An intermediate tube bottom, having insert tubes arranged concentrically in the tubes, is located in the inlet chamber, with these insert tubes projecting out on both sides from the tubes and forming annular spaces therewith. The heat exchanger has an inlet tube bottom and an outlet tube bottom, in which are fastened the ends of tubes which connect the bottoms and through which the medium of high inlet temperature flows.

A tube-bundle heat exchanger for cooling a medium having a high inlet temperature. Toward the inlet chamber, the annular spaces open into an intermediate chamber limited by the inlet tube bottom and the intermediate tube bottom; in the opposite direction, the annular spaces open into a deflecting or reversing chamber sealingly covering the insert tubes.