Heat exchanger, methods and means for making same

A method for producing a heat exchange element having great efficiency, limited bulk, small weight, low production cost and, generally, intrinsic stability, characterized in that it comprises the following steps:

• producing in a mold (50), by thermo-blow moulding or hydroforming, a preform (32) made of a suitable material, constituted by a stack of globally biconvex bellows (34), relatively deep relative to the transverse dimension of the preform and comparable to those of an accordion, said bellows comprising elongated central parts, equipped with end connectors (40-42), flanks (33-35), tips (36) and bottoms (38) having respectively appropriate shapes so that these flanks (33-35) have a much greater rigidity than those of the bottoms (38) and the tips (36), said stack itself being equipped with two transverse connections (28-30), centred on the stacking axes (25-27) of said end connectors (40-42);
• the elements constituting this preform (32) having suitable temperatures, flexibilities and elasticities, applying an internal depression and/or external compression forces to them, parallel to the stacking axis of the bellows, up to the point where the thus-produced compressed part (10) becomes a stack of pairs of hollow plates (12-22), communicating (16) and globally symmetrical, with substantially constant small internal thickness (14) and spacing (18)
• allowing the single-piece part (10) so manufactured to cool, while keeping it compressed;
• if necessary, after cooling the thus-produced part (10), surrounding it with a member (81) ensuring its clamping, in order to maintain at their initial values the spaces between the walls of the pairs of plates (22).