A Comparison of Air-Blast and Flow-Blurring Injectors Using Phase Doppler Particle Analyzer Technique

Abstract

Recent research on biofuels for power generation has typically focused on biodiesel because the biodiesel feedstrock, e.g., vegetable oil, poses significant combustion problems related to poor atomization. Existing injectors cannot effectively atomize high viscosity fuels such as vegetable oil. However, a new, novel flow-blurring (FB) injector concept has shown promise in overcoming the atomization problems. In this study, a FB injector is compared to a commercial air-blast (AB) injector operated with water at ambient conditions of temperature and pressure. Laser sheet visualization and Phase Doppler Particle Analyzer (PDPA) systems are used to obtain the spray characteristics for a range of air to liquid (ALR) ratios. Results show significant difference in distributions of Sauter Mean Diameters (SMDs), and mean and root-mean square axial velocity for the two injectors operated at a fixed ALR. In comparison to the AB injector, the FB injector produced spray with smaller SMDs, a smaller SMD range over the spray volume, higher RMS and mean axial velocities in the center region, and a compact spray with spray angle nearly independent of ALR. Results show that the FB injector is an effective way of atomizing liquids at relatively low ALRs compared to a traditional AB injector, without the additional pressure drop penalty.

Novel Combustion Concepts for Sustainable Energy Development

“…8 for ALR = 2.5 (Simmons et al 2009;Simmons and Agrawal 2011). 8 for ALR = 2.5 (Simmons et al 2009;Simmons and Agrawal 2011).…”

Effects of injector tip design on the spray characteristics of soy methyl ester biodiesel in a blurry injector

“…Previous studies compared experimentally a flow blurring injector with a commercial airblast injector and showed that the flow blurring injector produces a finer spray than the airblast injector for equivalent conditions, whereas requires lower energy input or lower pressure drop in the atomizing air line [36,37]. Combustion experiments show that for a given equivalence ratio, heat release rate, and atomizing air-to-liquid mass ratio, the flow blurring injector produced three to five times lower NO x and CO emissions in diesel and kerosene flames, compared to the airblast injector [35].…”

Measurements in a Combustor Operated on Alternative Liquid Fuels

“…Previous detailed phase Doppler particle analyzer (PDPA) measurements show that the FB injector produces finer spray than that produced by an AB injector at the same atomizing air and liquid mass flow rates. Compared to AB atomizer, the FB injector requires lower energy input since it incurs a lower pressure drop in the atomizing air line [15][16] . For a given overall equivalence ratio, heat release rate (HRR) and atomizing air-to-liquid fuel ratio (ALR), FB atomization in a swirl-stabilized combustor resulted in three to five times lower CO and NOx emissions in diesel and kerosene flames compared to those with AB atomization 17 .…”