The invention relates to a heat exchanger comprising a supercritical carbon-dioxide circuit comprising a plurality of tubes (1).The heat exchanger is original in that at least one section of the tubes (1) have surface irregularities (3) on their inner surface. These irregularities (3) are located within a zone (6) extending as far as a point located at a distance from the inlet (7) of the tube of maximum 400 times the diameter of the tube.