Anti-vapor Lock of a Top-Feed Injector for a Liquefied Petroleum Gas Liquid-Phase Injection Engine
Notice bibliographique
Résumé
The injection spray characteristics and restart operation after hot soaking of a top-feed injector were investigated using liquid-phase injection of liquefied petroleum gas (LPG) in a spark-ignition engine. LPG is one of the well-known gaseous fuels with benefits of emission reduction. The most challenging aspect of the LPG injection system is the phase change of the fuel. LPG inside the pressurized fuel rail is liquid when the engine is in operation. However, it may become gaseous when the fuel pump is turned off. Vaporized LPG inside the fuel rail has to be removed using the fuel return line during the operation of fuel pump before cranking. The top-feed fuel injector does not have a fuel return line in the injector body. The vaporized LPG inside the fuel rail is not removed at the critical conditions and injected at the intake port instead of liquid LPG. However, the injection duration during the engine-start phase is limited, and the fuel amount is insufficient to start the engine. The resulting hot restart problem is very important and must be solved to adapt an injector for LPG liquid-phase injection systems. LPG engine test and flow visualization of the LPG injection system were carried out to investigate the feasibility of the top-feed injector. The LPG temperatures in top- and bottom-feed injection systems were measured and analyzed. Different operating pressures and temperatures of the fuel injection system were tested to identify the injection characteristics after hot soaking using an injection test rig and an engine test bench. The vaporized LPG was successfully removed with a bottom-feed injector. However, in the case of a top-feed injector, the vaporized LPG still remained inside the fuel rail, so that the engine may not be restarted. A modified design of a LPG delivery pipe with a larger volume at higher pressure was suggested to solve the vapor lock problem. A Mie-scattering technique was used to verify the successful liquid-phase injection after hot soaking. Fuel delivery pipe visualization was carried out to measure the position and size distribution of vaporized LPG inside the fuel rail. In the case of a bottom-feed injector, the injection was accomplished at every experimental condition. In the case of a top-feed injector, rail pressure over 1.2 MPa resulted in the need for an overly long injection duration, indicating that the injector solenoid was not powerful enough for such high pressure. The modified LPG delivery pipe was made with 1 × 10 −3 m 3 of volume, and LPG injection pressure was 1.05 MPa. The engine with the modified top-feed fuel injection equipment was successfully restarted after hot soaking.
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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 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| 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 découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».