Lanced fin heat exchanger

A cross finned tube heat exchanger comprising:

• a multiplicity of fin plates of a suitable area arranged in substantially parallel, closely spaced relation;
• and
• a plurality of heat transfer tubes passing through aligned openings in said fin plates and kept in intimate contact with said fin plates to allow a heat transfer medium flowing through said heat transfer tubes to exchange heat with another heat transfer medium flowing across the surfaces of said fin plates;
• wherein the improvement comprises:
• the fin plates each having louvered portions interposing the aligned openings in the fin plates, the louvered portions in each fin plate defining a nominal plane and including a plurality of louvers and a base, the base having base portions including rise portions and flank portions, three each, which alternate in a transverse direction across the width of the fin plate, with the rise portions and flank portions forming three peaks being a central peak and two outer peaks, the peaks being raised in a first direction perpendicular to the nominal plane, the rise portions and flank portions further forming two valleys in the opposite, second direction perpendicular to the nominal plane, the valleys spaced from each other and each being between the central peak and an outer peak, the rise portions being substantially parallel to each other and intersecting the nominal plane at a first acute angle and the flank portions being substantially parallel to each other and intersecting the nominal plane at a second acute angle substantially equal in degree and opposite in direction to the first acute angle, each rise portion and flank portion having a louver thereon, each louver being a resident louver of the base portion which has the louver thereon, and each resident louver having a base portion being a residence base portion therefor, each louver having a single louver wall, the louver wall of each louver between the outer peaks being raised in the first direction from the residence base portion of which the louver is resident, the louver wall of each louver inward of the outer peaks being substantially parallel to the residence base portion of which the louver is resident, the louvers on the rise portions and flank portions outward of the outer peaks being sloped inward and upward in the first direction the same distance as the distance which the louver walls of the louvers between the outer peaks are raised, the louvers outward of the valleys being split louvers and the louvers between the valleys being full louvers, each of the louvers having a substantially uniform width and all the louvers having a width substantially equal to the width of each other.