
Zeolites in Solar Energy Applications
Date: Sunday, July 25, 2004 @ 22:23:49 UTC Topic: Devices
Zeolites are in the silicate family of minerals. They have many unique properties, some of which make them attractive for possible use in heating and cooling systems, which use solar energy as a heat source.
When heated, zeolites release water vapor. As long as they stay dry, they can store large amounts of heat for months. When zeolites are allowed to absorb moisture, they release their stored heat. According to some studies, this regenerative cycle can be repeated indefinitely.
Unlike other methods of storing solar heat, such as in water tanks or rock beds, containers for zeolites do not require insulation. Because of the relatively high cost of zeolites, however, zeolite heat storage is not yet available for residential use.
Zeolites have been investigated for use in solar cooling devices. Zeolites are placed inside a solar panel located on top of a condenser, a low-pressure water storage container, and a refrigerator compartment. Sunlight dries the zeolites, which release water vapor. The water vapor is then forced through the condenser to the underlying water storage container where the vapor cools and changes to a liquid. At night, the low pressure in the container causes some water to vaporize and return to the zeolites, bypassing the condenser. The zeolites bond with the water vapor, and release heat that radiates up through the collector and into the sky. The water remaining in the container freezes due to the loss of heat energy, which keeps the refrigerator compartment cold until the next cycle begins.
Bibliography
The following publications and articles provide additional information about zeolites in solar heating and cooling systems.
The Development of a Low Cost Integrated Zeolite Collector, D. Tchernev, U.S. Department of Energy, 1981. 98 pp. Available from the National Technical Information Service (see Source List below). Report Number DE81027660; 1983 supplement, Report Number DE83008484.
Exploration of Molecular-Sieve Zeolites for the Cooling of Buildings with Solar Energy: Final Report, D. Tchernev, Massachusetts Institute of Technology, Lincoln Laboratory, 1977. 99 pp. Available from the National Technical Information Service (see Source List below). Report Number PB-266-055.
Exploration of Molecular-Sieve Zeolites for the Cooling of Buildings with Solar Energy: Semi-Annual Progress Report, D. Tchernev, Massachusetts Institute of Technology, Lincoln Laboratory, 1975. 25 pp. Available from the National Technical Information Service (see Source List below). Report Number TID-26784.
"Natural Zeolites in Solar Energy Heating, Cooling, and Energy Storage," D. Tchernev, Chapter 17, pp. 589-617, of Natural Zeolites: Occurrence, Properties, Applications (Volume 45: Reviews in Mineralogy and Geochemistry), D. Bish and D. Ming, Eds., Mineralogical Society of America (MSA), 2001. 662 pp. ISBN 0-939950-57-X. Available from MSA, Email: business@minsocam.org.
"Overview of Development Programs in Solar Desiccant Cooling For Residential Buildings", B. Shelpuk and D. Hooker, ASHRAE Transactions, (85:2) pp. 749-59, February 1979.
Proceedings of the Desiccant Cooling Conference of November 16, 1977, B. Shelpuk, Solar Energy Research Institute, 1977. 86 pp. Available from the National Technical Information Service (see Source List below). Report Number SERI-22.
"Solar Energy Cooling with Zeolites," D. Tchernev, Proceedings of the Workshop on Solar Collectors for Heating and Cooling of Buildings, New York, NY, November 21, 1974, pp. 262-66. Proceedings available from the National Technical Information Service (see Source List below). 500 pp. Report Number PB-243908.
"Solar Energy Storage Using Chemical Potential Changes Associated with Drying of Zeolites," R. Shigeishi, C. Langford, and B. Hollebone, Solar Energy, (23:6) pp. 489-95, June 1979.
Source List
National Technical Information Service (NTIS)
Email: info@ntis.gov
NTIS adds charges for research, shipping, and handling. Check price and availability before placing an order.
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From: http://www.eere.energy.gov/consumerinfo/factsheets/ba3.html
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