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      箱式烘烤烟叶回潮过程数值模拟与均匀性分析

      Numerical Simulation and Uniformity Analysis of the Rewetting Process of Flue-cured Tobacco in Box-type Curing

      • 摘要: 为深入分析箱式烘烤烟叶回潮过程均匀性,本研究通过构建烟叶回潮过程湿分传递理论模型,比较瞬时平衡边界条件回潮模型(IE)与动态平衡边界条件回潮模型(DE)的预测准确性,基于箱式回潮环境监测,模拟烟叶回潮过程。结果表明,与IE模型相比,DE模型通过引入叶片τ=1 580、主脉τ=9 372的吸湿平衡特征参数,使叶片和主脉的最大模拟误差分别由14.1%、36.1%降至7.4%、7.1%,明显提升了预测精度;分析模拟回潮结果得,烟叶尺度上,叶片回潮速率远高于主脉;单个箱体尺度上,烟叶回潮过程的均匀性呈现出先降低后升高的趋势,水分由外层向内层逐渐渗透,箱体下部烟叶含水率要高于箱体上部;烤房尺度上,随着加湿机距离的增加,烟叶含水率逐渐降低,10个箱体均为中心区域的含水率最低,此外,1~3号箱体的回潮均匀性表现良好。综上,基于湿度场与物料特性构建叶片和主脉动态平衡边界条件回潮模型分析烟叶回潮均匀性,可为下一步烟叶回潮工艺优化提供依据。

         

        Abstract: To analyze the uniformity of flue-cured tobacco rewetting in a box-type barn, this study constructed a theoretical model of moisture transfer during the rewetting process. Through comparative analysis, the accuracy of rewetting simulations under instantaneous equilibrium rewetting model (IE) and dynamic equilibrium rewetting model (DE) boundary conditions was evaluated, with both simulations calibrated against environmental data from the box-type rewetting system. Results demonstrate that compared with the IE, the DE introduces the moisture absorption equilibrium characteristic parameters of the leaf with τ=1 580 and the main vein with τ=9 372, reducing the maximum simulation errors of the leaf and the main vein from 14.1% and 36.1% to 7.4% and 7.1% respectively, which significantly improves the prediction accuracy. At the scale of single leaf, the rewetting rate of leaf is much higher than that of the main vein. At the scale of a single box, the uniformity of the rewetting process of flue-cured tobacco first decreased and then increased. The moisture gradually penetrates from the outer layer to the inner layer, and the moisture content of the tobacco leaves at the lower part of the box is higher than that at the upper part. At the scale of barn, as the distance from the humidifier increases, the moisture level gradually decreases, with the central area of all ten boxes showing the lowest moisture levels. In addition, rewetting uniformity was optimal in boxes 1–3. In conclusion, the rewetting model with two-component (leaf and vein) dynamic equilibrium boundary conditions constructed based on the humidity field and material properties is used to analyze the rewetting uniformity of flue-cured tobacco, which provides a scientific foundation for optimizing future flue-cured tobacco rewetting processes in box-type barns.

         

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