Analysis of Propane Burner Designs
I am a software engineer, not a fluid dynamics engineer, and I was hoping that the people on this forum could answer some questions about a couple designs of propane burners and how they work and what could be improved. The burners in question are high output burners used to power forges and foundries for metal working. They both are naturally aspirated using the venturi principle and a single high pressure jet injector. The first design follows:
Please see attachment Reil.jpg. This design uses a straight across supply tube with a drilled hole for the gas to escape out the side of the tube. The tube can be rotated or moved back and forthe to center the jet in the burner. The main body consists of a 2" to 3/4" bell reducer, an 8" main burner pipe and a slight 10 degree flared nozzle on the end.
Please see attachment Simmons.jpg. This design uses a longitudinally mounted jet tube that ends in the jet tip just inside the bell reducer before the burner end. The main body consists of (from left to right) a back end cap, a pipe that has been drilled out with 24 holes, each 1/2" in diameter. Finally this is followed up by a 2" to 3/4" reduction, a 12" burn tube and a 3/4" to 1" bell reducer used as a flame holder flare.
Both burners take advantage of the venturi effect to mix the gas with air in order to get a clean burn of the fuel and maximum BTU. I personally think that the Simmons burner will produce better overall results for a couple of reasons. (naturally I could be wrong which is why I am posting)
1) The simmons burner creates a trapped and confined low pressure zone inside the ported out pipe. This would result in more consisten airflow into the pipe so long as the total area of the ported holes equals or exceeds that of the cross section of the tube. By contrast, the low pressure zone in the Reil burner wouldnt be trapped but rather only exist at the intake causing it to breathe not as well.
2) The air sucked into the simmons burner will be turbulent due to the path it must take to reach the venturi. This will promote a more throuough mixing of the propane and air.
3) the longer tube could provide greater acceleration of gas and air to produce a more powerful flame. Indeed when I used a .025" jet, the gas velocity was too high and the flame front jumped right off the end. I had to use a .035 tip to reduce the gas speed so the flame front could keep up.
I would be interested in any analysis and comments the members of this forum would have with their vastly superior knowledge in fluid dynamics. I would also welcome any suggestions that could be made to improve either burner.
Thanks for your time.
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