Different Methods are used to enhance heat transfer in shell and tube heat exchanger. The present work examines numerically the effect of splitting the internal tubes for a shell and tubes heat exchanger on its hydrothermal performance. The effect of the spacing between the semi-circular tubes (SCTs) to the tube diameter; spacing ratio () in addition to the shell-side fluid inlet temperature and flow rate are the main parameters. ANSYS 15 with 3D fluid flow is used for the modelling and simulation of the present study. The Results indicate that splitting the internal tubes of a shell and tube heat exchanger significantly increases the rate of heat transfer and flow resistance in the shellside when compared with that in the heat exchangers of circular tubes. In addition, the shell-side average Nusselt number, friction factor and hydrothermal performance index (HTPI) increase with increasing the SCTs spacing ratio. Finally, the shell and SCTs heat exchanger of  = 0.5 have the highest HTPI; 1.87 at the higher shell-side flow rate.