Effect of Enclosed Flame on Spray Characteristics and Emissions from Preheated Bio-oil Using an Air-blast Atomizer

Global atmosphere pollution has become a serious problem for today. The emissions from the combustion of fossil fuels contribute a notable part to this pollution. Given a wide spread of different biofuels available for combustion applications, the present study concentrates on atomization spray characteristics of vegetable oils. In this study preheated vegetable oil (VO) is used to reduce the kinematic viscosity, and thus, improve atomization. A commercial air-blast atomizer operated at ambient conditions of temperature and pressure is used to atomize the VO. Flame spray characteristics are measured using a laser sheet visualization system and a Phase Doppler Particle Analyzer system. Experiments are conducted for unheated and preheated VO at 100 °C for a given ALR of 2.0 in enclosed flame conditions simulate realistic gas turbine conditions. VO is combusted in an atmospheric pressure burner with air blast atomizer and swirling combustion air around. The mean axial and RMS velocities, SMD and drop size distribution data are acquired. The measurements are taken for preheated VO at 100 °C and 150 °C respectively. The transverse profiles of mean axial velocity showed peaks at the center while they showed a decreasing trend at the outer edges of the spray. RMS axial velocity increases for flame spray compared to cold spray. Higher VO inlet temperatures led to smaller droplets and higher mean axial velocity for a given ALR. Results also suggest that insulated enclosure provide additional heat feedback from the flame to improve the overall spray characteristics, an effect that has been quantified in the present study.