A tube bundle heat exchanger with a pipe manifold plate (700, 800), an exchanger flange, a connection curve or a connection fitting and a device for influencing the flow in the area of the pipe manifold plate (700, 800), which has at least one displacement body influencing the flow in the inflow area of the pipe manifold plate (700, 800), wherein the tube bundle heat exchanger has an outer channel (200*) surrounded by an outer sheath for a heat exchange medium, a number of inner pipes each supported in the ends in the pipe manifold (700, 800) together forming an inner channel (300*) extending though the outer channel (200*) axis-parallel to the outer sheath, an inlet or outlet designed in the exchanger flange common for all inner pipes, and a common outlet or respectively inlet for a product implemented in a connection piece, wherein the displacement body is immovably fastened on the connection curve / connection fitting connecting to the exchanger flange or the connection piece, is arranged axially symmetric and concentric to the pipe manifold plate (700, 800), and is comprised of at least two sections (10a, 10b), which together at the connection cross-section thereof form a common largest inner external diameter (d max), wherein the displacement body axially-symmetrically divides the flow to the inner channel (300*), diverts the flow outwards and in doing so accelerates the flow in a nozzle-like narrowed annular gap cross-section (A s), wherein the latter is formed between the displacement body and an inner contour (K i), corresponding thereto, of the surroundings (500 or 800d) concentrically enclosing the displacement body, formed in the exchanger flange or in the connection piece, and wherein the displacement body, seen in the flow direction, subsequently, together with the inner contour (K i) forms an expanded annular gap cross-section (A SE), characterized in that, • a rotationally symmetric, sleeve-shaped guide ring is arranged concentrically between the displacement body and the exchanger flange or the connection piece, • which with the radially inside inner contour thereof forms an inner inner contour (k i1) which forms the inner contour (K ¡) of the surrounding enclosing the displacement body, • that the guide ring is securely connected directly or indirectly to the connection curve or the connection fitting, • that the guide ring is comprised of at least one inflow section and an outflow section, which at their connection cross-section together form a common, largest outer external diameter (D max), • that the guide ring divides the flow axially symmetrically to the inner channel (300*), diverts the flow outwards, and in doing so accelerates the flow in a nozzle-like narrowed outer annular gap cross-section (A S2) between the guide ring and an outer inner contour (K i2) of the exchanger flange or the connection piece, • and that the guide ring, as seen in the flow direction, subsequently together with the outer inner contour (K i2) forms an expanding outer annular gap cross-section (A SE2). • a rotationally symmetric, sleeve-shaped guide ring is arranged concentrically between the displacement body and the exchanger flange or the connection piece, • which with the radially inside inner contour thereof forms an inner inner contour (k i1) which forms the inner contour (K ¡) of the surrounding enclosing the displacement body, • that the guide ring is securely connected directly or indirectly to the connection curve or the connection fitting, • that the guide ring is comprised of at least one inflow section and an outflow section, which at their connection cross-section together form a common, largest outer external diameter (D max), • that the guide ring divides the flow axially symmetrically to the inner channel (300*), diverts the flow outwards, and in doing so accelerates the flow in a nozzle-like narrowed outer annular gap cross-section (A S2) between the guide ring and an outer inner contour (K i2) of the exchanger flange or the connection piece, • and that the guide ring, as seen in the flow direction, subsequently together with the outer inner contour (K i2) forms an expanding outer annular gap cross-section (A SE2).