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Post by mwalimu on Oct 19, 2014 2:42:59 GMT -8
Hi there,
I'm working for a long time with stoves an about 15 years ago I designed and produced even in series sort of a rocket mass heater in Tanzania. Without knowing it.
Now I came to the topic of rocket stoves. I built one, and hearing the sound, I remembered, my Kitchen stove w/baking oven and additional mass was a rocket stove! It had a V-feed, a horizontal metal burn chamber attached to the top stove plate of 3' x 2' and a total flue of about 3 meter / 10 ft. It produced no smoke and we fired everything which was combustible.
But to my project: Now I live in Germany an everything self-made in now strictly verboten and controlled by the Kamin-Blockwart / Chimney Gestapo. So I need something with a horizontal chimney producing no smoke nor smell nor steam. So I'm thinking about features a follows:
-Batch feed -bell style -cooling down the exhaust gases to room temperature, or say 30°C -lining the last bell floor wit something waterproof and a connection to the sewage system for the condensed water -It's in an old farmhouse and the purpose the heater is just to keep the house warm enough for restoration work and keep the plumbing from freezing. -The fire chamber with two bells will be in the upper floor, --one vertical --one like a bench, because it's under the window -and then go down through the ceiling and adding one or two bells for ultimate cooling down the exhaust gasses. -I expect no draft at the end and will release the gases through the wall in a horizontal rain gutter pipe, so it can go up or or down to the sewage system. -I could add a fan / have it already, but I like to be without.
I know it sounds mad somehow, but the real interesting thing is to get even the condensing heat out of the exhaust gases, which will come to a efficiency of more than 100%, like modern gas heaters.
What I have already is a lot of low grad burnt bricks, chimney pipes with 150 and 120 mm diameter (6 and 5 inch) and lost of very heavy clay.
I read a lot in permies.com and in this forum, and worked through to the stove.ru site.
Another not yet tried feature:
What I want to try out also is the Idea of Igor Kuznetsov from stove.ru to connect the burning chamber/riser with the first bell through a dry wall/crevice. He writes of following advantages: - heavier ballast gasses like steam and nitrogen can pass out directly to the bottom of the first bell. - some already burnt / warm gasses can come in an make the combustion hotter. - if there are embers (= coke) in the feeder / burn chamber and some water vapor (coming back from the bell) is passing over it, it will produce hydrogen, which adds again calorific value and reduces water vapor in the exhaust.
I'm aware, that this will kill the rocket effect to a great part and the fire will burn smoother. But if this works, it will also help to separate the heat from the ballast gasses and help to cool them down more rapidly. So the riser has to be bigger in diameter and the slot /crevice on a side with low turbulence /blast.
I also expect that the burn with reduced blast will reduce the welding / cutting torch effect of burning steel parts, so that a metal riser can be used.
So far my theory. Any ideas and comments from you? Thanks in advance!
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Post by photoman290 on Oct 19, 2014 2:55:56 GMT -8
can't help,but we also have a chimney gestapo in the uk. they work in conjunction with the insurance gestapo.
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Post by Deleted on Oct 19, 2014 3:22:14 GMT -8
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Post by mwalimu on Oct 19, 2014 5:37:35 GMT -8
I talk about something different: During gasification, the coal is mixed with oxygen and steam while also being heated and pressurized. During the reaction, oxygen and water molecules oxidize the coal into carbon monoxide (CO), while also releasing hydrogen gas (H2). This process has been conducted in both underground coal mines and in the production of town gas. C (as Coal) + O2 + H2O → H2 + CO In the past, coal was converted to make coal gas (town gas), which was piped to customers to burn for illumination, heating, and cooking. en.wikipedia.org/wiki/Coal#GasificationSo steam, meeting hot embers will produce Hydrogen and Carbon monoxide, both combustibles. Igor Kuznetsov found out through measurement that the heat exchanger of his stove collected more heat than the heating value of his wood. So he suggested that this could be from the effect of coal gasification. He also found no condensed water even in very cold exhausts, which he also connected with this phenomena. About perpetuum mobile and calorific value technology, here is something from German Wikipedia
Bei Wirkungs- und Nutzungsgradangaben ist stets anzugeben, ob diese sich auf den Heizwert Hi (früher Hu) des eingesetzten Brennstoffes oder auf den Brennwert Hs (früher Ho) beziehen. Um die Wirkungs- und Nutzungsgrade von Kesseln, die mit verschiedenen Brennstoffen betrieben werden, vergleichen zu können, eignen sich lediglich brennwertbezogene Angaben, da nur diese die gesamte im Brennstoff enthaltene Energie nennen. Die theoretisch erreichbaren Wirkungs- und Nutzungsgrade liegen bei Öl-Brennwertkesseln bei 100 %, wenn mit Hs, und 106 %, wenn mit Hi gerechnet wurde. Bei Gas-Brennwertkesseln werden maximal 100 % mit Hs und maximal 111 % mit Hi berechnet erreicht. Here some info from a gas heater producer: www.viessmann.com/com/en/products/Gas-fired_condensing_boilers.htmlEnglish Wikipedia: en.wikipedia.org/wiki/Condensing_boilerSo the calorific value of a combustible is always excluding the amount of energy in the water vapor. Condensing the water releases additional heat, which creates efficiencies over 100% Hi. With wood it is even more, as it is always somehow humid. There is vapor from the combustion process as well as water which is converted to steam during combustion. To get the heat out of this vapor would be a big advantage. There is a German company having a heat exchanger called Carbonizer for wood burning stoves and heaters, but it is very expensive, 3000 € I think. for wet fuels an increase in efficiency is possible up to 35%, according to this site: link.springer.com/chapter/10.1007%2F978-94-011-1336-6_52#page-1So I'm not talking about peanuts and it's a well known practise. What I find important is to do this on a low-cost base for small heaters. Bell shaped Mass heaters could be a possibility to cool down exhaust gasses to ambient temperature.
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Post by mwalimu on Oct 19, 2014 5:45:39 GMT -8
can't help,but we also have a chimney gestapo in the uk. they work in conjunction with the insurance gestapo. In the long run I try to make such stoves legal, by getting approval as a Kachelofen / Grundofen / masory heater. But for the experimenting, it has to be done undercover... BTW, a batch heater seems better comparable to a masonry heater than a j-feed mass heater with drum.
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Post by Deleted on Oct 19, 2014 5:52:57 GMT -8
Aberglaube Superstition
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docbb
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Back from ZA
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Post by docbb on Oct 19, 2014 5:53:20 GMT -8
a realy interesting project and this one too
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Post by mwalimu on Oct 19, 2014 6:32:41 GMT -8
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Post by mwalimu on Oct 19, 2014 6:38:42 GMT -8
a realy interesting project and this one too The outside design could be similar to this, even the bench, but as far I see it's a conventional masonry heater.
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Post by peterberg on Oct 19, 2014 6:42:43 GMT -8
I'm aware, that this will kill the rocket effect to a great part and the fire will burn smoother. But if this works, it will also help to separate the heat from the ballast gasses and help to cool them down more rapidly. So the riser has to be bigger in diameter and the slot /crevice on a side with low turbulence /blast. mwalimu, welcome to the boards. You're good in writing a lot of theory. But, the proof of the pudding is in the eating so I like to see a stove which do all this. What I do know is this: the batch box concept and every rocket heater for that matter, is heavily depending on high gas velocity in the burn zone. When you slow this process down there won't be clean combustion anymore. As far as I know, Igor Kusznetsov never measured his stoves, so his so-called dry joint theory isn't proven as yet. Igor Kuznetsov found out through measurement that the heat exchanger of his stove collected more heat than the heating value of his wood. So he suggested that this could be from the effect of coal gasification. He also found no condensed water even in very cold exhausts, which he also connected with this phenomena. Such measurements as you are refering to above has never been done. Igor would need a calorimeter room for that but he doesn't even use a gas analizer. And above all, he only publisized the theory and didn't prove anything. I am awaiting your proposed stove with great anxiety and I very much like to see proof which is measurable, transferable and repeatable.
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Post by mwalimu on Oct 19, 2014 6:43:07 GMT -8
Does anybody have some drawings of the feeder / firechamber of a batch feed mass heater stove? Or some links to it? I need some starting point.
Thanks in advance.
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Post by Daryl on Oct 19, 2014 7:05:09 GMT -8
can't help,but we also have a chimney gestapo in the uk. they work in conjunction with the insurance gestapo. In the long run I try to make such stoves legal, by getting approval as a Kachelofen / Grundofen / masory heater. But for the experimenting, it has to be done undercover... BTW, a batch heater seems better comparable to a masonry heater than a j-feed mass heater with drum.Not really. A J is using the same channel system. Both styles are masonry heaters. The materials used and shapes throw people off.
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Post by Deleted on Oct 19, 2014 7:11:11 GMT -8
Refering to your belief you could gain calorific value from hydrogen produced by steam.
Your link to Viessmann is valueless. For a wood burning device you cannot regain as much energy, if any, by condensation as with devices using oil or gas.
Burning methane produces about 2.2 times more water than its weight. Wood hardly enough for any condensation at 55°C.
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Post by mwalimu on Oct 19, 2014 7:14:33 GMT -8
I'm aware, that this will kill the rocket effect to a great part and the fire will burn smoother. But if this works, it will also help to separate the heat from the ballast gasses and help to cool them down more rapidly. So the riser has to be bigger in diameter and the slot /crevice on a side with low turbulence /blast. mwalimu, welcome to the boards. You're good in writing a lot of theory. But, the proof of the pudding is in the eating so I like to see a stove which do all this. What I do know is this: the batch box concept and every rocket heater for that matter, is heavily depending on high gas velocity in the burn zone. When you slow this process down there won't be clean combustion anymore. As far as I know, Igor Kusznetsov never measured his stoves, so his so-called dry joint theory isn't proven as yet. Igor Kuznetsov found out through measurement that the heat exchanger of his stove collected more heat than the heating value of his wood. So he suggested that this could be from the effect of coal gasification. He also found no condensed water even in very cold exhausts, which he also connected with this phenomena. Such measurements as you are refering to above has never been done. Igor would need a calorimeter room for that but he doesn't even use a gas analizer. And above all, he only publisized the theory and didn't prove anything. I am awaiting your proposed stove with great anxiety and I very much like to see proof which is measurable, transferable and repeatable. You are right. He has a lot of theory and talking this in length. So the crevice is not a must for my stove. If I get a clean combustion, the normal batch box rocket heater will do it for me. I just thought about getting all advantages in one time. Maybe the dry wall / slow rocket heater combination should be tested separately. It's fine to have you here as a specialist. My biggest questions are: -Can the gasses be cooled down so far that a draft would be established by sinking gasses or do I need a fan? -How can I cool down the gasses to ambient temperatures? Or below condensing point? -Will the gasses be cool enough to sink down to the ground floor bell? Or will the ground floor bell produce a draft to pull them down? I thought about putting a water tank inside the top of the last bell to have a quick heat exchange and storage compared to bricks at low temperature. Water collects four or five times more heat than bricks. The lukewarm water could be transferred to a radiator by convection to cool down even more. But for keeping the house a bit warm during winter the last bell will not be very warm, as it is standing on the cold ground an leaning towards two cold brick walls. But when heating a house to warm living conditions, cooling down the exhaust will be more complicated.
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Post by mwalimu on Oct 19, 2014 7:26:25 GMT -8
Refering to your belief you could gain calorific value from hydrogen produced by steam. Your link to Viessmann is valueless. For a wood burning device you cannot regain as much energy, if any, by condensation as with devices using oil or gas. Burning methane produces about 2.2 times more water than its weight. Wood hardly enough for any condensation at 55°C. link.springer.com/chapter/10.1007%2F978-94-011-1336-6_52#page-1 If you check this link, you see that it's normal procedure in wood chip heaters and that they take out 20 up to 35% condensing heat with moist wood chips. But in one thing you are right 55°C is not cold enough. You have to go down to 30 °C. And that's the problem I'm working on. 30°C could be used for central floor heating. But I will also look for other means, e.g. using the last bell as a lightweight air/air heat exchanger.
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