BOUZNAD ,Abdelkhalek AmarN. BOULAKTOUT2025-11-302025-11-302025http://dspace.univ-skikda.dz:4000/handle/123456789/5523The aim of this study is to investigate the thermal enhancement performance of stearic acid melting in an annular heat tube exchanger system. The study emphasizes the effect of eccentricity on melting dynamics and heat transfer characteristics. A two-dimensional geometry of three configurations was simulated using ANSYS Fluent and the enthalpy-porosity method: a concentric setup and two eccentric configurations with varying offsets. The results reveal that increased eccentricity significantly enhances natural convection, accelerates the melting process, and improves overall heat transfer efficiency, with an optimal geometric configuration enhancing the melting rate by up to 40.5%. These findings demonstrate the importance of geometric optimization in the design of latent heat thermal energy storage systems in horizontal annular systems.enMémoire de Master