CFD Contribution on Fuel Cell Development
Antetomaso Christian, Irimescu Adrian and Merola Simona Silvia*
Published: November 30, 2022
Abstract
The need to move away from fossil energy sources has never been so strong. One of the technologies under the spotlight in recent years is certainly that of Fuel Cells (FC). Direct Methanol Fuel Cells (DMFC), Solid Oxide Fuel Cells (SOFC) or Molten Carbonate Fuel Cells (MCFC) represent different developing paths of this technology, but they all share a couple of benefits with respect to other energy conversion devices: they have no moving parts and a quite simple working principle. But how can we push forward the development of FCs?
Computational Fluid Dynamics (CFD) has been proven to be a powerful research aid in different fields of engineering. Similarly to other simulation tools (0D and 1D), 3D CFD opens up possibilities for parametric studies in a cost and time effective approach. Whether it’s evaluating the effects of air-fuel mixture formation in an engine [1], comparing the performance of several types of air foils [2] or calculating the drag coefficient of a car with variable spoiler angles [3], this is what everyday CFD has to deal with.
Different types of FCs require different considerations, so let’s focus on FCs for mobility: in this large family of by-products [4], Low Temperature Proton Exchange Membrane Fuel Cells (LT PEMFC) have been identified as the most suitable for vehicle implementation given their low operating temperature (80-100°C) and thus fast transient phase. This does not mean that this technology doesn’t show issues: current and voltage requirements force engineers to use a stack configuration of FCs, making it harder to keep the overall temperature field of the device under control, thus resulting in poor cell performance. Thermal management is a common problem for all FC types. A peculiar problem of LT PEMFC is flooding: the redox reaction taking place in the Membrane Electrode Assembly (MEA) generates water. A humid MEA is able to enhance transport phenomena [5], but too much water could flood the pathways of reactant gases [6].
And, once again, the “deeper” we go in the stack configuration, the harder it is to regulate water removal rates. CFD can help us understand key design factors and improve overall FC performance. It is possible but quite difficult to prepare an experimental setup and observe water accumulation inside a working PEMFC: you could use plexiglass Bipolar Plates (BP) instead of metal ones, but the wettability of the surface will be affected.
Researchers developed several models to investigate different aspects of the interaction between water and MEA.