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Molten Salt Heat Transfer Fluid (HTF)

Sandia National Laboratories

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PDF Document PublicationMarket Sheet (739 KB)

Sandia's National Solar Thermal Test Facility
Sandia's National Solar Thermal Test Facility

Technology Marketing Summary

Sandia has developed a heat transfer fluid (HTF) for use at elevated temperatures that has a lower freezing point than any molten salt mixture available commercially. This allows the HTF to be used in applications in which the expensive parasitic energy costs necessary for freeze protection can be significantly reduced. The higher operating temperature limit significantly increases power cycle efficiency and overall power plan sun-to-net electric efficiency.


One of the primary applications is dual use of this HTF both in parabolic trough solar fields as well as the thermal storage media in the integral thermal energy storage systems. There are many other industries that might also benefit from the development of this molten salt mixture, including those whose processes involve heat treating of metals.

  • Better high-temperature stability than currently available salts
  • Relatively benign in terms of environmental impact
  • Higher density and heat capacity
  • Molten salts are significantly less costly than the oil-based HTF currently used
  • Has virtually no inherent vapor pressure, allowing for use in thermal energy storage tanks
Applications and Industries
  • Solar thermal power plant
  • Energy storage
  • Chemical synthesis
  • Plastics and textiles manufacturing
  • Food processing
  • Paint production
Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 7,588,694
Low-melting point inorganic nitrate salt heat transfer fluid
A low-melting point, heat transfer fluid made of a mixture of four inorganic nitrate salts: 9-18 wt % NaNO.sub.3, 40-52 wt % KNO.sub.3, 13-21 wt % LiNO.sub.3, and 20-27 wt % Ca(NO.sub.3).sub.2. These compositions can have liquidus temperatures less than 100 C; thermal stability limits greater than 500 C; and viscosity in the range of 5-6 cP at 300 C; and 2-3 cP at 400 C.
Sandia National Laboratories 09/15/2009
Technology Status
Technology IDDevelopment StageAvailabilityPublishedLast Updated
SD#10676Prototype - Sandia estimates this technology's readiness level at a level 5. Key elements of the technology have been demonstrated in relevant environments. Available - Various licensing and partnering options are available. Please contact the IP department to discuss. 01/03/201103/12/2013

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