Design and construction of a cocoa bean solar dryer for smallholder farmers.

Abstract

Cocoa beans are the seeds from fruit pods of a tropical tree botanically known as Theobroma cacao L. (Family Sterculiaceae). Each pod contains at least 30—40 "cocoa beans" embedded in a mass of mucilaginous pulp within the pod. It is a perennial crop that responds well in rainy tropical areas, with a maximum annual average of 30-320C. The crop supports about 10,000 households. Organic cocoa is grown mostly in Bundibugyo, Mukono, Jinja, Kamuli, Buikwe, Masmdi, Mayuge, Iganga and Kayunga districts on a small scale. The challenge is that Ugandan cocoa farmers realize over 30% loss of harvested cocoa. The main cause is that cocoa is mainly harvested during rainy season where so many mature cocoa pods are realized. The main aim of the study is to design, construct and evaluate the performance of a locally constructed cocoa bean solar dryer for smallholder farmers. Specifically, it will be designed, fabricated and assembled in model-form to determine its suitability for the target users. The purpose of this project will address the problem of smallholder farmers drying of cocoa beans during bad weather period, by ensuring timely and precision drying of the crop using efficient and sustainable solar drying technology affordable by small scale farmers and processors. The technology shall target cocoa farmers in Jinja district where large volumes of cocoa are produced but most of them employ the traditional method of drying. This machine will also facilitate effective drying of the crop which will result in good quality of the final product with no discoloration and loss of nutritional value. A solar dryer with thermal energy storage is suitable for drying of cocoa beans. The prototype will be constructed using readily available local materials. The drying mechanism will be based on a combination of convective heating and direct radiation, with a provision for controlling the rate of airflow through the beans. Quality assessment of the dried beans will be shown at the end of the construction, the work, thus will provide a viable system for producing cocoa beans of good quality attributes, comparable with using the traditional sun-drying, but without the associated drudgery. All the data generated will be analyzed and economically evaluated.