A heat exchanger between a first (N 2) and a second (Na) fluid, comprising: - a sealed enclosure having a central axis and comprising, at one of its longitudinal ends, at least one inlet and one outlet for the first fluid and, at the other of its longitudinal ends, at least one inlet and one outlet for the second fluid, the sealed enclosure being adapted to be pressurized, - at least one heat exchanger module (3.1 to 3.8) incorporating a first and a second fluid circuit, extending parallel to the central axis and arranged inside the enclosure, - a structure (4, 40) for supporting and holding the at least one exchanger module, rigidly fixed to the enclosure, - an inlet or outlet chamber for the first fluid, formed axially between the support and the enclosure, and communicating with one of the inlet and the outlet of the first fluid circuit, - a first central manifold extending around the central axis, arranged axially opposite the chamber and communicating, on the one hand, with one of the inlet and the outlet for the first fluid of the enclosure and, on the other hand, with the other of the inlet and the outlet of the first fluid circuit, - an annular manifold arranged around the first central manifold and the at least one exchanger module at least to the support (4, 40), forming a guiding space for the first fluid and communicating, on the one hand, with the other of the inlet and the outlet for the first fluid of the enclosure and, on the other hand, with the chamber, - at least one inlet conduit (8, 81 to 88) communicating on the one hand with the inlet for the second fluid of the enclosure, and, on the other hand, with an inlet (31 to 38) of the second fluid circuit, - at least one outlet conduit (9, 91 to 98) communicating on the one hand with the outlet for the second fluid of the enclosure, and, on the other hand, with an outlet of the second fluid circuit, the conduits (8, 81 to 88; 9, 91 to 98) not being supported by the support and holding structure. - a sealed enclosure having a central axis and comprising, at one of its longitudinal ends, at least one inlet and one outlet for the first fluid and, at the other of its longitudinal ends, at least one inlet and one outlet for the second fluid, the sealed enclosure being adapted to be pressurized, - at least one heat exchanger module (3.1 to 3.8) incorporating a first and a second fluid circuit, extending parallel to the central axis and arranged inside the enclosure, - a structure (4, 40) for supporting and holding the at least one exchanger module, rigidly fixed to the enclosure, - an inlet or outlet chamber for the first fluid, formed axially between the support and the enclosure, and communicating with one of the inlet and the outlet of the first fluid circuit, - a first central manifold extending around the central axis, arranged axially opposite the chamber and communicating, on the one hand, with one of the inlet and the outlet for the first fluid of the enclosure and, on the other hand, with the other of the inlet and the outlet of the first fluid circuit, - an annular manifold arranged around the first central manifold and the at least one exchanger module at least to the support (4, 40), forming a guiding space for the first fluid and communicating, on the one hand, with the other of the inlet and the outlet for the first fluid of the enclosure and, on the other hand, with the chamber, - at least one inlet conduit (8, 81 to 88) communicating on the one hand with the inlet for the second fluid of the enclosure, and, on the other hand, with an inlet (31 to 38) of the second fluid circuit, - at least one outlet conduit (9, 91 to 98) communicating on the one hand with the outlet for the second fluid of the enclosure, and, on the other hand, with an outlet of the second fluid circuit, the conduits (8, 81 to 88; 9, 91 to 98) not being supported by the support and holding structure.