Impact of Antioxidant Additives on the Engine Performance and Exhaust Emissions Using Biodiesel made from Jatropha Oil of Eastern Africa Origin

Abstract

Biodiesel’s chemical nature makes it more susceptible to oxidation in comparison to mineral diesel. Biodiesels are doped with antioxidants to increase oxidation stability for long term storage. However, it is quite possible that these additives may affect fuel related properties of biodiesel such as cetane number and kinematic viscosity and also the performance of engine and exhaust emissions. Therefore, this study investigated the effects of antioxidant on the oxidation stability, cetane number and kinetic viscosity of biodiesel made from jatropha oil of Eastern Africa origin. Also, the influence on the performance and exhaust emissions of a four cylinder turbocharged direct injection (TDI) diesel engine. Antioxidant 1, 2, 3 trihydroxy benzene (Pyrogallol, PY), as the most effective antioxidant based on the earlier work of the authors was mixed with the produced Jatropha Oil Methyl Ester (JOME) at different concentrations to improve the oxidation stability. The results showed that, the oxidation stability of JOME increased with the increase of PY dosage. Also, cetane number slightly increased with additional of antioxidant whereas kinetic viscosity was observed to decrease with PY dosage. The brake specific fuel consumption (BSFC) of JOME with antioxidants decreased more than that without antioxidants, but both were higher than that of diesel and diesel/biodiesel blends. No significant effects were observed on the exhaust emissions of a diesel engine running on biodiesel (JOME) dosed with antioxidant PY.