Order of magnitude analysis has been reported in the literature to show the time constants associated with various dynamics in the cell. presented such an analysis, where they found the time constants for gas diffusion in porous media and reaction kinetics to be on the order of a few milliseconds.
As mentioned earlier, including all these effects results in increased computational costs, whereas lower costs are desired for real-time applications.
To this end, many computationally efficient models have been proposed in the literature. developed a 0-D isothermal and dynamic model for system-level control tasks.
Real-time estimation, prediction, and control of cell hydration and temperature distribution is essential for optimizing the performance of polymer electrolyte membrane fuel cells (PEMFCs), as well as avoiding critical conditions and mitigating cell degradation.
These applications necessitate mathematical models that not only run in real time, but also incorporate the important physical phenomena related to water transport and thermal management.
The model is highly efficient, but it does not provide any spatial resolution of the variables.
The simplistic nature of the model limits its predictive capability to a narrow range of operating conditions.
Moreover, these models can easily incorporate the anisotropic material properties of various cell layers, which is especially important in the case of gas diffusion layers (GDLs).
On the other hand, these models are computationally very expensive and do not lend themselves to real-time applications.
Moreover, pseudo 2-D models may be calibrated to account for the channel-land effects through the use of effective resistances at the channel interface with the diffusion media.
In terms of temporal behavior of the fuel cell system, transient models are required to capture various dynamic phenomena in the cell that occur on multiple time scales and have a profound effect on its performance.