[Stoves] Cuber and size of densifying machines. (no longer Re: The wood and char and fuel "debate" )

[Dean Still]

Hi Paul,

I think that the denser pellets might not maintain the flame as easily as
the .56g small pellets described by Tom. I wonder if for clean emissions
the TLUD has to be tuned to burn the fuel even if the tuning is easily
accomplished by adjusting primary and secondary air.

Best,

Dean


On Thu, Mar 6, 2014 at 11:35 AM, Paul Anderson <psanders at ilstu.edu> wrote:

>  Stovers,
>
> Crispin wrote, in agreement with Dean, and I have added the emphasis on
> Crispin's words:
>
> The air flow through the pellets strongly affects the way they burn* if
> the device is constructed such that the fuel contributes a significant
> element of air control.*
>
> Simply, stove devices should NOT be constructed for a specific fuel UNLESS
> that fuel is specified and can be supplied.   The issue is just like using
> an incorrect grade of gasoline in your automobile.   LEADED gas will not
> burn like unleaded.   Super premium is different from regular.    And
> pellet sizes are different from each other (assuming that the pellet
> materials were also the same, which might or might not have been the case
> in what Dean has mentioned.)
>
> Most of the TLUD stoves that have been tested have not been the ones with
> serious control of the primary air supply.   Hence the problem that Dean
> mentions.
>
> I do not know of any tests of emissions from different pellet sizes that
> have been conducted in TLUD stoves that have serious control of primary
> air.   One more research topic to add to the list of things to do.
>
> Personal comment:   I have had my hand involved with the development of
> the "Champion Family" of TLUD stoves:
> 1.  Champion TLUD that won the first Cat Pee Award at Aprovecho Stove Camp
> 2005.   We just had a blocker on the primary air inlet.
>
> 2.  Champion by Servals (India):   Still with a rather rudimentary control
> of primary air (a disk into a cone).
>
> 3.  Mwoto (for BEIA project by CREEC in Uganda):    It has a slider
> control of primary air directly on the fuel cylinder, but we had not
> perfected it then and did not make much of an issue about closing off the
> primary air through tiny gaps such as at the ends the strips that hold the
> slider in place..
>
> 4.  Quad (by Awamu in Uganda):  We made a better slider door and placed it
> onto  a "snout" for primary air.   But we did not seal with great care.
> Also, the tab-and-slot construction left tiny  air leaks that proved to be
> too much uncontrolled air.   This was discovered at the July 2013 Stove
> Camp at Aprovecho where we progressively sealed better and better the
> stoves being tested.   The best sealed stove won one of the Cat Pee
> Awards.   That was seven months ago, and we have stopped production of the
> Quad stove with tab-and-slot construction (and have sealed better the
> existing units.)
>
> 5.  Troika Bingwa (by Awamu in Uganda):   This stove is just getting out
> to the users.   It has a tightly sealed fuel chamber with a slider over the
> primary air entry.
>
> Note:   Do not underestimate the impact of even a very very very small
> leak of primary air if you expect to have turn-down of a TLUD stove.
>
> Of all the other TLUD stoves, most have no attempt to control the primary
> air.   The unit by Prof. Nurhuda does seem to have excellent primary air
> control (but I do not have one of those stoves, and there are additional
> issues to be considered.)
>
> I hope that these comments are useful for everyone dealing with natural
> draft TLUD stoves.   Comments pro or con are most welcome.
>
> 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 3/6/2014 11:38 AM, Crispin Pembert-Pigott wrote:
>
>  Dear Friends
>
>
>
> I agree with Dean on this score. The air flow through the pellets strongly
> affects the way they burn if the device is constructed such that the fuel
> contributes a significant element of air control.
>
>
>
> These devices
>
>
>
>
> Are 'cubers' in that they are producing densified lumps that can be put
> into a stove. But they will work best in a large stove such as is used in
> China for space heating and cooking.  The input material is straw and other
> stover.
>
>
>
> The mechanism is an eccentric roller running inside a perforated cage at
> maybe 60-100 RPM. As Tom notes, power consumption is about 110 kW.
>
>
>
> So far I don't think the product is economically viable as there is a
> subsidy involved. What we need is a breakthrough technology that will make
> densified fuel without the need for heat.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
>
>
> Hi Paul,
>
>
>
> I have seen the very small pellets sold for heating stoves in the US burn
> very cleanly. Larger sized pellets did not burn as cleanly.
>
>
>
> Best,
>
>
>
> Dean
>
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