Abstract: In a thermoelectric power generation module (7) serving as a heat exchanger, a large number of protrusions (5a) at least the surface of which is made of a material with low wettability are formed with a height and width of less than 0.01 mm and arranged with a pitch of less than 0.01 mm on the heat transfer surface (5s) of a heat transfer plate 5, thereby to increase in heat exchange efficiency.

Abstract: Ribbed heat exchange tubes in which the aspect ratio of the ribs is less than 5, provide greater indirect heat exchange than conventional heat exchange tubes with or without fins, when used in a slurry comprising a liquid phase, in which is dispersed flowing gas bubbles or particulate solids and flowing gas bubbles. The ribs, and typically also the longitudinal axis of the heat exchange tubes, are aligned in a direction parallel to, or spirally along the gas bubble flow direction. This is useful to increase either (i) the productivity of a slurry Fischer-Tropsch hydrocarbon synthesis reactor without an increase in the temperature in the reactor or (ii) increasing the production of higher molecular weight hydrocarbons by reducing the reaction temperature at a given feed conversion.

Abstract: A corrosion-resistant, copper-finned heat exchanger for a water heater is provided. The heat exchanger includes a conduit through which water runs, heat-transfer fins extending from the conduit and an anti-corrosive coating containing electroless nickel. The heat-transfer fins contain copper, and the coating is deposited directly onto at least one of the copper heat-transfer fins.

Abstract: A condensing heat exchanger structure in contact with a combustion environment and which structure includes a ferrous substrate is provided with a corrosion resistant diffusion coating applied to the ferrous substrate via a fluidized bed application. Also provided is a method for improving the corrosion resistance of a condensing heat exchanger structure which includes a ferrous substrate and a surface portion at least partially exposed to a combustion product-containing environment. In such method, a corrosion resistant diffusion coating is applied onto the ferrous substrate via a fluidized bed application.

Abstract: A heat exchanger assembly includes a coated core and an electronic coating wear sensor assembly mounted adjacent to the coated core for monitoring depletion of a coating layer of the core. The coating wear sensor assembly is electrically insulated from the coated core to ensure that an electric circuit of the coating wear sensor assembly does not affect deterioration of the core. The sensor assembly has a pair of spaced electrodes electrically insulated from each other by an insulating spacer forming a coating sample area coated with a sample layer of the coating material that provides conductive bridge between the electrodes. The coating sample area is coated with the same coating composition of the same thickness as the heat exchanger core in order to replicate the same rate coating degradation. The coating wear sensor assembly is connected to a sensing circuit that outputs to a coating condition diagnostic unit.

Abstract: A net-shape molded heat transfer component is provided which includes a thermally conductive core and a metallic coating for reflection of electromagnetic interference and radio frequency waves. The heat transfer component is formed by net-shape molding a core body from a thermally conductive composition, such as a polymer composition, and applying a metallic coating. The molded heat transfer part is freely convecting through the part, which makes it more efficient and has an optimal thermal configuration. Additionally, the part is shielded from electromagnetic interference and radio frequency waves, thus preventing the transfer of same into the circuitry housed by the part. In addition, the coating also seals the conductive polymer core against moisture infiltration, making the part well suited for telecommunications applications in potentially harsh environments.

Abstract: A film is adhered to a metal plate of a condensing heat exchanger by a cured layer of silicone RTV elastomer to prevent corrosion of the condensing heat exchanger. A layer of solid silicon RTV elastomer including an organosilicone functional group is applied on the pretreated metal surface. The metal plate is heated and a protective film is then applied. The film is adhered to the surface of the metal sheet by curing the layer of silicone RTV elastomer with the water. The water reacts with the organosilicone functional groups on the silicone RTV elastomer layer, cross-linking the organosilicone functional groups to create an adhesive surface which adheres the film to the surface.

Abstract: A hydrophilic modification method comprising

Abstract: There is disclosed a heat exchanger made of an aluminum alloy having a radiator part (10) and an oil cooler part (11) in combination and manufactured integrally by the brazing method, wherein a refrigerant tank (13) for covering and sealing the oil cooler part is made of an aluminum alloy, an aluminum alloy containing Si in an amount from more than 7.0 wt % to 12.0 wt %, Fe in an amount from more than 0.05 wt % to 0.5 wt %, Cu in an amount from more than 0.4 wt % to 8.0 wt %, Zn in an amount from more than 0.5 wt % to 10.0 wt %, and the balance of aluminum and inevitable impurities is used as a filler material of brazing sheets that are used for the oil cooler part and are brazed in the tank, and the refrigerant tank is assembled integrally with the radiator part and the oil cooler part by brazing with the brazing material.

Abstract: A heat pipe has at least one diamond element through which at least a portion of heat flowing into the heat pipe passes.

Abstract: A condensing heat exchanger is formed of norbornene polymer, preferably a norbornene homopolymer or copolymer. A plurality of norbornene polymer pellets are melted and extruded to form a first tube. The tube is then blow molded into a mold. A second extruded tube is also blow molded into a U-shape, and the first tube is positioned in the U-shaped opening to form a cell. The ends of the cells are attached to a holding plate by thermal adhesion or heating and flaring. Norbornene polymer possesses exceptional thermal resistance to the high temperature flue vent gases and has physical and chemical resistance to the acidic condensate formed by the condensing heat exchanger.

Abstract: A method for the quick classification of structured inner and/or outer surfaces of heat exchanger tubes by means of Doppler radar spectroscopy. The measured variables are determined from the frequency spectra. Surface integral A, average value m and variance S (or standard deviation &sgr;={square root over (S)}) correlate directly with the geometric parameters of the structure morphology. They permit direct conclusions regarding the heat transfer characteristics (evaporation/condensation performance) of the respective structure, in particular no tube samples ready for use are needed for the heat transfer classification.

Abstract: A primary heat exchanger of a condensing furnace or a single heat exchanger of a mid-efficiency furnace is electrochemically coated with a coating of copper metal. The copper coating is oxidized with an aqueous oxidizing alkaline solution to form a matte black layer of cupric oxide. As the layer of cupric oxide is black, the layer has a high emissivity and emits more heat, increasing the efficiency of the primary heat exchanger. Alternatively, iron can be electrochemically coated on the primary heat exchanger and oxidized to black magnetite to increase emissivity.

Abstract: A thermoplastic polymer film is directly extruded onto the heated surface of a metal condensing heat exchanger. Any thermoplastic polymer capable of being adhered to the metal surface of the condensing heat exchanger can be utilized. Preferably, the thermoplastic polymer is a polyester, a polyolefin with an added maleate or tackifier to ensure adhesion, polyetherimide, polyethersulfone, polysufone or polyimide. The thermoplastic film must be resistant to the conditions of the condensing heat exchanger, such as the high temperature flue vent gases and the acidic condensate formed from condensation.

Abstract: A regenerative circuit structure is built up by implementing the following steps in particular: an intermediate layer is made on a support core representing the inner profile of the structure; a series of channels regularly distributed around the core is made with the channels opening to face the intermediate layer, each of the channels being provided with a soluble insert; the support core is preheated and the body of the structure is made by thermal spraying under a vacuum; channels are machined in the body from the outside, and said channels are filled by means of soluble inserts; a closure layer is formed to close the channels in the body, and an outer envelope is formed by thermal spraying under a vacuum, after preheating; and all of the soluble inserts and the intermediate layer are eliminated.

Abstract: An economically formed tube of rectangular or oval-like cross section and with a corrugated internal fin includes spaced, relatively long side wall sections joined at their ends by relatively short end wall sections. An integral fin within the tube has crests and valleys defining a plurality of flow paths within the tube and is formed of a corrugated section of a strip employed to form one of the side walls and at least part of both of the end walls.

Abstract: The invention relates to a process for the production of a heat transfer device, which comprises electroless chemical deposition of a metal/polymer dispersion layer, in which the polymer is halogenated, on a heat transfer surface. The invention furthermore relates to a process for the production of a heat transfer device, wherein a metal/phosphorus layer with a thickness of from 1 to 15 &mgr;m is applied by electroless chemical deposition before application of the metal/polymer dispersion layer. The invention furthermore relates to a heat transfer device which can be produced by a process according to the invention, and to the use of a coating, produced by electroless chemical deposition of a metal/polymer dispersion layer, in which the polymer is halogenated, for reducing the tendency of the coated surfaces to accumulate solids from fluids, causing fouling.

Abstract: A fluid pipe (14) for fluid flow between a pair of manifolds of a heat exchanger and which is formed from a single piece of sheet metallic material having a cladding on at least one surface, the fluid pipe having a first side wall (40) having a first portion (46) and a second portion (48); a second side wall (42) extending substantially parallel to and spaced from the first side wall; a pair of end walls (44) connecting the first and second side walls; first, second and third internal walls (50-54) positioned internally of the first and second side walls and the end walls, the first, second and third internal walls being spaced apart and spaced from the end walls, and extending between the first and second side walls, the first internal wall being of double the thickness of the sheet and being positioned intermediate the second and third internal walls; a first planar side portion (56) connecting the first and second internal walls and contacting a first planar part (58) of the internal surface of the second

Abstract: In a heat transfer pipe, annular grooves in a direction inclined at an angle of 45° to 90° with respect to an axis of the pipe are continuously formed at an interval in a longitudinal direction of the pipe. The annular grooves desirably have a groove depth of 0.20 mm or more, and a groove pitch of two to five times larger than the groove depth. Moreover, a ratio W/P of a bottom width W of projections of the grooves to the groove pitch P is desirably 0.1 to 0.9.

Abstract: The heat exchange tubes of the invention are provided with an inner wall having an increased surface area for contact with a fluid circulating through the tube for the greater exchange of heat energy between the circulating fluid and an external fluid. The outer wall of the heat exchange tube is provided with a series of radially outwardly extending members for increasing the heat exchange surface of the outer wall of the tube.

Abstract: A process for producing a carbon foam heat sink is disclosed which obviates the need for conventional oxidative stabilization. The process employs mesophase or isotropic pitch and a simplified process using a single mold. The foam has a relatively uniform distribution of pore sizes and a highly aligned graphic structure in the struts. The foam material can be made into a composite which is useful in high temperature sandwich panels for both thermal and structural applications. The foam is encased and filled with a phase change material to provide a very efficient heat sink device.

Abstract: A method of making an improved heat transfer tube. The inner surface of the tube has a primary set of fins and an intermediate sets of fins positioned in the areas between the primary fins and at an angle relative to the primary fins. While intermediate fins may be used with primary fins arranged in any pattern, in a preferred embodiment of the inner surface tube design, the intermediate fins are positioned relative to the primary fins to result in a grid-like appearance. Tests show that the performance of tubes having the intermediate fin designs of the present invention is significantly enhanced. A first set of rollers creates the primary and intermediate fin designs on at least one side of a board. A second set of rollers may be used to further enhance the performance.

Abstract: An improved heat transfer tube and a method of formation thereof. The inner surface of the tube has a primary set of fins and an intermediate sets of fins positioned in the areas between the primary fins and at an angle relative to the primary fins. While intermediate fins may be used with primary fins arranged in any pattern, in a preferred embodiment of the inner surface tube design, the intermediate fins are positioned relative to the primary fins to result in a grid-like appearance. Tests show that the performance of tubes having the intermediate fin designs of the present invention is significantly enhanced. A first set of rollers creates the primary and intermediate fin designs on at least one side of a board. A second set of rollers may be used to further enhance the performance.

Abstract: A heat sink is manufactured by forming a fin 2 for dissipating heat by separating a length of material from a substrate 1 while leaving the proximal end attached to the substrate 1. The fins are cut from the substrate by stamping process using the stamping single or progressive die tooling cutting the substrate 1 along dotted line 16. The heat sink is a unitary construction, with the fins 2 being integrally formed with the substrate 1.

Abstract: A tube for a heat exchanger consists of a folded metal strip having an outer face covered with a plating of brazing alloy (31) and including at least one folded border (28) having a sheared edge bearing on an inner face (34) of the metal strip. The metal strip is folded by passing through a series of successive rollers. The sheared edge is covered with a layer of brazing alloy (31) which has advantageously been pushed back by the rollers from the outer surface towards the sheared edge. According to the method, the metal strip is made to pass between a series of rollers, each roller including a surface which exhibits an inclination with respect to the rotational axle of the rollers, the inclinations of the successive rollers continually increasing.

Abstract: To make stress corrosion cracking caused by precipitation of a &bgr; layer (Mg2Al3) in a welding part (5) or in the periphery of the welding part (5) hard to occur. An apparatus body (1) and a header (3) formed of an aluminum alloy with precipitation of magnesium suppressed by standardized heat treatment are assembled and welded, and natural gas containing mercury is subjected to heat exchanging. There are provided with backing metal (4) disposed on the back of the inner wall surface of one header (3) prior to standardized heat treatment and placed in contact with the other apparatus body (1) at the time of assembling and welding, a welding part (5) formed by being assembled and welded using first welding metal containing magnesium at percent content not less than 2.

Abstract: The invention relates to heat-exchanger tubes structured on both inner and outer sides with excellent heat-transfer characteristics, which have recesses on the outside and ribs with specific dimensions on the inside. The structuring tools utilized for the various method modifications are adjusted in such a manner that they are not only able to create aligned, continuous grooves and non-aligned, spaced apart recesses but also secondary structures. The heat-exchanger tubes provided preferably with smooth end sections and smooth intermediate sections are utilized in particular in shell and tube heat-exchangers.

Abstract: A corrugated heat exchanger element may have grooves and ribs on the interior and exterior surfaces of the tube. The corrugations on the tube may be linear corrugations or helical corrugations. The texturing of the interior and exterior surfaces of the tube, and the corrugations in the tube may provide a heat exchanger element that has a large surface area. The surface texturing and corrugations may also provide a heat exchanger element that promotes internal mixing of fluids that flow by and through the element. Increased internal mixing and increased surface area of an element may allow the heat exchanger element to have a high heat transfer coefficient. A heat exchanger element or heat exchanger elements may be assembled into a heat exchanger that has a high overall heat transfer coefficient. Ends of the heat exchanger element may be pointed to facilitate attachment of the element to a support structure.

Abstract: The invention relates to a heat exchanger for cooling a circulating water of a fuel cell. This heat exchanger includes (1) an aluminum member having an inner surface which defines an inner space in the aluminum member such that the circulating water is allowed to flow through the inner space; and (2) a resin coating layer formed on the inner surface of the aluminum member. It becomes possible to prevent contamination of the circulating water by the provision of the resin coating layer. The heat exchanger can be produced by a first process including (a) providing a core portion having tubes made of aluminum and corrugated fins, which are alternately arranged; (b) assembling the core portion and a tank made of aluminum into an assembly; (c) brazing the assembly by heating into a brazed assembly; and (d) coating the inner surface of the brazed assembly with a resin coating layer.

Abstract: A mechanical assembly is comprised of a heat exchanger for an integrated circuit. In the assembly, a retainer for a liquid has a bottom with an opening thru which the heat exchanger extends such that a face of the heat exchanger is surrounded by the retainer. Also in the assembly, a compliant member forms a seal for the liquid between the heat exchanger and the retainer. This mechanical assembly is useful in fabricating an alloy film on the heat exchanger's face.

Abstract: A heat exchanger tube, which has a high pressure resistance, includes a tube body, wherein the interior of the tube body defines a fluid flow passage. The inner and outer surfaces of the tube body of the heat exchanger tube defines heat entrance and exit surfaces for the fluid. The tube body of the heat exchange tube has first and second wall portions which are opposed to each other. Either the first wall porition has a plurality of bowl-shaped bulging wall portions which bulge toward the direction of the second wall portion to fixedly meet the second wall portion or else both the first and second wall portion both have a plurality of bowl-shaped bulging wall portions which are correspondingly located so that a bulging leading end of a bowl-shaped bulging wall portion in a first wall portion bulges toward and fixedly meets a bulging leading end of a bowl-shaped bulging wall portion in the second wall portion which bulges toward the first wall portion.

Abstract: This invention provides heat transfer systems and methods of cooling surfaces and heating liquids which employ surfaces including a minimum density of discrete, nucleation sites having a conical cross-section tapering to a minimum predetermined depth. These surfaces are placed in contact with a refrigerant having a preselected boiling point so that the nucleation sites become largely flooded with the refrigerant. The nucleation sites permit nucleate boiling of a refrigerant without a temperature overshoot on the initial ascent. In more preferred variations of this invention, specific site spacing and geometries are employed to contain tiny bubble embryos, which minimize hysteresis and reversal of trend effects.

Abstract: The invention relates to a component, in particular a heat exchanger, in particular for motor vehicles, having a finned tube block. Preferably, at least one inlet chamber and at least one outlet chamber are provided having walls made of a synthetic resin material possessing a heat- and/or chemical-resistant coating.

Abstract: The heat exchanger according to the invention consists of two flat or slightly incurved parallel surfaces formed in two sheets of metal (2) and (3). The longitudinal edge pieces (8) and (9) and transverse edge pieces (12) and (13) have rounded edges. The entire exterior surface is coated with enamel. These exchangers may be used in groups of several parallel units arranged inside a tubular body, or they may be disposed in a radiating pattern inside a cylindrical tank in a chemical reactor, forming a complex exchanger. This invention is of interest to manufacturers of industrial heat exchangers, particularly exchangers designed for the chemcial, pharmaceutical or agricultural/food industries.

Abstract: A heat exchanger includes an aluminum member coated with a resin. The resin-coated aluminum member may be formed as a constituent part, eg., a heat transfer member, a heater core, or the like, of the heat exchanger. In such heat exchangers, the aluminum member is connected to other resin-coated aluminum members by fusing the resin. Energy consumed during the connection of the aluminum members of the heat exchanger may be effectively reduced, and the manufacturing cost of the heat exchanger may be reduced, compared with that of heat exchangers made according to known methods that use a brazing filler metal.

Abstract: The invention relates to a heat-transfer tube, in particular an evaporator tube, with fins circumferentially extending on the shellside, which fins are shaped to essentially closed-off channels. The channels are open to the outside through pores with at least two variable sizes. In order to improve the evaporation characteristics, the invention provides advantageous regions for the ratio of the pore sizes and the ratio of the number of pores.

Abstract: A corrugated heat exchanger element may have grooves and ribs on the interior and exterior surfaces of the tube. The corrugations on the tube may be linear corrugations or helical corrugations. The texturing of the interior and exterior surfaces of the tube, and the corrugations in the tube may provide a heat exchanger element that has a large surface area. The surface texturing and corrugations may also provide a heat exchanger element that promotes internal mixing of fluids that flow by and through the element. Increased internal mixing and increased surface area of an element may allow the heat exchanger element to have a high heat transfer coefficient. A heat exchanger element or heat exchanger elements may be assembled into a heat exchanger that has a high overall heat transfer coefficient. Ends of the heat exchanger element may be pointed to facilitate attachment of the element to a support structure.

Abstract: The present invention provides a heat exchange element for particular use in a film heat exchanger, such as a distillation system. The heat exchange element includes a substrate having a first surface and an opposing second surface. The first surface acts as a condenser surface. The heat exchange element further includes a composition disposed on at least a portion of the second surface. The composition has an exposed hydrophilic surface so as to provide a hydrophilic evaporator surface due to the composition being hydrophilic in nature. In contrast, the condenser surface is typically hydrophobic in nature. The use of the hydrophilic composition eliminates the nucleation of vapor bubbles and prevents gas film (or gas blanket) formation on the evaporator surface. As a result, the thermal resistance through the heat exchange element is decreased and the efficiency of the heat exchange element is increased.

Abstract: The invention relates to a heat exchanger, which includes a pipe, heat conductive fins having an elongate cross-section, and a coating of silver applied to the outer surface of the fins and the outer surface of the pipe adjacent to the fins. The fins of the heat exchanger, are a metal wire helically wound around the pipe, are connected to the pipe solely by the coating of silver.

Abstract: A thermosyphon radiator comprising a sealed panel containing a reservoir of water in a lowermost part of the panel and a heating member, e.g. a hot water pipe, extending through the lowermost part of the panel, the member being at least partially immersed in the liquid.

Abstract: The present invention provides an improved heat transfer surface. The improved heat transfer comprises: a surface covered with fin convolutions. The fin convolutions have fin tips extending from the surface. The fin tips have a first plurality of notches and a second plurality of notches wherein the first notches and the second notches are of different sizes.

Abstract: A heat exchanger has a tank for accommodating a heat medium therein and a tube connected to the tank through a core plate. Specifically, an end portion of the tube is inserted into a connection hole of the core plate and is mechanically joined thereto. A joined portion of the tube and the core plate is covered with adhesive through a wettability improving film for improving wettability of the adhesive to the joined portion. As a result, a sealing property between the tube and the core plate is easily and stably improved by the adhesive.

Abstract: Oligomeric silane coating compositions containing, for example, methyltrimethoxysilane, are used to coat new or used heat exchange apparatus, such as HVAC systems, to greatly improve the heat transfer efficiency and prevent or inhibit corrosion. These oligomeric coating compositions are able to fill microvoids in the heat exchange surfaces, and penetrate into the microcavities at the interface of swaged or force fit surfaces, such as fins and tubes. The oligomeric silane coating compositions are highly active and will form bonds not only with the metal and metal oxides of the heat transfer surfaces, but will also displace gasses or liquids at the heat transfer contact surfaces and form chemical and/or hydrogen bonds with the oxides and chemical impurities. By so doing, a parallel heat transfer pathway is formed. The applied coatings may be as thin as only a few millionths of an inch and will fill microcavities to a depth of up to about 2000 nanometers.

Abstract: A heat transfer tube utilized in a condenser or an evaporator of a heat exchanger includes a plurality cavities to increase heat transfer. A plurality of substantially trapezoidal shaped substantially parallel ribs are formed by a first roll embossing step. A second roll embossing step is repeated at a different helix angle to slightly deform the ribs, creating a plurality of substantially parallel microgrooves and a cavity on the interior end of each microgroove. The cavities are substantially branched or substantially V-shaped and increase heat transfer.

Abstract: A metallic heat transfer tube, in particular for the evaporation of liquids from pure substances or mixtures on the outside of the tube. Fins are integrally formed on the outside of the tube. Recesses are arranged in the area of the base of the primary grooves and extend between the fins. The recesses are in the form of re-entrant secondary grooves. The mechanical stability of the tube is not negatively influenced because material is primarily removed from the fin flanks toward the base of the groove so that the re-entrant secondary grooves are radially open.

Abstract: The present invention discloses an apparatus including a magnesium alloy vessel substantially free of aluminum and zinc, with the vessel having a hollow interior cavity containing a working fluid, wherein the improvement includes the formation of a stable, protective layer on the inside wall of the vessel, the layer establishing compatibility with the working fluid and preventing base metal corrosion by the working fluid, the vessel including magnesium in combination with a gettering metal.

Abstract: To provide a high heat transfer performance with a heat transfer pipe used to a condenser and an evaporator in a refrigerating cycle using a refrigerant mixture, the heat transfer pipe includes main grooves and auxiliary grooves each formed on the inner surface of the heat transfer pipe with the main grooves intersecting the auxiliary grooves, wherein the main grooves are separate by ridges, and the ridges are divided into ribs by the auxiliary grooves, and wherein a length of the ribs formed along the direction of the main grooves is made longer than the length of the ridges, a width of the auxiliary grooves is made smaller than the length of the ribs and further the auxiliary grooves are formed in a direction where a pressure gradient in the heat transfer pipe is reduced.

Abstract: An aluminum alloy containing (in wt. %): 0.2-0.5 Fe; 0.7-1.2 Si; 1.2-1.6 Mn; up to 0.3 Mg; up to 0.5 Cu; up to 0.2 Zn; up to 0.1 Ti is used to make the fins of heat exchangers particularly car radiators. The finstock has high post braze strength and thermal conductivity, and has a sufficiently electronegative potential as to be capable of acting as a sacrificial anode for the heat exchanger tubes. By virtue of the absence of Sn, In, and Cr, these heat exchangers can be scrapped and melted for re-use.

Abstract: A method for making a film having improved wettability properties for use with a heat exchanger of a condensing furnace or an air conditioner. The film can be made of any thermoplastic film which bonds to metal. Polar particulates are mechanically are adhered to and embedded in the upper surface of the heated film. The particulate can be surface treated to either enhance adhesion of the particulate to the film or to enhance wettability. In another embodiment, the film is coated with an adhesive substance or a mixture of reactants, the particulate pressed into and adhered to the coating.

Abstract: A finned heat exchange tube includes a metal cylindrical central tube having an outer surface and a metal fin helically disposed on and in thermally conductive contact with the outer surface of the tube. The cross-section of the fin is trapezoidal in shape, with a longer and a shorter base, the longer base being in contact with the outer surface of the tube. Alternatively, the fin can have a cross-section substantially rectangular in shape, having rounded comers and sides of longer and shorter dimensions perpendicular to one another, a side of the shorter dimension being in contact with the outer surface of the tube. A process for forming a heat exchanger tube comprises helically winding and securing a metal fin on an outer surface of a metal cylindrical central tube. The fin, which is in thermally conductive contact with the central tube, has a cross-section that can be trapezoidal or substantially rectangular in shape.