Combustion characteristics of waste-oil produced biodiesel/diesel fuel blends

In this study, wasted cooking oil from restaurants was used to produce neat (pure) biodiesel through transesterification, and this converted biodiesel was then used to prepare biodiesel/diesel blends. The goal of this study was to compare the trace formation from the exhaust tail gas of a diesel engine when operated using the different fuel type: neat biodiesel, biodiesel/diesel blends, and normal diesel fuels. B20 produced the lowest CO concentration for all engine speeds. B50 produced higher CO₂ than other fuels for all engine speeds, except at 2000 rpm where B20 gave the highest. The biodiesel and biodiesel/diesel blend fuels produced higher NO_x for various engine speeds as expected. SO₂ formation not only showed an increasing trend with increased engine speed but also showed an increasing trend as the percentage of diesel increased in the fuels. Among the collected data, the PM concentrations from B100 engines were higher than from other fuelled engines for the tested engine speed and most biodiesel-contained fuels produced higher PM than the pure diesel fuel did. Overall, we may conclude that B20 and B50 are the optimum fuel blends. The species of trace formation in the biodiesel-contained fuelled engine exhaust were mainly C_nH_2n+2, DEP, and DPS. For the B100, B80, B50, and D fuelled engines, C₁₅H₃₂ was the dominant species for all engine speeds, while squalene (C₃₀H₅₀) was the dominant for B20. DEP was only observed in the B100, B80, and B50 fuelled engines in this study. The D fuelled engine showed a higher DPS production for engine speeds higher than 1200 rpm.