A computational study on airflow balancing in a horticultural drying chamber

Simulations were conducted to study the airflow across skids of grapes in a horticultural grape drying chamber for the purpose of balancing the airflow to produce a uniform drying environment. The focus of the study was on the approach taken to provide balanced airflow using a computational fluid dynamics (CFD) tool combined with experimental data. The process was to first characterize the crate stacks by comparison of airflow simulations across a single crate stack to experimental data to establish resistance coefficients. The next step was to use these coefficients to simulate a row of stacked skids to establish corrections in terms of additional (variable) resistance that would result in balanced airflow. The corrected model was then used to simulate flow through the entire horticultural chamber to confirm that under the conditions of fan operation, the balance of airflow persists. The study shows that while the unmodified stacks had nearly 20% imbalance from the first to the last stack, the stack with resistance modifiers corrected this imbalance to within 5%, which is considered suitable for operation of the chamber.