Evaporative cooling was the brainchild of Ron Judkoff, a Peace Corp volunteer working in Senegal in the 1970s. Judkoff is now the director of Buildings and Thermal Systems at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL).
Judkoff noticed the Sengalese used porous clay pots that allowed evaporation while actively cooling the water within. He made many observations and tucked them away, and years later after much study and experimentation, Judkoff applied these principals to air conditioning.
NREL’s Desiccant-Enhanced Evaporative (DEVAP) system works in any climate and achieves comfortable cooling while saving 40% to 80% of the energy use of a conventional air conditioning system. The DEVAP system has many advantages over traditional air conditioning. DEVAP uses no chlorofluorocarbons, hydrochlorofluorocarbons, or hydrofluorocarbons in vapor compression systems.
In fact, its working fluids are environmentally benign – comprised of only water and a salt solution for the desiccant. Unlike traditional A/C DEVAP offers independent humidity and temperature control. DEVAP is incredibly energy efficient and has very few working parts. The simple design makes the design very cost effective since there is no need for copper coils or a compressor.
Typically, A/C units cool and dehumidify air simultaneously in an uncontrolled way. Water condensation on the evaporator coils dictates the levels of drying. This is called the wet-bulb limit and is the reason most evaporative coolers do not cool the area down efficiently and quickly to create a comfortable space that contains both heat and humidity.
DEVAP cools in any climate by removing the moisture from the air, thereby lowering the effective temperature limit achievable by the indirect evaporative cooler. It has a wet-bulb effectiveness of 125% – huge compared to most current technology that cannot even reach 100%.