Experimental Investigation on Emissions Characteristics from Urban Bus Fueled with Diesel, Biodiesel and an Oxygenated Additive from Residual Glycerin from Biodiesel Production

The aim of the study was to assess the influence of the addition of an oxygenated additive (a mixture of mono-, di- and triacetylglycerol obtained from residual glycerin within the biodiesel production scheme) on the specific fuel consumption and exhaust emissions of a EURO 3 diesel bus during its daily route through the city. To do this, the urban bus was fuelled with five fuel blends of diesel (D), biodiesel (B), additive (A) and heptanol as co-surfactant (H). A portable emissions measurement system was used to measure the exhaust gases while an engine exhaust particle system with a dilution system, both installed on the urban bus, was used for nanoparticles measurement in actual operating conditions through the city of Seville. Results showed that B95A5 (95%v/v biodiesel, 5%v/v additive) and B90A10 were the blends that most increased NOx emissions (by 24.12% and 9.85%, respectively) compared to D100. On the other hand, B47.5D47.5A2.5H2.5 was the blend that most reduced total particle number (by 31.6%) and NOx emissions (by 12%). All in all, the oxygenated additive can be efficiently blended with biodiesel to reduce particle emissions from engines without diesel particle filter, such as those in urban buses in many European cities