Enhanced heat transfer surfaces

• US 4,846,267 A
• Filed: 03/14/1988
• Issued: 07/11/1989
• Est. Priority Date: 04/01/1987
• Status: Expired due to Fees

• Current Assignee: BOC Group Pty Limited (Linde Plc)
• Original Assignee: BOC Group Pty Limited (Linde Plc)
• Inventors: Krueger, Paul C., Shattes, Walter J., Bandyopadhyay, Nikhiles
• Primary Examiner(s): Fogarino, Margaret A.
• Application Number:
  US07/168,035
• Time in Patent Office: 484 Days
• Field of Search: 165/133, 428/141, 428/143, 428/148
• US Class Current: 165/133
• CPC Class Codes: C22F 1/04 of aluminium or alloys based thereon
• CPC Class Codes: C23F 1/20 for etching aluminium or alloys thereof
• CPC Class Codes: F28F 13/187 especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites
• CPC Class Codes: Y10T 428/12993 Surface feature [e.g., rough, mirror]
• CPC Class Codes: Y10T 428/24413 Metal or metal compound

Abstract

Aluminum alloys suitable for fabrication into plate and fin type heat exchangers are subjected to a chemical etching procedure in order to improve the heat transfer efficiency thereof. Applicants have found that a high temperature heat treatment of an aluminum alloy plate material to produce a precipitate, followed by exposure to an etching composition, results in a heat exchanger surface modified by the formation of pits. The heat exchangers so modified may be advantageously used in the reboiler/condensor section of air separation units.

Claims

1. A heat exchanger wall for transferring heat to a boiling liquid in a heat exchange apparatus which comprises a boiling surface comprised of an aluminum alloy having nucleation site pits formed on said surface by etching a precipitate therein, wherein said nucleation site pits entrap vapor bubbles to provide nucleation sites, the nucleation site pits having an average size to 0.5 to 5 microns.

2. The heat exchanger wall of claim 1, wherein said heat exchanger wall is part of a fin type heat exchanger.

3. The heat exchanger wall of claim 1, wherein the density of said pits are in the range of 10⁴ to 10⁶ per square centimeter.