Abstract
In the present case study, a moisture diffusion model is developed to simulate the drying kinetics of Lavandula x allardii leaves for non-stationary convective drying regimes. Increasing temperature profiles are applied over the drying duration and the influence of temperature advancing rates on the moisture removal and the drying rate is investigated. The model assumes a one-dimensional moisture transfer under transient conditions, which occurs from the leaf center to the surface by liquid diffusion due to the concentration gradient developed by the surface water evaporation caused by the difference of water vapor partial pressure between the drying medium and the leaf surface. A numerical solution of Fick’s 2nd law is obtained by an in-house code using the finite volume method, including shrinkage and a variable temperature-dependent effective moisture diffusion coefficient. The numerical results have been validated against experimental data for selected cases using statistical indices and the predicted dehydration curves presented a good agreement for the higher temperature advancing rates. The examined modeling approach was found stable and can output, in a computationally efficient way, the temporal changes of moisture and drying rate. Thus, the present model could be used for engineering applications involving the design, optimization and development of drying equipment and drying schedules for the examined type of non-stationary drying patterns.
Highlights
Lavender is an important aromatic plant for essential oil production used by a series of industries for different applications
The model is validated against experimental measurements and the drying kinetic curves along with the drying rates are evaluated below
Higher drying temperatures levels are applied in a shorter period of time for the greater temperature increasing rates; a reduced overall drying time is associated with higher temperature advancing rates
Summary
Lavender is an important aromatic plant for essential oil production used by a series of industries for different applications. Convective drying is a drying method applied widely on most agricultural products due to the cost-effectiveness and the scalability to different applications. Non-stationary drying schemes involving drying parameter alterations over time or different kinds of intermittency may lead to improved output in terms of product quality and energy saving [1]. Such drying regimes are reported for medical and aromatic plants of peppermint (Mentha piperita L.)
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