If a fuel cell is operated too dry or too wet, this is bad for the efficiency and service life of the cell. In dynamic operation, however, finding the right moisture balance is not always trivial. Real-time measurements could be used to identify the current status and use feedback loops to optimise it – and in consequence, potentially increase service life and efficiency.
The keyword here is optimised water management, relevant both in fuel cell design and in operation. It is one of the key building blocks for increasing the service life and efficiency of low-temperature polymer electrolyte membrane fuel cells (LT-PEMFCs). Yet, current methods for analysing the water balance are expensive and complex, cannot be used on standard cells or have difficulties with real-time monitoring of the water balance.
In the IGF project ‘US Fuel Cell - Monitoring the water balance in polymer electrolyte membrane fuel cells using surface ultrasound’, ZBT, together with its partners at TUD Dresden University of Technology and the Leibniz Institute for Solid State and Materials Research (IFW Dresden), is therefore developing a method with which the water distribution in LT-PEMFCs can be detected during operation with high temporal resolution. This method utilises ultrasonic surface waves, allows for an inexpensive instrumentation in the long term and can be implemented broadly for LT-PEMFCs with metallic bipolar plates.
The method is based on the measurable change in the propagation properties of surface waves in the fuel cell when droplets are located in the channels of the flow fields. This change allows for conclusions to be drawn about the position and quantity of water present. For this purpose, minimised ultrasound transducers are introduced at several positions in the flow field plate in order to derive the water distribution within the cell.
In the joint project, a functional model for measuring the water distribution within a fuel cell up to TRL 4 is to be developed. This requires the development and implementation of minimised ultrasonic transducers in the complex fuel cell system as well as validation and calibration using a reference in an X-ray tomograph. The practical relevance will be demonstrated by the application in an operating fuel cell.
Knowledge of the real-time water distribution in the fuel cell can be used to develop improved operating strategies, which in turn lead to increased efficiency and service life of LT-PEMFCs. In addition to this direct project objective, the project is expected to result in progress in areas ranging from sensor technology and bipolar plate optimisation to fuel cell design.
Project partners:
- Chair of Measurement and Sensor Systems Technology at TU Dresden
- Leibniz-Institute for Solid State and Materials Research (IFW Dresden)
Project duration and funding:
The project is funded by the German Federal Ministry for Economic Affairs and Climate Action via the IGF funding programme from 1 April 2024 to 30 September 2026 (funding code 01IF23280N).
