CFD Simulation via User-Defined Functions and Resizing of a Solar Dryer for Processing 25 kg of Pineapple

This article presents an optimization and numerical simulation (CFD) study of an indirect solar dryer designed for pineapple drying, aiming to reduce critical post-harvest losses in West Africa, particularly in Benin. Unlike many previous studies that are often limited to modeling an empty drying chamber, this work evaluates the system under real operational conditions by integrating an active load of 25 kg of pineapple. To achieve this, the authors utilize the ANSYS Fluent solver and develop three specific user-defined functions (UDF) to dynamically simulate coupled heat and mass transfers, thereby accurately representing the airflow resistance and active water evaporation within the product's porous matrix. Structurally, the system underwent several major geometric improvements, including resizing the solar collector to 5.54 m 2 to provide the 46.53 × 10 6 J required to extract 20.59 kg of water, and optimizing the spacing between trays to 250 mm. The results demonstrate that this new configuration effectively eliminates dead recirculation zones and ensures a homogeneous distribution of hot air. Quantitatively, the system maintains a highly uniform drying atmosphere, with temperature variations between the five trays limited to a narrow range of only 0.4°C (52.9°C to 53.3°C) and an inter-tray hygrometric gradient of less than 0.04%. While the model demonstrates high numerical robustness with a minimum orthogonal quality exceeding 0.1, the current lack of specific experimental validation for this resized configuration is acknowledged as a limitation, providing a foundation for future in situ correlation studies.