TLUD - Top Lighting Up Draft Quotes

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zelph
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TLUD - Top Lighting Up Draft Quotes

Postby zelph » Wed Sep 08, 2010 1:03 pm

I had linked many times to HammockForums.net to give direction on good conversations and information pertaining to TLUD stoves. Now all of those links are deadended because of many of the Non-Hammock forums being locked off accept to "Donating Members" only. This is an example of what you get when I link to the thread now:
http://www.hammockforums.net/forum/show ... hp?t=12425

If you Google TLUD stove and find a link to Hammockforums none of the links will connect unless you are a "Donating Member".....just for your information.

So I quote from page one of the thread on through page 20:

(Quote)

Albert Skye 12-05-2009 13:13
TLUD stoves

I'm wondering if anyone has personal experience with both single- and double-wall TLUD stoves (constructed/used appropriately, of course: low primary:secondary air ratio, small pieces, batch-loaded and packed with uniform density).

My primary interest is in reducing smoke and I'm wondering if the outer wall makes a significant difference (as I aim to also reduce weight/volume). I can make my own experiments but I imagine some of you have already done so. Pedro? Anyone? :)

pedro 12-05-2009 14:04
There's a lot of folks on here with personal experience with TLUD stoves, although they might not call them that. Virtually all of the wood gasifying camping stoves are TLUDs. My personal experience has been that the outer wall is unnecessary, the same job gets done by a close fitting windscreen. When I light my stove, and it starts gasifying, the secondary flames will actually shoot outward from the inside of the can, until I put the windscreen (made from turkey baster pan) around it. Then, the secondary combustion air is funneled up the "chimney" that is formed by the windscreen, and gets sucked into the secondary burner holes, and I get the same sort of wood gas fire that we all (well, some of us) know and love. If you look at Garlington's site, and the Penny Wood Stove site, they both came to the same conclusion. The outer jacket would have a much bigger effect if the stove were taller, because the draft generated in a taller stack would be much more powerful, but from the tinkering I have done, I don't find much of a difference on these shorty stoves. Actually, if you use a windscreen that surrounds your pot as high as possible, the draft will be significantly enhanced, like the Kelly Kettle effect.

Redoleary 12-05-2009 14:29
I have found basically the same to be true, where the scale of the stove is as small as a pint can it makes almost no difference wheather its single or double wall. I recently made a "convertable" stove that I could easily remove the outer wall while it's burning and it does make a difference to the flame pattern, but not really to the intensity. I am hoping to make a video of the thing in action, but I've never published anhthing to youtube so that may slow me down a bit, with some luck that may happen tonight.

Redoleary 12-05-2009 22:15
Well here are the videos, skip right to #2 if you just want to see something on fire. They lack the entertainment value that Shug's videos have but what do you want for my first try at video? Hope its insightful.
Good luck,
RED
http://www.youtube.com/watch?v=u_2CI6gnUco
http://www.youtube.com/watch?v=L6jpoI5gMSU

Sailor 12-05-2009 22:28
I believe the reason for the double wall is to make a chimney for the secondary air which both increase draw and increases temperature of that air. In forced air stoves, the enclosed area obviously allows the fan to push air at high velocity to the secondary air vents. For stoves without fans, I would not think the outer wall would make much difference. Heating of the air in the short distances of the little tin can stoves is minimal, I believe, so in sum, single wall prbly isn't much less effective/efficient. However, the taller the stove, the better the draw of secondary air and therefore, the more important is the outer wall. At least that's what I think I figured out.

Albert Skye 12-05-2009 23:14
Thanks for all your comments. :)

Garlington and Jurey seem trustworthy to me but it is good to have more input.

Quote:
Originally Posted by pedro (Post 177932)
[...] wood gasifying camping stoves are TLUDs.
I avoided the usual vernacular because these stoves seem to be significantly misunderstood/misused (i.e., I'm looking for feedback from those like yourself who understand how they work and how to use them).

Quote:
Originally Posted by Redoleary (Post 177941)
I recently made a "convertable" stove [...]
Thanks for those videos. I'll burn something soon! ;)

pedro 12-05-2009 23:35
Quote:
Originally Posted by Albert Skye (Post 178105)



I avoided the usual vernacular because these stoves seem to be significantly misunderstood/misused (i.e., I'm looking for feedback from those like yourself who understand how they work and how to use them.

I agree, there is a lot of misunderstanding about how these stoves work. When I first got interested in them, I read the Reed/Lawson paper on their research, which was very interesting, but they were using the term "inverted downdraft gasification" to describe what they were doing. With all due respect to these men and their stellar work, that is a cutesy and confusing way to describe it. Too cute by half. Once I learned about downdraft gasifiers, I got the reference, but as someone approaching the subject for the first time, it was infuriating and a roadblock to understanding. Apparently, I'm not alone, as I have seen posts on the net from people who claimed to see a downdraft occuring in their TLUD stoves! And other nonsense...(end of rant)

pedro 12-05-2009 23:48
Good videos, Red!

Albert Skye 12-05-2009 23:49
Quote:
Originally Posted by pedro (Post 178107)
[...] downdraft [...]
Fear not, Zelph is on a crusade to cure anyone of that misconception. ;)

By the way, have you made a real downdraft gasifier? I'm also curious about using the technology in applications that are not so restricted by weight and size.

Redoleary 12-06-2009 07:02
While not the easiest site to navigate, there is a lot of good info here and the stoves are not restricted by weight or size: http://www.bioenergylists.org/
I think a lot of efficiency comes from having a taller stove so the gases all have time to do their thing, and an insulated burn chamber and chimney go a long way in keeping them hot, the problem with all that is that it translates poorly into a small backpackable package.
Thanks for the nice feed back on the videos.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:05 pm

Hawk-eye 12-06-2009 07:23
Quote:
Originally Posted by Redoleary (Post 178131)
.... Thanks for the nice feed back on the videos.
Thanks for posting those videos of yours ... found them interesting to watch. Especially the comparison video of the burn pattern.

Good info!

pedro 12-06-2009 08:43
Quote:

By the way, have you made a real downdraft gasifier? I'm also curious about using the technology in applications that are not so restricted by weight and size.
No, I haven't tried that yet. It would be fun to try running a generator off of one.

Agfadoc 12-06-2009 10:44
Great videos Red, thanks for sharing!

koaloha05 12-06-2009 11:44
Just an observation.

2 Attachment(s)
On the BushBuddy I use it looks more to be an updraft. Not downdraft. I found that by having the intake vents (bottom holes in the outer skin) unobstructed by a windscreen I get a cleaner and what seems to be a hotter burn. The cooler ambient air being sucked in and rising as heated exits the inner holes at the top of the inner skin seems to be ignited by the hot fire inside the BB resulting in a hotter cleaner burn than just a fire in a can. Having the windscreen higher around the pot and protecting the fire above the top of the flame results in a significant improvement in heating efficiency under any condition. Photo enclosed.

An interesting comparison would be a single wall with bottom vent holes vs. the BB double wall. Weigh out some as identical as possible wood fuel and monitor the temperature heating profile of a set volume of water under identical conditions.

jaygnar 12-06-2009 12:13
Quote:
Originally Posted by koaloha05 (Post 178242)
On the BushBuddy I use it looks more to be an updraft. Not downdraft.

Yeah, that's what people mean about the stupid use of complex terminology.
Inverted downdraft = Updraft
Whoever came up with "inverted downdraft" should be pushed down a rubber flight of stairs and spanked soundly for good measure.:D
It's almost like the people were trying to confuse others on purpose.
I too was confused early on by the silly wordsmithery!!

Redoleary 12-06-2009 12:19
Quote:
Originally Posted by koaloha05 (Post 178242)
An interesting comparison would be a single wall with bottom vent holes vs. the BB double wall. Weigh out some as identical as possible wood fuel and monitor the temperature heating profile of a set volume of water under identical conditions.
I've done some test similar to this, where I've purchased a bag hickory wood chips for a smoker for my fuel source, figuring thats the best I can do to simulate a consistent fuel, and I've weighed the wood chips and put the same in each stove, as well as just filled each with as much as they would hold. On the one hand you would be measuring the stoves ability to extract the greatest amount of heat from the same weight of wood, on the other hand its more a measure of how you would actually use it, which is probably going to be as full as you can make it before light off. In all cases I use the same amount of H2O and the same pot. I tend to favor the short/large diameter pots and I usually test with 1L H2O, because I most often camp with my wife and we usually boil a lot of water.
As I recall from these tests the results were always very similar, where there was no walk away winner. However, I think recall comparing a single wall pint can stove vs. double wall pint can stove with a veg. can for the inside of the double wall, where the double wall would not have the same capacity for holding wood as the single and the single ran out of wood first. Does that mean it burns hotter or just faster, and how much is lost to the stove itself? The single wall gets red hot sometimes and I can only imagine that the double wall must enjoy some small amount of insulation or at least some small degree of preheat for the secondary air?? All good things to wonder about I guess, as I sure don't know the answer?

Thanks again for watching the videos.

Good Luck
RED

Albert Skye 12-14-2009 15:32
Nat Mulcahy - World Stove

Nat and his stove designs seem to be ahead of the pack. They aren't TLUD; he calls it coaxial gasification. They can operate in full gasification mode (leaving only a small amount ash), or in pyrolytic mode (leaving unburned charcoal, no ash). They operate in many different configurations, with forced air or natural draft, and fuel can be added as needed (not batch loaded).

In pyrolytic mode, his design does indeed suck gas (by venturi) from the bottom ports and mix it in the plenum before exiting the upper ports and igniting a flame cap (which prevents oxygen from entering through the top).

He even makes a beautiful little backpacking stove called the Beaner (which could likely be made lighter). It appears that a double wall can be useful, even on a small scale.

- World Stove website
- videos
- DIY tin stove

Frawg 12-14-2009 15:38
Quote:
Originally Posted by jaygnar (Post 178249)
Yeah, that's what people mean about the stupid use of complex terminology.
Inverted downdraft = Updraft
Whoever came up with "inverted downdraft" should be pushed down a rubber flight of stairs and spanked soundly for good measure.:D
It's almost like the people were trying to confuse others on purpose.
I too was confused early on by the silly wordsmithery!!
I believe it was coined by Ray Garlington, in deference to and comparison with the "downdraft gasifier" that <name forgotten> published for use in the developing world. If you were familiar with the downdraft gasifier, Ray's adaptation of the name told you instantly what his stove was about. :D My memory may be a bit hazy, though.

Albert Skye 12-14-2009 16:41
Quote:
Originally Posted by Frawg (Post 181631)
I believe it was coined by Ray Garlington, in deference to and comparison with the "downdraft gasifier" that <name forgotten> published for use in the developing world. If you were familiar with the downdraft gasifier, Ray's adaptation of the name told you instantly what his stove was about. :D My memory may be a bit hazy, though.
As it reads on Ray's own site:

Quote:
In May, 1996 T.B. Reed and Ronal Larson of the Biomass Energy Foundation in Golden, Colorado presented a paper titled "A WOOD-GAS STOVE FOR DEVELOPING COUNTRIES" at the “Developments in Thermochemical Biomass Conversion” Conference, in Banff, Canada. In this paper they describe a wood stove which uses a component they describe as the “inverted downdraft gasifier, which operated using only natural convection.

pedro 12-14-2009 19:30
Quote:
Originally Posted by Frawg (Post 181631)
I believe it was coined by Ray Garlington, in deference to and comparison with the "downdraft gasifier" that <name forgotten> published for use in the developing world. If you were familiar with the downdraft gasifier, Ray's adaptation of the name told you instantly what his stove was about. :D My memory may be a bit hazy, though.
Actually, downdraft gasifiers were first used during World War II in occupied Europe. Gasoline was in very short supply, and downdraft wood gasifiers were attached to automobiles so that they could run on wood gas. They were very funky and clunky looking, but they worked very well. IIRC, the inventor's name was Imbert.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:06 pm

Frawg 12-14-2009 19:48
Thanks for the info, Pedro. Gotta look that up and learn more. I was familiar only with the (comparatively) recent incarnation that Ray adapted. :)

Edit: Found a cool document -- Wood Gas as Engine Fuel

Sailor 12-14-2009 22:16
Quote:
Originally Posted by Albert Skye (Post 181629)
Nat and his stove designs seem to be ahead of the pack. They aren't TLUD; he calls it coaxial gasification. They can operate in full gasification mode (leaving only a small amount ash), or in pyrolytic mode (leaving unburned charcoal, no ash). They operate in many different configurations, with forced air or natural draft, and fuel can be added as needed (not batch loaded).

In pyrolytic mode, his design does indeed suck gas (by venturi) from the bottom ports and mix it in the plenum before exiting the upper ports and igniting a flame cap (which prevents oxygen from entering through the top).

He even makes a beautiful little backpacking stove called the Beaner (which could likely be made lighter). It appears that a double wall can be useful, even on a small scale.

- World Stove website
- videos
- DIY tin stove
I've tried contacting him a couple times without success, and wondered how good that little BEANER works without forced air. The heat/cleanliness of Reed's woodstove is way way above the tin can's without forced air, and Nat's videos look a little too good to be true--but I'm quite interested.

I think much work still needs be done on improving air flow by can shape...

Shug 12-14-2009 22:17
Liked the videos Red ..... love a good burn.
Shug

pedro 12-14-2009 22:59
Quote:
Originally Posted by Sailor (Post 181810)
I've tried contacting him a couple times without success, and wondered how good that little BEANER works without forced air. The heat/cleanliness of Reed's woodstove is way way above the tin can's without forced air, and Nat's videos look a little too good to be true--but I'm quite interested.

I think much work still needs be done on improving air flow by can shape...
I've been interested in the beaner for sometime, and have had several discussions with worldstove's US sales rep concerning them. They have had some trouble getting production going, and the arrival of the first batch of stoves to the US kept getting pushed back. The last thing I heard, I could buy one, but I'd have to buy it from Italy. I am not prepared to do that.

Sailor 12-15-2009 00:21
Quote:
Originally Posted by pedro (Post 181828)
I've been interested in the beaner for sometime, and have had several discussions with worldstove's US sales rep concerning them. They have had some trouble getting production going, and the arrival of the first batch of stoves to the US kept getting pushed back. The last thing I heard, I could buy one, but I'd have to buy it from Italy. I am not prepared to do that.
I agree about buying from Italy--shipping more than product--but what's so hard about production for the simplest of their designs, when the more complicated, the the WorldStove, are intended for 3rd world production. And the vids of the WorldStove burning-- a very blue flame.... maybe something a little fishy?

Albert Skye 12-15-2009 00:37
Quote:
Originally Posted by Sailor (Post 181840)
And the vids of the WorldStove burning-- a very blue flame.... maybe something a little fishy?
I think the combination of perfect pellets, forced air, and filtering through the charcoal has something to do with that, not to mention that Nat just seems like a smart person who understands the physics involved.

In any case, as you mention, they're not hard to make. I intend to make one following these plans.

As for single-walled TLUDs, after a few experiments with tin cans, I'm questioning the utility of secondary air holes because I get a clean flame rising off the lip with only primary air holes in the bottom.

Sailor 12-15-2009 00:59
I'd forgotten both about those plans and my intention to follow them...2nd thing I'd forgotten.

His swirl air pattern seems central to things. The secondary air holes sure aren't needed with a Kelly Kettle, but that chimney gets a great velocity, which I'd like to replicate with secondary air. I'm sure the KK's exhausting plenty of unburned gas, which is what secondary air holes are intended to burn. My quest is a air velocity like the KK, no forced air, and secondary burn that Reed gets with forced air. Then I'd have something.

Redoleary 12-15-2009 05:01
Quote:
Originally Posted by Shug (Post 181811)
Liked the videos Red ..... love a good burn.
Shug
Thanks Shug.

Regarding plans: Is he getting secondary air from the difference in height between the to cans? No need for a fire grate to hold it up off the bottom? Could that be part of my problem (among many other things I'm sure:D) that I'm getting too much air in and cooling the flame, as mine never burn blue?

With the garlington stove I noticed that there doesn't seem to be a need to seal the top of the stove between the inner and outer walls? That could open up a new line of thinking for me. :)

Albert Skye 12-15-2009 14:32
Quote:
Originally Posted by Redoleary (Post 181861)
Is he getting secondary air from the difference in height between the to cans?
As I understand it, Nat's stoves are designed to work in pyrolytic mode (i.e., there is no primary air; the fuel is converted to charcoal without oxygen). The pressure differential causes air (and wood gas) to be sucked out of the bottom ports and replaced by heated nitrogen drawn from the flame cap (which consumes any oxygen which might otherwise enter the fuel chamber).

In my own experiments (with single-walled TLUDs), I deliberately made primary air ports only in the bottom which enables me to adjust the air flow by elevation (i.e., it can be cut off completely or wide open). Too much primary air causes the flame to separate from the can; not enough and it withers.

Frawg 12-15-2009 15:27
Quote:
Originally Posted by Albert Skye (Post 181664)
As it reads on Ray's own site:
Thanks for the clarification. Guess my memory is truly swiss cheese, and I will cease and desist henceforth. IAE, the point of my original comment was to cover Ray's backside -- not that it was needed.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:08 pm

oldgringo 12-15-2009 15:31
Quote:
Originally Posted by Frawg (Post 182055)
...Guess my memory is truly swiss cheese...
You're not alone...:(

Frawg 12-15-2009 15:44
Quote:
Originally Posted by oldgringo (Post 182057)
You're not alone...:(
Ah well, at some point we won't care. :laugh: 'Til then I'll just lurk and try to absorb what little I can from the stoichiometrists. ;)

Agfadoc 12-15-2009 16:10
Love that beanie, to me it looks like a large and small water bottle with holes properly placed in it. Would love to have the real equipment to make something like that, it would be very easy to crank out dozens.

pedro 12-15-2009 16:47
Quote:
Originally Posted by Sailor (Post 181840)
I agree about buying from Italy--shipping more than product--but what's so hard about production for the simplest of their designs, when the more complicated, the the WorldStove, are intended for 3rd world production. And the vids of the WorldStove burning-- a very blue flame.... maybe something a little fishy?
He doesn't intend for the burner or the bottom pan on the worldstove to be produced in 3rd world countries. The burner in particular is a highly enginneered, heavily machined part. The idea is for his company to make those parts and ship them to 3rd world countries, where the simple stuff like jackets and spacer rods can be manufactured and assembled with his parts. I agree about the blue flame; it looks to me like he has shot some of his video with the white balance so out of whack that it makes the flames look more blue than they are. Take a look at his videos again, but pay attention to the background. Everything is pretty blue, isn't it?

BTW, I talked to Matt the US sales rep at Worldstove today, and he says that they have about 50 of the Beaners in the US now. If everything works out, I'm buying one.

Quote:
Originally Posted by Albert Skye (Post 181841)
I think the combination of perfect pellets, forced air, and filtering through the charcoal has something to do with that, not to mention that Nat just seems like a smart person who understands the physics involved.

In any case, as you mention, they're not hard to make. I intend to make one following these plans.
As for single-walled TLUDs, after a few experiments with tin cans, I'm questioning the utility of secondary air holes because I get a clean flame rising off the lip with only primary air holes in the bottom.

The everythingnice stove is not the same design as the stoves he makes.
As he states on his site, it is just a good TLUD design that he ran across while doing his research. It looks to me to be pretty much exactly the same as the Peko-Pe stove. Google that and you should find an interesting story.


Quote:
Originally Posted by Sailor (Post 181844)
I'd forgotten both about those plans and my intention to follow them...2nd thing I'd forgotten.

His swirl air pattern seems central to things. The secondary air holes sure aren't needed with a Kelly Kettle, but that chimney gets a great velocity, which I'd like to replicate with secondary air. I'm sure the KK's exhausting plenty of unburned gas, which is what secondary air holes are intended to burn. My quest is a air velocity like the KK, no forced air, and secondary burn that Reed gets with forced air. Then I'd have something.

I'm messing around with the idea of making the windscreen go all the way up to the top of the pot, and entirely surrounding stove and pot, not just a winscreen but a chimney really. This is what the outer can does normally; suck in air down low, and duct it to the secondary burners. The heat imparted to the air as it passes by the inner can helps to induce draft, which increases air flow. The problem with these short stoves is that there isn't enough chimney height to really get a draft going strong. If the chimney/windscreen is twice as tall, there is much more draft, and more air will get sucked into the secondary burn holes. In addition, the flames will get ducted towards the pot. It's the same effect as the KK, maximizing surface area exposed to flame. I'm just using the outside wall of the pot instead of the inside. There may also be possibilities of using this same setup to bake. Hopefully I will be able to post some video soon from the lab. (Cue sound of thunder and maniacal laughter)


Quote:
Originally Posted by Redoleary (Post 181861)
Thanks Shug.

Regarding plans: Is he getting secondary air from the difference in height between the to cans? No need for a fire grate to hold it up off the bottom? Could that be part of my problem (among many other things I'm sure:D) that I'm getting too much air in and cooling the flame, as mine never burn blue?

With the garlington stove I noticed that there doesn't seem to be a need to seal the top of the stove between the inner and outer walls? That could open up a new line of thinking for me. :)

In those plans he is in fact getting his secondary air from the height difference. On the Garlington stove the outer wall isn't really a wall, just a windscreen. It's a single wall stove.

Agfadoc 12-15-2009 21:04
I am trying to make my little thermos stove like the everythingnice stove, but using jets at the top instead of just the spacing between the two cans at the top.

I have never seen one of these burn in person, but I am curious on how well the fire stays lit as there is really not much air to keep it combustible. I am sure it works, but I'll take the plunge and see how it goes. Thanks for all the links guys.

Sailor 12-15-2009 22:40
Quote:
Originally Posted by pedro (Post 182090)
He doesn't intend for the burner or the bottom pan on the worldstove to be produced in 3rd world countries. The burner in particular is a highly enginneered, heavily machined part. The idea is for his company to make those parts and ship them to 3rd world countries, where the simple stuff like jackets and spacer rods can be manufactured and assembled with his parts. I agree about the blue flame; it looks to me like he has shot some of his video with the white balance so out of whack that it makes the flames look more blue than they are. Take a look at his videos again, but pay attention to the background. Everything is pretty blue, isn't it?

BTW, I talked to Matt the US sales rep at Worldstove today, and he says that they have about 50 of the Beaners in the US now. If everything works out, I'm buying one.
Good points on production and photography. I'd like to get a Beaner too.

Quote:
Originally Posted by pedro (Post 182090)
I'm messing around with the idea of making the windscreen go all the way up to the top of the pot, and entirely surrounding stove and pot, not just a winscreen but a chimney really.
I think the shape of the chimney is part of the success of the KK--irregular, abrupt, etc changes slow air flow; slowly decreasing diameter of the chim. speeds it up. Love to see what you come up with.

Albert Skye 12-15-2009 23:31
Quote:
Originally Posted by Frawg (Post 182055)
Thanks for the clarification. Guess my memory is truly swiss cheese, and I will cease and desist henceforth. IAE, the point of my original comment was to cover Ray's backside -- not that it was needed.
No worries, you're not the only one to think it was Ray. My respect to Zelph for his excellent alcohol stoves but I think he might need some cover in regard to various comments about wood gasification. ;) My memory sucks too (that's why I bring in all the links); I prefer to use my brain for more important things like appreciating beautiful sunsets, good company and fine beer. :)

Quote:
Originally Posted by pedro (Post 182090)
The everythingnice stove is not the same design as the stoves he makes. As he states on his site, it is just a good TLUD design that he ran across while doing his research. It looks to me to be pretty much exactly the same as the Peko-Pe stove. Google that and you should find an interesting story.
All I found is a brief mention that it is his design and it does produce char, which leads me to believe that it also operates in pyrolytic mode as he claims for the Beaner, &c. It certainly is different from the Peko-Pe as seen in this document (I especially enjoyed the first paragraph); there are holes all over the inner cylinder. If Nat's stoves were operating in the same way as these TLUD designs, then I would expect to see holes in different places. I guess we'll find out soon enough; get that Beaner mate! :)

Quote:
Originally Posted by Agfadoc (Post 182159)
I am trying to make my little thermos stove like the everythingnice stove, but using jets at the top instead of just the spacing between the two cans at the top.
Good stuff! :) I've also been hunting for a thermos but I'm after the long narrow ones for some Beaner clone experiments; they seem to be about 51 mm (2") ID, just like the Beaner.

pedro 12-16-2009 06:31
All I found is a brief mention that it is his design and it does produce char, which leads me to believe that it also operates in pyrolytic mode as he claims for the Beaner, &c. It certainly is different from the Peko-Pe as seen in this document (I especially enjoyed the first paragraph); there are holes all over the inner cylinder. If Nat's stoves were operating in the same way as these TLUD designs, then I would expect to see holes in different places. I guess we'll find out soon enough; get that Beaner mate! :)

Right you are. My bad, I was very much mistaken.

Agfadoc 12-16-2009 11:22
I need your advice, it looks as if the Everything nice stove inner container does not have holes at the very bottom for the ash to drop out, hence the pyrolytic mode I assume creating biochar, but the Peko Pe seems to have one, I assume for gasification.

is this correct and do I understand this correctly.

If I wanted the least amount of soot on my pot and stove I am assuming that I want the pyrolytic mode as it burns the gases not the matter.

If I enclose the bottom of my thermos stove for pyrolytic use, will all I need is to not open the bottom of the inner can besides the porting holes on the side like the document Everythingnice stove has? Will twigs be enough without the use of pellets?

Has anyone here created a pyrolytic stove?

Albert Skye 12-16-2009 13:15
Quote:
Originally Posted by Agfadoc (Post 182307)
I need your advice, [...]
I think you've got it. You can always add more holes to your inner cylinder if it doesn't work out (convert it into a Peko Pe). It ought to work fine with any dry biomass that works in a TLUD.

I'm wondering if your thermos may be too short, and I think the upper holes may not provide enough draw (the pressure differential is critical). It seems you're implying that your inner cylinder has an opening in the bottom; if so, I think it needs to be sealed air-tight to work pyrolytically.

Anyway, fire it up and see how it burns! :) I didn't make one yet.
http://www.woodgaz-stove.com/

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zelph
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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:09 pm

Agfadoc 12-16-2009 17:55
The inner can does not have an opening on the bottom and the holes are exactly as the directions state, d + 1/2 O. the only significant difference is that I am using the holes at the top vs the continuous opening at the top between cans.

I have to run up and get some JB Weld or heat sealer to seal the two cans back together so I get as much flow out of the top holes as possible.

Thanks for your help.. Just wanted to be sure before I lock it down.

Sailor 12-16-2009 18:23
Check out Reed's woodgas stove. He does use forced air, but otherwise, I think the operating principles are the same. Smallish holes around the outside of the combustion chamber for primary air. Size and number of holes determines amount of air. Holes around the top for secondary air. When operating his, you fill, light at the top, and burn down. Pyrolytic burn most of the time, till all the volatiles are gone, then bbq time. Gotta have some 02, or no fire/ not heat, releasing the volatiles. Different stages of combustion. His woodgas stove is quite something--just wish a little lighter for hiking.

Agfadoc 12-16-2009 19:01
Those are one of the reasons I wanted to start building these stoves..

I happened to have an intel cpu fan and heatsink that fits perfectly into the bottom of the stove, so.. it may be part of my testing to see the improvement.

Sailor 12-16-2009 20:56
I made an aluminum gasket and have run the Woodgas stove with the KK setting on top. It so impressive, I may get arrested. I can make enough hot water that campers can take hot baths.

Big D 12-16-2009 21:42
How can I get in touch with Mat concerning the Beaner?

Sailor 12-16-2009 23:14
Start with www.worldstove.com

Albert Skye 12-17-2009 01:07
Quote:
Originally Posted by Sailor (Post 182473)
[...] I think the operating principles are the same.
All of the TLUD designs I've seen introduce some small amount of primary air (oxygen) into the fuel chamber. By contrast, Nat's designs are tuned to utilise pressure differential and maintain an absence of oxygen in the fuel chamber by sucking air (and gas) from the bottom ports. The vacuum in the fuel chamber draws air through the flame cap which consumes any oxygen and passes mostly superheated nitrogen which heats the fuel and releases gas. That is the difference as I understand it but I have yet to witness it in person.

The term pyrolysis is somewhat messy because sometimes it is used to mean decomposition by heat strictly in the absence of oxygen, and contrasted with thermolysis (simply decomposition by heat). Most TLUDs are burning in an oxygen-limited environment, limited enough to produce char, but they are not pyrolytic in the strict sense of the term, which it appears Nat claims his stoves to be.

pedro 12-17-2009 07:04
Quote:
Originally Posted by Albert Skye (Post 182567)
By contrast, Nat's designs are tuned to utilise pressure differential and maintain an absence of oxygen in the fuel chamber by sucking air (and gas) from the bottom ports. The vacuum in the fuel chamber draws air through the flame cap which consumes any oxygen and passes mostly superheated nitrogen which heats the fuel and releases gas. That is the difference as I understand it but I have yet to witness it in person.

Ever since I first saw Nat's stoves, I've been having difficulty figuring out how these are not simply T-LUD stoves that are made with highly efficient porting and airflow. Could you point me to a link where he describes this superheated nitrogen process and how he is pulling a vacuum in the fuel chamber? :confused:

Agfadoc 12-17-2009 07:44
I am going to try this test that should be the everythingnice stove, slightly modified with ports at the top, which as I understand it should leave remains of biochar in the bottom

http://www.hammockforums.net/gallery...0245_thumb.jpg

I am going to run up and get some pellets to be as close as possible to what is shown on video, if it works, I'll let you know..

Big D 12-17-2009 08:39
You guys are considerably more knowledgeable about the science of these stoves. I have rePly enjoyed reading and rereading these posts and links.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:11 pm

oldgringo 12-17-2009 08:57
Quote:
Originally Posted by Big D (Post 182651)
You guys are considerably more knowledgeable about the science of these stoves. I have rePly enjoyed reading and rereading these posts and links.
Ditto. Cool beans!

Gailainne 12-17-2009 09:33
Quote:
Originally Posted by Agfadoc (Post 182624)
I am going to try this test that should be the everythingnice stove, slightly modified with ports at the top, which as I understand it should leave remains of biochar in the bottom

http://www.hammockforums.net/gallery...0245_thumb.jpg

I am going to run up and get some pellets to be as close as possible to what is shown on video, if it works, I'll let you know..
Thats very similar to the one I made a couple of years back, I started with a Garlington design, but couldn't get water to the boil with it.

http://i161.photobucket.com/albums/t...CIMG0046-1.jpg

http://i161.photobucket.com/albums/t...CIMG0048-1.jpg

Here's the link to the blog I made of my attempts.

It was about then I got interested in alcohol stoves, so have never went back to it, I have a sheet of titanium, that will get used to make a lightweight one at some point.

Cheers

Stephen

Sailor 12-17-2009 11:08
Regards the pellets AD-- it seems to me that when we fool around with these stoves, checking how well they boil, burn and backfire, a fair test is to burn a common fuel for testing, and that being pellets.

Albert Skye 12-17-2009 14:19
Quote:
Originally Posted by pedro (Post 182608)
Could you point me to a link where he describes this superheated nitrogen process and how he is pulling a vacuum in the fuel chamber? :confused:
He talks about these details in several of his videos (sorry I don't recall exactly which ones) and here's a post from the mailing list (view as source to wrap the lines).

He stresses how the flame is capping the top opening. Gas is drawn from the lower ports by venturi. Naturally, this creates a vacuum in the fuel chamber and the only place for more air to enter is through the oxygen-consuming flame cap.

pedro 12-17-2009 15:46
Quote:
Originally Posted by Sailor (Post 182700)
Regards the pellets AD-- it seems to me that when we fool around with these stoves, checking how well they boil, burn and backfire, a fair test is to burn a common fuel for testing, and that being pellets.

I agree. How about weighing the fuel, or using a volumetric measure, before the burn?
How about timing the burn, from lighting up to end of flame? Thoughts?


Quote:
Originally Posted by Albert Skye (Post 182777)
He talks about these details in several of his videos (sorry I don't recall exactly which ones) and here's a post from the mailing list (view as source to wrap the lines).

He stresses how the flame is capping the top opening. Gas is drawn from the lower ports by venturi. Naturally, this creates a vacuum in the fuel chamber and the only place for more air to enter is through the oxygen-consuming flame cap.
I agree that you can create a vacuum using a venturi, if the nozzle is pointed in the right direction. I also understand the whole concept of not leaving any voids in the flame pattern, and how this is advantageous. What I don't understand is how this stove is not a T-LUD manufactured to extremely high standards. There is no question in my mind that Nat's engineering expertise is excellent. But just look at his burner! It's like a turbine. I'm just wondering if the jump in efficiency is due to superior porting technology.

Albert Skye 12-17-2009 16:17
Quote:
Originally Posted by pedro (Post 182811)
What I don't understand is how this stove is not a T-LUD manufactured to extremely high standards.
Ah, I see; sorry for the confusion. Nat calls it "coaxial gasification" in contrast to stratified gasification which is employed in a TLUD. As I understand it, it's coaxial because the hot nitrogen drawn from (through) the flame cap travels down the walls (not the middle) of the fuel chamber to the lower ports. In a TLUD, cold primary air enters from beneath, and the gasification is stratified/radial.

The coaxial arrangement also permits the addition of fuel as desired, in contrast to a batch-loaded TLUD.

Sailor 12-17-2009 17:27
Quote:
Originally Posted by pedro (Post 182811)
I agree. How about weighing the fuel, or using a volumetric measure, before the burn?
How about timing the burn, from lighting up to end of flame? Thoughts?
Also, how the fire was lit. 7 drops lighter fluid, or doused it with white gas?
fuel: pellets by volume (small stoves, so 1/2 cup the standard?)
times: 1) from lighting, minutes to secondary, minutes to only char
2) SP700 water 12 oz boil time (this is a standard cup, and 12 oz is one beer can of water, pretty easy to measure and agree on---researcher must, of course, you a new beer can for each test); water temp is assumed or should be noted?
3) charcoal lighter fluid, 10 drops evenly spread for starter?


Quote:
Originally Posted by pedro (Post 182811)
I agree that you can create a vacuum using a venturi, if the nozzle is pointed in the right direction. I also understand the whole concept of not leaving any voids in the flame pattern, and how this is advantageous. What I don't understand is how this stove is not a T-LUD manufactured to extremely high standards. There is no question in my mind that Nat's engineering expertise is excellent. But just look at his burner! It's like a turbine. I'm just wondering if the jump in efficiency is due to superior porting technology.
I've pointed out before and will again, that I think air flows (venturi, in tubes, etc.) are poorly understood and very important, and that we can achieve much better flow be shape, e.g., KK; old aeronautical engineers really worked hard on air intakes for engines in 30's-40's and achieved a bunch, but that knowledge is being lost.

I have also noticed that the STOVES LISTSERV people talk a lot about swirl patterns in stoves being designed around and especial 3rd, world. I've always assumed better mixing. Don't really know. Color of flame is a real test for complete combustion, which is what we are really after, and what 2ndary burn is about--complete combustion is more energy gained, less soot on pot, and blue flame.

Agfadoc 12-17-2009 18:02
But if you drink the beers, will your measurements remain constant?

Reading Gailainnes blog above, he tried pellets with not so much luck...but from what he stated, it didn't burn long enough. So if I made it capable of continuous feed, then that should be resolved.

I went to the store and they only sell 50lbs of pellets.. It was only 4 dollars but 50lbs.. man, what will I do with the rest of the pellets? I had to take a customer out to lunch and thought I would come back and get the pellets, but didn't, I have some maple chips for smoking the bbq that I'll just test out before I buy 50lbs of pellets. It will obviously not be comparable because maple will burn hotter I would assume.

If we could move air without an electric fan, say with one of those stove fans that are thermocoupled (unfortunately are $100 dollars) but maybe devise a heat generated air flow with an off the shelf thermocoupled motor, now THAT would be the cats meow. No batteries...

Sailor 12-17-2009 18:11
Quote:
Originally Posted by Agfadoc (Post 182852)
But if you drink the beers, will your measurements remain constant?
That's the beauty of my scientific approach...the more you test, the more satisfied you are, and all the other scientists understand the methodology, becuase they too must test under the same conditions. I'm sure you've noted at physics seminars you've attended...the papers speakers hand out, explaining test procedures and results. What did you think "on the 5th iteration..." meant?

Quote:
Originally Posted by Agfadoc (Post 182852)
Reading Gailainnes blog above, he tried pellets with not so much luck...but from what he stated, it didn't burn long enough. So if I made it capable of continuous feed, then that should be resolved.
Pellets seems a little slower to start, but they work great once going, are very steady, introduce fewer variables, etc.

Quote:
Originally Posted by Agfadoc (Post 182852)
I went to the store and they only sell 50lbs of pellets.. It was only 4 dollars but 50lbs.. man, what will I do with the rest of the pellets?
I bought two sacks, and felt like I was wealthy. Through the first one and well into the second a year and a half later...

Quote:
Originally Posted by Agfadoc (Post 182852)
If we could move air without an electric fan, say with one of those stove fans that are thermocoupled (unfortunately are $100 dollars) but maybe devise a heat generated air flow with an off the shelf thermocoupled motor, now THAT would be the cats meow. No batteries...
They're big and heavy. I've got a solar charger on my Reed stove, and it works great. His stove is heavy because its SS, not because of the fan. I might just spend the dough to make his out of TI and call it a day. However, if I could get clever enough with shapes to not need the fan...

pedro 12-18-2009 16:31
Quote:
Originally Posted by Big D (Post 182528)
How can I get in touch with Mat concerning the Beaner?
Okay, Matt has set up an E-bay store to sell the Beaner stoves.

http://stores.ebay.com/WorldStoveUSA

I'm gonna get one.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:13 pm

Sailor 12-18-2009 17:25
thank you. Just did!!!

Agfadoc 12-18-2009 17:33
Hey, I tried the everything nice design and made a video.. it worked ok..

I have to get that beaner...


pedro 12-18-2009 17:49
Nice burn test, man! Concerning your time to boil: you waited for the stove to start gasifying before putting your pot on, right? Do you remember how long it took from lighting to gasification? Keep up the good work.

Agfadoc 12-18-2009 17:56
it took 3:20 to really start a full gasification, and I waited until it gasified so I can keep down on the soot.

(sorry had to read my notes)

I think this design will work well for smaller pots as it seems to burn slower than the other bottom open design. It is a guess and I'll find out tomorrow when the Thermos is fully set.

I think the Thermos jets pointing upward may have an effect as well if I can channel the flames directly to the pot with a bit longer and more closed in pot stand???

Redoleary 12-18-2009 19:02
Good info, and good video, thanks for sharing.
I may knock together a few stoves and do some testing tomorrow.... we'll see.

GrizzlyAdams 12-18-2009 21:47
I am learning a lot from this thread. Thanks for posting that video. My son's have inherited my fire bug instincts and are trying out some of the designs you all are discussing.

I am curious about that beaner.

Grizz

Frawg 12-18-2009 22:04
It would sure be interesting to see an integrated discussion of the thermodynamics, aerodynamics and chemistry of this magic, and would make it easier to actually engineer one of these puppies. More than a little beyond me, though. :(

Here's to "iterative design" (trial & error?) with many hands making light work -- a tip of the hat to all of ya! :thumbup:

Sailor 12-18-2009 22:30
Frawg, you're right, and it seems even more daunting to me reading the STOVES LISTSERV, etc.--real brains, PhD's, and some smart guys too, slowing making progress...

Big D 12-18-2009 23:08
Quote:
Originally Posted by pedro (Post 183103)
Okay, Matt has set up an E-bay store to sell the Beaner stoves.

http://stores.ebay.com/WorldStoveUSA

I'm gonna get one.
Appreciate it Pedro!

Albert Skye 12-18-2009 23:13
A PhD is not necessary to understand how things work. One need only apply awareness and imagination (and remain ever engaged in countermeasures to that human tendency for insidious self-deception ;)).

.
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:14 pm

Sailor 12-18-2009 23:19
Yeah, that too.

Frawg 12-18-2009 23:45
Quote:
Originally Posted by Albert Skye (Post 183206)
A PhD is not necessary to understand how things work. One need only apply awareness and imagination (and remain ever engaged in countermeasures to that human tendency for insidious self-deception ;)).
Heh heh. ;) Well, I came close to one but not in this stuff. The last thermo, aero and chem I studied was 40+ years ago. What I remember of it could be written on a postage stamp with a big crayon. :laugh:

Okay, I do remember the ideas behind the continuity equation... but still, it'd sure be nice to have someone who understands all this stuff connect the dots for me, from all the input and intermediate variables to the output wattage and total energy.... purty pleeze? :)

Actually we could probably do okay on a macro level without understanding all the details of the underlying theory -- make a vector of all the independent variables of a particular design and use your favorite optimization algorithm to converge on "a" best solution. :rolleyes::sleep:

... but that'd take a lot of hoppin' for this tired ol' Frawg. :mellow: I'm nominating the MacGrizz clan for the project. ;)

Agfadoc 12-19-2009 00:07
Or you can just mess with it until it works, I have to say I am learning tons. I like the paint can and progresso soup can because you can pop out the can and put in another, quickly testing different designs.

I know engineers that could talk all the specs of an engine or a computer, or bullet velocities all day long but couldn't resolve an issue, turn a wrench, or hit the side of a barn to save their lives. They would run into a problem with their design, and one of the techs would come in and just look at it, and fix it for them. I always found that funny. Ehem, of course it never happened to me.. :rolleyes:

Looking forward to seeing other designs, I will be finding out the flames coming out of my little thermos, based on the everythingnice stove I tested and I have what I think is a pretty cool pot stand for it, it will screw onto the threads of the thermos and store in the base, I just need to know how high the flame will be. Now to get past the honey do list tomorrow to try it out.

Frawg 12-19-2009 00:17
I hear ya, Aggie! I kinda split the difference myself. Got tired of playing with circuits that almost worked and decided it was time to learn a bit more theory. Helped immensely. :)

I had a physics teacher once say that there were two kinds of physicists, theoretical and experimental. You could tell 'em apart easy enough. When a theoretical physicist walked into a lab, all the equipment would quit working. <rim shot> :rolleyes: :laugh: I think he was an experimental physicist... ;)

...I'm heading back to the peanut gallery to watch the rest of the show. :jj:

Agfadoc 12-19-2009 00:31
On that topic, one last thing... I have to add that I know a few people who think they know it all, basically isolationists, and a lot more that realize that you just can't know it all, but acknowledge that fact and work well with others to combine their strengths and resolve as a team to get the job done.

Frawg 12-19-2009 00:41
Amen! Wish I had the time to pitch in, but you guys are making such great strides I'd just get underfoot. I'll be happy to copy what you come up with, though... I've got this stainless steel thermos that's getting kinda old. ;)

Side note - many a tech saved my behind, as well, God bless 'em!

Anyhoo, kudos again to you guys! Good stuff all around. :)

Frawg 12-19-2009 01:19
a modest proposal

A thought occurs to me, thanks to Agfadoc's last observation.

I don't have the time and resources to do much build & test, but I'm definitely interested in what you guys come up with. So if anyone's interested in pursuing that macro level optimization thing I'd mentioned, I'd be happy to pitch in to see if we can make sense of any data you collect in a way that might help focus the research.**

Given the many bright and creative people working on the problem across several forums, I'm guessing there's a fair chance something of this nature has already been "written up in the literature". If not, maybe we can take a collective "next step" on this.

Albert, I apologize in advance for wandering off your topic. If there's
any interest in the idea we can open another thread or take it to a different site, however y'all feel is appropriate.

Late note: this collective effort strikes me as exactly the kind of thing that Google Wave might be suited for, as Angrysparrow mentioned in the other forum.

Thoughts?


~~~~~~~~

** that's actually what I had in mind with my "MacGrizz clan" thought. They have the brains and brawn under one roof, and can reduce data over dessert at the dinner table. :D

GrizzlyAdams 12-19-2009 02:12
Quote:
Originally Posted by Frawg (Post 183235)
...
** that's actually what I had in mind with my "MacGrizz clan" thought. They have the brains and brawn under one roof, and can reduce data over dessert at the dinner table. :D
appreciate the thought, but when it comes to stoves we're rank tinkerers. I like reading up on the principles, and the progeny like drilling holes in cans and burning stuff. Anyway, as Mrs MacGrizz prefers conversation "we all" can contribute to at the dinner table, chemistry and aerodynamics as topics are not encouraged :scared:

Grizz

Gailainne 12-19-2009 04:40
Really good stuff guys, enjoying this thread, I must admit I've started looking at cans and stainless steel containers in the supermarket as parts of a stove rather than what they contain again :rolleyes:. I haven't gotten to the stage of taking a tape measure along yet :lol:.

I could only get the wood pellets to work when I used a fan, but I was using cat litter pellets which are only 4mm diameter, I figured they were packing down and not allowing an air flow through them.

In the end I went back to testing using sticks and twigs, basically what I would have used while camping.

Is there a link for these thermocouple type powered fans ? I'd be interested in looking at those.

Cheers

Stephen

pedro 12-19-2009 07:17
[quote=GrizzlyAdams;18323 Anyway, as Mrs MacGrizz prefers conversation "we all" can contribute to at the dinner table, chemistry and aerodynamics as topics are not encouraged :scared:

Grizz[/QUOTE]

Oh, man, almost shot my coffee through my nose when I read that! Been there, done that brother.:laugh:
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:16 pm

Agfadoc 12-19-2009 10:05
Quote:
Originally Posted by Gailainne (Post 183244)
Really good stuff guys, enjoying this thread, I must admit I've started looking at cans and stainless steel containers in the supermarket as parts of a stove rather than what they contain again :rolleyes:. I haven't gotten to the stage of taking a tape measure along yet :lol:.

I could only get the wood pellets to work when I used a fan, but I was using cat litter pellets which are only 4mm diameter, I figured they were packing down and not allowing an air flow through them.

In the end I went back to testing using sticks and twigs, basically what I would have used while camping.

Is there a link for these thermocouple type powered fans ? I'd be interested in looking at those.

Cheers

Stephen
Here is what sparked the idea...

Eco Fan at Cabelas

But it is probably heavy, I haven't held one but I would be interested to know more about it.

Gailainne 12-19-2009 10:47
Ah that's not what I was thinking about, I saw something on BCUK a while back..

Here it is, I thought it had been developed more and was in production, although it does say on the website spring 2010. Nice concept.

pedro 12-19-2009 11:49
That's the one! Ya beat me to it. I was having a tough time finding it.

Agfadoc 12-19-2009 11:58
Quote:
Originally Posted by Gailainne (Post 183336)
Ah that's not what I was thinking about, I saw something on BCUK a while back..

Here it is, I thought it had been developed more and was in production, although it does say on the website spring 2010. Nice concept.
Thanks for the find..

Same concept just the thermo couple is located on a tube through to the stove with a switch that gives it say 6 volts vs 12 volts, just as an example..

I really like that stove, but it is the same concept we are working with here, if we could get the air circulating around between the chambers it would remain cool, jet the air.. etc, but how would we be able to make that?

Here is a discussion of thermocouple fan control:
http://www.control.com/thread/1026248943

who wants to break out their breadboard and see how small they can make the circuit?

Agfadoc 12-19-2009 12:05
Why couldn't they place it on the bottom and extend the sensor along the chamber, it would be more ergo, imho.

Sailor 12-19-2009 12:13
The forced air Reed Woodgas using a couple AA batts is lighter than the heat powered fan stove, which is the prob.

My Beaner is in the mail. thanks, guys...been looking at it for a few months, and you pushed me.

Frawg 12-19-2009 12:22
Unfortunately my breadboard gear is in boxes up in Virginia.

I'm a little confused, though. It looks like the fan control discussion as about controlling fan speed - is that what you're trying to do, or are you looking to actually power the fan with a thermoelectric generator? Or both?

Some thermoelectric generator stuff here and a pdf slide show on Producing Light from Stoves.

Seems to me I saw some thermoelectric modules at one of the electronics sites a few months ago. I'll see if I can find the links.

Frawg 12-19-2009 13:03
Interesting paper (pdf) here: Thermoelectric Power Generation from Biomass Cook Stoves.

Agfadoc 12-19-2009 13:30
Quote:
Originally Posted by Frawg (Post 183375)
Interesting paper (pdf) here: Thermoelectric Power Generation from Biomass Cook Stoves.
Good stuff.. it's what we are looking for.

Frawg 12-19-2009 13:33
May not be feasible, but here's another idea that bypasses thermogeneration altogether:
http://www.woodgaz-stove.com/

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Re: TLUD Quotes

Postby zelph » Wed Sep 08, 2010 1:17 pm

Agfadoc 12-19-2009 13:44
How much do we want from these stove, really? do we want to burn the wood faster, hotter, and have to burn more wood?

If we add a fan, it will burn more wood, hotter and faster, but if I get a boil of two cups at 5:10 from a static stove, and the benefit that we get is saving 1:00 minute from adding a fan, but have to use more fuel are we really benefiting or is this just an exercise to see if it can be done?

I love the gasification process simply because it efficiently burns the fuel with little or no soot, but what additional benefits would we get by going with a fan?

Is the effort/benefit balance enough to proceed? What happens to the stove if the circuit fails? will it still perform as a static stove? will the extra components get in the way? will the additional weight be worth the extra benefits?

Just questions that cross my mind as I know that simple is sometimes better over the lifetime of a product..

Agfadoc 12-19-2009 14:00
Where I am going with this is someone has already made the complex stove; Nat and others, someone has already made the simple stove, bushwacker etc.. what if we made a simple stove with porting and venting to maximize the heat, minimize the fuel and weight, and efficient boiling? Wouldn't that be more beneficial than creating a stove that the average person can't make?

Just some thoughts.

Frawg 12-19-2009 15:05
I'm thinking what you are, Agfadoc. The fans are great for increasing the burn efficiency, but how much is enough? From what I've read, much of the research is being done with a view to "third world" applications, motivated by resource conservation and health concerns. The basic goal seems to be to design easily built, efficient, clean-burning cook stoves to minimize impact on the planet and on human lungs. Those motivators are good, but not what drive me for backpacking use.On a side note, my original interest in thermogeneration was for charging batteries.

For my money, speeding up the water boiling isn't a big factor. As someone (Sgt Rock?) once put it, "if you're in such a hurry, what are you walking for?" :laugh:

I'm also more interested in porting and would like to learn more about the flow in these stoves. Seems to me there's a bit to be played with on the size, location and spacing of the different holes. If fuel 'X' is burning at 'Y' power level, then there's a certain mass flow rate out the "exhaust" that relates to the incoming airflow, among other things. It would be nice if we could graph out the dependency relationships among the variables.

One of the fan based designs made an issue of separating the primary and secondary air intakes, which effectively decouples the two variables. (an orthogonalization of sorts). I wonder if we couldn't achieve some level of decoupling by relocating the intake holes on the outer shell, say halfway up the side, splitting the difference between the lower and upper holes of the burn chamber. I don't envision it making that much difference, but I'll give it a try the next time I get a chance.

Who knows, though -- maybe the Beaner is the final answer. It'd be nice to have enough data to know.

Just some more thoughts... :)

pedro 12-19-2009 15:17
Quote:
Originally Posted by Agfadoc (Post 183394)
How much do we want from these stove, really? do we want to burn the wood faster, hotter, and have to burn more wood?

If we add a fan, it will burn more wood, hotter and faster, but if I get a boil of two cups at 5:10 from a static stove, and the benefit that we get is saving 1:00 minute from adding a fan, but have to use more fuel are we really benefiting or is this just an exercise to see if it can be done?

I love the gasification process simply because it efficiently burns the fuel with little or no soot, but what additional benefits would we get by going with a fan?

Is the effort/benefit balance enough to proceed? What happens to the stove if the circuit fails? will it still perform as a static stove? will the extra components get in the way? will the additional weight be worth the extra benefits?

Just questions that cross my mind as I know that simple is sometimes better over the lifetime of a product..
Very good questions, and I agree that the KISS approach is the way to go if possible. The objective of adding a fan on a gasifier is not to burn more wood faster. The additional air gets ducted to the secondary ports, which will do a couple of things: Add turbulance to the wood gas, and add oxygen to the wood gas. Both of these things will make for a more complete burn, With a lower CO output. The fan would not be used to supply air to the primary burn.

Quote:
Originally Posted by Agfadoc (Post 183397)
Where I am going with this is someone has already made the complex stove; Nat and others, someone has already made the simple stove, bushwacker etc.. what if we made a simple stove with porting and venting to maximize the heat, minimize the fuel and weight, and efficient boiling? Wouldn't that be more beneficial than creating a stove that the average person can't make?

Just some thoughts.
I am also torn between max efficiency and making the design buildable by the average person. Sure, I could break out the TIG torch and whip up something that would probably be more efficient. But then most people who wanted that would have to go and buy it. But consider this: there is a whole lot of experimentation going on by independent researchers (including you!) to see if this idea or that idea will make a difference. The same can be said for any technology that doesn't require loads of money to experiment with. Look at hammocks, for instance. There has been a lot of experimentation by a lot of people in order for us to get where we are today. There have been tons of hair-brained ideas that have been discarded. There have been several crack-inspired ideas that actually work. I think that the important thing is to do exactly what we're doing: Trying different approaches, and sharing information.

FWIW, I agree with you in the end. I don't want a fan, and I don't want to have to own a CNC mill in order to make a stove. End of rant.

Albert Skye 12-19-2009 15:18
Quote:
Originally Posted by Frawg (Post 183222)
[...] theoretical and experimental.
I know you were joking but I'm compelled to mention that experiment is of course connected to physical reality, and I find it very useful to distinguish theory/model from experiment/fact; otherwise, it seems all too easy to become absorbed in abstraction, poring over maps of maps of maps ... as it were (hence reducing connection to the very things for which those useful but inevitably incomplete/approximate maps ironically if ostensibly exist).

Quote:
Originally Posted by Frawg (Post 183216)
[...] it'd sure be nice to have someone who understands all this stuff connect the dots for me, from all the input and intermediate variables to the output wattage and total energy.... purty pleeze? :)

[...] macro level [model]
If you're implying that I am such a someone, I'm sorry to disappoint you. I see many patterns and I understand that mathematics may be the best language we have for describing them (and I wish I were fluent with it) but I find myself repelled by the unnecessarily complicated nature of human form (i.e., I admire semantics but syntax so often sucks).

In any case, I think the relative impedance between the lower and upper ports is critical to Nat's design. As the flame burns and draws air from the upper ports, it must induce enough flow between the walls (pressure reduction) that gas is drawn into the outer cylinder from the bottom ports of the fuel chamber. The geometry must also be tuned to support full coverage of the flame cap. I'm sure one can make a nice model but that's something best left to computers and engineers. ;) And I imagine Nat already has a good one anyway; worth an enquiry.

Quote:
Originally Posted by Frawg (Post 183235)
[...] wandering off your topic. [...] Google Wave [...]
No worries about being off topic; Nat's stoves are already off topic as they aren't TLUD. ;) I'm glad people find this thread inspiring and I welcome off-topic discussion (but regardless of topic, I aim for a high SNR). By the way, (and off topic ;)) I guess it's old news but I just learned of Grigori Perelman.

Be careful with Google (it's not your friend, and their slogan ought to instead read "Don't get caught doing evil!").

Quote:
Originally Posted by Gailainne (Post 183336)
[BioLite stove]
I've been told that Seebek/Peltier devices are easily damaged by overheating but I've not investigated the details.

Quote:
Originally Posted by Agfadoc (Post 183394)
How much do we want from these stove, really?
My primary objective is to reduce smoke/soot (and to contain the fire). Fans can certainly make it easier to control the behaviour of a stove but I prefer to avoid the added weight and complexity, at least when travelling.

Agfadoc 12-19-2009 16:15
So in that regard, I would like to see what the increase in distance from the gasified fire coming from the upper vents, combined with channeled heat, similar to a caldera cone, or long stove effect and see if you can somehow combine or maximize the flames at the point where the pot meets the stand to centralize the heat directly onto the pot bottom without the wasted flames pouring out the sides... Do you think that is a waste of effort or something that can be achieved?

pedro 12-19-2009 16:29
Quote:
Originally Posted by Agfadoc (Post 183432)
So in that regard, I would like to see what the increase in distance from the gasified fire coming from the upper vents, combined with channeled heat, similar to a caldera cone, or long stove effect and see if you can somehow combine or maximize the flames at the point where the pot meets the stand to centralize the heat directly onto the pot bottom without the wasted flames pouring out the sides... Do you think that is a waste of effort or something that can be achieved?
It is not a waste of effort at all! Go for it! That is IMHO why the small packable stoves are so problematic compared to household size stoves. You can't take advantage of the chimney effect. I'm also thinking along these lines. I want to make the windscreen tall enough to surround the pot all the way to the top. In previous experiments, that seemed to really increase the airflow to the secondary ports.

Frawg 12-19-2009 16:51
Quote:
Originally Posted by Albert Skye (Post 183415)
I know you were joking but I'm compelled to mention that experiment is of course connected to physical reality, and I find it very useful to distinguish theory/model from experiment/fact; ...
Yup, was joking. You make good points, obviously. :) Perhaps I write too little sometimes, but I try to avoid expounding stuff I figure you guys already know.

Quote:
If you're implying that I am such a someone, I'm sorry to disappoint you. I see many patterns and I understand that mathematics may be the best language we have for describing them (and I wish I were fluent with it)
Cool! I am ( or more accurately 'was') reasonably fluent with the math and am also reasonably experienced at developing math models from fundamental principles. Mostly in EE, though. That's why I'm looking for someone who can paint the whole picture for me. IME, someone who really understands a subject can tie everything to first principles pretty succinctly. I'm getting a lot of education from all y'all. I just wish there were a Dr Feynman around. ;)

Quote:
I'm sure one can make a nice model but that's something best left to computers and engineers. ;)
I are one and am not unacquainted with the process, as are several others here. ;) FWIW, I am finding bits here and there in some of the published papers.

Quote:
...I aim for a high SNR).
BTDT, with Eb/No, BER, etc., ad nauseam. ;) (sorry, couldn't resist! )

Quote:
By the way, (and off topic ;)) I guess it's old news but I just learned of Grigori Perelman.
Cool read. One of my blind spots is topology. :(

Quote:
My primary objective is to reduce smoke/soot (and to contain the fire). Fans can certainly make it easier to control the behaviour of a stove but I prefer to avoid the added weight and complexity, at least when travelling.
...and the congregation said AMEN!! :thumbup:

Great thread & topic, Albert -- Thanks! :D

Redoleary 12-19-2009 18:26
Thanks to everyone for all the info being posted, this is a great thread.
I whipped up a few stoves today, one being a single wall model that I tried putting the secondary holes inside, and outside the wind screen. That one never really seemed to take off, but would likely do OK with a different pot stand. The other stove is a double wall with a cone suspending the burn bucket. I wonder if it would be better with a smaller diameter cone, and I wonder if a gas that is gently warmed over a four inch length as it rises to the secondary holes gains any velocity by the narrowing cone? My answer to that is: I wish it did but I don't think it does.:)
So here it is todays video, hopefully we can all learn from my failures.:confused:


Good luck,
RED

Frawg 12-19-2009 18:45
Thanks for posting that, Red!

I'm inclined to agree with the smoke being related to insufficient airflow. It's clearly from incomplete combustion, but from what cause. Could be the size of the air inlets, but might also be from back pressure induced by putting a pot over the exhaust area. And maybe a cold pot cools the exhaust vapor enough to partially extinguish the secondary burn. I've seen similar behavior when I put an aperture disk atop the burn chamber, so I'm leaning toward back pressure as a culprit. At any rate, the relative size of the exhaust aperture has to be a significant system variable, IMHO.

Good work!

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