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In the present investigation, tests were carried out to evaluate exhaust emissions of a turbocharged indirect injection diesel engine fuelled with diesel - biodiesel blends. The vehicle was Euro III compliant, fuelled with a typical diesel fuel and used frying oil methyl ester blends at proportions of 2, 5, 10, and 20% respectively. Based on the New European Driving Cycle (NEDC), regulatred and unregulated exhaust emissions were determined over a chassis dynamometer. The use of biodiesel resulted into a significant decrease of HC emissions. NOx and CO emissions exhibited a decreasing trend with the addition of the biodiesel. On the contrary, higher levels of PM emissions were observed. For carbonyl compounds, emissions of acetaldehyde were significantly increased with formaldehyde showing a slight increasing trend.

In this study, the transesterification process of 4 different vegetable oils (sunflower, rapeseed, olive oil and used frying oil) took place utilizing ethanol, in order to characterize the ethyl esters and their blends with diesel fuel obtained as fuels for internal combustion engines. All ethyl esters were synthesized using calcium ethoxide as a heterogeneous solid base catalyst. The ester preparation involved a two-step transesterification reaction, followed by purification. The effects of the mass ratio of catalyst to oil, the molar ratio of ethanol to oil, and the reaction temperature were studied on conversion of sunflower oil to optimize the reaction conditions in both stages. The rest of the vegetable oils were converted to ethyl esters under optimum reaction parameters. The optimal conditions for first stage transesterification were an ethanol/oil molar ratio of 12:1, catalyst amount (3.5%), and 80 °C temperature, whereas the maximum yield of ethyl esters reached 80.5%.