Zero Carryover Liquid-Desiccant Air Conditioner for Solar Applications: Paper No. ISEC2006-99079

Andrew Lowenstein, Steven Slayzak, Eric Kozubal

Research output: Contribution to conferencePaperpeer-review

30 Scopus Citations

Abstract

A novel liquid-desiccant air conditioner that dries and cools building supply air has been successfully designed, built and tested. The new air conditioner will transform the use of direct-contact liquid-desiccant systems in HVAC applications, improving comfort and indoor air quality, as well as providing energy-efficient humidity control Liquid-desiccant conditioners and regenerators are traditionally implemented as adiabatic beds of contact media that are highly flooded with desiccant. The possibility of droplet carryover into the supply air has limited the sale of these systems in most HVAC applications. The characteristic of the new conditioner and regenerator that distinguishes them from conventional ones is their very low flows of liquid desiccant. Whereas a conventional conditioner operates typically at between 10 and 15 gpm (630 and 946 ml/s) of desiccant per 1000 cfm (0.47 m3/s) of process air, the new conditioner operates at 0.5 gpm (32 ml/s) per 1000 cfm (0.47 m3/s). At these low flooding rates, the supply air will not entrain droplets of liquid desiccant. This brings performance and maintenance for the new liquid-desiccant technology in line with HVAC market expectations. Low flooding rates are practical only if the liquid desiccant is continually cooled in the conditioner or continually heated in the regenerator as the mass exchange of water occurs. This simultaneous heat and mass exchange is accomplished by using the walls of a parallel-plate plastic heat exchanger as the air/desiccant contact surface. Compared to existing solid and liquid desiccant systems, the low-flow technology is more compact, has significantly lower pressure drops and does not "dump" heat back onto the building's central air conditioner. Tests confirm the high sensible and latent effectiveness of the conditioner, the high COP of the regenerator, and the operation of both components without carryover.

Original languageAmerican English
Pages397-407
Number of pages11
DOIs
StatePublished - 2006
Event2006 International Solar Energy Conference, ISEC2006 - Denver, CO, United States
Duration: 8 Jul 200613 Jul 2006

Conference

Conference2006 International Solar Energy Conference, ISEC2006
Country/TerritoryUnited States
CityDenver, CO
Period8/07/0613/07/06

Bibliographical note

For preprint version see NREL/CP-550-39798

NREL Publication Number

  • NREL/CP-550-40512

Keywords

  • Air conditioner
  • Dehumidifier
  • HVAC
  • Liquid desiccant

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