A team working at the University of Singapore has developed a prototype system that basically uses evaporative cooling, but in a very innovative way. Their process accomplishes the cooling in two separate steps. First, the air is passed over paper filters coated with super hydrophilic chemicals which separate the water vapor from the air. Then, the very dry air passes through a series of counter flow passages, 10 to 20% through wet channels and the remaining through dry channels. Evaporative cooling takes place in the wet channels. Each pass can drop the temperature about 6 degrees. And since humidity and temperature are treated separately, they can be controlled very accurately, basically independent of each other.
Three monumental benefits of this system. First, no harmful chlorofluorocarbons are involved. Second, evaporative cooling replaces costly and energy hog compressors. And third, the system produces drinkable water. In Singapore where the outside humidity is typically 85% (and 50% of the water is imported, 30% recycled), the prototype system produces 12 to 15 liters of water, only 1 liter of which is needed to keep the wet channels wet. The net gain of useful water could have an enormous impact in areas where a lack of clean water causes significant health problems, and at the same time bring indoor cooling to people who have never experienced such an environment.
There will certainly be challenges in scaling up this test system and its application in areas where the humidity is low, however the benefits are so substantial that the power of "Green" takes on a whole new meaning. - Dr. Tom
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