Ralf
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Post by Ralf on Sept 25, 2018 12:25:20 GMT -8
I see a little difference between this setup and travis' one that might be of interest. He shaped the opening at the top of the tapered riser more like a slit/port and not as a square hole and has only 140 mms top gap above that with a system size of 150 mm. Could it be that this confined space above the heat riser acts a little like the shoe box, providing futher mixing and combusting the rest of the 500 ppm CO ;-) ? Would be an easy thing to make a U-shape out of ceramic fibre board and put it upside down on top of a second "port" at the top of a tapered geat riser. Unfortunately I don´t have a ready batch box with tapered riser at hand (will come), I´d try it immediately.
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Ralf
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Post by Ralf on Sept 15, 2018 1:55:39 GMT -8
Thanks very much for your answer, I get a much better picture now! At the moment I consider a slightly tapered riser for my next build, since the bell won´t be that high and I can put the BBox a little higher that way for loading comfort. For my 18 cm system I arrive at the needed riser volume when I put a 50 cm piece tapering from 18 cm to 30 cm (calculated with a truncated cone shape) on top of a 30 cm high straight port/rams horn section.
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Ralf
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Post by Ralf on Sept 14, 2018 1:36:57 GMT -8
Peter, I´m trying to wrap my head around the flue gas diagrams you provided. It seems that the initial short peaking of the CO that I saw in most "standard" Batchbox analyses is gone, however the overall CO during the full burn seems quite a bit higher than in the "standard" design.
Apart from the hard physical numbers you also got the impression that the heat output is bigger compared to a standard BB system of the same size right ?
I also wonder if the taper riser system will perform even better if scaled up (150 /180 /200 mm), a tendency that I also see in the diagrams of the standard design. However if the capped-funnel-riser gets larger its use might be limited to wider bell shapes because of potential downflow restrictions...
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Ralf
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Post by Ralf on Sept 11, 2018 3:57:16 GMT -8
Hi Peter, could it be that the high efficiency and power is partly due to using that fibre board throuhgout ? There´s nothing that robs any heat from the combustion and also almost no mass that has to heat up to operating temperature. Can you make a guess on how a firebrick version of this that´s only insulated on the outside would perform ? (apart from me having no idea yet of how this could be built without an awful lot of cutting)
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Ralf
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Post by Ralf on Sept 10, 2018 12:43:25 GMT -8
Hi, the principle of five minute risers is also used in ceramic kilns used for Raku, a kind of ceramic that is fired (and cooled) very rapidly. Search for "Ochsner Kübel Raku" to see pictures. As they see a lot of thermal stress and abuse I think such a riser should last quite long. However there´s one additional detail the potters use to keep the ceramic fibre in place: They "sew" the ceramic fibre blanket to the supporting metal casing. Knobs with two holes are either made of pre-fired fireclay ceramics or Inconel metal, Kanthal wire is used as a sewing thread to fix them on the inside of the fibre blanket, and poked through to two corresponding little holes in the metal casing. If you want to be 100 % sure to have no sagging try this.
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Ralf
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Post by Ralf on Sept 6, 2018 23:03:03 GMT -8
Hi Peter, just for my understanding: Heat riser behind the port is round and system size to enable the rams horn double vortex. Above that does it taper into a cone shape or widen abruptly to a bigger "riser box" that is partly capped at the top? If it´s the latter it seems like a logical progression of your findings in the "Mallorca build", where there's already a small shape transition after the lower part of the riser. Would be something to consider for my next build... Ralf
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Ralf
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Post by Ralf on Sept 5, 2018 0:18:25 GMT -8
Is it possible to build a batch box bell that's directly connected to an existing wall (in my case an almost 60 cm wide mortared natural stone wall inside the house) so I can make use of the large mass of the wall as additional heat storage ? If I build the bell wall at close proximity to the existing wall and fill the gap with mortar to provide the thermal connection, will this work ? The upper part of the bell will be double-walled with a layer of firebrick inside.
Thanks for feedback !
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Ralf
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Post by Ralf on Mar 25, 2018 13:39:03 GMT -8
Hey Luke, How big is the room you are heating with the stove ? Thanks to all for the shared information!
Ralf
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Ralf
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Post by Ralf on Oct 24, 2017 10:38:27 GMT -8
Hi Peter,
I followed a video of your talk at the RMH Jamboree and you said the CO is the last compound of the combustible gases to burn. Maybe there´s not enough time for the final burn of CO because the speed in an "updraft" condition like this is too high (only guessing) ?
In your first post you liked the second version better, what is the difference, secondary air supply ?
I guess since the ceiling is gettig so hot embedding a cannel for the secondary air there would work fine, or is that thought misleading ? And finally: is this batch lit at the top to start it ?
Big big thanks for your generosity to share all this wonderful findings with everyone !
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Ralf
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Post by Ralf on Jun 2, 2017 21:14:59 GMT -8
Hi Klemen, I also think your adjustable air inlet design is brilliant. A question that comes to my mind is: Will there be enough space behind the door to contain the sides of the "valve" flap when it is fully closed ? After all there´s the bricks of the floor right where these sides will go, or do I get that wrong ?
Good luck with your build, looks awesome !
Ralf
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Ralf
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Post by Ralf on Feb 28, 2017 4:23:55 GMT -8
Hi all,
from the similar "steaming behaviour" of my stove I concluded that while the volatile compounds of the wood burn (and they contain hydrogen) water vapour is formed, and as soon as they are gone there´s only the carbon matrix (charcoal) left that combines with oxygen to CO and subsequently CO2. No hydrogen involved there, no water formation, invisible exhaust.
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Ralf
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Post by Ralf on Jan 20, 2017 14:30:36 GMT -8
Hello Peter,
could you please explain "thermal runaway mode" ?
And thanks for sharing this super ineresting development here !
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Ralf
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Post by Ralf on Jan 17, 2017 4:50:09 GMT -8
Any news from the ceramic rocket kiln, I wonder if it was a success ?
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Ralf
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Post by Ralf on Jan 17, 2017 4:48:12 GMT -8
Hi Manuel, thanks for your explanations of the barrel-flue-junction, much appreciated. I presented my version of this HERE. Just scroll down a little, it´s the second plenum that´s described.
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Ralf
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Post by Ralf on Jan 4, 2017 2:12:24 GMT -8
Yep, I was obviously just lacking that very detail, superb ! Looking forward to see how it performs, since my build might take a few months until finished.
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