derek
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Posts: 14 
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Post by derek on Feb 10, 2016 1:36:54 GMT -8
I'm curious,
Is the fire box and heat riser required to store any heat in order to facilitate optimal burning? If a new super styrofoam capable of withstanding 5000 °C were available, would it be a good material?
Or is thermal mass inside the chambers needed to accumulate heat?
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Post by peterberg on Feb 10, 2016 3:51:41 GMT -8
The less mass in the combustion core, the earlier it is up to high temperature an clean burning. But the material in the firebox need to be abrasive-resistant, so foam isn't good in that respect.
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Post by pinhead on Feb 10, 2016 8:01:25 GMT -8
The "perfect" material would be hard enough to withstand abrasion, super-insulative with low mass and able to withstand high temperatures, and highly reflective to reflect radiant heat back into the fuel. This would be for both the core and the heat riser, though the heat riser doesn't need to be as hard/strong.
EDIT: As far as I'm concerned, we already have the perfect material for the heat riser: ceramic fiber.
The one thing I'd like to experiment with is wrapping the ceramic-fiber riser with a radiant barrier. I don't think aluminum radiant barrier would be able to withstand the temperatures inside a proper stove with barrel and all, though it might hold up to a "bare core" for testing. Polished stainless steel would probably work as well and be able to withstand higher temperatures.
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derek
New Member
Posts: 14
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Post by derek on Feb 10, 2016 9:54:53 GMT -8
The less mass in the combustion core, the earlier it is up to high temperature an clean burning. But the material in the firebox need to be abrasive-resistant, so foam isn't good in that respect. "foam" was a hypothetical! i.e., a material with negligable mass to store heat and super insulating. |
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Post by briank on Feb 10, 2016 9:59:01 GMT -8
The "perfect" material would be hard enough to withstand abrasion, super-insulative with low mass and able to withstand high temperatures, and highly reflective to reflect radiant heat back into the fuel. This would be for both the core and the heat riser, though the heat riser doesn't need to be as hard/strong. EDIT: As far as I'm concerned, we already have the perfect material for the heat riser: ceramic fiber. The one thing I'd like to experiment with is wrapping the ceramic-fiber riser with a radiant barrier. I don't think aluminum radiant barrier would be able to withstand the temperatures inside a proper stove with barrel and all, though it might hold up to a "bare core" for testing. Polished stainless steel would probably work as well and be able to withstand higher temperatures. I'm waiting on prices for a vacuum formed ceramic fiber batch box, made in two parts with a P channel. It would be formed to allow lining the bottom, sides and rear with half thickness firebrick. My only concern is whether it could withstand the compression from the weight of the firebricks and a load of firewood. Thoughts? |
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Post by pinhead on Feb 10, 2016 12:37:10 GMT -8
The "perfect" material would be hard enough to withstand abrasion, super-insulative with low mass and able to withstand high temperatures, and highly reflective to reflect radiant heat back into the fuel. This would be for both the core and the heat riser, though the heat riser doesn't need to be as hard/strong. EDIT: As far as I'm concerned, we already have the perfect material for the heat riser: ceramic fiber. The one thing I'd like to experiment with is wrapping the ceramic-fiber riser with a radiant barrier. I don't think aluminum radiant barrier would be able to withstand the temperatures inside a proper stove with barrel and all, though it might hold up to a "bare core" for testing. Polished stainless steel would probably work as well and be able to withstand higher temperatures. I'm waiting on prices for a vacuum formed ceramic fiber batch box, made in two parts with a P channel. It would be formed to allow lining the bottom, sides and rear with half thickness firebrick. My only concern is whether it could withstand the compression from the weight of the firebricks and a load of firewood. Thoughts? I've followed that thread fairly closely. It all depends on the strength of the binder, I suppose. If firebrick splits are used on the floor of the box, they could set on top of a thin sheet of steel to spread the load. If the material compresses too much to provide insulation on the bottom of the box, it would be fairly simple to support the entire assembly at the perimeter and add more (cheaper) insulation beneath. I envision a ceramic-fiber batch box sitting atop a flat sheet of metal, supported on the edges or corners, with another layer of insulation beneath the assembly. Since the metal would be protected by both firebrick and ceramic-fiber insulation, mild steel will easily do the job - and will evenly spread the weight of the brick and fuel. |
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Post by briank on Feb 10, 2016 13:23:01 GMT -8
I've followed that thread fairly closely. It all depends on the strength of the binder, I suppose. If firebrick splits are used on the floor of the box, they could set on top of a thin sheet of steel to spread the load. If the material compresses too much to provide insulation on the bottom of the box, it would be fairly simple to support the entire assembly at the perimeter and add more (cheaper) insulation beneath. I envision a ceramic-fiber batch box sitting atop a flat sheet of metal, supported on the edges or corners, with another layer of insulation beneath the assembly. Since the metal would be protected by both firebrick and ceramic-fiber insulation, mild steel will easily do the job - and will evenly spread the weight of the brick and fuel. I think if the batch box is just a simple rectangular box externally it will be easy to wrap with a steel box around it for support, which in turn could help support the barrel. I was also thinking of lining the area internally under the firebricks with stainless steel to distribute the weight of the firebricks and firewood. Also, they could make a hard one piece cast refractory liner for it, eliminating the firebrick and metal liner. That would increase price but they already manufacture similar items for the foundry industry in the area and they could be off the shelf replacement items if the liner eventually wears out. |
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Post by pinhead on Feb 10, 2016 13:54:40 GMT -8
Also, they could make a hard one piece cast refractory liner for it, eliminating the firebrick and metal liner. That would increase price but they already manufacture similar items for the foundry industry in the area and they could be off the shelf replacement items if the liner eventually wears out. If they build a one-piece cast refractory liner, the ceramic-fiber wouldn't need any hardener and could simply "wrap" the firebox much like Peterberg does with his stoves. At that point, the only thing that would need to be formed is the heat riser. |
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Deleted
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Post by Deleted on Feb 11, 2016 5:17:24 GMT -8
A mineral airgel could still have a density around 1.5.
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Post by briank on Feb 11, 2016 8:13:31 GMT -8
I heard back from the sales rep at Temtek, they are looking at the batch box files and I should have a rough estimate on a price for a 2 piece vacuum formed ceramic fiber batch box within the next week or two. Initially we're looking at simply lining with half thickness firebrick. That will likely be the cheapest and easiest option to get these out there for testing/experimentation.
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Post by briank on Feb 13, 2016 22:10:11 GMT -8
If they build a one-piece cast refractory liner, the ceramic-fiber wouldn't need any hardener and could simply "wrap" the firebox much like Peterberg does with his stoves. At that point, the only thing that would need to be formed is the heat riser. There's a spray on ceramic chimney liner called Thermocrete: ventechindustries.com/products/thermocrete/They claim a service temp of 2900*F and that it's very hard, abrasion resistant, it strengthens the chimney structure and the chimney can subsequently be cleaned by metal brush. It's also a relatively thin layer and supposedly does not decrease the internal diameter of the chimney. I wonder if the inside of a vacuum formed ceramic fiber batch box were sprayed with Thermocrete if it would hold up to loading and burning with firewood. That would eliminate the need for a split firebrick liner. Maybe a light gauge stainless liner under the Thermocrete to distribute weight on the bottom, sides and rear? We have a local chimney sweep certified in applying Thermocrete. It might well be worth experimenting with it. |
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derek
New Member
Posts: 14
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Post by derek on Feb 14, 2016 9:46:35 GMT -8
If they build a one-piece cast refractory liner, the ceramic-fiber wouldn't need any hardener and could simply "wrap" the firebox much like Peterberg does with his stoves. At that point, the only thing that would need to be formed is the heat riser. There's a spray on ceramic chimney liner called Thermocrete: ventechindustries.com/products/thermocrete/They claim a service temp of 2900*F and that it's very hard, abrasion resistant, it strengthens the chimney structure and the chimney can subsequently be cleaned by metal brush. It's also a relatively thin layer and supposedly does not decrease the internal diameter of the chimney. I wonder if the inside of a vacuum formed ceramic fiber batch box were sprayed with Thermocrete if it would hold up to loading and burning with firewood. That would eliminate the need for a split firebrick liner. Maybe a light gauge stainless liner under the Thermocrete to distribute weight on the bottom, sides and rear? We have a local chimney sweep certified in applying Thermocrete. It might well be worth experimenting with it. I've been wondering about ceramic chimney liner "cement" too. In Scandinavia, this is common chimney renovation. The "cement" is poured into the chimney and then a rubber plug is pulled up through the mix leaving a round hole. Another method uses a long rubber sausage which is inflated with air to form the hole. I believe it is rated to 1000°C. |
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dino
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Post by dino on Feb 14, 2016 11:09:18 GMT -8
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Post by philippeelskens on Feb 16, 2016 13:02:32 GMT -8
When I started my design, I very quickly settled on perlite clay (for the riser, still unsure about the primary burner...). Good insulation, cheap...
However, it seems almost no one ever mentions perlite, so I'm starting to think it has downsides I'm missing...?
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Post by pinhead on Feb 16, 2016 13:06:45 GMT -8
When I started my design, I very quickly settled on perlite clay (for the riser, still unsure about the primary burner...). Good insulation, cheap... However, it seems almost no one ever mentions perlite, so I'm starting to think it has downsides I'm missing...? It's not often mentioned because it's often assumed. I made my riser out of clay-perlite and it's working perfectly after over a year so far. |
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