United Technologies Research Center (UTRC)

In hot and humid climates, air conditioners are less efficient because they require more energy to remove water from the moisture-rich air. More efficient cooling methods are necessary to reduce building energy consumption and environmental impact. Buildings currently account for 72% of the nation's electricity use and 40% of our carbon dioxide (CO2) emissions each year, 5% of which comes directly from air conditioning. The refrigerants typically used in air conditioners are potent greenhouse gases (GHG) that may contribute to global climate change. Because the majority of cooling systems run on electricity, and most U.S. electricity comes from coal-fired power plants which produce CO2, there is a pressing need to support improvements that increase the efficiency of these technologies and reduce the use of GHG refrigerants.

United Technologies Research Center (UTRC) is developing an air conditioning system that is optimized for use in warm and humid climates. UTRC's air conditioning system integrates a liquid drying agent or desiccant and a traditional vapor compression system found in 90% of air conditioners. The drying agent reduces the humidity in the air before it is cooled, using less energy. The technology uses a membrane as a barrier between the air and the liquid salt stream allowing only water vapor to pass through and not the salt molecules. This solves an inherent problem with traditional liquid desiccant systems—carryover of the liquid drying agent into the conditioned air stream—which eliminates corrosion and health issues.

If successful, UTRC's air conditioning system would be 50% more efficient than conventional air conditioning units.