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Post by canyon on Jan 25, 2009 11:03:29 GMT -8
This is such an intriguing subject that I can't help but continue to ponder. I am currently dreaming about a single bell after a heat riser built as a baking oven with a door. This to me seems like a good multiple use kind of thing since my more permanent rocket will be in my kitchen. After a firing there would be the option of opening the door and baking bread or pizza! Also, this concept of small precast ceramic mini bells (that perhaps could key together) for a subsequent bench has my dreaming mind going as well. Up till now I had intended to bury an approximately 27 foot flue in a bench with a ss sheet metal turbulator to break up the laminar flow that Peterberg mentions. The turbulator(common in fire tube boilers) is just a long piece of sheet sheared to a little less than the flue diameter and given a twist (spiraled). But this free air concept of the series of bells allowing the cooler ballast gasses to pass quicker and the hotter gasses to give up their heat to the bell tops is interesting. Potential issues with the bell idea could include hot spots on the bench and perhaps too high a bench for comfortable seating. Since I'm still too far behind on my overall project to try out these ideas I'l just keep dreaming...
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Post by Donkey on Jan 25, 2009 13:49:54 GMT -8
I've been thinking on this one too.. The bell concept is a pretty exciting idea. I've been thinking about the oven concept as well. I'd build a cob oven, beehive style, with the rocket under. It would need to vent below to work properly.. Possibly a combo exhaust/ash drop or something.
Seems that laminar flow early on in a bench is a good thing.. It tends to get too hot right next to the stove anyway. Some kind of turbulator (I like the word) should then probably be used a little downstream. Perhaps this could even the temps down the run somewhat.
With a little planning ahead, if built into an earthen or concrete slab floor, a bell-type bench could be sunk into the ground. I'd hate to do that modification afterward though.
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Post by peterberg on Jan 28, 2009 11:44:27 GMT -8
...But this free air concept of the series of bells allowing the cooler ballast gasses to pass quicker and the hotter gasses to give up their heat to the bell tops is interesting. Potential issues with the bell idea could include hot spots on the bench and perhaps too high a bench for comfortable seating. Canyon, Perhaps in 2 months time, there will be more to know about bells and benches. I am working on a design of a bell with a new idea about a firebox inside and a different rocket siphon. To take up most of the heat I am planning to build a bench, divided in two further bells. One for the seat, the other for the back rest. Nothing fancy, probably ugly, will not last long, only to find out whether this will work or not. The three bells together will not be larger in cubic feet than the earlier iterations. But with quite a bit more wall area. A bypass damper will be absolutely necessary.
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Post by Donkey on Jan 28, 2009 16:31:58 GMT -8
The bypass damper is for the purpose of heating the chimney for startup??
If so you could install a primer box, which is just a small chamber with a hatch below the chimney. A handful of burning phonebook in the hatch usually does the trick. Though access to the box becomes an issue. It should be easy to get at and convenient to use.
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Post by canyon on Jan 28, 2009 23:40:33 GMT -8
Donkey, good point on placing the turbulator downstream a little. Makes total sense. Peterberg, I have been trying to figure out what to use for bypass dampers that can stand up to the stresses. The best I've come up with is to make a Y style diverter valve but with mostly hard firebrick. What are you experienced with? I am excited to hear that you have a bell bench on the drawing board.
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Post by peterberg on Jan 29, 2009 9:46:51 GMT -8
The bypass damper is for the purpose of heating the chimney for startup?? I'll rephrase that. (In the new bell system on my drawing board) A bypass damper or primer box is absolutely necessary. And to canyon: for a bypass, I'll try to avoid the hottest spot of the whole contraption like the plague. In other words, the best place for a damper is at the bottom of the first bell. Or where the gases are streaming from the barrel into the bench. See picasaweb.google.com/eritter/RocketStoveDecember2007#, that one is ideally suited for a bypass, because the chimney is situated right beside the barrel. A really nice one, Ernie!
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