滚筒内烟丝干燥过程的数值模拟

为了解析滚筒干燥条件对烟丝干燥过程中筒内的温湿度场和流场的影响规律，采用数值模拟开展烟丝滚筒干燥的筒内温湿度场的研究。通过干燥实验测量滚筒内部空气湿度来验证模拟结果的准确性，探究进口热风温度、进口热风速度、筒壁温度和滚筒转速等因素对滚筒干燥过程中内部水分分布的影响规律。结果表明:①增加进口热风温度会使蒸发过程加快；②提高进口热风速度能加强滚筒前段部分的水分蒸发，但进口热风速度过大会造成滚筒内整体水分浓度下降；③改变筒壁温度直接影响烟丝温度与筒内的平衡含水量，筒内平衡含水量随着筒壁温度的升高而增加；④增加滚筒转速会减少烟丝在筒内的停留时间，不利于烟丝的干燥。 

Numerical simulation of drying process of cut tobacco in a cylinder dryer

To analyze the influences of drying conditions inside a cylinder dryer such as temperature and humidity fields and flow field during cut tobacco drying, these parameters were studied via numerical simulation. The accuracy of the simulated results was verified by measuring the air humidity inside the cylinder through a drying experiment, and the influences of the temperature and velocity of hot air at inlet, wall temperature and rotation speed of the cylinder on the moisture distribution inside the cylinder during drying were investigated. The results showed that: 1) The rise of hot air temperature at the inlet accelerated evaporation process. 2) The speedup of hot air velocity at the inlet enhanced moisture evaporation in the front section of the cylinder. However the overall moisture concentration inside the cylinder decreased if the hot air velocity at the inlet was too high. 3) The variation of cylinder wall temperature directly affected cut tobacco's temperature and equilibrium moisture content inside the cylinder, which increased with the rise of cylinder wall temperature. 4) The increase of cylinder rotation speed reduced the residence time of cut tobacco in the cylinder, which was not conducive to cut tobacco drying.