Risk Assessment of Mildly Flammable Refrigerants with los GWP for Heat pump
Bibliographic record
Abstract
Given the growing demand for cooling, and taking into account the impact of global warming associated with cooling technologies the global climate commitment to reduce the impact of fluorinated gases and the regulations controlling their use in the European Union has increased . This thesis investigates new refrigerants that have been recently proposed to meet the demands of the heat pumps in the refrigeration industry, which must satisfy the legislative requirements of the F-gas Regulation and facilitate meeting the goals of Montreal and Kyoto Agreement. The fluids R32, R1234ze, R1234yF, R452b and R454b have been theoretically analyzed in comparison with the commonly used fluorinated refrigerant in heat pump: R410A. To compare these refrigerants, an excel sheet has been used to calculate the COP for the different cases studied using the REFPROP computer program to know the thermodynamic data of each fluid. The cases studied are the three different heat pump applications : radiators, radiant floor and fan coil and it has been studied for an evaporator temperature range of -15 to 12 ºC, i.e. the COP has been calculated for eighteen different situations. For all of them, the same conclusion has been concluded: all these five proposed fluids have a higher COP than the fluid to be replaced, R410A. It based on this COP for all the cases studied, the best fluids are R454b and R1234Ze(E). Choosing the fluid R454b as the best alternative because its latent heat and vapour density are higher that R1234ze(E) and therefore the flow and size of the pump is smaller, which generally translates into economic savings. However, this refrigerant shows flammability characteristics. For this reason, this paper is checked the fluid risk by a risk assessment. For this assessment two scenarios are analyzed by numerical model, Plume Model: outside and inside of 20 m2 scenario using a 50 kW heat pump. Concluding on the one hand, that in outside conditions a leak would not enter ignition due to the concentration obtained is less than the minimum necessary. In addition from 200 meters of distance the concentration of this fluid would be zero. And that in the hypothetical case that a jet fire takes place is observed that from 10 meters of the leak there is no more radiation. On the other hand, for the room scenario the calculated concentration would be 550 g/m3. This concentration is higher than the acute toxicity exposure limit (435 g/m3) so it is not safe for a human being to work in the situations described.
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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 | 0.002 | 0.004 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".