Patent ID: 7415764

Claim:
A method of assembly of a recuperator core, comprising: (a) providing a supply of first heat exchanger foils and a supply of second heat exchanger foils, the first heat exchanger foils having a first fin fold orientation and the second heat exchanger foils having a different second fin fold orientation; (b) forming an indexing indicator on each of said first heat exchanger foils and each of said second heat exchanger foils, such that an improper assembly of two first heat exchanger foils or two second heat exchanger foils is visibly distinguishable from a proper assembly of one first heat exchanger foil and one second heat exchanger foil; (c) assembling a plurality of recuperator core segments, each recuperator core segment including one of said first heat exchanger foils and one of said second heat exchanger foils; (d) providing each of said recuperator core segments with an offset indexing lip alone a radially inner edge of the recuperator core segment, said offset indexing lip being consistently oriented relative to the first heat exchanger foil and the second heat exchanger foil of each recuperator core segment; and (e) forming each recuperator core segment into an involute curve, the curve having a concave side consistently oriented relative to the offset indexing lip, so that when a plurality of said recuperator core segments are stacked together to form a core, the indexing lips of adjacent recuperator core segments nest together and the first heat exchanger foil of each recuperator core segment is adjacent the second heat exchanger foil of the adjacent recuperator core segment, so as to prevent nesting of the heat exchanger foils of adjacent recuperator core segments.