Hybrid heat exchanger

Abstract

A hybrid heat exchanger including metal serpentine tubes is provided. [Solution] A hybrid heat exchanger comprising a metal serpentine tube having an inlet end portion for receiving process fluid, an outlet end portion, and a series of extensions and return bends for directing the process fluid from the inlet end portion to the outlet end portion of the metal serpentine tube. The hybrid heat exchanger further comprises a thermally conductive polymer body thermally integrated with the serpentine tube. The thermally conductive polymer body has an outer surface in contact with a fluid, such as air and / or water. The thermally conductive polymer body is configured to transfer heat between the metal serpentine tube and the fluid in contact with the outer surface of the thermally conductive polymer body. The outer surface of the thermally conductive polymer body includes surface-reinforced features that affect the flow of fluid across the outer surface of the thermally conductive polymer body.

Description

Technical Field

[0001] Cross - reference to Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 129,796, filed on December 23, 2020.

[0002] Field

[0002] This disclosure relates to heat exchangers, more specifically, indirect heat exchangers.

Background Art

[0003] Background

[0003] Various types of indirect heat exchangers are known. Plate - frame heat exchangers, pillow - plate heat exchangers, and plate - coil heat exchangers all use formed metal plates that are either welded together and then hydraulically expanded or gasketed together to form a liquid - tight cassette. These indirect heat exchangers are collectively referred to as plate heat exchangers. Similarly, serpentine coil indirect heat exchangers are also often used.

[0004]

[0004] Direct heat exchangers, such as heat - formed polyvinyl chloride (PVC) fillers, that can be used in combination with indirect heat exchangers are also known. For example, the filler can be positioned above or below the serpentine coil to provide a region for the evaporating fluid to interact with air either before or after the evaporating fluid contacts the serpentine coil.

[0005]

[0005] Plate heat exchangers can be relatively expensive and difficult to manufacture, and in some cases the cost per ton of cooling is higher than what the market would impose. Serpentine coil heat exchangers, on the other hand, can be less expensive, but they cannot match the surface area density, and therefore the heat exchange efficiency, of plate heat exchangers. Stainless steel (SST) plate heat exchangers typically cost up to three or four times more, and at the same time have lower conductivity than their hot-dip galvanized black steel (HDG) equivalents, but SST plate heat exchangers are often specified for the purpose of enabling higher corrosion resistance. [Overview of the project] [Problems that the invention aims to solve]

[0006]

[0006] Thermally conductive polymers are used in low-pressure heat exchangers and may be preferable to metal materials from a material cost standpoint. However, the strength of these heat exchangers is not sufficient to withstand the internal pressures required for certification in many fields, such as refrigerant coils. For example, in some applications of plate heat exchangers, the plate heat exchanger is required to withstand 150 psig or more, e.g., 300 psig or even 1000 psig. It is therefore impractical to manufacture plate heat exchangers from thermally conductive polymers for these high-pressure applications using known thermally conductive polymers. [Brief explanation of the drawing]

[0007] Brief explanation of the drawing [Figure 1]

[0007] A perspective view of a hybrid heat exchanger having a metal serpentine tube and a body of a thermally conductive polymer that is thermally integrated with it. [Figure 2]

[0008] Figure 1 is a perspective view of a hybrid heat exchanger assembly including multiple hybrid heat exchangers connected to inlet and outlet headers. [Figure 3]

[0009] Figure 2 shows a cooling tower including a hybrid heat exchanger assembly. [Figure 4]

[0010] This is a cross-sectional view along line 4-4 in Figure 1, showing the sheath portion of the main body that receives the extended portion of the serpentine tube. [Figure 5]

[0011] This is a cross-sectional view of another hybrid heat exchanger having a thermally conductive polymer body containing two sheets that are joined together using a thermally conductive paste around two fluid conduits. [Figure 6]

[0012] This is a cross-sectional view of a hybrid heat exchanger having a thermally conductive polymer body, including sheet and cover portions connected around a fluid conduit. [Figure 7A]

[0013] This is a schematic diagram of a method for forming a hybrid heat exchanger using additive manufacturing. [Figure 7B]

[0013] This is a schematic diagram of a method for forming a hybrid heat exchanger using additive manufacturing. [Figure 7C]

[0013] This is a schematic diagram of a method for forming a hybrid heat exchanger using additive manufacturing. [Figure 7D]

[0014] These are schematic diagrams of thermally conductive polymer filaments that can be used in the methods shown in Figures 7A-7C. [Figure 7E]

[0014] This is a schematic diagram of a thermally conductive polymer filament that can be used in the methods shown in Figures 7A to 7C. [Figure 7F]

[0014] This is a schematic diagram of a thermally conductive polymer filament that can be used in the methods shown in Figures 7A to 7C. [Figure 8A]

[0015] This is a schematic diagram of a method for forming a hybrid heat exchanger using injection molding. [Figure 8B]

[0015] This is a schematic diagram of a method for forming a hybrid heat exchanger using injection molding. [Figure 8C]

[0015] This is a schematic diagram of a method for forming a hybrid heat exchanger using injection molding. [Figure 9]

[0016] A perspective view of a hybrid heat exchanger assembly having a frame for maintaining the hybrid heat exchangers in fixed positions relative to each other. [Figure 10]

[0017] A perspective view of a single thermally conductive polymer body that can be integrated with a plurality of fluid conduits. [Figure 11]

[0018] A schematic view of a hybrid heat exchanger having a straight extension and a return bend of a tube of the hybrid heat exchanger that is thermally integrated with the thermally conductive polymer body of the hybrid heat exchanger. [Figure 12]

[0019] A partial view of a hybrid heat exchanger having a fluid conduit and a thermally conductive polymer body, and FIG. 12 shows the chevrons on the outer surface of the body. [Figure 13]

[0020] A cross-sectional view taken along line 13-13 in FIG. 12 showing the ridges and grooves of the chevrons on the body. [Figure 14]

[0021] A perspective view of a hybrid heat exchanger having a fluid conduit extending through the body of the thermally conductive polymer. [Figure 15]

[0022] A partial perspective view of the hybrid heat exchanger of FIG. 14 showing the straight extension and the return bend of the tube of the hybrid heat exchanger. [Figure 16]

[0023] A perspective view of a hybrid heat exchanger having a tube extending into the body of the thermally conductive polymer, and FIG. 16 shows the fins of the thermally conductive polymer body.

Mode for Carrying Out the Invention

[0008] Detailed Description

[0024] According to one aspect of the present disclosure, a hybrid heat exchanger is provided, comprising a metal serpentine tube having an inlet end portion for receiving process fluid, an outlet end portion, and a series of extensions and return bends for directing the process fluid from the inlet end portion to the outlet end portion of the metal serpentine tube. The hybrid heat exchanger further comprises a thermally conductive polymer body thermally integrated with the serpentine tube. The thermally conductive polymer body includes an outer surface in contact with a fluid, such as air and / or an evaporative liquid, such as water. The thermally conductive polymer body is configured to transfer heat between the metal serpentine tube and the fluid in contact with the outer surface of the thermally conductive polymer body. The outer surface of the thermally conductive polymer body includes surface-reinforced features that affect the fluid flow across the outer surface of the thermally conductive polymer body.

[0009]

[0025] A hybrid heat exchanger having a metal tube and a thermally integrated thermally conductive polymer body combines the strength of the metal tube, which can withstand high process fluid operating pressures, with the easily manufactured thermally conductive polymer body. High process fluid operating pressures can be at least 150 psig for process fluids such as water, glycol, and brine, up to 410 psig for refrigerants such as ammonia or HCFC-22, or 1200 psi or more for refrigerants such as CO2. Furthermore, surface reinforcement features on the outer surface of the thermally conductive polymer body improve the thermally conductive polymer body's ability to facilitate heat transfer between the process fluid in the metal serpentine tube and the fluid on the outer surface of the thermally conductive polymer body.

[0010]

[0026] According to another aspect of the present disclosure, a heat exchanger system is provided which includes an inlet header, an outlet header, and a plurality of fluid conduits made of a first thermally conductive material for receiving process fluid. The first thermally conductive material may be a metal, such as stainless steel or copper, a non-metallic material, such as ceramic, a composite material, or a conductive polymer. Each fluid conduit has an inlet end portion connected to the inlet header, an outlet end portion connected to the outlet header, and an intermediate portion along the fluid conduit between the inlet and outlet end portions. The fluid conduits are configured to allow process fluid to flow from the inlet header to the outlet header.

[0011]

[0027] The heat exchanger system includes a body of a thermally conductive polymer having an outer surface that is different from the first thermally conductive material. The thermally conductive polymer body is in thermal contact with the intermediate portion of the fluid conduit and is configured to facilitate heat transfer between the process fluid and the fluid on the outer surface of the thermally conductive polymer body as the process fluid moves through the intermediate portion of the fluid conduit. Since the thermally conductive polymer body is made of a different material from the first thermally conductive material of the fluid conduit, the material of the thermally conductive polymer body can be selected without being limited by pressure handling requirements, while the first thermally conductive material can be selected to provide sufficient strength to resist high-pressure process fluids.

[0012]

[0028] This disclosure also provides a method for forming a hybrid heat exchanger, comprising providing a metal tube to receive a process fluid and manufacturing a body of a thermally conductive polymer. The body has an outer surface with surface-reinforced features to influence the fluid flow on the outer surface of the body. The method further comprises thermally integrating the thermally conductive polymer body and the metal tube. In one embodiment, manufacturing comprises using additive manufacturing to make the body, and integrating the thermally conductive polymer body and the metal tube comprises using additive manufacturing to form the body around the metal tube. In another approach, manufacturing comprises using additive manufacturing to form the body, and integrating the thermally conductive polymer body and the metal tube comprises assembling the body parts around the metal tube.

[0013]

[0029] In one aspect of this disclosure, a method is provided for producing a lower-cost yet highly efficient hybrid plate heat exchanger, comprising additive manufacturing, e.g., three-dimensional (3D) printing, molding, and / or attaching a thermally conductive polymer to one or more fluid conduits, e.g., one or more metal tubes. In some examples, air and water operating features are formed via molding or 3D printing techniques to become polymer sheets of the hybrid plate heat exchanger, which may be used to avoid detours, to optimize the water distribution on the heat exchanger, to facilitate water / air mixing, and / or to provide a thermally conductive polymer or polymer / metal hybrid surface area to enable heat transfer from the tubes. Thermally conductive polymers typically have conductivity comparable to SST metals and up to 10 times higher than conventional polymers, while being less expensive per unit weight. Thus, thermally conductive polymers enable lower-cost construction materials while maintaining thermal performance.

[0014]

[0030] Generally, thermally conductive polymers refer to polymers with thermal conductivity exceeding 2 W / mK, for example, 2 to 100 W / mK, or exceeding 5 W / mK, for example, 10 W / mK. The table below compares the approximate thermal conductivity of various materials measured at 20°C.

[0015] [Table 1]

[0016]

[0031] In one embodiment, metal tubing may be used for process fluid operation to meet the pressure requirements for a hybrid heat exchanger. Examples of metals that may be used for the tubing include aluminum, copper, stainless steel, and carbon steel. Alternative materials for the composition, such as ceramics and conductive polymers, may also be considered for the tubing.

[0017]

[0032] Some described examples involve combinations of dissimilar materials and manufacturing processes (e.g., thermally conductive polymers and metal tubing) to create hybrid heat exchangers. At least one of the hybrid heat exchangers presented herein uses a metal tubing structure to accommodate the internal pressure of a high-pressure process fluid, which may be supplied at over 150 psig, e.g., over 200 psig or over 300 psig, while thermally conductive polymers are used to increase the surface area of ​​the hybrid heat exchanger at a lower material cost than a typical single-material metal plate heat exchanger.

[0018]

[0033] In one aspect of this disclosure, a low-cost plate heat exchanger is provided that can be easily manufactured and configured for various applications (different sizes, dimensions, and patterns for use in specific unit types) without extensive modification of tools or equipment. The plate heat exchanger addresses the pressure handling problem of welded metal plates, where welding is a weak point. The plate heat exchanger is adapted to maintain the surface area density of the heat exchanger while improving cost, manufacturability, and adaptability. The use of a highly conductive polymer material bonded to a tube containing a pressurized process fluid enables superior heat transfer with higher corrosion and fouling resistance, as well as reduced weight, at a lower cost than SST heat exchangers.

[0019]

[0034] Using a first material for process fluid-operating fluid conduits and a second material connected to the fluid conduits allows for heat exchangers that can meet pressure handling requirements while offering engineering flexibility (i.e., designs adaptable to specific applications but not constrained by conventional manufacturing considerations) and cost-effectiveness. A variety of different tube circuits and polymer sheet configurations (e.g., surface patterns) can be used in conjunction with this approach. Additionally, it is conceivable that both features can be combined to create a single-plate heat exchanger by printing or forming fillers as continuities of plates. This technology can be applied in any field where heat transfer into and out of pressurized fluid channels is required (e.g., automotive / aerospace, battery cooling, engine cooling, power engineering cooling, consumer HVAC, high-performance computing cooling).

[0020]

[0035] The examples shown in the diagrams are illustrative and may be modified or redesigned, for example, to optimize the design for mass production and balance cost-to-thermal performance.

[0021]

[0036] With respect to Figure 1, a hybrid heat exchanger 10 is provided through which a process fluid such as water, glycol, brine, ammonia, or CO2 passes so as to be cooled by the hybrid heat exchanger 10. The hybrid heat exchanger 10 includes a fluid conduit, e.g., a tube 11, and a body 12 made of a thermally conductive polymer material. The tube 11 is configured to withstand a high internal operating pressure, e.g., at least 150 psig, imposed inside the tube 11 by the process fluid inside. The body 12 facilitates heat transfer between the high-pressure process fluid moving through the tube 11 and a fluid, e.g., air and / or water, that is in contact with the outer surface 15 of the body 12.

[0022]

[0037] The tube 11 has an inlet end portion 11A, an outlet end portion 11B, and an intermediate portion 9 located along the tube 11 between the inlet and outlet end portions 11A and 11B. In one embodiment, the tube 11 is a serpentine tube, and the intermediate portion 9 includes an extension portion, for example, a straight extension portion 11C, and a return bend 11D. The straight extension portion 11C is arranged as a vertical arrangement of tube portions. The tube 11 may have a single configuration or may be formed, for example, by extruding a tube having a desired cross-section with respect to length. Another approach to forming the tube 11 includes winding a strip of material to a desired cross-sectional configuration and welding the longitudinal edges of the strip together. In another embodiment, the tube 11 may be an assembly of components. For example, the straight extension portion 11C may be made of a first material, and the return bend 11D may be made of a second material, for example, different first and second metals, and the straight extension portion 11C and the return bend 11D are connected together, for example, by welding.

[0023]

[0038] The tube 11 has a total length and a cross-section perpendicular to its length. The cross-section of the tube 11 may be uniform over its length or may vary over its length. For example, the straight extension 11C may have a different cross-section from the return bend 11D. The cross-section of the tube 11 may include, for example, at least one of circular, elliptical, oblong, and transversely elongated cross-sections.

[0024]

[0039] The body 12 has a sleeve portion, such as a sheath 13, that receives the linearly extended portion 11C of the tube 11. The body 12 also has an outer surface 15 which includes surface features 14, such as a three-dimensional surface pattern, that guides the fluid flowing over the outer surface 15 and / or improves heat transfer between the fluid flowing over the outer surface 15 and the body 12. Examples of surface features 14 include protrusions, such as chevrons, peaks and valleys, and raised areas, in order to control the fluid distribution throughout the assembly and to enhance heat transfer between the process fluid in the tube 11 and the fluid in contact with the outer surface 15 of the body 12, such as water and / or air. The surface features 15 can be formed in a variety of different patterns or configurations.

[0025]

[0040] The main body 12 may be made of one or more thermally conductive polymer materials that can provide greater strength and improved thermal performance compared to conventional heat exchanger materials. In one embodiment, the thermally conductive polymer includes an elastomer, such as plastic, synthetic rubber, or natural rubber. The elastomer is impregnated with graphite or metal particles to provide thermal conductivity. In another embodiment, the thermally conductive material includes a polymer and continuous fibers or wires of metal in the polymer.

[0026]

[0041] The thermally conductive polymer of the main body 12 may be a polymer material doped with a metallic material. For example, the thermally conductive polymer of the main body 12 may be thermoplastic polyurethane (TPU) doped with a thermally conductive material. As another example, the elastomer of the thermally conductive polymer of the main body 12 may include polylactic acid (PLA), acrylonitrile butadiene styrene (ABS), or nylon-based materials. The thermally conductive doping material may include, for example, graphite fibers, aluminum fibers, or copper fibers.

[0027]

[0042] In one embodiment, the body 12 is a shell for the tube 11, with the inlet end portion 11A, the outlet end portion 11B, and the returns bend 11D located outside the shell. The body 12 has an outer circumference 8 including vertical edges 8A, 8B and horizontal edges 8C, 8D. Note that the terms vertical and horizontal are used to describe relative positioning rather than, for example, orientation with respect to the Earth.

[0028]

[0043] With respect to Figure 1, the body 12 may have an upper filling portion 5A extending above the uppermost of the straight extensions 11C of the tube 11 and a lower filling portion 5B extending below the lowermost of the straight extensions 11C. The upper and lower filling portions 5A, 5B move along the body 12 and provide additional surface area for a fluid, such as an evaporative liquid, to transfer heat with the body 12. Furthermore, in embodiments in which an evaporative liquid, such as water, is distributed onto the hybrid heat exchanger 10 and airflow is directed along the evaporative heat exchanger 10 in the opposite direction to or across the evaporative liquid, the upper and lower filling portions 5A, 5B provide additional areas for potential and detectable heat transfer between the air and the evaporative liquid. The upper and lower filling portions 5A, 5B may include surface reinforcement features, such as protrusion patterns, chevrons, ridges, grooves, male / female members, etc.

[0029]

[0044] With respect to Figure 2, a hybrid heat exchanger assembly 16 is provided having a plurality of hybrid heat exchangers 10 connected in parallel to an inlet header 17 and an outlet header 18. The tubes 11 of each hybrid heat exchanger 10 define separate flow paths or circuits for process fluid from the inlet header 17 to the outlet header 18. The inlet and outlet headers 17, 18 may be reversed for a given embodiment.

[0030]

[0045] The bodies 12 have gaps 19 between them, allowing fluid to move along the outer surface 15 of the bodies 12. In one embodiment, each tube 11 has its own body 12 integrated with it, with gaps between the bodies 12. In another embodiment, a single body 12 may be integrated (e.g., molded, 3D printed, assembled) with two, three, or more tubes 11. The single body 12 may have through openings therein, allowing air and evaporative fluid to pass through the hybrid heat exchanger assembly 16. Exemplary single body configurations are discussed in more detail below with respect to Figure 10.

[0031]

[0046] With respect to Figure 2, the number of hybrid heat exchangers 10, as well as the configuration of the tubes 11 and body 12, can be customized for a particular application. The body 12 of each hybrid heat exchanger 10 is integrated, for example, laminated on the tubes 11 using additive manufacturing, molded on the tubes 11, and / or mechanically fixed to the tubes 11, to form a continuous plate-type heat exchanger that helps distribute heat from the process fluid in the tubes 11 and enhances the interaction with the fluid in contact with the outer surface 15 of the body 12, such as air and / or evaporative cooling water. For this purpose, surface features 14 are formed on the body 12 in an application-specific manner. Additionally, the body 12 may extend above, below, or both above and below the tubes 11 to create filled portions for the fluid in contact with the outer surface 15 (see 5A, 5B in Figure 1) and to enhance the heat transfer characteristics of the hybrid heat exchanger assembly 16.

[0032]

[0047] With respect to Figure 3, a thermal blockage device, such as a cooling tower 24, is provided, which includes one or more direct and / or indirect heat exchangers, such as a hybrid heat exchanger assembly 16, and packing 34. The cooling tower 24 has an outer structure 26 and one or more fans 28, including fan blades 30 and motors 32. The cooling tower 24 may be, in some examples, an evaporative condenser, a closed-circuit cooling tower, or a dry cooler heat exchanger. The packing 34 is shown below the hybrid heat exchanger assembly 16, but in other embodiments, the packing 34 is above and / or to the side of the hybrid heat exchanger assembly 16.

[0033]

[0048] With respect to Figure 3, the cooling tower 24 has an evaporative liquid distribution system 43 which includes a spray assembly 44 having spray nozzles or orifices 46 for distributing an evaporative fluid, such as water, onto the hybrid heat exchanger assembly 16. The evaporative liquid distribution system 43 includes a wastewater tank 50 for collecting evaporative fluid from the packing material 34 and the hybrid heat exchanger assembly 16, and a pump 52 for pressurizing the collected evaporative fluid through a pipe 54 to the spray assembly 44.

[0034]

[0049] The cooling tower 24 further includes one or more air inlets 35, inlet louvers 58 to prevent evaporated liquid from leaving the cooling tower 24, an air outlet 59, and an eliminator 56 for collecting water mist from the air before it leaves the air outlet 59. A fan 28 is operable to generate or guide an upward airflow over the hybrid heat exchanger assembly 16 and packing 34. In other embodiments, the cooling tower 24 may have one or more fans configured to guide the airflow into a downward or alternating current over the indirect and / or direct heat exchangers of the cooling tower 24.

[0035]

[0050] With respect to Figure 4, a partial cross-sectional view of the hybrid heat exchanger 10 is provided. The straight extension 11C of the tube 11 is received by the sheath portion 13 of the body 12. The sheath portion 13 extends around the entire cross-section of the straight extension 11C for at least a portion of the length 79 (see Figure 1) of the extension 11C. In one embodiment, the hybrid heat exchanger 10 has a thermally conductive paste 80 between the body 12 and the extension 11C to improve thermal contact between the body 12 and the extension 11C. In other embodiments, the thermally conductive paste 80 is not used. For example, the body 12 may be directly printed / molded onto the extension 11C, the extension 11C may be extended to engage with the body 12C (for example, by advancing a ball bearing through the tube 11 to increase the outer diameter of the tube 11, or by applying a pressurized liquid into the tube 11), a mechanical connection for fixing the body 12 and the tube 11, such as a snap-fit ​​or fastening mechanism, or a baked coating method to achieve surface contact between the body 12 and the tube 11 may be used. Optionally, the thermally conductive paste 80 may be a binder or adhesive to provide mechanical stability, such as a non-slip configuration of the tube 11 and the body 12. In one embodiment, the thermally conductive paste 80 may be a coating to protect the tube 11.

[0036]

[0051] With respect to Figure 5, a hybrid heat exchanger 100 similar to the hybrid heat exchanger 10 discussed above with respect to Figure 4 is provided. The hybrid heat exchanger 100 has a body 102 of a thermally conductive polymer. The body 102 includes two sheets 104, 106 assembled around an extended portion 108 of a tube 110. The sheets 104, 106 may include fitting portions, such as snap-fit ​​members, that engage to connect the sheets 104, 106 to the tube 110. The body 102 has a sheath 112 formed by sheath portions 112A, 112B of the sheets 104, 106. The hybrid heat exchanger 100 further includes a thermally conductive paste 114, such as epoxy. The thermally conductive paste 114 may be used to promote heat transfer and / or ensure mechanical stability. In one embodiment, the body 102 is heated to bond the sheets 104, 106 to each other and to the tube 110.

[0037]

[0052] With respect to Figure 6, a hybrid heat exchanger 150 similar to the hybrid heat exchanger 10 discussed above with respect to Figure 4 is provided. The hybrid heat exchanger 150 includes tubes 152 and a body 154 of a thermally conductive polymer. The body 154 has sheets 154A and covers 154B, 154C. Sheet 154A has a different size and shape from covers 154B, 154C. Sheet 154A and covers 154B, 154C cooperate to form a sheath portion 156 of the body 154. The sheath portion 156 has an opening 158 for receiving the tubes 152. Sheet 154A and covers 154B, 154C each have collar portions 160, 162 configured to adorn the outer surface of the tubes 152. In one embodiment, the collar portion 160 of sheet 154A extends around most of the cross-section of tube 152, and the collar portions 162 of covers 154B, 154C extend around the smaller portion of the cross-section of tube 152. In other embodiments, the collar portion 160 may extend around the smaller portion of the cross-section, the collar portion 162 may extend around most of the cross-section, or the collar portions 160, 162 may have similar extents around the cross-section. In one embodiment, the hybrid heat exchanger 150 includes paste 164 in the opening 158 between the body 154 and the tube 11. The paste 164 may be used to promote heat transfer and / or ensure mechanical stability.

[0038]

[0053] With respect to Figures 7A to 7C, an exemplary method for forming a hybrid heat exchanger is provided. The method includes forming a body 200 of a thermally conductive polymer using an additive manufacturing apparatus 202, and integrating the body 200 with tubes 204. The tubes 204 may be, for example, continuously formed metal tubes or tubes made of another thermally conductive pressure-treated material.

[0039]

[0054] The apparatus 202 includes a thermally conductive polymer filament 206 and a gear 208 for passing the filament 206 through a heating chamber 210 used to melt the filament to a nozzle 212. The nozzle 212 stacks the molten filament 214. After stacking, the molten filament 214 becomes a solidified filament 216. In some embodiments, a removable support material, such as a mold plate 218, is provided. The mold plate 218 can be removed, for example, by being crushed or dissolved in a liquid. By removing the mold plate 218, the corresponding shape remains in the solidified filament 216, for example, the projection 221 in Figure 7A is removed, leaving a recess 220 in the solidified filament 216. In some embodiments, a build plate 222 is provided on which the molten filament 214 is initially stacked. The solidified filament 216 can be removed from the mold plate 218 when the body 200 is completed.

[0040]

[0055] In one embodiment, the method shown in Figures 7A-7C involves forming the body 200 using a fused deposition modeling (FDM) 3D printing process. Other additive manufacturing processes such as selective laser sintering, stereolithography (SLA) 3D printing, and / or binder jetting may also be used.

[0041]

[0056] The filament 206 is plasticized in the nozzle 212 and selectively layered one layer at a time to form the desired shape of the body 200. Multiple nozzles 212 may be used to accelerate the process and / or to print different materials (e.g., a conductive polymer in addition to a soluble sacrificial support material). The printed body 200 in Figure 7A includes a colored portion, such as a channel 224, sized to accommodate the tube 204.

[0042]

[0057] The method includes positioning the tube 204 in the channel 224, as shown in Figure 7B. The method also includes continuing to laminate molten filaments 214 to embed the tube 204 in the channel 224, as shown in Figure 7C. The methods in Figures 7A–7C may be aided by thermally conductive paste, baking paint techniques, and / or mechanical fastening methods around the tube 204 to fix all components into a completed, thermally effective assembly.

[0043]

[0058] With respect to Figures 7D to 7F, cross-sections of various types of thermally conductive polymer filaments that can be used by the methods described herein are provided. With respect to Figure 7D, a thermally conductive polymer filament 230 is provided having a matrix phase 231 of a polymer material that may or may not be thermally conductive. The thermally conductive polymer filament 230 further comprises a particle phase 232 of a conductive material such as graphite or metal.

[0044]

[0059] With respect to Figure 7E, a thermally conductive polymer filament 234 is provided, having a thermally conductive matrix 235 and a continuous wire 236. The thermally conductive matrix 235 may be, for example, an elastomer, or a plastic material doped with a thermally conductive material such as graphite, aluminum, and / or copper.

[0045]

[0060] The continuous wire 236 may be made of a metallic material that acts as a thermally conductive material, such as copper and / or nichrome. In embodiments in which the continuous wire 236 includes nichrome, an electric current may be applied to the nichrome material to generate heat in the continuous wire 236. Referring to Figure 3, in one embodiment, the cooling tower 24 may include a power supply 99 that can be operated to apply an electric current to the nichrome wire of the body 12 for an active heating cycle. The active heating cycle may be used as a thawing, freeze prevention method, or to force a phase change in the phase change material of the body 12, as will be discussed below.

[0046]

[0061] With respect to Figure 7F, a thermally conductive polymer filament 240 is provided having a thermally conductive shell 241 made of, for example, TPU, ABS, or PLA plastic. The thermally conductive polymer filament 240 also has a phase change core 242 made of, for example, paraffin, non-paraffinic organic matter, and / or hydrated salt. The phase change core 242 has the ability to undergo, for example, a solid-liquid phase change after the thermally conductive polymer filament 240 has been laminated and cured. The phase change of the phase change core 242 allows thermally conductive polymer body printing using the thermally conductive polymer filament 240 to absorb heat through the changing state of the phase change core 242. In this way, thermally conductive polymer body printing using the thermally conductive polymer filament 240 provides not only energy transfer but also energy storage.

[0047]

[0062] With respect to Figures 8A to 8C, exemplary methods for forming a hybrid heat exchanger 250 (see Figure 8C) using injection molding and a mold 252 are provided. The hybrid heat exchanger 250 includes fluid conduits, such as tubes 260, and a body 262 made of a thermally conductive polymer.

[0048]

[0063] With respect to Figure 8A, the mold 252 has a first mold portion, e.g., an upper pattern 254, a second mold portion, e.g., a lower pattern 256, and a cavity 258 between them. The method includes positioning a fluid conduit, e.g., a tube 260, in the mold 252 and closing the mold 252 so that the tube 260 is in the cavity 258. The tube 260 is positioned in the cavity 258 such that there is sufficient space between the tube 260 and the upper and lower patterns 254, 256 to form the desired thickness of the body 262. Injection molding of a thermally conductive polymer onto the tube 260 allows the polymer to fuse with the tube 260, which fills the opening between the tube 260 and the thermally conductive polymer, improving the thermal contact between the tube 260 and the body 262. Injection molding of a thermally conductive polymer onto the tube 260 also provides structural rigidity for the hybrid heat exchanger 250.

[0049]

[0064] With respect to Figure 8B, the method includes injecting the thermally conductive polymer 270 into the cavity 258 of the mold 252 and filling a portion 272 of the cavity 258. As shown in Figure 8C, the molten front portion 274 of the polymer 270 advances throughout the cavity 258 until the cavity 258 is filled with the polymer 270.

[0050]

[0065] Figure 8C shows the hybrid heat exchanger 250 after the thermally conductive polymer 270 has been injected and before removal or discharge from the mold 252 of the hybrid heat exchanger 250. In some approaches, post-molding or bake-on coating techniques may be applied after the polymer 270 has solidified to finish the assembly and to provide the desired thermal contact and rigidity for a particular embodiment.

[0051]

[0066] With respect to Figure 9, a hybrid heat exchanger assembly 300 is provided that is similar in many respects to the hybrid heat exchanger assembly 16 of Figure 2. The hybrid heat exchanger assembly 300 includes a plurality of hybrid heat exchangers 302 connected in parallel to an inlet header 304 and an outlet header 306. The hybrid heat exchanger assembly 300 has a frame 308 that holds the hybrid heat exchangers 302 fixed to each other.

[0052]

[0067] Referring to Figure 10, a body 350 of a thermally conductive polymer is shown. The body 350 has an array of sheets 352 formed as a single piece, for example using additive manufacturing. The body 350 has an opening 354 that allows airflow to pass through the body 350 and a sheath portion 356 for receiving a fluid conduit, such as an extended portion of a serpentine tube connected via a return bend on the outside of the body 350. In one embodiment, the sheets 350 are connected via supports of the body 350 that extend between the sheets 350.

[0053]

[0068] With respect to Figure 11, a hybrid heat exchanger 400 is provided having an inlet tube 402, an outlet tube 404, and three tubes 406 connecting the inlet and outlet tubes 402 and 404. Each tube 406 includes a straight extension 412 and a return bend 414 connecting the straight extension 412. The hybrid heat exchanger 400 has a body 408 of a thermally conductive polymer that is thermally integrated with the tubes 406. The body 408 is thermally integrated with the straight extension 412 as well as the return bend 414. The return bend 414 is located inside the outer circumference 420 of the body 408. In one embodiment, the straight extension 412 and the return bend 414 are embedded in the body 408.

[0054]

[0069] The thermally conductive polymer body 410 has surface-reinforced features such as a chevron pattern 410. In one embodiment, the evaporative liquid is distributed in direction 411 onto the hybrid heat exchanger 400, and air moves across the hybrid heat exchanger 400 in a straight or reverse flow. The surface-reinforced features 410 create meandering paths for the evaporative liquid to move across the hybrid heat exchanger 411, which restrict air blow-through and improve heat transfer between the air and the evaporative liquid.

[0055]

[0070] With respect to Figure 12, a portion of the hybrid heat exchanger 450 is provided. The hybrid heat exchanger 450 has fluid conduits, for example, tubes 452, and a body 454 of a thermally conductive polymer integrated with the tubes 452. The tubes 452 have centerlines 453 with a distance 455 between them.

[0056]

[0071] The body 454 has chevrons 456 to influence the fluid flow across the outer surface 458 of the body 454. The chevrons 456 are arranged in alternating rows, with the first row extending at a positive angle 460 to the vertical and adjacent rows extending at a negative angle 460 to the vertical. The angled orientation of the chevrons 456 causes the fluid to move in direction 462 across the outer surface 458 of the body 454, taking a zigzag path across the outer surface 458, which improves heat exchange between the fluid and the body 454.

[0057]

[0072] With respect to Figure 13, the chevron 456 includes a raised portion 472 and a groove 474 formed by the wall portion 476 of the main body 454. The raised portion 472 has a peak 480, and the groove 474 includes a valley 482. The main body 454 has a height 484 from the peak to the valley, a distance 486 from the peak to the valley, and a distance 488 between sheath portions 490 of the main body 454, which may be selected for a particular embodiment. The sheath portions 490 extend around the entire cross-section of the tube 452 and are joined to the side walls 492 of the tube 452. In other embodiments, the sheath portions 490 may extend around less than the entire cross-section of the tube 452.

[0058]

[0073] With respect to Figure 14, a hybrid heat exchanger 500 is provided, including an inlet tube 502, an outlet tube 504, a circuit tube 506, and a body 508 made of a thermally conductive polymer. In Figure 15, the inlet tube 502 and the outlet tube 504 are removed to show that the circuit tube 506 includes a straight extension 510 and a return bend 512. The tube 506 extends through an opening 514 in a housing 516 for the body 508. The tube 506 may be, for example, a copper tube.

[0059]

[0074] With respect to Figure 16, a hybrid heat exchanger 550 is provided, which includes a fluid conduit, for example, a copper tube 552, and a body 554 of a thermally conductive polymer that is thermally integrated with the copper tube 552. The body 554 has a collar portion 556 and fins 560 that extend around an opening 558 of the body 554. The body 554 is 3D printed using a thermally conductive polymer filament. The copper tube 552 was advanced into the opening 558 after the body 554 was printed in order to assemble the hybrid heat exchanger 550. The outer diameter of the copper tube 552 became larger than the inner diameter of the opening 558 after the body 554 was 3D printed. Advancing the copper tube 552 into the opening 558 deformed the collar portion 556 of the body 554 around the opening 558, creating an interference fit that secures the body 554 to the copper tube 552. In an alternative approach, the copper tube 552 has an outer diameter smaller than the inner diameter of the opening 558 of the body 554, and the copper tube 552 is advanced into the opening 558, and the copper tube 552 is expanded to engage with the body 554 by applying a high-pressure fluid (e.g., water) to the inside of the copper tube 552.

[0060]

[0075] A variety of different materials can be used in the additive manufacturing process to form the hybrid heat exchangers described herein, and there are considerable possible variations in the performance / functionality of the thermally conductive polymer materials. For example, adding continuous copper wires may enhance thermal conductivity, and / or adding continuous nichrome wires may provide heating properties to the hybrid heat exchanger. Embedding phase-change materials into additive manufacturing filaments also allows various thermal energy storage designs to be used in accordance with these disclosures.

[0061]

[0076] The use of singular terms such as "a" and "an" is intended to cover both singular and plural unless otherwise stated herein or the context clearly contradicts this. The terms "comprising," "having," "including," and "containing" are interpreted as open-ended terms. The phrase "at least one of" is intended to be interpreted as disjunctive when used herein. For example, the phrase "at least one of A and B" is intended to encompass A, B, or both A and B.

[0062]

[0077] Although specific embodiments of the present invention have been illustrated and described, numerous variations and modifications will be conceivable to those skilled in the art, and it will be understood that the present invention is intended to cover all such variations and modifications that fall within the scope of the appended claims.

Claims

1. It is a hybrid heat exchanger, A metal serpentine tube having an inlet end portion for receiving process fluid, an outlet end portion, and a series of extensions and return bends for directing the process fluid from the inlet end portion toward the outlet end portion, A thermally conductive polymer body having an outer surface that is thermally integrated with the serpentine tube and in contact with a fluid, wherein the thermally conductive polymer body is configured to transfer heat between the metal serpentine tube and the fluid in contact with the outer surface of the thermally conductive polymer body, Surface strengthening features of the outer surface of the thermally conductive polymer body that affect the fluid flow on the outer surface of the thermally conductive polymer body and A hybrid heat exchanger, including one.

2. The extended portion of the metal serpentine tube has a total outer surface area, The outer surface of the thermally conductive polymer body has a surface area larger than the total outer surface area of ​​the extended portion of the metal serpentine tube. The hybrid heat exchanger according to claim 1.

3. The thermally conductive polymer body includes a sheath portion, The extended portion extends in the sheath portion, The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body includes a wall portion extending between adjacent sheath portions having the surface-reinforced feature.

4. Each of the extended portions of the metal serpentine tube has a length, The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body is in thermal contact with the extended portion of the metal serpentine tube for at least a large portion of the length of the extended portion.

5. Each of the extended portions has an outer surface and a cross-section perpendicular to the length, The hybrid heat exchanger according to claim 4, wherein the thermally conductive polymer body is in thermal contact with the outer surface of the extended portion around at least a large portion of the cross-section of the extended portion.

6. The hybrid heat exchanger according to claim 1, further comprising a thermally conductive paste for thermally connecting the thermally conductive polymer body and the metal serpentine tube.

7. At least one of the extended portions of the serpentine tube has a length and a cross-section perpendicular to that length, The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body has a sheath portion that extends around the entire cross-section of the serpentine tube for at least a portion of the length of the extended portion.

8. The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body has a thermal conductivity of at least 2 watts per meter-Kelvin.

9. The aforementioned thermally conductive polymer body, The matrix phase of the polymer material, At least one particle phase of metal and graphite and A hybrid heat exchanger according to claim 1, including the above.

10. The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body comprises a polymer material and a metal wire.

11. The extended portion of the metal serpentine tube is received by the thermally conductive polymer body. The hybrid heat exchanger according to claim 1, wherein the inlet and outlet portions of the metal serpentine tube are located outside the thermally conductive polymer body.

12. The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body is a plate.

13. The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body includes a portion of the thermally conductive polymer body assembled with the metal serpentine tube.

14. The hybrid heat exchanger according to claim 13, wherein the portion of the thermally conductive polymer body includes a collar that coats the outer surface of the extended portion of the metal serpentine tube.

15. The hybrid heat exchanger according to claim 1, wherein the metal serpentine tube has a single configuration.

16. A metal serpentine coil, Stainless steel tube, Aluminum tube, copper tube, and Carbon steel tube A hybrid heat exchanger according to claim 1, comprising at least one of the following.

17. The hybrid heat exchanger according to claim 1, wherein the metal serpentine tube is configured to withstand an operating pressure of at least 150 psig of the process fluid.

18. The hybrid heat exchanger according to claim 1, wherein the thermally conductive polymer body includes a filling portion that extends away from the metal serpentine tube.

19. The thermally conductive polymer body comprises a thermally conductive material and a phase change substance encapsulated within the thermally conductive material. The hybrid heat exchanger according to claim 1, wherein the phase-change material is configured to change its phase in response to heat transfer between the thermally conductive material and the phase-change material.

20. A heat exchanger system, An inlet header for receiving process fluid, Exit header and A plurality of fluid conduits of a first thermally conductive material, wherein each fluid conduit has an inlet end portion connected to the inlet header, an outlet end portion connected to the outlet header, and an intermediate portion along the fluid conduit between the inlet and outlet end portions, and the fluid conduits are configured to allow process fluid to flow from the inlet header to the outlet header. A body of a thermally conductive polymer having an outer surface that is different from the first thermally conductive material, Includes, A heat exchanger system in which the thermally conductive polymer body is in thermal contact with the intermediate portion of the fluid conduit and is configured to facilitate heat transfer between the process fluid and the fluid on the outer surface of the thermally conductive polymer body as the process fluid moves through the intermediate portion of the fluid conduit.

21. The heat exchanger system according to claim 20, wherein the thermally conductive polymer body is fixed to the intermediate portion of the fluid conduit and is spaced apart from the inlet and outlet headers.

22. Each of the fluid conduits has a length, The heat exchanger system according to claim 20, wherein at least one of the fluid conduits is embedded in the thermally conductive polymer body over at least a portion of the length of the at least one fluid conduit.

23. Each of the fluid conduits has a length, The heat exchanger system according to claim 20, wherein the thermally conductive polymer body is in thermal contact with the fluid conduit over at least a large portion of the length of the fluid conduit.

24. Each of the fluid conduits has an outer surface and a cross-section perpendicular to its length. The heat exchanger system according to claim 23, wherein the thermally conductive polymer body is in thermal contact with the outer surface of the fluid conduit around at least a large portion of the cross-section of the fluid conduit.

25. The hybrid heat exchanger according to claim 20, further comprising a thermally conductive paste for thermally connecting the thermally conductive polymer body and the fluid conduit.

26. The hybrid heat exchanger according to claim 20, wherein the thermally conductive polymer body has a thermal conductivity of at least 2 watts per meter-Kelvin.

27. A fan capable of operating to generate airflow over the thermally conductive polymer body, An evaporative liquid distribution system configured to distribute the fluid onto the outer surface of the thermally conductive polymer body, and A wastewater tank for collecting the fluid from the outer surface of the thermally conductive polymer body. The hybrid heat exchanger according to claim 20, further comprising:

28. The aforementioned thermally conductive polymer body comprises a polymer material, Graphite particles, metal particles, Metal wire, and Phase change substances The hybrid heat exchanger according to claim 20, comprising at least one of the following.

29. The aforementioned fluid conduit, Stainless steel tube, Aluminum tube, copper tube, and Carbon steel tube The hybrid heat exchanger according to claim 20, comprising at least one of the following.

30. The hybrid heat exchanger according to claim 20, wherein the fluid conduit is a microchannel.

31. A method for forming a hybrid heat exchanger, wherein the method is To provide a metal tube having an interior for receiving process fluids, Manufacturing a body of a thermally conductive polymer, wherein the body has an outer surface having surface-reinforced features to influence fluid flow on the outer surface of the body, and Thermally integrating the thermally conductive polymer body and the metal tube. A method that includes this.

32. The method according to claim 31, wherein the metal tube includes an inlet end portion, an outlet end portion, an extended portion, and at least one bend connecting the extended portion.

33. The aforementioned metal tube has an outer surface portion having a first surface area, Thermally integrating the thermally conductive polymer body and the metal tube includes fixing the outer surface portions of the thermally conductive polymer body and the metal tube. The method according to claim 31, wherein the thermally conductive polymer body includes an outer surface having a second surface area larger than the first surface area.

34. The method according to claim 31, wherein the production of the thermally conductive polymer body includes producing the thermally conductive polymer body using addition.

35. The method according to claim 34, wherein thermally integrating the thermally conductive polymer body and the metal tube includes adding the thermally conductive polymer in situ using the metal tube.

36. The production of the thermally conductive polymer body includes producing portions of the thermally conductive polymer body using additive manufacturing, The method according to claim 31, wherein thermally integrating the thermally conductive polymer body and the metal tube includes assembling the portion of the thermally conductive polymer body and the metal tube.

37. The method according to claim 31, wherein the production of the thermally conductive polymer body includes molding the thermally conductive polymer body.

38. The method according to claim 37, wherein thermally integrating the thermally conductive polymer body and the metal tube includes molding the thermally conductive polymer body with the metal tube in situ.

39. The method according to claim 31, wherein thermally integrating the thermally conductive polymer body includes positioning the thermally conductive paste between the thermally conductive polymer body and the metal tube.

40. The method according to claim 31, wherein thermally integrating the thermally conductive polymer body and the metal tube involves melting a portion of the thermally conductive polymer body, the melted portion of the thermally conductive polymer body being melted such that it fills the opening between the thermally conductive polymer body and the metal tube.

41. The method according to claim 31, wherein the production of the thermally conductive polymer body includes using an addition process of a polymer material into which discontinuous conductive particles are implanted.

42. The method according to claim 31, wherein the production of the thermally conductive polymer body is performed by using an addition process that includes forming beads comprising a metal thread and a polymer ring extending around the thread.

43. The aforementioned metal tube Stainless steel tube, Aluminum tube, copper tube, and Carbon steel tube The method according to claim 31, comprising at least one of the following.

44. Providing the aforementioned metal tubes includes providing at least three metal tubes. The method according to claim 31, wherein thermal integration of the thermally conductive polymer body and the metal tube includes integrating a single polymer body with the metal tube.

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