Objectives

The general objectives of the OPUS-H2: « Optimization of Performance and dUrability of hydrogen Systems using an advanced digital twin », project are to significantly contribute to the development of numerical models for PEM fuel cells in order to improve their performance and durability, as well as to build experimental expertise in collaboration with a well-established European partner in the field, with the aim of transferring these skills to Réunion Island. The sharing of knowledge and cross-disciplinary expertise within this partnership will foster innovation and research.

This project builds upon the doctoral work of Raphaël Gass, which led to the development of a dynamic 1D physical model of a PEM cell with auxiliaries, named AlphaPEM, serving as a building block for a fuel cell digital twin. Based on this model, a control strategy for inlet humidity was formulated, theoretically enabling a 60% increase in cell power output or a 15% improvement in efficiency.

The OPUS-H2 project advances this work through five specific objectives:

1. Development of the digital twin and inlet humidity control strategy by adding new functionalities to AlphaPEM.

   • The first aim is to improve the accuracy of the AlphaPEM model by enabling it to simulate additional physical phenomena. Six tasks are implemented to achieve this:
     • refining the model simulating electrochemical impedance spectroscopy (EIS) curves,
     • adding a thermal phenomena model to AlphaPEM,
     • incorporating the microporous layer (MPL) into the PEM cell modeling,
     • using improved auxiliary control tools,
     • increasing the spatial dimension of the single-cell model to 1D+1D,
     • precisely characterizing multiple cells forming a stack.
   • The second aim is to enhance the inlet humidity control strategy developed in previous work. Three tasks are implemented to achieve this:
     • using improved tools for controlling operating conditions,
     • further developing the theory on the limiting liquid water quantity (slim), established in prior work, linking voltage drop at high current densities, liquid water content in the cell, and its operating conditions,
     • refining the inlet humidity control strategy based on the results of this action.

2. Conducting experiments on test benches to validate AlphaPEM and verify performance gains obtained through simulations.

   • The objective is to perform experimental tests on the European partner’s equipment to validate AlphaPEM improvements and the proposed inlet humidity control strategy. Three tasks are implemented to achieve this:
     • generating polarization and EIS curves under different fixed operating conditions on near-single-cell stacks,
     • generating polarization and EIS curves under model-controlled operating conditions on near-single-cell stacks,
     • repeating tests on stacks of around one hundred cells.

3. Integration of models into the digital twin to estimate cell degradation state and remaining system lifespan.

   • The objective is to enable AlphaPEM to account for the current degradation state of an experimental stack and incorporate this impact into the results. Two tasks are implemented to achieve this:
     • integrating a model to estimate electrochemical surface area (ECSA) degradation in the catalytic layer into AlphaPEM,
     • integrating a model to calculate the system’s remaining useful life (RUL).

4. Development of model-based control strategies to maintain optimal performance and reduce degradation over the cell’s lifetime.

   • The objective is to apply the theory produced in the objective 3 to create an operating condition control strategy that maximizes performance and minimizes future degradation in an aged stack. Two tasks are implemented to achieve this:
     • developing a control strategy for operating conditions, based on AlphaPEM, to maintain maximum performance of an aged stack at all stages of its life,
     • developing a control strategy for operating conditions, based on AlphaPEM, to minimize future degradation of an aged stack at all stages of its life.

5. Conducting accelerated degradation experiments on test benches (single cells and stacks) to validate digital twin enhancements and formulated control strategies.

   • The objective is to perform experiments on the European partner’s test benches to validate the proposals from objectives 4 and 5. Three tasks are implemented to achieve this:
     • conducting accelerated degradation experiments without modifying operating conditions on near-single-cell stacks,
     • conducting accelerated degradation experiments with operating condition control strategies on near-single-cell stacks,
     • repeating tests on stacks of around one hundred cells.