Heat exchangers play a important role in the field of energy conservation, conversion, and recovery. Shell and tube heat exchangers are most widely used in many engineering applications for the transfer of heat energy. They are widely adopted in many industries due to their ability to transfer large amounts of heat in relatively low cost, serviceable designs without mixing the hot and old fluids. They can provide large amounts of effective tube surfaces while minimizing the requirements of floor space, liquid volume and weight. For compacting the size of the heat exchangers, the heat transfer coefficient has to be increased. With the rapid development of modern nanotechnology, nanoparticles are used for dispersing in base liquids, which are called as Nano fluids. Nano fluids can be applied to improve the performance of heat exchanger. In this thesis, thermal performance of a shell and tube heat exchanger operated with Nano fluids has been analytically investigated at different volume concentrations and compared with water as the base fluid. Turbulent flow conditions are considered in the analysis. Thermal and CFD analysis is done on the heat exchanger by applying the physical properties of the nanofluid with different volume fractions calculated from the theoretical calculations. 3D model of the heat exchanger is done in CATIA and analysis is done in Ansys fluent. Aluminum and Copper are considered as the materials for tubes in the heat exchanger.