Analytical solution of coupled heat and mass transfer equations during convective drying of biomass: experimental validation

Abstract

In this work, analytical solutions of the thin-layer and the Luikov models were proposed. For the thin-layer model, the moisture content and temperature distribution inside a biomass, assimilated to a parallelepiped material, are uniform whereas the Luikov model considers the sample as a porous medium. Analytical solutions of the Luikov model equations were obtained using Hermite’s zero-order approximation. These analytical solutions and those of the thin-layer model equations were applied to forced convection drying of two types of biomass: raw olive pomace (ROP) and deoiled olive pomace (DOP). It has been shown that the Luikov model is in good agreement with the experimental results except for the case where the sample has a thickness of 0.5 cm. In addition, thermal properties of ROP and DOP have been determined experimentally. On the other hand, a brief parametric study has been conducted and simultaneous effects of the dimensionless numbers: Luikov (Lu < <1), Kossovitch (Ko) and Posnov (Pn), on the drying process are highlighted. Thus, the increase of Luikov number accelerates the drying process and for specific couples (Lu and Ko) or (Lu and Pn), a remarkable change of dimensionless average water content with respect to dimensionless average temperature is observed, at the beginning of the drying process.