木纤维脉冲-旋流气流干燥气固两相流分析及数值模拟

通过对脉冲-旋流气流干燥气固两相流分析及数值模拟的研究,采用欧拉-拉格朗日模型和计算流体力学软件Fluent对脉冲-旋流气流干燥机内部的气固两相流场进行了三维模拟,揭示脉冲-旋流气流干燥木质纤维的机理和传热传质特性。结果表明,加载物料后的气流速度变化明显,并且物料与气流速度有2 m/s左右的速度差,有利于传热传质。气流速度越大,物料停留时间越短。进料速度的增加会在旋流干燥器底部形成一个回流区,易造成物料的返流,并增加了物料在干燥机停留时间。通过对计算出的温度、速度、时间的曲线与实测值进行对比,二者最大相对误差小于10%,验证了fluent气固两相流模拟方法建立的脉冲-旋流气流干燥过程的数学模型是有效的。

Gas-solid Two-phase Flow Analysis and Numeric al Sim ulatio n of th e Impulse-cyclone Airflow Drying

Through gas-solid two-phase flow analysis and numerical simulation of the impulse-cyclone airflow drying,the Euler-Lagrange model and computational fluid dynamics software Fluent were applied to simulate the gas-solid two-phase flow field to reveal the mechanism of drying and heat and mass transfer properties.The airflow velocity changed obviously and 2 m/s velocity difference between fibers and airflow showed in the simulation,which was advantageous to the heat and mass transfer.The increase of feed speed led to a backflow area at the bottom of cyclone dryer,which easy to cause reflux of the material and long residence time of the wood fibers in the dryer.By calculating the curve of the temperature,speed,time compared with the measured values, the maximum relative error between simulation and test was less than 10%, which verified gas-solid two phase flow method of Fluent to establish the mathematical model of impulse-cyclone airflow drying was effective.