反电渗析发电传质过程建模及离子输运特性研究

Power generation by reverse electrodialysis has become the important direction of the field of new energy resource in the future with respect to its peculiar advantages of low cost, renewability and none pollution to environment and so on. For the current state of low power density and energy efficiency as well as indistinct ion transport mechanism and its influence on the power-generation characteristic in reverse electrodialysis, the investigation on the modeling of mass-transfer process and ion transport characteristic for power generation by reverse electrodialysis is developed in this project. First, the evolution of power-generation characteristic and its key influencing factors are studied experimentally for different operational conditions and membrane stack parameters and the internal relation between the ion transport and performance of power generation is obtained. The matching relation between operational condition and membrane stack parameter for the best performance of power generation is established. Then, the mass transfer model for reverse electrodialysis is developed with the coupling between multiple physical fields and ion migration within the membrane considered, in which the microscopic ion transport mechanisms in reverse electrodialysis and its influencing mechanism on the power-generation characteristic are revealed. Moreover, with the evolution of concentration polarization effect at the surface of ion exchange membrane studied for different conditions by the mass transfer model, the influence of concentration polarization on the characteristics of ion transport and power generation is revealed and meanwhile, the suppressing method of concentration polarization is pursued. Finally, based on the experiment and simulation analysis, the important basis for the enhancement of performance of power generation and structure optimization for reverse electrodialysis is formed.

反电渗析发电具有成本低、可再生、对环境零污染等优势，是未来新能源领域的重要发展方向。针对当前反电渗析发电功率密度和能量效率较低以及离子输运机理及其对产电特性影响尚不清晰的现状，本项目拟开展反电渗析发电传质过程建模及离子输运特性研究。首先，实验研究不同运行条件和膜堆参数情况下反电渗析产电特性的变化规律及其主要影响因素，获得离子输运和产电性能之间的内在联系，建立最优产电性能下运行条件和膜堆参数之间的匹配关系。其次，建立考虑膜离子迁移与多物理场相耦合的反电渗析传质模型，揭示反电渗析微观离子输运机理及其对产电特性的影响机制。同时，研究不同条件下离子交换膜表面浓差极化效应的演变规律，揭示浓差极化对反电渗析离子输运和产电特性的影响，探求抑制浓差极化效应的方法。最后，基于实验和仿真分析形成反电渗析产电性能提升和结构优化所需的重要依据。

反电渗析发电具有成本低、可再生、对环境零污染等优势，是未来新能源领域的重要发展方向。针对当前反电渗析发电功率密度和能量效率较低以及离子输运机理及其对产电特性影响尚不清晰的现状，本项目开展了反电渗析盐差发电传质过程建模及离子输运特性的研究。通过搭建反电渗析膜堆电化学特性测试平台，实验研究了基于传统隔板和离子导通隔板的反向电渗析盐差膜堆装置产电特性的变化规律及其关键影响因素，获得了不同膜堆构型（离子交换膜种类、膜对数量、隔板孔径以及流道形状）和运行条件（进料液浓度、流速）下膜堆开路电压、电阻和功率密度等电化学参数的变化规律，归纳总结了影响反向电渗析产电特性的关键因素；建立了最优产电性能下运行条件与膜堆构型之间的匹配关系，为反向电渗析系统的设计与优化提供指导。综合考虑浓度变化和膜离子迁移过程的相互耦合作用，建立了基于物料平衡的反电渗析传质过程数学模型，仿真研究了不同工况下膜堆开路电压、电阻和功率密度，并进行实验验证；分析了浓度和温度对溶液离子扩散系数的影响，获得了极限电流密度、离子迁移时间和迁移数等输运特征参数表征方程及其随浓度、流速的演化规律。通过耦合不同电化学测量方法测量了不同条件下膜-溶液系统中极限电流密度、迁移时间、迁移数和扩散边界层厚度，获得了离子交换膜表面微观离子迁移过程和浓差极化的演化规律，揭示了浓差极化对膜-溶液系统离子输运和产电特性的影响机制，获得了浓差极化效应的抑制方法。本项目的研究结果对反电渗析盐差发电产电特性提升及浓差极化抑制提供了所需的重要依据，形成了一套反电渗析离子输运和产电性能研究的新技术，为未来高效反电渗析发电系统的设计和优化奠定了理论指导。