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Post by shilo on May 18, 2015 20:01:17 GMT -8
this double riser version the same as Matt's core in that it can function as just a core, without a chimney, but not very well and with severe cold start problems.
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Post by DCish on May 19, 2015 3:34:52 GMT -8
Is this double riser version the same as Matt's core in that it won't function as just a core, without a chimney, as a straight batch box would? Incidentally, the only reason a classic rocket core functions well without a chimney is because the afterburner *is* a stubby chimney. Add a stubby chimney to this core or to Matt's and it will function just as well as a classic rocket core with no heat harvest. Put a bunch of thermal mass after either of them and they both will need a taller chimney at the end to function well. Draft has to come from somewhere, and is a function of both height and temperature differential.
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Post by Daryl on May 19, 2015 8:19:57 GMT -8
Is this double riser version the same as Matt's core in that it won't function as just a core, without a chimney, as a straight batch box would? Incidentally, the only reason a classic rocket core functions well without a chimney is because the afterburner *is* a stubby chimney. Add a stubby chimney to this core or to Matt's and it will function just as well as a classic rocket core with no heat harvest. Put a bunch of thermal mass after either of them and they both will need a taller chimney at the end to function well. Draft has to come from somewhere, and is a function of both height and temperature differential.
Sort of. Depends on the definition of a rocket. Mostly, these are starting to look like basic burn chambers.
Downdraft gasifiers with rams are similar to the "rockets" you guys are putting together. Built around multiple channels/chambers. There is little difference between the two. A riser isn't necessary.
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Post by johndepew on May 19, 2015 9:02:04 GMT -8
Sorry, I should have been more clear with the question.
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Post by DCish on May 19, 2015 16:56:34 GMT -8
Downdraft gasifiers with rams are similar to the "rockets" you guys are putting together.
Sounds interesting, I'm not familiar with these. Have any links to good examples?
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Post by Daryl on May 19, 2015 17:44:11 GMT -8
Downdraft gasifiers with rams are similar to the "rockets" you guys are putting together.
Sounds interesting, I'm not familiar with these. Have any links to good examples?
I'm kinda in a rush but I pulled this off the internet as a visual example. You can do an internet search on downdraft gasifier furnaces and find many with dual chambers with a venturi.
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Post by peterberg on May 20, 2015 0:43:24 GMT -8
You can do an internet search on downdraft gasifier furnaces and find many with dual chambers with a venturi. True, but... all of the downdraft gasifiers bar one (to my knowledge) work with forced draft. One wouldn have a hard time to find a horizontal one without the help of a fan. Blown furnaces are really old, see the example of an updraft blacksmith's fire augmented by large bellows. The best feature of rocket stove variants is the simplicity of the things. Granted, in most of the cases the riser is acting as a draft enhancer. That is getting more vague now due to the search for more compact combustion cores. Both of the riser-less prototypes does need a proper chimney to work. When that is what it takes to get a compact and low core for a cooking range, so be it. In my opinion of course, which is prone to change from time to time.
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Post by Daryl on May 20, 2015 2:20:02 GMT -8
You can do an internet search on downdraft gasifier furnaces and find many with dual chambers with a venturi. True, but... all of the downdraft gasifiers bar one (to my knowledge) work with forced draft. One wouldn have a hard time to find a horizontal one without the help of a fan. Blown furnaces are really old, see the example of an updraft blacksmith's fire augmented by large bellows. The best feature of rocket stove variants is the simplicity of the things. Granted, in most of the cases the riser is acting as a draft enhancer. That is getting more vague now due to the search for more compact combustion cores. Both of the riser-less prototypes does need a proper chimney to work. When that is what it takes to get a compact and low core for a cooking range, so be it. In my opinion of course, which is prone to change from time to time.
Well, DD gasifiers are also different in that they are also pulling the gases through the coals, and not all Js and Ls work that way.
My posts have been based on my opinion that multiple chambers in all configurations are possible and not uncommon in commercial stoves. A riser isn't necessary. But then, I've always been a big believer in channels over bells. From my experience, the draft is stronger.
One issue I wonder about is the amount of air being pumped into the new compact stoves. Maybe that is also impacting the draft. Not sure.
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Post by johndepew on May 20, 2015 7:35:27 GMT -8
True, but... all of the downdraft gasifiers bar one (to my knowledge) work with forced draft. One issue I wonder about is the amount of air being pumped into the new compact stoves. Maybe that is also impacting the draft. Not sure... In my look at gasifiers, forced air seemed to be pretty much universal, which kind of turned me off of the idea. Isn't the amount of air at running stage pretty much consistent with traditional rockets? Matt's secondary system (I believe) just changes the proportions of primary to secondary, using the same total of 25% system CSA, or at least that's how I built mine, and it seems to be working well. I only have a little experience with classic J-tubes, but if my memory is correct, don't they typically get throttled down to that same 25% CSA during the burn?
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Post by johndepew on May 20, 2015 7:39:12 GMT -8
I guess in these brand new iterations with secondary and third-ary and maybe fourth-ary air supplies that may be changing though. Probably a question for shilo
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Post by shilo on May 20, 2015 8:02:02 GMT -8
we try to stay under the 25% total. something around 10% primary and 12% all the other together. we have no testo so it's only a guesswork and we don't put a proper door yet
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Post by shilo on May 20, 2015 8:08:56 GMT -8
adiel opened the stove and report that some of the brown clay-perlite mortar turn to the regular red clay like usual but part of it turn to white glaze thing that he didn't saw before. like porcelain.
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Post by Daryl on May 20, 2015 8:28:57 GMT -8
Isn't the amount of air at running stage pretty much consistent with traditional rockets? Matt's secondary system (I believe) just changes the proportions of primary to secondary, using the same total of 25% system CSA, or at least that's how I built mine, and it seems to be working well. I only have a little experience with classic J-tubes, but if my memory is correct, don't they typically get throttled down to that same 25% CSA during the burn? I am curious about the amounts of oxygen and drafting issues. Another thought is the oven not helping matters. But you say yours works fine so...who knows.
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Post by johndepew on May 20, 2015 9:07:22 GMT -8
Sorry, my (heating) stove uses Matts secondary air supply, but in an otherwise straight batch. I haven't installed one of matt's cores. My cookstove in progress is just a short side riser and very low firebox. I'm waiting to see where this goes before moving ahead with it too much. The core is still exposed, so I can change it very easily if I decide to. Didn't mean to misrepresent myself. I've only experimented with matt's core outdoors, with mixed results, basically what shilo said above. Severe cold start issues and not super functioning as just a core with no proper chimney. if I add some sort of stubby riser to get it going, it works alright, but I've really not gotten too serious about it yet.
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Post by pyrophile on May 21, 2015 1:37:15 GMT -8
Downdrafters can be with forced air or with natural draft. Of course, natural drafters interest us more! The principe is very simple, a few research on google will help! Sorry, I am busy, I have to go! Benoit
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