The task of this thesis is the calculation of the heat exchange in the double tube heat exchanger for the purpose of analyzing the influence of fluid flow direction on heat exchange. Recuperators are heat exchangers where the fluids are separated by a solid and impermeable wall trough which heat is exchanged. Heat is exchanged by convection on the side of the warmer and colder fluid with the wall surface and conduction through the solid wall. The second chapter describes the main laws of heat exchange and classification of basic forms of heat exchange. The third chapter describes heat exchangers and their basic division into recuperators, regenerators and direct heat exchangers. Recuperators, due to their importance, are elaborated in more details in this paper. As a result of the entire work, calculation was carried out according to the given geometry characteristics and input data. The purpose of the calculation is the analysis of the influence of parallel and counter fluid flow direction, on the exchanged heat flux, heat effectiveness and other characteristic physical values. In the fifth chapter, the analysis and comparison of the obtained data was carried out and the same was presented graphically. Concluding on the calculation, the counter-flow heat exchanger is more favorable because for the same heat exchange surface, a larger heat flux is exchanged inside heat exchanger and more heat is used.