Hydrogen production using the sulfur–iodine cycle coupled to a VHTR: An overview

Vitart, X.; Duigou, Alain Le; Carles, Philippe

doi:10.1016/j.enconman.2006.02.010

Cited by 89 publications

(38 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The gas is known to be released in this electrolyte at the cathode in bubbles 100 lm in diameter [2], is transported by the bath and exits at the top of the electrolyser. Figure 10 illustrates the hydrogen evolution along the interface between cathode and the sulphuric acid solution (catholyte); due to the combined fluid transport and bubble release at cathode, the gas volume fraction increases along the cathode wall.…”

Section: Results Of Two-phase Flow Calculationsmentioning

confidence: 99%

“…One of the main objectives is to take advantage of the very high-temperature heat source of 1100 K obtained at a reasonable cost by future nuclear reactors such as the Very High Temperature Reactor [1,2]. Large-scale hydrogen production is also being considered using hybrid cycles such as the Westinghouse Sulphur Cycle, which is based on sulphur dioxide oxidation and an electrochemical reduction of protons to form hydrogen [3,4].…”

mentioning

confidence: 99%

See 1 more Smart Citation

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

Section: Results Of Two-phase Flow Calculationsmentioning

confidence: 99%

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

show abstract

“…The S-I cycle has been considered the one of the most promising routes for hydrogen production from water splitting on a large scale [3,4]. Therefore, tremendous research has been done with this cycle, including experiments, process modelling, efficiency estimation, energy coupling, and chemical modification, etc.…”

Section: Brief Review Of the S-i Cyclementioning

confidence: 99%

“…Therefore, tremendous research has been done with this cycle, including experiments, process modelling, efficiency estimation, energy coupling, and chemical modification, etc. The S-I cycle was originally investigated by General Atomics Co. (GA) in the 1970s and the involved reactions with phase specification and reaction temperatures were presented in [3,4] as follows:…”

Section: Brief Review Of the S-i Cyclementioning

confidence: 99%

Hydrogen production from a chemical cycle of H2S splitting

Wang

2007

International Journal of Hydrogen Energy

View full text Add to dashboard Cite

“…Both cycles include the same high-temperature step described by the net chemical reaction: Sulfuric acid is evaporated and decomposed at approximately 610 K and the resulting SO 3 is reduced to SO 2 at 1500 K. The temperature of the SO 3 reduction step can be reduced when using catalysts such as Pt, Fe 2 O 3 , or mixtures of Pt and TiO 2 [23,24]. In the hybrid sulfur-based cycle [25,26], the subsequent step is an electrochemical reaction of water and SO 2 [27,28,29,30], the Bunsen reaction, described by eq. (3) and taking place at 400 K, follows the high temperature step, resulting in two immiscible aqueous solutions consisting of aqueous sulfuric acid and HI.…”

Section: Introductionmentioning

confidence: 99%

Multi-Scale Modelling of a Solar Reactor for the High-Temperature Step of a Sulphur-Iodine-Based Water Splitting Cycle

Haussener¹,

Thomey²,

Roeb³

et al. 2012

Volume 1: Heat Transfer in Energy Systems; Theory and Fundamental Research; Aerospace Heat Transfer; Gas Turbine Heat Transfer;

View full text Add to dashboard Cite

The 3-step sulphur-iodine-based thermochemical cycle for splitting water is considered. The high-temperature step consists of the evaporation, decomposition, and reduction of H 2 SO 4 to SO 2 using concentrated solar process heat. This step is followed by the Bunsen reaction and HI decomposition. The solar reactor concepts proposed are based on a shell-and-tube heat exchanger filled with catalytic packed beds and on a porous ceramic foam to directly absorb solar radiation and act as reaction site. The design, modeling, and optimization of the solar reactor using complex porous structures relies on the accurate determination of their effective heat and mass transport properties. Accordingly, a multi-scale approach is applied. Ceramic foam samples are scanned using highresolution X-ray tomography to obtain their exact 3D geometrical configuration, which in turn is used in direct porelevel simulations for the determination of the morphological and effective heat/mass transport properties. These are incorporated in a volume-averaged (continuum) model of the solar reactor. Model validation is accomplished by comparing numerically simulated and experimentally measured temperatures in a 1 kW reactor prototype tested in a solar furnace. The model is further applied to analyze the influence of foam properties, reactor geometry, and operational conditions on the reactor performance.

show abstract

Hydrogen production using the sulfur–iodine cycle coupled to a VHTR: An overview

Cited by 89 publications

References 4 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 from a chemical cycle of H2S splitting

Multi-Scale Modelling of a Solar Reactor for the High-Temperature Step of a Sulphur-Iodine-Based Water Splitting Cycle

Contact Info

Product

Resources

About