Evaluation of Eutectic Fluoride Thermal Energy Storage Unit Compatibility. Part I. Survey of Thermophysical Property Data and Description of Clad/Salt Sample Preparation.

摘要

The University of Dayton is conducting an evaluation of thermal energy storage units suitable for Vuilleumier spacecraft cyrocooler applications. The thermal energy storage units are utilizing the liquid-solid phase transformation of eutectic fluorides for the energy storage mechanism. Thermal energy storage units consisting of eutectic compositions of the LiF-MgF2 system, the LiF-MgF2-NaF system, and the LiF-MgF2-KF system and Inconel 617 alloy containers were fabricated. The results of the analytical techniques, which included differential thermal analysis, X-ray diffraction analysis, scanning electron microprobe analysis, Auger spectrometry, and optical microscopy, which were employed in the evaluation of these units are presented. The values for the heat of fusion and the melting temperature are reviewed for three classes of materials; the elements, the metal oxides, and the metal fluorides. The liquid-solid transformation occurring in binary systems of these three classes of materials are reviewed and candidate systems which have a high potential for improved performance are recommended for further study. (Author)