MADANI Mohamed Abd El GhafourLOURMIL SouheylaBENZENINE Hamidou2026-09-132026-09-132026https://dspace.univ-temouchent.edu.dz/handle/123456789/7559This work presents a thermal and numerical study of a double-tube heat exchanger equipped with longitudinal fins mounted on the outer surface of the inner tube using ANSYS Fluent software. The main objective of this study is to analyze the influence of flow rate, hybrid nanofluid type, and nanoparticle volume concentration on the thermal performance of the heat exchanger. The longitudinal fins were used to increase the heat exchange surface area and enhance heat transfer efficiency. After creating the geometry, mesh, and boundary conditions, several numerical simulations were carried out to evaluate the thermal behavior of the fluids and the evolution of outlet temperatures. The obtained results show that the variation of flow rate, hybrid nanofluid type, and concentration directly affects heat transfer efficiency and outlet temperatures. This study highlights the importance of numerical simulation in the analysis and optimization of heat exchangers.frHeat exchangerdouble tubelongitudinal finshybrid nanofluidvolume concentrationheat transfernumerical simulation.Thesis