Method of making fin elements for heat exchangers

摘要

In a crossed fin-tube type heat exchanger wherein tubes are attached at right angles to a large number of fin elements arranged in parallel with one other, the surfaces of these fin elements are roughened to have an unevenness satisfying a relation R APPROX 1/cos theta where R is a ratio of the extended, uneven or roughened surface to the flat or smooth surface of the fin element; and theta is a contact angle for a liquid droplet in contact with the flat or smooth surface of the fin element.