Backcountry boiler:conelike alcohol efficiencyFromFancyFeas

Here's the place you can post your favorite wood burning stove and also information on how to build and where to get supplies.
bbb
Posts: 47
Joined: Thu Jun 09, 2011 7:27 am

Backcountry boiler:conelike alcohol efficiencyFromFancyFeas

Postby bbb » Tue Jul 24, 2012 10:04 am

I think a Backcountry Boiler (BCB) and Fancy Feast derived stove could perhaps approach Trail Designs Caldera cone like alcohol efficiency (15ml alcohol per 0.5 litre of water). The official BCB firefelt "burner"'s official figures are not quite as good as those of the cone.

But....
the inside of the BCB is a cone, it (unfortunately for alcohol) just has a chimney hole in the middle through which the alcohol heat races, leaving early perhaps having never contacted the BCB walls:

so block the early exit from the chimney with a stainless steel/ti foil tube so that gases are forced along the water holding walls just like in a TD cone.

One diagram shows a possible fancee feast style wick stove, the other shows my (shortlived) contraption for proving the idea might work: a closed aluminium tube attached to springy Stainless mesh which hangs from chimney.

I think by blocking the centre of the cone with the tube (as opposed to a damper on chimney top) the hot gases should be forced to swirl round the outside of the cone more, hopefully transferring more heat to the water.

In both cases the BCB base could be used or the boiler set on stones/other support (the latter seeming more stable and perhaps lighter when alcohol only use intended). (Tube height would need to vary accordingly).

BCBFFeastBurner.JPG
BCBFFeastBurner


BCBAsConeProverMYOG.JPG
MYOG idea

User avatar
zelph
Posts: 15783
Joined: Tue Aug 14, 2007 1:53 pm

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby zelph » Tue Jul 24, 2012 5:02 pm

Your ideas are viable. Good thinking.

The BCB needs holes all the way around the burner cup for even air distribution around the wood stack. Most important for the use of alcohol are the holes all the way around to get even distribution of flame against the walls.

Place a metal disc over the fancee feest stove to guide the flames to the wall. The disc should be 1/2" smaller in diameter of the taper wall of the BCB. I did that long ago and it works well.
http://www.woodgaz-stove.com/

bbb
Posts: 47
Joined: Thu Jun 09, 2011 7:27 am

Re: alcohol efficiency from damper

Postby bbb » Tue Sep 25, 2012 1:36 pm

So far one test of a simple damper and a doughnut open well burner formed from one pot inside a bigger one gave acceptable efficiency: 15-20ml for a boil.

The damper covered 50% or slightly more of the chimney.

BCBwithDamper.JPG
Damper and doughnut burner

User avatar
zelph
Posts: 15783
Joined: Tue Aug 14, 2007 1:53 pm

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby zelph » Wed Sep 26, 2012 1:24 am

I like the idea of using something as a damper to prevent runoff of the flames.

I think a Venom Super Stove wouold work well. It will hold 1 ounce of fuel suspended in the fiberglass to help govern the rate of burn.

Using a top damper on one of my kelly kettles really improved fuel efficiency when using wood. It should do the same for alcohol.

A carbon felt cone 1/2 inch smaller in diameter and the same height of the BCB to fit inside would be ideal. The flames would hug the walls for sure. Carbon felt is really light weight. The cone would sit on top of the alcohol burner.
http://www.woodgaz-stove.com/

english stu
Posts: 27
Joined: Mon Oct 15, 2007 3:51 pm

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby english stu » Sat Nov 10, 2012 12:03 pm

What diameter holes are suggested being added to the BCB fire pan and is stainless steel being suggest for the damper.I note there is small handle being added to the damper is that just a nut and bolt? The plate on top of a Fancy feast seems a better bet than a steel tube has anyone compared them.

User avatar
zelph
Posts: 15783
Joined: Tue Aug 14, 2007 1:53 pm

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby zelph » Sat Nov 10, 2012 5:30 pm

I suggest stainless steel or brass for the damper and 3/8" diameter holes. Lots of air at the base insures a good start. The damper can control the burn rate if you feel there is too much air coming in at the base.
http://www.woodgaz-stove.com/

bbb
Posts: 47
Joined: Thu Jun 09, 2011 7:27 am

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby bbb » Mon Nov 12, 2012 9:12 am

english stu wrote:What diameter holes are suggested being added to the BCB fire pan and is stainless steel being suggest for the damper.I note there is small handle being added to the damper is that just a nut and bolt?


I used 5mm holes, but I still prefer the bigger mesh base (for wood). I don't know whether extra holes in the supplied firebase are better for alcohol.

Yes, I used Ti foil for the damper so the bolt is to weight it down / secure it against being blown off sideways (and be a handle).

english stu
Posts: 27
Joined: Mon Oct 15, 2007 3:51 pm

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby english stu » Tue Nov 20, 2012 10:25 am

bbb ,Have you finalised a design for the larger fire basket that overcomes the flames up the side issue. I made the damper it works a treat.

bbb
Posts: 47
Joined: Thu Jun 09, 2011 7:27 am

Re: Backcountry boiler:conelike alcohol efficiencyFromFancyF

Postby bbb » Tue Nov 20, 2012 4:59 pm

english stu wrote:bbb ,Have you finalised a design for the larger fire basket that overcomes the flames up the side issue.


I get smoke rather than flames through the (narrow) gap in the foil/mesh firebase (but use a shortened boiler sleeve as a precaution which saves weight and avoids possible melting due to hot smoke): it has now blackened the lower half of the boiler a bit more but it doesn't come off on hands like soot does....
I would be nice to seal the gap though: one way would be to remove the lip from the standard base and use that lip to rest between the boiler and mesh base..... I am still thinking about whether to do that (I would then need to order a replacement base in order to have a "stock" firebase mode, but I don't like that mode as much so...)


english stu wrote:I made the damper it works a treat.

:D


Return to “WOOD BURNING STOVES”

Who is online

Users browsing this forum: No registered users and 10 guests