Abstract: A heat exchanger having alternating first and second fluid passages with perpendicular flow directions separated by channels, spacer bars located at sides of the first fluid passages, side walls located at sides of the second fluid passages that are formed by folded portions of pairs of adjacent channels coupled to form a joint, fins located within the fluid passages, and side panels located at and sealing oppositely disposed ends of the series of alternating fluid passages. The heat exchanger can be produced with methods that include providing and advancing a continuous, elongated strip of material along a path, flattening the strip, folding edges of the strip to define partial fold patterns, cutting a formed portion of the strip to produce one of the channels, and assembling pairs of the channels such that the respective partial fold patterns interlock or overlap to define a joint.

Abstract: A heat exchanger having alternating first and second fluid passages with perpendicular flow directions separated by channels, spacer bars located at sides of the first fluid passages, side walls located at sides of the second fluid passages that are formed by folded portions of pairs of adjacent channels coupled to form a joint, fins located within the fluid passages, and side panels located at and sealing oppositely disposed ends of the series of alternating fluid passages. The heat exchanger can be produced with methods that include providing and advancing a continuous, elongated strip of material along a path, flattening the strip, folding edges of the strip to define partial fold patterns, cutting a formed portion of the strip to produce one of the channels, and assembling pairs of the channels such that the respective partial fold patterns interlock or overlap to define a joint.