DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 1/19 Jean-Pierre Feraud, Florent Jomard, Denis Ode, Jean Duhamet Commissariat à l’Énergie Atomique DEN/DTEC/SGCS/LGCI Site de Marcoule BP Bagnols sur Cèze, France Yves du Terrail Couvat Laboratoire EPM, Madylam 1340 Rue de la Piscine Domaine Universitaire Saint Martin d’Hères, France Jean-Pierre Caire LEPMI, ENSEEG 1130 Rue de la Piscine Saint Martin d’Hères, France Modeling a filter press electrolyzer by using two coupled codes within nuclear Gen. IV hydrogen production. Jacques Morandini Astek Rhône-Alpes 1 place du Verseau Echirolles, France

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 2/19 I.Introduction II.The Westinghouse sulfur cycle III.Modeling objective IV.Coupling of physical phenomena with Fluent ® / Flux Expert ® codes V.Electrolyzer modeling, boundary conditions VI.Software coupling results VII.Conclusion – Future prospects

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 3/19 Extensive use of energy = hydrogen mass production High-temperature cycles for hydrogen production - 100% thermochemical: Bunsen Cycle… - Hybrid cycle: Westinghouse sulfur cycle, Deacon cycle… - 100% electrochemical cycle: high-temperature electrolysis of water I. Introduction High-temperature hydrogen production technologies could be provided by using: - Gen. IV nuclear power plants - Thermal solar facilities…

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 4/19 H 2, product ½ O 2 by-product II. The Westinghouse sulfur cycle Hybrid Sulfur Process block H 2 O feed Westinghouse sulfur cycle

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 5/19 H 2, product ½ O 2 by-product II. The Westinghouse sulfur cycle Hybrid Sulfur Process block H 2 O feed Thermal energy Filter press Electrolyzer (50 – 100°C) Concentration Evaporation Decomposition Absorption 300°C Concentration 300°C Thermal decomposition 850°C Evaporation 600°C Thermal energy H 2 O + SO 2 + ½ O 2  H 2 SO 4 Electrical energy Compression H 2 SO 4 side SO 2 side H 2 SO 4 SO 2 Cooling SO 2 H 2 O SO 2 H 2 O SO 2 H 2 O Absorption 25°C

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 6/19 Within the framework of the Westinghouse cycle studies The aim of our works consists of modeling a filter press electrolyzer for hydrogen production. III. Modeling objective Our studies have to take into account numerous physical interactions: - electrokinetics (overpotential), - thermal behavior (Joule effect), - fluid dynamics (forced convection), - multiphase flow (electrolyte + bubble plume). We expect that the virtual filter press design will work as a real one

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 7/19 IV. Coupling of physical phenomena with realizable Fluent® / Flux Expert® codes Physical phenomena: - Thermohydraulics solved with Fluent® Navier-Stokes continuity equations Heat transfer equation - CFD, Fluent model selected - so-called “realizable” k-ε turbulence model - two-phase flow description: Euler-Euler - separate phase: disperse phases Two-phase fluid dynamics

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 8/19 IV. Coupling of physical phenomena with Fluent® / Flux Expert® codes Physical phenomena : - Electrokinetics solved with Flux-Expert® Charge balance, Laplace equation Ohm’s law, primary current distribution (a) Secondary current distribution, Butler-Volmer Law (b) Electrode Electrolyte  (j) Potential (V) Cell width (a) Interface gap  (1) (2) (b) (a)

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 9/19 IV. Coupling of physical phenomena with Fluent® / Flux Expert® codes Software coupling: Fluent ® –Flux Expert ® coupling flowchart = message-passing function  Physical phenomena can be solved by using different meshes (structured or unstructured)  Communication between the two codes: simple and robust message-passing library  Algorithms developed are mainly location and interpolation algorithms

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 10/19 V. Electrolyzer modeling, boundary conditions : The FM01-LC laboratory scale electrolyzer:  0.16m 0.04m 0.013m H + +H 2 SO 4 H 2 SO 4 +  SO 2 H 2 SO 4 + SO 2 H 2 SO 4 H2H2 + -     z x y Electrolyzer operating principle  cathode  hydrogen release area  catholyte  membrane  anolyte  anode

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 11/19 V. Electrolyzer modeling, boundary conditions CATHOLYTE CATHODE membrane ANOLYTE ANODE Overpotential Area 0 V Y (mm) Overpotential area Z (mm) 2000 A.m -2 CATHOLYTE CATHODE membrane ANOLYTE ANODE Flux-Expert Hydrogen bubble velocity: 0.01 m·s -1 Bubble emission angle: 45° Uniform electrolyte velocity profile , ,k,c p : temperature-dependent No heat exchange with outside Hydrogen area 160 mm V = 0.07 m·s -1 T = 323 K CATHOLYTE CATHODE membrane ANOLYTE ANODE mm Fluent Boundary conditions to produce 5 NL·h -1 of hydrogen

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 12/ VI. Numerical results  Residual continuity  u residual sulphuric acid  u residual hydrogen  v residual sulphuric acid  v residual hydrogen  w residual sulphuric acid  w residual hydrogen  T 1 residual sulphuric acid  T 2 residual hydrogen  K residual sulphuric acid   residual sulphuric acid  (1–K) residual hydrogen FLUENT iterations Code Coupling Behavior Interaction between the two codes is demonstrated by the convergence of the computational residuals with successive iterations FLUX-EXPERT iterations

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 13/19 T =323 K υ = m.s -1 T =323 K υ = m.s m 0 m VI. Numerical results Thermal problem: Graded color scale Temp. (K)

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 14/19 3 mm VI. Numerical results Catholyte Cathode H 2 (vol.%) Cathode Anode membrane Hydrogen plume area approx. 1 mm Two-phase problem resolution:  Maximum concentration 0.2 mm from cathode  Hydrogen volume fraction < 72%

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 15/19 VI. Numerical results H 2 (vol.%) Cathode Anode Graded color scale height = 0.15m height = 0.08m height = 0.01m Two-phase problem resolution:

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 16/19 Anolyte VI. Numerical results Fluid dynamic calculation: Anolyte flow appearance: Flat (uniform velocity) + wall effect on membrane and anode sides  Characteristic of turbulent flow Catholyte flow appearance: Wall effect on membrane side, Increasing velocity on cathode side (×4)  Characteristic of air lift effect Catholyte Flow rate (m·s -1 ) Membrane

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 17/19 Anodic overpotential = 70% of cell potential Cell potential: 0.73V Goal: improve cell designing to obreach 0.6 V of total potential VI. Numerical results Electrokinetics calculation: V) Potential (V)

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 18/19 Modeling with Flux-Expert / Fluent Codes  Performed with message-passing library  Only 24 h of computing on Pentium IV (Flux Expert) + Core 2 Duo (Fluent) PCs CFD results  Electrolyte temperature rise: 4°C  Catholyte motion (×4), hydrogen bubbling effect Electrokinetics calculation  Electrochemical irreversible process taken into account with Flux Expert ®  Total cell voltage obtained: 0.73 V (in accordance with published results) VI. Conclusion – Future prospects

DEN/VRH/DTEC/SGCS/LGCIDenis ODEGLOBAL 2007 – Boise USA September 9-13 Modeling a filter press electrolyzer By using two coupled codes within nuclear Gen. IV hydrogen production 19/19 VI. Conclusion – Future prospects Calculation / Experiments  Experiments required to complete the lack of anodic overpotential law  Check the validity of two-phase flow behavior  Model a stack of cells before scaling up  Optimize the future electrochemical process by designing numerical experiments