^{}Department of Mechanical Engineering, Aerospace group Tarbiat Modares University, Tehran, Iran

Abstract

In recent years energy shortage and environmental impacts due to consuming fossil fuels have led to developing renewable energy sources systems. Since these sources are not reliable and are usually time dependent, an energy storing system like hydrogen production is required. In this regard, PEM electrolyzer can be efficiently used to decompose liquid water into hydrogen and oxygen. Because of dynamic nature of renewable sources, dynamic model of PEM electrolyzer is a necessity for investigating its performance. In this paper, a new one-dimensional dynamic model of PEM electrolyzer which at each time step solves electrochemical and two phase fluid flow equations is proposed. To solve a set of nonlinear partial differential equations of fluid flow, finite volume method with upwind scheme is used for discretization. The obtained algebraic set of equations is implicitly solved to ensure good stability at large time steps as well as low mesh nodes which provide the capability of system level simulation. Storing produced gas from electrolysis process continuously increases vessels pressure and leads to dynamic behavior of the electrolyzer. This phenomenon is investigated in this research using the proposed model. Results show that although the concentration of produced gas is raised by increasing vessel pressure, hydrogen concentration is essentially constant along the electrolyzer at cathode side. It is also observed that increasing vessel pressure results in high power consumption. However when pressure at anode side gets the moderate level, the water mass flow rate can be reduced, which causes a reduction in pump energy consumption.

1. Kim H., Park M. and Lee K. S., "One-dimensional dynamic modeling of a highpressure water electrolysis system for hydrogen production", Int J Hydrogen Energy, 2013, 38: 2596

2. Marangio F., Pagani M., Santarelli M. and Cali M., "Concept of a high pressure PEM electrolyser prototype", Int J Hydrogen Energy, 2011, 36: 7807

3. Gorgun H., "Dynamic modeling of a proton exchange membrane (PEM) electrolyzer", Int J Hydrogen Energy, 2006, 31: 29

4. Grigoriev, S.A., Porembskiy V.I., Korobtsev S.V., Fateev V.N., Auprêtre F. and Millet P., "High-pressure PEM water electrolysis and corresponding safety issues", Int J Hydrogen Energy, 2011, 36: 2721

5. Santarelli M., Medina P. and Cali M., "Fitting regression model and experimental validation for a high pressure PEM electrolyzer", Int J Hydrogen Energy, 2009, 34: 2519

6. Roy A., Watson S. and Infield D.,"Comparison of electrical energy efficiency of atmospheric and high-pressure electolysers", Int J Hydrogen Energy, 2006, 31: 1964

7. Onda K., Takahiro K., Kikuo H. and Kohei I., "Prediction of production power for high-pressure hydrogen by high-pressure water electrolysis", Journal of Power Sources, 2004, 132: 64

8. Todd D., Schwager M. and Mercida W., "Thermodynamics of high-temperature, high-pressure water electrolysis", Journal of Power Sources, 2014, 269: 424

9. Dale N.V., Mann M.D. and Salehfar H., "Semi-empirical model based on thermodynamic principles for determining 6 kW proton exchange membrane electrolyzer stack characterstics", Journal of Power Sources, 2008, 185: 1348

10. Marangio, F., Santarelli, M. and Cali, M., "Theoretical model and experimental analysis of a high pressure PEM water electrolyzer for hydrogen production", Int J Hydrogen Energy, 2009, 34: 1143

11. Awasthi, A., Scott K. and Basu S., "Dynamic modeling and simulation of a proton exchange membrane electrolyzer for hydrogen production", Int J Hydrogen Energy, 2011, 36: 14779

12. Lee B. Park K. and Man Kim H. "Dynamic Simulation of PEM Water Electrolysis and Comparison with Experiments", Int. J. Electrochem, 2013, 8: 235

13. Medina P. and Santarelli M., "Analysis of water transport in a high pressure PEM electrolyzer", International Journal of Hydrogen Energy, 2010, 35: 5173

14. Larminie J. and Dicks A., 2^{nd} ed., Fuel cell systems explained, John Wiley & Sons, 2003

15. Bird R. B., Stewart W. E. and Lightfoot E. N., 2^{nd} ed., Transport Phenomena, John Wiley & Sons, 2007

16. Bertola V., 1^{st} ed., Modelling and Experimentation in Two-Phase Flow, Spring-Verlag Wien GmbH, 2014

17. Versteeg H. K., and Malalasekera W., 2^{nd} ed., Introduction to Computational Fluid Dynamics: The Finite Volume Method, Pearson Education Limited, 2007

18. Rheinboldt W. C. 2^{end} ed., Methods for Solving Systems of Nonlinear Equations, SIAM, 1998

19. Abbaspour M., Chapman K. S. and Glasgow L., "Transient modeling of non-isothermal, dispersed two-phase flow in natural gas pipelines", Applied Mathematical Modelling, 2010, 34, 495