A natural convection solar fish dryer consisting of a flat-plate solar collector, drying chamber, and an auxiliary heater was designed, constructed and tested in the Philippines. The dryer is capable of drying 5 kg of fish in 10 hours. / Water was first heated in a flat-plate solar collector then through thermosyphon effect, heat and mass was moved to the heat exchanger where heat was transferred to the air. Heated air was allowed to flow through the drying chamber where trays of prepared samples of fish were laid. Pre-drying treatment of fish similar to those used in commercial practice, were used for individual drying experiments in order to permit a general evaluation of the system. / Seven drying experiments using different fish samples were conducted and the data generated was used to determine the efficiency of the system in terms of solar energy utilization. Results indicate that the system function efficiently at a minimal water temperature increase of 10$ sp circ$C, and the dryer operates at a system efficiency of 9 per cent which compares well with the findings of Yu Wai Man (1986) which found that natural convection solar dryers operate in the efficiency range between 7 to 14 per cent.

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An indirectly heated solar drier fitted with a flat plate collector and a directly heated solar drier were compared with open air sun drying of cocoa beans under field conditions in St. Lucia. Sun drying was conducted on two surfaces, perforated steel and non perforated wood. The methods were examined for the ability to adequately dry fermented beans and effect on quality. Loading rates of 13.5, 26.9 and 40.4 kg/m$ sp2$ were examined. / Temperature increases of 15$ sp circ$C and 20$ sp circ$C above ambient were achieved in the indirect and direct drier, respectively. The solar driers were more efficient than sun drying units at removing moisture throughout at loading rates of 26.9 and 40.4 kg/m$ sp2$ but only in the initial stages at 13.5 kg. External mould development was therefore reduced. Open air sun drying on the wooden surface proved more effective in the final stages at 13.5 kg/m$ sp2$. / The dried beans were of similar internal quality despite faster drying in the driers. The various drying methods and loading rates produced beans of similar pH while only loading rates affected titratable acidity differently. The direct solar drier achieved lower final moisture levels at high loads and was the cheaper alternative.

The Republic of Guinea is located on the west coast of Africa at about 11° North latitude. A large portion of Guinea's supply of protein is dried fish. The actual drying method operates under open air, the foodstuff being unprotected from unexpected rains, windborne dirt and dust, and from infestation by insects, rodents, and other animals. More, the deforestation rate is increasing year after year, depleting the source of fuel for drying. Practical ways of drying fish cheaply and sanitarily would be welcome.The present work develops a prototype solar dryer on the basis of natural convection of air. The device is comprised of a glazed flat plate collector, a furnace with translucent walls, and an air tunnel adjoining the two. Air entering the collector is heated and flows into the furnace where energy is absorbed by pieces of fish placed on horizontal racks. The air exits through an opening in the top of the device carrying moisture with it.Using the prototype solar dryer, a fish drying experiment was conducted at the Center for Energy Research, Education, and Service (CERES) at Ball State University. The primary objectives were to investigate drying rates, times, and loads expected for a dryer constructed using simple techniques and materials readily available in the Republic of Guinea. The drying experimental results are in many ways similar to those reported by previous authors.The solar dried product appears to be superior to the product of current drying methods and the foodstuff is protected from infestation or contamination during drying.Future work suggested by the project experience includes refinement of the dryer design and additional fish drying experimentation. An economic analysis would also yield information on the feasibility of widespread use of solar dryers for drying of fish in the Republic of Guinea. / Department of Physics and Astronomy

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