| Boiling Point No. 03 - October 1982 |
The Magan Chula Stove was originated by the All India Village Industrial Association, Maganwadi, Wardha, India, and subsequently improved (in 1955) at the Gandhiniketan Ashram near Madurai, who developed the portable model which we have recently built and tested at Shinfield.
The stove is well established locally and current production is estimated at 100-200 per month by the Ashram potter. We do not know whether the stove is being produced elsewhere. There seems a good chance of it having caught on in the 30 years or so of production. Approximate costs are:
Rs 7.50 18cm diameter stove
Rs 1.00 30cm chimney
Rs 2.50 Chimney cap
It is a ceramic stove which is built, in component sections, by skilled potters and put together in the kitchen then covered with earth. The e earth acts as an insulator and fills any gaps between the pottery sections. This means that the inside of the stove stays hot and the outside stays cooler. As built in India, the stove has pottery or asbestos chimney sections. We used a 7.5cm diameter asbestos chimney, 2 metres high. The stove was briefly described in the ITDG Compendium of Tested Stove resigns (1980). The Percentage Heat Utilised (PHU) was quoted as being 12X for this stove, however, the original ITDG-built model of the stove was copied from inadequate drawings and more recent work has indicated that when built correctly it is capable of up to 22% PHU.
The results of the Shinfield tests are as follows. Initial PHU2 values of 17% were obtained in Standard tests but wet wood (40% dry weight basis) and large wood (6cm x 3cm c-s) tests showed efficiencies were improved to 20-22%. Accordingly the stove was improved for the standard conditions by decreasing the undergrate air flow and raising the baffle under the back pot. After these changes, PHU2 was increased to 20% for standard tests.
The alterations to the baffle and air duct changed the PHU without affecting the power output of the stove, presumably by slowing down the draught and releasing more heat to the pots. Observations through heat-resistant glass dishes confirmed that the flame pattern was improved.
A look at the graph of Power v PHU2 shows that the unoptimised stove tended to work less efficiently at high power. It also emphasised the flat response to power of PHU with this stove. This indicated a good stove for the user who may have to burn various fuels.
Although no cooking tests were carried out, the stove was very serviceable and easy to use during the water boiling tests. Most of the smoke was removed by the chimney. It burned Iroko (a dense wood and normally quite difficult) very well, wet wood quite reasonably, and gave very good average PHU2. Based on these findings it is a stove well worth consideration.
(Summary of a forthcoming Technical Paper)
Newsletter of the Intermediate Technology Development Group Stoves Project at the Applied Research Section, Shinfield Road, Reading, Berks, RG2 9BE, UK
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