CFD-Based Aerothermal Design Verification of Coffee Cabinet Dryer

Traditional sun drying remains the primary practice among smallholder coffee farmers in the Philippines, often leading to an inefficient and inconsistent drying process. While transitioning to mechanical drying improves product quality, achieving uniform airflow in cabinets with multiple trays often requires costly post-fabrication modifications, resource-intensive trials, and repetitive field testing to fine tune the performance of the system. To reduce inefficient and repetitive trial-and-error procedures, a pre-fabrication design verification of a small-scale mechanical cabinet dryer was conducted using COMSOL Multiphysics. This study explores how the dryer’s geometry influences its aerodynamic and thermal performance under baseline, no-load conditions prior to fabrication. The system was simulated to deliver an inlet air velocity of 1.56 m/s and a controlled heat flux to maintain 40oC. Results revealed steady pressure equalization within the plenum chamber, which successfully mitigated non-uniform airflow. As a result, a relatively high Velocity Uniformity Index of 0.84 was achieved across the tray layers. In addition, internal turbulent mixing contributed to a more stable thermal profile, reaching a near-ideal Temperature Uniformity Index of 0.99. These findings reveal that the core geometry of the dryer performs well from an aerodynamic standpoint. By achieving flow equalization in a no-load setting, the study provides an optimized baseline design, helping reduce the need for extensive trial-and-error during future prototyping and testing under actual operating conditions.