REALIZATION OF A SOLAR DRYER INDIRECT FOR THE KINETIC STUDY AND THERMODYNAMIC PROPERTIES OF MORINGA OLEIFERA LEAVES.

In this article, we first presented the steps followed in the conception and realization of an indirect solar dryer in the Applied Energy and Mechanics laboratory (LEMA) of the Polytechnic School of Abomey Calavi. After wards,we studied the thermal performance of the device and the influence of various drying conditions (temperature, relative humidity and air flow) on the drying process and the effective diffusivity of Moringa oleifera (Lam) leaves.The results show that the dryer recorded moderate temperature values varying between 38°C and 55°C over the entire test period. The relative humidity of the drying air present an evolution inversely proportional to that of the ambient air. The drying curves obtained currently, only a single periodat decreasing speed (phase 2). In this period, the transfer of humidity between the air and the product was evaluated by applying the diffusive Fick model. The effective diffusivity varied from 8.456 10 11 to 8.9567 10 8 m2s 1with an increase in drying temperature and hot air flow rate. The Arrhenius relation ship expressing the effect of temperature on the effective diffusion coefficient gives an averageactivation energy value of 86.462 KJ/mol ±1.98. The drying speed is determined empirically from the Drying Characteristic Curve (CCS). Among the five models developed, Midilli et al. (2002) adequately describes the drying kinetics of Moringa oleifera leaves under the experimental conditions imposed.