Exchange body suitable for placing in a pipe or a chamber to guide the flow of the first fluid into or towards the exchange body which includes: - a component suitable for being located at least partially in the said pipe, the said component being made up of two sheets (30,31) made of a heat conducting material, the said sheets (30,31) being connected to each other at least in the vicinity of their longitudinal edges (30A,30B,31A,31B) to define between them one or more internal channels for the said second fluid, the said component being coiled to form a structure, at least partially spiralled, extending into the said pipe so as to define in the pipe between the surfaces of the adjacent spirals one or more channels for the first fluid, - at least one, preferably at least two essentially radial distributors to convey the said second fluid into the component, in the vicinity of a first longitudinal edge (30A, 31A) at the level of the different coils, and at least one, preferably two essentially radial collectors to collect the said second fluid after it passes into the said component, the said collector being suitable for collecting the said second fluid in the vicinity of the second longitudinal edge (30B,31B) at the level of the different coils, in which the first sheet and the second sheet, forming the component, are bent to form respectively a first series of channels and a second series of channels, the edge of the channels of the first series of the first sheet turned towards the second sheet contacting the edge of one or more channels of the second series of the second sheet, forcing the said second fluid to take a path between the distributor and the collector, the said path being formed both by the channels of the first series and the channels of the second series. - a component suitable for being located at least partially in the said pipe, the said component being made up of two sheets (30,31) made of a heat conducting material, the said sheets (30,31) being connected to each other at least in the vicinity of their longitudinal edges (30A,30B,31A,31B) to define between them one or more internal channels for the said second fluid, the said component being coiled to form a structure, at least partially spiralled, extending into the said pipe so as to define in the pipe between the surfaces of the adjacent spirals one or more channels for the first fluid, - at least one, preferably at least two essentially radial distributors to convey the said second fluid into the component, in the vicinity of a first longitudinal edge (30A, 31A) at the level of the different coils, and at least one, preferably two essentially radial collectors to collect the said second fluid after it passes into the said component, the said collector being suitable for collecting the said second fluid in the vicinity of the second longitudinal edge (30B,31B) at the level of the different coils, in which the first sheet and the second sheet, forming the component, are bent to form respectively a first series of channels and a second series of channels, the edge of the channels of the first series of the first sheet turned towards the second sheet contacting the edge of one or more channels of the second series of the second sheet, forcing the said second fluid to take a path between the distributor and the collector, the said path being formed both by the channels of the first series and the channels of the second series.