Transient Two-Dimensional (r-z) Cyclic Charging/Discharging Analysis of Space Thermal Energy Storage Systems (RESEARCH NOTE)

Abstract

A two-dimensional transient axi-symmetric model was developed to study the effects of various thermal and geometric parameters on cyclic heating and cooling modes of a phase-change thermal energy storage system. The high-temperature thermal energy storage device utilizes LiH for heat sink applications to store the waste heat generated during power-burst periods. The stored heat is then discharged into space through radiators during the off-peak periods. The enthalpy method is developed to analyze a shell and tube configuration where the phase-change material is contained in an annulus by an inner tube and an outer shell. The development ignores the energy source, pressure variation, and external work done. The Gauss-Seidel iterative method with successive over-relaxation is used to solve the non-linear simultaneous difference equations. The charging period is about 1000 seconds (0.27777 hours). Various effective liquid thermal conductivities have significant effects on heating periods and various inner tube and outer shell radius have significant effects on cooling periods.