[Stoves] Rocket stove fuel channel

[K McLean]

Yes, I can open Kabuna 4.0 with square corner.mp4

On Wed, Oct 25, 2023 at 9:52 AM Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Kevin
>
>
>
> A couple of people have had trouble opening the .mov file.  I have
> attached an MP4 version so you can see it.
>
>
>
> Let’s get on the same page first.  Video 1 is the square cornered
> combustion entrance.  Can you open it?
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
> *From:* Stoves <stoves-bounces at lists.bioenergylists.org> *On Behalf Of *K
> McLean
> *Sent:* Tuesday, October 24, 2023 8:11 AM
> *To:* Discussion of biomass cooking stoves <
> stoves at lists.bioenergylists.org>
> *Subject:* Re: [Stoves] Rocket stove fuel channel
>
>
>
> Crispin,
>
>
>
> I cannot open the videos so I don't have a full understanding of your
> stove. Tier 5 is impressive.
>
>
>
> Can adding a second burner in front of the stove help?  This video
> <https://drive.google.com/file/d/1EJQEKKkMTQbcKn3kBC1YZ50oqtZPsbym/view?usp=sharing>
> shows how we do it with two bricks.
>
>
>
> Kevin
>
>
>
> On Mon, Oct 23, 2023 at 11:47 PM Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
> Dear Friends
>
>
>
> I have been working with some simulations of heat and gas flow through a
> Rocket Stove-like structure and have a couple of suggestions.
>
>
>
> They relate to three of the downsides of the classic rocket layout, namely
> the absence of a grate, the tendency of the flames to run up the back wall
> and when a chimney is fitted, the tendency of the chimney to pull the
> hottest gases to one side (the back) where heat is already concentrated.
> This leaves the front of the pot relatively cold.
>
>
>
> Recently I have measured stack temperatures as high as 680 C at the exit
> from the stove body (which was a Muvero sunken pot large stove).
>
>
>
> I am sending two videos separately because of the size. The first shows a
> typical channel layout but with three changes from the classic pattern. 1)
> There is a primary air supply under the fire chamber provided through 25
> holes. 2) There is a perforated diffuser plate under the pot distributing
> the hot gases pretty evenly across the bottom surface. 3) The pot is
> modified on the outside to prevent direct access to the chimney so the
> gases are forced to go round the pot body.
>
>
>
> Apart from these modifications the hot gas flow into the fire chamber is
> standard as the other changes only affect what happens after that.
>
>
>
> In the second video the last brick crossing the top of the fuel channel is
> cut away at 45 degrees. Note the difference between the two routes taken by
> the hot gas when in a state of thermal equilibrium.
>
>
>
> I will prefer that some of the primary air enters from the back but it
> happens that the setup we have for building them is complex enough without
> adding a second grate with different dimensions. That flow could in theory
> put the flames in the centre, front-to-back.
>
>
>
> There is an ash clean out channel passing from the box under the grate but
> it is not shown. At the end of it is a primary air entrance hole.
>
>
>
> What you see is the hot gas flowing, with none of the stove shown. What
> you see as "shape" is actually the volume within the stove body.
>
>
>
> It is very easy to add this 45 degree cut and it definitely improves the
> gas flow keeping it largely off the back wall.
>
>
>
> The efficiency of this stove, considering high and low power, is just
> about 60%. For efficiency, PM and CO it is ISO Tier 5 when burning 14%
> moisture *eucalyptus grandis*.
>
>
>
> Best regards
>
> Crispin
>
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