Heat exchanger of polymers and composite materials

The invention essentially relates to a heat exchanger (10) for exchanging heat between a first gas flow and a second fluid flow, which comprises parallel plates (2) made of a polymer material and comprising a plurality of longitudinal ducts (22) defining a space (14) intended for the first gas to flow therethrough, and which comprises vanes (16) made of a polymer composite material provided in said horizontal space (14), characterized in that each vane (16) comprises at least one layer of pyrolytic carbon fibers and at least two layers of a polymer material on either side of the layer of the carbon-fiber material, and in that the vanes (16) provided in said space (14) are made of a single piece from an embossed plate (18).