Frank Blaker

Thank you for the link Joe,
I can see so much solved in the food drier, and so much careful research there. I think I need to go down the route of a loose laid brick mass for a rocket mass heater, this is to make the kiln transportable and for the experimental period adjustable. If I lay the bricks looser at the edge as to encourage air channels to pick up heat and take it into the kiln, micro adjust the air channels to allow for heat collecting sooner nearer the burner and use slab wood louvres to form the kiln walls, combine this with a double wall chimney to vacuum wet air out of the kiln. And a steeply sloped tarp roof to allow condensate to drip outwards I may have a design.
I live in a hilly region and woodlands tend to be on slopes as this intensively farmed country has most flatland cleared for agriculture. I'm thinking I could build the rocket on a slope so the insulated riser feeds straight into the mass, allow for a high temperature at this point in the mass by creating a double floor with scrap steel plate, and have an extra large firebox to allow for less frequent stoking. Maybe being on a slope so the heated air doesn't have travel down inside an old barrel will mean the rocket doesn't need the energy to push the gases through so much.
Thanks again for the link, any further thoughts are very much appreciated.

Frank

Thanks joe, really useful.

Regards

Frank

Thanks for the thoughts. How did the vermiculite board fare? It looks like a good riser.

Regards


Frank

Hi,
I use metal straps to reinforce loose laid bricks in kiln building, where thermal ranges cause a lot of movement in the structure. I wondered if wire to reinforce at hot spot to colder spot transition points would ease the possible problems of cracks. I totaly take the point about condensation, maybe warm cob can assimilate it, transfer it to the surface and dry it out through evaporation. Kiko Denzer advises that a clay oven can do this when moisture from food being cooked can threaten to soften an adobe oven roof. I saw so many possibilities for smooth rounded cob shapes in your idea that left me thinking, any arch other than a catenary arch puts outward pressure on its supporting walls, so some sort of bracing pulling the walls inwards can be needed in a minimal structure. I also got to reading ianto Evans book where he says the square corners help promote turbulance, aiding the mix of oxygen and hot unburnt gas. This seems to say the blocky, corbelled roof is better than rounded or arched shapes.
I love the idea of cob blocks as I find I can think designs through when I can play in 3d.
Would you use clay and sawdust or perlite mixes for some of the blocks? What would you think of blocks with a layer of this mix say 2 inches thick added at the block making stage?

Love the photos, thanks for sharing them. I live in the uk where cob buildings go back to the seventh century still partly stand. I do some cob repair work and one technique is to bury steel wire in channels cut under the surface of the cob. If your stove shrinks and cracks, do you intend to fill the cracks, leave them to open and close as heat dictates or fill and stitch across them? I love the idea of cob blocks to build a stove, particularly as you can corbel them. Did you think maybe you could build an arch or use a former left inside to burn away? Thanks again for sharing those photos, really interesting.

I am aiming to build a firewood drier using a rocket mass heater floor, slab wood walls and a tarp roof. I have seen a shipping container and biomass boiler combo advertised that claims to get fresh cut ash down to 20% in a seven day period. I would see this high tech biomass stove and steel container as the commercial end of a spectrum. I would like to operate at the bottom end of the spectrum and develop, then share a design to dry timber in a week for the price of sustainably sourced, low cost and reclaimed material. Anyone out there got thoughts on the science here?
We operate a mobile sawmill and forestry team and would like to enable small landowners to use waste wood to dry firewood they can then sell. If promoting rocket mass heat technology can come into the scenario so much the better.
I currently have a feeling that a pair of rocket stoves using 55 gallon steel drums over firebrick risers will be worth attempting to heat and dry four cords at a time. I also think an air permeable mass using loose piled brick an d gravel in a timber box with air intakes at the bottom may be the best way to use the rockets to create a warm dry air flow over the firewood grain ends.
All thoughts are welcome on this one. I hope to solve the problems to the point of an experimental structure by mid December.