Emissions Analysis for a Hydrogen-Fueled Low-Pressure-Ratio Split-Cycle Engine
Bibliographic record
Abstract
<div class="section abstract"><div class="htmlview paragraph">Recuperated low-pressure-ratio split-cycle engines represent a promising engine configuration for applications like transportation and stand-alone power generation by offering a potential efficiency as high as 60%. However, it can be challenging to achieve the stringent NOx emission standard, such as Euro 6 limit of 0.4 gNOx/kWh, due to the exhaust cylinder high intake temperature. This paper presents experimental investigation of hydrogen-air combustion NOx emissions for such engines for the first time. Experiments are carried out using a simplified constant-volume combustion chamber with glow-plug ignition. Two fuel injection techniques are performed: direct injection and injection via a novel convergent-divergent injector. For the direct injection scenario, NOx levels are unsatisfactory with respect to the Euro 6 standards over a range of operating temperatures from 200 °C to 550 °C. Recorded NOx levels can reach twice the permissible limit which necessitates the implementation of after-treatment techniques. Interestingly, NOx emissions are found to be less by around 50% in the case of the novel injector. The enhanced fuel-air mixing mechanism using the convergent-divergent injector increases the ignition delay and shifts the combustion flame towards the premixed conditions and results in lower NOx levels.</div></div>
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.003 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| 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 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".