Flight experiment of thermal energy storage

Thermal energy storage (TES), which enables a solar dynamic system to deliver constant electric power through periods of sun and shade, is discussed. Brayton and Stirling power systems under current considerations for missions in the near future require working fluid temperatures in the range from 1100 to above 1300 K range. Tests of the fluoride family of salts which meet these requirements are described. The principal feature of fluorides that must be taken into account is the change in volume that occurs with melting and freezing. Analysis of the transient, two-phase phenomenon, which is being incorporated into a three-dimensional computer code, is discussed. The objective of a planned flight program is to verify the predictions of the code, particularly the void location and its effect on containment temperature. The four experimental packages comprising the program represent the first tests of melting and freezing conducted under microgravity.<>