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Atmospheric Propane Brazing Torch Experiments

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vtsteam:
Hi Neo --- do you mean a slide restrictor over the air slots? That would just enrich the flame, I think -- which would be useful for settings where the flame was tending to lean out. But I don't think it would concentrate the flame into a smaller space, which is where I want to go.

Maybe you mean something inside the bore -- which is what I'm going to try next -- but that would be a mixer.

I think the key to reducing flame dimensions (and increasing local heat intensity) is better mixing. I think flame size is in inverse proportion to mixing efficiency, and in proportion to exit velocity.

So I would like to slow down the exit speed, and increase the mixing efficiency before the gasses burn. I think they will burn in a smaller space that way. A third consideration would be shaping the gas "bundle" as it exits.

I thin k the commercial practice of a perforated or vaned insert is what does most of the above three things.

Ac tually, if you want to think about it in this way, a hearth also does exactly those same three things. It mixes through turbulence in a smaller space, slows the flame and shapes it. It also insulates and generates IR radiation, but that is an additional help not available in a pure atmospheric torch.

NeoTech:
Hm you are prob right there.. gonna try to make one myself.. i liked the simplicity of that setup. =)

dranoel58:
Hi Guys
Newby and first posting.
Enjoy your topic, been experimenting with a handheld torch/burner myself.
Based mainly on M Porter design, but with added features.

Aiming for single wave combustion (short primary flame)
And knowing that a turbulent flame burns hotter.
I went about it in this way.

Presuming the sizing of the jet/ burner tube i.d./ burner tube length, are O.K.
Found that in free air a stepped flare gives a more stable flame over a bigger range.

At first the flame was too long and laminar, so needed to create turbulance.
Drilled holes 3X near the end of the burner tube, and created a key-hole shape.
By opening a slot, towards the end of the tube.

The i.d. of the flare will cover the key-hole shape holes.
On the inside the holes create turbulance and hence better mixing.

Turbulance speeds up the chemical reaction during combustion.
Thus creating a hotter and more concentrated flame.

Hope this helps.

vtsteam:
Great dranoel58! And welcome to the forum!  :beer:

Do you have any flame pictures? Have you brazed with it?


Also, what is M Porter design?

mattinker:
Hi VT,

A very good book on burners.

Gas Burners for Forges, Furnaces, and Kilns
Michael Porter

Regards

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