Abstract: The invention relates to an improved energy exchange structure, comprising generally parallel plates,connected to define a hollow passageway for the generally circumferential flow of fluid between an inlet and an outlet, said plates undulating in cross-section to define obliquely disposed crossing opposing valleys arranged in a spiral disposition.

Abstract: The invention relates to an improved energy exchange structure, comprising generally parallel plates, joined to define a hollow passageway for the generally circular flow of fluid between an inlet and an outlet, said plates undulating in cross-structure to define obliquely disposed crossing opposing valleys, and comprising multiple sets of generally parallel valleys and an involute disposition of said valleys.

Abstract: An improvement in circumferential flow heat exchangers of the type having a stack of heat exchange units each formed from first and second thin plates having grooves and ribs, wherein the grooves and ribs on facing surfaces of the first and second plates of a unit cross one another and cooperate to define a first flow path extending once about the interior of such unit through less than about one circumscription and grooves and ribs on facing surfaces of first and second plates of adjacent units cross one another and cooperate to define a second flow path, characterized in that the first and second plates of each unit are configured to provide the second flow path with a cross-sectional area exceeding the cross-sectional area of the first flow path.