Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
  • F28F17/00—Removing ice or water from heat-exchange apparatus
  • F28F17/005—Means for draining condensates from heat exchangers, e.g. from evaporators
• • 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
  • F28D7/16—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 in parallel spaced relation
  • F28D7/1615—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 in parallel spaced relation the conduits being inside a casing and extending at an angle to the longitudinal axis of the casing; the conduits crossing the conduit for the other heat exchange medium
  • F28D7/1623—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 in parallel spaced relation the conduits being inside a casing and extending at an angle to the longitudinal axis of the casing; the conduits crossing the conduit for the other heat exchange medium with particular pattern of flow of the heat exchange media, e.g. change of flow direction
• • 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
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F27/00—Details of transformers or inductances, in general
  • H01F27/08—Cooling; Ventilating
  • H01F27/10—Liquid cooling
• • 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
  • F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
• • 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
  • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
  • F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
  • F28D2021/0028—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for cooling heat generating elements, e.g. for cooling electronic components or electric devices
  • F28D2021/0031—Radiators for recooling a coolant of cooling systems
• • 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
  • F28D21/00—Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
  • F28D2021/0019—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for
  • F28D2021/004—Other heat exchangers for particular applications; Heat exchange systems not otherwise provided for for engine or machine cooling systems
• • 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
  • F28D7/08—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 otherwise bent, e.g. in a serpentine or zig-zag
  • F28D7/082—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 otherwise bent, e.g. in a serpentine or zig-zag with serpentine or zig-zag configuration
  • F28D7/085—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 otherwise bent, e.g. in a serpentine or zig-zag with serpentine or zig-zag configuration in the form of parallel conduits coupled by bent portions

Definitions

• the present invention relates to non-evaporative or "dry" heat exchangers, particularly those used to cool marine power transformers, although the invention can be used in any environment or situation where "dry" cooling solutions are required or desired.
• the air used for cooling a transformer is passed over a series of coils through which water is circulated.
• the prior art dry transformer cooling coils consist of a series of straight double-walled tubes which terminate at each end in sealed chambered headers.
• the inner tubes of the straight tubes terminate in one chamber of the header, and the outer tubes terminate in a separate sealed chamber of the header. Cooling fluid is circulated through the inner tubes, and through the corresponding chambers of the headers at each end. Air is passed only over the tubes, and the chambered headers are located outside of the air stream. Any leak in one of the inner tubes is captured by its corresponding outer tube and travels to the separate header chamber at which the outer tubes terminate.
• any water from leaks in the inner tubes finds its way to an outer tube chamber in one of the headers.
• a leak detector is present at the bottom of each of the outer tube chambers to detect the presence of any water.
• the headers are sealed from one another and from the outside with gaskets, but can be opened for inspection.
• the disadvantages of this system include the material cost and complex construction of the chambered headers, with outer tubes terminating in one chamber and inner tubes terminating in another chamber.
• the chambered headers restrict the ability to efficiently circuit the coil. Summary of the Invention
• the present invention provides an elegant, safe and cost effective alternative to the prior art.
• a non- evaporative heat exchanger coil having a plurality of straight inner tubes connected by a plurality of return bends.
• the return bends allow fluid to move back and forth through the straight inner tubes of the coil.
• the return bends are preferably located outside of the air flow passing over the coil.
• the straight lengths of the inner tubes are each situated within a corresponding outer or "safety" tube.
• the outer tubes preferably terminate at or before the return bends that connect the inner tubes to one-another, but in any event, the ends of the outer tubes are located outside of the air flow path.
• the straight lengths of the heat exchange coil are double-walled or doubled tubed (inner tube within an outer tube), but the return bends are single-walled or single tubed.
• the inner surfaces of the outer tubes are dimpled, grooved, ribbed, or otherwise patterned to create both contact points and voids between the inner and outer tubes. Leaks occurring in the straight inner tubes are captured by the outer tubes and the leaking fluid will flow in the space between the inner and outer tubes, drip or flow out the end of the outer tube, outside of the air flow path, to be captured in a drip pan or leak detector box at the bottom of the coil housing. According to an embodiment of the invention, leaks occurring in the return bends will also be captured in drip pan or leak detector box.
• the bottom of the coil housing may be sloped so that only one leak detector is required.
• capturing leaks outside of the airstream allows a dry transformer to continue operating, notwithstanding the existence of a leak.
• this embodiment allows a ship to continue operating long enough to return to port for repair.
• no chambered headers are used, and neither the return bends nor the ends of the outer tubes need be contained in special water-tight housings.
• the return bends of the inner tubes are located outside of and separated from the air flow path over the coil.
• the ends of the outer tubes are located outside of and separated from the air flow path over the coil.
• the return bends and the ends of the outer tubes are located in a return bend box or other portion of the housing that is set off, but attached to, the primary housing.
• the return bend box need not be water-tight.
• fluid may also be introduced to and returned from the coil at one of the return bend boxes.
• the leak detectors may be located at the bottom of the return bend boxes.
• a sloping drain pan may be provided at the bottom of the coil so that water collected from leaks at one side of the coil drains to the other side of the coil for detection using a single leak detector.
• the transformer may be turned off, either automatically or manually, so the leak can be repaired.
• the space between the outer tubes and the inner tubes may be sealed or otherwise closed at one end of the coil, so that any leak in the inner tubes comes out only in the return bend box at the opposite end of the coil.
• the space between the inner and outer tubes remains open at the header end of the coil, and is sealed at the opposite end of the coil, so that water from leaks in the inner tubes travels down the inside of the outer tubes and into the return bend box at the header end, where it is detected by a leak detector. According to this embodiment, there is no need for a sloping drain pan.
• the coils may be situated in the bottom portion of a housing or "box" which is attached to a transformer transfer box.
• Fans located in the top portion of the housing draw air from the transfer box and force it down over the coils where it is cooled, and the cooled air then exits the housing and returns to the transfer box. Heat transfer is facilitated with the use of fins fixed to the outside surfaces of the outer/safety tubes.
• the coils can be an open system, in which water is drawn from a source, circulated through the coils and returned to the source, or a closed system in which the same water is circulated through the coils.
• a closed system the water warmed by the air passing over them will be cooled in a separate system before returning to the coils of the present invention.
• Figure 1A is a schematic of a section of heat exchange coil according to an embodiment of the invention.
• Figure IB is a representation of the principles of the invention, accomplished with double-walled/double tubed straight tubes connected by single- walled/single tubed return bends.
• Figure 2A is a front view schematic of a heat exchanger including a heat exchange coil according to an embodiment of the invention.
• Figure 2B is a side view schematic of the heat exchanger shown in Figure 2A.
• Figure 3 is a front perspective drawing of a transformer air cooling unit, including a heat exchanger according to an embodiment of the invention.
• Figure 4 is a rear perspective drawing of a transformer air cooling unit shown in Figure 3.
• Figure 5 is another rear perspective drawing of the transformer air cooling unit shown in Figure 3.
• FIG 1 A shows a heat exchange coil 10 according to an embodiment of the invention.
• Heat exchange coil 10 receives fluid from header 12 through connecting tube 14.
• Connecting tube 14 is connected to inner tube 16a. Fluid travels through the heat exchange coil through inner tubes 16a, 16b, and 16c, via return bends 18a and 18b.
• Inner tubes 16a, 16b, and 16c are expanded into outer tubes 20a, 20b, and 20c, respectively.
• the inner surfaces of outer tubes 20a, 20b, and 20c have dimples, ribs, or other surface features 21 to create both contact between and voids between the inner and outer tubes to allow the passage of fluid between them (see Figure IB).
• the outer surface of the inner tubes may have spacing features or be fitted with spacing devices to accomplish the same purpose.
• Fins 22 are fixed to the outside surfaces of the outer tubes to enhance heat exchange. The air flow is directed only over the center portion 24 of the coil. Return bends 18a, 18b, and the ends 26 of outer tubes 20a, 20b and 20c are located outside the air flow path.
• outer tubes are inserted into the fin matrix and expanded into the fins.
• the inner tubes are then inserted into the outer tubes and expanded to provide contact at the contact surfaces and voids at non-contact locations.
• the return bends may then be brazed to the inner tubes.
• the air flow path (and hence the transformer, or any other device into which the air is ultimately directed) is protected from water contamination resulting from leaks in the heat exchange coil, and leaks are quickly and easily detected, all without complicated nested and sealed chambered header arrangements.
• the space between the outer tubes and the inner tubes at one end of the coil may be brazed or otherwise sealed shut.
• water from leaks in the inner tubes falls out of the outer tubes only in the return bend box at the end of the coil that is opposite the end where the space between the inner and outer tubes is sealed shut.
• FIGS 2 A and 2B show schematics of a heat exchange unit 34 including a heat exchange coil according of the invention.
• Return bend boxes 30a and 30b are situated outside of the primary housing of heat exchange unit, and contain the return bends (not shown) at both ends of the inner tubes (also not shown).
• Fins 22 are shown, which as described above, are fixed to the outside surfaces of the outer tubes of the heat exchange coil.
• Header 12 includes fluid inlet/outlets 32.
• drain pan 28 may be provided with a slope between the return bend boxes so that water from leaks collected in one return bend box is made to travel to the other side of the coil where it can be detected with a leak detector.
• FIGs 3-5 show different views of a transformer air cooling unit 36, including a heat exchanger according to an embodiment of the invention.
• Transformer air cooling unit 36 includes fan box 38, resting on top of heat exchange unit 34.
• Fans inside fan box 38 pull air from a transformer transfer unit (not shown) through louvers 39 and direct air down through heat exchange unit 34.
• Air passes over the tubes (not visible in Figs 3-5) and fins 22, to exit the bottom of the unit.
• Return bends and the ends of outer safety tubes are contained in return bend boxes 30a and 30b, outside of the air flow path, and the air flow path is preferably contained within heat exchange unit 34.
• Water enters one of fluid inlet/outlets 32 and exits through the other according to desired water flow valving/settings.
• Leak detector 40 detects the presence of water in the bottom of return bend box 30a.

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

Priority Applications (1)

Applications Claiming Priority (2)

Publications (3)

Family

ID=52440964

Family Applications (1)

Country Status (4)

Family Cites Families (9)

• 2013
  • 2013-04-25 ES ES13782020T patent/ES2912555T3/es active Active
  • 2013-04-25 EP EP13782020.5A patent/EP2841863B1/de active Active
  • 2013-04-25 DK DK13782020.5T patent/DK2841863T3/da active
  • 2013-04-25 PL PL13782020T patent/PL2841863T3/pl unknown

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