Thermal energy conservation strategy: A case of a modified local charcoal stove utilisation

The proliferation and use of charcoal stoves is on the increase even in urban locations in Africa despite the environmental hazard associated with charcoal production. The rising cost of fossil fuel, the smokeless nature of charcoal combustion and probably inexistent or ineffective legislation against deforestation could be the reasons for this. This study aims at more efficient use of the energy available from the use of common charcoal stoves. A common slightly improved charcoal stove was placed in an enclosure with openings for air inflow and heating of the pot, and linked to a heat receiver through a duct all made of burnt brick. The stove enclosure, heat receiver inlet and outlet, and the ambient temperatures were measured during the boiling of water for 3 periods/stages of 22 minutes per day for 6 days. The quantity of heat generated in the enclosure, the percentage reaching the heat receiver and the total heat losses from the system were computed under steady state conditions. A mean value of 93.85 kJ/kg of heated air was generated in the enclosure with about 34.33% reaching the heat receiver. The mean temperature within the heat receiver was 70.4 °C and the mean total heat loss from the system was about 6.4 kJ/kg of air. There was a significant difference between the thermal energy lost and trapped within and amongst the three stages; (p ≤ 0.05) and significant also with time for the three stages and within the stages of operation (p ≤ 0.05) with positive correlation of total heat lost and the heat trapped for conservation. This significantly indicates great potentials for utilising part of the thermal energy generated from the use of charcoal stoves for cooking as losses for other alternative uses such as drying and other forms of preservation of foodstuff thereby improving their utilisation efficiency and probably compensating in part for the adverse effect on the environment as a result of sustained charcoal production. This is an eye-opener situation in the quest for total energy conservation and conversion in any energy system.