FLOWMEX – More efficient fuel cells through systematically improved water management

Researchers want to significantly improve water management in fuel cells. Using model-based and experimental methods, they are developing a simulation tool that realistically depicts the transport of liquid water in gas diffusion layers and flow field channels. This tool should enable systematically improved fuel cell designs.



Excerpt from an XTM image showing water distribution in a fuel cell in a channel of a bipolar plate and the adjacent gas diffusion layer

Optimisation

Electricity generation from green hydrogen is already highly efficient with low-temperature polymer electrolyte membrane (PEM) fuel cells. However, there is still considerable potential for further improvement, particularly through optimised liquid water management.

A key challenge is the accumulation of product water, which obstructs oxygen transport, lowers performance, and shortens the service life of fuel cells. Uneven water distribution within the porous gas diffusion layers and the connected flow channels is still one major challenge. Because of the structural complexity and the interplay of physical processes, currently available simulation methods are not accurate enough to enable optimization under industry-relevant conditions.

Enabling new flow field designs

The FLOWMEX project aims to fundamentally improve water management in fuel cells. The focus is on developing and validating a new, computationally efficient simulation tool that realistically maps the transport of liquid water in gas diffusion layers and flow field channels. With the help of these models, new flowfield designs are developed, constructively evaluated and validated in test fuel cells.

The simulation model is provided as an open source tool. This also gives small and medium-sized enterprises (SMEs) the opportunity to develop components more efficiently and without expensive high-performance computers or commercial software.

 

Combining methods

  • Experimental investigations: Optical flow measurements, laser-optical methods (µPIV, LDV) and electrochemical tests on specially manufactured test cells
  • Numerical methods: Coupling of pore network and discrete particle models, validation with high-resolution VOF simulations and flow measurement data
  • Design & transfer: Development and evaluation of new flow field structures, production of test fuel cells and provision of the simulation model via a user-friendly web interface

 

Strengthening innovative capacity

FLOWMEX provides practical design principles for bipolar plates and flow fields that can deliver performance improvements of 20 to 30 percent. Although developed for fuel cell technology, the simulation model is also applicable to other areas, including electrolysis, filtration, and medical technology.

The project therefore makes an important contribution to the market ramp-up of hydrogen technologies and strengthens the innovative capacity of SMEs in Germany.

Data

FLOWMEX – FLOW field structuring to improve water transport in fuel cells using model-based and EXperimental methods

Project duration: 2025 to 2027

Partner:

  • ZBT – The Hydrogen and Fuel Cell Center
  • Chair of Fluid Mechanics (LSM) at the University of Wuppertal

Media

Liquid water visualisation using XTM in the GDL and channels of an operating fuel cell, from: J. Eller, J. Roth, F. Marone, M. Stampanoni, und F. N. Büchi, „Operando Properties of Gas Diffusion Layers: Saturation and Liquid Permeability“, J. Electrochem. Soc., Bd. 164, Nr. 2, S. F115–F126, 2017, doi: 10.1149/2.0881702jes. Liquid water visualisation using XTM in the GDL and channels of an operating fuel cell, from: J. Eller, J. Roth, F. Marone, M. Stampanoni, und F. N. Büchi, „Operando Properties of Gas Diffusion Layers: Saturation and Liquid Permeability“, J. Electrochem. Soc., Bd. 164, Nr. 2, S. F115–F126, 2017, doi: 10.1149/2.0881702jes.
Solution approach for developing the planned simulation method: coupling of DPM and PNM via an interface model (blue elements = ZBT focus areas) and necessary validations/verifications (yellow arrows) via detailed VOF+IBM simulations and experiments (green elements = LSM focus areas) | IBM = Immersed Boundary Method Solution approach for developing the planned simulation method: coupling of DPM and PNM via an interface model (blue elements = ZBT focus areas) and necessary validations/verifications (yellow arrows) via detailed VOF+IBM simulations and experiments (green elements = LSM focus areas) | IBM = Immersed Boundary Method

Contact

Team Lead Modeling and Simulation

Lukas Feierabend
+49 203 7598-2353

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