Stage 2: 'Wood-gas stove for developing countries'

[Elines]

In the thread 'Wood-gas stove for developing countries'
http://www.bushcraftuk.com/forum/showthread.php?t=84396&highlight=
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I asked if anyone had made a stove to the actual design in the paper:
http://www.waoline.com/science/newen...odGasStove.pdf

.The main schematic is:
http://bp2.blogger.com/_bt_33o-gQoY/R5ecRwomd-I/AAAAAAAAAxI/mQSMIz0YViY/s1600/stove.jpg
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No-one seemed to have done it so I thought I would have a go.
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(People skilled at metal work should be sitting down and away from sharp objects when reading the remainder.)
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The finished stove looked something like this:
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https://lh3.googleusercontent.com/-8Ni2B4TzeMs/TyMRWzCUGII/AAAAAAAAB8E/2q9nkqX42TY/s512/CIMG6664.JPG?gl=GB
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SUMMARY
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My impementation of the design did not work well but it has given me some ideas for another stove.
I set out here what I did in case it is of help to someone else with better ideas, skills and tools than me
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MATERIALS

Two large heinz tomato soup cans and a baked bean can
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PARTICULAR POINTS
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(1) the valve at the bottom was relatively simple to make and could be a useful feature in other stoves
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https://lh6.googleusercontent.com/--V9Vf0n4-Ok/TyMQ_Ve9X3I/AAAAAAAAB38/MKtMGNeB5Cw/s512/CIMG6653.JPG?gl=GB
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https://lh5.googleusercontent.com/-HQCRACkFHsw/TyMRA_haoCI/AAAAAAAAB4E/gZrYpX8x64U/s512/CIMG6654.JPG?gl=GB
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as it gives some control over air flow.
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(2) Because of the valve in the bottom you need a grate - I just used screwed up galvanised wire as it was all I had - worked well enough for my trial, but something like the grid off a disposable BBQ would probably be better
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https://lh6.googleusercontent.com/-2g7mrwyJIGs/TyMRbbR9bBI/AAAAAAAAB5k/uQtqdYCfRXg/s512/CIMG6666.JPG?gl=GB
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(3) I tried various ways of holding the 'gas wick' in place
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https://lh4.googleusercontent.com/-LgrMv6ueiuI/TyMRQRnLk5I/AAAAAAAAB8A/Y8pjnLSR11Y/s512/CIMG6661.JPG?gl=GB
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https://lh6.googleusercontent.com/-CTtJj5W5e4o/TyMRYhWsF4I/AAAAAAAAB5c/JapYLeGqVd0/s512/CIMG6665.JPG?gl=GB
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but in the end I just rested it on the bolts on the inside
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https://lh4.googleusercontent.com/-WMIqAiiTiIc/TyMRU9LZzZI/AAAAAAAAB5M/EN7DHY5xtUM/s512/CIMG6663.JPG?gl=GB
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https://lh6.googleusercontent.com/-l6zwh7_iPEo/TyMRsRBRD_I/AAAAAAAAB8Q/uzu952IeVIs/s512/CIMG6673.JPG?gl=GB
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(4) with the annular ring reduced to about 5mm the flame was a deep orange with occasional hints of blue, so the design seemed to be having some effect on the flame/efficiency of burn
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https://lh3.googleusercontent.com/-Jjy3NwowWfc/TyMRyUBOixI/AAAAAAAAB8o/ISAyHlaDaY8/s512/CIMG6679.JPG?gl=GB
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5) Insulating the unit (top and bottom halves) would probably have improved the gasification but as it was the bottom tin can was getting red hot
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https://lh4.googleusercontent.com/-IWj5W3oQTnU/TyMR0GagH1I/AAAAAAAAB80/WjGa-VzhdEs/s512/CIMG6682.JPG?gl=GB
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so if you want to have a go at this then it would be better to use a more robust lower unit
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(5) I read the design to require that you clip the upper part to the lower part after you have lit the fire. I didn't know how I might do that. Even better if you were to use a method that allowed you to easily adjust the gap. I had to make do with nuts and bolts and it was a faff to amend/correct things eg when I forgot to put the grate in and again when I changed the annular gap
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(6) You put the fuel in and then light the fire from the top
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https://lh6.googleusercontent.com/-OokUMFMuNbE/TyMRmhHglSI/AAAAAAAAB6E/k_2NqwiGp60/s512/CIMG6670.JPG?gl=GB
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I added a bit of tinder and used a fire lighter to get it going
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(7) The unit should have legs. These weren't essential for my tests but if you have a go then I think you should have only three legs , suitably positioned so that you can still open and close the valve fully
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(8) You need some way of providing a pot rest that allows a gap for the flames to appear at the top - not essential for my test
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NEXT TIME
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Well ... as regards this design there won't be a next time for me. When I get the urge I might have a go at a stove which is just this:
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https://lh5.googleusercontent.com/-nyXS9q4W96A/TyMRDJYpX7I/AAAAAAAAB70/flPKBBoa9qk/s512/CIMG6655.JPG?gl=GB
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or something like it

And if anyone ever does make a stove to the original design I'd be more than interested to hear how it worked

[Teepee]

I must have missed your first post.

I've made a few of 'em over the last 3 years, fascinating things that they are. Most of mine use a fan though to get some power out of them, clean the burn and reduce the size.

I put a thread up on BCUK here


http://www.youtube.com/watch?v=nQJjZsFflQY
(http://www.bushcraftuk.com/forum/showthread.php?t=57851)
Pics of a few;
They all work in the same way, but use twin walls. The one in the middle is more powerful than my petrol Primus(without the useless gas wick in the pic), the one on the right will boil 9 litres on a load of fuel(baked bean tin). The 3rd in ishows a tlud, battery pack, meths burner,forge, windshield and bag of fuel. All are stainless/aluminium apart from the polkadot tin which is next to useless.

853285378536853385348538853085 318535

[udamiano]

Nice one guys, very interest thread.

Great prototype Chris goodjob

Nice design phil. will love to see one in action in the flesh, so to speak

[Elines]

Soem good stuff there - I think twin walls is the way to go

[Teepee]

Nice one guys, very interest thread.

Great prototype Chris goodjob

Nice design phil. will love to see one in action in the flesh, so to speak

I'll bring my stash of em to Rough Close next time I'm over


Soem good stuff there - I think twin walls is the way to go

It has to be a twin wall with a fan, for a natural draught stove its debatable how much benefit there is to further preheating the incoming air. I do tend to agree though and always favour the twin wall.

[ged]

... I've made a few of 'em over the last 3 years, fascinating things that they are. Most of mine use a fan ...

The flames in some of those photos look very impressive. Clearly a fan makes a huge difference to the efficiency, so I guess it's all about getting enough air moving fast enough.

Chris, I think you need to make your stoves taller to get a bigger chimney effect.

The manual for my wood burning stove says it needs a minimum of about four metres... :yikes:

[Elines]

.........

Chris, I think you need to make your stoves taller to get a bigger chimney effect.

The manual for my wood burning stove says it needs a minimum of about four metres... :yikes:

mmm ..... I used what materials I had available but they weren't too far from the original spec by the researchers, so there must be a reason why they got it to work (and I didn't) without a 4m chimney. The design is for developing countries and so had to be relatively cheap and easy to make (which is why I wanted to have a go at it).

So until someone has another go - or better still - find somebody who has already made it (I couldn't find anybody) then the jury will have to stay out on the validity of the design

I'm satisfied that even if I got 'proper' materials then I would be unlikley to get a significant;y better result