Benzin ve Alkol Yakıtları İçin Yağ Filmi Kaynaklı HC Emisyonlarının Matematik Modellenmesi

Silindir cidarları üzerindeki yağ filmi, hidrokarbon (HC) emisyonlarının oluşmasındaki ana kaynaklardan biri olarak bilinmektedir. Bundan dolayı sunulan çalışmada; bir buji ateşlemeli motorda benzin, etanol ve metanol kullanılması durumunda yağ filmi içine emilen/salınan yakıt miktarı sayısal olarak incelenmiştir. Bu amaç için termodinamik esaslı bir çevrim modeli geliştirilmiş ve ardından söz konusu modele yağ filmi kaynaklı HC’lerin oluşumunu hesaplayan bir model eklenmiştir. Yağ filmi tarafından emilen/salınan etanol ve metanol yakıtının benzinden daha düşük seviyede olduğu görülmüştür. Bu farklılığın en önemli parametresi çözünürlükle ilgili olan Henry sabiti olduğu tespit edilmiştir. Düşük motor devirlerinde yağ filmi yakıt buharı etkileşimine daha uzun süre tanındığı için emilen/salınan HC miktarları artmıştır. Artan sıkıştırma oranı ve giriş basıncı ile birlikte emilen/salınan HC miktarları artmıştır

Anahtar Kelimeler:

Yağ filmi, Henry kanunu, HC emisyonları, SI motoru

Mathematical Modeling of HC Emissions Released by Oil Film for Gasoline and Alcohol Fuels

Oil film on cylinder liner has been suggested as a major source of engine-out hydrocarbon emissions. So in the present study, the rate of absorption/desorption of the fuel in the oil film has been investigated numerically in a spark ignition engine by using gasoline, ethanol and methanol fuels. To aim this purpose, a thermodynamic cycle model has been developed and then a mathematical modeling for the rate of absorption/desorption of the fuel in the oil film has been developed and adapted for this thermodynamic cycle model.It was seen that the absorption/desorption mechanism of ethanol and methanol into the oil film were lower than gasoline. It was determined that the most dominant parameter of this difference was Henry’s constant, which was related to solubility. As interaction time of oil filmfuel vapor was longer at low engine speeds, the quantities of HC absorbed/desorbed increased. The quantities of HC absorbed/desorbed increased with increasing inlet pressure and compression ratio

Keywords:

Oil film, Henry’s Law, HC emission, SI engine,

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Makale 21.05.2012 tarihinde alınmış, 03.11.2012 tarihinde düzeltilmiş, 09.11.2012 tarihinde kabul edilmiştir.