CFD Study on Selection of Low GWP Participating Gas for a Passive Cooling Skylight
Bibliographic record
Abstract
Abstract Passive cooling and air-conditioning methods are being developed for both night-time and daytime cooling of buildings. A passive cooling skylight under development at Åbo Akademi demonstrated a night-time passive cooling effect of ~ 100 W/m 2 . This depends strongly on the gas used inside the skylight, picking up (long wavelength, LW) thermal radiation via a lower window and after a natural convection transfer inside the skylight, releasing the heat to the sky via an upper window. Proof-of-concept work utilised air, carbon dioxide, ammonia and, for best results, pentafluoro ethane, HFC-125. The 2016 Kigali Amendment to the 1986 Montreal Protocol on HFCs necessitates using a low-global warming potential (GWP) alternative for HFC-125: future refrigeration installations cannot contain a GWP > 150 gas under European regulation. The key gas property is high emissivity/absorption in the LW range 8–14 µm, the “atmospheric window”, thus HFC-152a or HFC-41 could replace HFC-125. CFD simulations (Ansys Fluent 2024 R1) were used to calculate the passive cooling heat fluxes, temperatures, convection flow fields, and transported heat inside the skylight, comparing gases. Results show that HFC-152a (117.8 W/m 2 ) and slightly less so HFC-41 (115.4 W/m 2 ), both with a GWP < 150, can match the performance achieved earlier with HFC-125 (117.3 W/m 2 ).
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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 | 0.000 |
| 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) | 0.000 | 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".