This study deals with solidification and melting of some typical encapsulated ice thermal energy storage geometries. Using ANSYS GAMBIT and FLUENT 6.0 software, HTF fluid motion past encapsulated water (ice) geometries, varying HTF flow rates and inlet temperatures are analyzed. The main source of irreversibility was from entropy generation accompanying phase change, although viscous dissipation losses were included. Energy efficiencies were well over 99% for all cases, while exergy efficiencies ranged from 70% to 92%. By far, the most influential variable was the inlet HTF temperature; higher efficiencies resulted from inlet HTF temperatures closer to the solidification temperature of water. / UOIT