An experimental study of the effects of fuel injection pressure on the characteristics of a diesel engine fueled by the third generation Azolla biodiesel.

This study focuses on effectively utilizing the biodiesel extracted from Azolla (third-generation biofuel), which is regarded as a renewable energy source, for fueling diesel engines. Biodiesel is unique due to its increased viscosity and different fatty acid composition, which proved difficult to attain better engine performance with a mechanical type injection system. This study expands on the previous investigation in modifying the fuel system when using Azolla biodiesel by using a common rail fuel injection system with wider injection flexibility. Considering the lack of more engine optimization studies for Azolla biodiesel, a parametric study is conducted by changing the fuel injection pressure in the range between 300 bar and 900 bar for diesel engine fueled by B20 (20% Azolla +80% diesel) blend. The experimental engine study revealed that the physical properties of the fuel adversely affect the in-cylinder combustion, which leads to poor engine performance and higher emissions at lower injection pressure (300 bar) for B20 when compared to diesel. As the injection pressure increases, the fuel atomization and other spray characteristics are enhanced and thereby improve the combustion. The Brake Thermal Efficiency (BTE) for B20 at 900 bar injection pressure is 3% higher than the diesel fuel at 300 bar injection pressure under full load conditions. The HC, CO, and smoke emission in the engine exhaust for B20 at 900 bar injection pressure was reduced by 13.3%, 28.5%, and 12.3%, respectively, when compared to diesel. Overall, this study recommends the operation of Azolla biodiesel blend in diesel at 900 bar fuel injection pressure to attain improved engine characteristics.

Computational analysis of turbulence enhancement in a compression ignition engine with modified inlet design.

This study aims to enhance the turbulence of direct injection (DI) diesel engine by modifying the inlet manifold design with an inclined nozzle-like provision angles of 30°, 60°, and 90° along with its regular intake system. Numerical analysis was carried out using the computational fluid dynamics package (STAR-CD libraries of es-ice) to study the flow field and combustion characteristic with the modified intake manifold geometries. The computational investigation was carried out for both single and double pass conditions at 1500 rpm under high-load operating condition (5.2 kW). The computational results showed that the velocity magnitude of modified single pass intake manifold increases by about 10% that results in higher turbulence even near the point of fuel injection. Through the modification in the inlet manifold, the combustion parameters such as in-cylinder pressure and in-cylinder temperature are increased as compared to the standard manifold for the same quantity of fuel injected per cycle. In summary, the 60° modified manifold with a single pass shows better combustion and emission characteristics compared to that of regular inflow manifolds due to the improvement in turbulence levels.