A heat exchanger is a device used to transfer thermal energy between two or more fluids, at different temperatures in thermal contact. They are widely used in aerospace, chemical industries, power plants, refineries, HVAC refrigeration, and in many industries. The optimal design and efficient operation of the heat exchanger and heat transfer network plays an important role in industry in improving efficiencies and to reduce production cost and energy consumption. In this paper, significance of shape of inner pipe of double pipe heat exchanger was analyzed with respect to triangular, hexagonal and octagonal shaped inner pipes. The performance of double pipe heat exchangers was investigated with and without dent pattern using CFD analysis in ANSYS and efficient heat transfer results are identified from CFD outputs. On basis of literature review, few factors influencing the efficiency of heat exchanger and method to improve the efficiency are discussed.