LAUSR

Abstract Air-assisted atomization of the sprays produced by injecting different types of highly viscous pyrolysis oils are studied. Different breakup and atomization regimes are characterized using the long distance microscopic imaging technique. The high resolution imaging reveals detailed underlying two-phase interactions in pyrolysis oil injection that are found unlike other conventional liquid fuels. Several cases of droplet size characterization are carried out using the Malvern’s laser diffraction measurements under variable liquid flow rates, atomizing air flow rates and oil preheating temperatures. The time-averaged and high resolution instantaneous images reveal that the highly viscous nature of pyrolysis oils prevent the instability mechanisms from efficiently atomizing the liquid. The present broad set of measured data suggest that the atomization quality of pyrolysis oils can be optimized by applying a combination of liquid preheating and air-assisted atomization. The flow visualizations reveal the transition from ligament-dominated two-phase flow field into fully atomized sprays when proper oil preheating temperatures and sufficient atomizing air flow rates are provided. Visualized observations are quantitatively verified using the droplet size distribution measurements as well as the Sauter mean diameter (SMD) values for several measurement conditions.