Development of encapsulated lithium hydride thermal energy storage

A packed-bed thermal storage (TES) unit using encapsulated LiH spheres has been proposed as a means of reducing the mass and size of space-based heat rejection systems in applications with pulsed power needs. Assessment of the concept indicated that mass and area savings are possible for applications having power generation periods as long as 1600 s. The major area of technical uncertainty is associated with shell stresses during heating, when the melting (and expanding) LiH at the shell surface is trapped between the encapsulating shell and the solid LiH core. A series of feasibility tests demonstrated that the LiH cracks during cooldown and that the LiH uses these paths to communicate with the central void during charging. The feasibility of the concept was proved conclusively in a reliability demonstration test series, when the 50 mm diameter encapsulated LiH test article completed 50 thermal cycles (twice the application lifetime). The work completed to date indicates that the proposed TES system has merit for pulses space power systems and that the encapsulated-LiH concept is feasible