Thermal Conductivity of FLiNaK in a Molten State

Rudenko, A. V.; Redkin, Alexander; Il’ina, Evgeniya; Першина, С. В.; Mushnikov, Peter; Zaikov, Yu. P.; Kumkov, Sergey S.; Shi, Wei‐Qun

doi:10.3390/ma15165603

Cited by 11 publications

(5 citation statements)

References 30 publications

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“…The first measurements of thermal diffusivity ( D ) for the FLiNaK eutectic were in the 1980s , with the current increased interest resulting in a series of more recent measurements ,,,, (Figure b). Among these, several appear to provide reliable values, with the results from Robertson et al in excellent agreement with the improved ceramic cell results of Kato et al and with those of Rudenko et al, with both latter studies showing a small positive temperature coefficient. Other data sets ,,,, exhibit less coherent results, presenting large positive temperature dependencies which contradicts the existing understanding of the behavior of the related thermal conductivity (κ = D ρ C p ) in molten salts based on molecular dynamics simulations, kinetic theory models, and well-validated and referenced experimental studies. ,,− …”

Section: Resultsmentioning

confidence: 99%

“…Thermal Diffusivity and Thermal Conductivity. The first measurements of thermal diffusivity (D) for the FLiNaK eutectic were in the 1980s 18,105 with the current increased interest resulting in a series of more recent measurements 15,58,59,106,107 (Figure 9b). Among these, several appear to provide reliable values, with the results from Robertson et al 107 in excellent agreement with the improved ceramic cell results of Kato et al 105 and with those of Rudenko et al, 59 with both latter studies showing a small positive temperature coefficient.…”

Section: Densitymentioning

confidence: 99%

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Thermal Property Modeling and Assessment of the Physical Properties of FLiNaK

Schorne-Pinto,

Aziziha,

Tisdale

et al. 2024

ACS Appl. Energy Mater.

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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 [C p (T)] of mixtures, temperature-dependence of mixing enthalpies (Δ mix H), vapor pressures of mixtures, and enthalpies of fusion (ΔH fus ) 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 C p (T) = 69.822 + 0.000679T + 2,137,152T −2 J mol −1 K −1 (732.9 < T < 1200 K) and ΔH fus = 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.

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Section: Resultsmentioning

confidence: 99%

Section: Densitymentioning

confidence: 99%

Thermal Property Modeling and Assessment of the Physical Properties of FLiNaK

Schorne-Pinto,

Aziziha,

Tisdale

et al. 2024

ACS Appl. Energy Mater.

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“…The shape of the cell remained unaltered following the high-temperature experiments. Further details of the precise experimental technique can be found in [8].…”

Section: Laser Flash Methodsmentioning

confidence: 99%

“…Through equilibrium molecular dynamics (MD) calculations, a linear decrease in the λ(T) dependence of FLiNaK thermal conductivity was observed at temperatures of 950 K, 1100 K, and 1250 K [7]. Additionally, Rudenko et al [8] obtained thermal diffusivity using the laser flash method and measured heat capacity through the Differential Scanning Calorimetry (DSC) method, with all these results exhibiting relatively close values. Within the temperature range of 723-873 K, the thermal conductivity value varies from 0.7 to 0.8 W/m K.…”

Section: Introductionmentioning

confidence: 99%

Thermal Properties of NaF–KF and NaF–KF–MgF2 Molten eutectic Mixtures: Experiment and Simulation

Rudenko,

Redkin,

Galashev

et al. 2024

Int J Thermophys

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Molten fluoride salts are under development for use as fuel coolant and thermal storage in industrial nuclear energy production. This study focuses on the experimental and molecular dynamic investigation of thermal conductivity and ion diffusion in the eutectic molten salts of NaF-KF and NaF-KF-MgF2. Experimental and calculated data demonstrate that the temperature-dependent thermal conductivity can be accurately represented as a decaying linear function for both melts. The significant diffusion coefficient of fluorine ions in the NaF-KF molten system can be attributed to the considerable number of Coulomb repulsions among the abundant negative ions in the irregular system. The findings of this study provide insights into the behavior of NaF-KF and NaF-KF-MgF2 molten salt mixtures under operating conditions in high-temperature power plants.

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“…2: Some published data on the thermal conductivity of FLiNaK available in the literature (a) and from the past 10 years (b). In a), data comes from 1952 Deem type [11], 1962 uniaxial [12], 1987 concentric cylinders [13], 2011 concentric cylinders [14], 2015 laser flash analysis (LFA) [15], 2017 bare or non-insulated transient hot wire (THW) [8], 2022 LFA [16], 2022 transient grating spectroscopy (TGS) [10], 2022 guarded variable gap apparatus [7], and 2022 needle probe (NP) [17]. In b), points represent actual measured data while lines represent data from theoretical predictions from some recent papers.…”

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confidence: 99%

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

Ruth,

Merritt,

Munro

2024

Preprint

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This paper considers the necessary conditions for using a derivative of a transient hot wire (termed a needle probe) approach to measure electrically conducting fluids at high temperatures, especially molten halide salts. The focus is on the development of a new theory based on a multi-layer system necessary to ensure electrical isolation of electrical wires from the surrounding fluid. This includes the use of a thin annulus of fluid to minimize convective heat transfer modes within the fluid of interest, which was inspired by the concentric cylinder method. Good measurements require the following considerations: concentricity of the probe and surrounding crucible to ensure a consistent fluid gap, accounting for corrections for deviation of the model at early times, and modeling radiation heat transfer through transparent fluids. Uncertainties are larger than transient hot wire methods because of the deviations from experimental conditions that can easily match an analytical approximation. An appropriate estimation of the measurement uncertainty can be obtained through careful design of the instrumentation, thorough uncertainty analysis, and limiting the measurements to only the applicable thermal property ranges of the approach. The 1D model used to interpret measured temperature data has been shown to be reliable for thermal conductivity measurements ranging from at least 0.39 W/mK to 0.92 W/mK and for temperatures from 293-1023 K. The approach is used to present thermal conductivity data of the molten salts NaCl-KCl (51-49 mol%) and LiCl-NaCl (28-72 mol%).

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Thermal Conductivity of FLiNaK in a Molten State

Cited by 11 publications

References 30 publications

Thermal Property Modeling and Assessment of the Physical Properties of FLiNaK

Thermal Property Modeling and Assessment of the Physical Properties of FLiNaK

Thermal Properties of NaF–KF and NaF–KF–MgF2 Molten eutectic Mixtures: Experiment and Simulation

Use of a Needle Probe to Measure the Thermal Conductivity of Electrically Conductive Liquids at High Temperatures

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