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Post by independentenergy on Jan 22, 2017 22:35:32 GMT -8
I built something even I like.
but then my focus has shifted to something with vertical feed.
Perhaps this system may develop in this direction. . .
thanks Peter for the explanation
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Post by pinhead on Jan 23, 2017 5:03:36 GMT -8
Back wall of the firebox. As for the longer flame path....I agree about heat up time, but....my opinion is that you need a little more time in the three T equation. We are already maxing temp, you've got turbulence, you just want to keep it all there for a moment longer when things are crazy to stabilize your charts. Just a guess! I agree -- in my experience, any time there's flame coming out of the riser the burn is inefficient. Adding an insulated riser extension has done the trick for me on a couple of stoves. Most of my stoves end up having a taller-than-normal riser because my clay-ash-perlite mix isn't as insulative as something like a superwool riser. If not a taller riser, maybe insulate your current riser a bit more to further elevate the temperatures? |
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Post by drooster on Jan 24, 2017 13:27:44 GMT -8
I have to complement Peter on your casting skills,
all very neat, very careful.
Just to be clear (already partially explained) how is runaway mode a bad thing?
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Post by peterberg on Jan 24, 2017 13:42:23 GMT -8
It's a very scary phenomenon, the whole thing is shaking and the flames are spitting out the air inlet. It's the noise and violence of a chimney fire, contained inside the core. The end temperature rise to alarming levels and it's also coupled to black smoke coming out the chimney, though not at every occasion. In short, you don't want that inside your living room.
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Post by satamax on Jan 25, 2017 3:52:47 GMT -8
Peter, if it weren't for the black smoke. It would be wonderful to harness it!  |
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Post by peterberg on Jan 25, 2017 3:59:07 GMT -8
I see what you mean, it's a very violent dwarf. And of course, the construction is a bit more complicated as compared to a plain vanilla batch box. But on the other hand it's a small and short core, short riser, ideal for a cooking range. So there are advantages to gain once it is tamed down a bit.
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Post by DCish on Jan 25, 2017 5:54:29 GMT -8
You know, I thought I knew what thermal runaway meant, but now I'm second guessing myself based on your description. Any video of this?
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Post by peterberg on Jan 25, 2017 6:55:17 GMT -8
No video of a thermal runaway, sorry. I stayed close to the stove and held a piece of steel to the glass, for fear it was blown out... It rattled against the core and made progressively more playroom for itself by doing that. Although, during the last video from above in the riser it was nearly there, you are able to see the flames coming out of the riser in an irregular pulse fashion.
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Post by smartliketruck on Jan 25, 2017 19:57:47 GMT -8
What surprises me is the fact that the cast halves seems to stay whole, without cracks in sight. Do you figure this only due to properties of the Golite 135, are the walls of this any thicker than previous batch box moldings like say for examples the two sketchup files on the batchrocket.eu site? (Did I miss dimensions as I was skimming this thread to catch up?) I'm asking because I'm considering casting a small (3"or 4") bisected regular batch box with thicker walls for easier setup and teardown, having to only make two molds is also certainly appealing. |
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Post by peterberg on Jan 26, 2017 1:27:55 GMT -8
I'm inclined to think it has something to do with both the Golite 135 and the layout of the core. Since the port is high up, there's no extreme heating up of the ceiling and upper wall parts here. As for the regular batch box: it would be wise to keep the flat ceiling as a separate piece, helps greatly to keep the thing as a whole.
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jono
Junior Member
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Post by jono on Jan 26, 2017 15:47:47 GMT -8
fantastic timing peter. the other combustion core i made fell to pieces on a protest ride last autumn (fall) and i have to build a new one for an event on Saturday, so this thread came just in the nick of time for me. I spent the last four hours building a mold and filling it with refractory concrete. I'll start a new thread in catering tomorrow to document the build.
amazing how powerful that shape is. is the reason that it is more powerful than the classic batch box simply because the combustion gasses have a more direct route up?
mat, do you want to introducing the secondary air at the bottom of the port instead of the top to make it pass through more of the turbulence. sounds like a good idea to me
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Post by matthewwalker on Jan 26, 2017 16:39:40 GMT -8
Yes, exactly. A simple floor channel all the way to the back, and a short riser to about an 1" from the port.
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Post by keithturtle on Jan 26, 2017 23:32:19 GMT -8
Didn't I tell here I worked as a mold maker long ago? So, if this turned out to be a winner, would you consider vacuforming both halves of the mold and making them available? Or is there a better way to mass replicate this design? Thanks, Turtle |
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grga
Junior Member
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Post by grga on Jan 27, 2017 0:52:30 GMT -8
Peter, this design and cast looks very impressive. Hope you will manage to calm down its behaviour. Regular batchbox design requires large depth of the finished fireplace whereas this design is not and can therefore be used in more slim modern designs of the fireplaces. Similarly as a sidewinder but I like this design more.
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Post by peterberg on Jan 27, 2017 1:39:34 GMT -8
amazing how powerful that shape is. is the reason that it is more powerful than the classic batch box simply because the combustion gasses have a more direct route up? Hi Jono, from the perspectice of the firebox' aerodynamics this port is like an opening which is a straight route, yes. But also, probably more important, this port is a smaller percentage of the riser and consequently the pressure drop is larger as compared to the original design. So there's a firebox full of fire with an atmospheric pressure opening at one end and an lower pressure opening at the other. Add the notion that the combustion is ramping up, seemingly without a limit, speeding up the combustion rate and the level of underpressure in the port. The net result is a blown fire, much more so than the straight batch box, easy to see why it is effortless running out of hand. Widening the port could be a solution but I like the wildly turbulant environment in the riser. I'll try the tight door first, maybe incorporating the main air inlet in the secondary air duct could be an alternative. The air feed will be coming from the top of the firebox by doing so, might be a better way to calm it down. Just thinking out loud... |
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