Improved experimental method for measuring gas diffusivity through thin porous media
Bibliographic record
Abstract
Gas diffusion through porous media is critical for the high current density operation of a polymer electrolyte membrane fuel cell, where the electrochemical reaction becomes rate limited by the diffusive flux of reactants. Precise knowledge of the diffusivity through various components in a fuel cell is necessary for accurate modeling and analysis. However, many experimental measurements of diffusivity in literature have high measurement uncertainty. In this study, an improvement to the accuracy of the Loschmidt cell method is presented for measuring the diffusivity through materials with a submillimeter thickness. The diffusivity through various gas diffusion layers (GDLs) is measured, and the relative differences between GDLs are explained using scanning electron microscopy and the method of standard porosimetry. The experimental results from this study and others in current literature are used to develop a generalized correlation for the diffusibility as a function of porosity in the through‐plane direction of GDLs. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1409–1419, 2013
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".