Use larger feed chamber (for logs), but small riser?

[joseph]

Nov 11, 2013 21:16:35 GMT -8 Donkey said:

Bigger feeds with J-tube rocket stoves haven't been found (as of yet) to do well, batch-box heaters overcome this short-coming.. BOTH need to burn hot and fast for clean combustion.. In fact, rocket stove design ITSELF is about hot, fast fires for clean combustion.
The solution to the "too much heat too fast" problem (so far) has been MASS.

For some reason, you don't want the mass... So, maybe a smaller stove with a continuous feed, like the rocket pellet stove on this thread.
But you want to feed it large cord-wood...

Tall order, each stove you might choose has it's own parameters for proper use. The way I see it, you now have a choice:
(1 live within the KNOWN parameters of (one of) each of these designs
(2 Choose a different kind of stove (not a rocket) and live within it's parameters
(3 Build something entirely new, perhaps based on rocket stove design and set NEW parameters (that will then have to be lived with)

I am familiar with the Riley stove, and also the Clarry, mentioned on that thread you gave. They do what I want, except they use pellets, which must be purchased. I would like to do that with tree wood.

In the Clarry, a 40 pound bag of pellet wood burns for 8 hours. I would like 40 pounds of dry tree wood to burn 8 hours. I know it's not quite the same thing, but it should be possible, with the proper draft, and proper engineering.

I choose #3.

[Rinchen]

Updraft in my opinion would be the best way to go, with the wood tightly packed together and a strong draft.
It is likely though that you will draw in a lot of excess air in order to keep the wood cool enough.

[joseph]

Nov 11, 2013 23:30:35 GMT -8 satamax said:

.... Have you built yourself any complete rocket? Insulated it properly?

I only built the feed chamber to the riser. I did not think that a properly sized barrel affected combustion; does it?

The riser is very much insulated. I am using 1.25 inch thick firebrick for the burn chamber, and it has some insulation on the outside.

But I will have to make it bigger to do the test with bigger wood.

[Deleted]

To be able to burn very very wet wood in a cooking stove
I have combined a 3" feed and a 3" raiser with a 4" burn chamber.
Works like a charm.
Once it got hot it can burn the thickest sticks one can place into a 3" feed.
Combining 5" feed and raiser with an 8" burn chamber should be possible,
although I do not think that a 4.5" piece in the 5" feed would burn for eight hours.

[joseph]

Karl:

Thanks for the info. I think that in my testing, I introduced the large wood too early, without letting the firebrick in the chamber get fully heated. So I will try again. I will also try a larger chamber.

I am not expecting one log to last for 8 hours; I was going to feed from a magazine (yet to be constructed). I just want a slow, steady fire, like the Clarry stove, but without pellets.

[satamax]

Joseph, so, now you're letting the sail go.

One untested solution, this is theory.

Logs branches etc, can be turned to mulch with a wood shredder. I think this could be an easy solution to replace pellets.

Your magazine idea, i think is bound to bind. Well may be not. But that what they usualy do

[woodrascal]

May be a batch with the logs falling down like a gun magazine could do something good.



I've got a weird hybrid rocket/cast iron woodstove in my workshop with a fairly tall (in relation to the heat riser) and wider feed box. Once the rocket is up to temperature I fuel it with short 130mm ish lengths of oak and ash branches stacked HORIZONTALLY that then autofeed into the fire. To prevent blow back I have a cast iron lid that I slide over the feed tube opening that also helps to regulate the draft. Have I made a mini 'batch box'?

[satamax]

Nov 12, 2013 14:02:47 GMT -8 woodrascal said:

May be a batch with the logs falling down like a gun magazine could do something good.



I've got a weird hybrid rocket/cast iron woodstove in my workshop with a fairly tall (in relation to the heat riser) and wider feed box. Once the rocket is up to temperature I fuel it with short 130mm ish lengths of oak and ash branches stacked HORIZONTALLY that then autofeed into the fire. To prevent blow back I have a cast iron lid that I slide over the feed tube opening that also helps to regulate the draft. Have I made a mini 'batch box'?

Duh, 23h22 here, and it's hard to picture. Any pic?

[joseph]

Nov 12, 2013 14:02:47 GMT -8 woodrascal said:

...Have I made a mini 'batch box'?

No, you have a J-rocket with an automatic feed. (as far as I understand)

The 'batch box' would burn all the wood at once.

[satamax]

Not at once, but in 20 minutes or thereabouts With big pieces, i can manage to have relightable embers after two hours in the green machine.

[joseph]

Nov 12, 2013 13:05:24 GMT -8 satamax said:

... Your magazine idea, i think is bound to bind. Well may be not. But that what they usualy do

If it binds and the fire stops, that's a nuiscance.  If it binds, and sets fire to the rest of the logs in the magazine, that's a problem.

I intend to not let the second thing happen by not allowing the magazine to get a draft.