Device enabling the exchange of heat between at least one first and one second fluid, said device including: - an outer casing sealed against the first and second fluids, - at least one partition wall enabling the exchange of heat between the first and second fluids, said wall being housed inside said outer casing, - a first inlet opening, for the first fluid, formed at a first end of the outer casing, - a second inlet opening, for the second fluid, formed at a second end of the outer casing, opposite the first end of said casing, - said outer casing having a long shape extending between its first and second ends, - said exchange wall extending between said first and second fluid inlet openings, - a first outlet opening, for extracting the first fluid from the outer casing, - a second outlet opening, for extracting the second fluid from the outer casing, - a first pipe enabling the first fluid to flow inside the outer casing between the first inlet opening and the first outlet opening of said first fluid, part of the wall of said pipe being made up by a first face of said exchange wall, - a second pipe enabling the second fluid to flow inside the outer casing between the second inlet opening and the second outlet opening of said second fluid, part of the wall of said pipe being up by a second face of said exchange wall opposite the first face, - said first and said second fluids being intended to flow in a counter-current manner on both sides of the exchange wall, characterised in that: - said first outlet opening, for the first fluid, is formed in the region of said first end of the outer casing, - said second outlet opening, for the second fluid, is formed in the region of said second end of the outer casing, - in such a manner that said second outlet opening for the second fluid, and said first inlet opening, for the first fluid, are separated by a distance equal to or greater than the length (λ) of the exchange wall, and - in such a manner that said first outlet opening for the first fluid, and said second inlet opening, for the second fluid, are separated by a distance equal to or greater than the length (λ) of the exchange wall. - an outer casing sealed against the first and second fluids, - at least one partition wall enabling the exchange of heat between the first and second fluids, said wall being housed inside said outer casing, - a first inlet opening, for the first fluid, formed at a first end of the outer casing, - a second inlet opening, for the second fluid, formed at a second end of the outer casing, opposite the first end of said casing, - said outer casing having a long shape extending between its first and second ends, - said exchange wall extending between said first and second fluid inlet openings, - a first outlet opening, for extracting the first fluid from the outer casing, - a second outlet opening, for extracting the second fluid from the outer casing, - a first pipe enabling the first fluid to flow inside the outer casing between the first inlet opening and the first outlet opening of said first fluid, part of the wall of said pipe being made up by a first face of said exchange wall, - a second pipe enabling the second fluid to flow inside the outer casing between the second inlet opening and the second outlet opening of said second fluid, part of the wall of said pipe being up by a second face of said exchange wall opposite the first face, - said first and said second fluids being intended to flow in a counter-current manner on both sides of the exchange wall, - said first outlet opening, for the first fluid, is formed in the region of said first end of the outer casing, - said second outlet opening, for the second fluid, is formed in the region of said second end of the outer casing, - in such a manner that said second outlet opening for the second fluid, and said first inlet opening, for the first fluid, are separated by a distance equal to or greater than the length (λ) of the exchange wall, and - in such a manner that said first outlet opening for the first fluid, and said second inlet opening, for the second fluid, are separated by a distance equal to or greater than the length (λ) of the exchange wall.