Thermal Property Modeling and Assessment of the Physical Properties of FLiNaK

Juliano Schorne-Pinto, Mina Aziziha, Hunter B. Tisdale, Amir M. Mofrad, Anthony Birri, Matthew S. Christian, Johnathon C. Ard, Ronald E. Booth, Jacob A. Yingling, Jorge Paz Soldan Palma, Clara Dixon, Hans Conrad zur Loye, Theodore M. Besmann

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

The thermodynamic properties of the LiF-NaF-KF system and its subsystems were re-evaluated using the CALPHAD method, focusing on the deviations from ideality in the heat capacity [Cp(T)] of mixtures, temperature-dependence of mixing enthalpies (ΔmixH), vapor pressures of mixtures, and enthalpies of fusion (ΔHfus) using reported values and measurements. The results of this work confirmed a pseudoternary eutectic at 732.9 K and 46.5LiF-11.5NaF-42KF mol % (FLiNaK) with determined Cp(T) = 69.822 + 0.000679T + 2,137,152T-2 J mol-1 K-1 (732.9 < T < 1200 K) and ΔHfus = 18,051 J mol-1 in good agreement to the experimental values. The resulting accurate thermodynamic representation can be used to find relevant excess thermochemical properties in the whole pseudoternary space and provide insights into their composition and temperature dependence. A detailed evaluation of select thermophysical properties was also conducted to determine recommended density, thermal diffusivity, thermal conductivity, vapor pressures, and boiling point with calculated uncertainties over the temperature range of interest for FLiNaK-salt energy applications.

Original languageEnglish
Pages (from-to)4016-4029
Number of pages14
JournalACS Applied Energy Materials
Volume7
Issue number9
Early online dateMay 13 2024
DOIs
StatePublished - May 13 2024
Externally publishedYes

Keywords

  • boiling point
  • enthalpy of fusion
  • FLiNaK
  • heat capacity
  • molten salts
  • phase diagrams
  • thermal conductivity
  • vapor pressure

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