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Post by coisinger on Jun 21, 2016 8:43:24 GMT -8
It seems to me that a cast riser core is pretty much a no brainer, but what about casting the outer casing as well?
I understand that heat radiation would be limited until the entire core and outer casing came to temperature. It would likely slow the function of the heater as well, as there would be no metal to get 'hot' and create draft. There has to be heat to create a draw, yet if made lightweight using perlite, or another light-weight high-heat capable material, and refractory it could be made in a couple sections over the riser, similar to the bell of a concrete drainage pipe, allowing for disassembly and inspection. With that in mind, I'd consider casting the top of the outer casing as well.
I am interested more in this approach for a bench mass heater and/or a stove/oven design as opposed to an area heater.
Has anyone tried this approach?
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Post by Deleted on Jun 21, 2016 10:05:25 GMT -8
Some minerals have in high purity a higher thermal conductivity than many kinds of steel.
Thermal conductivity in W/(m K). Steel, Carbon 1% 43 Stainless Steel 16 Aluminum Oxide 30 Silicon carbide 360-490 As Bulk SiC 100-350
Just add a lot Aluminum Oxide or Silicon carbide to your mixture to raise thermal conductivity. To get in the range of Stainless Steel is not a big deal. There are some scientific papers dealing with the best particle size distribution to achive maximal conductivity.
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Post by coisinger on Jun 23, 2016 10:04:38 GMT -8
Silicon Carbide, blasting agent, is relatively cheap. It's thermal properties are well suited for the application as it's used in semiconductor furnaces. Aluminum Oxide is "angular". A mixture of the two at 80 grit would be a nice aggregate base with some perlite as well.
Now I will have to research the proper ratios to get my desired results!
Thank you sir.
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Post by coisinger on Jul 13, 2016 3:13:23 GMT -8
Still in the research phase, but I am considering an all cast core, riser and 'barrel'. My casting mixes will be different for all parts and I plan on adding additional Aluminum Oxide and/or Silicon Carbide to my refractory mix for the barrel portion so it can radiate some of that heat as opposed to insulating it.
While on my sketchpad, I was coming up with ideas for the top of the barrel. I've not seen it used regularly, but why not bell the top of the heat exchanger? Instead of the swirling hot gases blasting directly at a flat surface, it seems to make more sense to give them a path where they can rotate down around the riser. (Note to self: I need to be able to post photos somewhere.)
Oh and as an aside: Quick-crete tube forms in 8" and 12" diameter will make the perfect riser with 2" of material all around. (about $15 at the local big box hardware store).
Anyways, thanks for the great site and all the input which I am devouring.
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Post by coisinger on Aug 16, 2016 9:31:53 GMT -8
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Post by Deleted on Aug 16, 2016 11:42:31 GMT -8
The links do not work.
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Post by coisinger on Aug 17, 2016 8:32:20 GMT -8
Fixed the links...
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Post by Deleted on Aug 17, 2016 8:46:02 GMT -8
Still 404
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Post by satamax on Aug 17, 2016 11:57:25 GMT -8
They're private, not public!
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Post by coisinger on Aug 19, 2016 3:18:05 GMT -8
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Post by Deleted on Aug 19, 2016 5:10:50 GMT -8
This link works.
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Post by SteveStuff on Mar 9, 2017 16:50:16 GMT -8
Ok so this thread went dead?
First... what is the intention of the port going back down into the top of the firebox just a glass "window" as described?
Second... Have you gotten around to doing this? Extremely curious about any results. Wondering how Monolithic bells will perform with such temperature differentials from top to bottom and not crack.
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Post by SteveStuff on Mar 9, 2017 16:53:47 GMT -8
By the way, like the step by step sketchup pics. Easy to see the idea.
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