ORALS

SESSION: PhysicalFriPM1-R10	Vayenas International Symposium on Physical Chemistry and its applications for sustainable development
Fri Oct, 25 2019 / Room: Aphrodite B (100/Gr. F)
Session Chairs: Katerina Aifantis; Eftychia Martino; Session Monitor: TBA

15:15: [PhysicalFriPM108]
Experimental Investigation and Mathematical Modeling of Triode PEM Fuel Cells
Eftychia Martino¹ ; Alexandros Katsaounis² ; Constantinos Vayenas³ ; ¹University of Patras, Dept. of Chemical Engineering, Patras, Achaia, Greece; ²Department of Chemical Engineering, University of Patras, Patras, Greece; ³University of Patras, Patras, Greece;
Paper Id: 58 [Abstract]

Triode operation of fuel cells is an alternative approach for enhancing fuel cells’ power output under severe poisoning conditions which lead to high overpotentials. This innovation was developed and applied firstly on SOFCs and later on PEMFCs [1-4]. In a triode fuel cell, in addition to the anode and the cathode, there is a third auxiliary electrode in contact with the solid electrolyte (e.g. polymer electrolyte membrane in the case of PEMFCs). This electrode forms, together with the cathode, a second (auxiliary) electric circuit operating in parallel with the conventional main circuit of the fuel cell. The auxiliary circuit runs in the electrolytic mode, pumping ions (i.e. protons in the case of a PEMFC) from the cathode to the auxiliary electrode. This way, imposition of a potential difference between the auxiliary electrode and the cathode permits the primary circuit of the fuel cell to operate under previously inaccessible, i.e larger than 1.23 V, anode - cathode potentials. The triode operation of humidified PEM fuel cells has been investigated both with pure H₂ and with CO poisoned H₂ feed over commercial Vulcan supported Pt(30%)-Ru(15%) anodes. It was found that triode operation, which involves the use of a third, auxiliary, electrode, leads to up to 400% power output increase with the same CO poisoned H₂ gas feed. At low current densities, the power increase is accompanied by an increase in overall thermodynamic efficiency. A mathematical model, based on Kirchhoff’s laws, has been developed which is in reasonably good agreement with the experimental results. In order to gain some additional insight into the mechanism of triode operation, the model has been also extended to describe the potential distribution inside the Nafion membrane via the numerical solution of the Nernst-Planck equation. Both models and experiments have shown the critical role of minimizing the auxiliary-anode or auxiliary-cathode resistance, and this has led to improved comb-shaped anode or cathode electrode geometries.

References:
[1] S.P. Balomenou, C.G. Vayenas, Triode Fuel Cells and Batteries, J. Electrochem. Soc. 151 (2004) A1874. doi:10.1149/1.1795511.
[2] S.P. Balomenou, F. Sapountzi, D. Presvytes, M. Tsampas, C.G. Vayenas, Triode fuel cells, Solid State Ionics. 177 (2006) 2023-2027. doi:10.1016/j.ssi.2006.02.046.
[3] F.M. Sapountzi, S.C. Divane, M.N. Tsampas, C.G. Vayenas, Enhanced performance of CO poisoned proton exchange membrane fuel cells via triode operation, Electrochim. Acta. 56 (2011) 6966-6975. doi:10.1016/j.electacta.2011.06.012.
[4] E. Martino, G. Koilias, M. Athanasiou, A. Katsaounis, Y. Dimakopoulos, J. Tsamopoulos, C.G. Vayenas, Experimental investigation and mathematical modeling of triode PEM fuel cells, Electrochim. Acta. 248 (2017) 518-533. doi:10.1016/j.electacta.2017.07.168.

SESSION: PhysicalSatAM-R10	Vayenas International Symposium on Physical Chemistry and its applications for sustainable development
Sat Oct, 26 2019 / Room: Aphrodite B (100/Gr. F)
Session Chairs: Michael Stoukides; Costas Galiotis; Session Monitor: TBA

12:10: [PhysicalSatAM03]
Proton Internal Pressure Distribution Suggests a Simple Proton Structure
Dimitrios Grigoriou¹ ; Eftychia Martino² ; Constantinos Vayenas¹ ; ¹University of Patras, Patras, Greece; ²University of Patras, Dept. of Chemical Engineering, Patras, Achaia, Greece;
Paper Id: 89 [Abstract]

Understanding the origin of quark confinement in hadrons remains one of the most challenging problems in modern physics. Recently, the pressure distribution inside the proton was measured via deeply virtual Compton scattering. Surprisingly, strong repulsive pressure up to 10³⁵ pascals, the highest so far measured in our universe, was obtained near the center of the proton up to 0.6 fm, combined with strong binding energy at larger distances. We show here that this profile can be derived semi-quantitatively without any adjustable parameters using the rotating lepton model of composite particles (RLM), i.e. a proton structure comprising a ring of three gravitationally attracting rotating ultrarelativistic quarks. The RLM synthesizes Newton's gravitational law, Einstein's special relativity, and de Broglie's wavelength expression, thereby conforming to quantum mechanics. This also yields a simple analytical formula for the proton radius and for the maximum measured pressure which are in excellent agreement with the experimental values.

References:
1. V.D. Burkert, L. Elouadrhiri & F.X. Girod, <i> Nature</i>,<b> 557</b>, 396 (2018).
2. C.G. Vayenas, S. Souentie Gravity, special relativity and the strong force: A Bohr-Einstein-de-Broglie model for the formation of hadrons. (Springer, New York, 2012).
3. C.G. Vayenas, S. Souentie, & A. Fokas, Physica A, <b>405</b>, 360 (2014).