Variations of cetane number of jatropha biodiesel blends with mineral diesel

Abstract

Cetane number (CN)- a prime indicator of diesel fuel quality, is a quantity indicating the combustion behaviour of diesel fuel and compression required for ignition in diesel engines. This study examines the determination of CN of Jatropha biodiesel blends with mineral diesel using their physical properties, and their variations of CN with percentage composition of Jatropha biodiesel in the blends. Jatropha biodiesel, converted through a transesterification process of its oil, is obtained and blended with diesel to obtain blend B10 (10% biodiesel and 90% diesel) on a volumetric basis, at 25 o C ambient temperature and the same basis was employed for blends B20, B30, B40 and B50. The specific gravity and mid-distillation characteristic were obtained using a hydrometer and distillation curve apparatus based on ASTM D1298 and D86 standards respectively. The CN of Jatropha oil, its biodiesel and Jatropha biodiesel blends with diesel were analytically determined, employing the empirical relationship between measured physical properties of a two-variable cetane index equation. The results show that the CN of the Jatropha biodiesel increases significantly (about 29%) after transesterification compared with that of the Jatropha oil. Moreover, the specific gravity and CN of the blends increase with the percentage composition of Jatropha biodiesel in the blends. The CN of Jatropha biodiesel is 44.10, which is 8.7% higher than that of mineral diesel (40.62). It can be implied from the research outcomes that blending Jatropha biodiesel with diesel increases the CN of the blends, thus, could be used as cetane point (number) enhancer.