Jan 16, 2011

My alcohol stove

I first heard of alcohol stoves a couple of weeks ago while browsing the forum at backpacker.com. “Alcy stoves” burn denatured alcohol and are meant specifically for boiling water. You cannot easily control the flame on an alcy stove, the way that you can with canister stoves, so they're not ideal for cooking food where regulating heat output is important. However with thoughtful construction, ideal flame propagation can be achieved to boil water as quickly as possible. Other pros that come with using an alcy stove are: They're tiny, light weight (less than 1oz!), reliable and have a simple design. In fact, they're so simple in design that I made one myself. Special thanks to zenstove.net for the detailed instructions & tips!

The Theory:
The theory behind the side burning stove that I made is simple. The stove consists of an inner and outer fuel chamber that are connected by weep holes on the bottom of the inner chamber. When initially lit, the alcohol burns in the inner chamber. This action, essentially, pre-heats and primes the stove. The burning alcohol in the inner chamber heats the fuel in the outer chamber, vaporizing it and forcing it out the 24 jets drilled in the side of the can. The escaping vapors are then ignited. When a pot of water is placed on top of the stove the inner chamber is extinguished leaving the 24 jets to burn and heat the pot above.

The Construction:

The stove consists of these three pieces, from left to right: a bottom (20mm tall), the inner wall (40mm tall with a 47mm Ø and three fuel ports/weep holes) and a top (with 24 evenly spaced, .6mm Ø jets, placed 15mm from the top). For the top piece, Use a can-opener to lightly cut the bottom out of the can.


The bottom 20mm piece must slip over the 30mm top piece, sandwiching the inner chamber wall between the two. This requires some dilating (stretching) of the bottom piece. To do this, use an unopened can and force it into the bottom piece several times. It helps to polish the unopened can before doing this. After dilating the bottom piece, smear a light coating of J-B Weld along the inside of the bottom piece.



After the J-B Weld has set overnight, you can then polish the stove if you wish. I opted to polish mine by removing the paint with sandpaper and then shining it up with steel wool. I may even get some aluminum polish and put a nice shine on it, but I'm sure it's going to get beat up pretty good in my pack this summer.

4 comments:

Heber said...

Glad to see you venturing into the alcy stove world. I'll warn you that building stoves is a bit addictive! I got into a phase where I made one every few days to try and tweek the design. Luckily that's over now :)

The side-jet design isn't one I've used because I tend to favor narrower pots like Heine kegs.

I keep my alcy stoves for 3-season use. In the winter they don't work as well.

Have fun!

recumbent conspiracy theorist said...

Hi Mike,
I love these little stove projects you are doing. Each one has a bit of chemistry and physics to think about and light fabrication for fun.

I like the alcy burner. Superlight and no mess. And this from the stove zen site: Lacks Brand Name - North Face wearing, Mountain House eating, Starbucks drinking, Honda Element driving "outdoors people" will refer to you as "ghetto" and/or "trailer park"

-Hilarious!

Your last post reminded me of an article I read in QST (amateur radio journal) a few months ago about a ham who thru hiked the entire AT. He packed along a small QRP (low power) HF transmitter and made at least one Morse code contacts from each state.

Michael O'Hara said...

Thanks Heber:

Yeah, I've actually made three of these side burners so far. The first one was just slapped together with no instructions. It had leaks galore and just didn't work. The second one was better but I dented the top piece and it ended up cracking and leaking vapors really badly, creating non-uniform flames. The third and last one I made came out nearly perfect. There is a crack that I filled with JB Weld. I can see myself perfecting a final attempt though...

Michael O'Hara said...

RCT:

Yeah the Zen website is fantastic isn't it? Super detailed and informative and the author has a great sense of humor to boot!

Very cool about the guy checking in via radion on the AT!