Transient Liquid Water Distributions in Polymer Electrolyte Membrane Fuel Cell Gas Diffusion Layers Observed through In-Operando Synchrotron X-ray Radiography
Bibliographic record
Abstract
In this work, in-operando synchrotron X-ray radiography was used to capture the changes in the liquid water saturation of gas diffusion layers (GDLs) during changes in operating current density. Through in-operando visualizations at high temporal and spatial resolutions, we observed that the liquid water saturation increased with increasing current density. Eventually, a threshold water content in the GDL was reached despite further increases in current density. A time lag between the change in current density and the onset of increasing GDL water content was also observed. Current density consistently reached a steady state value before the GDL water content reached steady state, and the trends in liquid water distributions in the MPL were distinct from, yet influential to the accumulation in the substrate. We present a logarithmic growth function that describes the dynamic changes in GDL water content. The formulation of the GDL liquid water content transient response to changes in operating conditions provides a new metric for designing next generation fuel cell powertrains with fast dynamic responses. Through plane water thickness profiles were also used to show that the water accumulation patterns continued to evolve for up to 15 minutes at the low current density.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".