Enhancing supply chain efficiency for air transport of horticultural products by simplified heat and mass transfer modelling

Abstract

Maintaining temperature and quality stability of fresh horticultural products during air transportation is challenging due to highly variable thermal environments and limited airflow inside Unit Load Device (ULD) containers. This study developed a simplified three-dimensional heat and mass transfer model to predict product temperature and moisture evolution within a ULD container under realistic operating conditions. Plaster mangoes were used to avoid the variability of the real product properties. Convective heat transfer and three-directional thermal resistances were integrated into an unsteady heat balance model while the model parameters were calibrated using Monte Carlo simulation. A complementary mass transfer model, considering the ULD container as a closed moisture domain, was implemented to estimate product mass loss. Model performance was evaluated using cooling experiments under controlled conditions and field measurements in a ULD shipment from Bangkok to Paris by air transport. Simulated air and product temperatures showed good agreement with experimental data, with RMSE values below 3.5 °C. The model successfully captured the pronounced thermal load on top-layer boxes during tarmac exposure and the faster cooling of bottom boxes through conduction with the bottom wall during flight. Predicted mass loss (1.0-1.1%) also aligned with field data (1.1-1.2%). The model provides a practical tool for assessing the effects of operational and environmental conditions on fruit quality during air transport.