Abstract: A heat-exchanger element of the type consisting of two sandwiched metal sheets, deformed so as to define between themselves a flow channel, has a number of apertures in the portion of the element not deformed. The one heat-exchanging fluid passes through the channel and the other through the apertures, generally in a direction perpendicular to the sandwich interface. In a preferred embodiment the apertures are formed by a punching operation in the way that tongue-like flaps are formed which affect the direction of flow, create turbulence and may serve as means spacing or supporting adjacent elements.

Abstract: The invention relates to heat-exchangers, especially of the type where the one medium is constituted by a gas or a vapor. It has a plurality of elongate elements which between themselves define the flow channels of the mediums. According to the invention, the elements comprise cores made of a material of high heat-conducting capacity. The cores are, at least partly, provided with a covering made of another material. The covering performs two functions; it keeps the cores fixed in their proper locations and they shield off the cores from direct contact with one of the two mediums. The covering may be metal or a synthetic resin.