1. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 1/21 Florent Jomard Commissariat à l’Énergie Atomique DEN/DTEC/STCF/LGCI Site de Marcoule BP 17171 30207 Bagnols sur Cèze, France Jean-Pierre Feraud Commissariat à l’Énergie Atomique DEN/DTEC/STCF/LGCI Site de Marcoule BP 17171 30207 Bagnols sur Cèze, France Jacques Morandini Astek Rhone-Alpes 1 place du Verseau 38130 Echirolles, France Yves Du Terrail Couvat Laboratoire EPM, Madylam 1340 Rue de la Piscine Domaine Universitaire 38400 Saint Martin d’Hères, France Jean-Pierre Caire LEPMI, ENSEEG 1130 Rue de la Piscine 38402 Saint Martin d’Hères, France MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES

2. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 2/21 I.Introduction II.The Westinghouse sulfur cycle III.Modeling aim IV.Coupling of physical phenomena with Fluent ® / Flux Expert ® codes V.Electrolyzer modeling, boundary conditions VI.Software coupling results VII.Conclusion, future prospect

3. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 3/21 Global warming context requires decreasing world's greenhouse gas emission I. Introduction hydrogen alternative solution to replace primary energy Exemple : Hydrogen + fuel cells can replace internal combustion engines CEA / PSA Fuel cells : GENEPAC ( GENérateur Electrique de Pile A Combustible) PSA hydrogen concept car ( 207 ePure)

4. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 4/21 wide uses of energy = hydrogen mass production High temperature cycles for hydrogen production - 100% thermochemical : Bunsen Cycle… - hybride 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…

5. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 5/21 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 Évaporation Décomposition 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 part SO 2 part 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 Westinghouse sulfur cycle

6. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 6/21 Process working conditions - -T°C : 50 - 100°C - - [H 2 SO 4 ] : 20 - 60 % weight - - PSO 2 1 bar - Current density 200 mA/cm² H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ e-e- II. The Westinghouse sulfur cycle membrane Two compartment membrane electolysis cell : Anode + + Cathode - - SO 2 2 H H 2 2 4 4 H H + + H H 2 2 Anolyte : H 2 O-SO 2 - H 2 SO 4 Catholyte: H 2 O – H 2 SO 4 SO 2 + 2H 2 O  H 2 SO 4 + 2H + + 2e - 2H + + 2e -  H 2

7. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 7/21 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 aim Our studies have to take into account numerous physical interactions : - electrokinetic (overpotential), - thermal behaviour (Joule effect), - fluid dynamics (forced convection), - multiphasic flow (electrolyte + bubble plume). We expect that the virtual filter press design will work as a real one

8. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 8/21 IV. Coupling of physical phenomena with Fluent® / Flux Expert® codes Physical phenomena : - Thermohydraulics (Fluent, finite volume method) Navier-Stokes continuity equations Heat transfert equation - CFD, Fluent model selected - k-ε turbulence model so-called « realizable » - diphasic flow description : Euler-Euler - separate phase : disperse phases momentum Diphasic fluid dynamic (1) (2)

9. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 9/21 IV. Coupling of physical phenomena with Fluent® / Flux Expert® codes Physical phenomena (continuation) : - Electrokinetics (Flux-Expert, finite element method) Charge Balance, Laplace equation : Ohm's Law, primary current distribution (a): Secondary current distribution, Butler-Volmer's Law (b) : Electrode Electrolyte  (j) Potential (V) Cell width (a) Interface gap  (1) (2) (b) (a)

10. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 10/21 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

11. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 11/21 FLUENT ® Solve the two phase Thermohydraulic problem Calculation of Temp. (K) in all the domain u (flow velocity) α g ( hydrogen concentration) FLUX EXPERT ® Solve the Electrokinetic problem Calculation of U : Potential (V) J : current densities (A.m -2 ) Qs/Qv : Thermal Joule effect ( W.m -3 ) Thermal and current densities inputs hydrogen concentration Temperature IV. Coupling of physical phenomena with Fluent ® / Flux Expert ® codes

12. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 12/21 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 With :  cathode,  hydrogen release area,  catholyte,  membrane,  anolyte,.  anode.

13. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 13/21 V. Electrolyzer modeling, boundary conditions CATHOLYTE CATHODE membran ANOLYTE ANODE Overpotential Area 0 V Y (mm) Overpotential Area Z (mm) 2000 A.m -2 CATHOLYTE CATHODE membrane ANOLYTE ANODE Flux-Expert Hydrogen bubbles velocity : 0.01m.s -1 bubble emission angle : 45° Electrolyte uniform velocity profile , ,k,c p : temperature dependent No thermal exchange with outside Hydrogen area 160 mm V= 0.07m.s -1 T=323K CATHOLYTE CATHODE membrane ANOLYTE ANODE 0 1.5 6.5 6.6 11.2 13 mm Fluent Boundary conditions to produce 5 Nl.h -1 of hydrogen

14. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 14/21 123 VI. Numerical results  Residuals 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

15. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 15/21 T =323 K υ = 0.069 m.s -1 T =323 K υ = 0.069 m.s - 1 0.16 m 0 m VI. Numerical results Thermal problem : Graded colors scale Temp. (K)

16. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 16/21 3 mm VI. Numerical results Catholyte Cathode % H 2 (vol.) Cathode Anode membrane Hydrogen plume area approx. 1 mm Diphasic problem resolution :  Hydrogen volume fraction < 72%  Maximum concentation at 0.2 mm from cathode

17. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 17/21 VI. Numerical results % H 2 (vol.) Cathode Anode Graded colors scale height = 0.15m height = 0.08m height = 0.01m Diphasic problem resolution :

18. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 18/21 Anolyte VI. Numerical results Fluid dynamic calculation : Anolyte flow appearance: Flat (uniform velocity) + wall effect on membrane and anode sides  Caracteristic of turbulent flow Catholyte flow appearance : Wall effect on membrane side, High velocity increasing on cathode side (X4)  Characteristic of air lift effect Catholyte Flow m.s -1 membrane

19. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 19/21 Anodic overpotential = 70 % tension of cell Tension of cell : 0.73V Goal : Design a cell to obtain 0.6 V of total tension VI. Numerical results Electrokinetics calculation : V) Potential (V)

20. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 20/21 Modeling with Flux-Expert / Fluent Codes  Performed with message-passing library  Only 24h of calculation on Pentium IV(F. Expert) + Core 2 Duo (Fluent) PC CFD results  Electrolyte rising temperature : 4°C  Catholyte motion (x4), hydrogen bubbly effect Electrokinetics calculation  Electrochemical irreversible process taken into account with Flux Expert®  Total cell tension obtained : 0.73V (in accordance with literature results) VI. Conclusion, future prospect

21. DEN/VRH/DTEC/STCF/LGCI JP FERAUD ICONE15, Nagoya 2007 April 22-26 MODELING A FILTER PRESS ELECTROLYZER FOR THE WESTINGHOUSE HYBRID CYCLE USING TWO COUPLED CODES ICONE15 -10639 21/21 VI. Conclusion, future prospect Calculation / Experiments  Experiments required to complete the lack of anodic overpotential law  Check Validity of diphasic flow behavior  development of specific physical operators  modelling a stack of cells before scaling-up  Optimization of the future electrochemical process with a design of numerical experiments