Detailed Analysis of the Effects of Biodiesel Fraction Increase on the Combustion Stability and Characteristics of a Reactivity-Controlled Compression Ignition Diesel-Biodiesel/Natural Gas Engine
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Résumé
A single-cylinder marine diesel engine was modified to be operated in reactivity controlled compression ignition (RCCI) combustion mode. The engine fueling system was upgraded to a common rail fuel injection system. Natural gas (NG) was used as port fuel injection, and a diesel/sunflower methyl ester biodiesel mixture was used for direct fuel injection. The fraction of biodiesel in the direct fuel injection was changed from 0% (B0; 0% biodiesel and 100% diesel) to 5% (B5) and 20% (B20) while keeping the total energy input into the engine constant. The objective was to understand the impacts of the increased biodiesel fraction on the combustion characteristics and stability, emissions, and knocking/misfiring behavior, keeping all other influential parameters constant. The results showed that nitrogen oxides (NOx) emissions of B5 and B20 without the need for any after-treatment devices were lower than the NOx emission limit of the Euro VI stationary engine regulation. B5 and B20 NOx emissions decreased by more than 70% compared to the baseline. Significantly more unburned hydrocarbons (UHCs) and carbon monoxide (CO) emissions were produced when biodiesel was used in the direct fuel injection (DFI). The results also showed that using B5 and B20 instead of B0 led to an increase of 18% and 13.5% in UHCs and an increase of 88.5% and 97% in CO emissions, respectively. Increasing the biodiesel fraction to B5 and B20 reduced the maximum in-cylinder pressure by 3% and 10.2%, respectively, compared to B0. Combustion instability is characterized by the coefficient of variation (COV) of the indicated mean effective pressure (IMEP), which was measured as 4.2% for B5 and 4.8% for B20 compared to 1.8% for B0. Therefore, using B20 and B5 resulted in up to 34.9% combustion instabilities, and 18.5% compared to the baseline case. The tendency for knocking decreased from 13.7% for B0 to 4.3% for B20. The baseline case (B0) had no misfiring cycle. The B5 case had some misfiring cycles, but no knocking cycle was observed. Moreover, the historical cyclic analysis showed more data dispersions when the biodiesel fraction increased in DFI. This study shows the potential of biodiesel replacement in NG/diesel RCCI combustion engines. This study shows that biodiesel can be used to effectively reduce NOx emissions and the knocking intensity of RCCI combustion. However, combustion instability needs to be monitored.
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Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,002 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,001 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découle