Hydrogen permeability through a mixed molten salt of LiF, NaF and KF (Flinak) as a heat-transfer fluid

Permeability, diffusivity and solubility of hydrogen in Flinak, a mixed molten salt of LiF (46.5%), NaF (11.5%) and KF (42%), were determined using a vessel supported by a Ni plate. Diffusion-limiting permeation was confirmed by experimental data where hydrogen permeation rates were in reverse proportion to the thickness of Flinak. Diffusivities determined in the range of 500-750 degrees C were correlated to an Arrhenius equation with the activation energy of 50 kJ/mol. Since the dependence of hydrogen solubility in Flinak on pressure was almost linear, hydrogen was dissolved as H-2 in Flinak. The H-2 solubility in Flinak was correlated to a Henry law, and its solubility constant was discussed in terms of macroscopic surface tension and unspecified interaction energy between the molten salt and dissolved gaseous molecules. (c) 2006 Elsevier B.V. All rights reserved.