[Stoves] Stoves Digest, Vol 111, Issue 11
Norman Baker
ntbakerphd at gmail.com
Mon Nov 11 12:06:12 CST 2019
Everyone;
I think Kirk's explanation of the three stone fire is right on target. I
have done similar small experiments in my woodstove trying to elevate
firewood above the floor of the stove. Iron cradles designed to hold
firewood seem to steal too much heat. Now instead of all the firewood being
in a stack of parallel pieces, I build a woodstove fire like you are doing
a conservation burn to make biochar. Stack the pieces at 90° to each other
for each layer. My woodstove reaches operating temperature much quicker and
it is very clear getting air down into the base of the fire is important.
Norm
On Mon, Nov 11, 2019 at 10:01 AM <stoves-request at lists.bioenergylists.org>
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> 1. Fwd: Re: Improving cooking with charcoal (Harris, Kirk)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 11 Nov 2019 09:34:10 -0800
> From: "Harris, Kirk" <gkharris316 at comcast.net>
> To: Discussion of biomass cooking stoves
> <stoves at lists.bioenergylists.org>
> Subject: [Stoves] Fwd: Re: Improving cooking with charcoal
> Message-ID: <5c89f3af-b48f-9dad-908d-d259d9cc7e89 at comcast.net>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
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>
> -------- Forwarded Message --------
> Subject: Re: [Stoves] Improving cooking with charcoal
> Date: Sun, 3 Nov 2019 09:58:43 -0800
> From: Harris, Kirk <gkharris316 at comcast.net>
> To: Discussion of biomass cooking stoves <
> stoves at lists.bioenergylists.org>
>
> Hi All,
>
> I have been thinking further on this question.? The rocks have a very
> small contact surface with the ground, and so the heat flow to the
> ground from the rocks is small.? This means that the rocks will get
> quite hot.? Two things here, the charcoal will be kept hotter then if it
> was on the ground, and the rocks will present considerable surface area
> to the incoming air and so preheat it.? Also the hot coals which fall
> between the rocks will preheat the incoming air.? These may have
> something to do with the improved performance of the rock bed. Also, the
> char which falls to the ground between the rocks will produce CO, which
> has air to burn just below and directly inside the charcoal fuel stack,
> helping to keep it very hot.? There may be other advantageous chemical
> reactions which have to do with reduction, or the interaction of water
> vapor, which I know very little about.? Perhaps some or you, like maybe
> Crispin, could help with this question.
>
> Kirk H.
>
>
> Hi All,
>
> *"We?still don?t have an explanation why."*
>
> I'll give it a shot.**Going back to the fire triangle telling us what is
> necessary for a fire, we need fuel, oxygen, and heat.? I also like to
> add mixing and time because fuel and oxygen cannot burn if they don't
> come into contact with each other (mixing), and chemical reactions take
> some time to occur.? Which of these is being effected by the stones??
> Certainly there is more oxygen because air is able to pass between the
> stones to feed the fire from below.? A fire on a solid surface may loose
> heat to that surface, and the stones would reduce that surface, keeping
> more heat in the fire.? Char may fall between the stones giving more
> surface area for burning, increasing mixing.? All of these could
> increase the heat, keeping a flame burning above the charcoal, unless
> the cooking vessel is placed directly on the charcoal, which would
> extinguish the flame.? If there is a CO flame above the charcoal then
> the CO, which is a flammable fuel, will be burned, eliminating it from
> the exhaust, and increasing the available cooking heat.
>
> Kirk H.
>
> *
> *
>
> On 11/3/2019 7:59 AM, Ronal Larson wrote:
> > Liat, ?Kevin, Crispin
> >
> > See inserts.
> >
> >> On Nov 3, 2019, at 6:12 AM, K McLean <info at sun24.solar
> >> <mailto:info at sun24.solar>> wrote:
> >>
> >> Regardless of the pros and cons of making and cooking with charcoal,
> >> charcoal will be used for cooking by many, many people for decades to
> >> come.? Isn't the vast majority of charcoal produced in the same dirty
> >> way it was produced a fifty years ago?? And doesn't the vast majority
> >> cook with charcoal essentially the same way as fifty years
> >> ago???Let's find more methods to improve both production and usage,
> >> methods that people will readily adopt.? Kevin
> >>
> > *[RWL1: ?I agree with all. ?I hope the emphasis in this thread can
> > only be on usage (see thread name -??Improving cooking with
> > charcoal?). ? So below, ?I excise everything except Kevin?s surprising
> > announcement from four countries ?(Zambia, ?Sierra Leone, Uganda,
> > Kenya) ]that adding rocks and extra grates (no cost?and low cost
> > respectively) apparently gave MUCH (>40%) improved cooking
> > performance. ? We?still don?t have an explanation why. ?Kevin is doing
> > more tests. ?Can anyone else help with trying to optimize these two
> > new stove ideas?*
> > *
> > *
> > *(more below - also from today)
> > *
> >> /
> >> /
> >>
> >> On Sun, Nov 3, 2019 at 7:42 AM Crispin Pemberton-Pigott
> >> <crispinpigott at outlook.com <mailto:crispinpigott at outlook.com>> wrote:
> >>
> >> Dear Friends
> >>
> >> I like the discussion about what to test for, and what to
> >> measure, and how, and where results should lead.? It has been a
> >> long time since an open discussion was held. We have had years of
> >> advocacy for a particular method, not what is needed leading to a
> >> test designed to do that.
> >>
> > *[RWL2: ?Not sure of the intent here, but I am advocating against
> > controlled cooking tests. We must use the water boiling test to be
> > able to compare across stove types with and without stones and extra
> > grates.*
> >>
> >> Charcoal stoves have many advantages over wood stoves, including
> >> benefits of the char as an energy carrier. It is light, easily
> >> dried, and doesn?t rot.
> >>
> > *[RWL3: ? Yes, char is light, but per unit volume, most biomass is
> > superior. ?You can put more megajoules via wood into any of the 4
> > char-burners that Kevin has introduced than you?can via char. ?Volumes
> > can be as important as weight. ?The big advantage of a wood stove over
> > a char-using stove is that the wood (or other combustibles) can be
> > turned into biochar - see next.*
> >>
> >> It is relatively easily ignited. The fact that people crate char
> >> wastefully and burn it inefficiently and incompletely is not an
> >> attribute of the fuel but of the managers.
> >>
> > *[RWL4: ?Agree in part on?charcoal stove advantages. ?I think a main
> > one is that, once lit, they don?t need the attending that most wood
> > stoves do. (TLUDS don?t need much tending). ? I am torn on supporting
> > Kevin in studying?rocks and grates,?because the production is so bad
> > (Kevin?s#1 point above), and because the charcoal can be so important
> > when treated as biochar (dozens of advantages - but?mainly energy,
> > climate and food). ?But I agree with all of Kevin?s points above -
> > ?ethically we should all be trying to make the horrible practice of
> > cooking with charcoal as less evil as we can*.*Cooking while making
> > char is a good topic as well - but not in this thread.*
> >>
> >> While it is popular to say that charcoal makes ?a lot of smoke?
> >> when it is made, it is only true when people do that, and not
> >> when they don?t.
> >>
> > *[RWL5: ?Like Kevin - I worry a lot about how it is made - but
> > production is not the theme of this thread*
> >>
> >> Some of the best users of charcoal fuel are cooks in Cambodia.
> >> They are effective and frugal and have been doing it for
> >> thousands of years. Maybe we can learn something from them.
> >>
> > *[RWL6: ?Cambodia could be appropriate - especially if they can tell
> > us anything about using rocks or extra grates. A cite on Cambodian
> > charcoal being more efficient in usage? ?No need for a cite in this
> > thread on char production - even via TLUDs.*
> > *
> > *
> > *Ron
> > *
> >>
> >> Regards
> >>
> >> Crispin
> >>
> >> *From:*Ronal Larson <rongretlarson at comcast.net
> >> <mailto:rongretlarson at comcast.net>>
> >> *Sent:* Wednesday, October 30, 2019 19:14
> >> *To:* Discussion of biomass cooking stoves
> >> <stoves at lists.bioenergylists.org
> >> <mailto:stoves at lists.bioenergylists.org>>; Crispin
> >> Pemberton-Pigott <crispinpigott at outlook.com
> >> <mailto:crispinpigott at outlook.com>>; Kevin McLean >
> >> <info at sun24.solar <mailto:info at sun24.solar>>
> >> *Cc:* Christa Roth <stoves at foodandfuel.info
> >> <mailto:stoves at foodandfuel.info>>
> >> *Subject:* Improving cooking with charcoal
> >>
> >> Crispin, Kevin, ?List, ?cc Christa
> >>
> >> Note change in thread title. ? The previous were under the name
> >> ?no subject?- which wouldn?t help researchers not around for this
> >> thread (which is going well).
> >>
> > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?<snip a lot>
> >>
> >> *From:*info at sun24.solar <mailto:info at sun24.solar>
> >>
> >> *Sent:*October 27, 2019 9:01 AM
> >>
> >> *To:*stoves at lists.bioenergylists.org
> >> <mailto:stoves at lists.bioenergylists.org>
> >>
> >> *Reply to:*stoves at lists.bioenergylists.org
> >> <mailto:stoves at lists.bioenergylists.org>
> >>
> >> *Subject:*Re: [Stoves] (no subject)
> >>
> >> Here is areport from Zambia
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.google.com%2Fdocument%2Fd%2F167i50oweyfe23bRMnDSeJwlu0eM4IgTek6IO2C6JPes%2Fedit%3Fusp%3Dsharing&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148782634&sdata=50qonsQ30NwtTdhm1UFaoLnAnRAE3hq0ZQWg%2FFARzJI%3D&reserved=0
> >indicating
> >> that the rock bed and second metal grate improve the
> >> efficiency of the Zambian mbaula (all-metal) charcoal jiko by
> >> 41%.? Cooking time is also greatly reduced.? While these
> >> testers have no training, their results are consistent.
> >>
> >> This is such a simple modification that dissemination could
> >> be very rapid.? I hope some of you can try this.
> >>
> >> On Thu, Oct 10, 2019 at 1:37 PM K McLean <info at sun24.solar
> >> <mailto:info at sun24.solar>> wrote:
> >>
> >> Listmates,
> >>
> >> Has anyone tried this?
> >>
> >> We seem to have significantly increased the efficiency of
> >> charcoal jikos by putting a bed of rocks on the jiko's
> >> grate and putting second metal grate on the rock bed.?
> >> The charcoal goes on the second metal grate. ?2-3 cm
> >> rocks work. It works in all metal jikos and clay jikos
> >> that we've tested.
> >>
> >> Our testing is early and unscientific, but consistent.?
> >> 25-50% less fuel used.? Here are three reports. The
> >> Sierra Leone report has good photos at the bottom.
> >>
> >> Sierra Leone
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Ffile%2Fd%2F12MvBKjxq6PCGCcCHAjSYSeVXXvl7jWjD%2Fview%3Fusp%3Dsharing&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148782634&sdata=QUKUqFK7%2BSRPyu3kcVSZDJR6QIz%2FNVrYFJNOruqRPl0%3D&reserved=0
> >
> >>
> >> Uganda
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Fopen%3Fid%3D1zQIY49E1vrfjYl7t5V_shvw70d67QirGWUrbW51tDxo&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148792643&sdata=gcU31g2xkNP6CvATAaOYiagHuLr2AotChRIUHTkSBTQ%3D&reserved=0
> >
> >>
> >> Kenya (very few rocks)
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdrive.google.com%2Fopen%3Fid%3D1MPwHCwKEVqJvuybKB5Yj39nr8fbcopBP&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148802651&sdata=4REjkNM%2BzaufoOuOIuT%2BDcnQE%2BH7FYfljlHg6K3dRlY%3D&reserved=0
> >
> >>
> >> (The report authors are untrained and not native English
> >> speakers. Especially the Kenya report contains many
> >> errors. Please focus on the consistent final conclusion
> >> that a rock bed and second metal grate significantly
> >> reduce firewood usage.)
> >>
> >> This may be a very low cost, very easy way to greatly
> >> improved the efficiency of charcoal jikos.? I'd like to
> >> hear if there is already a body of work on this.? Here is
> >> my rough drawing:
> >>
> >> <20191010_133359.jpg>
> >>
> >> Thank you,
> >>
> >> Kevin
> >>
> >> /Kevin McLean, President/
> >>
> >> /Sun24/
> >>
> >> /https://sun24.solar
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsun24.solar&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148802651&sdata=M6yOWdYV2B5YCSb%2BybnechSugQGGY5HLCoES1dZyiBM%3D&reserved=0
> >
> >> Sun24 Cookstoves Overview
> >> <
> https://eur04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.google.com%2Fdocument%2Fd%2F1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y%2Fedit%3Fusp%3Dsharing&data=02%7C01%7C%7Cd9ec2f74d13049f204fa08d75d8ec8b4%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637080740148812660&sdata=6ZBNIMFoA9ti4uGqy9RZTpJGCNUzcH18%2BgZ%2Bx93rgcE%3D&reserved=0
> >/
> >>
> >> /Tampa, Florida, USA/
> >>
> >> /+1 (813) 505-3340 <tel:+1(813)5053340>/
> >>
> >
> >
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