柔性中空纤维膜管悬垂、振动及其热质传递机理研究

The hollow fiber membrane contractor is widely used in many engineering fields due to high efficiency and compact structure. The hollow fiber tubes were usually assumed rigid tubes without considering the curve and vibration behaviors in previous research. However, the intrinsic curve and vibration behaviors play an important role in the performance of the hollow fiber membrane contractor. The mechanism of the flow and heat/mass transfer process under curve and vibration conditions is unclear. Therefore, this project aims at investigating the curve and vibration behaviors of the hollow fibers, as well as its effect on the heat and mass transfer performance. Firstly, the characteristics of the curve and vibration behaviors are investigated using fluid-solid coupling analysis. The models of curve and vibration behaviors for hollow fiber membrane tubes and bundles are established to investigate the effect of gas and liquid flow rates and elasticity modulus on curve and vibration parameters, such as deflection, frequency and amplitude. Then, the flow and heat/mass transfer models under curve and vibration conditions are developed to investigate the effect of deflection, frequency and amplitude on Nusselt number, Sherwood number and friction factor, etc. Finally, the mechanism of curve and vibration behaviors in enhancing the heat and mass transfer performance of the hollow fiber membrane contractor is comprehensively investigated. This research could provide guidance in the optimization of hollow fiber membrane contractors.

中空纤维膜以其高效分离、结构紧凑等优点在工农业各领域得到了广泛的应用。以往的传热传质研究都采用了刚性膜管的假定，不考虑膜管的悬垂与振动。但柔性膜管固有的悬垂与振动对膜组件的性能有重要影响，其对流动和传热传质的影响机理亟待探寻。因此，本项目拟采用理论分析、数值模拟和实验测量的手段研究柔性中空纤维膜管的悬垂与振动规律及其对流动和传热传质的影响。首先从膜管与管外气流和管内液体的相互作用出发，认识膜管和管束的悬垂与振动规律，建立柔性中空纤维膜单膜管和管束的悬垂与振动模型，分析气、液流速、弹性模量等参数对挠度、振动频率和振幅等悬垂和振动参数的影响。在此基础上，建立悬垂和振动条件下的流动和热质传递模型，分析挠度、振动频率和振幅等参数对努塞尔数（Nu）、舍伍德数（Sh）和阻力因子的影响。最后，探索悬垂和振动对强化热质传递的影响。研究成果可为实际运行工况下膜组件的优化设计提供理论支持。

中空纤维膜是膜分离的基础材料，它在工农业各领域都有广泛的应用，尤其在建筑环境除湿领域有着重大需求。中空纤维膜在液体重力和气流冲刷的共同作用下容易发生弯曲和变形，膜管的振动和变形对流体流动以及传热传质都有重要的影响，但目前对流致振动状态下中空纤维膜管的传热传质研究还存在不足。因此，本项目首先运用任意拉格朗日-欧拉法（ALE）建立了流致振动状态下中空纤维膜管两相流固耦合模型，搭建振动试验台通过测定中空纤维膜管在流体作用下的位移验证模型的正确性。在上述流固耦合模型的基础上，加入能量方程和组分传递方程建立起流体诱导纤维膜振动的双向传热传质流固耦合模型，研究脉动流体的振幅和频率对中空纤维膜传热传质性能的影响。通过对近壁面的流场、温度梯度、浓度梯度的分析研究流致振动强化中空纤维膜传热传质的内部机理。得到了在流体作用下弯曲的中空纤维膜的三维模型，建立了包含多根弯曲管的中空纤维膜管束模型并研究在不同风速状态下中空纤维膜管束传热传质的速度场、温度场、浓度场，通过摩擦系数、努塞尔数和舍伍德数来表征其流动和对流传热传质能力，阐明弯曲管对传热传质的影响规律。近三年来，本项目研究严格按照计划进行，完成了预定的全部研究内容，取得了预期的结果。本项目在Physics of Fluids、Desalination、Energy and Buildings等领域内著名期刊共发表SCI论文12篇，申请发明专利2项，实用新型专利1项；协助培养硕、博士毕业生4人，培养博士后1名；参加全国工程热物理年会3次，国际会议1次，邀请国际知名学者讲学1次。项目执行期间项目负责人入选了广东省“珠江人才计划”海外青年人才引进计划、广州市科协“青年科技人才托举工程”。超额完成了任务书目标。