[Stoves] (no subject) (K McLean)

K McLean info at sun24.solar
Wed Oct 30 17:35:55 CDT 2019 

Ron, thanks for your comments.  I think you may want to give more weight to
Christa's comments on charcoal displacement.  I don't doubt that
displacement contributes to the improved efficiency.  The mbaula in the
Zambia testing was clearly overloaded.  Look at this photo from the report:

I think there are other factors in play, as well. What I like is a robust
discussion. I hope the discussion leads to more testing. Not just testing
by me, I am the least equipped to test. But testing by others with more
experience and good equipment. The results of my amateur testing are
significant and consistent and should encourage better testing. If we
understand the mechanisms involved, we can adjust to reach greater
efficiencies.

Let me give a quick preview of upcoming testing and testing results. SNV
has completed a second KPT on rock beds in open-fire cookstoves. They
confirmed a WBT and a previous KPT demonstrating that rock beds improve
efficiency by about a third. The KPT also found that a clay grate showed
fuel saving of 48%, confirming an earlier WBT. The report should be
finalized this week. Since they had problems with the clay grates breaking,
they will be testing a metal grate over a rock bed soon. Our hope is a
metal grate over rock bed will improve cookstoves similar to clay grates.

I have asked a couple of my amateur testers to do new tests, including
placing three rocks on top of the pile to charcoal to elevate the pot above
the charcoal. This is in response to Crispin's observation that efficiency
is lost by placing pots directly on the charcoal. The rocks may deflect too
much heat, but it is easy to test.

I'll be at the CCA Forum in Nairobi next week. I'll be there a couple days
before and after. I hope to meet some of you there. I am renting the Nyati
Meeting Room at Radisson on the 7th to exhibit (with SNV) rock beds in wood
cookstoves. I'll announce this in a separate post so it doesn't get lost in
this discussion.

On Wed, Oct 30, 2019 at 5:46 PM Ronal Larson <rongretlarson at comcast.net>
wrote:

> Christa, Kevin, list,  cc Bernhard
>
> See two sets of inserts below
>
>
>
> On Oct 30, 2019, at 2:12 PM, K McLean <info at sun24.solar> wrote:
>
> Christa, you and Crispin both suggested charcoal displacement as the
> reason for the efficiency improvement.  This is a simple explanation that
> justifies the use of rocks and a second grate in the mbaula.
>
>
> *[RWL1:   See more below on this explanation.  I haven’t yet bought
> overloading as being related to the success of either rocks or extra
> grates.   Much less the only explanation.   My reason for coming back on
> this is that stones and extra grates are a new phenomenon - that requires
> explanation in order to optimize the phenomena.  I’m pretty sure that users
> of charcoal stoves every day are apt tp know pretty well the optimum amount
> of charcoal to insert for a specific task. (And I can’t claim that
> expertise).  See more on this below.*
>
>
> * If charcoal displacement was the answer, the increased height of the
> fuel load should have deceased, not increased efficiency.*
>
>
> Do you think there may be other factors involved, too?  In the Zambian
> mbaula testing, efficiency was improved 41%.  The charcoal displacement was
> not close to 41%.  I'll try to think of other tests that allow for charcoal
> displacement.
>
>
> *[RWL2:  “other tests" was the point of my response to Bernhard;  we need
> more testing.*
>
>
> *More below.*
>
>
>
>
> On Wed, Oct 30, 2019 at 3:18 PM Christa Roth (bioenergylist) <
> stoves at foodandfuel.info> wrote:
>
>> Ron,  you keep repeating: *We have no idea yet on why simple rocks and
>> extra grates are doing so much.   (Anyone have an idea why?  My next
>> message more on that)*
>> And I have provided an answer to that numerous time and sent the link to
>> the AProvcho article on the importance of the initial load:
>>
> *[RWL3:  I have now read that paper.  There was no stove tested there than
> looks at all like the Mbaula (with no ceramics and its plentiful holes near
> the top).   I am sure that one can get bad efficiencies when you overload
> any stove.   But that does not seem to be what is happening here.  Making a
> stove look overloaded is improving efficiencies - no0t decreasing them.*
>
> You can save an enormous amount of charcoal if you limit the amount that
>> people load into a stove. The Zambian brazier is completely overpowered as
>> people load it to the brim. Adding a grate and filling the existing volume
>> with stones prevents that people can land the same amount of charcoal as
>> the stones displace the charcoal.
>>
> *[RWL4:   Are you suggesting the stones make no sense?    Kevin is doing
> stones in this thread because they were giving a roughly
> 50% efficiency improvement with 3-stone wood fires.  They are placed before
> the charcoal - not after.  Explanation not yet clear for wood either.
> Certainly air flows, but there is some energy stored up in the rocks that
> may be helping.  I know of no-one except Kevin testing added (zero cost)
> stones.*
>
> Same as putting a brick in the tank for the toilet flush saves water, as
>> it fills part of the volume.
>>
> *[RWL5:    I doubt this will be proven with further testing.  In any case,
> Kevin displaced no fuel (no fuel saved).  But this also might also argue
> against your above argument that you should lose efficiency.  I think your
> suggestion of a large brick in a Mbaula is also worth testing (and my main
> point is we need more testing).  I haven’t got the foggiest idea whether an
> added brick would make the efficiency go up or down.   *
> * I’ve spent a lot of time recently on the Mbaula.  Despite decades of
> attempts to introduce a better stove - it seems to have 99% of the market,
>   I am amazed and am looking for explanations of that as well.  The first
> obvious answer is that it is cheap.  Crispin said $1.50;  this has to be a
> big part of the answer.   But also, there are no middle men - it is sort of
> like buying vegetables at your local market;  people probably are happier
> knowing 100% of this purchase price stays in the local economy.  And the
> producers are also using scrap steel;  we should be finding ways to do the
> same.*
> *  Lasts maybe a year.  Has no air flow control. (And of course no stones
> or extra grate).  (Yet.)*
>
> * But Kevin’s surprising discoveries of the extremely low cost
> modifications is not limited to the Mbaula.  His first report on charcoals
> [not wood burning - which was earlier] a few weeks ago (to which I also
> responded with a similar plea for more study) had the same big efficiency
> improvements. (Sometimes with only one of the two mods now reported from
> Zambia).  If anyone didn’t read those three earlier (and less detailed)
> reports by People Kevin has hired) - then you should.*
>
>
>> I did testing on the Zambian brazier today (it was loaded with 900 g of
>> charcoal as people tend to fill it up) , and we cooked the same meal with
>> less than half the charcoal on any of the other stoves where we only loaded
>> with an initial 310-350 g of charcoal
>>
> *[RWL6:  You may not understand his testing procedure.  The cooking was
> not done with 1000 gm.  After each test they separated out the unused
> char.  The consumed char results were much less than 300 gm - and this
> net-used-char number went down as they added (first) stones) and (then)
> both stones and a second grate.*
>
> * To repeat - I know of no one else in the stove world reporting on
> positive results from either extra stones or grates.  His testing needs
> support from many of the people going to the Nairobi stove meeting next
> week.  Kevin has paid for these four reports  and others - all (admittedly
> very preliminary) out of his own pocket.   The least we can do is accept
> that the results are new and need more research.  Again - to save trees.  *
> * (And I am working on steering him into the real savings of
> charcoal-making stoves.  We’re working on getting that down to $1.50, with
> skilled stove artisans in the next block.)*
>
> *[RWL:  My last sentence response below to Bernhard said *" *My next
> message more on that)”*.   *Coming ASAP.*
>
> *Ron*
>
>
>> That is my answer
>> Christa
>>
>> Am 30.10.2019 um 19:13 schrieb Ronal Larson <rongretlarson at comcast.net>:
>>
>> Bernhard and list,  cc Kevin
>>
>> 1.  Kevin responded to your increasing CO comment (below) - saying CO not
>> yet measured.   (This following Kevin’s message re adding rocks and an
>> extra grate to the Zambian  (char-burning) “Mbaula” - giving maybe 40% fuel
>> saving.
>> 2.  I guess that the reverse is likely: less CO.   My reason is the
>> horrible production of CO - which drives down efficiency.  Kevin’s
>> efficiency is going up - not down
>>
>> 3.  This is mainly to hope that we can find someone (in nGermany?) to
>> make the measurement.  Important because Kevin is achieving a huge
>> tree-saving result at almost no cost.
>>
>> 4.  We have no idea yet on why simple rocks and extra grates are doing so
>> much.   (Anyone have an idea why?  My next message more on that)
>>
>> Ron
>>
>> Ps - Thanks for all you have done for solar cookers (I own one of your 1
>> meter parabolic designs).  Your BABAMOTO stove (see below) looks quite
>> interesting.  I was happier to read your piece on char-*making* stoves
>> at:
>>
>> https://vignette.wikia.nocookie.net/solarcooking/images/b/b6/Gasifier_Stoves%2C_Bernhard_Muller%2C_3-21-16.pdf/revision/latest?cb=20160322185245
>> <https://vignette.wikia.nocookie.net/solarcooking/images/b/b6/Gasifier_Stoves,_Bernhard_Muller,_3-21-16.pdf/revision/latest?cb=20160322185245>
>>
>>
>>
>> On Oct 27, 2019, at 11:19 AM, Bernhard Müller <bs_mueller at gmx.net wrote:
>>
>> Kevin,
>> the way I understand this system is to obtain efficiency for the price of
>> more CO production.
>> Bernhard S. Müller
>> Mühlstr. 26
>> 65760 Eschborn
>> bs_mueller at gmx.net
>> https://www.babamoto.org
>> https://www.afrishiners.solar
>>
>>
>>
>>
>>
>> Am 27.10.2019 um 18:00 schrieb stoves-request at lists.bioenergylists.org:
>>
>> (no subject) (K McLean)
>>
>>
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