The master thesis deals with thermal hydraulic design and strength design of a heat exchanger with “U” tube bundle inside of a shell. The first chapter introduces general design issues of the heat exchangers. The following chapter describes thermal hydraulic design created in software Maple 16.0 by using Kern’s method and the method of Bell-Delaware. HTRI software was used for the control of thermal hydraulic design correctness. To check critical locations of fluid flow in space between the tubes, the CFD model was created at ANSYS Fluent 14.0 software. Accuracy of strength design was verifying by Sant’ Ambrogio software in accordance with ČSN EN 13 445 standards. The last chapter concerns with FEM analysis. According to standards ČSN EN 13 445 the design by analysis namely method based on stress categories were used for the strength analysis of nozzle.