Theoretical Exergy and Second Law Analysis of Vapour Compression Refrigeration System with Refrigerants of Low and High Global Warming Potential
Bibliographic record
Abstract
Selection of refrigerants for a refrigeration device depends on many factors like operating temperature range, pressure ratio, toxicity, chemical stability etc. However the criterion, over past few years has shifted to Ozone Depletion Potential (ODP) and GWP. As discussed (United Nations Montreal protocol, 1987) refrigerants with Chlorofluorocarbon (CFC) and Hydro chlorofluorocarbon (HCFC) were proposed to phase out as they had high ODP. Their replacements were sought in the form of Hydro fluorocarbon (HFC), but they were found to have high GWP. Thus seen in context of environment, zero ODP and low GWP refrigerants are need of the hour. Exergy in place of energy is used for analysis as it shows the degradation of energy value and helps in minimization of entropy generation. Various researchers have suggested different low GWP refrigerants as replacements for CFC, HCFC and HFC. Chaudhari et al. used R290 as a replacement for R22 and found that the COP value obtained for R290 was very close to that of R22. (Agrawal, N., 2017.) tested zeotropic blend of R290 and R600a in domestic refrigerator as a substitute to R134a and found Structure zeotropic blend was better in context of COP and compressor power. In other study Gill J.et al. carried energy analysis of VCR system with mixture of R134a and LPG and found the COP of mixture was higher. Apart from this some researchers like Paula de et al. used exergy investigation for checking the feasibility of hydrocarbons. (Arora A., 2011). carried exergy analysis and concluded that R507A is a better choice to replace R502 against R404a . In another study Joibari et.al., conducted exergy analysis for a domestic refrigerator with R600a and it was concluded that charge required for R600a was 66% less than R134a. There are many studies which analyzed alternate refrigerants based on environment and energetic approach . However in the presented work authors have done exergy analysis of VCR system and calculated various performance parameters and compared the results obtained for different refrigerants. On basis of literature survey the researchers have presented the results of studies in which parameters like COP, Exergy destruction, Exergy efficiency, second law efficiency and Exergy destruction ratio (EDR). They are calculated and their variation with ambient temperature (To) and evaporator temperature (Te) is studied.R600a is found to be the best replacement of R134a in terms of COP, second law efficiency and exergy destruction ratio. Other hydrocarbons like R290 and R1270 have performance close to R134a but are far better in ODP and GWP.
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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 | 0.001 |
| 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".