[Stoves] Ash mixed with clay to mud in brick stoves

[K McLean]

Thanks, Crispin,

You advice fits nicely into my overarching principle:  "Keep it simple,
stupid."

The bricks will be made out of whatever material is used locally,
invariably high mass.  The insulative mud is only a thin veneer spread onto
the bricks by the women.

If I understand you correctly, wouldn't it be advantageous to mud the
exterior but not the interior.  That would allow the bricks to quickly
absorb heat, release less heat to the outside and therefore give back more
of the invested heat to the fire chamber?

The dung/char test won't work without modification as this stove is only
designed to burn wood.

Kevin

*Kevin McLean, President*
*Sun24*

*https://sun24.solar <https://sun24.solar>*
*Tampa, Florida, USA*
*+1 (813) 505-3340*






On Fri, Aug 17, 2018 at 6:45 PM Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Kevin
>
>
>
> Mud is quite insulative without adding anything. Before assuming
> *anything* please check to see if there is some advantage to having a
> lower density stove body (which will definitely be physically weaker)
> before recommending it. Make sure the amount of new fuel required to
> perform some task is consistently less before assuming it is “better” in
> some way.
>
>
>
> Many tests have shown that on average, a high density combustor core
> outperforms “insulative” chambers unless the cooking time is very short.
> The reason is that heat must emerge from the walls at a high rate during
> the late fire cooling period. If this effect is achieved, the CO burns out
> more completely, the invested heat (some of it) is returned) and the char
> burns more completely.
>
>
>
> If the stove body is ‘insulating’ the gain in thermal efficiency is brief
> and only at the beginning, give or take a few Watts. Unfortunately an
> insulating body, even if it contains a large amount of invested heat,
> cannot give it back to the fire chamber at a rate high enough to sustain
> the combustion as late or as long. Depending on the stove configuration,
> the efficiency gain for having a high density combustion chamber is about
> 1/12th of value which is considerable: 26% v.s. 24%, for example.
>
>
>
> When burning dung the effect is far more noticeable to the eye, without
> measuring anything. The thing to check is how much ‘char’ there is in the
> large lumps of ash when the fire is out. Using a high mass, dense brick
> lining for the chamber, it is possible to get dung to burn so completely
> that you will not find more than one piece of char the size of a pea after
> burning 5 kg of fuel. All that is left is a fine white ash.
>
>
>
> An example (including all drawings) of such a stove is available here
> <http://www.newdawnengineering.com/website/library/Stoves/Kyrgyzstan/KG%20Model2.5/>
> .
>
>
>
> Regards
>
> Crispin
>
>
>
> *From:* Stoves <stoves-bounces at lists.bioenergylists.org> *On Behalf Of *K
> McLean
> *Sent:* Friday, August 17, 2018 2:05 PM
> *To:* stoves at lists.bioenergylists.org
> *Subject:* [Stoves] Ash mixed with clay to mud in brick stoves
>
>
>
> In Africa, we are teaching women to make rocket stoves out of 11 standard
> bricks and a piece of rebar.  You can see it here, called a 3-layer stove:
> https://docs.google.com/document/d/1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y/edit?usp=sharing
> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdocs.google.com%2Fdocument%2Fd%2F1ZryS7gQ1q3zKLZPM2KcXdtIHbOYQp4PbloPqMvrlZ5Y%2Fedit%3Fusp%3Dsharing&data=02%7C01%7C%7Cf927dbb0d7754fd5fc1808d6046c458f%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701260400084277&sdata=q3ZC6QPL34O6NXpg%2FqzGd5yz7Aj%2B%2BA64aN7AZ4YvyQw%3D&reserved=0>
>
>
>
> Do any of you have experience mixing wood ash with clay soil to make the
> "mud" more insulative?  The women like to mud in these stoves.  We want to
> determine whether to suggest they mix ash into the mud.
>
>
>
> Thank you,
>
> Kevin
>
>
>
> *Kevin McLean, President*
>
> *Sun24*
>
> *https://sun24.solar
> <https://nam02.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsun24.solar&data=02%7C01%7C%7Cf927dbb0d7754fd5fc1808d6046c458f%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C636701260400084277&sdata=h9jZkm7w837YU3VnK7bQX%2BGLgGlD5dSBX07TX7YYLrU%3D&reserved=0>*
>
> *Tampa, Florida, USA*
>
> *+1 (813) 505-3340*
>
> *info at sun24.solar <info at sun24.solar>*
>
>
>
>
>
>
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