An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using flux includes a core material of aluminum or aluminum alloy, and a brazing material of aluminum alloy including Si of 4.0 mass % to 13.0 mass % and cladding one side surface or both side surfaces of the core material. One or both of the core material and the brazing material includes any one or two or more types of X atoms (X is Mg, Li, Be, Ca, Ce, La, Y, and Zr). The aluminum alloy brazing sheet is a brazing sheet in which oxide particles including the X atoms and having a volume change ratio of 0.99 or lower with respect to an oxide film before brazing heating are formed on a surface thereof, by brazing heating.

An aluminum brazing sheet for flux-free brazing having a multilayer structure of two or more layers including at least one core material layer and one brazing material layer, wherein the brazing material layer is positioned on one or both sides of the core material layer and on an outermost surface of the brazing sheet. The brazing material layer is made of an Al—Si—Mg—X brazing material containing: in mass%, 0.05 to 2.0% of Mg, and 2.0 to 14.0% of Si, and further containing one or more of 0.01 to 0.3% of Bi, Ga, Sn, In and Pb, a total amount of Bi, Ga, Sn, In and Pb being 0.5% or less. X indicates one or more of Bi, Ga, Sn, In and Pb.

Disclosed is a microchannel heat exchanger comprising a primary core including a first header and a second header and a secondary core including a first auxiliary header and a second auxiliary header, further comprising a first header interconnect extending between the first header and the first auxiliary header and having a first interconnect fluid passage extending therethrough; and a second header interconnect extending between the second auxiliary header and the second header and having a second interconnect fluid passage extending therethrough.

A brazing material for brazing aluminum or an aluminum alloy includes fluoride-based flux, a solidifying agent, and a coating film uniformity agent, and is solid at 25° C.

A heat exchanger brazing fixture including a baseplate including a first surface and a second surface located opposite the first surface and a first post including a first end and a second end located opposite the first end. The first post is operably associated with the first surface of the baseplate at the first end. The A heat exchanger brazing fixture further including a top plate operably connected to the first post and separated from the first surface of the baseplate by a selected distance. The top plate being configured to move in a first direction along the first post when a heat exchanger resting upon the first surface of the baseplate expands during a brazing process.

A heat exchanger includes: a header that extends in a first direction; and a plurality of heat transfer tubes that extend in a second direction crossing the first direction, each of which has one end connected to the header, and that are arranged in the first direction at intervals. The header includes: a header body having a tubular shape, a first member through which the one end of each of the heat transfer tubes extends, and a second member positioned between the header body and the first member in the second direction. The second member includes: a base portion that extends in the first direction, and a plurality of protruding portions that extend from the base portion toward the first member in the second direction.

A heat exchanger, includes a heat exchange pipe unit and a fin unit, the heat exchange pipe unit includes a refrigerant input pipe, a heat exchange pipe assembly and a refrigerant output pipe; the refrigerant input pipe is connected to one end of the heat exchange pipe assembly; the refrigerant output pipe is connected to the other end of the heat exchange pipe assembly; the fin unit is fixedly arranged outside of the heat exchange pipe assembly; the heat exchange pipe assembly and the fin unit are made of aluminum alloy; and the corrosion potential of the aluminum alloy which forms at least a part of the heat exchange pipe assembly is greater than the corrosion potential of the aluminum alloy which forms the remaining part of the heat exchange pipe assembly.

A water heater includes an outer casing defining a longitudinal axis, an axial direction being defined as extending along the longitudinal axis. The water heater further includes a combustor for production of hot flue gases, a primary heat exchanger including a tube positioned within the outer casing, and a secondary heat exchanger including a plurality of plates coupled together by brazing to form a brazed plate heat exchanger. The secondary heat exchanger includes a first set of passages defined between the plates, and a second set of passages defined between the plates and alternating with the first set of passages in the axial direction. The primary and secondary heat exchangers are in fluid communication such that the flue gases flow through the second set of passages before being exhausted, and water to be heated flows through the first set of passages to a delivery point for use upon demand.

A method of making a heat exchanger that includes sealing tubes to header slots and brazing the tubes to the header slots. The method further includes coupling a cover to the header to cover a liquid-side surface of the header and to cover ends of the tubes, and applying flux to an air-side surface of the header and to the tubes. Coupling the cover to the header is performed after sealing the tubes to the header slots and coupling the cover to the header is performed before applying flux to the air-side surface of the header and to the tubes. Applying flux is performed before brazing each of the tubes to the header slots and sealing each of the tubes to the header slot includes sealing a perimeter of each of the tubes to the header slot.

The invention describes methods of welding onto laminated devices using a low temperature welding process. Also described are laminated devices with welds that do not disrupt a brazed core block of sheets in the laminated devices. Novel laminated devices with welded features for servicing the devices are also described.