Plate-type heat exchanger

Claim 1

A heat exchanger in the form of a stack of plates, comprising: a plurality of diagonally symmetrical like parallel plates, alternate plates being disposed at 90 degrees with respect to adjoining plates, each of the plates having a base portion substantially on and defining a base plane; each of the plates having a pair of generally parallel opposite first outer edges and two generally parallel second outer edges bridging and generally perpendicular to the respective first outer edges; respective lips bend upward from the base plane along said first outer edges and forming and lying on a connection plane substantially parallel to the base plane; each lip having a first end formation defining a portion of said base plane spaced in from said first outer edge and adjacent one of said second outer edges, and having an opposite second end formation defining a portion of said base plane adjacent both said first outer edge and the other of said second outer edges, said end formations being arranged in directions opposite each other whereby each of said outer edges has a portion lying in said base plane and a portion lying in said connection plane; whereby when said plates are stacked 90 degrees with respect to one another, said connection plane of one plate underlies said base plane of an adjacent plate such that the first outer edges of said one plate underlie the second outer edges of said adjacent plate and the connection plane of said one plate is in full contact with an edge portion of the base plane of said adjacent plate, said second end formations of said one plate underlying said first end formations of said adjacent plate; means for securing the plates together in a stack to form respective sets of flow passages sealed from each other, and parallel to the planes, the sets of flow passages being disposed generally perpendicularly to each other.