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Post by chrish1978 on Nov 12, 2017 8:39:23 GMT -8
Hi guys
I'm pretty new to the rocket stove game, but finding myself obsessing about them since discovering through complete accident on YouTube.
I loved the simplicity of them and have thus far created a few different designs, albeit on a very small scale with some success!
I then thought why not give a RMH a go?!
So I've set about planning,drawing and losing sleep in equal measure and have almost fabricated and welded my first ever RMH. My girlfriend thinks I'm crazy, but hey-horses for courses!
Anyway please visit my video on YouTube where I walk through my design on CAD to give you an idea of what I will be finally calling the finished article..
I'm a welder/plater by trade with access to plenty of materials, so fingers crossed when she gets fired up for the first time, she will rocket!
I will be posting another video shortly with my project from start to finish, including the first fire up, so stay tuned.
Peace
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Post by drooster on Nov 12, 2017 9:16:23 GMT -8
... I'm a welder/plater by trade with access to plenty of materials, ... By materials I guess you mainly mean ... metal?
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Post by chrish1978 on Nov 12, 2017 9:48:26 GMT -8
Yup, metals mainly low carbon steel of various wall thicknesses my friend
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Post by Orange on Nov 12, 2017 11:57:31 GMT -8
we say "matal is doomed" because it starts peeling from inside.
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Post by pinhead on Nov 13, 2017 8:35:23 GMT -8
It's not a proper rocket if the flame path isn't insulated.
There isn't a metal in existence that can withstand the rigors of a properly running rocket stove. The low carbon, high oxygen environment in combination with high temperature will pull the carbon directly out of the metal, causing spalling and eventual failure. The steel will basically flake off as slag. As Orange said, metal is doomed.
Forget everything you've learned on Youtube; with regards to rocket stoves, 99% of it is garbage.
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Post by drooster on Nov 13, 2017 10:46:11 GMT -8
Chrish I'm afraid this particular forum is biased away from steel rocket construction simply because some researchers here have developed the rocket-mechanism so far that temperatures in their units exceed that which most steels can withstand. The higher the temperature the more efficient the complete burn of wood-gases. An all-iron rocket is disparaged on this forum because it is unable to reach high enough temperatures inside the riser : i.e. not high enough to be respected. If you persevere and include refractory ceramics in your riser section you are in the right place to get great information.
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Post by coastalrocketeer on Nov 23, 2017 15:03:57 GMT -8
You can certainly use steel for non "hot-zone" flame path areas...
The biggest key besides good design/dimensioning for gas flow and turbulence with proper excess air in the "hot zone" is a high temperature, highly INSULATIVE refractory material for the "riser and burn tunnel" inner faces. Low mass insulative refractory is not absolutely necessary, but preferred because it gets up to "high efficiency, extreme temperature" combustion faster.
As the outer cladding on that "hot zone", with sufficiently insulative inner face, metal certainly CAN survive.
Basically, anyone achieving the desired high temps will not have a metal inner liner survive in the "hot zone" of the burn tunnel and riser, and anyone who has metal working in these zones, does not have sufficient insulation value in them to obtain the extreme temperatures and complete/efficient combustion of co and creosote producing gasses, and therefore does not REALLY have a rocket, no matter how many times they call it that.
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Post by coastalrocketeer on Nov 23, 2017 15:10:36 GMT -8
The main reasons metal is shied away from, overall, for outer cladding and such is most of us don't have ready access to the fabrication tools, materials and/or excess funds to acquire them. We can much more easily obtain clay, concrete, and other masonry material for our systems and keep the energy intensive and costly "bought" materials to a minimum...
Since you have access, don't let that discourage you... Just remember... Heat must be retained in the hot zone through high temp insulation, and can be dissipated/stored/conducted away only AFTER that super high temp, high efficiency combustion is achieved, a zone inside the stove wherein metal exposed to the flame path dreary, is definitely doomed.
Ceramic fiber blanket and LD (low density board) are great high temp refractory insulation... An inch of either beating 6-10 inches of perlite-clay mix for insulative value.
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