I have a white paper somwhere, and they were trying to improved the efficiency of siphon nozzle oil burners, which are still used in a lot of smaller countries to run smaller founderies.
As I recall, the pulsed fuel produced an increase in efficiency of 20-30%.
I have read literature by the head of engineering at Delavan, and he discusses droplet sizes, and such, and the topic of creating the most efficient and hottest burn is not as clean cut as one would imagine.
You would think smaller droplets would provide more surface area, and higher efficiency, but this is not the case.
The most efficient and hottest burning oil burner is the one that produces the largest and hottest surface area on each droplet, regardless of the droplet size.
I played around with my siphon nozzle burner, out of the furnace, and observed the droplets for various fuel flows and compressed air pressures.
I started with 100 psi compressed air, and gradually reduced the pressure, and it seems like the burn is hotter with a lower air pressure, such as 20-30 psi, with a more coarse droplet.
If you reduce the compressed air pressure too much, then the droplets get so large that they do not completely burn before they settle to the ground, and so you get puddling of unburned oil on the ground as you drop below about 20 psi.
I was going to pulse my fuel, but have not had time to try that, and am not sure exactly how to pulse it.
I piston pump seems like it would work; perhaps just an eccentric that strikes a spring-loaded piston rod.
I would think between 30 and 60 Hz, but that is a blind guess.
A few pictures of experiments with various siphon nozzle burners.
I have tried all sorts of burner configurations, including single siphon nozzle burner, dual siphon nozzle dual burner tube, duel siphon nozzles in a single burner tube, etc.
In the end, the single siphon nozzle per burner, with dual burner tubes at 180 degrees I think is the best performer, especially for larger furnaces.
For my furnace, which has an interior of about 13" diameter, and 14" tall, a single siphon nozzle works very well, and it is hard to justify a second burner tube.
And as I have mentioned, I am transitioning to a gear pump burner, just so I can run the furnace at remote shows that don't have compressed air, and don't necessarily have electricity.
The gear pump can be run from a small generator, since it is fractional horsepower (less than 1/4 hp would work).
One thing I have found is that bigger is not better, and more fuel and air is not hotter, but often times cooler.
The trick no matter what burner you use is to create droplets that burn very hot, and introduce precisely the right amount of fuel and air into a give size furnace to get complete combustion inside the furnace.
2.7 gal/hr is about what produces the most heat and the fastest melt for my furnace size, and any more or less runs cooler.
Image 6114 shows the flame produced by the twin 180 degee burners, and the velocity is low, with the flame burning hot and pretty complete very low in the furnace.
.
As I recall, the pulsed fuel produced an increase in efficiency of 20-30%.
I have read literature by the head of engineering at Delavan, and he discusses droplet sizes, and such, and the topic of creating the most efficient and hottest burn is not as clean cut as one would imagine.
You would think smaller droplets would provide more surface area, and higher efficiency, but this is not the case.
The most efficient and hottest burning oil burner is the one that produces the largest and hottest surface area on each droplet, regardless of the droplet size.
I played around with my siphon nozzle burner, out of the furnace, and observed the droplets for various fuel flows and compressed air pressures.
I started with 100 psi compressed air, and gradually reduced the pressure, and it seems like the burn is hotter with a lower air pressure, such as 20-30 psi, with a more coarse droplet.
If you reduce the compressed air pressure too much, then the droplets get so large that they do not completely burn before they settle to the ground, and so you get puddling of unburned oil on the ground as you drop below about 20 psi.
I was going to pulse my fuel, but have not had time to try that, and am not sure exactly how to pulse it.
I piston pump seems like it would work; perhaps just an eccentric that strikes a spring-loaded piston rod.
I would think between 30 and 60 Hz, but that is a blind guess.
A few pictures of experiments with various siphon nozzle burners.
I have tried all sorts of burner configurations, including single siphon nozzle burner, dual siphon nozzle dual burner tube, duel siphon nozzles in a single burner tube, etc.
In the end, the single siphon nozzle per burner, with dual burner tubes at 180 degrees I think is the best performer, especially for larger furnaces.
For my furnace, which has an interior of about 13" diameter, and 14" tall, a single siphon nozzle works very well, and it is hard to justify a second burner tube.
And as I have mentioned, I am transitioning to a gear pump burner, just so I can run the furnace at remote shows that don't have compressed air, and don't necessarily have electricity.
The gear pump can be run from a small generator, since it is fractional horsepower (less than 1/4 hp would work).
One thing I have found is that bigger is not better, and more fuel and air is not hotter, but often times cooler.
The trick no matter what burner you use is to create droplets that burn very hot, and introduce precisely the right amount of fuel and air into a give size furnace to get complete combustion inside the furnace.
2.7 gal/hr is about what produces the most heat and the fastest melt for my furnace size, and any more or less runs cooler.
Image 6114 shows the flame produced by the twin 180 degee burners, and the velocity is low, with the flame burning hot and pretty complete very low in the furnace.
.
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