Low-Flow Liquid Desiccant Air-Conditioning: Demonstrated Performance and Cost Implications

Eric Kozubal, Michael Deru, Andy Lowenstein, Jordan Clark

Research output: NRELTechnical Report


Cooling loads must be dramatically reduced when designing net-zero energy buildings or other highly efficient facilities. Advances in this area have focused primarily on reducing a building's sensible cooling loads by improving the envelope, integrating properly sized daylighting systems, adding exterior solar shading devices, and reducing internal heat gains. As sensible loads decrease,however, latent loads remain relatively constant, and thus become a greater fraction of the overall cooling requirement in highly efficient building designs, particularly in humid climates. This shift toward latent cooling is a challenge for heating, ventilation, and air-conditioning (HVAC) systems. Traditional systems typically dehumidify by first overcooling air below the dew-pointtemperature and then reheating it to an appropriate supply temperature, which requires an excessive amount of energy. Another dehumidification strategy incorporates solid desiccant rotors that remove water from air more efficiently; however, these systems are large and increase fan energy consumption due to the increased airside pressure drop of solid desiccant rotors. A third dehumidificationstrategy involves high flow liquid desiccant systems. These systems require a high maintenance separator to protect the air distribution system from corrosive desiccant droplet carryover and so are more commonly used in industrial applications and rarely in commercial buildings. Both solid desiccant systems and most high-flow liquid desiccant systems (if not internally cooled) add sensibleenergy which must later be removed to the air stream during dehumidification, through the release of sensible heat during the sorption process.
Original languageAmerican English
Number of pages104
StatePublished - 2014

NREL Publication Number

  • NREL/TP-5500-60695


  • dehumidification
  • LDAC
  • liquid desiccant air conditioning
  • net-zero energy


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