Abstract: Heat exchangers including elongated hollow housings having inlet and outlet ports for circulating first and second fluid media through the housings and whereby each housing includes a heat exchanging core that is formed of a single, folded corrugated sheet. The sheet is formed with a series of parallel peaks and valleys running angularly to the direction of the sheet so that when the sheet is folded there are defined a plurality of channels by reason of the crisscross pattern of peaks and valleys crossing one another at right angles in the tightly folded configuration of the core. The folded configuration provides discrete respective channels for conveying the first and second fluid media. In the preferred embodiment of the heat exchangers, every fold of the corrugated sheet is in contact with the housing interior and thereby form alternating isolated channels without the need to use any top, bottom or side seals around the core.

Abstract: An apparatus and method are described for thoroughly sealing off the extreme ends of a corrugated folded plate (core) heat exchanger. Instead of using end caps to seal off the two ends of the heat exchanger, the ends are first compressed or “crushed” into a vertical seam, thereby maximizing the density of the core. The crushed ends are then pinched and/or trimmed and the seam is then welded closed. Another variation is to spin the ends of the heat exchanger so that the ends taper to a very small opening while also maximizing the density of the core. The small opening is then welded shut.