Thermophysical characterization and mathematical modeling of convective solar drying of raw olive pomace

• Mathematical modeling of convective solar drying of raw olive pomace.
• Drying facilitates the transportation and the utilization of raw olive pomace.
• Utilization of solar drying of agricultural residuals.
• Solar dryers contribute to promote solar energy use.

This experimental study is focused on the convective solar drying of raw olive pomace. In this investigation, the desorption/adsorption equilibrium water content of this product has been determined at the drying temperatures of 30 °C, 40 °C and 50 °C, by using the gravimetric static method. Moreover, four mathematical models have been used to predict the hygroscopic behavior of the product during drying process. From a thermodynamic point of view, more significant changes are felt in the thermodynamic properties of natural raw olive pomace in terms of differential enthalpy and entropy of sorption. The characteristic drying curve (CDC) of raw olive pomace has also been experimentally determined. This kinetic measurement is carried out for three temperature values of drying air (45 ± 0.1 °C, 60 ± 0.1 °C and 80 ± 0.1 °C) and also for two values of drying air flow rate DvDv (0.042 ± 0.002 m3 s−1 and 0.083 ± 0.002 m3 s−1). The drying rate is empirically determined from the characteristic drying curve, and four mathematical models have been used to describe drying curves. The Midilli–Kucuk model seems to be the appropriate model for drying of the product studied here.