Application of Carbon Dioxide in a Transcritical Refrigeration Cycle
Bibliographic record
Abstract
During the last century, the refrigeration industry was forced to change refrigerant technology due to commitments to the Montreal protocol. The industry is redesigning technology towards the application of new environment friendly refrigerants that may be used for a longer period. Refrigerants should be chlorine free, which means that they do not have impact on the ozone layer, and at the same time they should have low global warming potential. Emphasis in this paper is given to the use of carbon-dioxide R744 and ammonia R717 because of their low impact on the atmosphere. The cascade system technology is known with CO2 as the refrigerant in the first stage and NH3 as the refrigerant in the second stage of the cascade. This paper elaborates the use of CO2 in the transcritical area, i.e. above the critical point where there is no vapour condensation. The paper deals also with problems connected with high working pressure of CO2, thermodynamic properties and design of transcritical heat pumps and their components. Compared to other refrigerants, CO2 has one specific property: low critical temperature 31, 1 °C at 73, 8 bar. The operating pressure for gas cooling will be extremely high, above 100 bar. In the subcritical area the enthalpy change is influenced by the temperature change, while in transcritical area enthalpy change is affected by pressure. In the transcritical area, the coefficient of performance may be controlled by the refrigerant pressure after compression.
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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".