Fixed‐bed drying of grains is a widely used method for determining temperature and humidity changes and pressure drop characteristics during aeration. In this study, an accurate particle‐resolved computational fluid dynamics (CFD) numerical model was developed to investigate the flow and heat transfer in fixed beds of soybean, wheat, and maize grains. A randomly filled non‐spherical grain fixed bed structure was generated using the discrete element method (DEM), and the contact areas between the packed particles are automated. The distribution of grain particles near the wall surface was approximately circular, and the circle became more regular with increase grain sphericity. Compared with the fixed beds of soybean and maize, there was no significant stratification in the fixed beds of wheat, and the difference between the peaks and troughs of porosity oscillations was smaller. Detailed particle‐resolved CFD simulations of the flow and heat transfer in fixed beds with different grains were performed. The results showed that the pressure drop results of the DEM–CFD simulation of different grain shapes were in good agreement with the Nemec–Levec equation and experimental results. The velocity and temperature distribution in the fixed bed have obvious non‐uniform distribution characteristics, which are more visible in the maize pile. Regions with high porosity have a higher average velocity, and the temperature near the wall is higher than that at the center when the heat transfer is unbalanced. The DEM‐CFD model includes the heat conduction process between the fluid and solid phases, which is consistent with the experimental temperature results. Practical Applications In this work, an accurate particle‐resolved computational fluid dynamics numerical model was developed to investigate the flow and heat transfer in fixed beds of soybean, wheat, and maize grains. The randomly filled non‐spherical grain fixed bed structure is generated by the discrete element method (DEM), and the contact areas between the packed particles are automated treated. The pressure drop and heat transfer processes of different grains were measured using the fixed bed drying experimental platform. The results show that the pressure drop results of DEM–CFD simulation of different grain shapes are in good agreement with Nemec–Levec equation results and experimental results. The DEM‐CFD model includes the heat conduction process between fluid and solid phases, which is in close agreement with the experimental temperature results.

To investigate the influence of pore structure distribution on the flow and heat transfer during the aeration process of a grain pile, an anisotropic continuous model (ACM) was developed based on the homogeneous continuous model (HCM). The improved ACM includes spatial resistance factors and effective thermal conductivity correction coefficients. The experimental results were compared with the particle‐resolved computational fluid dynamics (PRCFD) and ACM simulation results to verify the accuracy. At higher inlet velocities, the HCM underestimated the pressure drop in the wheat fixed bed, with an average deviation of 21%. In contrast, the improved ACM incorporates the effect of resistance factors and had an average deviation of less than 10% from the experimental. By simulating the pilot‐scale bin aeration system, the accuracy of the improved ACM applied to the real bin was ensured, considering the change in the porosity of the grain pile along the center of the bin to the bin wall and the grain pile height direction. The range of variable porosity distribution was set at .35–.45, and the total average deviation between the ACM simulation static pressure and the experimental value was 9.7% when the inlet airflow velocity was .019 m/s. The simulated temperature of the ACM matches the measured temperature better compared to the temperature values of the grain pile at different heights in the HCM with a constant porosity of .45. Therefore, the impact of four central air collection duct forms on airflow and temperature was discussed, and it was determined that the pipe with a larger diameter at the top and a smaller diameter at the bottom air collection duct was more advantageous when used in a horizontal aeration system by applying the improved ACM to different scenarios.Practical ApplicationsThis study introduces the resistance factor and effective thermal conductivity in a laboratory‐scale fixed bed of wheat. An improved anisotropic continuous model was established for simulating the flow and heat transfer in the fixed bed during the aeration process. The improved anisotropic continuous model accurately reflected the non‐uniformity of fixed bed flow and temperature transfer in the fixed bed. This model can be employed for simulating flow and heat transfer in large‐scale actual storage systems characterized by heterogeneous pore distribution, while ensuring appropriate computational efficiency and precision.

To investigate the pore structure distribution and the coupled heat and moisture transfer during the drying process of the grains, this study focuses on fixed-bed corn drying with varying levels of broken kernel rate. A model of internal flow and conjugate heat and mass transfer was established for the drying process. Random packing models of whole and half corn kernels with different proportions were generated using rigid body dynamics (RBD), and the porosity, airflow distribution, and coupling of temperature and moisture transfer in fixed beds with different levels of broken kernel rate were analyzed. A fixed-bed corn drying device was developed, and the effects of broken particle contents of 0%, 10%, 20%, and 30% on drying characteristics were studied. The research findings reveal that the radial porosity in the fixed bed exhibits an oscillating distribution, with the localized porosity decreasing as the broken kernel rate increases. Increasing the broken kernel rate intensifies the curvature of the airflow paths within the fixed bed, increasing the pressure drop in the bed. The broken kernels fill the gaps between the whole kernels, improving the uniformity of the velocity distribution within the fixed bed. Under various packing models, the average discrepancy between pressure drop obtained from Particle-resolved Computational Fluid Dynamics (PRCFD) simulations with experimental remains below 15%. The increase in broken kernel rate within the fixed bed enlarges the heat transfer area, resulting in an elevation of the transient heat transfer characteristic parameters during drying. Simultaneously, the broken kernel rate increases the surface area of mass transfer, thereby enhancing the moisture transfer rate within the fixed bed. Compared to the fixed bed without broken kernels (0%), which requires 560 min to dry the corn pile to a safe moisture of 14% (d.b.), the drying time is reduced by 60 min, 100 min, and 130 min for the respective broken kernel contents of 10%, 20%, and 30%, respectively. The PRCFD method successfully simulates the processes of convective heat and mass transfer in the fluid phase and thermal and mass diffusion in the solid phase, exhibiting a strong correlation with experimental data.