Abstract: A method of making a solar energy collector where the absorber plate, selective surface, and protective outer skin of the collector are formed by spraying molten metal particles onto a substrate and building a coating of metal up to a desired thickness. This process allows greater flexibility in permitting a greater choice of materials and geometric shapes to be used for manufacturing the collector. The process may also be used to create the individual components of the collector, i.e., body, absorber plate, or selective surface as well as a storage tank.

Abstract: A method for production of a heat exchanger is disclosed, where a powder flux is applied in a process of soldering a heat exchanger core of aluminum. An annular groove is formed in a seat plate. Measures are taken for preventing wetting of the annular groove of the seat plate when sprayed with the water on the preassembled core, such that a non-corrosive flux would not adhere to the annular groove of the seat plate. Water is sprayed in the form of a mist on a preassembled heat exchanger core through plurality of spray nozzles. The annular grooves of the seat plates are thoroughly dried after the application of water for attaining a perfect absence of residual non-corrosive flux in the annular grooves of the seat plates. A non-corrosive flux powder is sprayed onto the preassembled heat exchanger core of aluminum with a powder spray gun. The non-corrosive flux is caused to adhere fast to the portion wetted with the water.

Abstract: An aluminum material for brazing, comprising a core made of aluminum or an aluminum alloy, and a layer coated on the surface of the core. The layer is made of zinc or an alloy of zinc-and-aluminum and a brazing alloy having a melting point which is lower than that of the core by a predetermined value. The zinc or the alloy of zinc-and-aluminum and the brazing alloy have different melting points. Also disclosed are a method of manufacturing an aluminum material for brazing and a method of manufacturing an aluminum alloy heat exchanger by use of the Al material for brazing.

Abstract: An improved copper radiator for motor cars comprising a plurality of tubes adapted for the flow of a heat-exchanging medium therethrough, fins bonded directly with solder to said tubes to form a copper core and wherein said core is bonded with solder to at least one seat plate, the improvement in that the surface of the fins of said copper radiator has an oxidized layer of a thickness of not more than 1200 .ANG..

Abstract: To permit high-temperature differential cross flow of an initially cool, heat absorbing medium and an initially hot, heat releasing medium, with temperature differences in the order of 1000.degree. and higher, and to prevent localized thermal overload, the heat exchanger is a two-stage heat exchanger, with plate packages (5, 6) which are serially passed by the media, typically gaseous media. The first package (5) forms a preheater stage and the second package (6) forms a final heater stage. Connecting ducts (9, 10) are provided and so arranged that the initially hot fluid medium is conducted through flow channels in the second heater stage which receives heat absorbing medium which has already passed through the preheater stage, so that it has already been preheated, thereby reducing the temperature difference between the preheated heat absorbing medium and the initially hot, heat releasing medium.

Abstract: A fitting for a two flat tube serpentine heat exchanger having high burst pressure comprises a header plate with two slots for receiving the flat tubing and a cover plate with a port, a nipple protruding from the port, and a recess surrounding the port and extending over the slots to provide communication between the port and the slots. The plates are formed by extrusion with the appropriate apertures, cut to the desired thickness and the recess is milled out, or the plates and apertures are stamped from sheet rock. The plates are welded together at their common periphery or brazed together at their margins outboard of the recess.

Abstract: A soldering structure of a tubular material for soldering one end portion of a tubular material to an auxiliary plate with a soldering material coated thereto, wherein the plane auxiliary plate is formed therein with a communicating hole for allowing the tubular material to be inserted therein, one end portion of the tubular material is inserted into the communicating hole and temporarily secured to the auxiliary plate through a deformation of the auxiliary plate at the end portion of the tubular material or the peripheral area of the communicating hole before soldering, thereby to close one end of a space between the peripheral surface of the tubular material and the inner wall of the communicating hole, the space allowing the soldering material melted to be pooled therein during soldering, and the tubular material and auxiliary plate being soldered when the melted soldering material pooled in the space is hardened.

Abstract: An inner tube tube an outer surface of which is machined to define regerative coolant grooves for flowing a coolant to cool a combustor is split at a throat into upper and lower portions which in turn are fitted into an outer tube fabricated as a unitary structure. The upper and lower inner tube portions and the inner and outer tubes are integrally joined together.

Abstract: A method for producing corrosion resistance heat exchangers having a plurality of aluminum tubular elements and fin members, the method comprising immersing the tubular elements in a bath with passing an electric current so that the surfaces thereof are covered with zinc layers of 0.3 .mu.m or more in thickness; combining the zinc plated tubular elements with fin members covered with a brazing sheet so that a core is provisionally formed; painting the provisional core with a non-corrosive flux; and placing the provisional core in a furnace to braze the fin members to the tubular elements, and also to enable the zinc layers to diffuse over the surfaces of the tubular elements.

Abstract: Assembly device of tubes in low carbon ferritic stainless steel having 17 to 18.5% by weight of chromium on a tube-plate of carbon steel. It includes at least one overlay of low carbon steel on the surface of the tube-plate opposite the plurality of tubes, of such thickness that the ends of the tubes are located at an intermediate level of the overlay, and weld beads between the ends of the tubes and the overlay.

Abstract: In a compact heat sink the heat exchange surface consists of metal screen which has been crimped in a wave-like form and then brazed to a metal mounting base. The braze is along the trough of the wave where the mesh contacts the base. The base serves as a carrier for attaching the wire mesh to the object requiring heat transfer. The primary application of this form is heat sinking small electronic package such as "flat-packs" etc. An advantage of the design is that it makes a package which is physically compatible with miniature, low static pressure fans. A secondary form described in the disclosure is an air-to-air heat exchanger in which two crimped screens are attached to the base- one on either side. This application is useful for removing heat from a totally enclosed package. In this case the mounting base is larger than the crimped screen to allow for a flange of clear metal around the perimeter of the screen such that it may be attached to a prepared opening in the sealed package.

Abstract: A method for replacing a damaged or defective section of a length of original piping or tubing located within a structrue such as the turbine of a jet engine wherein access to the tubing is limited, and replacing such damaged section with a new section of tubing comprises inserting a cutter mounted at one end of a flexible shaft into the interior of the original tubing and rotating the shaft to cut out and remove the damaged section of tubing leaving at least one stub section of original tubing. The stub sections of original tubing are then prepared for welding or brazing to a section of replacement tubing with a series of tools each mounted to an elongated shaft. These tools include a chamfering tool, a deburring tool, and a polishing tool.

Abstract: A method of producing a heat exchanger comprising abutting a tube made of an aluminum material and fins made of an aluminum material, applying to the resulting abutments a flux containing zinc halide, and thereafter conducting a reaction soldering in an inert gas atmosphere. The assembled tube and fins applied with the flux may be moved into a position to enhance the formation if zinc deposited by the reaction soldering during the drying step of the flux. The heat exchanger produced by this method has a thick and uniform Zn coating at the joints with good mechanical strength and surface conditions.

Abstract: A method of treating a heat exchanger made of aluminum or an aluminum alloy comprising applying onto the surface of the aluminum heat exchanger a noncorrosive flux having a flux core with an outer coating of zinc or a zinc alloy formed by vacuum vapor deposition or ion plating, and then heating the resulting heat exchanger to effect brazing. A diffused zinc layer forms on the surface of the heat exchanger and protects it from corrosion, in particular, from electrolytic corrosion.

Abstract: This is a process which provides the first essentially continuous high tin flow soldering method for attaching copper-based fins to non-copper-based tubing. This invention avoids sludge buildup in the reservoir and generally avoids lead carbonate formation when the heat produced having a braze-like joint with eta phase layers exchanger is in service. In addition, a novel structure is adjacent to copper-containing surfaces. The invention utilizes an essentially lead-free, high tin solder cascade onto a preferably cool tube, genrally with a limited time of contact between the liquid solder and the tube, and with a combination air quench and wipe to remove excess solder and solidify the remaining solder. Thus a braze-like joint is achieved having better heat conduction and closer thermal expansion match. This finned heat exchanger tubing is generally useful for liquid to gas-type heat exchangers.

Abstract: A process of attachment of at least one rib on a pipe with a thin wall which comprises cutting a hole in the rib that corresponds closely to the outer diameter of the pipe; locating the rib on the outer surface of the pipe; pressurizing the interior of the pipe with a pressure sufficient to force the outer surface of the pipe into close relationship with the inner contour of the rib during or shortly before reaching the soldering temperature; attaching the rib to the pipe by soldering; and selecting the materials for the rib and pipe so that the linear thermal expansion coefficients allow a smaller gap between the pipe and the rib during soldering than when the pipe and rib are at room temperature.

Abstract: An improved heat exchanger is shown for indirect heat exchange between two fluid media. The heat exchanger has thin metallic walls and a multitude of convoluted or tortuous shaped internal flow passages to increase the effective contact time during which heat is transferred between the media. The heat exchanger is particularly suitable for heat exchange between fluids having low differential temperatures or specific heats, due to the thin wall structure, the elongated tortuous internal flow path created by the core structure and the absence of welds, soldering or other thick areas which tend to inhibit heat transfer due to their relatively greater mass. The heat exchanger is produced by a novel technique. A support matrix is assembled from a plurality of low melting point forms, each of which has angled internal passages. The passages of each form are positioned in register with the passages of adjacent forms.

Abstract: A panelizing machine assembly for clamping elongated structures such as tubes at spaced intervals and then welding the structures. The machine includes an elongated main frame having connecting cross members, and provided with at least two bed plates each having a plurality of notches on their upper side, and at least two carriage structures which are self-supporting and longitudinally movable on the main frame. Each carriage is equipped with at least one contoured clamping plate which is vertically movable by pressurized piston means and have notches on their lower sides adapted for clamping the tubes onto the bed plates prior to the welding operations. Each carriage is independently movable along the main frame on rollers engaging rails attached to the elongated frame, and carriage movement is electrically controlled by photoelectric cells and brakes for accurate positioning, and operate in cooperation with a welding robot attached to the upper part of the central movable carriage.

Abstract: A method for the production of a heat exchanger having a core part thereof formed by joining a tube of aluminum material and heat-transfer fins of aluminum material with a brazing material, which method is characterized by effecting said brazing by the use of a flux obtained by suspending a potassium fluoroaluminate complex in an aqueous solution of a pigment-forming water-soluble compound.

Abstract: An improved copper radiator for motor cars comprising a plurality of tubes adapted for the flow of a heat-exchanging medium therethrough, fins bonded directly with solder to said tubes to form a copper core and wherein said core is bonded with solder to at least one seat plate, the improvement in that the surface of the fins of said copper radiator has an oxidized layer of a thickness of not more than 1200 .ANG..

Abstract: A catalytic converter includes a metal honeycomb catalyst support which is anchored in a canister so that it cannot telescope or blow out. The honeycomb catalyst support is made by folding a strip of metal back and forth upon itself. The lines of folding are inclined to the perpendicular to the axis of the strip. The repeating sequence of the inclinations is left, right, right, left, etc. Folding the strip in this manner produces a honeycomb that has a taper in both of two directions so that it can be anchored in the canister. The canister has a taper which coincides with the taper of the honeycomb. The invention also includes a method and apparatus for making crease lines on the strip, so that the strip can be folded.

Abstract: An air conditioner condenser manifold uses a tube having a flat side and a semi-oval cross-sectional shape, with holes pierced into the flat side of the tube without removing any material from the tube. The material of the flat side of the tube within an indentation around each of the holes is formed into a cylindrical collar recessed into the tube and having an inside axial length longer than the unpierced thickness of the tube. The ends of smaller tubes are bonded into each of the collars so that bonding material is disposed in the indentations around the holes.

Abstract: Fluxless joining of aluminum members, one of which is provided wih a coating of zinc solder, includes preheating the assembled members to a temperature above the melting point of the solder coating and applying a multistep vibration to the assembled members at elevated temperature. A heat exchanging section has a core of spaced hollow aluminum shapes interconnected by thin aluminum fins extending through the zinc coating layer and having direct contact with the aluminum shapes.

Abstract: A new and improved automotive heat exchanger and a method of assembling tubes in a header of a heat exchanger comprising, shaping the ends of non-circular cross section tubes into a substantially circular cross section, forming collared openings of substantially circular cross section in a header wall, inserting the tube ends into the openings, welding the tube ends to the collars, and bonding the tubes to the header wall.

Abstract: An improved heat exchanger assembly is disclosed and has a wall composed of a heat transmissive material and a plurality of sections of spaced-apart elongated fluid conduits also composed of a heat transmissive material disposed on one side of the wall for conveying a heat transfer fluid therethrough. The assembly includes an elongated filler member, which either has a solid outer surface or is a wire mesh structure, and which extends longitudinally through the space between at least one adjacent pair of the spaced-apart elongated fluid conduits or conduit sections. The elongated filler member is also composed of a heat transmissive material and at least in part spaced from the fluid conduit or conduit sections, thus defining at least one opening providing communication into the space between the adjacent pair of fluid conduits.

Abstract: When the free marginal portions 42 are telescoped within the confines of the peripheral flange 36 preparatory to the soldering operation, inward pressure on the end tank 38 usually is maintained during the soldering operation. Of course, the soldering operation involves the application of heat to both the peripheral flange 36 and the peripheral side wall 40. This sometimes will cause the free marginal portion 42 of the peripheral side wall 40 to deform inwardly away from the peripheral flange 36, thus leaving excessive spacing between the free marginal portion 42 and the peripheral flange 36. In order to avoid this condition, raised dimples 44 are formed in the header plate 34 along the peripheral flange 36 and spaced slightly inward from the latter a distance equal to the thickness of the peripheral side wall 40.

Abstract: A sealable multimetallic sleeve for a rapid repair of a degraded tube caused by a detrimental chemical attack on the outside surface of the tube within and in a vicinity of a tube sheet in a steam generator, and the method for sealably inserting the sleeve in the degraded tube spanning the region of the degradation. The sleeve includes an inner member with equivalent mechanical properties of the degraded tube and an outer member metallurgically bonded to the inner member and resistive to caustic intergranular chemical attack causing tube degradation. The sleeve has an expanded portion at one end for positioning in the tube within the tube sheet and a multiplicity of grooves in and adjacent to the other end of the sleeve and braze material contained in the grooves.

Abstract: A method of producing a lightweight and corrosion-resistant heat exchanger is disclosed. An aluminum tube with a plurality of passage bores therein is formed by extrusion. A layer of a brazing material comprising an aluminum alloy having an electrode potential value lower than that of the tube material is formed on the tube surface with the aid of a non-corrosive flux. The tube is bent into a zigzag winding form so as to have a plurality of substantially parallel runs. Corrugated fin members of aluminum or aluminum alloy are placed between respective adjacent runs of the tube. The tube and the fin members are heated together up to the melting point of the brazing material so that they are bonded together by the brazing material to form the heat exchanger.

Abstract: A heat exchanger core having a tube of aluminum material and heat transfer fins of aluminum material joined to each other with a brazing filler, which has at least part of the surface thereof coated with an inorganic sintered layer incorporating therein a pigment-containing phase of the two complexes of potassium hexafluoroaluminate and potassium tetrafluoroaluminate.

Abstract: The reinforcements in a radiator core assembly are perforated so as to form a shear zone in the legs thereof that maintain rigidity in the reinforcements for stacking and brazing and can be readily sheared thereafter.

Abstract: An aluminum alloy including magnesium can be joined by brazing even when flux made of potassium fluoaluminates is employed. The aluminum alloy including magnesium is heated in a vacuum, so that magnesium in the aluminum alloy evaporates from the surface of the aluminum alloy. The weight ratio of magnesium at the surface of the aluminum alloy can be reduced to less than 0.5 as a result of the heating step. The aluminum alloy treated by this operation is, thereafter covered with brazing material and clad with flux. After that, the aluminum alloy is heated in a furnace in order to melt the brazing material.

Abstract: A tube having a plurality of hydraulically parallel fluid passages for use in a heat exchanger can be made by forming an elongated, undulating insert and disposing the same within a flattened tube. A noncorrosive brazing flux is adhered to at least one of the interior of the tube and the crests on the undulating insert. Braze alloy is also located at the interface of the crests of the insert and the interior wall of the tube. Thereafter, the insert is located within the tube without disturbing the flux and the tube deformed along its length to bring the interior of the tube into contact with the crests on the insert. The assembled tube and insert construction is then heated to braze joints between the interior wall of the tube and the crests of the insert along the entire length of the latter.

Abstract: In production of a serpentine-type aluminum heat exchanger having an aluminum flat tube with a plurality of fluid passageways and aluminum header pipes connected to opposite ends of the flat tube, flat sleeves with outer end flanges of aluminum alloy brazing filler metal are fitted on the opposite end portions of the flat tube while the end flanges being in contact with outer surfaces of the header pipes. The sleeves and end flanges are melted by heating so that the header pipes are brazed to the flat tube.

Abstract: A method is set forth for forming a unitary structure having a plurality of deformable foils having first and second sides stacked one upon another with the first sides facing in one direction and the second sides in an opposite direction, each of the foils having an undulating cross-section, adjacent of the foils having their undulations orthogonal to one another and every other one of the foils having parallel orientations. The method comprises positioning a first plurality of parallel rods against the first side of a respective one of the foils and positioning a second plurality of parallel rods against the second side of the same foil with the rods of the second plurality of rods between and parallel to the rods of the first plurality of rods. Thereafter the aforementioned steps are repeated with each next adjacent foil having the rods defining the undulating cross-section thereof at a non-zero angle to the rods of the next adjacent foil.

Abstract: A heat exchanger and a method of manufacturing a heat exchanger by brazing metal members mainly made of Al or Al alloy is disclosed. The heat exchanger has a plurality of brazed metal members, at least one of the brazed metal members being made of brazing sheet clad with a brazing material. The brazed portions of the metal members or the whole surface of the heat exchanger are coated with a corrosion-resistant fluoride flux consisting essentially of 25-40% KF, 38-54% AlF3 and 3-30% ZnF2 by weight which forms a corrosion-inhibiting metallic film.

Abstract: This is an article and process which provide the first essentially continuous high tin flow soldering method for attaching copper based fins to copper based tubing. This invention avoids sludge buildup in the reservoir and generally avoids lead carbonate formation when the heat exchanger is in service. In addition, a novel structure is produced having a braze like joint with eta phase layers adjacent to the copper based surfaces. The invention utilizes an essentially lead free, high tin solder cascade onto a preferably cool tube, generally with a limited time of contact between the liquid solder and the tube, and with a combination air quench and wipe to remove excess solder and solidify the remaining solder. Thus a braze like joint is achieved having better heat conduction and closer thermal expansion match. This finned heat exchanger tubing is generally useful for liquid to gas type heat exchangers and especially useful for hydrogen coolers for electrical generators.

Abstract: A process for brazing a sleeve within a tube which is resistant to longitudinal expansion is disclosed herein. In the first step of the process, a thermally induced radial expansion is induced in the tube in a first longitudinal section of the tube which does not include the ring of brazing alloy which circumscribes the sleeve. In the second step of the process, a brazing heat is applied across the longitudinal section of the tube which does include this ring of brazing material. The residual tensile stress created by the thermally induced radial expansion in the tube avoids the creation of gaps in the braze joint between the sleeve and the inner walls of the tube. This process is particularly useful in creating high-quality braze joints in sleeving operations in nuclear steam generators, where the heat exchange tubes which need to be sleeved may be partially or completely prevented from expanding in the longitudinal direction due to sludge deposits in the generator.

Abstract: An aluminum or aluminum alloy shape for manufacture of heat exchangers, coated with a metallic layer of a zinc-base alloy constituting a fluxless soldering or low temperature brazing material when heated. A process for direct coating of formed aluminum shapes in nascent state includes the steps of providing a non-reactive atmosphere around the shape, providing a coating material of zinc-base alloy and bringing the aluminum shape and the coating material into contact and maintaining the contact at an elevated temperature for a predetermined period of time for forming a coherent coating on the aluminum shape.

Abstract: A method for replacing tubes in a drum or header without removing the whole tube entirely is disclosed. According to the method, the old tube is cut off level with the header-member; a recess coterminous with the diameter of the tube is machined into the header creating a seat for a new tube; the recessed old tube end is beveled and the old tube is welded into the header-member along the bevel; and a new tube is inserted into the seat and welded to the exterior of the header-member. In a preferred embodiment, a countersink is machined in the surface of the header-member to create a greater surface for welding of the new tube.

Abstract: A method of making the heat exchanger is also disclosed which includes a ring which is slipped over the periphery of the second tube retaining plate and brazed thereto and a gasket which is slipped over the tube core to form a seal between the first end portion and the elongated housing. An O-ring is slipped over the ring after the replacement of the core tubes within the housing. The O-ring seal forms a seal between the ring and the housing when the two end portions are moved towards each other by adjustable tie rods. An alternative embodiment of the invention includes an annular ledge defined by a ring or seal seat encircling the tube retaining plate and an annular shoulder extending between a bore and a counterbore of the elongated housing. The ledge and the shoulder are coplanar such that an O-ring pressed against a washer seated against the ledge and shoulder seals the annular groove between the tube retaining plate and the housing.

Abstract: A method of forming thin, uniform braze joints is effected through the use of curtain coating. Braze powder is admixed with a liquid polymeric binder to form a slurry. The slurry is forced through the slots in a curtain coating head and deposited on at least one of the metal surfaces to be bonded together. The method has particular utility for bonding fin/plate sections of a heat exchanger where the fins have a U-shaped cross section. The slurry is deposited on the top portion of the fin and the side portion of the fin and wiped from the top portion leaving braze material primarily on the side wall portion. When the plates are contacted to the fins and heating performed, a bond is effected with maximum plate-to-fin contact for high heat transfer and a strong braze joint.

Abstract: The process steps for sealing a leak in rolled tube/tubeplate joints in heat exchange units comprise removing a portion of the tube end (2) and of the tube-plate (1) by a milling cut (6) and joining the surfaces thus formed by a weld seam (7) of preferably lens-shaped cross-section.

Abstract: This is a process relating to improvements in the soldering of headers to conventional radiators. Tubular members of the radiator extend through holes in the header. The tubes are initially sealed to the header with a solder having a high temperature melting point T.sub.1. Infrared heat heats the header to a temperature T.sub.2 which is less than T.sub.1 but above a lower temperature T.sub.3 which is the melting temperature of a second solder. Upon the header reaching a selected temperature T.sub.2, a selected amount of the second solder in a molten state is poured in the header to puddle the entire pan area of the header, and allowed to cool to form a very strong soldered connection.

Abstract: A method of manufacturing a heat exchanger in which a laminate prepared by laminating many sheets one upon another so that the neighboring sheets may be formed with bonded portions and non-bonded portions, is expanded in such a direction that the respective sheets are spaced from each other so as to form flow channels or passages between the sheets at the non-bonded portions, and which employs the steps of printing patterns of bonded material onto the sheets, laminating the sheets, and subsequently expanding the laminate of the sheets to form the heat exchanger.

Abstract: In a finned heat exchanger, preferably of aluminum, the feed of the fins (1) are secured to tubular passages (3, 3a, 3b) formed from plates (2) that have been rolled together and then expanded. The bond between the fins (1) and the plates (2) may be an adhesive bond, as by welding or a cohesive bond, as by tight pressing together.

Abstract: Plural vertical tube reactor provides downward flow only, in a serial manner, through a plurality of sets of tubes containing a particulate contact material such as a catalyst which are located in adjacent sectors or reigons of a shell and tube reactor. An empty tube(s) is provided to carry the reactant fluid upwardly from the bottom of one sector of tubes to the top of another. In a two sector configuration, the upper and lower end chambers are each partitioned in half, but the lower partition has a screened port to allow reacted fluid from the first sector to reach, and move upwardly through, an empty tube(s) in the second sector which is isolated from the other tubes in the second sector at its bottom end but not at its top end.

Abstract: The present invention relates to a method and apparatus used to determine the heat flux through a portion of a surface of a heat exchanger tube, using heat flux sensor means that is installed on the inner wall of the heat exchanger tube and send a signal to a connected heat flux meter.

Abstract: Firstly, individual wall parts are welded together from a cooling rib element (1), a tub side wall (2) and a frame part (3), the cooling rib element (1) being reinforced by strips (8, 9) and bars (10, 11). The individual wall parts are mounted on an assembly plate (16) by means of positioning bolts (17) and are held together by stirrups (18). By means of spot welds on the sloping, upwardly bent edges (6, 7) of cooling rib elements (1), the wall parts form a dimensionally stable casing, on which the various vertical and horizontal welds can be made. Due to the fact that the dimensionally stable wall parts are used for producing the transformer tank, the proportion of manual labor in the production of this tank can be considerably reduced, because welding takes place at clearly defined, easily accessible points.

Abstract: A serpentine-type aluminum heat exchanger comprising a serpentine-anfractuous flat tube of an aluminum alloy, a plurality of corrugated fin units made of an aluminum alloy having a high aluminum content of 99 wt. % or more, and brazing metal coating layers fixed onto entire flat surfaces of parallel portions of the serpentine-anfractuous flat tube and for joining the flat tube and the fin units, is produced by preparing the serpentine-anfractuous flat tube of an aluminum alloy, the corrugated fin units and U-shaped members of an aluminum alloy brazing filler metal, closely fitting the U-shaped members onto the parallel portions of the flat tube, disposing the fin units in spaces between adjacent U-shaped members fitted onto the parallel portions of the flat tube, and heating the flat tube, the fin units and U-shaped members in the assembled relation to the brazing temperature.

Abstract: A falling film heat exchanger in which a continuous weld circumferentially joins each tube to the outer surface of the upper, and desirably also the lower, tubesheet. The welds seal the crevices between the tubes and tubesheet holes and prevent corrosion. Since the circumferential welds cannot be deposited if the tube ends extend more than about 2 inches past the tubesheet, extensions can be added by welding.