[Stoves] Stoves Digest, Vol 146, Issue 11

Sat Oct 22 12:49:26 CDT 2022

Kevin;

Crispin has some really good ideas. That said, the band arrangement is
beginning to look like an evolution toward a TLUD or perhaps a rocket
stove. What might work best is a combination of the operation principles of
a TLUD and a rocket stove. Perhaps you could use a 5 gallon metal bucket
with holes in the bottom and the maize stocks inserted vertically until the
bucket is full. Support the bucket on bricks and use the top of the bucket
to somehow support a cooking pot. If a bucket is used, it would be
relatively easy to retain the biochar and dump it into something for
quenching or urine application. And, an additional bucket could be easily
replaced with a full fresh set of maize stalks for continued cooking. If
your field research supports these ideas, I can easily put together an
arrangement for testing at Aprovecho.

I'm not sure I support a circular arrangement of bricks as the basic
stove. In my work with TLUDs, I find masonry absorbs a lot of the heat and
actually cools the cooking fire and increases the smoke. But, field
research is the only way to document what is actually
happening. Thermocouples and thermocouple readers are easily available on
the Internet and could be used to test temperatures at several points in
your stove. They are actually becoming reasonably inexpensive.

Norm

On Sat, Oct 22, 2022 at 10:04 AM <stoves-request at lists.bioenergylists.org>
wrote:

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> Today's Topics:
>
>    1. Re: Cooking bands - Testing with wood - 42% more efficient
>       than three stone (K McLean)
>    2. Re: Cooking bands - Testing with wood - 42% more efficient
>       than three stone (Crispin Pemberton-Pigott)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 22 Oct 2022 00:14:28 +0200
> From: K McLean <kmclean56 at gmail.com>
> To: ajheggie at gmail.com,  Discussion of biomass cooking stoves
>         <stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] Cooking bands - Testing with wood - 42% more
>         efficient than three stone
> Message-ID:
>         <CALxcr-v-+ehA28b3J8U2Fb2977B-aDfBudT0=LBbJUrNtAOe=
> A at mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> I don't think I shared this video <https://youtu.be/5M4ntJi_JmY> with this
> list.  Some of the same principles are probably at play. This is a
> comparison of two piles of maize stalks.  The traditional way of burning
> maize stalks in Africa is by lighting the pile on the side, as was done
> with the pile on the left.  The pile on the right was lit on the top.  The
> difference in smoke is stunning.
>
> On Fri, Oct 21, 2022 at 5:36 PM <ajheggie at gmail.com> wrote:
>
> > Good stuff Kevin, this must be a similar combustion to a Swedish Candle,
> a
> > short section of trunk with multuple saw cuts axially toward the bottom.
> >
> > Andrew
> >
> > On Fri, 21 Oct 2022 at 11:00, Kevin McLean <kevin at sun24.org> wrote:
> >
> >> Our testing shows that cooking bands boil water with 42% less wood than
> a
> >> three stone cookstove with a rock bed.  Remember that rock beds make
> three
> >> stone cookstoves a third more efficient and reduce smoke by more than
> >> half.  Here is that article
> >> <https://www.sciencedirect.com/science/article/pii/S0973082620302775>.
> >>
> >> THREE STONE W ROCK BED
> >>
> >> 5 litres of water
> >>
> >> Time at which water boiled: 23 minutes.
> >>
> >> Fuel used: 1.2kg.
> >>
> >>
> >> BAND
> >>
> >> 5 litres of water.
> >>
> >> Time at which water boiled: 15 minutes.
> >>
> >> Fuel used: 700g.
> >>
> >> Much less smoky than three stone with rock bed
> >>
> >>
> >> Cooking bands are also faster and less smoky.  They do not require
> >> tending.  Elephant grass stalks, maize stalks, bamboo and cassava stems
> can
> >> be used in bands.  Biochar can be made.  A pair of bands (20 cm) costs
> >> around 1 USD.  Bands with a 25 cm diameter work well in school kitchens.
> >>
> >> I hope that others can test further.  I worry that my guys may bring
> bias
> >> into their testing.  And they have no training on testing.  (Thanks to
> Norm
> >> Baker who intends to test bands with maize stalks.)
> >>
> >> Kevin McLean
> >> Sun24.org
> >> _______________________________________________
> >> Stoves mailing list
> >>
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> >>
> >>
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> >>
> >> for more Biomass Cooking Stoves,  News and Information see our web site:
> >> http://stoves.bioenergylists.org/
> >>
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> >
> >
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> ------------------------------
>
> Message: 2
> Date: Fri, 21 Oct 2022 22:40:32 +0000
> From: Crispin Pemberton-Pigott <crispinpigott at outlook.com>
> To: Discussion of biomass cooking stoves
>         <stoves at lists.bioenergylists.org>, "ajheggie at gmail.com"
>         <ajheggie at gmail.com>
> Subject: Re: [Stoves] Cooking bands - Testing with wood - 42% more
>         efficient than three stone
> Message-ID:
>         <
> MW4P223MB0562D1C0B68665CB162B11CAB12D9 at MW4P223MB0562.NAMP223.PROD.OUTLOOK.COM
> >
>
> Content-Type: text/plain; charset="us-ascii"
>
> Dear Kevin
>
> I have had a look at all the videos and this looks promising.
>
> I admit I cringe when I see obvious improvements that can be made with
> little effort so I will jump in with more advice.
>
> The bands could be made in a way so they do not sit on the ground, or
> three bricks could protrude inwards so the ring sits on them. The idea is
> to get air under the ring towards the end of the fire.  This would increase
> the firepower whereas now it drops quite a lot as the fire goes inside the
> upper part of the ring.
>
> A problem might be created with this change is remnant glowing char on the
> bottom when the replacement fuel charge is pushed in.  I would have on hand
> a flat sheet to use as a scoop to wipe the coals out of that burn space.
>
> On top there is obviously too much cold air getting into the flames which
> it is worth changing.  Instead of stacking bricks for a demo, can you make
> a brick+mud structure that encloses the fire same for an entrance hole
> (liberally bigger than the ring and fuel height)?  Above the ring where you
> push, the bricks can be made into a cylinder (polygon) so that the part of
> the stove now seem above the fuel and flames so there is a cylinder of
> brick. This will shelter the flames from side winds, "through" winds, and
> create a chimney effect.
>
> The chimney effect will draw more ait to the centre, clearly lacking in
> the current version.
>
> It like the ignition in the centre leading to an outward burning set of
> stalks. After it is all going well, the centre is air-starved. The way to
> feed air to the centre is have a relatively small gap above the fuel on the
> near wide, and perhaps two additional holes on the other two thirds. With
> these inlets of restricted size (compared with now) and the chimney effect,
> it should bring jets of air to the centre. What you are looking for as you
> tune the hole and gap sizes is a reduction in the height of the flames.  If
> there is air getting in, the flames will shorten, generally.  Long flames
> are an indication of inadequate air, especially in the centre.
>
> For sure you can build such a brick stove without any mortar at all just
> to see how it works in principle.  If you plan the ring size and brick
> positions, you can create a top deck that will accept the pot bottom with
> something small like a triangle of rebar to create the pot-stove
> clearance.  I suggest 8mm bar to create the clearance.
>
> If the bar diameter is too small, you will see smoke emerging from the
> fuel entrance.  If you get no smoke out the entrance, keep reducing the pot
> rest height until you do, then go up one step. Looking inside the flame
> area, if you see the flames lounging around "reeling like drunkard" instead
> of being drawn up stiffly, and there is no gas emerging from the front, you
> have the perfect balance.  Were you to measure the oxygen level in the
> exhaust past the pot, then calculate the excess air level, you would find
> it is in the range of 125% -250%.  Ideal would be 100%-125% for a simple
> stove. As it is, it is probably 500%-900%.  If you can get it under
> control, it will speed your time to boil.
>
> Stay well
> Crispin
>
> From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of K
> McLean
> Sent: Friday, October 21, 2022 16:14
> To: ajheggie at gmail.com; Discussion of biomass cooking stoves <
> stoves at lists.bioenergylists.org>
> Subject: Re: [Stoves] Cooking bands - Testing with wood - 42% more
> efficient than three stone
>
> I don't think I shared this video<
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fyoutu.be%2F5M4ntJi_JmY&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=QFPdMZwjNaNihFd6ORpQ%2B0zrwouXCdtpi%2Ba3HwTD6rI%3D&reserved=0>
> with this list.  Some of the same principles are probably at play. This is
> a comparison of two piles of maize stalks.  The traditional way of burning
> maize stalks in Africa is by lighting the pile on the side, as was done
> with the pile on the left.  The pile on the right was lit on the top.  The
> difference in smoke is stunning.
>
> On Fri, Oct 21, 2022 at 5:36 PM <ajheggie at gmail.com<mailto:
> ajheggie at gmail.com>> wrote:
> Good stuff Kevin, this must be a similar combustion to a Swedish Candle, a
> short section of trunk with multuple saw cuts axially toward the bottom.
>
> Andrew
>
> On Fri, 21 Oct 2022 at 11:00, Kevin McLean <kevin at sun24.org<mailto:
> kevin at sun24.org>> wrote:
> Our testing shows that cooking bands boil water with 42% less wood than a
> three stone cookstove with a rock bed.  Remember that rock beds make three
> stone cookstoves a third more efficient and reduce smoke by more than
> half.  Here is that article<
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0973082620302775&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=OG1Th8MyiU4IUGZWv%2FDCfokhcsBMTkXgTOoeMRnmNko%3D&reserved=0
> >.
>
>
> THREE STONE W ROCK BED
>
> 5 litres of water
>
> Time at which water boiled: 23 minutes.
>
> Fuel used: 1.2kg.
>
> [
> https://lh3.googleusercontent.com/_euPbO3r0c5l3KczRAbIKflOnO5dIQ2J3s7yldeS8TOfgQszTdpnZYowgJ6NRSuAmR9b3_TPBg3RrK5GH8Qjf2mXq_oZJYy8pGHcb7Q-McDdA7RbtJTLUjkLti1KnSh1L0i3q0Zz7rJkgGChFA0mEXzKSDt0I8518haxVIay7oD1iVg5JtqptU3iNg
> ]
>
>
> BAND
>
> 5 litres of water.
>
> Time at which water boiled: 15 minutes.
>
> Fuel used: 700g.
>
> Much less smoky than three stone with rock bed
>
> [
> https://lh6.googleusercontent.com/VksVVTzfJWB0M5KnWZ6DyJWnFuAjElHzJaPZpTknVT9_S6IiNG0qnnlqdBQf-gllKBmb9MxPxZL3nGARDpoFTTbaTRvYqe-7Or5Txm50R4cuAjIV1rl2__Dv54zN_AM4vcl1PPrFU1WO_RsKroXamkWc_O40Z3ipJZ59cNpKb_UHbYKSjSzw9HrPVA
> ]
>
> Cooking bands are also faster and less smoky.  They do not require
> tending.  Elephant grass stalks, maize stalks, bamboo and cassava stems can
> be used in bands.  Biochar can be made.  A pair of bands (20 cm) costs
> around 1 USD.  Bands with a 25 cm diameter work well in school kitchens.
>
> I hope that others can test further.  I worry that my guys may bring bias
> into their testing.  And they have no training on testing.  (Thanks to Norm
> Baker who intends to test bands with maize stalks.)
>
> Kevin McLean
> Sun24.org
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>
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> >
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/<
> https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstoves.bioenergylists.org%2F&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=HZ0ePK33KnBhBGbAk6OHMXX8Bbl0K7JBOYLbzvIzrrI%3D&reserved=0
> >
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> >
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/<
> https://nam12.safelinks.protection.outlook.com/?url=http%3A%2F%2Fstoves.bioenergylists.org%2F&data=05%7C01%7C%7C86546ca0ee4b446ae3fd08dab3b27779%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C638019876343113197%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=HZ0ePK33KnBhBGbAk6OHMXX8Bbl0K7JBOYLbzvIzrrI%3D&reserved=0
> >
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> ------------------------------
>
> End of Stoves Digest, Vol 146, Issue 11
> ***************************************
>
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