Primary surface heat exchanger and manufacture thereof

Claim 1

A primary surface heat exchanger comprising at least one channel element bound by two thermally conductive walls being spaced by edge portions, said channel element having an entrance opening at one end, an exit opening at the opposite end, and a multiplicity of isostress contours on a portion of each wall surface with substantially uniformly disposed unidirectional wall-supporting projections formed from each wall, said projections having load-bearing segments at their extremities which are shaped for mating over a substantial area with similar type load-bearing segments on wall-supporting projections of a second isostress surface and formed wIth the wall between and surrounding said load-bearing segments being continuously curved and devoid of local mechanical loading; said isostress contours and wall-supporting projections having a dimensional relationship therebetween defined by a H/D ratio of between about 0.05 and about 0.2; a D/d ratio of between about 3 and about 10, a D dimension of between about 0.2 and 2.5 inches and a wall thickness between about 0.003 and about 0.25 inch; wherein H equals the maximum height measured perpendicularly from a surface which contains the extremities of the wall-supporting projections enclosing an isostress contour to the innermost crest of the isostress contour; D equals the spacing between the centers of the closest adjacent wall-supporting projections on the surface of the element; and d equals the equivalent diameter defined by the ratio 4a/p whereby a equals the area of the load-bearing segment of the wall-supporting projection and p equals the perimeter of said load-bearing segment.