Plates of a heat exchanger plate pack are formed by a stack of plates defining at least two independent fluid flow circuits, each circuit comprising a central heater part and a border with a smooth surface. The binder is applied to the semi-finished fiber material or the fiber preform and subsequently activated through increasing the temperature by conducting an electrical current through the carbon fibers of the preform. The location of the device may be correlated with certain user preferences stored on the server computer system. Another portion designated as a regulating has body with the stem extended to fill the tubular space longitudinally separating inlet and outlet ports. without the use of a stop edge, indentation, template or die, whereby the attained three-dimensional shape is permanently preserved after cooling during which the material blank is kept.