Influence of the Aerothermal Parameters of an Indirect Solar Dryer on the Intermittency of Bioproduct Drying: The Case of Fruits and Tubers

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Résumé

This study examines the impact of the aerothermal factors of an indirect solar dryer on the intermittent and continuous drying dynamics of four crops: mango, banana, potato, and sweet potato. The experiment was conducted under sustained global solar radiation reaching 1000 W?m?2, with drying temperatures ranging from 55?C and controlled forced convection airflow to stabilize the airstreams. The study of thermal profiles and drying kinetics shows that intermittent processing controls mass transfer by promoting internal water redistribution during pause phases, preventing hardening and maintaining a steady evaporation process. The dynamics of moisture migration are quantified by contrasting effective diffusion coefficients Deff: 2.67 × 10?9 m2?s?1 for mango, 9.08 × 10?10 m2?s?1 for banana, 8.39 × 10?10 m2?s?1 for potatoes, and 7.63 × 10?10 m2?s?1 for sweet potatoes. These figures, which are higher for mangoes due to their more porous structure, are consistent with the standards established in the literature for horticultural and starchy products. During theoretical validation, the Page and Logarithmic models show excellent agreement with the experimental data. Page model proved to be optimal for mangoes (R2 = 0.9968), while the logarithmic model better described the drying of bananas (R2 = 0.9979), as well as that of potatoes and sweet potatoes (R2 = 0.9988). These results show that controlling the aerothermal parameters and implementing an intermittent drying regimen improve drying efficiency while ensuring a rigorous mathematical prediction of the process.

Mots-clés

Intermittent Drying, Continuous Drying, Effective Diffusivity, Drying Kinetics, Aerothermal Parameters,