Heat exchanger and charging

The invention relates to a heat exchanger (10, 20, 30) for heat exchange between a first fluid (1) on one side, in particular an exhaust gas and / or charge air, and a second fluid (2) on the other hand, in particular a coolant, with a heat exchanger block (11) comprising: - a housing (12) with flow ports (I, II, III) for the second fluid (2) to one of the second fluid (2) through which the housing interior (15), - a heat exchanger core (13) through which to separate and heat-exchanging guidance of the first and second fluids (1, 2), with a number of the first fluid (1) flow channels (14) in the housing interior (15) , said - are arranged, the flow connections (I, II, III) such that in operation - a flow of the second fluid (2) in the housing interior (15) largely parallel to a flow of the first fluid (1) extending main flow (2H) and a largely in a section transverse to the flow of the first fluid (1) extending secondary flow (2N ) having. According to the invention it is provided that (A) passing the main flow (2H) in a direction opposite to the flow of the first fluid (1), or (B) passing the main flow (2H) in a direction of flow of the first fluid (1), and (I) the secondary flow (2N) in the section has an inclined or curved flow path, and / or (Ii) the main flow (2H) with ...