Abstract: The invention relates to a heat-exchanger module with a longitudinal axis (X) comprising at least two fluid circuits, the first of which comprises at least one pair of channels (1, 2) for fluid circulation, each extending parallel to the longitudinal axis (X), wherein the two channels of a single pair are stacked on top of one another and are in communication with one another in a plurality of crossing areas (3) each defining an area for mixing the fluid with itself inside the first circuit.