Upgrading the flatbed dryer with a solar-powered system for Tanzanian smallholders

About the project

UK-registered Partner: Natural Resources Institute, University of Greenwich – Dr Marcelo Precoppe
Africa-registered Partner: Intermech Engineering Limited – Emmastella Gakuo

Flatbed dryers consist of a simple container with a perforated screen in the middle, as a false floor, where the solid to be dried is placed. The heated air is forced into a plenum chamber below this perforated screen, passing through the orifices and then through the solid. Heat is generated by a burner, fuelled by kerosene, diesel, or gas. The burner is attached to a heat exchanger, and a fan, powered by an electric motor or a combustion engine, induces the forced airflow.

Flatbed dryers are popular in sub-Saharan Africa because they have low capital costs, are easy to operate, and can be used with several crops. However, flatbed dryers have two major drawbacks: low energy efficiency and non- uniform drying.

As part of this project, a stirrer for a flatbed dryer was developed to improve the dryer energy efficiency and the uniformity of the dried product. In addition, the project developed a solar collector to pre-heat the drying air, reducing further the amount of fuel needed during the drying operation.