### Resumé

In this work, a state-of-the-art, full-scale, Proton Exchange Membrane (PEM) electrolysis cell model is presented. The developed three-dimensional (3D) model accounts for compressible, two-phase flow including species, heat and charge transport in the anode and membrane. By incorporating electrochemistry as well as detailed heat and two-phase flow transport phenomena, the model is capable of studying cells at full-scale and for high current densities with high accuracy. To enable the modeling of thin catalyst layers (CL) for high current density operation in a 3D framework, the CL is modeled as an interfacial boundary. The necessary electrochemical parameters are obtained by fitting polarization curves of a two-dimensional version of the devised model to experimental measurements from a small cell. It is found that the obtained parameters are in agreement with literature values and that the fitted model is able to capture the performance for temperatures from 323 to 353 K and for current densities up to 5 A cm
^{−2}. Furthermore, it is identified that for high current density operation, three types of overpotential losses are nearly equally dominant: the anode kinetics, the PEM ohmic resistance and the non-membrane ohmic resistance due to poor electrical contact between layers and current constrictions in the CL. The developed 3D model is applied to three different circular, interdigitated anode flow fields aimed a high pressure and high current density operation. When operating the cell at a cathode pressure of 100 bar, a current density of 5 A cm
^{−2} and stoichiometric constant of 350, it is found that the cell potential shows little dependence on the applied flow field. However, large in-plane variations can occur that may impact lifetime significantly. Particularly for the temperature field, an in-plane difference of up to 20.2 K relative to the intended cell temperature is found in the worst case. For all three cases, the occurrence of hot spots is linked to the maldistribution of two-phase flow and current density. Out of the studied cases, it was found that equal land width between the channels gives the best distribution of charge, mass and heat.

Originalsprog | Engelsk |
---|---|

Tidsskrift | Electrochimica Acta |

Vol/bind | 293 |

Sider (fra-til) | 476-495 |

Antal sider | 20 |

ISSN | 0013-4686 |

DOI | |

Status | Udgivet - 10 jan. 2019 |

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**Towards uniformly distributed heat, mass and charge : A flow field design study for high pressure and high current density operation of PEM electrolysis cells.** / Olesen, Anders Christian; Frensch, Steffen Henrik; Kær, Søren Knudsen.

Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › peer review

TY - JOUR

T1 - Towards uniformly distributed heat, mass and charge

T2 - A flow field design study for high pressure and high current density operation of PEM electrolysis cells

AU - Olesen, Anders Christian

AU - Frensch, Steffen Henrik

AU - Kær, Søren Knudsen

PY - 2019/1/10

Y1 - 2019/1/10

N2 - In this work, a state-of-the-art, full-scale, Proton Exchange Membrane (PEM) electrolysis cell model is presented. The developed three-dimensional (3D) model accounts for compressible, two-phase flow including species, heat and charge transport in the anode and membrane. By incorporating electrochemistry as well as detailed heat and two-phase flow transport phenomena, the model is capable of studying cells at full-scale and for high current densities with high accuracy. To enable the modeling of thin catalyst layers (CL) for high current density operation in a 3D framework, the CL is modeled as an interfacial boundary. The necessary electrochemical parameters are obtained by fitting polarization curves of a two-dimensional version of the devised model to experimental measurements from a small cell. It is found that the obtained parameters are in agreement with literature values and that the fitted model is able to capture the performance for temperatures from 323 to 353 K and for current densities up to 5 A cm −2. Furthermore, it is identified that for high current density operation, three types of overpotential losses are nearly equally dominant: the anode kinetics, the PEM ohmic resistance and the non-membrane ohmic resistance due to poor electrical contact between layers and current constrictions in the CL. The developed 3D model is applied to three different circular, interdigitated anode flow fields aimed a high pressure and high current density operation. When operating the cell at a cathode pressure of 100 bar, a current density of 5 A cm −2 and stoichiometric constant of 350, it is found that the cell potential shows little dependence on the applied flow field. However, large in-plane variations can occur that may impact lifetime significantly. Particularly for the temperature field, an in-plane difference of up to 20.2 K relative to the intended cell temperature is found in the worst case. For all three cases, the occurrence of hot spots is linked to the maldistribution of two-phase flow and current density. Out of the studied cases, it was found that equal land width between the channels gives the best distribution of charge, mass and heat.

AB - In this work, a state-of-the-art, full-scale, Proton Exchange Membrane (PEM) electrolysis cell model is presented. The developed three-dimensional (3D) model accounts for compressible, two-phase flow including species, heat and charge transport in the anode and membrane. By incorporating electrochemistry as well as detailed heat and two-phase flow transport phenomena, the model is capable of studying cells at full-scale and for high current densities with high accuracy. To enable the modeling of thin catalyst layers (CL) for high current density operation in a 3D framework, the CL is modeled as an interfacial boundary. The necessary electrochemical parameters are obtained by fitting polarization curves of a two-dimensional version of the devised model to experimental measurements from a small cell. It is found that the obtained parameters are in agreement with literature values and that the fitted model is able to capture the performance for temperatures from 323 to 353 K and for current densities up to 5 A cm −2. Furthermore, it is identified that for high current density operation, three types of overpotential losses are nearly equally dominant: the anode kinetics, the PEM ohmic resistance and the non-membrane ohmic resistance due to poor electrical contact between layers and current constrictions in the CL. The developed 3D model is applied to three different circular, interdigitated anode flow fields aimed a high pressure and high current density operation. When operating the cell at a cathode pressure of 100 bar, a current density of 5 A cm −2 and stoichiometric constant of 350, it is found that the cell potential shows little dependence on the applied flow field. However, large in-plane variations can occur that may impact lifetime significantly. Particularly for the temperature field, an in-plane difference of up to 20.2 K relative to the intended cell temperature is found in the worst case. For all three cases, the occurrence of hot spots is linked to the maldistribution of two-phase flow and current density. Out of the studied cases, it was found that equal land width between the channels gives the best distribution of charge, mass and heat.

KW - Electrolysis

KW - Full-scale

KW - Gas-liquid flow

KW - High current density

KW - Modeling

KW - PEM

UR - http://www.scopus.com/inward/record.url?scp=85054835249&partnerID=8YFLogxK

UR - http://vbn.aau.dk/en/publications/towards-uniformly-distributed-heat-mass-and-charge(d538f948-188e-40b7-931f-d6e30d7f8c5d).html

U2 - 10.1016/j.electacta.2018.10.008

DO - 10.1016/j.electacta.2018.10.008

M3 - Journal article

VL - 293

SP - 476

EP - 495

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

ER -