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Post by satamax on Aug 14, 2012 15:34:05 GMT -8
Mathew, yep it might make a nice draft. I'm under the impression that it is more drafty than before. Tomorow, i'll drop the tube inside, put just a little bit on top and see what this does Donkey, i was thinking, to put a tube between the bottom of the barrel to the top of the bell, then make the exhaust tube exit at the bottom. Reverse it from the curent setup. But space is too tight. I'll just try it with no tube, as explained above, to see how this works. Such a contraption can extract more heat just by being a flow "dampener" slowing it down in the big volume, so heat exchange is longer.
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Post by peterberg on Aug 15, 2012 1:49:52 GMT -8
Mathew, yep it might make a nice draft. I'm under the impression that it is more drafty than before. Tomorow, i'll drop the tube inside, put just a little bit on top and see what this does Without the tube inside, and the exit hole at the top this could work probably better but not excellent. When the bottle is acting as a real bell, imagine the top of it will be too hot to the touch within mere minutes. In fact, heating up of the lower regions will come last and the bottom end below the exhaust will stay relatively cool. It's true, at first I couldn't believe it either. Due to room constrictions, maybe you could lead the exhaust duct on front of the bell. Easier to access as well, but you have to decide.
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Post by satamax on Aug 15, 2012 2:04:07 GMT -8
Thanks a lot for the idea peter. Tho, just 90 degrees between intake and exhaust, would it work?
I love the way it draws now.
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Post by peterberg on Aug 15, 2012 6:06:55 GMT -8
Thanks a lot for the idea peter. Tho, just 90 degrees between intake and exhaust, would it work? Not sure, the proof of the pudding is in the eating, as always. As long as the exhaust is below the intake you'll stand a good chance it will work properly. I've seen a bell system like that running quite nicely with the intake straight above the exhaust and only about 6 inches between them. A 60 liter oil drum on top of a box stove, the drum got so hot the paint burned off. About the draw, the bell construction is renowned for its low friction in the smoke path.
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Post by satamax on Sept 3, 2012 3:33:19 GMT -8
So guys. I've droped the siphon tube inside the bell, and reconected the elbow directly on top of the bell, so it's like there's no tube inside, i exctract more heat that sure. Thouhgt, a bell would be better. I think i'll stop fiddling with this for the moment. And think about getting rid of blowback when it's windy.
Thanks a lot.
Max.
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Post by satamax on Sept 25, 2012 6:04:15 GMT -8
Hi everybody!
Well, i've tried a kind of P chanel onto this one. Doesn't work at all. 16cm wide, curved like the bottle, 1cm away, bout .8mm hanging down. Ney workey, smokes back, stove is temperamental etc. Dunno why.
Bye.
Max.
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Post by peterberg on Sept 25, 2012 7:13:04 GMT -8
Hi Max,
First, what's the c.s.a. of your feed tube and tunnel? The channel should be about 5% of system size. The 16 cm2 (2.48 sq.in.) you've made this suggest the system size ought to be 320 cm2 (49.6 sq.in.). That's a little bit larger than a 20 cm dia (8") tunnel.
That's awfully large for such a stove, so I've got the impression the p-channel is at the large side of things. The experience of Donkey seem to confirm that. At first, his proto-channel was made too large on purpose which made his stove too temperamental, smoking back and things like that.
I'd suggest you do the maths and rework the channel accordingly. On top of that, the plate of the channel is best kept 2" (5 cm) higher and wider at both sides than the feed.
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Post by satamax on Sept 25, 2012 9:19:48 GMT -8
Ok Peter. It's a 6 incher. So my P chanel is too big. Bout two times too big. And i didn't know that it should be higher than the feed tube, so it's only 1cm higher. Would making this actual P chanel 16cm wide, with only a 5mm gap on the whole width work? I gonna try it right now.
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Post by peterberg on Sept 25, 2012 10:07:53 GMT -8
Max, These dimensions are correct for a 6 incher. The channel plate higher and wider than the tube will result in a more or less independent draft. Try with some smoke or a cigarette lighter whether it's drafting or not. When the thing is lit, at first there's nothing to distinguish it from a stove without this. After some time you will notice there's less smoke, even at start up. It will make the stove work better at lower temps, among other things.
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Post by satamax on Sept 25, 2012 10:52:48 GMT -8
I've tried 5mm gap, on the hot stove, ney workey either. Anyway, this thing is temperamental. I can't use it, when hot with the full feed tube opening. I have to put a brick on it edge above the feed tube to avoid the occasional puff of smoke. But that makes a kind of P chanel, as the burn tunel side of the feed tube is rounded. The brick lying against the edge of the gas bottle, i have two holes either side, at the back. I gonna try a proper P chanel when i find a suitable piece of metal.
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Post by peterberg on Sept 25, 2012 11:32:18 GMT -8
Oh yes, of course, you've got a 6" system and a 4.5" exhaust or something like that. That could be the underlying problem of not being able to run the hot stove without blocking the feed tube partly. Never mind, this p-channel is a gadget which will transform a critical stove in an even more stubborn horse, I'm afraid.
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Post by satamax on Sept 25, 2012 11:39:02 GMT -8
Yep Peter. But that one, is impossible to override, the flue hole in the 60cm wall is gonna stay as it is. Thought i could go up to the wall in 153mm, and after the brick chimney is 14x20cm. That would make only a venturi. Not being smaller all the way!
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Post by daniel on Aug 22, 2015 14:01:13 GMT -8
Hi,
I would like to ask if after the inlet into the bell the opening must become much wider than the inlet and if so by how much, also I was thinking about using rocks supported somehow above the inlet inside the bell to absorb heat having a higher surface area than the simple bell. Would the heat travel around the stones if they are round and pretty large?
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Post by peterberg on Aug 24, 2015 8:04:06 GMT -8
The bell need to be much wider than the inlet, about 4 or 5 times as a minimum, depending on the quality of the chimney stack, but the more the better.
Yes, what you suggest is indeed a way to enlarge the ISA of the bell. Imagine one which sports a footprint like a giant letter E, that would be a much larger wall surface combined with a relatively small volume.
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Post by daniel on Aug 24, 2015 12:35:41 GMT -8
Thank you,
Is the width of the bell immediately after the opening important to be wider 4 to 5 times or just the CSA of the bell should be be 4 to 5 times more than the opening area? My first bell will be above the riser 1-3 ft, the second it will next to it but I have to figure out what is best CSA shape for the cooled gases to travel ( meander or straight). Now I am very inclined to build the bells out of protruding stones layered with refractory mortar. I have to find out the best possible heat retaining stone for the upper part and perhaps something more insulating for the bottom.
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