Wood stove for cooking and hot water

[motas]

Browsing the internet I came across the rocket wood stove and got me thinking about its application for camping. For those not familiar there is a close to vertical tube that feeds small pieces of wood into a horizontal combustion chamber which then hits a 90 degree bend and a vertical insulated chimney. The turbulance of this bend draws in extra air and the insulated chimney causes very high heat. theres specific requirements but basically its a really efficient hot fire.
I have seen people mount conventional stoves in a camper and wondered if this could be more suitable. So wood could be fed into an external tube which if long enough would provide many hours of heat. a cooking surface could be installed above the chimney and pipe wrapped around the chimney to heat water. The design I have in mind there would be no openings to inside the camper so there should be no worried of fumes or smoke.
The main concerns I have is how light this could be made. How quickly it would get to a useful cooking temperature. How compact it could get while still being useful. And if it is possible to insulate it well enough to not have safety concerns.
I will post up a basic sketch when I have time.
Thanks.

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[RememberTheFallen]

I really like the rocket stove designs. They are very efficient as they get hot on very little wood. Even though they burn fairly clean (they are pretty much smokeless after start up) I would still worry about CO inside an inclosed shelter. Weight would be another concern. The ones I have seen use permiculite (sp?) to go around the vertical tube. Although not super heavy it is by no means a lightweight product.

I have been looking for a good candidate for the main body of the stove. I have seen everything from a gallon paint can to a 55 gallon drum used. I think one pop corn can size or 13 gallon size would be a pretty good compromise.

I think it could be done if make sure everything seals well and you keep a CO monitor close by.

I would like to see your plans.

 

[motas]

The design I have in mind has no openings in the camper at all. Weight is a major concern. I have seen ash be used as insulation. It is not flammable, cheap, easy to get and light. Not sure how effective it is though. I was thinking stainless steel or something similar to build the whole thing out of to keep weight down. I might try it out on the cheap and heavy with old drums I have plenty to choose from and see if I can get it compact enough to be feasible.

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[motas]

Terribly crude sketch between lectures but its the basic idea. Greens are the confines of the camper. So there would be a tube running from an external wall to the fire which acts as a fuel slide. Basically I can just collect a whole bunch of small pieces and throw them down and it self feeds. Longer the tube the longer it will burn for. This then meets the combustion chamber which burns side ways. Not sure on the exact science but basically when the heat hits the 90 degree bend it creates turbulence which creates a good draft drawing more air into the fire. The insulation around this area keeps it extremely hot which burns the chemicals in smoke as well. This then hits the cooking surface which should even in a compact system get quite hot. Then the smoke fills the outer chamber which id imagine would be more suitable temperature to heat water safely and then goes up and out the chimney on the roof.
Also to light it id have a removable hatch on the outside. And blue is insulation so the only hot part would be a cooking surface on top. I am not interested in heating the camper so would possibly make an insulated cover for that part as well.

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[Doc2012]

I think your logic for the "self feeding" aspect is a safety hazard.

You start shoving sticks down that tube, what's to stop it from the flames from coming back up? As you know, wood burns quicker on the outside, so it would leave the solid center sitting in the pipe.

As far as stainless, I wouldn't use that. It's not very light.

I would go with aluminum. It's light weight, and doesn't stay hot for very long, but would transfer the heat fairly well.

To heat the water, I would wrap some copper tube around the exhaust shaft, and have a basin sitting either above, so it's gravity fed, or below, using a pump. Run the tube out and put a faucet on it.

I think the ash would be a good idea for the insulation. Just double up the tube on the exhaust port.

Actually, I would do that on both ports.

Use a 3" tube for the "feeder" and the exhaust, and say a 4.5-5" for the outside. Then pack your ash in between, and you should be good to go.


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[motas]

A cap over the wood feed stops any air flow going up through there smothering any fire. Good point on the aluminium it does conduct heat much better than steel and wont corrode. Also this would be used with small wood not logs so it would feed properly. Would the water heating be a safety hazard? I figure if it is a small essentially open system it will push water out before holding enough pressure to be dangerous. I only want to run it to a faucet and a shower through a pump. Total tubing would only be a few metres. Still not sure whether it would be compact enough to fit while big enough to be useful but a steel version made of scrap could be a cheap test. At this point its just a concept though. Cheers.

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[Doc2012]

I don't see why the water would be a safety hazard, especially if it's an open system.

For "safety's sake", put a pressure relief valve in there somewhere, just as a bypass incase it does get too hot.

The problem I see happening, is the fact that the water might be too hot to even use. Especially if the fire reaches it's optimal temperature. But, again, that's something you'll have to fool around with.

As I suggested before, take some copper tubing, say 1" ID, and wrap it around the inside of the exhaust tube.

The issue then would be getting the insulation down there, ensuring it's COMPLETELY filling the space between the inner and outer tubes. Of course, you can get creative and fill it, but that's your issue. Lol.

The other thing I see an issue with is the coals. There needs to be a way to stop them from burning. Weather it's pouring some water down the intake tube, or some sand or something. There's got to be a way to stop them from burning.

I'm really interested in these "rocket stoves" now. Lol. I'm trying to design a camper off an M116A2 trailer, and I think I might try to incorporate one in there some how. Maybe not, but if I have he space, I'm seriously considering it.


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[motas]

I think the best way to stop it burning would just be to cover the intake and possibly the chimney. It might keep smouldering for a little while but would go out soon enough. Otherwise water and a drain plug would do the trick. I think temperature would best be controlled by a mixer. Maybe a two water pumps one hot and one cold and just vary the speed of each. But I could work out through trial and error how far along the system to put it so it would be useable. I dont think the ash would be too hard to fill just might take some time shaking it around.

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[hennhauss]

Check out the Kelly kettle or the Ghillie Kettle. They are a consumer version of what you are describing.


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