skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Temperature-dependent mechanical property testing of nitrate thermal storage salts.

Abstract

Three salt compositions for potential use in trough-based solar collectors were tested to determine their mechanical properties as a function of temperature. The mechanical properties determined were unconfined compressive strength, Young's modulus, Poisson's ratio, and indirect tensile strength. Seventeen uniaxial compression and indirect tension tests were completed. It was found that as test temperature increases, unconfined compressive strength and Young's modulus decreased for all salt types. Empirical relationships were developed quantifying the aforementioned behaviors. Poisson's ratio tends to increase with increasing temperature except for one salt type where there is no obvious trend. The variability in measured indirect tensile strength is large, but not atypical for this index test. The average tensile strength for all salt types tested is substantially higher than the upper range of tensile strengths for naturally occurring rock salts. Interest in raising the operating temperature of concentrating solar technologies and the incorporation of thermal storage has motivated studies on the implementation of molten salt as the system working fluid. Recently, salt has been considered for use in trough-based solar collectors and has been shown to offer a reduction in levelized cost of energy as well as increasing availability (Kearney et al., 2003). Concerns regarding the usemore » of molten salt are often related to issues with salt solidification and recovery from freeze events. Differences among salts used for convective heat transfer and storage are typically designated by a comparison of thermal properties. However, the potential for a freeze event necessitates an understanding of salt mechanical properties in order to characterize and mitigate possible detrimental effects. This includes stress imparted by the expanding salt. Samples of solar salt, HITEC salt (Coastal Chemical Co.), and a low melting point quaternary salt were cast for characterization tests to determine unconfined compressive strength, indirect tensile strength, coefficient of thermal expansion (CTE), Young's modulus, and Poisson's ratio. Experiments were conducted at multiple temperatures below the melting point to determine temperature dependence.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Sandia National Laboratories
Sponsoring Org.:
USDOE
OSTI Identifier:
991535
Report Number(s):
SAND2010-6013
TRN: US201021%%278
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 25 ENERGY STORAGE; AVAILABILITY; COMPRESSION; HEAT STORAGE; HEAT TRANSFER; IMPLEMENTATION; MECHANICAL PROPERTIES; MELTING POINTS; MOLTEN SALTS; NITRATES; SALT DEPOSITS; SOLAR COLLECTORS; SOLIDIFICATION; STORAGE; TEMPERATURE DEPENDENCE; TENSILE PROPERTIES; TESTING; THERMAL EXPANSION; THERMODYNAMIC PROPERTIES; WORKING FLUIDS; Rock salt-Thermomechanical properties.

Citation Formats

Everett, Randy L., Iverson, Brian D., Broome, Scott Thomas, Siegel, Nathan Phillip, and Bronowski, David R. Temperature-dependent mechanical property testing of nitrate thermal storage salts.. United States: N. p., 2010. Web. doi:10.2172/991535.
Everett, Randy L., Iverson, Brian D., Broome, Scott Thomas, Siegel, Nathan Phillip, & Bronowski, David R. Temperature-dependent mechanical property testing of nitrate thermal storage salts.. United States. doi:10.2172/991535.
Everett, Randy L., Iverson, Brian D., Broome, Scott Thomas, Siegel, Nathan Phillip, and Bronowski, David R. Wed . "Temperature-dependent mechanical property testing of nitrate thermal storage salts.". United States. doi:10.2172/991535. https://www.osti.gov/servlets/purl/991535.
@article{osti_991535,
title = {Temperature-dependent mechanical property testing of nitrate thermal storage salts.},
author = {Everett, Randy L. and Iverson, Brian D. and Broome, Scott Thomas and Siegel, Nathan Phillip and Bronowski, David R.},
abstractNote = {Three salt compositions for potential use in trough-based solar collectors were tested to determine their mechanical properties as a function of temperature. The mechanical properties determined were unconfined compressive strength, Young's modulus, Poisson's ratio, and indirect tensile strength. Seventeen uniaxial compression and indirect tension tests were completed. It was found that as test temperature increases, unconfined compressive strength and Young's modulus decreased for all salt types. Empirical relationships were developed quantifying the aforementioned behaviors. Poisson's ratio tends to increase with increasing temperature except for one salt type where there is no obvious trend. The variability in measured indirect tensile strength is large, but not atypical for this index test. The average tensile strength for all salt types tested is substantially higher than the upper range of tensile strengths for naturally occurring rock salts. Interest in raising the operating temperature of concentrating solar technologies and the incorporation of thermal storage has motivated studies on the implementation of molten salt as the system working fluid. Recently, salt has been considered for use in trough-based solar collectors and has been shown to offer a reduction in levelized cost of energy as well as increasing availability (Kearney et al., 2003). Concerns regarding the use of molten salt are often related to issues with salt solidification and recovery from freeze events. Differences among salts used for convective heat transfer and storage are typically designated by a comparison of thermal properties. However, the potential for a freeze event necessitates an understanding of salt mechanical properties in order to characterize and mitigate possible detrimental effects. This includes stress imparted by the expanding salt. Samples of solar salt, HITEC salt (Coastal Chemical Co.), and a low melting point quaternary salt were cast for characterization tests to determine unconfined compressive strength, indirect tensile strength, coefficient of thermal expansion (CTE), Young's modulus, and Poisson's ratio. Experiments were conducted at multiple temperatures below the melting point to determine temperature dependence.},
doi = {10.2172/991535},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Sep 01 00:00:00 EDT 2010},
month = {Wed Sep 01 00:00:00 EDT 2010}
}

Technical Report:

Save / Share: