竖直管降膜蒸发器流动与传热过程的数值模拟

针对竖直管降膜蒸发器的技术特点,在计算流体力学和传热学理论分析基础上,采用FLUENT软件,运用自定义函数(UDF)编写传质源项,对降膜蒸发器的加热管内液体沿壁面呈膜状下降流动并受热汽化过程进行了三维数值模拟研究,模拟采用Mixture两相流层流模型,Simple算法。模拟结果以3D形式表现了液体沿运动方向在管壁发展成膜的过程,并将模拟得到的液膜厚度与理论计算得到的液膜厚度进行了比较。模拟结果表明,竖直降膜蒸发器加热管具有液膜薄,均匀性好的特点,管表面容易形成柱状流,液膜厚度为1.0 mm。

Numerical Simulation of the Flow and Heat Transfer Process of Vertical Tube Falling Film Evaporator

In this paper, theoretical analysis and Computational Fluid Dynamics （CFD） study on falling film process of vertical heating tube for falling film evaporator＇ s heat transferring was conducted. A three- dimensional numerical simulation of falling film flow was made using FLUENT software which had been further exploited with user defined functions （UDF） to identify the source term of mass and heat transfer. We studied the falling film evaporating and heat of vaporization process of heating liquid membranous fall- ing along the wall. We adopted two-phase flow Mixture model and laminar flow model, Simple algo- rithms. The simulation results was in 3D performance of the liquid along the direction of movement of the development process of the film formation in the wall, the film thickness was calculated and compared with the theoretical and simulated. The simulation results show that the heating tube of vertical falling film evaporator with the good uniformity characteristics of thin liquid film and the tube surface is relatively easy to form columnar flow. The results show the film thickness is 1.0 mm.