基于DEM-CFD的烟片堆积模型及其热风干燥特性研究OA

To improve the accuracy of drying simulation for piled materials during the re-drying process of tobacco strips,addressing the limitations of traditional continuum models that neglect the real stacking structure and dynamic gas-solid interactions,a coupled discrete element method-computational fluid dynamics(DEM-CFD)approach was adopted.A discrete packing model of tobacco strips was established,and its reliability was verified through experiments.The effects of inlet air temperature(60～80℃),relative air humidity(20%～40%),and inlet air velocity(0.50～0.80 m/s)on the moisture content and temperature of tobacco strips were systematically investigated.The underlying mechanisms were elucidated from the perspectives of convective and evaporative heat transfer.The results showed that at an inlet air temperature of 70℃,drying efficiency and temperature uniformity were well-balanced.Increasing the temperature to 80℃ tended to cause overheating and uneven drying at the bottom of the tobacco strip pile,while reducing it to 60℃ significantly slowed the drying process.Higher relative air humidity facilitated overall heating during the preheating and constant-rate stages but inhibited evaporative heat transfer,reducing the drying rate.When relative air humidity was increased from 20%to 40%,the average temperature during the constant-rate drying stage rose by approximately 6℃,while the evaporative heat transfer power decreased by about 0.017 W.Increasing the inlet air velocity significantly altered the stacking structure of the tobacco strips.When the inlet air velocity was increased from 0.50 m/s to 0.80 m/s,the stable void fraction increased 0.15,and the convective and evaporative heat transfer powers during the constant-rate drying stage increased by about 0.023 W and 0.022 W,respectively,resulting in a significantly improved drying rate.However,the enhancement effect diminished with further increases in air velocity.This research provides a theoretical basis for optimizing the process parameters in tobacco strip re-drying.