COMPOSITE STRUCTURE FOR BOILING LIQUIDS AND ITS FORMATION

• US 3,684,007 A
• Filed: 12/29/1970
• Issued: 08/15/1972
• Est. Priority Date: 12/29/1970
• Status: Expired due to Term

• Current Assignee: UOP Des Plaines IL A NY General Partnership
• Original Assignee: Elias George Ragi
• Inventors: Ragi, Elias George
• Primary Examiner(s): Davis, Jr., Albert W.
• Application Number:
  US05/102,387
• Time in Patent Office: 595 Days
• Field of Search: 165/133,105,180,181 126/387 62/527 29/157.3
• US Class Current: 165/133
• CPC Class Codes: B21D 53/02 heat exchangers or parts thereof, e.g. radiators, condensers fins, headersmaking finned or ribbed tubes by fixing strip material or the like to tubes B21C37/22
• CPC Class Codes: F28F 13/187 especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites
• CPC Class Codes: F28F 21/084 from aluminium or aluminium alloys
• CPC Class Codes: F28F 21/085 from copper or copper alloys
• CPC Class Codes: F28F 2255/20 with nanostructures
• CPC Class Codes: Y10T 29/49378 Finned tube

Abstract

A composite metal structure for boiling liquids comprising a smooth surface metal substrate and a cover sheet bonded to the substrate with sub-surface cavities and spaced restricted openings extending through the cover sheet being joined to the cavities.

Claims

2. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is shaped to form a multiplicity of discrete sections raised from said metal substrate as said cavities.

3. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is shaped to form a multiplicity of discrete sections raised from said metal substrate as said cavities, with each raised section surrounded by unraised sections bonded to said cover sheet.

4. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is shaped to form a multiplicity of discrete sections raised from said metal substrate as said cavities, and said restricted openings have irregular non-circular cross-sections.

5. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein each cavity has an effective diameter of at least 0.006 inch.

6. A boiling to heat transfer surface formed from a composite metal structure according to claim 4 wherein said discrete sections are pyramid-shaped with the tip end of each pyramid pointing downwardly toward the substrate surface, and at least one of said restricted openings extends through each tip end.

7. A boiling to heat transfer surface formed from a composite metal structure according to claim 4 wherein said discrete sections are pyramid-shaped with the tip end of each pyramid pointing upwardly away from the substrate surface and at least one of said restricted openings extends through each tip end.

8. A boiling to heat transfer surface formed from a composite metal structure according to claim 2 wherein said cover sheet is shaped to provide fluid communication passages between at least some of said cavities adjacently positioned to each other.

9. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is metal foil shaped to form a multiplicity of discrete pyramid sections raised from said metal substrate as said cavities with the tip end of each pyramid pointing upwardly away from the substrate surface, holes of irregular non-circular cross-section pierced through said tip end of each pyramid comprise said restricted openings, and the unraised sections of said foil surround said pyramid sections with the foil bottom side bonded to the substrate.

10. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is metal foil shaped to form a multiplicity of discrete pyramid sections raised from said metal substrate with holes of irregular non-circular cross-section pierced through the tip end of each pyramid, being positioned with said tip ends pointing downwardly toward said substrate and the tip end bonded thereto with unbonded gaps between said tip end and said substrate forming said restricted openings, and the space bounded by said substrate, the shaped foil and the pyramid tip ends forming said cavities.

11. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet comprises a sheet having a series of corrugations arranged in longitudinal rows parallel to each other with separating valleys between adjacent corrugations bonded to said substrate, each corrugation having transverse slits to form corrugation sections with longitudinally alternate sections in each corrugation being transversely displaced in the same direction and the transversely aligned sections of adjacent corrugations being displaced in the same direction.

12. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein said cover sheet is bonded to said substrate and is provided with a multiplicity of spaced venturi-type openings extending through the cover sheet cross-section with the larger cross-sectional portion adjacent to said substrate and forming said cavities, and the smaller cross-sectional portion communicating with the cover sheet outer surface and forming said restricted openings.

13. A boiling to heat transfer surface formed from a composite metal structure according to claim 1 wherein the effective diameter ratio of restricted openings to cavities is less than 0.7.

14. A method for forming a boiling to heat transfer surface formed from a composite metal structure comprising:

providing a die having at least 25 spaced pyramid shaped projections per inch2 of die surface area and pressing same against a thin metal foil backed by a resilient surface to initially form discrete pyramid shaped sections in the foil;

piercing the tip ends to form holes of irregular non-circular cross-section; and

bonding the shaped foil to a smooth surface metal substrate.

15. A method according to claim 14 wherein the pierced pyramid tip ends are positioned upwardly away from said substrate, and the unraised sections of the foil bottom side are bonded to said substrate with said holes forming restricted openings to cavities formed by said pyramid shaped sections such that the cavities have an effective diameter of at least 0.003 inch and the effective diameter ratio of said restricted openings to said cavities is less than 0.8.

16. A method according to claim 14 wherein the pierced pyramid tip ends are positioned downwardly toward said substrate and bonded thereto with unbonded gaps between said tip ends and said substrate forming restricted openings to cavities formed by said pyramid shaped sections such that the cavities have an effective diameter of at least 0.003 inch and the effective diameter ratio of said restricted openings to said cavities is less than 0.8.