Passive Autarkic Solar Drying Techniques

Abstract

In many rural locations in Nigeria, grid-connected electricity is either unavailable, unreliable or too expensive. Thus in such areas crop drying systems that employ motorised fans or electrical heating are inappropriate. The large initial and running costs of fossil fuel powered dryers present such financial barriers that they are rarely adopted by small-scale farmers. In such conditions, natural circulation solar energy crop dryers appear to be increasingly attractive as commercial propositions. The advantage of the solar-energy tropical-crop dryer is that it requires a smaller area of land in order to dry similar amounts of crop that would have traditionally been dried in the open. Another advantage is that it will yield a relatively high quality of dry crop, because insects and rodents are unlikely to infest it during the drying process. The drying period is shortened compared with open air drying and protection is afforded from sudden downpours of rain. Thus the relatively low capital and running costs of these crop dryers and the improved crop quality achieved after drying, enable these systems to compete economically with traditional open-sun drying.