PERFORMANCE OF FREE-CONVECTIVE SOLAR DRIERS FOR COCOA IN ST. LUCIA

In this study, four different solar driers were tested under field con ditions in St. Lucia to demonstrate their ability to reduce the moistu re content of cocoa beans (Theobroma Cocoa L.) to a level not requirin g subsequent polishing. An indirectly heated solar drier (ISD) coupled with a flat-plate collector and a direct solar drier (DSD) were compa red with open air sun drying on perforated steel (OAS) and non-perfora ted wooden surfaces (OAW). The ability of each method to reduce cocoa beans to safe storage moisture levels (<8% wb) for loading capacities of 13.7 and 40.4 kg/m(2) were compared. Temperature rises were 15 and 20 degrees C above ambient in the ISD and DSD, respectively. The drier s were more efficient in removing moisture throughout the drying proce ss at the lower loading capacity of 13.7 kg/m(2) and particularly duri ng the initial stages of drying. Sun drying on a wooden surface proved more effective than other methods at 13.7 kg/m(2) loading in the fina l stages of drying. Although the ISD performed better at the higher lo ading capacity, its cost and the short season for cocoa harvest makes it prohibitive for all but the largest producers. The DSD, while less efficient in drying cocoa beans, costs only about twice as much as ope n air driers and it has the advantage of not requiring labor to cover the beans during rainfall.