The article presents a numerical investigation of the impact of heat exchanger (HE) location on the performance of the geared turbofan engine (GTF). It discusses the development trend for aero engines, with a primary focus on the modification of the turbofan engine cycle by the addition of the heat exchanger. This paper presents the current state of research on heat exchangers and their application in aero engines. The paper focuses on the thermodynamic model of the GTF engine, with particular emphasis on its modification to study the impact of heat exchangers on engine performance. The assumptions and limitations of the model are also discussed. The study examines the effects of various locations of the heat exchanger in the GTF engine, as well as its efficiency and pressure drop, on the engine overall performance, as measured by thrust and specific fuel consumption (SFC). The study demonstrates that the use of HE has a positive effect on engine thrust, but it also leads to an increase in SFC. According to the results, the HE should be positioned in the core engine of the GTF to achieve maximum thrust. This is achieved when the HE core flow inlet is located at approximately half the pressure ratio of the high-pressure compressor (HPC). It was found that the cold side pressure losses of the HE have a significant impact on engine performance for high bypass ratio turbofan engines. The additional conclusion can be drawn that, when designing a heat exchanger, it is of the utmost importance to take care to minimize its impact on pressure losses in the external channel of the engine.