Experimental characterization and simulation of solar drying process for Myrtus communis leaves optimization

• LESPAM isotherm accuracy validated via gravimetric tests. • Midilli model fit provided the most accurate drying kinetics. • CFD airflow insights showed drying fronts and non-uniform flow. • Design modifications proposed to enhance drying uniformity. This study experimentally characterizes Myrtus communis leaves and integrates those data into a computational model to improve indirect solar drying performance. Sorption isotherms were measured by the static gravimetric method at 28, 40, and 50°C; GAB and the medicinal-plant-tailored LESPAM models best described adsorption/desorption (maximum R 2 up to 0.9989 and reduced χ 2 as 6.3 × 10 -4 ). Thin-layer drying experiments in an indirect solar dryer (collector heat flux 700 W/m 2 ; inlet air 0.8 m/s) were fitted with several kinetic models: the Midilli model performed best (R 2 = 0.9944; reduced χ 2 = 1.79 × 10 -4 ). Experimentally, leaves reached marketable dryness in about 6 h under Constantine (Algeria) conditions. COMSOL Multiphysics CFD simulations, driven by measured sorption and kinetic parameters, reproduced intra-chamber maxima of 319 K and air speeds up to 0.83 m/s, and captured humidity evolution showing negligible vapor flux after 6 h. Non-uniform airflow is identified as the main cause of drying heterogeneity, and design/operational changes (e.g., adjusted inlet velocity and tray layout) are recommended to improve uniformity. As result, ensuring uniform airflow distribution helps in minimizing the experimental effort and reduce parameter dependency, hence simplify the overall process for the benefit of general use in industrial applications. The combined experimental-computational approach enables realistic performance prediction. Proposed design modifications has been studied, which leads to optimize the airflow distribution, and as result, reducing the heterogeneity inside the solar dryers has been achieved.