太阳能驱动的中空纤维膜液体除湿系统的热动力学研究

This project is proposed the solar energy powered hollow membrane-based liquid desiccant air dehumidification system. In this system, the diluted solution can be regenerated by solar energy. The hollow membrane modules are used to replace the traditional dehumidifier and regenerator. In these modules, semi-permeable membranes were used to separate the desiccant solution and the process air from each other. The membranes were able to prevent the solution from crossing over to the process air, while selectively permitting the transport of heat and moisture between the solution stream and the air stream. The present researchers are focus on the feasibility of the system. However, there are no literature reports on the further theoretical and experimental investigation. In this project, the methodology is a combination of experiments, theoretical analysis, mathematical modeling to further study the thermodynamic problem of the proposed system. The heat and mass transfer of membrane modules under tube bundle bending are conducted. The thermal cycle of the proposed system is built. The performances of the proposed system are analyzed. The dynamic state mathematical models are built. Based on the dynamic state mathematical models, the dynamic performances of the proposed system are investigated. The capacity matching of components are analyzed. The system and the component will be optimized from thermodynamic levels. Base on the theoretical analysis, the thermodynamic and optimal theory and guidelines are made to promote the system industrialization.

太阳能驱动的中空纤维膜液体除湿系统是利用太阳能来再生盐溶液，利用中空纤维膜来解决液滴夹带问题，同时实现空气的液体除湿，以代替传统的吸收器和再生器。目前对该系统的研究主要是集中在系统的节能可行性研究方面，没有对系统进行理论和实验研究。本研究采用理论计算与实验相结合的研究方法，研究中空纤维膜管束随机分布弯曲情况下空气绕流管束的流动与共轭传热传质机理，构建系统的热力学循环，揭示系统的热力学循环机理；建立系统的动态热力学模型，揭示太阳能驱动的中空纤维膜液体除湿空调系统的运行特性；研究系统各部件的匹配关系，对部件和系统进行优化，形成太阳能驱动中空纤维膜液体除湿系统的热力学设计理论和优化方法，促进系统的产业化。

本项目研究了太阳能驱动的中空纤维膜液体除湿系统的热力学性能。建立实验台研究了中空纤维膜组件内的流场特性，并使用CFD软件对组件内的流场做了进一步的研究。建立太阳能驱动的中空纤维膜液体除湿系统的实验台，对系统的除湿和加湿性能进行了研究。建立了系统的数学模型，研究了参数变化对系统的性能的影响，分析了各部件的㶲损失，揭示了系统的热力学循环机理。结合Transys 软件，建立了系统的动态模型，分析了系统的动态运行特性。利用多目标粒子群算法对部件除湿组件和加湿组件进行研究，得出了组件的优化几何参数。经过四年的研究，本项目初步得出了除湿系统的热力学设计理论和优化方法。本项目使用的中空纤维膜的屈服强度和抗拉伸强度大小分别为3 MPa和12 MPa；当屈强比为0.25左右时，断裂伸长率在330%上下浮动，此时的弹性模量大小为60 MPa左右。总体而言，中空纤维膜的抗拉伸强度和断裂伸长率均较大，弹性模量较小。管与管之间的流场基本为同一速度，管的周围可以看到明显的分层现象和部分速度相等的闭合区域。溶液温度与太阳辐照度有关，因此在12:00-13:00时刻系统的除湿量、除湿效率和各组件㶲损最大。此外太阳能集热器的火用损占总火用损的比例最大，提高太阳能集热器的利用率能够有效减少除湿系统的不可逆损失。组件内总热通量和水蒸气透过量最大时通常对应最大熵产和㶲损，增大热质传递的驱动力会导致熵产和㶲损也随之增大。通过粒子群优化算法研究了纤维数、纤维长度、纤维内径、填料率等几何参数对总熵产和年总成本的影响。结果表明，影响中空纤维膜基液体干燥剂模块性能的最重要因素是纤维的内径。.研究过程发表了SCI论文5篇，2篇EI论文，3篇核心期刊论文，申请了6项实用新型专利，1项发明专利获得授权。