板式降膜低温多效海水淡化数值与实验研究

发布时间：2018-05-24 16:36

本文选题：海水淡化 + 板式降膜　；参考：《浙江大学》2015年硕士论文

【摘要】：水是一切人类文明的源泉,人类社会的活动和发展离不开水。当前,全世界半数以上的江河湖海都面临着水量急剧降低、污染加重等问题,全球四成左右的人口都处于严重缺水的危机之中。未来的30年,全球将有超过55%的人面临水荒危机。我国当前有16个省的人均水资源占有量低于严重缺水线,其中6个省处在极度缺水线之下。沿海地区海水资源丰富,从大海中提取淡水成为解决沿海地区淡水资源紧缺最为现实的选择。水电联产在实现电厂余热的综合利用的同时,利用其公共的取水、输水设备,有利于降低海水淡化的生产成本,极大的缓解我国北方沿海的淡水资源紧张问题,使电厂从传统的耗水大户变成了供水大户,具有重要的经济和社会价值。本文提出板式降膜低温多效海水淡化方法,利用Fluent软件研究降膜流动的水动力特性,分析了液膜的波动和三维流动特性,获得了液膜厚度的关联式δ=0.2805Re0.5017(v2/g)1/3,R2=0.99742。研究了液膜破裂及其演化过程,预测了两种不同进料方式下液膜破裂的临界流量,与试验结果吻合度较好。建立板式降膜换热试验台,考察液膜的换热特性,获得了降膜流动的换热关联式。层流与湍流转折点：Recr=5760Pr-1.093;层流区：h+=0.823Re-0.352,ReRecr；湍流区：h+=0.0038Re0.42Pr0.66,ReRecr。基于以上研究,建立板式降膜低温多效海水淡化系统参数设计模型,针对多效海水淡化系统计算的复杂性和非线性性,充分考虑水、水蒸气及海水物性随温度和浓度的变化和整个蒸发过程的温度损失,基于物料平衡和能量平衡利用Matlab软件编写适用于降膜低温多效海水淡化的计算程序。建立三效低温多效海水淡化实验试验台,对产水量、温度分布、造水比等重要性能参数从加热蒸汽、进料温度、进料流量、冷却水温度、冷却水流量等方面做了系统的分析。加热蒸汽量增加,系统整体温度提高,淡水产量增加、造水比下降；随着进料温度升高、进料流量下降,淡水产量和造水比都相应增加；冷却海水流量增加、冷却海水温度降低,系统的冷却能力提高,各效对应的温度降低,淡水产量和造水比都提高。在设计工况下,产水产量约为10kg/h,造水比可达2.45。
[Abstract]:Water is the source of all human civilization, the activities and development of human society can not be separated from water. At present, more than half of the world's rivers, lakes and seas are faced with problems such as the sharp reduction of water volume and the worsening of pollution. About 40% of the world's population is in the crisis of serious water shortage. Over the next 30 years, more than 55% of the world's population will face a water shortage crisis. At present, there are 16 provinces in China, the per capita water resource is lower than the serious water shortage line, and 6 provinces are below the extreme water shortage line. The coastal area is rich in sea water resources, so extracting fresh water from the sea becomes the most realistic choice to solve the shortage of freshwater resources in coastal areas. In order to reduce the production cost of seawater desalination and alleviate the shortage of fresh water resources in the northern coastal area of China, hydropower co-generation can realize the comprehensive utilization of waste heat in power plants, at the same time make use of its public water intake and water conveyance equipment to reduce the production cost of seawater desalination. It is of great economic and social value to change the power plant from a traditional water user to a large water user. In this paper, a plate falling film low temperature multi-effect desalination method is proposed. The hydrodynamic characteristics of falling film flow are studied by Fluent software. The fluctuation and three dimensional flow characteristics of liquid film are analyzed. The correlation equation 未 0.2805 Re0.5017v / 2 / 1 / 3 / R2U 0.99742is obtained for the thickness of liquid film. The film rupture and its evolution process are studied, and the critical flow rate of liquid film rupture under two different feeding modes is predicted, which is in good agreement with the experimental results. The heat transfer correlation of falling film flow was obtained by investigating the heat transfer characteristics of liquid film on a plate-type falling film heat transfer test rig. The laminar flow and turbulence turning point Recr-5760Pr-1.093; the laminar flow zone: 0.823Re-0.352 ReRecr; the turbulent zone: 0.0038Re0.42Pr0.66; the laminar flow zone: 0.0038Re0.42Pr0.66. Based on the above research, the parameter design model of plate falling film low temperature and multi-effect seawater desalination system is established. Considering the complexity and nonlinearity of multi-effect seawater desalination system, water is fully considered. The physical properties of water vapor and seawater vary with temperature and concentration and the temperature loss of the whole evaporation process. Based on the material balance and energy balance, a calculation program is developed by using Matlab software for multi-effect seawater desalination at low temperature and low temperature. A three-effect low temperature and multi-effect seawater desalination test rig was set up. The important performance parameters such as water production, temperature distribution and water ratio were systematically analyzed from the aspects of heating steam, feed temperature, feed flow rate, cooling water temperature, cooling water flow rate and so on. With the increase of heating steam quantity, the whole temperature of the system increases, the fresh water output increases, and the ratio of water to water decreases; with the increase of the feed temperature, the feed flow rate decreases, and the fresh water output and water ratio increase accordingly; the cooling seawater flow rate increases, The cooling capacity of the system increases with the decrease of cooling seawater temperature, the corresponding temperature of each effect decreases, and the fresh water yield and the ratio of water to water are increased. Under the design condition, the yield of water is about 10 kg / h, and the ratio of water to water is 2.45.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P747

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