Maputo Ceramic Stove

The results of field testing the POCA/Maputo Ceramic Stove (MCS) and traditional metal stoves (TMS) using an uncontrolled cooking test (UCT) are attached. In a UCT people cook whatever they want and we watch carefully. The results have fuel-moisture compensated values. The charcoal was almost always hardwood lumps. Larger meals tend to be watery and small meals tend to be frying something in oil.

The comparison indicates a clear change in relative performance with meal size. The bigger the meal, the more the savings with the improved stove. There is also a chart attached showing the increase in thermal efficiency with meal size.

The meal size on one the X-axis.

The WBT locates one point on the line. Performing the test seven times locates that point very accurately but is it difficult to know where the line goes from that point.

No ‘outliers’ were removed in this analysis even when they were obvious. The meal size varies with the season so the question about consumption has more than one answer.

Regards
Crispin
Nike Air Max 720

Crispin Pemberton‐Pigott October, 2008
Sustainable Energy Technology and Research Centre University of Johannesbrg 
Programme for Basic Energy Conservation GTZ/ProBEC a SADC Regional Project 

See the attached pdf: CERAMIC DEVELOPMENT FOR DOMESTIC STOVES 

Also take a look at Crispin's very good ceramic stove image galleries.

It is intended that this brief report describe in an accessible manner the results of some basic research into the performance of ceramic materials suitable for use to make modern, low‐cost improved charcoal stoves. The 
theatre of investigation is the area around Maputo, Moçambique. 

 The information and ideas are assembled from a large number of tests and reports. If studied carefully an understanding can be gained of the 
principle ingredients found in typical clays. It is hoped enough can also
 be learned about what the tests show so as to interest the ‘stover’ in a 
deeper study of this vast subject.  

Some reasons why clay stoves and stove components typically have such a 
short life are described and to a certain extent, what can be done about 
it.   

There is a great deal of material available on how to find, identify and 
process clays such as pottery books and the internet. It is not repeated 
here.  Unfortunately very little of the material available is geared to 
the design of low cost ceramics stoves which have problems not encountered
 in many industrial applications with far higher temperatures.  

Ceramics are complex mixtures of many minerals so it is not possible to 
give comprehensive explanations in such a brief text, however the novice 
reader should learn enough to be able to deal with a laboratory and 
understand some common terminology and the test results.  There have been
 many technological advances in recent years making accessible tests and 
analyses that were previously unaffordable to the ordinary potter.

Maputo Ceramic Stove Update
Crispin Pemberton Pigott, New Dawn Engineering, Swaziland, June 6, 2007
MCSMCS

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

MCS200MCS200

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.

Joao's Clay Vesto Stove - Maputo
Crispin Pemberton-Pigott, New Dawn Engineering, Swaziland, May 2006
Joao da Conceicao

Joao's Clay Vesto
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