Accueil > Science et Technologie > Revue des Energies Renouvelables > volume 12 > Numéro 03

Evaluation of drying parameters and sorption isotherms of mint leaves (M. pulegium)

Ethmane Kane C.S., Kouhila M., Sid Ahmed M.A.O.

This paper deals with sorption isotherms and drying kinetics of mint leaves
(M. pulegium). The sorption isotherms have been determined using a static gravimetric
method and then fitted by GAB, equation at 30, 40 and 50 °C over a range of relative
humidity from 0.05 to 0.9. Experimental data for the drying of mint was obtained at four
temperatures and two flow rate. The increase in air temperature significantly reduced the
drying time of the mint leaves. Drying data of this material were analysed to obtain
diffusivity values from the falling rate-drying period. In this period, moisture transfer
from mint leaves was described by applying the Fick’s diffusion model. Effective
diffusivity varied from 1.9871 × 10-11 to 1.4221 × 10-10 m2/s and increased with the air
temperature. An Arrhenius relation with an activation energy value of 57.12 kJ/mol
expressed effect of temperature on the diffusivity. The expression of the drying rate is
determined empirically from the characteristic curve of drying. The logarithmic model
was found to satisfactorily describe the kinetics of air-drying of mint leaves.