Abstract
The effect of biodiesel addition to diesel on engine performance, combustion, and emissions were studied in a turbocharged, high-pressure common rail diesel engine. Biodiesel/diesel blends with different biodiesel fractions were used and compared with neat biodiesel and diesel at different engine loads and speeds. The results show that the brake thermal efficiency increases slightly as biodiesel is added to diesel. Exhaust gas temperature is not significantly affected at low engine speeds and decreases gradually at high engine speeds with an increase in biodiesel fraction. Fuel injection includes both pilot and main injections. Diesel and biodiesel give a similar start to the heat release. The first peak in the heat release rate for biodiesel is lower than that of diesel, while the second peak is higher for biodiesel. The heat release rate curve for biodiesel indicates that the use of biodiesel increases thermal efficiency and NO x emission compared to that of diesel especially at high engine loads. Hydrocarbon and CO emissions maintain very low values and little variation is seen for the different fuels. CO2 emission decreases with increasing biodiesel fraction in the blends. The level of NO x emission decreases slightly at low engine loads and increases at high engine loads with increasing biodiesel fraction. Biodiesel reduces particulate matter (PM) emission significantly and PM reduction effectiveness is increased at high engine loads and/or speed. The oxygen in biodiesel plays a key role in reducing PM emission. Biodiesel/diesel blends can improve performance and decrease emissions for turbocharged, high-pressure common rail diesel engines.
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