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Post by satamax on Nov 7, 2014 21:46:08 GMT -8
Hi everybody.
Well, early morn here. And i have a buzzy head!
I am under the impression that we're going the wrong way about usual rockets's heat storage.
Basicaly, the gases right out of the heat riser are realy hot. And the barrel sheds a lot of heat quickly into a room, untill it's unberable if you burn the stove for too long.
Then most of the people use a solid mass to gather the residual heat which hasn't been released by the "radiator"
But, wait a min, doesn't that mass cope with far higher temps than what exhausts the barrel?
Matthew had already said he's using a little metallic barrel bell at the end of some systems go gather the last heat.
Wouldn't it be cleverer, to store the high heat right out of the heat riser into the mass directly, and then use the residual heat to warm the room? With a metallic bell?
Well, seeya!
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Post by Daryl on Nov 8, 2014 2:30:11 GMT -8
Why metal? Metal doesn't store the heat very well. Why not empty the rocket into full mass like the oven systems? Skip the radiator.
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Post by satamax on Nov 8, 2014 3:22:23 GMT -8
Why metal? Metal doesn't store the heat very well. Why not empty the rocket into full mass like the oven systems? Skip the radiator. Well, that can be done too. I didn't explain too well. The idea is to make a high mass bell first inline of the heat riser, to get the blast of realy hot gases, then following that a little metal bell radiator to warm up the room faster. When it's the coldest. Usualy people burn wood in the evening, when the temp drops. So that would be convenient, to not shed as much heat into the room, and charge the mass for a longer period, by using the residual heat to heat the room, not the main heat. Well, it's not very clear hey? There would be a side effect with that, for people wanting to keep the barrel or metallic bell. The draft going through the first bell, , which warms up at the contact of the mass would be then cooled a smidge better by the metallic bell, than if left alone to go in the flue/chimney. Or may be i'm just barking mad
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Post by Daryl on Nov 8, 2014 3:57:04 GMT -8
The idea is to make a high mass bell first inline of the heat riser, to get the blast of realy hot gases, then following that a little metal bell radiator to warm up the room faster. Ditch the drum and add a mini one at the end. Good idea.
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Post by PNW Dave on Nov 8, 2014 4:39:13 GMT -8
Isn't that initial quick shedding of heat somewhat necessary for the downdraft that occurs immediately after the riser? In reading other discussions, I recall people mentioning that cobbing over the entire barrel negatively effects draft because it holds in too much heat and the temperature difference between inside the riser and outside the riser gets too close to equalizing.
I think what you are saying is, similar to Peters method of a second barrel stacked on top (so there is a riser-to-barrel top gap of 1 barrel plus 3"), it could be built out of bricks or cob instead of barrels. Maybe the extra space and somewhat bell-like performance would allow sufficient cooling of the gasses, while providing lots of mass around the hottest gasses. Then I imagine running the exhaust through a half-barrel bell-bench and finally a barrel for quickly radiating the last bit of heat. Maybe the gasses would be cooled too much to rise out the final chimney though.
Or maybe you have a different design in mind, which doesn't use the standard heat riser and immediate down draft?
In the design of my build in progress, I'm adding a second larger barrel (55 gal) over the main barrel (30 gal), which I'll connect the chimney to. Passing the exhaust through the space between the two barrels to be reheated and improve draft. The half barrel bench being 6-8 half barrels with seating for 6 plus a daybed for two. Even though it is a dead end type bell, I think the increase in draft will be significant and needed, plus I'm not particularly interested in any of the radiant heat from the first barrel in my application.
My point being that maybe in other applications, adding the second barrel to reheat the exhaust could help pull through much larger masses with longer runs and more elbows. This could extract "too much" heat from the gasses, but it's OK because it will be significantly reheated before exiting. While also reducing the immediate heat released into the room. If the loss of heat by reheating the exhaust on its way out the chimney, is made up for with more storage in a bigger flywheel, it might be worth it.
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Post by Daryl on Nov 8, 2014 5:42:09 GMT -8
The barrel pushes the gases into the bench mass. If I understand Max's design, there won't be a need for the bench. It will be basically a pure masonry stove with a rocket core and a small barrel radiator at the end. Max's stove will be a much smaller design so the draft shouldn't be so drastically effected. Instead of heating two masses (the cobbed barrel and bench), there will only be one mass.
Vortex, Peter, and Dragon Heaters have already built similar masonry designs with no barrel needed.
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Post by satamax on Nov 8, 2014 8:33:53 GMT -8
Well, i don't realy believe about that downdraft created by the barrel. May be it has some effect, but i would like to see it measured.
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Post by ronyon on Nov 8, 2014 10:33:29 GMT -8
How about just a metal plate radiator? Build it into the side of the masonry bell, perhaps at the base so only the lowest temperature gasses would be in contact with it. Maybe leave the end of a half drum bench uncovered.
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Post by satamax on Nov 8, 2014 19:58:46 GMT -8
How about just a metal plate radiator? Build it into the side of the masonry bell, perhaps at the base so only the lowest temperature gasses would be in contact with it. Maybe leave the end of a half drum bench uncovered. Well, i already thought about that. The first mention about it might even be in the horizontal rocket thread. Latest one donkey32.proboards.com/post/14038/threadAs i was implying there. A closet made out of bricks, with a metal door. And a rocket on one side. Hard to keep airtight. But could be done. But it's not my point here. The thing is that my gut feeling tells me the barrel is just on the wrong end on "normal" rockets The mass could be heated far more if hit directly by high temps, and charge far more. Thus, enabling more long term storage. Well, it's about fiveish here, so in my sleeping period, been awake since three thirty, and i'm babling away talking senseless!
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Post by patamos on Nov 8, 2014 21:40:46 GMT -8
Non-barrel downdraft worked fine in this case donkey32.proboards.com/thread/1065/non-metal-barrel-downdraft-chambersI had over 20 feet of stack height and a start up bypass flue to play with, so those factors probably helped. But my sense is that optimizing gas flow with appropriate channel sizing relative to directional shifts and the effect of boundary layers... is probably the main difference between things working well or not. Every part of the heater except the griddle top is touchable after a full day firing. Some areas hotter sooner than others. Some warmer longer. The variation was partly accidental resulting from an attempt to combine flue runs with bell chambers in the bench. But the clients like the range of warming options. I guess it all depends on when you want the heat and where. You could even go with a full masonry bell and have the exit flue be uninsulated til near ceiling. Perhaps it could even be widened out to double (or so) the diameter of the system size and re-narrowed at the 7 ft height to let the gasses mingle a little longer below the bottleneck. This would send the mild to moderate radiant heat in very useful directions,
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Post by PNW Dave on Nov 9, 2014 0:24:49 GMT -8
Well, i don't realy believe about that downdraft created by the barrel. May be it has some effect, but i would like to see it measured. Well, now I want to see it measured too! I can envision the physics of the downdraft theory but whether it has as significant of an effect as it has been made out to be? I don't know... ...to not shed as much heat into the room, and charge the mass for a longer period, by using the residual heat to heat the room, not the main heat. Sounds logical. Pretty sure I have a good understanding of your idea and I think it is a good one! On really cold days when I run my wood stove insert hard, it can get warmer than I'd like in the main living area but you can be sure that it won't last overnight. Man do I ever want to do an RMH conversion!
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