Patent ID: 7108053

Claim:
A plate heat exchanger comprising: a plurality of quadrilateral partition plates arranged in a stack, wherein each partition plate has a first and second major sides and comprises (a) a generally quadrilateral center portion comprising a major portion of the area of the plate and having a generally uniform plate thickness; (b) a first solid edge region having the thickness greater than the thickness of said center portion; (c) a second solid edge region, opposite said first solid edge region, having a thickness greater than the thickness of said center portion, said first and second solid edge regions being on a first side of the plate; (d) a third solid edge region having a thickness greater than the thickness of said center portion; and (e) a fourth solid edge region, opposite said third solid edge region, having a thickness greater than the thickness of said center portion, said third and fourth solid edge regions being on a second side of the plate and on opposite edges than said first and second solid edge regions; wherein each of said solid edge regions is on the partition plate surface; wherein each plate is joined to an adjacent plate along abutting first and second edge regions or along abutting third and fourth edge regions, thereby defining a flow channel between each plate and an adjacent plate; and wherein successive pairs of plates within said stack are arranged at an angle of 90° relative to a previous pair of partition plates, thereby defining flow channels alternating in a first direction and a second direction.