太阳能膜蒸馏海水淡化系统的传热传质特性与热力过程模拟

The heat and mass transfer characterization and thermodynamics simulation of systems coupling membrane distillation and solar energy for seawater desalination are of significant importance in scientific research and engineering application. This project proposes a solar energy system driven by hollow fiber membrane distillation for seawater desalination. It uses a hydrophobic-hydrophilic composite membrane to realize non-contacting air humidification, to completely avoid air pollution due to water drop splash. The proposed system uses hot seawater for air heating and humidifying in the membrane distillation, and adopts cold seawater for air cooling and dehumidifying in the finned tube evaporator. Thus the coefficient of performance is improved. In this project, the thermodynamic and dynamic performances of the system and the transport properties in the membrane module will be investigated, concentrating on investigating the influence of the evolution law of thermodynamic state of the heat and mass transfer processes of the membrane distillation system. The investigation will include: establishing the steady state and dynamic thermodynamic model of the system, understanding the role mechanisms of various design and operating conditions on the efficiency of the system, clarifying the energy matching relationship for each component, and revealing the energy saving principle for the system; The research will establish a dynamic model coupling heat and mass transfer for the membrane modules "liquid-membrane-gas" system, reveal the flow and heat transfer mechanisms in the randomly distributed hollow fiber membrane bundle using the fractal theory, and clarify the heat and mass transfer enhancement mechanism of the components; The project will analyze the system static and dynamic characteristics, explore the maximizing optimization of the system model , and investigate the system of dynamics and thermodynamic optimization theory. The above mentioned researches will lay a solid theoretical foundation of the system's industrialization.

太阳能膜蒸馏海水淡化系统的传热传质特性与热力过程模拟对科学研究和工程应用具有重要意义。本项目提出一种太阳能驱动的中空纤维膜蒸馏海水淡化系统，它采用一种亲水/憎水复合膜将海水与处理空气隔开，避免了空气带液飞沫污染。用膜蒸馏实现热海水对空气加热加湿，用冷海水对空气冷却除湿，提高系统能效。项目将对该系统的热力学特性和膜组件的传递动力学特性开展研究，研究系统中对膜蒸馏传热传质过程的热力状态演变规律的影响，研究包括：建立系统的稳态和动态热力学模型，认识各种设计和操作条件对系统效率的作用机理，阐明各部件能量匹配关系，揭示系统节能原理；建立膜组件中“液-膜-气”体系的热质耦合传递动力学模型，用分形理论揭示随机分布的中空纤维膜管束在过渡流状态下的流动与传递规律，阐明组件传递强化机理；分析系统静态与动态特性，探索系统模型极值优化，研究系统热力学与动力学优化原理。上述研究将为该系统的实用化夯实理论基础。

利用太阳能进行海水淡化是合理利用低品位能源获得淡水的重要方式，具有广泛的应用前景。本项目创新性的采用一种亲水/憎水复合膜将海水与处理空气隔开，避免了空气携带小液滴对水质的污染。中空纤维膜加湿器作为海水淡化过程的关键部件，建立了加湿器在层流、过渡态湍流、湍流流态下的耦合传热传质数学模型。研究了流体的流动特性以及海水和空气之间通过多孔膜进行耦合传热传质过程，揭示了流动与热质传递参数对系统效率的作用机理。建立了太阳能膜蒸馏海水淡化系统的热力学数学模型，研究了设计与运行条件对系统性能的影响规律，建立了太阳能膜蒸馏海水淡化系统的热力学优化模型，揭示了海水淡化系统的最优状态参数，阐明系统的多参数优化机理。上述研究为太阳能膜蒸馏海水淡化系统的实用化打下良好的理论基础。