Method for making brazed heat exchanger and apparatus

• US 7,677,300 B2
• Filed: 06/29/2007
• Issued: 03/16/2010
• Est. Priority Date: 05/30/2003
• Status: Active Grant

• Current Assignee: UOP Llc (Honeywell International Inc.)
• Original Assignee: UOP Llc (Honeywell International Inc.)
• Inventors: Held, Dennis P. Sr., Godry, Thomas J., O'Neill, Patrick S.
• Primary Examiner(s): Duong; Tho v
• Application Number:
  US11/824,263
• Publication Number:
  US 20080041573A1
• Time in Patent Office: 991 Days
• Field of Search: 165/166, 165/133, 165/905, 165/167, 165/152, 165/140, 629/03, 629/05, 626/43, 428/550
• US Class Current: 165/166
• CPC Class Codes: F25J 2250/02 Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
• CPC Class Codes: F25J 2250/20 Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams
• CPC Class Codes: F25J 2290/32 Details on header or distribution passages of heat exchangers, e.g. of reboiler-condenser or plate heat exchangers
• CPC Class Codes: F25J 2290/44 Particular materials used, e.g. copper, steel or alloys thereof or surface treatments used, e.g. enhanced surface
• CPC Class Codes: F25J 3/04412 in a classical double column flowsheet, i.e. with thermal coupling by a main reboiler-condenser in the bottom of low pressure respectively top of high pressure column
• CPC Class Codes: F25J 5/002 for continuously recuperating cold, i.e. in a so-called recuperative heat exchanger
• CPC Class Codes: F25J 5/005 in a reboiler-condenser, e.g. within a column
• CPC Class Codes: F28D 9/0062 the conduits for one heat-exchange medium being formed by spaced plates with inserted elements F28D9/0012, F28D9/0025, F28D9/0081, F28D9/04 take precedence
• CPC Class Codes: F28F 13/18 by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
• CPC Class Codes: F28F 13/187 especially adapted for evaporator surfaces or condenser surfaces, e.g. with nucleation sites
• CPC Class Codes: F28F 21/081 Heat exchange elements made from metals or metal alloys
• CPC Class Codes: F28F 21/089 Coatings, claddings or bonding layers made from metals or metal alloys F28F19/06 takes precedence
• CPC Class Codes: F28F 2250/108 with combined cross flow and parallel flow
• CPC Class Codes: F28F 2275/04 by brazing brazing heat exchangers B23K1/0012
• CPC Class Codes: Y10T 29/4935 Heat exchanger or boiler making

Abstract

Disclosed is a heat exchanger comprising a boiling passage and cooling passage defined by opposite sides of metal walls. Layers of brazing material between the metal walls and a spacer member bond components of the heat exchanger together. An enhanced boiling layer (EBL) comprising metal particles bonded to each other and to a boiling side of the metal wall provides nucleate boiling pores to improve heat transfer. The EBL has a melting temperature that is higher than the melting temperature of the brazing material. Also disclosed is a process for assembling the heat exchanger.

Claims

1. A heat exchanger comprising:

a plurality of metal walls, each metal wall comprising two sides, a boiling side with a porous, enhanced boiling layer comprising brazed, thermally conductive particles comprising a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminium and silicon integrally bonded together and metallurgically bonded to the boiling side and a cooling side, said boiling side of said plurality of metal walls defining a boiling passage and said cooling side of said plurality of metal walls defining a cooling passage and each of said plurality of metal walls further including a bonding surface;

a spacer member for spacing metal walls from each other;

a layer of metal between said bonding surfaces of said metal walls and said spacer member in said heat exchanger, said layer of metal having a melting temperature that is less than a melting temperature of said enhanced boiling layer;

a boiling inlet for delivering liquid to said boiling passage;

a cooling inlet for delivering fluid to said cooling passage;

a boiling outlet for recovering vapor from said boiling passage; and

a cooling outlet for recovering fluid from said cooling passage.

2. The heat exchanger of claim 1, wherein the metal walls predominantly comprise aluminum.

3. The heat exchanger of claim 1, wherein said enhanced boiling layer includes between about 0.5 and about 1.5 wt- % silicon.

4. The heat exchanger of claim 1, wherein the highly proportioned aluminum alloy comprises 92 wt-% of the enhanced boiling layer and the eutectic alloy comprises 8 wt-% of the enhanced boiling layer.

5. The heat exchanger of claim 1, wherein said boiling side has a boiling heat transfer coefficient of above 10,000 BTU/hr/ft²°

F.

6. The heat exchanger of claim 1, wherein the eutectic alloy is 12 wt-% silicon and 88 wt-% aluminum.

7. A heat exchanger comprising:

a plurality of metal walls, each metal wall comprising two sides, a boiling side with an enhanced boiling layer comprising thermally conductive particles comprising a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminum and silicon integrally bonded together and metallurgically bonded to the boiling side and a cooling side, said thermally conductive particles comprising brazed alloy of a first metal and a second metal, said second metal alloying with said first metal to provide an alloy with a melting temperature that is lower than the melting temperature of said first metal, said boiling sides of said plurality of metal walls defining boiling passages and said cooling sides of said plurality of metal walls defining cooling passages and each of said plurality of metal walls further including a bonding surface;

a plurality of spacer bars each between pairs of said metal walls, each of said spacer bars having a bonding surface;

a layer of metal between each of said bonding surfaces of said metal walls and a bonding surface of an adjacent one of said plurality of spacer bars, said layer of metal comprising an alloy including said first metal and an elevated brazing temperature of said layer of metal is less than a melting temperature of said enhanced boiling layer;

a boiling inlet for delivering liquid to said boiling passage;

a cooling inlet for delivering fluid to said cooling passages;

a boiling outlet for recovering vapor from said boiling passages; and

a cooling outlet for recovering fluid from said cooling passages.

8. The heat exchanger of claim 7, wherein said layer of metal comprises an additional metal with a greater concentration of said additional metal than a concentration of said second metal in said enhanced boiling layer.

9. The heat exchanger of claim 7, wherein the second metal and the additional metal are silicon.

10. The heat exchanger of claim 7, wherein the enhanced boiling layer includes between 0.5 and 1.5 wt-% silicon.

11. The heat exchanger of claim 7, wherein the highly proportioned aluminum alloy comprises 92 wt-% of the enhanced boiling layer and the eutectic alloy comprises 8 wt-% of the enhanced boiling layer.

12. The heat exchanger of claim 7, wherein said enhanced boiling layer is porous and said thermally conductive particles are metallurgically bonded to the boiling side.

13. A heat exchanger comprising:

a plurality of metal walls, each metal wall comprising two sides, a cooling side and a boiling side with an enhanced boiling layer comprising thermally conductive particles, said thermally conductive particles including a highly proportioned aluminum alloy powder mixed with a eutectic alloy of aluminum and silicon, said thermally conductive particles being integrally bonded together and metallurgically bonded to the boiling side, said boiling side of said plurality of metal walls defining a boiling passage and said cooling side of said plurality of metal walls defining a cooling passage and each of said plurality of metal walls further including a bonding surface;

a spacer member for spacing metal walls from each other;

a layer of metal between said bonding surfaces of said metal walls and said spacer member in said heat exchanger, said layer of metal having a melting temperature that is less than a melting temperature of said enhanced boiling layer;

a boiling inlet for delivering liquid to said boiling passage;

a cooling inlet for delivering fluid to said cooling passage;

a boiling outlet for recovering vapor from said boiling passage; and

a cooling outlet for recovering fluid from said cooling passage.

14. The heat exchanger of claim 13, wherein said boiling side has a boiling heat transfer coefficient of above 10,000 BTU/hr/ft²°

F.