Development of a low cost and energy efficient tobacco curing barn in Zimbabwe

摘要

Most of the tobacco in Zimbabwe are grown by small scale tobacco growers who rely on wood-fuelled inefficient conventional barns with fuel wood requirements as high as 14 kg wood to one kilogram of cured tobacco leaf. This level of fuel wood use is not sustainable as it results in massive tobacco-curing related deforestation. The main objective of this study was therefore to design an energy efficient barn (Kutsaga Counter-Current 1). Thereafter, the curing efficiency of the barn was evaluated against the energy efficient rocket barn and the standard conventional barn. Wood from Eucalyptus camaldulensis at 12% moisture content was used as the curing fuel and all the barns were loaded with tobacco of the same variety and fired at the same time. The results indicate that the barn utilizes 3.5 kg of wood to produce a kg of cured tobacco as compared to an average of 4.25 and 5.32 kg in the rocket and conventional barns, respectively. This high efficiency of the barn is derived from an effective heat exchange system. Given the high fuel use efficiency, the Kutsaga Counter-Current 1 barn is recommended for use by small scale tobacco growers.