Patent ID: 8857504

Claim:
A plate heat exchanger comprising: a plurality of heat exchanger plates, which are provided beside each other and permanently joined to each other to form a plate package having first plate interspaces and second plate interspaces, wherein each heat exchanger plate has a heat transfer area and a plurality of porthole areas, each porthole area surrounding a respective porthole defined by a porthole edge, wherein each heat exchanger plate extends along a main extension plane, wherein said heat transfer area and said porthole areas extend, on one side of the heat exchanger plate, between a primary level at a distance from the main extension plane and a secondary level at a distance from and on an opposite side of the main extension plane, and wherein each of the porthole areas comprises: an annular flat area located at one of the primary and secondary level, a set of inner portions disposed on the annular flat area and distributed along the porthole edge, the inner portions being displaced from the annular flat area and extending to the other of the primary and secondary level, and a set of outer portions distributed along the annular flat area at a distance from the inner portions and being displaced from the annular flat area and extending to the other of the primary and secondary level, wherein the inner portions of each porthole area are uniformly distributed around the respective porthole, and present an equal inner angular distance between adjacent inner portions, wherein the outer portions of each porthole area are uniformly distributed around the respective porthole, and present an equal outer angular distance between adjacent outer portions, wherein each inner portion has an inner part adjoining the porthole edge and an outer segment adjoining the inner part and having an angular extension of at least 180°, and wherein the outer segment has a continuous contour and a radius R, which is allowed to vary within the range of 0.8R≦R≦1.2R along the contour, and wherein each outer portion has an inner segment adjoining the annular flat area and having an angular extension of at least 150° and wherein the inner segment has a continuous contour and a radius R′, which is allowed to vary within the range 0.8R′≦R′≦1.2R′ along the contour.