The optimization of shell-and-tube heat exchangers from an economic viewpoint gains in importance because of the current and future share of the market of this heat exchanger type in various industries. The developed computer-based design concept assuming from the calculation of optimum tubeside and shellside pressure drops allows to determine the optimum dimensions of segmentally baffled shell-and-tube heat exchangers. As the objective function that is minimized are chosen the total annual costs of the heating or cooling system consisting of the heat exchanger and pumps or compressors. The discussed design method can be used for single-phase liquid or gaseous stream applications.