Patent ID: 8079508

Claim:
A heat exchanger method, comprising: brazing within a vacuum a corrugated sheet, a first lateral bar and a second lateral bar to an upper sheet and a lower sheet such that the corrugated sheet is between the first lateral bar and the second lateral bar, and the corrugated sheet is between the upper sheet and the lower sheet, whereby the corrugated sheet, the first lateral bar, the second lateral bar, the upper sheet and the lower sheet comprises a first corrugated layer that defines a first fluid passageway; creating a plurality of corrugated layers each in a substantially same manner to that of the first corrugated layer; and after creating the plurality of corrugated layers by brazing within a vacuum, rearranging the plurality of corrugated layers in an alternating stacked arrangement with a plurality of open layers, wherein each open layer comprises a first spacer bar and a second spacer bar interposed between the upper sheet of one corrugated layer and the lower sheet of a second corrugated layer, wherein: a) the first spacer bar, the second spacer bar, the upper sheet of the one corrugated layer, and the lower sheet of the second corrugated layer define a second fluid passageway; b) the first fluid passageway and the second fluid passageway are in counter-flow relationship to each other; c) the first lateral bar and the first spacer bar extend longitudinally in substantially parallel relationship to each other; d) the second fluid passageway runs generally parallel to the first spacer bar and the second spacer bar; and e) the first fluid passageway has a first width between the first lateral bar and the second lateral bar, the second fluid passageway has a second width between the first spacer bar and the second spacer bar, and the second width is greater than the first width.