In order to gain an understanding of the mechanism of thermal performance increase in the shell side, a shell and tube heat exchanger is proposed in this study. Numerical investigations of the shell side fluid flow and heat transfer are performed using CFD Fluent software based on the model. The profiles and axial velocity fields, as well as the profiles and temperature distribution at the heat exchanger level were obtained for the whole geometry. The speed increases by 12 % of the reference speed in the shell.