Multilayered brazing sheet material including an aluminium core alloy layer having a first brazing clad layer material on one face of the core layer and a second brazing clad layer material on the other face of the core material, and an inter-layer between the core layer and the first brazing clad layer material, wherein the core layer is 3xxx-series aluminium alloy having, in wt. %, up to 0.4% Si, up to 0.5% Fe, 0.4% to 0.75% Cu, 0.6% to 1.1% Mn, up to 0.04% Mg, up to 0.2% Cr, up to 0.25% Zr, up to 0.2% Ti, up to 0.15% Zn, balance aluminium and impurities, wherein the first brazing layer and the second brazing layer are 4xxx-series aluminium alloy having 7% to 14% Si and up to 2% Mg, balance aluminium and impurities, and wherein the inter-layer is aluminium alloy of the 1xxx-series alloys.

A clad material includes a core material, a first skin material covering one side of the core material, and a second skin material covering the other side of the core material. The clad material is brazed in a state in which the first and second skin materials overlap each other. The core material is made of an Al alloy containing Mn (0.6 to 1.5 mass %), Ti (0.05 to 0.25 mass %), Cu (less than 0.05 mass %), Zn (less than 0.05 mass %), Fe (0.2 mass % or less), and Si (0.45 mass % or less) (balance: Al and unavoidable impurities). The first skin material is made of an Al alloy containing Si (6.8 to 11.0 mass %) and Zn (0.05 mass % or less) (balance: Al and unavoidable impurities). The second skin material is made of an Al alloy containing Si (4.0 to 6.0 mass %) and Cu (0.5 to 1.0 mass %) (balance: Al and unavoidable impurities).

A brazed heat exchanger includes plates that are stacked or nested to define flow channels for multiple media. Inserts are arranged within at least some of the flow channels. Two different braze alloys having compositions based on different metals are used to form braze joints between the plates and the inserts. In some cases, a copper-based braze alloy is used for joints corresponding to flow channels for one of the media in order to provide high pressure-resisting strength to those flow channels, while an iron-based braze alloy is used for joints corresponding to flow channels for another of the media where dissolved copper is undesirable.

A surface treatment method for aluminum heat exchangers including (a) a step wherein a chemical conversion coating film is formed on the surface of an aluminum heat exchanger by subjecting the aluminum heat exchanger to chemical conversion using a chemical conversion agent; (b) a step wherein the aluminum heat exchanger, the surface of which has been provided with a chemical conversion coating film in step (a), is brought into contact with a hydrophilizing agent that contains a hydrophilic resin; and (c) a step wherein a hydrophilized coating film is formed on the surface of the aluminum heat exchanger by baking the aluminum heat exchanger, which has been subjected to a contact treatment in step (b). The chemical conversion agent used in step (a) contains zirconium and/or titanium in an amount of 5-5,000 ppm by mass in total, vanadium in an amount of 10-1,000 ppm by mass and a metal stabilizer in an amount of 5-5,000 ppm by mass. In addition, the chemical conversion agent used in step (a) has a pH of 2-6.

A brazed heat exchanger, for example a heat exchanger to be used in an air-conditioning system, preferably as a condenser, includes flat tubes extending between a pair of header tubes and fins arranged between the flat tubes. The components are produced from aluminum alloys, and are brazed together using an AlSi braze alloy. The aluminum alloys have a zinc content of no greater than 0.5% before brazing, and zinc from the aluminum alloys diffuses into the braze joints to result in braze joints having an average zinc content of no greater than 0.1%.

A tube used in a heat exchanger, wherein a tube body includes a curved end portion, a pair of parallel portions, a pair of inclination portions, and a fixed portion in which a long end part extending from one of the pair of inclination portions is bent to hold therebetween a short end part extending from the other of the pair of inclination portions, and the tube is a pipe member having a flattened shape in cross-section. Poor brazing is reduced by making the inclination angle of at least part of the other inclination portion with respect to the flat plate portion larger than that of the one inclination portion.

The invention relates to a brazable three-layered aluminum composite material having at least three layers with at least two different aluminum alloys, whereby an inner layer of the at least three layers is an aluminum brazing layer made from an aluminum brazing alloy, the other layers are configured as covering layers and include at least one further aluminum alloy, wherein the at least one further aluminum alloy has a higher solidus temperature than the liquidus temperature of the aluminum brazing alloy. The individual covering layers have a thickness which exceeds the thickness of the aluminum brazing layer by at least a factor of 1.5, preferably by a factor of 5. The brazable aluminum composite material is simply structured, has good brazing properties for the production of butt-joint brazing connections, significantly reduces the risk of a ‘burning through’ of brazed-on components and provides sufficient mechanical properties.

Methods for improving heat transfer at the interface between the internal reactor wall and mesh media containing microfibrous entrapped catalysts (MFECs) and/or microfibrous entrapped sorbents (MFESs) are described herein. Improved (e.g., more rapid) heat transfer can be achieved using a variety of approaches including increasing the contacting area of the interface between the mesh media and the reactor wall so that more contacting points are formed, enhancing the contacting efficiency at the contacting points between the mesh media and the reactor wall, increasing the number of contact points between the mesh media and the reactor wall using fine fibers, and combinations thereof.

A pre-flux coating for the manufacturing of heat exchanger components of aluminum, wherein the coating comprises a combination of fluxes in the form of potassium aluminum fluoride K.sub.1-3AlF.sub.4-6, potassium trifluoro zincate, KZnF.sub.3, lithium aluminum fluoride Li.sub.3AlF.sub.6, a filler material in the form of metallic Si particles, Al—Si particles and/or potassium fluoro silicate K.sub.2SiF.sub.6, an additive in the form of aluminum oxide and at least one other oxide selected from the group consisting of zinc oxide, titanium oxide and cerium oxide forming a post braze ceramic layer, and a solvent and a binder containing at least 10% by weight of a synthetic resin which is based, as its main constituent, on a methacrylate homopolymer or a methacrylate copolymer.

A hollow aluminum structure that will be brazed includes at least one brazing sheet having a filler metal layer clad onto a core layer. The core layer is composed of aluminum or an aluminum alloy containing less than 0.2 mass % Mg. The filler metal layer is composed of an aluminum alloy that contains Si: 4.0-13.0 mass % and Bi: 0.01-0.3 mass %, and further contains Li: 0.004-0.08 mass % and/or Be: 0.006-0.12 mass %, the filler metal layer containing less than 0.1 mass % Mg. The hollow aluminum structure is assembled such that the filler metal layer is present at locations that will form both an interior-facing brazed joint and an exterior-facing brazed joint. Then, flux is applied onto the filler metal layer at the location that will form the exterior brazed joint, and the hollow aluminum structure heated in an inert gas atmosphere to form the interior brazed joint and the exterior brazed joint.