A Liquid-Desiccant Outdoor Air Conditioner for Low-Electricity Humidity Control
EW-200822
Objective
Air conditioning is the single largest contributor to peak demand on electric grids and is the primary cause of grid failure resulting in blackouts. Power generators and electric air conditioners are least efficient at high ambient temperatures when cooling demand is highest, straining regional water resources and leading to increased pollution, excessive investment in standby generation capacity, and poor utilization of peaking assets. Evaporative cooling can help meet Department of Defense energy policy goals by eliminating energy waste and reducing electric demand. However, common experience is that evaporative coolers do not provide sufficient comfort, largely because of their inability to dehumidify and their poor performance during humid weather. Heat-powered dehumidifiers can extend the benefits of evaporative cooling to humid climates. The objective of this project is to demonstrate the capabilities of new high-performance liquid desiccant-dedicated outdoor air technology to enhance cooling efficiency and comfort in wet climates while substantially reducing peak demand on the power grid. This new approach is more efficient and maintainable than traditional "flooded packing" designs. The project will quantify energy and water consumption, as well as cost savings relative to air conditioners.
Technology Description
Low-flow, direct-contact liquid-desiccant technology is a completely new dedicated outdoor air conditioning approach that provides superior dehumidification. One 3,000-cfm unit provides more than 10 tons of latent cooling (approximately 15 gal/hr), freeing up sensible capacity in other air conditioners or chillers and letting them run more efficiently with higher evaporator or chilled water temperatures. The only electrical input to the system runs fans and small pumps resulting in cooling energy efficiency ratios (EER) over 65. EER is the generally accepted metric for comparison of cooling equipment performance. It is the ratio of cooling capacity (Btu/h) to electrical input (kW). As a reference, the current Department of Energy standard for seasonal EER is 13, and its long-term goal is 20. Thermal energy for the liquid-desiccant air conditioner can be recovered from engine gensets, microturbines, turbines, fuel cells, solar collectors, or other processes with recoverable heat between 150°F and 300°F. Dehumidification energy is converted to heat, which can be rejected to a cooling tower, drycooler, or groundwater loop.
Benefits
Peak power demand reductions in excess of 20% are possible with proportionate reductions in demand charges. This is expected to reduce strain on the grid, increase electric delivery reliability, and reduce projected service expansion costs. Air conditioning energy reductions of 25% are expected for liquid-dessicant technology when using solar or recovered waste heat as the primary energy input. (Anticipated Project Completion - 2011)
Points of Contact
Principal Investigator
Mr. Eric Kozubal
National Renewable Energy Lab (NREL)
Phone: 303-384-6155
Fax: 303-384-7540
Document Types
- Fact Sheet - Brief project summary with links to related documents and points of contact.
- Final Report - Comprehensive report for every completed SERDP and ESTCP project that contains all technical results.
- Cost & Performance Report - Overview of ESTCP demonstration activities, results, and conclusions, standardized to facilitate implementation decisions.
- Technical Report - Additional interim reports, laboratory reports, demonstration reports, and technology survey reports.
- Guidance - Instructional information on technical topics such as protocols and user’s guides.
- Workshop Report - Summary of workshop discussion and findings.
- Multimedia - On demand videos, animations, and webcasts highlighting featured initiatives or technologies.
- Model/Software - Computer programs and applications available for download.
- Database - Digitally organized collection of data available to search and access.