Lightweight, compact heat exchanger

Claim 1

A heat exchanger comprising: a plurality of tubes defining a plurality of first flow paths, each tube including a first generally U-shaped member having a base portion and two legs generally perpendicular to the base portion, one leg further including two folds which define a trough therebetween; a second member shaped identically to the first member, said second member rotated 180° with respect to the first member such that the leg of the first member slides within the trough of said second member and said leg of said second member slides within the trough of said first member, each of said tube having corrugated fins therein; a plurality of pairs of generally C-shaped bars spacing said plurality of tubes apart from adjacent tubes, said bars being cross-wise to said tubes and each pair of bars defining a plurality of second flow paths; an extended surface heat transfer element between each pair of bars; an integral lanced tab at each end of said plurality of bars, each tab folded over itself toward the heat exchanger center and capturing a portion of said extended surface heat transfer element; side plates on each side of said heat exchanger, said side plates spaced from one of said tubes by a pair of bars; means for securing said first members, bars and said side plates together and for isolating said first and second flow paths from each other; and manifold means, sealingly attached to said tube ends, for disbursing a working fluid into said plurality of said first flow paths at one end of said tubes and for collecting said working fluid at the opposite ends of said tubes.