Seawater desalination using sunlight is a sustainable freshwater production, which contributes the solution of global water shortage. This solar desalination has generally three steps; conversion of solar energy to heat, vaporization of seawater by the heat and condensation of water vapor to form freshwater. We have studied a seawater desalination using two-ply membrane system, where a dye modified hydrophilic membrane is put on a hydrophobic one. When seawater loaded on the system is exposed to sunlight, desalinated water is obtained under the hydrophobic membrane by the membrane permeation of water vapor. This paper reports the improvement of the third step, condensation of water vapor, of our process, which is indispensable for the efficient production of freshwater. When Al petri dish, heatsink and cooling plate were equipped under the two-ply membrane system, the recovery of the vaporized water was remarkably improved by promoting the condensation of water vapor using those devices. Next, capillary action with hydrophilic membrane wick was applied for long term operation of the process with continuous supply of seawater. Finally, a three-ply membrane system, where black light-absorbing sheet, hydrophilic membrane wick and PTFE membrane were stacked, was found to be effective for the mass production of freshwater.

利用阳光进行海水淡化是一种可持续的淡水生产，有助于解决全球缺水问题。这种太阳能脱盐通常分为三个步骤；太阳能转化为热，通过热量蒸发使海水蒸发，以及水蒸气冷凝形成淡水。我们已经研究了使用两层膜系统进行海水淡化的方法，其中将染料改性的亲水膜放在疏水膜上。当负载在系统上的海水暴露在阳光下时，通过水蒸气的膜渗透在疏水膜下获得了脱盐水。本文报告了我们工艺第三步的改进，即水蒸气冷凝，这对于有效生产淡水是必不可少的。当培养皿，散热器和冷却板安装在两层膜系统下，通过使用这些装置促进水蒸气的冷凝，汽化水的回收率得到了显着提高。接下来，在连续供应海水的情况下，采用亲水性膜芯的毛细管作用可长期运行该工艺。最后，发现三层膜系统可以有效地大量生产淡水，该系统中将黑色吸光片，亲水膜芯和PTFE膜堆叠在一起。