[Stoves] Down with Fantasy-draft stoves

[alex english]

Hi Stovies,

This relates to Paul's doubts that all the air can come in the top of a TLUD
.

I took two off the shelf items and with no alterations and made a
serviceable stove for wood pellet fuel . I placed a stainless holey cutlery
strainer on a shim in the bottom of a small stainless milk pail. The
strainer is 4 5/8 inches in diameter and 5 inches tall. The top was about
3/4 of an inch below the top of the pail. Half filled with pellets, which
leaves the pellets 3.5 inches the below the pot.  Top lit, it burned for
about 45 minutes with all the air coming in from the top. The migrating
front headed 'south' predictably. A little ash formed around the edges.
Good flame stability.

It is basically a one speed device unless you manipulate the fuel profile.
The pot position, size and shape is a factor as the exhaust and air pass by
each other in close proximity going in opposite directions.

A pretty simple stove.

Alex


On Thu, Mar 29, 2018 at 8:39 AM, Paul Anderson <psanders at ilstu.edu> wrote:

> Alex (and others)
>
> You wrote:
>
>> That primary air  can be introduced above the fuel with the secondary air
>> and drop down and spread out below the
>> pyrolysis front.
>>
>   I would certainly like to see this demonstrated (visible) or supported
> by scientific measurements.  Frankly, I have my doubts, especially if it is
> less than 20 cm (8 inches) in diameter..
>
> Paul
>
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype:   paultlud    Phone: +1-309-452-7072
> Website:  www.drtlud.com
>
> On 3/29/2018 5:40 AM, Andrew Heggie wrote:
>
>> 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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