Aluminum alloy tube and fin assembly for heat exchangers having improved corrosion resistance after brazing

• US 7,781,071 B2
• Filed: 12/22/2003
• Issued: 08/24/2010
• Est. Priority Date: 12/23/2002
• Status: Active Grant

• Current Assignee: Alcan Incorporated (Alcan)
• Original Assignee: Alcan Incorporated (Alcan)
• Inventors: Gray, Alan, Ramanan, Thiagarajan, Parson, Nicholas Charles, Marois, Pierre Henri
• Primary Examiner(s): Austin; Aaron
• Application Number:
  US10/539,722
• Publication Number:
  US 20060231170A1
• Time in Patent Office: 2,437 Days
• Field of Search: None
• US Class Current: 428/654
• CPC Class Codes: C22C 21/00 Alloys based on aluminium
• CPC Class Codes: C22C 21/10 with zinc as the next major constituent
• CPC Class Codes: C22F 1/04 of aluminium or alloys based thereon
• CPC Class Codes: F28F 21/084 from aluminium or aluminium alloys
• CPC Class Codes: Y10S 165/905 Materials of manufacture
• CPC Class Codes: Y10T 428/12764 Next to Al-base component

Abstract

The present invention provides extruded tubes for heat exchangers having improved corrosion resistance when used alone and when part of a brazed heat exchanger assembly with compatible finstock. The tubes are formed from a first aluminum alloy containing 0.4 to 1.1% by weight manganese, up to 0.01% by weight copper, up to 0.05% by weight zinc, up to 0.2% by weight iron, up to 0.2% by weight silicon, up to 0.01% by weight nickel, up to 0.05% by weight titanium and the balance aluminum and incidental impurities. The fins are formed from a second aluminum alloy containing 0.9 to 1.5% by weight manganese or an alloy of the AA3003 type, this second aluminum alloy further containing at least 0.5% by weight zinc.

Claims

1. A brazed heat exchanger assembly comprising extruded heat exchanger tubes joined to heat exchanger fins;

wherein said heat exchanger tubes are formed of a first aluminum alloy comprising 0.4 to 1.1% percent by weight manganese, up to 0.01% by weight copper, up to 0.05% by weight zinc, up to 0.2% by weight iron, up to 0.2% by weight silicon, up to 0.01% by weight nickel, up to 0.05% by weight titanium, and a balance of aluminum and incidental impurities;

wherein said heat exchanger fins are formed of a second aluminum alloy comprising 0.9 to 1.5% by weight manganese and at least 0.5% by weight zinc;

wherein the heat exchanger tubes exhibit good self corrosion protection and the heat exchanger fins are galvanically sacrificial relative to the heat exchanger tubes; and

wherein the manganese weight percent of the first aluminum alloy is related to the manganese weight percent of the second aluminum alloy by the formula

Mn_tube(wt %)>

Mn_fin(wt %)−

0.8 wt %

where Mn_tube is the manganese weight percent of the first aluminum alloy and Mn_fin is the manganese weight percent of the second aluminum alloy.

2. A brazed heat exchanger assembly according to claim 1, wherein the second aluminum alloy further comprises less than 0.05% by weight copper.

3. A brazed heat exchanger assembly according to claim 1, where a galvanic current from fin to tube is greater than +0.05 microamps per square centimeter.

4. A brazed heat exchanger assembly according to claim 1, wherein the manganese weight percent of the first aluminum alloy is between 0.6 and 1.19%.

5. A brazed heat exchanger assembly according to claim 4 where the manganese weight percent of the first aluminum alloy is between 0.9 and 1.1%.

6. A brazed heat exchanger assembly according to claim 1, wherein the second aluminum alloy is an AA3003 alloy having added zinc to produce a zinc content of said at least 0.5% by weight.