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Northward market extension for passive solar water heaters by using pipe freeze protection with freeze-tolerant piping : preprint / J. Burch [and others].
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- Book
- Government document
- Series:
- Conference paper (National Renewable Energy Laboratory (U.S.)) ; NREL/CP-550-39664.
- NREL/CP ; 550-39664
- Language:
- English
- Subjects (All):
- Solar water heaters--Reliability.
- Solar water heaters.
- Pipe freezing (Pipeline maintenance)--Reliability.
- Pipe freezing (Pipeline maintenance).
- Physical Description:
- 1 online resource (6 pages)
- Place of Publication:
- Golden, CO : National Renewable Energy Laboratory, 2006.
- Summary:
- Combining a freeze protection method with fail-safe, freeze-tolerant cross-linked polyethylene (PEX) piping may provide a means to significantly extend the market northward for passive solar water heaters. Stress-strain data on PEX piping materials indicate that the 3.5% hoop strain from uniform freezing is likely tolerable for many cycles, but data are not definitive because it is not clear where permanent deformation starts occurring. Four PEX piping systems were freeze-thaw-cycled ~450 times. One brand showed no freeze tolerance, whereas two other brands appear freeze-tolerant, with no bursts in lengths greater than 7" or less than 2". Two geometries were identified that promote nonuniform freezing and that should be avoided: 1) nonuniform insulation increasing from ends toward the middle of the pipe in longer sections; and 2) pipes of ~4" in length with metal connectors on both ends. All metallic fittings have survived, but several polymer fittings broke and should be avoided when freeze-tolerance is desired. Further testing and analysis is needed to better understand the length dependence of freeze bursting and effects of piping aging, and field testing should proceed cautiously
- Notes:
- Title from title screen (viewed on August 24, 2007).
- "May 2006."
- "To be presented at Solar 2006, Denver, Colorado, July 8-13, 2006."
- OCLC:
- 166295179
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