Production of heat transfer element

• US 5,482,744 A
• Filed: 02/22/1994
• Issued: 01/09/1996
• Est. Priority Date: 02/22/1994
• Status: Expired due to Fees

• Current Assignee: Star Refrigeration Ltd.
• Original Assignee: Star Fabrication Limited
• Inventors: Pearson, Stephen F.
• Primary Examiner(s): LUSIGNAN, MICHAEL R
• Application Number:
  US08/199,475
• Time in Patent Office: 686 Days
• Field of Search: 427/191, 427/192, 427/455, 427/456, 427/427, 427/424
• US Class Current: 427/455
• CPC Class Codes: C23C 4/12 characterised by the method of spraying
• CPC Class Codes: F28F 13/187 especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites

Abstract

A heat transfer element (2) for use in boiling a liquid is produced by spraying a substrate, such as a heat exchanger tube, with a plasma of liquified metal particles and concurrently spraying the substrate with liquid carbon dioxide to provide a cooling effect. Preferably the metal particle spray (4) and the carbon dioxide spray (8) are spaced apart, and there is relative movement between the sprays and the substrate, such that a given area of the substrate is precooled by the cold carbon dioxide just prior to liquified metal particles impinging thereon. A shroud (6) may assist in directing the liquid carbon dioxide first onto the substrate, then into the spray of liquified metal particles.

Claims

1. A process for the production of a heat transfer element for boiling a liquid which comprises:

spraying a substrate with molten metal particles; and

concurrently spraying the substrate with liquid carbon dioxide;

to form a heat transfer element having a matrix of metal particles attached to the substrate.

2. A process according to claim 1 wherein the liquid carbon dioxide is sprayed onto a given area of the substrate such that the substrate is precooled before molten metal particles are sprayed onto said area.

3. A process according to claim 2 wherein the liquified metal particles and the liquid carbon dioxide are sprayed onto the substrate from spaced adjacent locations, the substrate being moved relative to the liquified metal spray;

such that the liquid carbon dioxide is sprayed onto a given area of the substrate before the molten metal particles.

4. A process according to claim 3 wherein the liquid carbon dioxide is sprayed into a shroud which directs the .liquid carbon dioxide first onto the substrate to cool the substrate, and then in a direction toward the spray of molten metal particles.

5. A process according to claim 1 wherein the substrate is in the form of a tube.

6. A process according to claim 1 wherein the substrate is formed of a metal selected from the group consisting of cupro-nickel, copper, steel and stainless,steel.

7. A process according to claim 1 wherein the metal particles are formed of aluminium.

8. A process according to claim 1 wherein the matrix of metal particles has a thickness less than 250 microns.

9. A process according to claim 1 wherein the molten metal particles have a particle size in the range 10 to 60 microns.