Simulation study of moisture and heat migration during hot air drying of corn with stacked structures based on CFD-DEM

Granular agricultural products generally exhibit hygroscopicity and irregularity, and the moisture and heat migration involved in their industrial drying process are complicated. In this study, corn, a representative crop of horseshoe-shaped agricultural products, was evaluated and the best conditions for the hot-air drying of corn were obtained via response surface optimization: the drying temperature of 45 °C, the air velocity of 0.8 m/s, and the initial wet basis of 24 %. SolidWorks, Digimat, Abaqus, Hyper Mesh, Space Claim and other software were used to construct a physical model of corn pile, and depending on the corn kernels in the grain heap as the particle solid phase and the inter-kernel voids as the fluid gas phase, the RNG K-ε turbulence model was introduced, combined with the heat-mass non-equilibrium principle, a mathematical model of heat and mass transfer in corn grain pile was constructed. The simulation boundary conditions were set in combination with the optimal drying conditions of corn, and the wet heat transfer model was solved by COMSOL software. The results of this study demonstrate that the simulated values of moisture and temperature of corn grain pile during the drying process are consistent with the experimental values, with the maximum error for moisture as 5.4 % and the maximum error for temperature as 6.8 %, indicating the three-dimensional model is able to simulate the hot-air drying process of the corn grain pile very well.