In this study, a 2D transient numerical model is developed to investigate the performance of a dual media tank (DMT) thermal energy storage (TES) system. The physical model consists of sandstone as storage materials and Syntherm 1000 as an HTF. The model is simulated, and the effect of design and operating parameters on charging rate, pressure drop, and thermocline thickness is studied. The design and operating parameters include void fraction, pebbles diameter, and mass flow rate. The result shows an increase in temperature degradation with a decrease in void fraction. Similarly, the effect of mass flow rate on thermocline thickness is studied, and the result shows 11% drop in thermocline thickness with a 35% increase in mass flow rate. The analysis results indicate that there is a need to optimize the system for optimal design and operating parameters for maximum charging efficiency and minimum pressure drop.