[Stoves] Down with Fantasy-draft stoves

Andrew Heggie aj.heggie at gmail.com
Thu Mar 29 05:40:33 CDT 2018


On 29 March 2018 at 01:32, alex english <aenglish444 at gmail.com> wrote:
> Andrew,
> If you are curious you can 'freeze' theTLUD process at any point by setting
> the a TLUD in a pan of water that shuts off the air and wicks water into the
> raw pellets in the bottom of the fuel chamber. They will swell and wick all
> the way up to the Migrating Pyrolysis Front . The Torrefied layer and the
> char above will not swell. A careful excavation of the fuel will reveal all.
> When I did  this with the 18 inch diameter chamber I found a horizontal
> layer of an inch, or a bit  less, of pellets in transition from raw pellet
> to torrified pellet to charred pellet.

Thanks again Alex it's an interesting experiment but I'm quite happy
to take your word for the horizontal MPF.



  Misting the outside of the stove
> will can also give clear impression of a planar descent of the  MPF.

I never did much with pellets as I felt they were not a likely fuel
compared with stickwood and so not representative of most users  In UK
I find them too expensive compared with other fuels.
>
> With very dry fuel like wood  pellet very little primary air is required.
> That primary air  can be introduced above the fuel with the secondary air
> and drop down and spread out below the
> pyrolysis front.  If introduced tangentially the cooler fresh air
> centrifuges to the outside edge of a round chamber and the flame tornados up
> the middle. A layer of fresh air one millimeter thick descending around the
> edge of a fuel chamber would be enough. Not a lot of control but this
> resembles what many people have used this sort in other contexts. With
> fussy fuel quality and placement it behaves in the steady top down way that
> a TLUD does with a little extra char burning.

Yes I made many such vortex burners in my experiments, the largest
being 4foot diameter but I supplied all the air from above and
inevitably to excess.


Andrew




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