Heat exchanger

A plate-fin type of heat exchanger for facilitating exchange of heat between at least two process streams, comprising;

• a matrix of heat exchange elements arranged in side-by-side heat exchange relationship, the heat exchange elements comprising diffusion bonded sandwich constructions, each such sandwich construction having two outer sheets and a superplastically expanded core sheet structure between the two outer sheets, each core sheet structure providing flow passage means for at least one process stream, adjacent heat exchange elements being in intimate thermal contact with each other over at least most of the areas of their side faces through bonded joints between them, and
• process stream inlet and outlet manifold means integral with the matrix for passing the process streams through the heat exchange elements, the manifold means penetrating the matrix from side-to-side through the thicknesses of the plate elements.