The present invention relates to a heat exchanger (2) having a jacket (10) through which a first medium (A) can flow and which has at least one first inlet (11) and at least one first outlet (12), at least one tube (30) through which a second medium (B) can flow, the tube (30) being guided through the jacket (10) and having at least one second inlet (31) and at least one second outlet (32), wherein a deflection segment (50) or a plurality of deflection segments (50) are arranged in a row in a longitudinal axis (X) in the jacket (10), wherein the deflection segment (50) is formed from at least two partial sections (51, 52), which are arranged so as to overlap and cross, in areas, transverse to the longitudinal axis (X).