Patent ID: 8215015

Claim:
A method for manufacturing a modular heat exchanger, the method comprising the steps of: assembling and fixturing a headerless core comprising substantially parallel tubes separated by centers that extend parallel to the tubes, the tubes and the centers being formed of metal alloys, at least some of the tubes and the centers being clad with a braze alloy that has a melting temperature near but below the melting temperature of the metal alloys, each of the tubes having oppositely disposed open ends and an oblong cross-section defining oppositely-disposed planar surfaces that are spaced from a longitudinal axis of the tube, at least one of the planar surfaces of each tube contacting at least one of the centers, the headerless core being fixtured so that each adjacent pair of the tubes is spaced apart by one of the centers and spacings between the tubes and spacings between the open ends of the tubes are determined by the centers so as to establish a pre-brazed tube spacing pattern of the headerless core, the fixturing of the headerless core also minimizing core shrinkage from compaction of the tubes and centers during brazing at a brazing temperature of at least the melting temperature of the braze alloy and at which the tubes and centers thermally expand; brazing the headerless core at the brazing temperature to yield a brazed headerless core with a post-brazed tube spacing pattern that enables assembly of the tubes with apertures that are defined in at least one header and correspond to the post-brazed tube spacing pattern of the brazed headerless core, wherein spacings between the open ends of the tubes are not established by any structural element that is in addition to the braze alloy and centers and serves as a permanent and integral tube-end alignment fixture of the brazed headerless core; installing elastomeric sealing means in the apertures of the header, the elastomeric sealing means having openings that correspond to the post-brazed tube spacing pattern of the brazed headerless core; and then assembling the brazed headerless core with the header, wherein an end of each of the tubes is received in a corresponding one of the openings of the elastomeric sealing means to form fluid-tight seals between the tubes and the header, the brazed headerless core being a removable monolithic brazed module of the modular heat exchanger.