Drying agricultural products by radiation and convection

Experiments on drying with radiation and convection under sun exposed and ventilated shelters were carried out at the laboratory. These experiments were done inside a blower, with lamps simulating the solar radiation. Some measurements on the kinetics of drying were taken. Under the effects of radiation, the temperature of the product becomes higher than that of the air of convection. The evaporation of water is essentially a thermal vaporization. The temperature of the air contributes indirectly to drying by increasing the evaporating capacity of the air. However, the air velocity factor has little effect on the variation of the water content. The water content at equilibrium on a dry basis is experimentally determined under the above-cited drying conditions. A relationship between the water content at equilibrium and the different drying parameters is determined. A phenomenological model for drying of agricultural products is elaborated, using climatic parameters such as the air velocity, moisture under shelter, the radiation to which the product is exposed, the overall conductance of mass transfer and a coefficient due to the radiation