[Stoves] Rocket stove video two with bevel

Mon Oct 23 13:52:37 CDT 2023

Dear Friends

Further to the messages containing the two videos.  Apparently the first one was captured by the oversize rule and sent to Andrew who forwarded it.  When I tried to view it in the message, I was informed that I needed a CODEC to view it.  If this happened to you, save it to disk and view it with any of a variety of programmes.

There are three generic improvements that you can incorporate into your rocket stove.

  1.  Install a grate of some kind with an air flow roughly 1/6 of the total of the fuel opening plus the grate opening. The air should not come under the fuel, especially on a fire frame, it should come up from below or behind.  In general there is too much air entering with the fuel so if you reduce the height in reduce the area  by 20%, you then add that much to the grate or the opening leading to the grate.
  2.  Trim the last brick where the horizontal air enters the combustion chamber.  It can be cut at 45 degrees.  In the example shown in the video is about ½ the height of the fuel channel.  If the channel is 200mm, the cut is from 100 back and 100 up.
  3.  The pot has 4 strips of metal welded onto the pot.  The size and position of these has not been announced yet. It is the result of optimisation that is still a work in progress, however one was built and tested at a school in Kigali, Rwanda in September.  This change, adding strips, improved the thermal efficiency about 7% from 52% to ~60%.  It causes the gases to rotate horizontally (generally) and heats the cold spot typically seen at the front top of a chimney stove.  This solution is generic, meaning it applies to any stove that has a central heating source and a chimney on one side.

I will create a 3D Rocket Stove model and run the same simulation and share it so readers can see the problems addressed by the solutions above.

There is, as I said, a heat diffuser plate above the centre of the fire that causes the bottom of the pot to be heated evenly enough that when it is boiling, it can be seen through the water than it is boiling everywhere on the bottom, not concentrated in the centre.  This avoids burning food in the middle - a serious and costly problem for schools.

[cid:image002.jpg at 01DA05AF.46E29100]

The perforations in the plate pass ~15% of the total heat to the pot centre - though I can't prove that at the moment.  Doing so will require making some heat flux measurements on the inside of the pot surface.

I didn't give any reference to the size of this stove.  To give you an idea about its performance, it can boil 100 litres of water per 17 minutes with a maximum heat gain rate of 39 kW, typically 34 kW in the pot at high power.  It can cook 100 kg of rice in just under an hour without burning any of it.  The cooks are delighted.

Additional models are being prepared from 50 to 500 litres.

Stay well everyone
Crispin

Crispin Pemberton-Pigott

New Dawn Engineering Inc.
P.O. Box 3
Alberta Beach, Alberta
Canada T0E 0A0
www.newdawnengineering.com<http://www.newdawnengineering.com/>
APEGA Permit 16026

Research & Design Office
5011 Crestview Drive
Val Quentin , Alberta
Canada, T0E 0A0

Email: crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>

From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of Crispin Pemberton-Pigott
Sent: Monday, October 23, 2023 10:37 AM
To: Ronal Larson <rongretlarson at comcast.net>; stoves at lists.bioenergylists.org
Subject: Re: [Stoves] Rocket stove video two with bevel

Dear Ron

There were supposed to be two videos. The one with no message is the second one. Did the first come through? I didn't see it.

There was a long explanation about what to look for.

Thanks
Crispin
________________________________
From: Ronal Larson <rongretlarson at comcast.net<mailto:rongretlarson at comcast.net>>
Sent: Monday, October 23, 2023 9:10:48 AM
To: stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org> <stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>>
Cc: Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>>
Subject: Re: [Stoves] Rocket stove video two with bevel

List and Crispin

   Beautiful.

   How can we get same for a TLUD?

Ron

> On Oct 22, 2023, at 11:16 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>> wrote:
>
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