STOws Cooker - Low Cost Concrete and Ceramic Stove
by Crispin Pemberton-Pigott (PROBEC)
25 Sept 2006

Design Brief:
The development of a stove for use in low income areas of rural Senegal.

Maputo Ceramic Stove Images August 23, 2006
Crispin Pemberton-Pigott, New Dawn Engineering, August 23, 2006

Crispin has provided us with the following images of his new MCS 200 stove.

MCS 200 Profile ViewMCS 200 Profile View

MCS 200 Top ViewMCS 200 Top View

MCS 200 Top View Grate OutMCS 200 Top View Grate Out

MCS 200 Bottom View No GrateMCS 200 Bottom View No Grate

MCS 200 Bottom View 9 Hole Grate200 Bottom View 8 Web 9 Holes

MCS 200 11 Hole vs 9 HoleMCS 200 11 Hole vs 9 Hole

MCS 200 1150C vs 800CMCS 200 1150C vs 800C

MCS 200 1160 Hold vs 1150MCS 200 1160 Hold vs 1150
MCS 200 - 2 After 2 Hr Test BurnMCS 200 - 2 After 2 Hr Test Burn

Note: Click images to enlarge

Glazed Maputo Ceramic Stove
Crispin Pemberton-Pigott, New Dawn Engineering, August 23, 2006

Glazed Maputo Ceramic StoveGlazed Maputo Ceramic Stove

Click to enlarge image

Dear Friends

This is a picture of a glazed MCS 200 (200 mm in diameter) which was made this week in Maputo.

The idea is that the stove should not look 'like a ceramic stove' but more like a casserole or a serving dish, something perhaps one would find in a kitchen rather than out in a shed.

First test of the Maputo Ceramic Stove
Crispin Pemberton-Pigott, New Dawn Engineering, August 20, 2006


Note: click image to enlarge.

Dear Friends

I have completed a test of the first fully formed Maputo Ceramic Stove (MCS) with 3 litres of water and initially a bit more than 300 gm of charcoal. The unit in the pictures is the final version.

The test was done without any skirt or under-tray to improve efficiency, just a pot and lid sitting on a simple stove.

The water boiled in exactly 30 minutes even though the stove body was wet from being washed (oops).

The specific fuel consumption calculated on the basis of water remaining at the time of boiling (good idea) and water remaining at the end of the simmer (something I think is weird) is:

48 gm per litre of water boiled
16.5 gm per litre simmered at 1 degree below the local boiling point for 45 minutes.

This translates into about 324 gm to boil and simmer 5 litres of water, depending on how you calculate it.

The stove was easy to use. I closed the air hole when it boiled and otherwise did not touch anything at any time.

There was more than 140 gm of charcoal left in the stove at the end of the test. This means it had too much in it to begin with. I was unable to get the temperature to drop below almost the boiling point so I think if it was done again with perhaps 200 or 250 gm of fuel it would come out with a better figure.

The stove in the photos will cost about $3 to manufacture profitably. The material is very low thermal expansion PK11 clay mix fired at 1150 degrees. The whole stove weighs 2230 grammes. The material cost about US$0.40. The grate is removable. The two parts can be formed in a manual press like the Ring Maker.

Maputo Ceramic Stove - 2 samples fired differently
Crispin Pemberton-Pigott, New Dawn Engineering, Swaziland, August 18, 2006

Dear Clay Stove Makers

I am forwarding a photo of two Maputo Ceramic Stoves (MCS) without a grate. One was fired by a thumb-suck method and the other was fired in an oven with a temperature controller.

One of the things I have found is that there is more confidence in the ceramic industry than knowledge.

The two stoves are exactly the same, made from PK11 which is a high feldspar clay, the greater portion being black plastic clay.

You will notice that the darker of the two has a shiny appearance. This is from the melting of the minerals. Looking closely you can see small pock-marks which is where the powdered charcoal burned out (about 10% by weight).

The lighter one is powdery when touched, much lower tone when struck and significantly weaker. The only difference between the two is the firing temperature.

Sample Ring From the Ring Maker
Crispin Pemberton-Pigott, New dawn Engineering, July 30, 2006

Sample Ring From the Ring MakerSample Ring From the Ring Maker

Improved Mali Stove
Crispin Pemberton-Pigott, New Dawn Engineering, July 21, 2006

Dear Friends

I have heard confirmation from FASEN in Dakar (Senegal) that the women cooking at the ProBEC head office are using 50% less charcoal with their 'improved Malgach' stove (pronounced mal-gash).


We know this as the garden variety Mali stove - a very simple metal, inverted, truncated pyramid sitting on a square stand with one side missing attached to a flat, square base. There are millions of them all over Africa.

We added a door to close the open side in the stand, and another truncated, inverted pyramid to the top, creating a counter-flow air preheater. The air now only enters from below when it is being lit. There are two bricks in the base to contain heat from the grate and pass it to the incoming air.

The charcoal is loaded in the usual way and lit. A metal rod bent into a triangle is dropped in and a square sheet with a pot skirt is then dropped on top of everything, closing in the fire. The rod keeps the pot off the charcoal - preferably a 50mm gap.

The fact that the women are putting in 1/2 the charcoal normally used is not the end of the story. The stove is designed for 2 kg of charcoal so putting in 1 kg is leaves empty space. In reality the stove could be reduced in size by 30% in length, breadth and height reducing the material cost to approximately that of the original, larger, more wasteful stove. The gap between the two 'pyramids' is 13 to 16mm.

Big Improvements For Small Cooking Stoves: The Benefits of Heat Recycling
Crispin Pemberton-Pigott, New Dawn Engineering, January 2004

ETHOS CONFERENCE 31 Jan to 1 Feb 2004

These days so much is known about combustion that efficient and nearly complete
combustion can be basically taken for granted, even if the knowledge has not been put into
practice. Combustion geeks now focus to making incremental improvements in the removal
of unwanted combustion products, largely PICs and CO.

Crispin Pemberton-Pigott, New Dawn Engineering, Swaziland, June 12, 2006

3 Laterit and Charcoal Dust3 Laterit and Charcoal Dust

Dear Friends

I fired two of the rings today for a brief time, perhaps 3 hours at temperature. No particular care was taken regarding the slow initial temperature rise.

Crispin Pemberton-Pigott, New Dawn Engineering, June 3, 2006


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