Monday, February 17, 2014

cold air falls, warm air goes sideways???

Ok, so, yeah, um... the Mark II is a completely different animal than the Mark I rocket stove from the last post.

First the physical features:

 As you can see below the Mark II is a cinder block design.

 Actually that would be an (almost) whole 8x16; a 8x8 half cinder block, and a 2x4x8 brick in the same material.
As you can see the brick constrains the size of the hole in the one side of the cinder block while the half cinder block raises the height of the other hole. And between them...
some maniac (i.e. me) has bashed half to two thirds of the divider out with a hammer and chisel.

There are also two pavers for a floor but those are optional.

Now for the theory:
same basic idea as the Mark I in that we're burning in an insulated space that will intensify the fire's heat and increase burn efficiency. But, in the Mark II instead of air coming in under the fire it is dropping in on top of it.  Er um but wait! the air is coming in on top? but it has to go out the top because heat rises... sure it does but today it's going sideways then rising. Folks like my dad and the blacksmiths he associates with up in Maine are familiar with the idea of a side draft chimney for a forge, well this is doing the same thing. Because we are constraining the space on the first (lower chamber) the expanding warm air has to go some where and it can't all go straight up, so it goes into the second (taller) chamber and can easily go up from there. This pulls more air sideways and higher than the top of the first chamber allowing cold air to fall in. cold air comes in gets heated up and evacuated at a higher temperature and pressure once again we're at a jet effect.

Here is the Mark II with it's first official burn load:

This is the same load out I gave the Mark I on it's second and third runs:

And the burn tests:

Round one: tried matches. The second and third matches burned better than any of the ones in the Mark 1, but still didn't have quite what it takes so...

once again out comes the torch...

Round two: this one catches immediately and doesn't upchuck it's paper the way the Mark I did (I went for a 'non windy' day but a gust or two did show up.

As you can see (or not see) the Mark II doesn't put out a lot of smoke (that is what we call a good thing) and put out even less as it got going. And as for the warm air/fire...
Yes friends it does go sideways then turn the corner!!!

Now for the after effects:
It burned it's load pretty fast (definitely less than 10 minutes I'm guessing less than five but I wasn't doing a time test this time. And it burned pretty efficiently (again not being uber sciency, this time)

you can see the ash/residue in both chambers (nothing has been removed or added but I did stir it around) and that there wasn't much carbon on the side either... you can see some bits in the burn chamber are still glowing red.

Successful test!

Now we will start testing larger wood, other fuels and (oh yeah!!!) what can I actually DO with this thing. Hoping at minimum to have a shop warmer and water/soup in a cup heater and would really love it if I could get some metal melting or steel banging temps out of it (note DO NOT prepare food/drinks with the same cinder block that you melt or otherwise heat metal with!)

After the tests we made a run to 'the cowboy store' to pick up a couple things and get Lisa away from her computer, and I found a new starting option:
These things are a sort of combo match and kindling that is supposed to burn for seven minutes. If they work that's another problem solved (Now why wouldn't Lisa let me get the Magnesium fire starter...)

Yes I really am going to weigh in on the stamping thing (maybe next week), recipes will creep in  (now if I can keep from titling that one "sour DOH!"), and we get plastered (sorry party people it's not what you think).

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