A Dynamic Flash Evaporation and Vapor Separation System for Seawater Desalination

全世界都缺乏饮用水。特别是在沿海地区，对大量可用的海水进行脱盐是将海水转化为淡水的一个可行选择。过去已经制定了许多淡化海水的方案。然而，这些方案要么是能源密集型的，要么是资本密集型的。因此，生产饮用水的成本相对较高。该项目将开发、分析和优化一种新型的高通量海水淡化技术，该技术紧凑、模块化，建造和运营成本相对较低。在这项技术中，来自太阳能池的太阳能加热海水流经一组注入器通道，在那里水变得过热，导致蒸汽泡的形成。气泡的形成加速了压降，使更多的热能转化为蒸汽。汽液混合物从喷射器通道切向进入一个更大的管。由于涡流产生的离心力使液体向外移动，而蒸汽在分离管中间形成一个核心。蒸汽通过回收管离开蒸汽芯到冷凝器以产生饮用水。分离的液体被泵回太阳能池重新加热。研究小组已在实验室证明该概念的可行性，现正建议扩大实验工作，以证明该概念在更广泛的操作参数范围内的适用性。热转换效率、蒸汽分离效率以及喷射器通道和分离器管内的温度和压力分布数据将得到。这些数据将用于支持该过程的分析和数值模拟。在多种质量通量和动量通量条件下，测量了分离管内的空隙率，研究了分离管内汽芯的稳定性。这是一个以前未被探索过的领域，在有意义的实验和分析/数值建模方面代表了一个重大的智力挑战。所获得的知识将用于优化热转换效率和蒸汽分离效率在一系列流动条件和温度的水退出太阳能池。最后，实验工作将用于开发一个操作地图，该地图可能对在大气和亚大气压力下实际实施这一新概念具有重要价值。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

There is a worldwide scarcity of potable water. Desalination of abundantly available seawater especially in coastal areas offers a viable option for conversion of seawater into fresh water. A number of schemes for desalination of water in the past have been developed. However, these schemes are either energy intensive or capital intensive. As a result, the cost of production of potable water is relatively high. The project will develop, analyze, and optimize a novel high-throughput desalination technique that is compact, modular, and relatively inexpensive to build and operate. In this technique solar-heated sea water from a solar pond flows through a set of injector passages, where the water becomes superheated leading to formation of vapor bubbles. Formation of bubbles accelerates the pressure drop allowing more thermal energy to be converted into vapor. The vapor-liquid mixture exits the injector passages into a larger tube tangentially. Centrifugal force generated as a result of swirl causes liquid to move outward while vapor forms a core in the middle of the separator tube. Vapor leaves the vapor core via a retrieval tube to a condenser to create potable water. Separated liquid is pumped back to the solar pond to be reheated. Having demonstrated the viability of the concept in the laboratory, the team is proposing to expand the experimental work to demonstrate the applicability of the concept over a broad range of operational parameters. Data for thermal conversion efficiency, vapor separation effectiveness and temperature and pressure profiles in the injector passages and separator tube are to be obtained. The data will be used to support analytical and numerical modeling of the process. Void fraction in the separator tube is to be measured and stability of vapor core in the separator tube will be investigated under a variety of mass and momentum flux conditions. This is an area unexplored before and represents a significant intellectual challenge with respect to meaningful experiments and analytical/numerical modeling. Gained knowledge will be used to optimize thermal conversion efficiency and vapor separation effectiveness under a range of flow conditions and temperatures of water exiting the solar pond. Lastly experimental effort will be used to develop an operational map that could be of great value for practical implementation of this novel concept at atmospheric and sub-atmospheric pressures.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.