[Stoves] Mis-information

[Ronal W. Larson]

Paul, list, and cc  (this also responding to Kirk Harris)

	 I should have added the names:  Nat Mulcahey,  Lucia, and World Stove.  Nat’s stove looks identical to a TLUD, but clearly operates with hot N2 and CO2 (no oxygen) traveling downward through the fuel bed.  Well discussed I think at the 2009 ETHOS conference and elsewhere. Nat says that it is the lack of red glowing embers near the top that shows there is downdraft.

	The low pressure at the bottom is caused by Bernoulli-Venturi principles in the stove design that Nat has patented (and talks about).   I have periodically tried to find equations to understand this effect, but never had a need to get deeply into it.  I know that Nat understands those equations perfectly (I visited Nat’s facilities in Italy, operated with and without a fan, and am sure he does NOT operate a TLUD).   Amazing to me that this effect can cause such a downdraft.  Totally non-intuitive.

	I’ll look up an exact cite, but found one video that says the experimenter (not Nat) had to increase the height location of the secondary air inlets to maximize the “vacuum” effect (lowered pressure below the fuel).  That geometry is not common in TLUDs.  It is also very different from Nat’s apparatus (which has "complicated” aluminum castings), which he “tunes” for different fuels).

	It is interesting to ponder whether Nat’s patent would cover this quite different (and simpler) geometry.  Maybe it has been done by others, but Nat can control the power level, and the simple (Facebook) tests I saw were not (but probably could).   Nat has other stove features that possibly would not have him worry about this apparently similar “)TLODD” behavior   (Although “ODD" has meaning, it probably implies a curiosity aspect that is not deserved.  I want to take that name back.)

	Why would anyone want to further explore this “downdraft” effect?  Besides Nat getting  a very clean flame, that I now presume could also be achieved with tin cans with the new secondary air hole placement,  I’m guessing that this system could be optimized to give a pre-mixed flame.   That would give shorter flames.  Possibly can have shorter stoves that can be filled closer to the top.

	Measuring the temperature below the fuel bed will tell a lot.

	Thoughts?

Ron



> On Mar 21, 2018, at 10:59 AM, Paul Anderson <psanders at ilstu.edu> wrote:
> 
> Ron and all,
> 
> I will send a full response very soon.   Believe me, the explaation does not justify a new category of micro-gasifier technology, but is only TLUD done poorly.
> 
> 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 3/21/2018 9:25 AM, Ronal W. Larson wrote:
>> Paul and ccs
>> 
>> 	I believe the downward movement description is OK.  Not a TLUD, of course, despite its looks.
>> I’m at a conference and will say more later.
>> 
>> 	I know you don’t like the term TLOD, where “O” stands for opposite.  How about TLODD (for Top Lit Opposite Down Draft) - since the issue now is “down”?
>> 
>> Ron
>> 
>> 
>>> On Mar 18, 2018, at 3:32 PM, Paul Anderson <psanders at ilstu.edu> wrote:
>>> 
>>> Stovers,
>>> 
>>> I stumbled onto this video by accident.   He is instructing (64,000 views) that the air in the fuel chamber of a woodgas stove (same drawings as for a TLUD) are moving DOWNWARD.
>>> 
>>> https://www.youtube.com/watch?v=FepZPaxgB3o
>>> 
>>> Totally bogus.
>>> 
>>> I would not even mention it to the Stoves Listserv except to express my disgust and to point how what is creeping into information flows about stoves.
>>> 
>>> Might be a nice challenge for students to try to PROVE the direction of the air flows in TLUD stoves.   Such as an increase in temperature in the bottom few cm of the fuel if the hot gases were pulled downward.    Of detecting combustible gases in the gap between the fuel cylinder and the outer cylinder.
>>> 
>>> 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
>>> 
>>> 
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