喷雾蒸发海水淡化的数值模拟

发布时间：2018-03-06 10:34

本文选题：气旋型喷雾干燥塔　切入点：数值模拟　出处：《中国民航大学》2014年硕士论文　论文类型：学位论文

【摘要】：全球性水危机日益加剧。我国水资源更是严重短缺,南北水资源分布不均。发展海水淡化技术是可以有效缓解当前水危机的重要措施。喷雾蒸发海水淡化技术是一种新型的海水淡化技术,它将海水喷雾蒸发得到水蒸气,再将水蒸气冷凝后得到淡水。该技术提高了海水的产水量和回收率,具有规模灵活,设备投资适中,可利用低位热能等优点。用太阳能,这一清洁绿色能源作为热源的喷雾蒸发海水淡化技术已经成为未来海水淡化技术发展的主要方向。本文自主设计了太阳能喷雾蒸发海水淡化系统原理图。通过对该工作过程的分析,得出了最大的难点在于喷雾蒸发室的喷雾干燥过程。为了详细了解喷雾蒸发室的喷雾干燥过程,以及提高喷雾蒸发室的干燥效率。采用数值模拟的办法用Fluent软件对喷雾蒸发过程进行仿真模拟。本文重点模拟气旋型喷雾干燥塔内的喷雾蒸发过程。基于breakup和collision液滴破碎模型采用Fluent和Gambit软件对气旋型喷雾干燥过程进行了数值模拟,得到了干燥过程中干燥塔内流场、速度、温度分布情况,以及颗粒运动直径变化和停留时间等信息。模型还分析了进风温度、风速、料液温度及重力等因素对蒸发效率的影响。得出了如下结论:1、进风温度越高,蒸发效率越高。当进风温度达到473K后,再提高进风温度,对干燥塔的整体蒸发效率提高作用不大;2、进风速度越快,干燥效率越高。当速度达到20m/s后,速度再提高,干燥效率显著减小;3、提高料液的预温度和将干燥塔倒置,这两种方法对整体的喷雾蒸发效率影响很小;4、考虑到Fluent自带的喷嘴模型的雾化颗粒均匀性不够高,在实际生产中,通过使用高技术喷嘴,提高颗粒的均匀性,将大大提升雾化干燥的效率。以上结论,为气旋型喷雾干燥塔的优化设计和干燥效率的提高提供了理论依据,为下一步模拟盐雾分离的模拟,垫定基础。
[Abstract]:The global water crisis is worsening day by day. The development of seawater desalination technology is an important measure to alleviate the current water crisis. Spray evaporation desalination technology is a new desalination technology. After condensing water vapor, fresh water is obtained. The technology improves the water production and recovery rate of seawater, has the advantages of flexible scale, moderate investment in equipment, utilization of low thermal energy, and so on. The spray evaporation desalination technology of clean green energy as a heat source has become the main direction of seawater desalination technology in the future. The principle diagram of solar spray evaporation desalination system is designed in this paper. The analysis of the working process, In order to understand the spray drying process of spray evaporation chamber in detail, the biggest difficulty is the spray drying process of spray evaporation chamber. The method of numerical simulation was used to simulate the spray evaporation process with Fluent software. In this paper, the spray evaporation process in cyclone spray drying tower was simulated emphatically. Based on breakup and collision, the spray evaporation process in the cyclone spray drying tower was simulated. The droplet breakage model was used to simulate the cyclone spray drying process using Fluent and Gambit software. The flow field, velocity, temperature distribution, particle movement diameter and residence time in the drying tower were obtained. The model also analyzed the inlet air temperature and wind speed. Effects of feed temperature and gravity on evaporation efficiency. The following conclusion is drawn: the higher the inlet air temperature, the higher the evaporation efficiency. When the inlet air temperature reaches 473K, the inlet air temperature is raised. It has little effect on the overall evaporation efficiency of the drying tower, and the faster the inlet air speed, the higher the drying efficiency. When the speed reaches 20 m / s, the drying efficiency will be increased, the drying efficiency will be significantly reduced, the pretemperature of the material solution will be increased and the drying tower will be inverted. The effect of these two methods on the overall spray evaporation efficiency is very small. Considering that the atomization particle uniformity of the nozzle model brought by Fluent is not high enough, the uniformity of the particles can be improved through the use of high-tech nozzles in actual production. The above conclusion provides a theoretical basis for the optimization design of cyclone spray drying tower and the improvement of drying efficiency, and provides the basis for the next simulation of salt spray separation.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P747

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