Seed Drying: Hydraulic Mechanism

Seed Drying Via Hydraulic Mechanism, ANSYS Fluent

Description

This project simulates seed drying through a hydraulic mechanism process using ANSYS Fluent. Drying refers to the removal of moisture from grain, a process critical for reducing seed moisture content to a safe level that preserves viability and stability during storage — without adequate drying, seeds risk rapid spoilage from mold growth, self-heating, and increased microbial activity.

The geometry consists of a simple semi-cylindrical chamber, with a set of spherical shapes positioned inside representing wet seeds. Hot airflow enters from the bottom of the chamber at 303.15 K and 0.15 m/s, moving upward and exiting through the top. As this hot air stream moves through the chamber, it carries moisture away from the seeds — importantly, this occurs through moisture transmission from the seed region to the surroundings, not evaporation, which is what distinguishes this as a hydraulic drying mechanism rather than an evaporative one. For comparison, evaporation-based drying (using the Discrete Phase Model to track individual grain particles) is covered separately in the related "Grain Drying Device" and "Rice Dryer" projects.

The 3D geometry was designed in Design Modeler, representing the semi-cylindrical chamber interior with the spherical seed particles positioned at its center. The domain was meshed in ANSYS Meshing using an unstructured grid totaling 6,286,496 elements.

Methodology

Since the computational domain contains a combination of air and H₂O, the Species Transport model was used to capture this mixture's behavior. The spherical seeds themselves were modeled as porous media, with moisture assumed to have penetrated the internal cavities of each seed, defined with a porosity coefficient of 0.418. The seed zone was initialized as wet, carrying the initial moisture content that the simulation tracks as it dries.

Conclusion

Results include 2D and 3D contours of temperature, pressure, and velocity throughout the chamber. The results show that moisture (H₂O) content within the seeds progressively decreases as the hot air stream moves upward through the chamber — confirming that the hydraulic drying mechanism successfully transports moisture away from the porous seed particles and out of the domain via the rising airflow.