Thermal stability and coking propensity assessment of alternative aviation turbine fuels using a novel experimental methodology
Bibliographic record
Abstract
Aviation jet fuel is an effective cooling medium and it is routinely used in cooling systems on board aircraft; however jet fuel’s heat sink capabilities are limited by its thermal oxidation stability characteristics. When the fuel is heated to higher temperatures, which is referred to as being thermally stressed, liquid phase chemical reactions take place in the fuel that break certain fuel components down and form solid precipitates that are eventually deposited onto the walls of the fuel passages in a process called coking. Coking could be detrimental to the engine operation and jet fuel specifications include an entry for thermal oxidation stability requirements. We conducted experiments to assess the thermal stability of alternative jet fuels using a new thermal stability test rig developed recently. The experimental apparatus consists of a preheating portion and a test section with two different temperatures and residence times mimicking the conditions of the fuel during as it is used as a coolant and as it flows through the injector nozzles. Assessment of the thermal stability of the fuels was done by pressure drop measurements across the heated test section and by a carbon burnoff apparatus. Two conventional and two alternative jet fuels, whose physical and chemical properties had been characterized in detail, were used in the experiments. The experimental data with alternative jet fuels on the new test rig indicated that the rig has the potential to assess thermal stability characteristics of alternative jet fuels. In the carbon burnoff tests, the alcohol-to-jet fuel, BJ1, produced the least amount of coke deposits. BJ2, which is BJ1 blended with 30 % mesitylene, yielded higher deposits than BJ1 but still less than a conventional Jet A fuel, JF1. The results from two methods of coking assessments have some differences, but generally agree qualitatively. Hence the apparatus could be used for assessing the thermal stability of potential alternative aviation turbine fuels. The described methodology can be further fine tuned to be used as a benchmark test apparatus for thermal stability and coking propensity assessment of conventional and alternative aviation turbine fuels, in addition to being a research platform. • Experimental apparatus that can be used as a screening tool for assessing the thermal oxidative stability of sustainable aviation fuels as well conventional jet fuels. • Proof-of-principle experiments with two conventional and two sustainable aviation fuels. • Two different methodologies to evaluate the oxidative thermal stability; a pressure drop based assessment through a test section and a carbon burnoff assessment by oxidizing the coking deposits.
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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".