[Stoves] (no subject) (K McLean)
Ronal Larson
rongretlarson at comcast.net
Wed Oct 30 16:45:40 CDT 2019
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 <mailto: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 <mailto: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 <mailto: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 <mailto:bs_mueller at gmx.net>
>> https://www.babamoto.org <https://www.babamoto.org/>
>> https://www.afrishiners.solar <https://www.afrishiners.solar/>
>>
>>
>>
>>
>>
>>> Am 27.10.2019 um 18:00 schrieb stoves-request at lists.bioenergylists.org <mailto:stoves-request at lists.bioenergylists.org>:
>>>
>>> (no subject) (K McLean)
>>
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