bubbling), good output, facility of control, ability of working at high temperatures (the boiling point of most molten salts being considered is higher than 1400°C), good compatibility with the mass production of hydrogen at high temperature (Jomard, 2006).…”

Section: Introductionmentioning

confidence: 99%

Icone15-10493 Pre Design of a Molten Salt Thorium Reactor Loop

Caire

Roure

2007

ICONE

Self Cite

View full text Add to dashboard Cite

This study is a contribution to the 2004 PCR-RSF program of the Centre National de la Recherche Scientifique (CNRS) devoted to research on high temperature thorium molten salt reactors.A major issue of high temperature molten salt reactors is the very large heat duty to be transferred from primary to secondary loop of the reactor with minimal thermal losses. A possible inner loop made of a series of conventional graphite filter plate exchangers, pipes and pumps was investigated. The loop was assumed to use two counter current flows of the same LiF, BeF 2 , ZrF 4 , UF 4 molten salt flowing through the reactor. The 3D model used the coupling of k-ε turbulent Navier-Stokes equations and thermal applications of the Heat Transfer module of COMSOL Multiphysics. For a reactor delivering 2700 MWth, the model required a set of 114 identical exchangers. Each one was optimized to limit the heat losses to 2882 W. The pipes made of a succession of graphite, ceramics, Hastelloy-N alloy and insulating Microtherm ® layers led to a thermal loss limited to 550 W per linear meter.In such conditions, the global thermal losses represent only 0.013 % of the reactor thermal power for elements covered with an insulator only 3 cm thick.

show abstract

Section: Introductionmentioning

confidence: 99%

Icone15-10493 Pre Design of a Molten Salt Thorium Reactor Loop

Caire

Roure

2007

ICONE

Self Cite

View full text Add to dashboard Cite

show abstract

“…This paper describes the work carried out to model and optimize a filter press electrolyser [6] for producing hydrogen via the Westinghouse hybrid cycle [7]. Considering the cost and complexity of fabricating a filter press electrolyser, numerical modelling proved to be a valuable tool for the preliminary design of a prototype unit.…”

mentioning

confidence: 99%

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

Jomard¹,

Feraud²,

Morandini³

et al. 2007

J Appl Electrochem

View full text Add to dashboard Cite

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 -...

show abstract

Icone15-10639 Modeling a Filter Press Electrolyzer for the Westinghouse Hybrid Cycle Using Two Coupled Codes

Cited by 2 publications

References 0 publications

Icone15-10493 Pre Design of a Molten Salt Thorium Reactor Loop

Icone15-10493 Pre Design of a Molten Salt Thorium Reactor Loop

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

Contact Info

Product

Resources

About