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Post by patamos on Mar 20, 2015 15:28:02 GMT -8
Thanks Benoit, Ah yes, the dry joint. I remember thinking how it might the useful in some designs but not others. Those diagrams are very interesting. Especially the ones showing how the shape of the bell exit can determine how much is pulled from where. Wish i could read Russian!! I have a feeling it would be difficult to achieve even division of gasses around a column. As surely as water will not flow in a straight line, one side will be more attractive for some reason(s) or another and will evoke a current that will amplify itself. This might even change from side to side depending on rate of combustion and gas movement. Perhaps the difference will not be very much… I am now thinking of diagonal columns to coax the gases towards the front wall of the bell where i want more heat to radiate… This is so interesting Thanks for Sharing
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Post by satamax on Mar 21, 2015 0:26:42 GMT -8
Hi everybody. Well, there's a few things which i think are important. Lengh of the bell, to slow down that jet effect, so gases have time to rise. I don't know about the width, because the drag created by the walls, might slow down that jet effect, but also it can impede with the rise of the gases. One thing i'm kind of sure of, the volume of the bell. Bell has to have a certain internal surface area, but also a certain volume, for the gases to stratify in there. Best ratio is volume to surface is a cylinder. But it lacks lengh. That's prety much all i understand about bells
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Post by pyrophile on Mar 22, 2015 4:44:41 GMT -8
I go on questionning bells... The second bell of our stoves is typically a bell because both entry and exit of the gases to be cooled are at the lower part of the bell. I have the impression that, if the bell is empty (without columns or baffle), gases that are slowm down by bell's big volume take time to stratify whereas, in the same time, they are also going towrds the exit. This horizontal movement may concentrate the biggest proportion of hot gases in the middle of the bell, in its upper part instead of an uniform concentration. I mean that most of hot gases don't rise immediatly in the first portion of the bell. Of course, a little part does! But I think that most of hot gases, because of the combination of both forces present in the bell (a vertical -up- force caused by difference of temperatures and an horizontal and vertical -down- force caused by draft towards the bottom and towards the other end of the bell) do concentrate hot gases in the middle (and upper part) of the bell. Then, I think that a column placed at the beginning of the bell (like above in Chervov's second bell) has an effect on stratification. It helps it for a quicker and stronger stratification. This column makes of course the way longer (in time and space) to gases but maybe it also creates a kind of false or quasi little bell. I have the impression that the space beetween two column creates a simili bell's effect. May I be totally dreaming? (it is possible!!) Benoit
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Post by pyrophile on Mar 22, 2015 8:37:27 GMT -8
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Post by peterberg on Mar 23, 2015 3:21:09 GMT -8
I have the impression that the space beetween two column creates a simili bell's effect. May I be totally dreaming? In my opinion, you are not. In a true bell the gases stream into the space, rising gradually as they go forward. At some point the gases reaching the opposite wall, spreading out and up and curling back. When you place an obstacle in the stream trajectory, like a column, the curling up should take place earlier. Not the whole of the gas volume because part of it will stream around the object. In other words, objects like columns will distribute the gases more evenly through the bell as a whole. So, building columns in a bell could help to heat the bell more uniform, adding mass and internal surface area at the same time. All the above is my two cents.
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Post by patamos on Mar 23, 2015 21:19:16 GMT -8
Here is a variant of a Vortex style heater i am working on. Downdraft is to the left of the firebox. The first bell is left of that under a sitting bench with the exit at far left. The second bell will be tall and narrow behind the bench up a 6" wide cavity behind the backrest. I have loose stacked 4 clay bricks to serve as a column where i think they will be most effective. But this is only a wild guess. The good news is, my clean-out (under left side wall) is close enough that i will be able to reach in and move the column around to see what happens. Any other ideas are most welcome...
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Post by Robert on Mar 24, 2015 3:09:00 GMT -8
patamos interesting firebox, can you please tell some more details? and maybe you are sharing your pictures in another thread?
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Post by patamos on Mar 24, 2015 8:51:29 GMT -8
Hi Robert, I have been waiting to write about this build til i have the official 'written' approval of the local building inspector (a very decent fellow by the way). I received a verbal 'yes' a month ago and started building but then opted to stop until all the formal details are sorted out. Hopefully this will happen when he visits later today I will post more details over at 'vortex' thread soon.
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Post by pyrophile on Mar 24, 2015 13:00:32 GMT -8
I would add that I have the impression that columns must let only small space beetween them and bell's walls. Otherwise they don't work as well. But what is "small space"? I think that 10 cm is too much. Could we suppose that the narrower space (5cm or less?) the more bell effect? As long as the space between bell's walls and column is much bigger than output area, it should work! But one could say that it is less and less a bell's effect!
Benoit
PS : All that I wrote on this thread concerns masonry bells.
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Post by pyrophile on Mar 25, 2015 0:48:10 GMT -8
Here is an exchanger (the third one) which corresponds to what Grum Gzrimailo considers as a way to get equal division of hot gases among all columns : This kind of exchanger appears regularely in russian books or other documents one can find. Benoit PS : Wahoo! I succeeded to put an image! The problem is to remember...I should!
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Post by pyrophile on Mar 25, 2015 1:45:25 GMT -8
Here is, i suppose, an explanation on Grum Grzimailo's bell where bricks are in star shape, acting as columns : Any translator? That would be nice! But some job... When printed, you can read it. It comes from the russian forum stovemaster.ru (in good terms with I. Kuznetsov). Benoit
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Post by pyrophile on Mar 25, 2015 1:56:43 GMT -8
Here is a multiple bells stove! Benoit
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Post by patamos on Mar 29, 2015 8:37:33 GMT -8
Looking at those designs, one issue that comes to mind is clean outs. Here in the wet west coast of Canada people sometimes burn wet wood no matter how much they know they shouldn't. So in the early stages of a burn the crystalline creosote likes to clog up channels...
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Post by pyrophile on Mar 30, 2015 9:40:05 GMT -8
Clean outs are easy to install but cleaning could be difficult, above all with wet wood! I have the impression that when people fully pay their mass stove, they take care to have dry wood. With friends who don't pay, they often don't care!
Benoit
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Post by patamos on Apr 1, 2015 9:22:45 GMT -8
Ya that is often true.
And then there are times where people are just stuck. In one house we built the masonry heater as we built the house and then needed it to warm and dry all the clay-mud work… With all the busyness of the building project the owner only had green douglas fir to burn so that is what he used. When i cleaned out the 4 flue runs the following year, the lower (first) two had lots of web-like creosote build up, especially in the corners of turns. So that got me to realizing that no matter how hot the fire eventually gets, during warm up the wet wood will make for nasty deposits. In a way, this is more of a problem with lengthy high mass flue runs because it is very difficult to crank the heat up and clear out the deposits like one can with an insulated metal flue. A relatively minor drawback of course, but a drawback nonetheless. With this in mind, the simpler hollow bell with easy to clean columns and baffles etc... is appealing.
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