Effect of wood moisture content and log diameter on conversion efficiency of a drum Kiln

Abstract

Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.

In Zambia wood fuel, as a forest resource currently accounts for 80% of the country’s total energy consumption at household level. About 60.9% of households use firewood for cooking and 24.3% use charcoal while only 13.8% use electricity. Further in rural areas, 87.7% use wood for cooking, 9.5% use charcoal and only 1.5% used electricity. Traditional earth charcoal kilns are the dominant method used in charcoal production, they incur minimal construction costs for rural communities, but have low conversion efficiencies, ranging from 6 to 12%.This causes high annual rate of deforestation due to wood harvesting. For every ton of charcoal produced using traditional kiln depletes 0.1 hectares of woodlands. Zambia has 300 000 hectares per annum rate of deforestation that is increasing at rate of 4% per annum. This research was about determining the effect of moisture content and log diameter on the conversion efficiency of drum type charcoal making kilns by comparative studies in the field. The drum kiln is intended for use at the household level in periurban and rural areas. The log diameters used in the experimentation ranged from 0.04 m to 0.16 m on an average scale. The moisture content of the wood was determined by oven dry method (ASTM-D-4442) which yielded moisture content ranges of 26.92 wt. %, 9.42 wt. %, 8.63 wt. % and 9.06 wt. % respectively.