A typical direct-exchange air conditioner cools the air and dehumidifies it all at once, but not in a controlled way. The limit to how much drying can be achieved is dependent on how much water condenses on the evaporator coils as the air passes through.
The wet-bulb limit is the reason typical evaporative coolers either can’t cool things down enough or can’t create a truly comfortable space when there is a lot of heat and humidity in the air.
By contrast, DEVAP can provide cooling in any climate. The first stage wrings out all the moisture in the air. In doing so, it lowers the effective temperature limit by which the indirect evaporative cooler can achieve. It has a wet-bulb effectiveness of 125 percent — a huge boon compared to most current technology that has tried to get as close as it can to 100 percent.
The other huge advantage of DEVAP is that it is an energy miser. A direct-exchange air-conditioner uses 25 percent of its energy removing humidity and 75 percent dropping the temperature. By contrast, DEVAP only uses energy for that first step, removing humidity. The second step is achieved simply by adding a little water.
“As a cooling process, evaporative cooling is incredibly efficient,” Judkoff said. “The fact that we have to put a little energy into drying the air is more than made up for out of the efficiency of evaporative cooling. Especially compared to typical A/C where you have to use electricity to compress the working fluid.
“Developing a brand new thermodynamic cycle and an apparatus to accomplish this process was difficult.” Kozubal said. Conceptualizing this new device required a lot of ingenuity and breakthroughs in materials to become a reality. It took a lot of pondering. I spent a lot of time looking up at the ceiling.”
Originally published in Innovation: America's Journal of Technology Commercialization. Reprinted with permission.
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