A study on sensible thermal energy storage (TES) for high temperature solar systems is numerically accomplished. The high temperature TES is cylindrical, the fluid and the solid thermo-physical properties are temperature independent and the radiation heat transfer mechanism is neglected. A parametric analysis is carried out. The commercial CFD Fluent code is used to solve the governing equations in the transient regime. Numerical simulations are carried out at different mass velocity values of the heat-carrying fluid and porosity of the storage medium. The results show the effects of the porosity and of the working fluid mass velocity on the stored thermal energy and on the storage time.