Abstract:

Based on the remarkable heat transfer performance of heat pipe (HP) and great specific surface area of small diameter droplets, HP and spray technologies are used in a novel single stage vacuum evaporator. And man-made seawater with 3% saltness is tested. Parameters affecting the performance such as temperature of cold source and heat source, spray temperature and spray flow are investigated. The result shows that the maximum heat flux of evaporator bland plate is 32 W·cm^-2. HPs absorb energy from low grade heat source between 40 to 80℃, and then transfer the energy to the droplets already flashed to keep or even increase the degree of superheat while evaporate. Thus, this method can significantly improve the water separation rate (quality of condensed water/quality of dilute solution ×100%). The initial superheat degree is replaced by temperature of cold source and heat source as the major factor on separating effect. The control of separation rate can be realized through adjusting the parameters. Therefore, this method has important implications for effective utilization of lower grade heat source, gaining brine and promoting the fresh water production unit volume and adaptability to variable load in desalination project.

Key words: evaporation, heat transfer, solution, separation

摘要：

将热管高效传热和高压喷雾技术应用于单级真空蒸发器,对含盐量3%的人造海水进行试验,结果表明:热管吸收40～80℃的低品位热源热量并以高热通量传递给闪蒸后的液滴,能保持甚至提高液滴蒸发过程的过热度,显著增大水分离率;冷热源温度取代初始过热度成为影响分离效果的主要因素,但要避免干壁现象;改变冷热源温度、初始过热度及流量能实现对分离率的调节。该方法对低品位热源在海水淡化工程中的有效利用、提升单位体积装置淡水产量和制取浓盐水均有重要参考价值。

关键词: 蒸发, 传热, 溶液, 分离