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

[Paul Anderson]

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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