Optimization of Pressure-Swirl Atomizer for a Burner Retrofit

Optimization of Pressure-Swirl Atomizer for a Burner Retrofit

en

This study documents several ways to reduce drop size in spray of a spill-return type pressure-swirl atomizer (PSA) for a waste oil burner. In the first part, liquid breakup and spray microstructure of PSAs was documented using spray photography and Phase-Doppler Anemometry (PDA) on a cold test bench at different loads. Then factors that affect the spray characteristics, such as: (1) nozzle design and dimensions, (2) operational conditions and (3) physical properties of atomized liquid, were analysed based on a literature survey. According the analysis, several geometrical factors were chosen for design of six nozzles with modified geometry that were probed using PDA. The literature data analysis shows that a modification of rheological properties of fuel used, namely its heating-up, would significantly reduce D32 mainly due to a viscosity change. Our tests show that doubling the inlet pressure with additional reduction of exit orifice size to keep flow rate would drop D32 by 28 – 33%. The simplest and the most cost efficient way is an optimization of the internal nozzle geometry, which according to our tests, leads to a reduction of D32 by about 7%.

This study documents several ways to reduce drop size in spray of a spill-return type pressure-swirl atomizer (PSA) for a waste oil burner. In the first part, liquid breakup and spray microstructure of PSAs was documented using spray photography and Phase-Doppler Anemometry (PDA) on a cold test bench at different loads. Then factors that affect the spray characteristics, such as: (1) nozzle design and dimensions, (2) operational conditions and (3) physical properties of atomized liquid, were analysed based on a literature survey. According the analysis, several geometrical factors were chosen for design of six nozzles with modified geometry that were probed using PDA. The literature data analysis shows that a modification of rheological properties of fuel used, namely its heating-up, would significantly reduce D32 mainly due to a viscosity change. Our tests show that doubling the inlet pressure with additional reduction of exit orifice size to keep flow rate would drop D32 by 28 – 33%. The simplest and the most cost efficient way is an optimization of the internal nozzle geometry, which according to our tests, leads to a reduction of D32 by about 7%.