کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
241267 1427928 2007 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Interpreting the influence of fuel spray impact on mixture preparation for HCCI combustion with port-fuel injection
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Interpreting the influence of fuel spray impact on mixture preparation for HCCI combustion with port-fuel injection
چکیده انگلیسی

This paper addresses the influence of fuel spray impact on fuel/air mixture for combustion in port-fuel injection engines. The experiments include time resolved measurements of surface temperature synchronized with PDA measurements of droplet dynamics at impact and were conducted to quantify the effects of interactions between successive injections on the mixture preparation for combustion in homogeneous charge compression ignition (HCCI) engines. Analysis shows that, during engine warm up, the heat transfer over the entire valve surface occurs within the vaporization-nucleate-boiling regime and the local instantaneous surface temperature correlates with the dynamics of droplets impacting at the same point. A functional relation is found for the heat transfer coefficient, which also describes other experiments reported in the literature. Similarity does not hold after the engine warms up because heat transfer and droplet vaporization at the surface are dominated by multiple interactions between droplets arisen from diverse heat transfer regimes. However, results evidence the existence of a critical surface temperature which sets a transition between overall heat transfer regimes dominated by local nucleate boiling at lower temperatures and by local intermittent transition regimes at higher temperatures. The heat transfer within the overall nucleate boiling regime is shown to be due to a thin film boiling mechanism leading to breakdown of the liquid-film at a nearly constant surface temperature, regardless of injection frequency or any other spray conditions. While at low frequencies this regime is not limited neither by the delivery of liquid to the surface, nor by the removal of vapour from the surface, at higher frequencies it is triggered by enhanced vaporization induced by piercing and mixing the liquid film. The results further evidence the important role of spray impingement for mixture preparation as required for HCCI.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Proceedings of the Combustion Institute - Volume 31, Issue 2, January 2007, Pages 2205–2213
نویسندگان
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