A plate/fin heat exchanger (100; 200; 300), comprising: a plurality of stacked panels (360; 400; 500) defining a curvature, each of said panels (360; 400; 500) having a first corrugated sheet (130; 230; 320) defining a first set of passages and a second corrugated sheet (140; 240; 310) defining a second set of passages; each of said first (130; 230; 320) and second (140; 240; 310) corrugated sheets including multiple aligned corrugations, and wherein said corrugations (132; 232) of said first corrugated sheet (130; 230; 320) are not aligned with said corrugations of said second corrugated sheet (140; 240; 310), and wherein each of said corrugations (132, 142; 232) has a corrugation height defined as a length of said corrugation tangential to a curvature of the plate/fin heat exchanger (100; 200; 300); wherein each of said first corrugated sheets (130; 230; 320) includes axially aligned corrugations defining a wedge shaped radial cross section; characterised in that the plate/fin heat exchanger (100; 200; 300) further comprises: an isolation sheet disposed between said first corrugated sheet (130; 230; 320) and said second corrugated sheet (140; 240; 310) of each of said stacked panels (360; 400; 500); and a radially outer wall (120; 220) contacting each of said stacked panels (360; 400; 500) and a radially inner wall (110; 210) contacting each of said stacked panels (360; 400; 500), wherein one of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow input (150; 250) and the other of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow output, and said gas flow input (150; 250) and said gas flow output are connected by said second set of passages, wherein each of said radially inner wall and said radially outer wall include a plurality of passages (252, 254, 255, 256, 257), such that gas passing through said second set of passages has a serpentine flowpath and crosses the heat exchanger at least twice. a plurality of stacked panels (360; 400; 500) defining a curvature, each of said panels (360; 400; 500) having a first corrugated sheet (130; 230; 320) defining a first set of passages and a second corrugated sheet (140; 240; 310) defining a second set of passages; each of said first (130; 230; 320) and second (140; 240; 310) corrugated sheets including multiple aligned corrugations, and wherein said corrugations (132; 232) of said first corrugated sheet (130; 230; 320) are not aligned with said corrugations of said second corrugated sheet (140; 240; 310), and wherein each of said corrugations (132, 142; 232) has a corrugation height defined as a length of said corrugation tangential to a curvature of the plate/fin heat exchanger (100; 200; 300); wherein each of said first corrugated sheets (130; 230; 320) includes axially aligned corrugations defining a wedge shaped radial cross section; characterised in that the plate/fin heat exchanger (100; 200; 300) further comprises: an isolation sheet disposed between said first corrugated sheet (130; 230; 320) and said second corrugated sheet (140; 240; 310) of each of said stacked panels (360; 400; 500); and a radially outer wall (120; 220) contacting each of said stacked panels (360; 400; 500) and a radially inner wall (110; 210) contacting each of said stacked panels (360; 400; 500), wherein one of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow input (150; 250) and the other of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow output, and said gas flow input (150; 250) and said gas flow output are connected by said second set of passages, wherein each of said radially inner wall and said radially outer wall include a plurality of passages (252, 254, 255, 256, 257), such that gas passing through said second set of passages has a serpentine flowpath and crosses the heat exchanger at least twice. an isolation sheet disposed between said first corrugated sheet (130; 230; 320) and said second corrugated sheet (140; 240; 310) of each of said stacked panels (360; 400; 500); and a radially outer wall (120; 220) contacting each of said stacked panels (360; 400; 500) and a radially inner wall (110; 210) contacting each of said stacked panels (360; 400; 500), wherein one of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow input (150; 250) and the other of said radially inner wall (110; 210) and said radially outer wall (120; 220) comprises a gas flow output, and said gas flow input (150; 250) and said gas flow output are connected by said second set of passages, wherein each of said radially inner wall and said radially outer wall include a plurality of passages (252, 254, 255, 256, 257), such that gas passing through said second set of passages has a serpentine flowpath and crosses the heat exchanger at least twice.