Counterflow heat exchanger

Claim 1

A heat exchanger formed of a plurality of superimposed units sealed together, each of said units comprising: a plurality of parallel elongated hollow heat exchange tubes; inlet and outlet headers located at respective ends of said plurality of said elongated heat exchange tubes and in fluid communication with the hollow interiors of said heat exchange tubes; each of said headers comprising a tube sheet perpendicular to said tubes for supporting the tubes at one end, top and bottom plate members, and said plate members forming flow directing means for directing incoming tube side fluid along a path toward said tube sheet oblique with respect to said tube sheet, said flow directing means including an end face defining an opening to the header interior and a closed end face, said end face defining said opening and said closed end face being joined at an apex and extending obliquely from said apex toward said tube sheet; wherein said top and bottom plate members define surfaces which are gradually and continuously sloped both to converge toward each other at said closed end face and to diverge toward said opening; and wherein the end faces providing said openings are sealed to like adjacent end faces to prevent fluid flow therebetween and said closed end faces are spaced apart to allow sheet side fluid to enter and exit therebetween in a direction oblique to said tube sheet while passing in contact with the exteriors of said elongated heat exchange tubes.