CONTRIBUTION TO THE IMPROVEMENT OF ENERGY AND TECHNICAL PERFORMANCE OF AN INDIRECT SOLAR DRYER FOR AGRI-FOOD PRODUCTS: STUDY, REALIZATION AND EXPERIMENTAL TESTS

According to the Food and Agriculture Organisation of the United Nations, during periods of high production abundance, the losses of agri-food products observed in West Africa amount to 25% for cereals and 50% for fruits and vegetables. Strengthening agri-food preservation techniques through solar drying is a major challenge for African countries with high solar energy resources. This study contributes to the improvement of the energy and technical performance of indirect solar dryers for packaging agri-food products on a small scale. The objective achieved is the design and realization of an indirect solar dryer with forced convection with chimney effect for a better evacuation of the moisture extracted from food products. With a solar collector of 136W of thermal power, the dryer made allows to remove 0.85kg of water from a unit of a kilogram of tomatoes at a temperature not exceeding 60°C for thirteen hours (13 hours) of time. In this way, the nutritional properties of the products are preserved and any microbial proliferation is inhibited. This work includes an experimental part which consists of studying the evolution of the thermo-physical parameters of the drying air (temperature and degree of humidity) in the drying box during characteristic days. The analysis of the data and its interdependencies makes it possible to select the types of agri-food products that can be effectively dried with this device. The study also shows that the air path in the dryer and its temperature are the most important parameters to be optimized for good drying kinetics.