US3672020A - Method of making a heat pipe having an easily contaminated internal wetting surface - Google Patents

Method of making a heat pipe having an easily contaminated internal wetting surface Download PDF

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Publication number
US3672020A
US3672020A US38323A US3672020DA US3672020A US 3672020 A US3672020 A US 3672020A US 38323 A US38323 A US 38323A US 3672020D A US3672020D A US 3672020DA US 3672020 A US3672020 A US 3672020A
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US
United States
Prior art keywords
heat pipe
working fluid
capillary structure
metal
soluble
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Expired - Lifetime
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US38323A
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English (en)
Inventor
Robert Alfred Freggens
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RCA Corp
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RCA Corp
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Publication date
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Publication of US3672020A publication Critical patent/US3672020A/en
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
    • F16L58/00—Protection of pipes or pipe fittings against corrosion or incrustation
    • F16L58/02—Protection of pipes or pipe fittings against corrosion or incrustation by means of internal or external coatings
    • 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
    • F28D15/02—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 in which the medium condenses and evaporates, e.g. heat pipes
    • F28D15/04—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 in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
    • F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
    • 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
    • Y10T29/49353—Heat pipe device making
    • 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
    • Y10T29/4981—Utilizing transitory attached element or associated separate material
    • Y10T29/49812—Temporary protective coating, impregnation, or cast layer
    • 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
    • Y10T29/49826—Assembling or joining
    • Y10T29/49885—Assembling or joining with coating before or during assembling

Definitions

  • a type of heat pipe having an easily contaminated internal wetting surface is a heat pipe employing a mercury metal working fluid, a stainless steel capillary structure, and a stainless steel envelope inner wall.
  • Heat pipes of this type operate unsatisfactorily because the stainless steel surfaces tend to become. oxidized during heat pipe construction. Oxidized or un-clean" surfaces are poorly wetted by the working fluid, reducing the capillary pumping pressure from that obtainable with clean" surfaces.
  • Previous heat pipes have employed scavengers" to remove the oxides from the stainless from stainless steel surface.
  • active metals such as calcium, magnesium, and sodium have been added to the mercury metal working fluid prior to evacuating the heat pipe.
  • this method results in the formation of compounds, such as Na O,-Fe,O which are insoluble in the working fluid. These compounds, in turn, tend to block or plug up the small pores of the capillary structure, whereby the capillary pumping is again inhibited.
  • the operating life of the heat pipe may be reduced by the erosion of the envelope by the working fluid during heat pipe operation.
  • the novel method applies to making a heat pipe comprising a sealed'envelope containing at least one surface that is wettable by a working fluid, the surface being easily contaminated so as to be poorly wetted by the working fluid.
  • the novel method comprises cleaning the surface to remove contaminents therefrom and then coating the cleaned surface with a material that is soluble in the working fluid at an operating temperature of the heat pipe.
  • the heat pipe is then assembled, evacuated, and sealed.
  • the cleaned surface By coating the cleaned surface, it is protected against contamination, particularly by oxidation.
  • the protective coating By using a .coating material that is soluble in the working fluid, the protective coating can be removed by the-working fluid after the heat pipe is sealed. Scavengers may be omitted from the working fluid, thus obviating the formation of undesirable compounds in the heat pipe.
  • Heat pipes made by the novel method operate longer and more efficiently than do heat pipes made by previous methods. Also, coatingmaterial dissolved in the working fluid reduces the erosive action of the working fluid on the envelope during operation.
  • FIG. 1 is a longitudinal sectional view of a heat pipe made by the novel method.
  • FIG. 2 is a sectional view of an end portion of the heat pipe of FIG. 1.
  • a heat pipe as shown in FIG. 1, comprises an envelope 11 consisting of a long, thin tubular member 13 made of stainless steel.
  • the tubular member 13 is sealed at one end to a stainless steel end cap 15 and at the other end to a stainless steel exhaust cap 17 having an exhaust tubulation l9.
  • the envelope 11 also contains a mercury metal working fluid in contact with and saturating the capillary structure 23.
  • the envelope parts l3, l5, and I7 and the capillary structure 23 are each cleaned chemiproduce thin protective coatings thereon. As shown in FIG. 2, a coating 25 is produced on each of the inner walls of the envelope 11, and a coating 27 is produced on the surface of the capillary structure 23.
  • the envelope parts l3, l5, and 17 and the capillary structure 23 are then re-fired at a lower temperature, about 800 C., to remove contaminents which may have entered the clean stainless steel surfaces or been codeposited during the plating process.
  • the capillary structure 23 is inserted within the tubular member 13, and the end cap 15 is electron-beam welded to one end of the tubular member 13.
  • the mercury metal working fluid is then added, under an inert atmosphere of argon, to the end-capped tubular member 13 at the opposite, open end thereof.
  • the open end of the tubular member 13 is, in turn, electron-beam welded to the exhaust cap 17, the exhaust tubulation 19 of which is connected to a suitable vacuum exhaust system (not shown).
  • the nickel coatings 25 and 27 are insoluble in the mercury metal working fluid.
  • the assembled heat pipe is then evacuated at an elevated temperature, about 400 C., to further clean the system. Since the operating temperature range of the heat pipe is between about 250 C.
  • portions of the nickel coatings 25 and 27 are dissolved by the mercury metal working fluid during the evacuating step.
  • mercury vapor is contained in the envelope 11 by heating the exhaust tubulation to about 800 C.
  • the exhaust tubulation 19 is tipped off to produce a sealed, vacuum-tight envelope 1 1.
  • the heat pipe may be operated by suitably heating either end region thereof to a temperature within the range between about 250 C. and about 450 C.
  • the region adjacent the end cap l5-tubular member 13 seal is usually chosen as the heat input or evaporator region of the heat pipe; and the region adjacent the exhaust cap l7-tubular member 13 seal is usually the heat output or condenser regionof the heat pipe.
  • the input heat thereto is absorbed by the mercury metal working fluid, which is then evaporated from the capillary structure 23.
  • the vapor thus formed enters the hollow volume of the heat pipe and flows to the cooler, condenser region of the heat pipe.
  • the vapor In the condenser region, the vapor is condensed, and the condensate thus formed is absorbed by the capillary structure 23.
  • the capillary structure 23 then "pumps" the condensate back to the evaporator region, and the cycle is repeated.
  • the pumping capability of the capillary structure 23 should be as great as possically and fired in a reducing atmosphere at about 900 C. to i ble. That is, the capillary pumping pressure should be as high as possible.
  • the capillary pumping pressure is, in turn, related to the extent to which the capillary structure 23 is wetted by the mercury metal working fluid. At the start of the heat pipe operation as described above, the capillary pumping pressure is relatively low, because the nickel-plated capillary structure is not well wetted by the working fluid. It will be recalled that the nickel coatings 25 and 27 are only partially dissolved by the mercury metal working fluid during the evacuating step.
  • the coating 25 and 27 are thick enough, that is, the amount of coating material is sufiicient, to saturate the mercury metal working fluid with the dissolved nickel. Where the amount of coating material is insufficient to saturate the with some nickel, thereby limiting the capillary pumping pressure in the heat pipe.
  • a typical heat pipe made by the novel method described above has an overall length of 14.27 inches, an outer diameter of 0.438 inch, and a wall thickness of 0.020 inch.
  • the envelope 11 is made of type 304 stainless steel, and the capillary structure 23 comprises 2.25 wraps of 60x60 stainless steel mesh screen.
  • the nickel coatings 25 and 27 each have an initial thickness of about 0.0002 inch.
  • a heat pipe as described above was operated at a temperature of about 325 C., with a thermal transfer of about 340 watts, for greater than 25,000 hours.
  • the performance of the heat pipe was studied in terms of the wetting angle between the working fluid and the capillary structure 23, as calculated from the equation P being the capillary pumping pressure, r being the pore radius of the capillary structure, ,8 being the surface tension of the working fluid, and 1: being the wetting angle between the working fluid and the capillary structure.
  • d was about 72; after 400 hours, was about 63; and after 4,500 hours, (b was about 57. Since it had been shown elsewhere (see, for example, J. J.
  • the heat pipes may employ re-entrant, annular, angular, and flat-plate designs as well as the cylindrical design shown in FIG. 1.
  • the capillary structures may also be altematively designed; and they may be spaced from, rather than adjacent to, the envelope walls so as to form arterial return paths for the working fluids in the heat pipes.
  • a heat pipe having a capillary structure spaced from an envelope wall is illustrated in US. Pat. No. 3,435,889.
  • the wettable surfaces may be made of ferrous metals other than stainless steel, such as iron and nickel-iron alloys.
  • the envelopes and capillary structures may be made of different materials.
  • Capillary pumping may be effected by porous-fiber and grooved capillary structures.
  • the heat pipes may also employ vapor ducts for separating the working fluid vapors from the returning condensates in the condenser regions thereof. Such vapor ducts are described in US. Pat. application Ser. No. 640,693, filed on May 23, 1967, by W. E. Harbaugh, now Pat. No. 3,568,762.
  • the protective coatings may be made of iron as well as nickel, and may be plated or otherwise deposited onto the wettable surfaces.
  • the cleaning and exhaust procedures may be modified with respect to those described above.
  • the initial firing of the envelope and capillary parts may be performed in a high-vacuum atmosphere at l,000 C. or higher.
  • the refiring of the coated parts may be eliminated where the procedure is found to be unnecessary.
  • a method of making a heat pipe comprising a sealed envelope containing a capillary structure, including at least one surface in said heat pipe being wettable by a mercury metal working fluid, said surface being easily contaminated so as to be poorly wetted by said mercury metal working fluid, comprising the steps of:
  • a method of making a heat pipe comprising a sealed envelope containing a capillary structure, including at least one ferrous metal surface in said heat pipe being wettable by a mercury metal working fluid, comprising the steps of:
  • a method of making a heat pipe comprising a sealed envelope containing an inner wall and a capillary structure each having a ferrous metal surface that is wettable by a mercury metal working fluid, comprising the steps of:

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Chemically Coating (AREA)
  • Heat Treatment Of Articles (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Paints Or Removers (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
US38323A 1970-05-18 1970-05-18 Method of making a heat pipe having an easily contaminated internal wetting surface Expired - Lifetime US3672020A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US3832370A 1970-05-18 1970-05-18

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US3672020A true US3672020A (en) 1972-06-27

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Country Status (8)

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US (1) US3672020A (enrdf_load_stackoverflow)
JP (1) JPS466883A (enrdf_load_stackoverflow)
BE (1) BE767288A (enrdf_load_stackoverflow)
CA (1) CA939988A (enrdf_load_stackoverflow)
CH (1) CH538660A (enrdf_load_stackoverflow)
DE (1) DE2124677C3 (enrdf_load_stackoverflow)
FR (1) FR2090114B1 (enrdf_load_stackoverflow)
GB (1) GB1342923A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921710A (en) * 1972-08-23 1975-11-25 Tokico Ltd Heat pipe and manufacturing method thereof
US4106171A (en) * 1974-11-29 1978-08-15 Hughes Aircraft Company Method for closure of heat pipes and device fabricated thereby
US4240189A (en) * 1976-12-25 1980-12-23 Ricoh Company, Ltd. Method of producing heat pipe roller
US4548258A (en) * 1984-07-02 1985-10-22 Whirlpool Corporation Method and means for inhibiting corrosion in a heat pipe
US20040134643A1 (en) * 2001-01-03 2004-07-15 Rosenfeld John H. Chemically compatible, lightweight heat pipe
US20050026101A1 (en) * 2003-07-28 2005-02-03 Beckett Gas, Inc. Burner manifold apparatus and method for making same
US20060213648A1 (en) * 2005-03-25 2006-09-28 Delta Electronics, Inc. Method for manufacturing heat dissipation apparatus
WO2019006447A1 (en) * 2017-06-30 2019-01-03 Patco, Llc BALCONY INSTALLATION

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013110879A1 (de) * 2013-10-01 2015-04-02 Benteler Automobiltechnik Gmbh Kraftfahrzeug-Wärmeübertragersystem

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1663709A (en) * 1918-01-10 1928-03-27 Delco Light Co Cooling device for valves and the like
US1748518A (en) * 1918-01-10 1930-02-25 Delco Light Co Cooling device for valves and the like

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1663709A (en) * 1918-01-10 1928-03-27 Delco Light Co Cooling device for valves and the like
US1748518A (en) * 1918-01-10 1930-02-25 Delco Light Co Cooling device for valves and the like

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921710A (en) * 1972-08-23 1975-11-25 Tokico Ltd Heat pipe and manufacturing method thereof
US4106171A (en) * 1974-11-29 1978-08-15 Hughes Aircraft Company Method for closure of heat pipes and device fabricated thereby
US4240189A (en) * 1976-12-25 1980-12-23 Ricoh Company, Ltd. Method of producing heat pipe roller
US4548258A (en) * 1984-07-02 1985-10-22 Whirlpool Corporation Method and means for inhibiting corrosion in a heat pipe
US20100263837A1 (en) * 2001-01-03 2010-10-21 Rosenfeld John H Chemically compatible, lightweight heat pipe
US7069978B2 (en) * 2001-01-03 2006-07-04 Thermal Corp. Chemically compatible, lightweight heat pipe
US20040134643A1 (en) * 2001-01-03 2004-07-15 Rosenfeld John H. Chemically compatible, lightweight heat pipe
US8286694B2 (en) 2001-01-03 2012-10-16 Thermal Corp. Chemically compatible, lightweight heat pipe
US20050026101A1 (en) * 2003-07-28 2005-02-03 Beckett Gas, Inc. Burner manifold apparatus and method for making same
US6921262B2 (en) 2003-07-28 2005-07-26 Beckett Gas, Inc. Burner manifold apparatus and method for making same
US20060213648A1 (en) * 2005-03-25 2006-09-28 Delta Electronics, Inc. Method for manufacturing heat dissipation apparatus
WO2019006447A1 (en) * 2017-06-30 2019-01-03 Patco, Llc BALCONY INSTALLATION
CN111356810A (zh) * 2017-06-30 2020-06-30 帕特克有限公司 阳台安装
CN111356810B (zh) * 2017-06-30 2022-03-25 帕特克有限公司 阳台安装
US11585080B2 (en) 2017-06-30 2023-02-21 Patco, Llc Balcony installation

Also Published As

Publication number Publication date
FR2090114A1 (enrdf_load_stackoverflow) 1972-01-14
FR2090114B1 (enrdf_load_stackoverflow) 1974-04-26
DE2124677A1 (de) 1971-12-02
CH538660A (de) 1973-06-30
CA939988A (en) 1974-01-15
DE2124677C3 (de) 1975-01-16
DE2124677B2 (enrdf_load_stackoverflow) 1974-05-22
GB1342923A (en) 1974-01-10
BE767288A (fr) 1971-10-18
JPS466883A (enrdf_load_stackoverflow) 1971-12-15

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