Patent ID: 7204297

Claim:
A plate-type heat exchanger comprising a stack of double-walled heat exchanger plates which are permanently interconnected and each include two plate members having a central heat transfer portion and an edge portion bent upwardly with respect to the plane of the central heat transfer portion, separate flow passage spaces for at least two heat exchange fluids being defined between the double-walled heat exchanger plates, the two plate members entering into close mutual engagement at least partly in the area of the central heat transfer portion and the upwardly bent edge portion yet Permitting heat exchange fluid between the plate members which gets to the upwardly bent edge portions to exit through an aperture between the upwardly bent edge portions, the upwardly bent edge portions being formed respectively with an outer edge, characterized in that the respective outer edges of the two plate members of the double-walled heat exchanger plates are spaced from each other in that outer edges of adjacent plate members of two neighboring double-walled heat exchanger plates in the stack are disposed in close mutual engagement.