Mechanistic study on spraying of blended biodiesel using phase Doppler anemometry

Droplet size and dynamics of blended palm oil-based fatty acid methyl ester (FAME) and diesel oil spray were mechanistically investigated using a phase Doppler anemometry. A two-fluid atomizer was applied for dispersing viscous blends of blended biodiesel oil with designated flow rates. It was experimentally found that the atomizer could generate a spray with large droplets with Sauter mean diameters of ca. 30 mm at low air injection pressure. Such large droplets traveled with a low velocity along their trajectory after emerging from the nozzle tip. The viscosity of blended biodiesel could significantly affect the atomizing process, resulting in the controlled droplet size distribution. Blended biodiesel with a certain fraction of palm oil-based FAME would be consistently atomized owing to its low viscosity. However, the viscosity could exert only a small effect on the droplet velocity profile with the air injection pressure higher than 0.2 MPa.

Effect of biodiesel oil composition on droplet size distribution

Droplet size distribution of biodiesel oil with various compositions was investigated in this work. The droplets generated by a two-fluid atomizer were measured by a commercial PDA. It was found that viscosity of the fuel has a strong effect on the drop size distribution. Additionally, effect of air injection pressures applied to atomize the spray was taken into account. Shear force induced by flow field exerts an effect on distribution of biodiesel droplets in atomized spray.