ZAHRA RAZZAGHPANAH. Optimization of Thermal Energy Storage Systems integrated with concentrated solar power plants. (Under the direction of DR. NENAD SARUNAC)Concentrated Solar Power (CSP) plants have been a major area of study for many years as an alternative to the conventional methods of power generation. High dependency of the global economy on fossil fuels rises sustainability concerns. Also, global climate change linked to the CO2 emissions from burning fossil fuels, makes it very important to develop and deploy the carbon-free technologies, such as solar energy as a source of power. Utilizing reliable and renewable sources of energy in an economically sound and dependable way is perhaps one of the most important global challenges of the present time. Solar energy, being inexhaustible and non-polluting in contrast to fossil fuels, has gained popularity among scientists and engineers around the world as a potential alternative. However, solar energy is variable and intermittent. Also, the peaks in solar irradiation and electricity demand typically do not coincide, resulting in a need for energy storage. Therefore, to utilize the solar energy most effectively, Thermal Energy Storage (TES) systems are needed for a steady and uninterrupted supply of energy. A two-dimensional (2-D) steady-state numerical analysis of the sensible heat indirect TES comprising a heat exchanger immersed in the heat storage medium was performed to improve understanding of the thermal energy storage process, develop a better design of the high-efficiency TES, and improve utilization of solar energy by reducing its variability during the daytime and allowing its use during the periods of low or no solar irradiation. The statistical regression analysis was used to correlate the results.This project focused on determining the optimum geometry of the heat exchanger(s) used in TES. Numerical simulations were performed for different geometries of the heat exchanger to determine the most efficient design and develop design criteria. Numerical modeling and design analysis of the TES system was performed by employing ANSYS-Workbench and StarCCM+ Professional software packages.