| Boiling Point No. 13 - August 1987 |
By W.F. Sulilatu, TNO, May 87, 27 pp
This report describes the measurements to determine the performance of the Multi Pot Stove. The stove is designed for the typical West African cooking pots and is suitable to contain various pot sizes. After attention is given to the operating principle the efficiency, power range and combustion performance of the stove are treated.
A number of experiments have been carried out in order to investigate the influence of the combustion chamber height on combustion quality. The Index of Toxicity as a function of the power output is determined. The combustion quality of the Multi Pot Stove is acceptable for a woodburning stove.
The report compares the performance of the stove ( I -pot, portable, chimneyless, woodburning, metal/ceramic/vermiculite) with 3 recently developed West African stoves, Mai Sauki, Malagashe and Foyer Ameliore Metallique Multi Marmite (Niger). On the basis of the tests used, it is considerably more fuel efficient than the first two and slightly better than Multi Marmite.
The report is particularly interesting as it reports tests on the fumes produced to give an Index of Toxicity. This is the co/co2 ratio in the air collected in a cowl over the stove. The measurement and analysis of fumes from a chimneyless stove is obviously very difficult and may not give realistic results for Third World chimneyless stoves. The indices quoted range from 2-3 up to 5-12 compared with the Dutch national maximum prescribed of 1. The report therefore says that the stoves are not recommended for use in badly ventilated kitchens.
Figures are not quoted for other potentially dangerous gases or for particulates, some of which may be carcogenic. Tests need to be made with other fuels such as dung, residues, briquettes and charcoal for performance as well as emissions if the stove is to be widely promoted.
The multipot stove is portable and so would normally be used out of doors and so fuel efficiency should be measured in such conditions of wind rather than still air. Portability means that the stove could be taken into a badly ventilated kitchen on a wet day and cause unexpectedly high concentrations of fumes. These dangers are, of course, present with any chimneyless stove used indoors.
If the health risks from fumes are as serious and widespread as indicated in some of the articles in this journal, perhaps bodies such as TNO which have good laboratory facilities should seek to develop more accurate and comprehensive ways of testing Third World stoves and should initiate field tests to validate their lab. results.