I’d designed few alcohol burners in the past, and they’d all depended on using metal rods or shims to vaporize the fuel. One end of the metal would be submerged in fuel while the other end would be in contact with the flame, thus conducting heat back into the fuel and generating combustible gas in situ. A benefit of this approach is that much more power is generated due to the pressure and mixing with air. Because of this, the alcohol burner has become a useful part of my toolkit.
Recently I spent an hour or so reading up on Bunsen’s design of his gas burner. Though a Bunsen burner relies on pressure from the gas line rather than generating its own pressure, some of the concepts are nonetheless helpful in improving my own design. Incorporating some of Bunsen’s ideas, I came up with yet another alcohol burner design: this one allows fresh air to be drawn into the flame by the Venturi effect, thereby improving efficiency and power output. The result is a clean and non-luminous flame.
Here are a couple of pictures of the burner in action. In the first, it is burning 70% ethanol available at most pharmacies; in the second, it is burning 100% acetone. I also tried 100% ethanol, but the flame is barely visible; it works very well, but it is not worth photographing…
70% ethanol: the flame is clean and efficient
100% acetone: perhaps there is much more acetone gas than there is air to mix with it
That is rather cool!
Does burning 100% ethanol still produce much heat?
Yes; 100% ethanol burns very cleanly and dimly. The luminous acetone flame is due to partially-combusted carbon (soot) glowing in the heat.
Hey, I am doing a large-scale research project to be entered into a competition. I will be measuring the different energy contents of fuels including ethanol, methanol, and butanol. I really like your design and it looks like an efficient way of burning the fuels to record the energy output. Could you possibly teach me on how to construct it?
Hey Brycen, I’d documented an earlier revision in images. The only difference is that the metal insert is shorter and there’s no airflow control mechanism. Keep in mind that this design optimizes power output, not necessarily efficiency. If you need to know more, please feel free to ask. I’d love to know how your research turns out!
Thanks a lot. It has been really difficult trying to find a good way to burn these alcohols so this will really help. I’ll definitely let you know how it turns out.
Also, I am not exactly sure about the bottom panels of the picture. I believe this is the airflow control mechanism? Are the corners you cut (bottom left panel) just supports that go in the airflow holes?
I see what you’re talking about. The little glass vial has a slightly constricted mouth, and the metal tube fits snugly against the inside-rim. When inserted, the tube segregates the vial volume into the space within the tube, and the space between the glass wall and the tube. The notches are cut on the bottom of the tube, to allow fuel to flow freely between the two compartments.
On top, I have cut windows into the tube. These extend from outside the vial to slightly below the constriction. The outside part of the windows allow for the Venturi effect; the inside part equalizes the pressure between the two compartments, again helping fuel flow between them. The so-called airflow control basically adjusts the size of the outside-windows; it did not work so well for me.
If your vial doesnt have a constricted mouth, I reckon it’d still work — the metal would just press right against the glass. The glass would absorb quite a bit of heat from the insert, so I’d recommend using Pyrex/borosilicate glass; it may also take longer to heat the fuel. Alternatively, you might be able to use a freestanding tube that is narrower than the vial.
To light the burner, fill it almost to the brim with fuel and ignite it using a lighter through a window. It’d burn slowly for a few seconds, and come to life when the fuel is warm enough. Be careful.
Oh yeah… don’t use Rockstar cans; they’re coated with this layer of plastic that really starts smoking/stinking following ignition. I hope this helps.