Macroscopic spray characteristics of palm oil-diesel blends in a constant volume combustion chamber

740-747Concern with fossil fuel depletion and environmental degradation promotes the use of renewable energy sources in particular bio-fuel for automotive and power generation. Palm oil in its refined form as cooking oil can be used as fuel in diesel engines. Present study evaluates macroscopic spray characteristics, such as tip penetration, cone angle and spray area using direct injection diesel injector in a constant volume combustion chamber. Palm oil blend with diesel at 20, 40, 60, and 80 % as well as pure palm oil (100 %) and diesel were tested separately using direct visualization technique. Spray developments were investigated at elevated injection pressure starting from 20 MPa (original setting) to 30 and 34 MPa (maximum pressure). Experimental results for palm oil blends show that, spray development process is highly affected with increasing palm oil in the blend. Spray tip penetration and cone angle of blends were found to decrease by about 50 and 30 % respectively compared to diesel fuel. At elevated injection pressures, spray characteristics of the blends show significant improvement. Tip penetration and spray area for P20 at 34 MPa were comparable to diesel at its original injection pressure setting. Moreover, blends average cone angles were found larger at 30 MPa, by about 14.93, 11.47, 7.34 and 1.84 % for P20, P40, P60 and P80 respectively. For P20, 34 MPa injection pressure is sufficient to display spray characteristics similar to diesel, but require higher than 34 MPa injection pressure for other blends