多孔碳微球对基于空化效应的海水淡化的影响研究

Fresh water is essential to the survival of mankind. Currently, the global fresh water resources are not sufficient enough to supply human beings. For many decades, scientists and researchers are keeping looking to develop low energy consumption, low cost, high efficiency way of desalination. Cavitation is a normal hydraulic phenomenon. During cavitation process, enormous energy will be released, and wasted. According to the previous research result, this energy can be used in desalination. Meanwhile, basing on the research results about the particle addition into cavitation process, by adding particles as small as tens to hundreds micrometers, the cavitation field would be homogenized, and the cavitation intensity would be enhanced, which means that the energy released during cavitation would also be increased. Yet, there is no report about increasing the desalination effect by adding micro particles by cavitation method. Here, in this project, we are planning to synthesize porous micro carbon particles by microfluidic method with various diameters and porosities. By adding the synthesized micro particles, the NaCl concentration before and after cavitation will be compared, and the relationship among the diameter of the particle, the porosity of particle and the concentration change of NaCl will be established. Moreover, by comparing the theoretical result predicted by the obtained relation and the experimental result, the numerical result will be further revised. In the microfluidic synthesize process, the size of the particle will not be controlled by the usual W/O controlling method. We will control the size of the particle by changing the water content in the droplet, since the particle will shrink after evaporation of the water contained in the droplet. This is a new way to control the size of the particle synthesized by the microfluidic method. Above all, this research will offer a way to enhance the desalination effect, which is meaningful for the realization of low-cost, low-power, and high-efficiency desalination.

淡水是人类赖以生存和发展的基本物质之一。目前，地球上淡水资源不足。如何实现低耗能、低成本、高效率的海水淡化一直是人类的探索目标。空化是一种常见的水力现象，空化过程中将释放巨大的能量。已有研究表明，利用空化产生的能量，可实现海水淡化。同时有研究表明通过在液体中添加微米级颗粒，可以使空化场均匀，空化强度增强，释放的能量增加。然而，有关添加微米级多孔颗粒，对海水淡化效果的影响尚未见有所报道。本研究拟通过微流体方法，合成不同直径、不同孔隙率的微米级多孔碳小球。通过比较空化前后NaCl浓度的变化，分析其对海水淡化效果的影响，并建立起三者之间的数学模型。通过理论与实验相结合的方法，对模型进行验证和修正。其中，多孔微米碳颗粒尺寸，本研究拟通过控制液滴中的含水量对加热后的固体颗粒尺寸进行控制，不采用传统的控制不同相之间的流速比，控制液滴大小的方法。研究对于实现低成本、低能耗、高效率的海水淡化具有重要意义。

传统海水淡化方法包括离子交换法，反渗透膜法以及多级闪蒸方法，虽然可以达到比较高的海水淡化率，但如何提高海水淡化的效率，可以实现低耗能、低成本、高效率的海水淡化一直是人类的探索目标。空化是一种常见的水力现象，空化过程中会释放巨大的能量。本课题研究中，通过微流体方法实现了合成大小、孔隙可调的均一化多孔微颗粒；并研究了颗粒大小对盐度的影响。实验结果表明：利用空化产生的能量可以加速离子交换的速度，提高海水淡化的效率。并且，颗粒直径在20-70 μm范围内，可以有效降低海水盐度。当粒径小于20 μm时，颗粒易出现团聚现象；当颗粒直径大于70 μm时，颗粒分散不均匀，易沉积到容器底部。.本课题主要研究了空化对于利用离子交换方法实现海水淡化的影响。实际上由于空化效应所产生的巨大能量，结合目前海水淡化的主要实现手段，有可能利用空化产生的高压，减少反渗透膜海水淡化技术的能量消耗，提高效率；或利用空化产生的高温，减少多级闪蒸海水淡化技术的的能量消耗，提高效率。总之，空化伴随着巨大的能量产生，尝试控制和利用空化能量，是值得进一步深入研究的课题。