Modeling a Proton Exchange Membrane Fuel Cell Stack Cell by Cell: Illustration of a Mechanism for the Propagation of Degradations - Archive ouverte HAL Access content directly
Journal Articles Journal of The Electrochemical Society Year : 2021

Modeling a Proton Exchange Membrane Fuel Cell Stack Cell by Cell: Illustration of a Mechanism for the Propagation of Degradations

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Abstract

This paper is devoted to the modeling of a PEMFC fuel cell stack. First, to justify the hypotheses, original experimental results are presented and show that the gas flow rates feeding a cell in its stack environment highly depend on the thermal management. Then, the generic model of a cell in its stack environment is presented. A two-phase flow model is implemented to calculate the gas flow rates as a function of the pressure drops and considering the amount of liquid water present in both compartments. In this way, the dispatching of the total active gases flow rate between the different cells can therefore be described. Finally, a stack of five cells is numerically assembled by describing the thermal coupling between the cells. Two application examples are conducted. A first one considers a cooling defect and a second one simulates the case where one cell is more degraded than the others. It is shown how these types of malfunction can cause a fuel starvation event. At the end, and for the first time as far as we know, a mechanism of propagation of degradations from cell to cell is proposed. List of symbols Symbol Description Unit Symbol Description Unit C d l Double-layer capacity of the cell F R m Protonic resistance of the membrane and electrodes Ω C v a p water vapor concentration mol m −3 R t h Thermal resistance K W −1 C O 2 Oxygen Concentration mol m −3 R d i f f Mass transfer reisstance s m −3 C s a t T Concentration of the saturated vapor at T mol m −3 S w Water saturation in the channels C p Specific heat capacity of plate J/K.kg T Temperature K D v a p ⁎ , G D L Effective water vapor diffusion coefficient through the GDL m 2 s −1 U Cell potential V D m H 2 O Water diffusion coefficient in the membrane m 2 s −1 V c h Volume of channels m3 D O 2 G D L Effective oxygen diffusion coefficient through the GDL m 2 s −1 Greek Letters e G D L Thickness of the GDL m α o x Anodic charge transfer coefficient E 0 Standard cell potential V α r e d Cathodic charge transfer coefficient E W Equivalent weight of the membrane kg mol −1 γ Roughness factor of the electrode F Faraday constant C mol −1 Δ P Pressure drop Pa I Current intensity A ξ Electro-osmosis coefficient I 0 Exchange current density A m −2 λ Water content of the membrane K M E A t h thermal capacity of the MEA J K −1 λ G D L Effective thermal conductivity of GDL W mK −1 K p t h thermal capacity of the anode/cathode plates J K −1 ρ Volumetric mass kg m −3 L Length of the active area m ϕ Cathode electrode potential V L v Water latent heat kJ mol −1 Upper & lower scripts Δ H H 2 lower heating value of Hydrogen kJ mol −1 in Inlet M H 2 O Molar mass of water kg mol −1 out Outlet N a i r Dry air molar flow rate mol s −1 c Cathode N H 2 Dry hydrogen molar flow rate mol s −1 a Anode N v a p Water vapor molar flow rate mol s −1 ch Channels N v a p e l → c h Water vapor flow rate from electrode to channels mol s −1 el Electrode P 0 Atmospheric pressure mol s −1 m Membrane P a Total pressure in the anode channels Pa cf Cooling fluid P c Total pressure in the cathode channels Pa n −1 Preceding electrode R Universal gas constant J mol.K −1 n + 1 Following electrode R e Electrical resistance of the cell Ω

Dates and versions

hal-03483327 , version 1 (16-12-2021)

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Sophie Didierjean, M. Bahrami, R. Bligny, J. Dillet, Jean-Philippe Martin, et al.. Modeling a Proton Exchange Membrane Fuel Cell Stack Cell by Cell: Illustration of a Mechanism for the Propagation of Degradations. Journal of The Electrochemical Society, 2021, 168 (9), pp.094507. ⟨10.1149/1945-7111/ac2686⟩. ⟨hal-03483327⟩
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