Abstract

A heat exchange device having a vessel and heat transfer core means including at least two tubular conduits in fluid communication with the vessel, the tubular conduits being spaced apart to form an air passageway therebetween. A spacer member is positioned between and in heat exchange relationship with the tubular conduits, the spacer member comprising a unitary strip of metal corrugated or folded back and forth to form a plurality of fin elements each having an essentially planar base member between the fold edges. Each spacer member has its longitudinal axis in parallel relationsip to the longitudinal axes of the tubular conduits with the fin elements dividing the air passageway between the conduits into a plurality of smaller passageways. Each planar base member has a plurality of louvers therein, the louvers being integral with and extending laterally of the planar base members and arranged in groups having a support portion therebetween.The improvement comprises the unitary strip of metal being very thin with a hem flange extending substantially the length of the strip through the support portions between groups of louvers. The hem flange forms a support column in each planar base member adapted to resist buckling in a direction transversely of the planar base member.The unitary strip of metal has an average thickness of 0.001 to 0.0008 inches minimum and the hem flange thickness is approximately triple the average metal thickness.