The objective of this study is to analyze the behavior of an energy storage system which is made of a horizontal channel crossed by a fluid and whose walls contain an unsaturated porous medium.We developed a threedimensional model to study the two processes: thermal energy charging and USB Port Connector thermal energy discharging.The coupled and highly non linear nature of the transport equations that govern the heat and mass transfer inside unsaturated medium were discretized by control volume finite element method (CVFEM).The resulted system of algebraic Engine equations was solved by the Bi-Conjugate Gradient Stabilized iterative solver.Results concerning the influence of the initial liquid saturation on the rate of charged and discharged thermal energy are presented and analyzed.