Low-GWP flammable refrigerants and fire risk: The importance of leakage-induced vs reaction-influenced scenarios
Bibliographic record
Abstract
HFCs became the predominant refrigerant type after the Montreal Protocol ban on CFCs and HCFCs due to ozone depletion characteristics. Whilst HFCs do not affect the ozone layer, they have significant global warming potential . Thus, the Kigali Amendment established a global phase-down of high-GWP HFCs. Low-GWP alternatives for applications in residential environments include hydrocarbons, HCs, such as R290, propane. The HCs present, however, higher flammability characteristics. Hence, international standards limit their allowable charge in residential applications. In 2022 these standards eased certain limits focusing on leakage control within closed spaces. Leakage of flammable refrigerants has been considered the primary fire hazard in research and regulations on this topic. Conversely, the reaction of components filled with refrigerants to an independent fire has not received the same attention, despite their key role in the energy transition. This study reviews the current research on the fire risk of flammable refrigerants and the relevant regulatory approach. The review and the analysis of relevant empirical evidence from past accidents highlight the importance of fire reaction compared to leakage hazards. The yearly probability of a leaked refrigerant ignition is seven orders of magnitude less likely than an independent fire. The heat release rate from components engulfed in fire is not negligible and refrigerants can increase it. Data show that external refrigerant units may support fires on building façades and involve combustible thermal insulation . Finally, novel event trees for quantitative fire risk assessment and possible mitigation measures are provided.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.003 | 0.009 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.002 | 0.003 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".