Abstract Potential difficulties with corrosion resistance in air cooled condensers utilizing aluminum fins are avoided by using fin and tube constructions made by a method which includes the steps of providing a flattened tube (50) of ferrous material (80) and having an exterior coating (82) predominantly of aluminum; providing at least one serpentine fin (56) of aluminum (86) and clad with a predominantly aluminum braze cladding (88); assembling (102) the fin (56) to the flattened tube (50); applying (94), (100), (104), a brazing flux to at least one of the fin (56) and the tube (50); raising (106) the temperature of the assembly to a level sufficient to at least partially melt the braze cladding (88); and maintaining the temperature for a sufficient Period of time to achieve a brazed joint (60) between the fin (56) and the tube (50) but a time insufficient to convert the coating (82) and the cladding (88) to ferrous-aluminum intermetallic compound or intermediate phase.
A fin and tube assembly for use in a heat exchanger and consisting essentially of: a steel tube provided with an external coating of aluminum; and at least one aluminum fin having aluminum braze cladding in contact with and brazed to said tube; said assembly being characterized by the absence of any appreciable exposed layer of ferrous-aluminum intermetallic compound or intermediate phase on the exterior of said tube in the area of said fin.
Claim 2
Dependent Claim
74 words
A fin and tube assembly for use in a heat exchanger and consisting essentially of: a steel tube provided with an external coating of aluminum; and at least one aluminum fin having aluminum braze cladding in contact with and brazed to said tube; said assembly being characterized by the absence of any appreciable exposed layer of ferrous-aluminum intermetallic compound or intermediate phase on the exterior of said tube in the area of said fin.
Claim 3
Dependent Claim
17 words
The fin and tube assembly of claim 1 wherein both said coating and said cladding include silicon.
Claim 4
Dependent Claim
62 words
A power plant including a steam turbine, a generator connected to said steam turbine to be driven thereby, a condensate return line for providing condensed exhaust steam from said turbine for make up to a heater for producing steam and a heat exchanger operatively associated with said line and comprised of a plurality of the fin and tube assemblies of claim 10.
Claim 5
Dependent Claim
18 words
The power plant of claim 3 wherein said tubes are elongated and said assemblies are in side-by-side relation.
Claim 6
Dependent Claim
27 words
The power plant of claim 3 wherein said line is in fluid communication with the turbine via interior of the tubes of each fin and tube assembly.
Claim 7
Dependent Claim
40 words
The power plant of claim 3 wherein said line is in fluid communication with the turbine via a second heat exchanger, and means for circulating a heat exchange fluid through the interiors of said tubes and said second heat exchanger.