Abstract: The evaporation process of brine solution under reduced pressure is widely used in areas such as desalination and industrial salting, so it is meaningful to study the evaporation characteristics of a saline droplet during depressurization, which can effectively solve water shortage in China. This work studied the salting process of brine droplet evaporation under reduced pressure by numerical simulation, and obtained the variations of droplet temperature and salting quality with time. The working fluid was saturated brine, the initial temperatures of drops were 20℃, 15 ℃ and 10℃ respectively, and the environmental pressure changed from 0.1MPa to 2000—10000Pa. Comparing numerical results with experimental data, the validity of this model was achieved. Through numerical calculations, the main factors affecting salting rate and droplet temperature variation were analyzed. With a larger droplet diameter, salting rate during evaporation was higher, but temperature change was slower. While with faster pressure dropping rate, droplet evaporation rate would be faster, salting rate would be faster, and also droplet temperature would change faster. With a higher droplet initial temperature, evaporation rate would be higher, and salting rate would be higher, but the final temperatures of brine droplets with different initial temperatures approached the same value during evaporation process.

Key words: depressurized evaporation, salting out, numerical simulation, droplet

摘要： 盐水溶液的降压蒸发广泛应用于海水淡化和工业制盐等领域,因此研究盐水在降压过程中的蒸发特性具有重要意义,有助于解决我国水资源缺乏问题。本文通过数值模拟的方法研究了降压环境下盐水液滴蒸发析盐过程,获得了盐析质量和液滴温度随时间的变化。采用的工质为饱和盐水,液滴的初始温度分别为20℃、15℃、10℃;环境压力从0.1MPa降至2000～10000Pa。通过与实验数据相对比,验证了本文模型的有效性。通过该数学模型,分析了影响析盐率和液滴温度变化的主要因素。结果表明:液滴直径越大,在蒸发过程中其析盐率越高,但温度变化越慢;压降速率越快,液滴蒸发速率越快,析盐率越大,温度变化也越快;液滴初始温度越高,蒸发速率越快,液滴表面析盐率越高,但不同初始温度的盐水液滴,在蒸发过程中其最终温度趋于一致。

关键词: 降压蒸发, 盐析, 数值模拟, 液滴