I've been very impressed by the work Peter and others have done to improve the RMH. My first thoughts are to build a RMH based heavily on Peter's design using firebrick and other standard materials where ever possible, and making the non-standard parts.
The tripwire is the first thing that comes to mind. As I see it, I have a couple of choices; casting it, or cutting one from a fire brick.
First. My gut tells me that the lip on the riser side should be squared off (have a minimal radius) for it to work best. Is this right?
I would like to get several years use from the stove, if possible. Any thoughts as to the long term durability of these two materials? I have very little knowledge of either. Will one hold up better to erosion by the gas flow, and the occasional bump from wood while being loaded.
What about cracking? Should any inside corners be made with a smooth radius to minimize crack propagation?
Is the insulating firebrick o.k?
Hopefully the castable material will hold up, as I'm beginning to think it might be easier to make the exact size and shape I want from it.
My gut tells me that the lip on the riser side should be squared off (have a minimal radius) for it to work best. Is this right?
No it isn't. This will work just because the trip wire ridge end abruptly. There's an exact location, about 2 or 3 inches behind the p-channel proved to be the best distance. You have to implement the p-channel as well, without it, the effect isn't as pronounced.
Any thoughts as to the long term durability of these two materials? I have very little knowledge of either. Will one hold up better to erosion by the gas flow, and the occasional bump from wood while being loaded.
When cast very precise and with the right material, this will stand for years on end. But it's difficult, better use a grinder to cut it out of a fire brick when you don't have experience of castable refractories.
What about cracking? Should any inside corners be made with a smooth radius to minimize crack propagation?
Cracks are not the problem, usually. When you decide to use castables, it's nicer to round or chamfer the corners. Not the one leading from the tunnel ceiling to the riser, by the way. The lower corner where the tunnel floor meet the riser could be rounded in such a way that the csa of the system is maintained. By doing this, the ash wouldn't build up as easily.
Many years ago I did some work developing pieces to be used for holding resistive-electrical elements in electric furnaces. We mostly formed them from loose ceramic fibers, but did some work with castables. As i recall we bagged the mold and applied a small vacuum while it was being shaked. This resulted precise dimensions, and no voids. We Xrayed them to be sure.
Hmm this could be interesting! And if it doesn't work out, I can always cut up some bricks. Pete
I have some thoughts on a "tripwire" setup that is fairly simple to create for a brick burn chamber.
Here is the premise
The cutting pattern. The bend must be 36 degrees towards the feed tube or P-channel. An acorn nut placed between the next row of bricks will assist the vortex creation. 1/4" (6mm) black steel should be heavy enough as there is not much heat in the area.
This one has a maximum width of 3" (76mm) reduced to 1.5" (38mm). If you wanted to add these throughout the burn chamber they could be made much smaller. Not the radius of the acorn nut (half circle above) rendered drawings
The bend must be 36 degrees towards the feed tube or P-channel. An acorn nut placed between the next row of bricks will assist the vortex creation. 1/4" (6mm) black steel should be heavy enough as there is not much heat in the area.
Errmmm... In which direction is the plate sloping down? The ridge is at right angles to the stream, that isn't the most effective position. The 1/4" steel will burn away in no time, in that particular area there's an awfully hot environment, among others caused by the trip wire itself. The brick wires made by Donkey and others are very effective, pointing the right direction, are positioned at an angle to the stream and it will hold for years. Why make another, more complicated and vulnerable variant?
Last Edit: Aug 2, 2014 8:05:00 GMT -8 by peterberg
The bend must be 36 degrees towards the feed tube or P-channel. An acorn nut placed between the next row of bricks will assist the vortex creation. 1/4" (6mm) black steel should be heavy enough as there is not much heat in the area.
Errmmm... In which direction is the plate sloping down? The ridge is at right angles to the stream, that isn't the most effective position. The 1/4" steel will burn away in no time, in that particular area there's an awfully hot environment, among others caused by the trip wire itself. The brick wires made by Donkey and others are very effective, pointing the right direction, are positioned at an angle to the stream and it will hold for years. Why make another, more complicated and vulnerable variant?
Top view. P-Channel air feed would be on left side
The plate slopes down and faces the direction of the incoming air (right angles) from the P-Channel, possibly between the first brick and second brick. Common metals would be steel but to go with a much better metal for the job I would choose either tungsten or titanium.
Cost and availability is a factor for home built units and the incoming cooler air from the P-Channel should help to prevent the steel from burning away. Also filleted leading edges would help. If using tungsten or titanium you could use a piece as thin as a putty knife blade.
Here is another design based on a round burn chamber and could be inserted on either end, or both, and possibly even in a round P-Channel. This idea comes from the science behind how forest fire tornadoes occur.
Below is an insert concept based on the Viktor Schauberger vortex. Fillets and angles not shown but again are 36 degrees for angles. I have not wind tunnel tested either of these designs but they are already proven. I think they could be cut from some heavy guage sheet metal for a more practical test.
A friend and I do creation and design development work in green energy areas: Solar Furnaces (patented and commercially available), Savonious S Rotors, Buoyancy Gravity Air Transfer Engines and in Solar Nuclear Thermal Reactors (3000-5000C+ temperatures).
Maybe it will work, maybe not. I've tried several trip wire setups, the one with the best results was facing down the other way. But please, build it, test it, and show your results. I like good ideas, especially when tested thoroughly.
Maybe it will work, maybe not. I've tried several trip wire setups, the one with the best results was facing down the other way. But please, build it, test it, and show your results. I like good ideas, especially when tested thoroughly.
Most of this has been tested in other applications, just not in a RMH.
I will be using Flow Design to tunnel "test" the designs and only to happy to provide you with the videos. Currently I have been having some issues with the software. Once those are solved by AutoDesk, rapid design and testing will be straight forward.
I am also working on a design for a longer P-Channel shaped like a "U" on its side. Air enters from the top takes a turn then down the "U" shape 8" X 1.2" box tube, around the bend returning on the next level (lower) which is near the top of the burn chamber. then back to the side of the feed tube flush with the feed tube and down to the burn chamber as in a normal P-Channel. One, it will heat the incoming air. Two, hopefully, will create quite a stack effect from the additional 29+ inch length in a 12 inch feed tube. Shauberger vortex generators could be welded inside a fabricated tube (welded) for more air turbulence.
The extended P-Channel based on a 12 inch feed tube and is 7" down, 1 inch radius, 11 long run then 2 inch return radius, 11 return and another 1 inch radius and an 8X 1/2 inch run towards the burn chamber and the air outlet.
You mentioned that having the P-Channel feed heated air to the burn chamber was an advantage. My concern is how close to place the "U shaped" boxed P-Channel feed to the burn chamber. If in direct contact I am worried about the P-Channel system getting very hot and possibly reversing itself and taking air and unburned gasses from the burn chamber. The stack effect of the RMH's exhaust system makes me also think that my first concern won't happen.
Additionally anything I post here is public domain.
One advantage with the forward facing metal bracket is it is easy to make and just stick into the air flow.
i notice that the drawing from the patent is for a water based system. not sure of the density of the air in the burn tunnel of a RMH but it certainly isn't the same as water.what works fine in water will not work the same in air. don't let that stop you experimenting though and please post your results here.
i notice that the drawing from the patent is for a water based system. not sure of the density of the air in the burn tunnel of a RMH but it certainly isn't the same as water.what works fine in water will not work the same in air. don't let that stop you experimenting though and please post your results here.
The densities are different and air at various temperatures has different densities but they are both fluids and behave as such.
Have a look at this Fluid Dynamics Simulation. You can use different barrier shapes, wedges, diagonals, circles, etc as well as change viscosity. The dynamic viscosity of air at at 1326C is 5.63 and a bit beyond the range of this simple simulator but the simulator will give you some visuals on the various barrier shapes and what is going on.
An aside: If you want to build a RMH beast you could add water via a small Brumisation nozzle at the end of the P-Chanel as water turns to HH + O at 1,350º C. It would be equivalent to turning on the F-18's after burner in your home. While the water would have a slight cooling effect the additional hydrogen and oxygen molecules would supercharge the burn. It would probably sound like Peter's pulse jet video X10.
An aside: If you want to build a RMH beast you could add water via a small Brumisation nozzle at the end of the P-Chanel as water turns to HH + O at 1,350º C. It would be equivalent to turning on the F-18's after burner in your home. While the water would have a slight cooling effect the additional hydrogen and oxygen molecules would supercharge the burn. It would probably sound like Peter's pulse jet video X10.
Even if it where possible to reach 1,350º C: Perpetuum mobiles are impossible. It needs more energy to break the bonds than can be regained.
An aside: If you want to build a RMH beast you could add water via a small Brumisation nozzle at the end of the P-Chanel as water turns to HH + O at 1,350º C. It would be equivalent to turning on the F-18's after burner in your home. While the water would have a slight cooling effect the additional hydrogen and oxygen molecules would supercharge the burn. It would probably sound like Peter's pulse jet video X10.
Even if it where possible to reach 1,350º C: Perpetuum mobiles are impossible. It needs more energy to break the bonds than can be regained.
I should have said "Theoretical Aside" or possibly not said it at all as it is off topic for this thread. My apologies for that. :-)
I was not referring to or even thinking of a perpetual system, just getting more heat from common materials. A Brumisation nozzle + the mini pump to power it is far too high tech for a home built RMH. HHO systems for cars are in use as are hydrogen oxygen fuel cells and are quite efficient. The 20 AMPS from the car battery is enough energy to break the bonds and power the car which generates the 20 AMPS to break the bonds.
Maybe it will work, maybe not. I've tried several trip wire setups, the one with the best results was facing down the other way. But please, build it, test it, and show your results. I like good ideas, especially when tested thoroughly.
Peter,
The long tube P-Channel idea
While it would have an esthetic look beside an 8 inch X 8 inch feed tube, the extended P-Channel as an 8 inch X 1/2 inch would be somewhat difficult to build. The 4 square inches (8X.5=4) of intake area would be better, I think, as a round P-Channel tube.
4 square inches is the opening area of a 2.25 inch diameter pipe (5.7 cm). The iron pipe and fittings are easy to obtain. Black iron pipe nipples and 4 - 90 degree elbows would be all that is needed and not too costly.
The end entering the burn chamber could/should be dipped in a ceramic slurry (refractory grade) or possibly a high temp ceramic clay to prevent the pipe from being "eaten".
Maybe it will work, maybe not. I've tried several trip wire setups, the one with the best results was facing down the other way. But please, build it, test it, and show your results. I like good ideas, especially when tested thoroughly.
fierolepou: Hi everybody! Starting a project from scratch, this is a goldmine!
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Solomon: Best way to not die in a house fire is to build a stove where the really hot stuff isn't near the flammable stuff.
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beppe: Hi to everybpdy. I'm new about the rocket stoves and this forum
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beppe: I have a living room+ kitchen of 75 square meters that was heated by an ordinary pellet stove with a power of 8KW.
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sksshel: Yes, very happy with my DSR2. I had not heard about the DSR3. I probably won't be using it but I will look into it.
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rockinon: I have some questions about a Rocket Mass Heater, as I am in progress of getting a place built in Arkansas in the mountains of NW Arkansas and it will be very helpful. How can I add pictures to illustrate what I am requesting
Jan 23, 2024 11:01:07 GMT -8
dd24: Bonjour, Quelqu'un expérimente t-il sur les poêles "bubafonya" ou "stopuva"? merci pour votre réponse!
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marcios: Hi Trev, What dimensions did you keep for the top chamber?
May 9, 2024 13:41:47 GMT -8
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Donkey: rockinon, place them on some other web hosting service and link them here.
Jun 27, 2024 16:25:24 GMT -8
atrii: How can I see these photos Donkey?
Jul 16, 2024 16:17:59 GMT -8
Donkey: atrii When the images are properly linked, they will be visible.
Jul 21, 2024 19:02:47 GMT -8
dvawolk: For images i use "Greenshot" app - i can print screen part or whole of my screen and upload them directly to imgur throught the context menu. Works very well and fast for me...
Aug 21, 2024 2:21:17 GMT -8
martinm: Hi there , looking for info on hot water heat exchanger for integrating in the bell of masonry rocket stove.
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lightworker: Hi beppe:
Oct 19, 2024 16:45:02 GMT -8
