An experiment with bricks, mud, water and fire. Lots of fire.

By adding a separate combustion chamber between the firebox and the chimney, one can allegedly persuade more hydrocarbons to break up their relationships, thus releasing more energy.  Let's see...

Back in the day, they used to make those upright, cylindrical feed silos out of twin-core ceramic blocks. I've put one in the middle of some bricks where it will serve as the combustion chamber.

Notice in the foreground the lightly-curved section of brick?  These regular bricks are also from a silo but this one was mostly a hole in the ground with an eight-foot wall of brick surrounding it to keep the kids and cows from falling into the hole.  As for the structure in the background, that's the exhaust hole.  It's on the south side, which will become important later.

The first test burn was pretty discouraging. I decided to add a second silo block to double the combustion chamber size.  Then I started to collect materials for the build.

That's the mortar mine. I got several loads of last year's old, ground hay from Mitch so a little of that is being used as rebar.  Ideally one would use a clay soil but this dirt pile was conveniently located right next to the lab.

As it's actual mud, mixed with cat feces, broken glass, rocks and bits of wire I was curious as to when I'd first be bleeding into the bricks. So far, no major cuts (knock on blocks).  A side-effect from mud work is that the camera stays well away from the action.

Fire enters the combustion chamber from the bottom, rises up and spills into a larger bell-shaped area with a single exhaust port at the bottom. A crucial component is the lid of the combustion chamber.  I used an automobile wheel.  Bricks and rocks keep the mud from falling thru the various holes in the wheel's structure.

Looking south into the combustion chamber where the fire sits. The prevailing wind is from the south.  I'm trying to get a fire started on this, the north side with a breeze blowing into the exhaust, through the innards and into my face. 

So the chimney arrives.  It's kind of stuck onto the backside in a casual, carefree fashion, making the earlier construction seem over-engineered by comparison.  While holding the plastic tube from blowing over in the wind, I first learned to take a too-wet handful of mud and just fling it into place; a time-honored technique that I'm starting to enjoy.  The smoke test shows minor flaws in the construction.

Time passes.

Having failed to get a good burn on the first, second, third, etc. attempts, I return after lunch to spend at least an hour fussing around with the air/fuel mixture, digging out the burn area tunnel and just generally getting all smoked up.

Then one time I looked up to see steam coming out the chimney, so I went and got the camera.

I could hold my hand over the exhaust.  It was warm, maybe 150F or so but not painful.  The desired exhaust from one of these contraptions is supposed to be warm air and water.  All the other stuff is supposed to be completely disassembled in the combustion chamber.

Looking up the burn tunnel.  At this moment the exhaust is pretty much all steam.  You can see a wee bit o'smoke playing around the entrance.
This first sketch of a rocket stove/mass heater is marginally successful.  It only started "rocketing" a couple of times and only a few seconds each time.   Perhaps there is a slight error in calculation or construction.
By using mud and bricks it will be quite easy to dis-assemble and study the innards.  Just add water to re-assemble.


Update

On Saturday there were two adjustments made prior to lighting the second fire. The car wheel was inverted to create a larger dome over the combustion chamber and the vertical firebox/fuel delivery chute was re-installed.

Taken at the same time as the previous photo, these images show no smoke, no steam, just hot air (but not extremely hot) exiting.

Time to quit; other chores need attention.  The concrete block fuel chute is now cracked. Rolling it away reveals a seriously clogged up fire tunnel.  The top of the dome was still warm to the touch several hours later.