Heat exchanger with spirally wound sheets

Claim 1

A heat exchanger comprising within an enclosure a spirally wound coil in a plurality of turns of a pair of elongated sheet-metal bands sealed together at their short ends and formed alternately along their longitudinal edges with an open and a sealed segment, the spiral formed by said coil defining at least two axial flow passages for respective heat-exchange fluids separated from one another by at least one of said bands, and means forming respective compartments in said enclosure communicating separately with said passages at opposite axial ends of the coil to pass said heat-exchange fluids separately and axially through said passages, open and sealed ones of such segments alternating along said longitudinal edges whereby, upon spiral coiling of the bands, the sealed segments alternate with open segments radially from the axis of the spiral and the sealed and open segments are disposed in a checkerboard pattern at opposite ends of the spiral.