Method of making an annular tube-fin heat exchanger

A method of making a heat exchanger, including the steps of:

• a. providing a tube made of a relatively rigid heat conductive metal and a compressible fin annulus comprising corrugated thin metal deformable material,
• b. inserting the compressible fin annulus in said tube and providing a central support therefor, said support rigidly backing said fin annulus,
• c. applying a radial compressive force to said fin annulus so that all parts thereof are in closely contacting compressive relation to the interior wall of said tube irrespective of irregularities in fin height, the application of compressive forces being accomplished by displacing the tube wall radially inwardly,
• d. the fin annulus reacting upon said central support and the tube wall deforming to conform to fin irregularities,
• e. prior to applying said radial compressive force inserting in at least one end of said tube a relatively incompressible closure member,
• f. said member having a cross sectional dimension to have a relatively loose fit in said tube and the tube wall in being radially inwardly displaced encountering between its ends relatively compressible means in the form of said fin annulus and at least at said one end thereof encountering the firm resistance of said closure member,
• g. a single contracting tube therefore closing tightly at least at said one end on an inserted closure member and between its ends engaging and applying a compressive pressure to said fin annulus,
• h. and metallurgically bonding together the parts so assembled.