Abstract: A heat transfer surface for nucleate boiling of liquids is formed on the outer surface of a heat exchanger tube. Helical ridges having two fins each encase the tube. A fin at each ridge is angled toward the adjacent fin on the adjacent ridge forming a gapped cavity therebetween. The method of making the tube includes rolling alternating deep grooves and shallow grooves in the outside surface of the tube and then flaring the fins to form the gapped cavity.

Abstract: Tube passages slightly bigger than the tubes are formed in a plate. A soft resilient sheet is placed on one side of the plate. The tube is forcibly inserted in the tube passages and draws a portion of the sheet which is then cut. In the assembly the sheet, which has a bigger thickness than the interval between the tube and the tube passage, forms a flange beyond the tube plate.

Abstract: A conduction heat transfer connection is made between a heat source and a heat sink which is flexible so as to adapt to variations in distance between the source and sink and which maintains the required force on the heat source to obtain the required heat transfer across the junction therebetween. The connection consists of a heat conductive metallic foil bundle of sufficient thickness to contact sufficient surface area of the heat source to provide the required heat transfer and of sufficient thinness to be flexible enough to absorb the expansion and contraction due to temperature changes as well as the differences in distance between the heat source and sink and of sufficient length to contact at or near the other end thereof the heat sink.