Method for joining an aluminium alloy fin to a steel tube and heat exchanger made therefrom

Abstract

The invention relates to a method for joining an aluminium rib to a steel tube, comprising the steps of (a) providing a first component in the form of a steel tube having an inner surface and an outer surface, and wherein at least the outer surface has a surface coating in the form of a braze-promoting layer comprising one or more metals selected from the group comprising nickel, cobalt, and palladium; (b) providing a second component forming a fin in the form of an aluminium brazing sheet, the aluminium brazing sheet comprising of an aluminium alloy core upon which on at least one side filler alloy is clad, and wherein the filler alloy has a composition comprising, in wt.%: Si 5-15%, Mg 0.03-1%, one or more elements selected from the group consisting of: (Bi 0.02-0.5, Pb 0.03-0.4, and Sb 0.03-0.4, and the sum of these elements being 0.5% or less), the balance aluminium; (c) bringing the first component and the second component into contact to form an assembly of components and whereby the braze-promoting layer is facing the filler alloy clad layer of the brazing sheet; (d) heating and subsequently holding the assembly of components in an inert gas atmosphere and without applying flux at a brazing temperature in the range between 550°C and 615°C to form a permanent bond occurring on at least one contact point of these components; and (e)cooling the brazed assembly of components.

Description

technical field [0001] The present invention relates to a method of joining an aluminum alloy rib or fin to a steel tube or pipe. Furthermore, the invention relates to heat exchangers comprising units or modules produced according to said method, in particular heat exchangers for industrial installations and power plants. Background technique [0002] Heat exchangers of the related type generally have distribution pipes that are at least partially equipped with cooling fins on their outer surfaces, as described, for example, in European patent application EP-1553379-A1. Heat exchange occurs when a first medium (or fluid) flowing through a tube and cooling it dissipates its heat to cooling fins surrounding the tube with a second medium or fluid flowing around it, For example in particular cooling air or cooling gas, the heat is dissipated to the second medium. It will be apparent to those skilled in the art that reverse heat exchange is also possible. [0003] If the first...

AI Technical Summary

Problems solved by technology

However, roll bonding aluminum sheets to steel is a complex and expensive process

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