Fugitive emissions from a residential natural gas system and appliances operating on hydrogen-blended natural gas (HBNG) fuels
Bibliographic record
Abstract
Methane/hydrogen leaks are tested for four appliances and three pipework sections found in post-meter natural gas installations with 5% and 20% hydrogen using a static flux and pressure drop test method. Appliance emissions ranged from 0.75–37.1 mg CH 4 h -1 when measured shortly after the appliance had been turned off and 0.29–5.9 mg CH 4 h −1 after the appliance had been turned off for 8 h. Appliance leakage testing must take into account these two different leak rate periods. Adding hydrogen decreased methane emissions 1.12–36.99% for a 5% H 2 blend and 1.61–68.78% for a 20% blend. Pipework sections leaked less although a steel/PTFE piping section leaked 101.85 mg CH 4 h −1 . Observed hydrogen leakage was 4–4.5 vol% for the 5% blend and 13–14 vol% for the 20% blend. This suggests that HBNG mixtures do not leak at a significantly greater rate than natural gas.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".