Researchers at Indonesia’s Institut Teknologi Bandung have compared the effects and performance of biodiesel fuels derived from two different feedstocks of importance to that country—palm oil and jatropha—in a direct-injection diesel engine.
The study, described in a paper presented at the recent FISITA 2006 conference in Yokohama, Japan, by Dr. Iman Reksowardojo, compared five fuels: B10 palm oil biodiesel, B100 palm oil biodiesel, B10 jatropha biodiesel, B100 jatropha biodiesel and petrodiesel.
The tests measured the effects on the injection pump and nozzles, piston crowns and cylinder heads. The tests also measured emissions of NOx and CO, and fuel consumption.
|Parameter||Unit||Palm Oil Biodiesel||Jatropha Oil Biodiesel||Petrodiesel|
|Viscosity||Cst||5.3 (40°C)||3.576 (50°C)||3.15(40°C)|
|Density||g/cm3||0.868 (25°C)||0.8809 (15°C)||0.8253 (40°C)|
|Acid value||mg KOH/g||0.24||0.38||0.06|
Among the results the study found were that:
Fuel consumption. The differences between fuels were not significant, but B10 Jatropha Curcas turned in slightly lower results that the other blends. The researchers assumed this is because the low viscosity, oxygen content and higher cetane number of B10 Jatropha Curcas contributed to better combustion. This result is still under exploration.
CO emissions. CO exhaust gas emissions decreased as the content of biodiesel fuel increased in the blending fuel. B100 Palm emitted more CO than other fuels except Petrodiesel, and the researchers concluded this is a result of the highest viscosity of the fuel leading to poorer atomization.
NOx emissions. B100 Jatropha emitted significantly more NOx than the other fuels. This result is also still under investigation.
Effect on the injection plunger. The additional weight added to the plungers using the biodiesel blends was lower compared to Petrodiesel, with the exception of B100 jatropha biodiesel.
Effect on the injection nozzle. While the weight of all nozzles—B100 Palm, B10 Palm, B100 Jatropha Curcas, B10 Jatropha and Petrodiesel—increased, the higher the biodiesel percentage in the fuel burned, the lower the weight increase of the nozzle. This was attributed to the oxygen content in the biodiesel contributing to improved combustion, resulting in lower deposits in the nozzle. Palm Oil biodiesel nozzles had the lowest weight gain.
Effect on the piston. Although deposits formed in the piston crowns from all the fuels, the deposits resulting from biodiesel use were easier to clean compared to the Petrodiesel.
Effect on the cylinder head. The thickness of the deposits on the cylinder head followed the same trend as the piston crown deposits. Use of B100 jatropha resulted in the lowest amount of deposits.
The team concluded that the results highlighted that the quality of biodiesel and its effect on engine components is determined partly by the raw material of the feedstock.