Brazed plate heat exchanger

Plate heat exchanger comprising a stack of plate elements, each of which has a central heat transferring portion and a surrounding edge portion, the heat transferring portions of the plate elements being permanently joined together at several spaced places and defining between themselves flow spaces for two heat exchange fluids, the edge portions of the plate elements having parts extending around the plate elements, which parts are bent in a like direction in said stack and are permanently joined by means of a connecting material which at one time was liquid, wherein:

• each plate element is of a double-wall construction and comprises two nested thin heat transferring plates of the same size, which are pressed substantially to the same shape and which closely abut against each other but are arranged to admit a heat exchange fluid leaking out through a hole in one heat transferring plate to be conducted between the plates to the edge portion of the plate element, and
• the heat transferring plates of each plate element have brims situated outside the part of the plate element edge portion which is connected with a corresponding part of an adjacent plate element edge portion by means of said connecting material, said brims being bent so that two adjacent brims of two adjacent plate elements are spaced from each other.