Effect of inhomogeneous compression on pressure

InterPore2019 Valencia

ID del Resumen : 161

Effect of inhomogeneous compression on pressure drop and species transport in electrodes of redox flow batteries Contenido Assembly compression induces large deformations in fibrous electrodes of redox flow batteries (RFBs), leading to significant changes in its mass and electrical transport properties, which impact cell performance and lifetime. Moreover, the rib-channel pattern of the bipolar plate results in a highly inhomogeneous compressive load on the electrode, so that while large strains are produced in the region under the rib, the virtually uncompressed region under the channel partially blocks the flow field. This creates important spatial variations in the mass and charge transport rates through the electrode and increases the pressure drop in the cell. Therefore, a thorough understanding of the effects of assembly compression is essential for an appropriate description of the physicochemical processes and pumping losses that take place in RFBs. In this work, micro X-ray computed tomography images of inhomogeneously compressed carbon-felt electrodes (0.89 µm/voxel), acquired at the Zeiss Centre for Correlative Microscopy in the Electrochemical Innovation Lab, are examined. Seven compression ratios are considered, ranging from 0% to 90%. The pressure drop and mass transport of active species are modeled using direct numerical simulation of the mass, momentum and species conservation equations on the 3D segmented data sets. Specifically, the velocity field is first determined by simulating a laminar flow through the electrode. Then, the species convection-diffusion equation with a heterogeneous reaction term on the fiber surface is solved. A detailed analysis of the effect of Reynolds, Schmidt and Damköhler numbers on the Sherwood number and the utilization factor (defined as the ratio of the actual to the maximum reaction rate) is performed in randomly selected sub-domains extracted from the regions under the channel and the land, as well as the transition region between them. The results extracted from this analysis will provide key information about the behavior of carbon-felt electrodes in real-life applications, where the compression ratio and the flow-field width are important parameters to be optimized.

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Primary author(s) : RUBIO-HAMMO, José M. (Departamento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid, Leganés); MUÑOZ-LORENTE, Miguel (Departamento de Ingeniería Térmica y de Fluidos,

Universidad Carlos III de Madrid); Dr. SHEARING, Paul R. (Electrochemical Innovation Lab, University College London); Dr. JERVIS, Rhodri (Electrochemical Innovation Lab, University College London); Dr. GARCÍA-SALABERRI, Pablo Ángel (Departamento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid)

Presenter(s) :

MUÑOZ-LORENTE, Miguel (Departamento de Ingeniería Térmica y de Fluidos, Universidad Carlos III de Madrid)

Clasificación de temáticas : MS 19 - MS 19 Electrochemical processes in porous media Tipo de contribución : Poster Comentarios: The speaker could be changed depending on the necessities. Enviado por Dr. GARCÍA-SALABERRI, Pablo Ángel el Saturday 17 November 2018