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 microchannel evaporator includes a plurality of microchannels. Each of the plurality of microchannels includes a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the microchannel evaporator. Each microchannel of the plurality of microchannels includes at least one bend along a length thereof.

A microchannel evaporator includes a plurality of microchannels. Each of the plurality of microchannels includes a first end and a second end. A first end-tank is coupled to each first end of the plurality of microchannels and a second end-tank is coupled to each second end of the plurality of microchannels. A second-fluid inlet is coupled to either the first end-tank or the second end-tank and configured to receive a fluid into the microchannel evaporator and a second-fluid outlet is coupled to either the first end-tank or the second end-tank and configured to expel the fluid from the microchannel evaporator. Each microchannel of the plurality of microchannels includes at least one bend along a length thereof.

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 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%.

Disclosed is an aluminum alloy brazing sheet including a core material, a brazing filler material provided on one surface of the core material and formed of an Al—Si based alloy, and a sacrificial anode material provided on the other surface of the core material, the brazing sheet having a thickness of less than 200 μm, wherein the core material includes more than 1.5% by mass and 2.5% or less by mass of Cu, and 0.5 to 2.0% by mass of Mn, with the balance being Al and inevitable impurities, wherein the sacrificial anode material includes 2.0 to 10.0% by mass of Zn, an Mg content in the sacrificial anode material being restricted to 0.10% or less by mass, with the balance being Al and inevitable impurities, and wherein each of the brazing filler material and the sacrificial anode material has a thickness thereof in a range of 15 to 50 μm, and the total of cladding rates of the brazing filler material and sacrificial anode material is 50% or less.

A syngas loop boiler includes a casing that surrounds a tube bundle, wherein the tube bundle includes a plurality of tubes. One end of each of the tubes is joined to a tube-sheet provided with corresponding tube-sheet inlet holes for inletting the syngas in the boiler, wherein each tube-sheet inlet hole is internally provided with at least a protective sleeve welded at both ends to corresponding surfaces of the tube-sheet inlet hole. Each tube-sheet inlet hole is provided with a first respective weld overlay placed at the inlet mouth of the tube-sheet inlet hole, so that a first end of each protective sleeve is welded to the first weld overlay. Each tube-sheet inlet hole is internally provided with at least a bore groove that contains a respective in-bore second weld overlay, so that the second end of the protective sleeve is welded to the in-bore second weld overlay. Each protective sleeve is thus welded at both ends to respective weld overlays, with the possibility of removal and re-installation without performing any post weld heat treatment.

A hydrophilic coating for use with a heat exchanger includes an insolubilizer configured to provide structure or support for the hydrophilic coating. The hydrophilic coating further includes a wetting agent configured to provide wettability for the hydrophilic coating. The hydrophilic coating further includes an antibacterial agent configured to eliminate at least a portion of bacteria that contacts the hydrophilic coating. The hydrophilic coating further includes an antifungal agent configured to eliminate at least a portion of fungi that contacts the hydrophilic coating, the antifungal agent being different than the antibacterial agent and the insolubilizer.

A hydrophilic coating for use with a heat exchanger includes an insolubilizer configured to provide structure or support for the hydrophilic coating. The hydrophilic coating further includes a wetting agent configured to provide wettability for the hydrophilic coating. The hydrophilic coating further includes an antibacterial agent configured to eliminate at least a portion of bacteria that contacts the hydrophilic coating. The hydrophilic coating further includes an antifungal agent configured to eliminate at least a portion of fungi that contacts the hydrophilic coating, the antifungal agent being different than the antibacterial agent and the insolubilizer.

A heat exchanger is provided that is operated in a cooling operation mode in which a region to be heat-exchanged is cooled by the heat exchanger or in a drying operation mode in which the heat exchanger is supplied with wind from a blowing fan. The heat exchanger includes a refrigerant pipe, a cooling fin coupled to the refrigerant pipe, and a hydrophilic coating coated on a surface of the refrigerant pipe or the cooling fin. The hydrophilic coating includes a first type transition metal oxide which becomes acidic by reacting with moisture formed on the refrigerant pipe or the cooling fin to have antimicrobial activity when the heat exchanger is operated in the cooling operation mode, and a second type transition metal oxide or a post-transition metal oxide which has antimicrobial activity when the heat exchanger is operated in the drying operation mode.