Conjugate heat and mass transfer modelling for food drying process optimization

Abstract Convective drying is a widely used food preservation technique, where hot, dry air removes moisture from a food sample. This process is both energy- and time-intensive, necessitating careful design, modelling and optimization. However, traditional models often overlook critical factors such as flow turbulence and food–air interfacial processes. This research investigated the influence of practical operating conditions on drying performance and energy consumption. A computational fluid dynamics (CFD) model was developed and implemented in the OpenFOAM package. The model simulated heat and mass transfer within the food sample and surrounding air, including interactions across the food–air interface. A semi-cylindrical carrot sample with a 10 mm diameter and 60 mm length was used as the food material. Four air inlet parameters were varied: temperature (40–80 °C), relative humidity (10–30 %), speed (0.5–5 m/s), and turbulence intensity (0–20 %). The results highlighted the predominant role of inlet air temperature in process control, energy efficiency, and product homogeneity. Increasing the inlet air temperature from 40 to 80 °C reduced the drying time by 50 % and energy consumption by 30 %. In contrast, air relative humidity showed almost no effect within the studied range. Increasing air velocity reduced drying time at the expense of higher energy consumption. This research advances the numerically guided design of convective drying for food materials.