Sensitivity Analysis of a CFD Modelling System for Airflow and Heat Transfer of Fresh Food Packaging: Inlet Air Flow Velocity and Inside-Package Configurations

Abstract

Cooling of fresh produce inside ventilated packaging is one of the important postharvest operations to maintain the coolchain of horticultural produce. In two recent articles, we described the development of CFD-based mathematical models for thermodynamic design of ventilated packaging systems and presented the results obtained from model testing based on fresh apples undergoing rapid cooling inside layered cartons, pallets of cartons, and bulk bins. In the current article, we present the results of a sensitivity analysis of the modeling system under refrigerated air cooling of apples inside a carton used in the horticultural industry. Sensitivity tests showed that inaccurate input value of the inlet air velocity within 10% would contribute to inaccuracy of about 0.5 ºK in the model predictions, which is within the measurement error of most temperature measuring devices used in the postharvest industry. Variations in vent areas on both front and back walls of the package within ±20% did not significantly alter the model predictions in the near-inlet region, but had noticeable effects at the package centre and near-outlet regions. Altering the position of vents did alter the heat transfer between air and packaged produce, presumably by changing the airflow distribution among the layers of produce inside the package. Sensitivity of the model to changes in the gap between the trays and package walls highlights the importance of gentle handling of packages to minimize lateral movement of trays and fruit prior to stacking for precooling and long-term cold storage.