Unified Approach to Exergy Efficiency, Environmental Impact and Sustainable Development for Standard Thermodynamic Cycles
Bibliographic record
Abstract
The exergy efficiency of three standard thermodynamic cycles, i.e., Brayton, Rankine and Otto cycles, are developed and the corresponding analytical equations are derived accordingly. The resultant expressions are applied to typical operating conditions and numerical results are obtained, when the heat of each engine is supplied by burning natural gas as a fuel with 100 percent theoretical air. A common result is the significant effect of the maximum cycle temperature, which causes an increase of exergy efficiency. It is shown that the compression ratio of the Brayton and Otto cycles, as well as the turbine inlet pressure in a steam power plant, raise the exergy efficiency. Moreover, increasing the ambient temperature has a negative influence on the exergy efficiency in the Brayton and Otto cycles, which occurs due to ambient air fed to these systems, thereby decreasing the deviation of the system from ambient conditions and reducing the exergy efficiency. Further findings include an optimal performance point of the Brayton and Rankine cycle, with a high sustainability and exergy efficiency. For instance, at the optimal operating point of the Brayton cycle with a compression ratio of 8 (or 12 for a second case), the exergy efficiency is 73 (60) percent, CO2 emissions is 530 (590) g/kWh and the sustainability index is 3.8 (2.8). The optimal operating point for an example of a Rankine cycle is found to be 50 percent for the exergy efficiency, with 440g/kWh of emitted CO2 and a sustainability index of two.
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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".