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Publication numberUS3402767 A
Publication typeGrant
Publication dateSep 24, 1968
Filing dateNov 12, 1965
Priority dateNov 23, 1964
Publication numberUS 3402767 A, US 3402767A, US-A-3402767, US3402767 A, US3402767A
InventorsHermann Strub, Josef Bohdansky, Rene Caron
Original AssigneeEuratom
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Heat pipes
US 3402767 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

Sept. 24, 1968 BOHDANSKY ET Al. 3,402,767

. H E A T P I P E S INVENTOR JOS BOHDANSKY RE ARON HERMANN STRUB ilmzwm,m w A ORNEYS United States Patent 3,402,767 HEAT PIPES Josef Bohdansky, Taino, Varese, Ren Caron, Ispra, Varese, and Hermann Strub, Taino, Varese, Italy,

mosphere, for various heat carriers. The values are for optimum heat flow and are calculated for an operating assignors to European Atomic Energy Community 5 temperature at which the vapour phase flows with a veloc- (Euratom), Brussels, Belgium ity below the veloc1ty of sound.

Filed Nov. 12, 1965, Ser. No. 507,450 The symbol "r means the effective capillary radius; in Claims priority, application Germany, Nov. 23, 1964, other terms the width of the capillary passage is 2r. The

28,220 depth of the passage is again twice the width. 3 Claims. (Cl. 165105) Material Cs Rb Na Li Bi Pb Ag Heat flow, kw 3. 3 5. 6 33 95 22 29 63 Max mum temperature, C 450 470 820 1,300 1,600 1,800 2,000 Optimum tube to passage ratio ABSTRACT OF THE DISCLOSURE A closed tubular container of heat resistant material for vaporizing a small quantity of a heat transfer liquid contained in the container. A condensing zone and an evaporation zone are defined in the container and capillary means are disposed therein for transporting condensed liquid from said condensing zone to the evaporation zone. The capillary means are constituted by parallel grooves of capillary diameter formed in the inside wall of the container.

The invention relates to devices known as, and hereinafter referred to as heat pipes.

Heat pipes are disclosed in the Journal of Applied Physics, 35, pages 1990/91, June 1964, and provide a means for transfer of heat. A heat pipe consists essentially of a closed tubular container of heat resistant material, condensable vapour and capillary means disposed within the container. The operation of such a heat pipe depends on the fact that when one of its ends is heated a closed circuit fluid flow arises in the pipe. Vapour flows from the heated end of the pipe to the unheated end and there condenses. The return of the condensate is effected by the capillary means. In heat pipes as at present constructed the capillary means are a separate structure (e.g. a porous ceramic insert or a fine-mesh wire coil) and it has been found that the mechanical insertion of such a separate structure into the container is a source of difficulty as regards satisfactory operation of the heat pipe. The capillary insert may, for example, be deformed with respect to the tube due to the different materials used and the varying thermal stress. As a result the thermal capacity and the heat transfer of the tube is strictly limited. Moreover, drying out of the capillaries and destruction of the tube may occur possibly due to such deformation.

The object of the invention is to provide a heat pipe in which the aforementioned defect is avoided or reduced and therefore works more reliably.

The heat pipe according to the invention is characterized in that the capillary passages are formed directly in the inside wall of the container. The capillaries are, preferably, channels or grooves parallel to the axis or slightly helical.

The optimum width of a capillary passage for use in the invention depends upon a number of factors, more especially the pipe radius R, the operating pressure, and material of the heat carrier or condensable vapour. There fol-' lows a table of values of the ratio R/ r for a tube of 2 cm. diameter and 50 cm. long at an operating pressure of 1 at- The capillary structure according to the invention makes a separate capillary insert unnecessary.

The capillaries follow all movements of the tube and stress defects are obviated.

The capillary passages may be either made in the finished container or formed when the tube to form the container is drawn, for example by using a suitably shaped draw mandrel. The capillaries may also be made by milling, stamping, folding, etching, shock deformation or the like. Attention is finally drawn to the drawings, in which FIG. 1 is a transverse cross-sectional view of a heat pipe according to the present invention, and FIG. 2 is a cross section taken along the line 2--2 of FIG. 1.

As shown, a heat tube 3 is provided which is formed with a pair of end walls 4. A plurality of capillaries 1 are formed in the inside wall 2 of the tube 3 in the axial direction, or are slightly helical. Advantageously, the capillaries are of rectangular cross section, the depth of each capillary being made twice the width.

We claim:

1. A tubular container of heat resistant material containing a small quantity of a heat transfer liquid, said container being closed at each end, and one end of said container being at a higher temperature than the other end thereof to define an evaporation zone and a condensing zone adjacent said ends, said container having a plurality of parallel, substantially longitudinal grooves of capillary diameter formed in the inside wall thereof of a depth substantially more than the width thereof for transporting condensed liquid from said condensing zone to said evaporation zone.

2. A tubular container according to claim 1, wherein said grooves are of a rectangular shape.

3. A tubular container according to claim 1, wherein said grooves extend helically with respect to the axis of said container.

References Cited UNITED STATES PATENTS 2,279,548 4/ 1942 Bailey.

2,840,351 6/1958 Holm --105 X 2,978,797 4/1961 Ekelund 165-479 X 3,217,799 11/1965 Rodgers 13838 X 3,273,599 9/1966 Heeren 165179 X FOREIGN PATENTS D. 15,545 10/1955 Germany.

ROBERT A. OLEARY, Primary Examiner. T. W. STREULE, Assistant Examiner.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2279548 *Jun 11, 1938Apr 14, 1942Babcock & Wilcox CoLiquid vaporizing tube
US2840351 *Sep 10, 1953Jun 24, 1958Air Prcheater CorpTemperature equalizing means for regenerative air preheater structure
US2978797 *Feb 21, 1955Apr 11, 1961Svenska Metallverken AbTubular finned metal sections and manufacture thereof
US3217799 *Mar 26, 1962Nov 16, 1965Calumet & HeclaSteam condenser of the water tube type
US3273599 *Nov 4, 1964Sep 20, 1966 Internally finned condenser tube
*DE15545C Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3457436 *Nov 7, 1966Jul 22, 1969Teledyne IncHeat pipes with unique radiator configuration in combination with thermoionic converters
US3525670 *Dec 17, 1968Aug 25, 1970Atomic Energy CommissionTwo-phase fluid control system
US3528494 *Nov 7, 1966Sep 15, 1970Teledyne IncHeat pipe for low thermal conductivity working fluids
US3613774 *Oct 8, 1969Oct 19, 1971Sanders Associates IncUnilateral heat transfer apparatus
US3665573 *May 18, 1970May 30, 1972Atomic Energy CommissionMethod of fabricating a heat pipe
US3685547 *Apr 28, 1970Aug 22, 1972Combustion EngInternal configuration of pipes and pressure parts
US3803688 *Jul 13, 1971Apr 16, 1974Electronic CommunicationsMethod of making a heat pipe
US3862481 *Sep 26, 1973Jan 28, 1975Philips CorpMethod of manufacturing tubes provided with longitudinal grooves in inner wall and/or outer wall, and tubes manufactured by this method
US3887759 *Mar 20, 1974Jun 3, 1975Gen ElectricEvaporative cooling system employing liquid film evaporation from grooved evaporator surface and vapor push pump for circulating liquid
US4087893 *Nov 5, 1975May 9, 1978Nippon Gakki Seizo Kabushiki KaishaProcess for producing a heat pipe
US4199300 *Mar 6, 1978Apr 22, 1980Rolls-Royce LimitedShroud ring aerofoil capture
US4218179 *May 30, 1978Aug 19, 1980Rolls-Royce LimitedIsothermal aerofoil with insulated internal passageway
US4275510 *Jun 1, 1979Jun 30, 1981George Odean FHeat recovery in a laundry system
US4476704 *Mar 2, 1983Oct 16, 1984Wieland-Werke AgMethod for producing finned tubes
US4733698 *Sep 9, 1986Mar 29, 1988Kabushiki Kaisha Kobe Seiko ShoHeat transfer pipe
US4989319 *Jul 9, 1990Feb 5, 1991Lockheed Missiles & Space Company, Inc.Method of fabricating a graded-groove heat pipe
US7443675 *Jul 19, 2006Oct 28, 2008Mitac Technology Corp.Heat pipe with guided internal grooves and heat dissipation module incorporating the same
DE2552679A1 *Nov 24, 1975Jun 16, 1976Hitachi LtdWaermeuebertragungsrohr
DE2602211A1 *Jan 22, 1976Aug 5, 1976Philips NvWaermeaustauscher
Classifications
U.S. Classification165/104.26, 29/890.32, 165/179, 416/96.00R, 415/114, 416/95, 138/38
International ClassificationF28D15/04
Cooperative ClassificationF28D15/046
European ClassificationF28D15/04B