Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/02—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers
  • B21D53/06—Making other particular articles heat exchangers or parts thereof, e.g. radiators, condensers fins, headers of metal tubes
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D7/10—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically
  • F28D7/106—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged one within the other, e.g. concentrically consisting of two coaxial conduits or modules of two coaxial conduits
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/003—Multiple wall conduits, e.g. for leak detection
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/02—Tubular elements of cross-section which is non-circular
  • F28F1/022—Tubular elements of cross-section which is non-circular with multiple channels
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F1/00—Tubular elements; Assemblies of tubular elements
  • F28F1/02—Tubular elements of cross-section which is non-circular
  • F28F1/025—Tubular elements of cross-section which is non-circular with variable shape, e.g. with modified tube ends, with different geometrical features
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/49—Method of mechanical manufacture
  • Y10T29/4935—Heat exchanger or boiler making
  • Y10T29/49361—Tube inside tube

Definitions

• the following disclosure relates generally to fluid conduits for use in heat exchangers and, more particularly, to dual wall tubing for use in heat exchangers.
• Copper tubing has many uses in heating, ventilation, and air conditioning (HVAC) applications.
• HVAC heating, ventilation, and air conditioning
• Various arrangements of tubing have been used in heat exchangers to hold at least one of the fluids taking part in the heat transfer. These tubing arrangements may leak causing contamination between fluids: if the tubing carrying one of the fluids ruptures the fluids within and without the tube may be mixed.
• Dual wall heat exchanger conduits are commonly used in heat pump water heaters to avoid leakages of refrigerant and oils into a potable water supply.
• Conventional dual wall heat exchanger conduits have utilized a first tube inserted into and pressed against a second tube. Either the first or the second tubes can have protrusions which create a leak path between the tubes. These protrusions can lead to high thermal contact resistance between the tubes, rendering the heat exchanger relatively inefficient.
• Some heat exchanger conduits have fluids flowing through the space between the inner tube and the barrier tube. This arrangement poses a risk of fluid cross-contamination in the event of a tube rupture.
• These heat exchanger conduits further utilize a tapered structure, such that the exchangers are increasingly flattened from end to end in a stepwise or continuous manner to compensate for different fluid properties in warm versus cold regions. This tapering requires more manufacturing complexity than if the exchanger was of a continuous height along all or most of its length.
• Figure 1A is a cross-sectional end view of a heat exchanger conduit having a circular barrier tube with a plurality of circular inner tubes nested therein, in accordance with an embodiment of the disclosure.
• Figure 1 B is a cross-sectional end view of the heat exchanger conduit of Figure 1A after it has been flattened in accordance with an embodiment of the disclosure.
• Figure 1 C is a cross-sectional end view of a flattened heat exchanger conduit configured in accordance with another embodiment of the disclosure.
• Figures 2A-2C are a series of end views illustrating various cross- sections of the heat exchanger conduit of Figure 1 B at various points along its length.
• Figure 3 is a cross-sectional end view of the heat exchanger conduit of Figure 1 B with a fluid surrounding a barrier tube.
• Figure 4 is an isometric view of a bent heat exchanger conduit configured in accordance with an embodiment of the disclosure.
• Figure 5 is an isometric view of a bent heat exchanger conduit configured in accordance with another embodiment of the disclosure.
• Figure 6 is an isometric view of a bent heat exchanger conduit configured in accordance with another embodiment of the disclosure.
• Figure 7 is a top view of a heat exchanger conduit having alternating lengths of straight flattened sections and rounded bent sections configured in accordance with an embodiment of the disclosure.
• Figure 8 is a cross-sectional end view of a heat exchanger conduit configured in accordance with another embodiment of the disclosure.
• Figure 9 is an isometric view of a heat exchanger having a corrugated outer sleeve configured in accordance with another embodiment of the disclosure.
• Figure 10 is a cross-sectional end view of a flattened heat exchanger conduit having a plurality of grooved inner tubes configured in accordance with another embodiment of the disclosure.
• Figure 1 1 is a cross-sectional end view of a flattened heat exchanger conduit having a dimpled barrier tube in accordance with a further embodiment of the disclosure.
• Figure 12 is a cross-sectional end view of a flattened heat exchanger conduit having a barrier tube with a plurality of fins configured in accordance with another embodiment of the disclosure.
• Figure 13A is a cross-sectional end view of a heat exchanger conduit having a circular barrier tube with a plurality of pre-flattened inner tubes nested therein
• Figure 13B is a cross-sectional end view of the heat exchanger conduit of Figure 13A after the barrier tube has been formed around the inner tubes in accordance with another embodiment of the disclosure.
• Figure 14 is a cross-sectional end view of a heat exchanger conduit having a plurality of inner tubes with inserts positioned therein in accordance with another embodiment of the disclosure.
• Figure 15 is a cross-sectional end view of a heat exchanger conduit having a turbulator and a plurality of inner tubes positioned in an outer sleeve in accordance with yet another embodiment of the disclosure.
• the present disclosure describes various embodiments of a tubing assembly, such as a heat exchanger conduit, having an outer barrier tube with a plurality of fluid-carrying inner tubes nested therein.
• the nested tube heat exchanger conduit can be manufactured by inserting two or more inner tubes into a circular or at least partially circular barrier tube and at least partially flattening at least some length of the assembly.
• the heat exchanger conduit can include one or more void spaces within the barrier tube and adjacent to the inner tubes which serve to contain any leaks in the inner tubes and vent any leaks to the atmosphere.
• Figure 1A is a cross-sectional end view of a nested multi-tube heat exchanger conduit 100 having an outer barrier tube 110 with a plurality of fluid- carrying inner tubes 1 12 nested therein.
• the outer barrier tube 1 10 is referred to hereinafter as the "barrier tube 1 10.”
• Figure 1 B is a cross- sectional end view of the heat exchanger conduit 100 after it has been flattened in accordance with an embodiment of the disclosure.
• the inner tubes 1 12 and barrier tube 1 10 can be made of various materials known in the art.
• one or more of the tubes 1 10, 1 12 can be made of copper, copper alloy, aluminum, stainless steel, etc.
• the inner tubes 1 12 and the barrier tube 1 10 can be made of different materials, while in further embodiments the inner tubes 1 12 and barrier tubes 1 10 can be made of the same material. In yet another embodiment, the inner tube 1 12 and/or the barrier tube 1 10 can have a grooved and/or textured surface.
• the inner tubes 112 and the barrier tube 1 10 can have various sizes in accordance with the present disclosure depending on the intended application.
• the barrier tube 110 can have an outer diameter Di ranging from about 0.3 inch to about 1 .4 inches, or from about 0.5 inch to about 0.9 inch, prior to flattening and the inner tubes 1 12 can have a diameter D 2 ranging from about 0.06 inch to about 0.8 inch, or from about 0.1 inch to about 0.4 inch, prior to flattening.
• the inner tubes 1 12 and/or barrier tube 1 10 can have diameters Di, D 2 that fall outside of these ranges.
• all or some of the inner tubes 1 12 may each have different diameters.
• both the barrier tube 1 10 and the inner tubes 1 12 take on an oval shape, as illustrated in Figure 1 B.
• the ratio between the diameter Di of the barrier tube 1 10 and a flattened height Hi of the barrier tube 1 10 ranges from about 2:1 to about 3:1 .
• the ratio between the diameter D 2 of the individual inner tubes 1 12 and a flattened height H 2 of the inner tubes 1 12 ranges from about 1.4:1 to about 2.4:1 .
• the barrier tube 1 10 and inner tubes 1 12 can have ratios between their diameters Di, D 2 and their flattened heights Hi, H 2 that fall outside of these ranges.
• the inner tubes 1 12 and the barrier tube 110 can have wall thicknesses Ti , T 2 respectively, ranging from about 0.008 inch to about 0.045 inch, or from about 0.016 inch to about 0.032 inch.
• the barrier tube thickness Ti and the inner tube thickness T 2 can be the same, while in further embodiments the tube thicknesses ⁇ , T 2 can be different.
• the length of the heat exchanger conduit 100 can vary in different embodiments of the invention. In some embodiments, for example, the length of the heat exchanger conduit 100 can range from about 1 foot to about 100 feet, or about 3 feet to about 40 feet, depending on the intended use of the heat exchanger conduit 100.
• the heat exchanger conduit 100 may be about 10 feet or may be multiple sections of about 3 feet.
• the tube may be longer, up to about 40 feet.
• the heat exchanger conduit 100 can be manufactured in other lengths, depending on the intended application of the conduit 100.
• the foregoing dimensions of the nested tube heat exchanger conduit 100 are merely illustrative of various embodiments of heat exchanger conduits configured in accordance with the present disclosure. Accordingly, other embodiments of the present disclosure can include flattened tubes having different diameters, heights, thicknesses, shapes, lengths, etc. depending on the particular application of use and/or a number of different variables including, for example, the wall thickness of the tube, the outer diameter of the tube, the amount of flattening, etc. Therefore, those of ordinary skill in the art will appreciate that various embodiments of the invention described herein are not necessarily limited to any particular tube configuration, but extend to all such configurations falling within the scope of the present disclosure.
• the heat exchanger conduit 100 In the illustrated heat exchanger conduit 100, three inner tubes 112 are nested within the barrier tube 110. In other embodiments, the heat exchanger conduit 100 can include more or fewer inner tubes 112.
• the heat exchanger conduit 101 in Figure 1 C for example, has six inner tubes 112 nested within a barrier tube 1 11 .
• the inner tubes 1 12 can be placed within the barrier tube 1 10 using various methods.
• the barrier tube 1 10 can be partially pre-flattened to a height that is between its original diameter Di and its final flattened height Hi .
• the inner tubes 112 can be fed inside the barrier tube 110.
• the entire heat exchanger conduit 100 can be flattened.
• the inner tubes 112 may be fed into the barrier tube 1 10 prior to flattening the barrier tube.
• the barrier tube 1 10 flattened onto the inner tubes 1 12 through the use of a suitable "sinking" process.
• the barrier tube 1 10 may be formed around the inner tubes 1 12 by stretch reducing or twisting the barrier tube 1 10 through the application of the Poisson effect. Stretch reducing and/or twisting the barrier tube 1 10 involves increasing the length of the barrier tube 110 by stretching the barrier tube 1 10 longitudinally, thereby reducing the diameter of barrier tube 1 10 until the barrier tube 1 10 is flattened onto the inner tubes 1 12.
• a number of suitable methods known in the art can be used to flatten the heat exchanger conduit 100.
• the heat exchanger conduit 100 is compressed to the desired height Hi using a vice or press.
• the heat exchanger conduit 100 is flattened using opposing rollers.
• the pressure drop of the inner tubes 112 can be measured after flattening to ensure that the tubes 1 12 remain open along their entire length.
• the heat exchanger conduit 100 increases the surface contact between adjacent inner tubes 112 and between the inner tubes 1 12 and the barrier tube 1 10. This increased surface contact lowers the heat transfer resistance between fluids inside the inner tubes 1 12 and outside the barrier tube 1 10. Additionally, the flattening operation reduces the hydraulic diameter of the inner tube, which leads to high convective heat transfer rates and reduced refrigerant inventory.
• the heat exchanger conduit 100 can be twisted. The twisting aids in forcing the inner tubes 1 12 and barrier tube 1 10 together to increase conductive heat transfer among the tubes.
• the heat exchanger conduit 100 When the heat exchanger conduit 100 is flattened, one or more voids 122 are created adjacent to and between the inner tubes 1 12.
• the inner tubes 1 12 contact each other so that the voids 122 are not in fluid communication with each other (i.e. the voids are isolated from each other).
• the voids 122 may take on various shapes. In one embodiment, for example, at least one of the voids 122 can extend the entire length of the heat exchanger conduit 100. In other embodiments, one or more of the voids 122 can extend only part of the length of the heat exchanger conduit 100.
• FIGS 2A-2C are a series of cross-sectional end views illustrating cross-sections of the heat exchanger conduit 100 of Figure 1 B at various points along the length of the heat exchanger conduit 100.
• the tubes 1 10, 1 12 are flattened along only a middle portion of the length of the heat exchanger conduit 100.
• end portions 240 of the heat exchanger conduit 100 are not flattened but are instead left in a circular configuration.
• end portions 240 circular allows the tubes 1 12 to be easily joined to a single tube for carrying fluid to other stages in the corresponding heat exchanger. Furthermore, having a circular end portion 240 allows the barrier tube 110 to be connected to other tubes (not shown) by solder or other means using conventional circular end caps or other end fittings.
• the heat exchanger conduit can have a flattened, flared, or other cross-sectional shape along its end portions and the heat exchanger conduit 100 can be connected to other tubes using specialized processes or non-circular fittings or end caps.
• FIG. 3 is a cross-sectional end view of the heat exchanger conduit 100 with a fluid space 324 surrounding the barrier tube 1 10.
• the heat exchanger conduit 100 transfers heat between a first fluid 330 carried within the ovalized inner carrier tubes 1 12 and a second fluid 332 carried in the fluid space 324 external to the barrier tube 1 10.
• the fluid space 324 may be contained by an outer sleeve 302 and configured to be a heat exchanger.
• This flattened tube configuration is highly effective for heat transfer due to the low heat transfer resistance between the fluid transporting tubes 112 and the barrier tube 110. Heat is transferred through the walls of the inner 112 and barrier tubes 1 10, from the warmer of the first 330 or second 332 fluids to the cooler of the fluids.
• first fluid 330 and second fluid 332 can be any one of numerous fluids.
• first fluid 330 can be a working fluid, such as a refrigerant, while second fluid 332 can be potable water.
• the first fluid 330 may be any working fluid such as, ammonia, propane, carbon dioxide, steam, or water.
• first fluid 330 is a working fluid and second fluid 332 is air.
• the first fluid 330 is potable water and the second fluid 332 is a working fluid and/or a gas.
• the first fluid 330 and the second fluid 332 are the same fluids.
• heat exchanger conduits 100 described herein have several applications for use as heat exchangers.
• a heat pump water heater for instance, water is heated using hot refrigerant gases from a refrigerant compressor discharge.
• High pressure refrigerant or a refrigerant and oil mixture flows inside the inner tubes 1 12.
• the barrier tube 110 is made of a material that is compatible with potable water such as copper.
• the inner tubes 1 12 must be made of a material and material thickness combination that can withstand the pressure and temperatures of the refrigerant.
• both tubes from copper or a copper alloy is a highly- preferred embodiment, as copper has a high conductivity, is easily formed, and can easily be joined to the other fluid system connections.
• the higher pressure can cause the inner tubes 1 12 to have a tendency to round and thus press out on the barrier tube 1 10.
• the illustrated configuration has the advantage that when the inner tubes 1 12 are pressurized, they can press into the barrier tube 1 10, increasing contact and reducing any resistance to heat transfer.
• the barrier tube 1 10 can provide some resistance to this rounding tendency, which can help keep the ovalized shape of the inner tubes 1 12.
• the fluid 330 flowing in the inner tubes 1 12 can be an engine/cooling refrigerant or bottoming cycle working fluid.
• the fluid 332 in the fluid space 324 outside the barrier tube 1 10 can be air or an air/exhaust gas mixture.
• aluminum or stainless steel may be a preferred material for the inner tubes 1 12 and/or barrier tube 1 10.
• the fluid 330 flowing inside the inner tubes 1 12 can be potable water, a bottoming cycle working fluid, or emission reduction fluid.
• the fluid 332 flowing in the fluid space 324 outside the barrier tube 1 10 can be exhaust gas.
• the heat exchanger conduit may be used as a solar water heater with potable water as the outer fluid 332 flowing in fluid space 324 and a heat transfer fluid as the inner fluid 330 flowing in the inner tubes 1 12.
• the heat exchanger may again be used as a solar water heater, but with potable water as the inner fluid 330 and a heat transfer fluid as the outer fluid 332.
• the void space 122 serves as a leak containment space and the two heat transfer fluids 330, 332 do not mix.
• This leak-capturing feature is important in any use of the heat exchanger conduit where it would be problematic or dangerous to have the first 330 and second 332 fluids mix.
• refrigerant for example, having an uncontained rupture in a refrigerant tube could be toxic to the water supply.
• the same threat arises when potable water is heated using exhaust gases where acids and particulate from the exhaust gas could be toxic to the water.
• Heat exchange systems on engines or fuel cells also must maintain fluids apart from each other. Otherwise, a contaminated fluid in the power-producing unit could result in toxins in the exhaust or cause the power-producing unit to malfunction.
• FIGS 4-7 are views of heat exchanger conduits having flattened tubes configured in accordance with embodiments of the present disclosure.
• the heat exchanger conduits 400, 500, 600 can be coiled (i.e. formed into one or more loops), bended, twisted, or otherwise shaped or deformed (hereinafter, collectively referred to as "bended"). Bending the heat exchanger conduits 400, 500, 600 can have advantages in certain applications. First, bending promotes stretching of the metal and can allow for greater contact between the inner 112 and barrier 110 tubes.
• FIG. 7 illustrates an embodiment of the invention having alternating lengths of straight flattened sections and circular bent sections.
• the ability to bend the heat exchanger conduit can allow the design engineer to better use the allowed space and to locate fluid inlet/outlet connections where desired.
• FIG. 8 is a cross-sectional end view of a heat exchanger conduit 800 in accordance with an embodiment of the invention.
• the inner tubes 812 can remain in a circular configuration and the barrier tube 810 can be fitted and/or flattened around the inner tubes 812.
• the inner tubes 812 can have individual diameters D3 and wall thicknesses T3 that are similar to the diameters D 2 and thickness T 2 described above with reference to the inner tubes 1 12 in Figure 1 .
• the inner tubes 812 can have a greater or lesser wall thickness T 3 and a greater or lesser diameter D 3 .
• the inner tubes 812 can have a diameter D3 of about 0.375 inch.
• the inner 812 and/or barrier 810 tubes can have a grooved or other texture.
• one or more voids 822 are created adjacent to and between the inner tubes 812 when the heat exchanger conduit 800 is flattened.
• the inner tubes 812 contact each other and the voids 822 are not in fluid communication with each other.
• the voids 822 may take on various shapes. In one embodiment, for example, at least one of the voids 822 can extend the entire length of the heat exchanger conduit 800. In other embodiments, one or more voids 822 can extend only part of the length of the heat exchanger conduit 800. In still further embodiments, the voids 822 can have different shapes along the length of the heat exchanger conduit 800.
• FIG. 9 is an isometric view of a heat exchanger 900 having a barrier tube 910 and a plurality of inner tubes 912 flattened and formed into a coil in accordance with another embodiment of the present disclosure.
• a corrugated outer sleeve 902 having a circular cross section is fitted over the barrier tube 910.
• the cross section of outer sleeve 902 may have other shapes such as, for example, an oval.
• the corrugated outer sleeve 902 can be made from a suitable material for the application and may also be dimpled or flattened.
• the outer sleeve 902 may be made from other materials suitable for the transport of, for example, potable water.
• End fittings 940 and 942 are attached to opposite ends of the outer sleeve 902, fluidly sealing the outer sleeve 902 to the barrier tube 910.
• the end fittings 940 and 942 each have a fluid inlet and/or outlet.
• a first fluid e.g. a working fluid such as a refrigerant
• a second fluid e.g. a fluid to be cooled or heated by the working fluid
• Forming the heat exchanger 900 into a coil can induce secondary flows in the first fluid flowing through the inner tubes 912 and in the second fluid flowing through the fluid space between the barrier tube 910 and the outer sleeve 902. Secondary flows can occur when a fluid flows through a coiled tube and can be caused by a pressure gradient between the inner wall and outer wall of the coiled tube. Secondary flows can cause increased turbulence in the first and second fluid flows, thereby increasing heat transfer between the two fluids.
• FIGS 10-12 are cross-sectional end views of heat exchanger conduits 1000, 1 100 & 1200, respectively, having flattened tubes configured in accordance with embodiments of the present disclosure.
• the heat exchanger conduits 1000, 1 100, and 1200 can be configured to increase fluid turbulence in a plurality of inner tubes 1012 and/or in a fluid space 1024, external to a barrier tube 1010, thereby increasing heat transfer between a first fluid 1030 flowing through the inner tubes 1012 and a second fluid 1032 flowing through the fluid space 1024.
• the fluid space 1024 may be enclosed by an outer sleeve 1002.
• Figure 10 illustrates one embodiment in which grooves 1014 are formed on an interior surface portion of the inner tubes 1012.
• the grooves 1014 may be formed on an exterior surface portion of barrier tube 1010 and/or on an interior surface portion of the sleeve 1002.
• Figure 1 1 illustrates another embodiment in which dimples 11 16 are created in a sidewall of barrier tube 1010 that at least partially protrude into a sidewall of one or more of the inner tubes 1012. Creating one or more dimples can allow for increased surface contact between the inner tubes 1012 and the barrier tube 1010, thereby facilitating greater heat transfer between the first fluid 1030 and the second fluid 1032.
• Figure 12 illustrates a further embodiment in which one or more fins 1218 are formed on an exterior surface of barrier tube 1010. The fins 1218 can increase turbulence of the outer fluid 1032, again increasing heat transfer between the working fluid 1030 and the outer fluid 1030.
• the fins may be formed using various suitable methods known in the art, such as welding, bonding, skiving, etc.
• Figure 13A is a cross-sectional end view of a heat exchanger conduit 1300 having a barrier tube 1310 (e.g. a circular barrier tube) with a plurality of pre- flattened inner tubes 1312 nested therein
• Figure 13B is a cross-sectional end view of a heat exchanger 1301 after the barrier tube 1310 is formed around the inner tubes 1312.
• the barrier tube 1310 can be formed around the inner tubes 1312 using various suitable methods known in the art, such as rolling, shrinking, twisting, etc.
• a working fluid 1330 flows through the inner tubes 1312 and an outer fluid 1332 flows through a fluid space 1324 external to the barrier tube 1310.
• the fluid space 1324 may be contained by an outer sleeve 1302.
• the resulting conduit in a straight, coiled, or twisted configuration, exposes increased external surface area to the outer fluid 1332 flowing through the fluid space 1324 and can also cause increased turbulence in the outer fluid 1332, thereby allowing increased heat transfer between inner fluid 1330 and outer fluid 1332.
• FIG. 14 is a cross-sectional end view of a heat exchanger conduit 1400 having a barrier tube 1410 and a plurality of flattened inner tubes 1412 nested therein, in accordance with another embodiment of the present disclosure.
• an insert 1413 is disposed in each of the inner tubes 1412, and each insert 1413 includes a cavity 1414 sealed from the inner fluid 1430.
• the inserts may be a solid rod, a bar, and/or a corrugated strip.
• the use of the inserts 1413 in the interiors of the inner tubes 1412 decreases the hydraulic diameters of the inner tubes 1412, thereby allowing increased heat transfer between a first fluid 1430 and a second fluid 1432 flowing through a fluid space 1424.
• the insert 1413 also serves as an impediment to further flattening of the inner tubes 1412, such that when pressure is applied to the barrier tube 1410 there is increased thermal contact between the barrier tube 1410 and inner tubes 1412.
• the fluid space 1424 may be contained within an outer sleeve 1402.
• Figure 15 is a cross-sectional end view of a heat exchanger conduit 1500 having a plurality of flattened tubes 1512, a corresponding barrier tube 1510, and two turbulators 1506 in an outer sleeve 1502, in accordance with one embodiment of the present disclosure.
• a first fluid 1530 flows through the inner tubes 1512 and a second fluid 1532 flows through a fluid space 1524.
• the turbulators 1506 are located in the fluid space 1524.
• the turbulators 1506 can be springs, twisted tape, star beads, or other turbulators known in the art.
• the turbulators 1506 in the fluid space 1524 can induce increased turbulence in the outer fluid 1532, thereby allowing increased heat transfer between the inner fluid 1530 and the outer fluid 1532.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Geometry (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

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• 2011
  • 2011-07-28 US US13/193,525 patent/US20120055660A1/en not_active Abandoned
  • 2011-08-31 WO PCT/US2011/050045 patent/WO2012031010A1/en active Application Filing
  • 2011-08-31 EP EP11822595.2A patent/EP2612097A4/de not_active Withdrawn
  • 2011-08-31 CA CA2808004A patent/CA2808004A1/en not_active Abandoned

Patent Citations (7)

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