welded to inner annulus 86 referring to fig6 core 41 of recuperator 23 is bounded by outer annular housing 40 and inner cylinder 122 defining inner annulus 86 as also shown in fig7 inner cylinder 122 is formed with high pressure inlets 127 and high pressure outlets 128 recuperator core is disposed such that each cold channel 80 is in fluid communication with one high pressure inlet 127 and one high pressure outlet 128 to allow high pressure cool fluid stream 100 to flow therethrough referring to fig7 both high pressure inlets 127 and high pressure outlets 128 may be formed in one embodiment by axially slitting or slicing inner cylinder 122 and then bending the sliced material to form louvers 131 and 132 respectively in operation high pressure cool fluid stream 100 exits compressor 30 and enters cold channels 80 through inlet 127 travels along the axial length of the cold channels and eventually exits through outlets 128 in a preferred embodiment hot fluid stream 110 flows through hot channels 82 in the opposite to cool fluid stream 100 hot channels 82 are formed with completely open axial ends and thus hot fluid stream 100 is substantially evenly distributed throughout each hot channel referring to fig8 cold channels 80 and hot channels 82 at the outer diameter near outer annulus 84 of recuperator core 41 are designated as 80 o and 82 o respectively while at the inner diameter near inner annulus 86 are designated 80 i and 82.