US3651240A - Heat transfer device - Google Patents
Heat transfer device Download PDFInfo
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- US3651240A US3651240A US797725*A US3651240DA US3651240A US 3651240 A US3651240 A US 3651240A US 3651240D A US3651240D A US 3651240DA US 3651240 A US3651240 A US 3651240A
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- Prior art keywords
- capillary
- heat pipe
- walls
- heating
- chamber
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B3/00—Ohmic-resistance heating
- H05B3/62—Heating elements specially adapted for furnaces
- H05B3/64—Heating elements specially adapted for furnaces using ribbon, rod, or wire heater
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D11/00—Arrangement of elements for electric heating in or on furnaces
- F27D11/02—Ohmic resistance heating
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F27—FURNACES; KILNS; OVENS; RETORTS
- F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
- F27D11/00—Arrangement of elements for electric heating in or on furnaces
- F27D11/06—Induction heating, i.e. in which the material being heated, or its container or elements embodied therein, form the secondary of a transformer
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- 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
- F28D15/0233—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 the conduits having a particular shape, e.g. non-circular cross-section, annular
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- 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
- F28D15/046—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 characterised by the material or the construction of the capillary structure
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F2200/00—Prediction; Simulation; Testing
- F28F2200/005—Testing heat pipes
Definitions
- a heat pipe works on the principle of a reflux boiler and is extremely efficient in terms of transferring large thermal heat fluxes.
- Example of heat pipe devices are described in U.S. Pat. Nos. 3,152,774 and 3,229,759, issued to T. Wyatt and G. M. Grover, respectively.
- the basic heat pipe is a closed tube which has a layer of porous wick material attached to the interior surface of the tube wall.
- the tube or pipe is partially filled with a fluid, the specific fluid being determined by the temperature range desired, which wets the porous wick material and spreads throughout the wick material by capillary forces.
- the recondensed fluid is then transported by capillary forces back to the vaporization region, or high heat flux input zone, to continue the closed loop process of transporting and delivering thermal energy to any and all cool regions of the pipe.
- the heat pipe although heated only in one small region, quickly becomes an isothermal surface; i.e., all surface temperatures on the pipe are equal or nearly equal no matter what the distribution of heat flux input may be.
- a diffusion furnace has a long processing tube 2 to 3 feet in length and several inches in diameter.
- the processing tube is surrounded along its length by a long helical heating coil, which is divided into three coil portions, namely a long central portion and two shorter end portions.
- the three coil portions are separately supplied with electrical heater power so as to produce three separately thermostatically controllable heating zones within the processing tube.
- the three zones are necessary to achieve a flat temperature profile along the longest possible length of the processing tube.
- a flat temperature profile is necessary to assure that all the semiconductor wafers, which are placed in a boat within the processing tube, will be subjected to the same thermal diffusion processing conditions.
- the diffusion process consists of introducing a gaseous impurity or dopant material into the processing tube while the boatload of semiconductor wafers are heated at about l,300 C.
- the present invention resides in a uniquely configured structure utilizing the basic heat pipe concept, and in the recognition that such structures advantageously can be used and ought to be used in certain types of furnaces, such s diffusion furnaces.
- Interior surfaces of an annular pipe are provided with a porous wick material, such as sintered metals, wire screens, or other porous compacts, to provide complete interconnection of fluid flow paths.
- the isothermal annular heat pipe When charged with a working fluid which wets the wick material and has a suitable vapor pressure matching the desired temperature range of interest, the isothermal annular heat pipe" may be used for a variety of heat transfer applications.
- it will produce a flat temperature profile along the entire length of the processing tube or chamber by the use of a single electrical heater coil and a single temperature controller.
- FIG. 1 is a partially broken away diagrammatic view in perspective of a tube furnace employing a structure in accordance with the invention
- FIG. 2 is a side view, partly in section, of the structure
- FIG. 3 is a sectional view taken along line 33 of FIG. 2;
- FIG. 4 is a diagrammatic view showing an alternative form of heater for the structure of FIG. 2;
- FIG. 5 is a graph of curves showing the temperature, as a function of distance along the furnace of two different regions thereof;
- FIG. 6 is a perspective view, with portions removed, of a diffusion furnace employing an annular heat pipe according to the invention.
- FIG. 7 is a cross-sectional view of the furnace assembly of FIG. 6.
- FIGS. 8 and 9 are perspective views of alternativeforms of diffusion furnaces employing annular heat pipes of rectangular cross section.
- FIG. 1 there is shown an oven or furnace 10 provided with a central isothermal working space 12 formed within an annular heat pipe 14.
- An electrical heater coil 16 is wound around one end of the heat pipe 14 and receives electrical power from a voltage source 18.
- the heater coil 16 may be embedded in a thermal insulation sheath 20 that surrounds the heat pipe" 14 along its length.
- the insulation sheath 20 serves to minimize heat loss from the "heat pipe 14 to the surrounding atmosphere.
- the heat pipe 14 includes concentric inner and outer cylindrical metal tubes 22 and 24 respectively.
- the space between the tubes 22 and 24 forms an annular chamber 25.
- the surfaces of the tubes 22 and 24 disposed within the annular chamber 25 are covered with linings 26 and 28 of porous wick material.
- the two wick linings 26 and 28 are spaced apart and joined together by short spacer elements 30 of wick material that are spaced along the length of the tubes 22 and 24.
- the annular chamber 25 is closed at both ends by cover plates 32, such as the one shown in FIG. I, which leave the isothermal working space 12 open for easy access from the outside.
- the annular chamber 25 is evacuated of non-condensable gases, such as air, and contains a vaporizable fluid 34 of sufficient quantity to wet the entire wick material by capillary action. The specific fluid depends upon the operating temperature desired for the heat pipe 14.
- the wick material for the linings 26 and 28 and spacer elements 30 may be in the form of sintered metal, wire screens, or other porous compacts having voids or openings of capillary size and capable of transporting the vaporizable fluid 34.
- the heater coil 16 is energized to heat the portion of the annular heat pipe" 14 surrounded thereby.
- the vapor migrates through the annular chamber 25 where it condenses on all interior surfaces that are below the temperature of the vaporizing surface, thereby giving up the heat of vaporization to and raising the temperature of all the cooler surfaces.
- Continuous vapor flow paths are provided along the annular extent of the annular chamber 25 by means of the linear spacing between the spacer elements 30.
- the condensed fluid 34 is then transported by capillary action through the wick material from these condensing regions to the vaporizing region or high heat flux input zone, where the fluid 34 again vaporizes.
- thermal energy supplied by the heater coil 16 is transported and delivered to any and all cooler interior regions of the chamber 25.
- the result is that the entire surface of the heat pipe" 14 quickly becomes an isothermal surface when operating in the temperature range specified by the working fluid, and the volume within the isothermal working space 12 of the furnace 10 is uniform in temperature along the entire length of the heat pipe 14.
- the lower limit of the equilibrium temperature range is determined by the thermodynamic properties of the working fluid, namely the vapor pressure and the heat of vaporization.
- the upper limit of the equilibrium temperature range is determined by the mechanical ability of the device to withstand the positive pressures of the vapor relative to the surrounding atmosphere.
- the working space 12, being devoid of fluid 34, can be used as an oven to process various articles of manufacture, such as semiconductive devices, without danger of contamination by the working fluid 34.
- the furnace 10 may be used to provide an isothermal environment for various components requiring uniform thermal distribution, with the oven shaped in conformity therewith. Accordingly, whereas the furnace 10 has been shown as having a circular, cylindrical shape, it may have a rectangular cross section oreven a complex cross-sectional shape.
- the tubes 22 and 24 consisted of stainless steel cylinders having lengths of 12 inches, inside diameters of 1.5 inches and 1.9 inches respectively and outside diameters of 1.6 inches and 2.0 inches respectively.
- the wick material was fabricated from four multiple layers of I mesh stainless steel screen.
- the vaporizable fluid was potassium metal.
- FIG. shows curves of temperatures taken along the length of the furnace at two different regions thereof.
- Curve 36 refers to the region indicated in FIG. 1 by dashed line 38 as occupying the space adjacent to the inside surface of the insulation sheath 20.
- Curve 40 refers to the region on the interior surface of the inner tube 22; that is, the surface that bounds the central working space 12. Temperature is plotted along the ordinate and distance along the furnace 10 is plotted along the abscissa. It is seen that the temperature external of the an nular heat pipe 14 increases from 700 C. on one end adjacent to the heater coil 16 to a maximum of over 780 C. just 2 inches away, and then drops to below 600C. at the opposite end. In contrast, the temperature on the interior surface of the inner tube 22 is uniformly at 720 C. along the entire length.
- the present invention provides special advantages when used for processing semiconductor devices. For example, in the art of semiconductor device manufacture, it is necessary to heat wafers of silicon in the presence of dopant materials in a furnace or oven at temperatures of the order of l,000 C. With furnaces in present use, the temperature is fairly uniform in the central portion but drops substantially at the ends. As a result, about 60 percent of the furnace length is unusable. With the present invention, substantially the entire length of the furnace is uniform in temperature, and a much greater length of the furnace zone may be used for treating semiconductor devices. Consequently, in a particular application, the equivalent power consumption for the processing can be significantly reduced.
- Furnaces presently in use utilize several electrical heaters distributed along the furnace length, and each of the heater coils may be individually thermostatically controlled. Maintenance problems arise from the fact that failure can occur from one of the number of heating coils and control circuits. Maintenance problems as well as systems costs are reduced in the present invention in that only a single heater source and control circuit are required.
- the present invention provides additional .special advantages when used for elevated temperature mechanical property testing.
- a furnace is employed to heat the subject specimen.
- Furnaces in presentuse in the art employ a multiplicity of heater coils along the length of the furnace which are individually controlled and adjusted to provide semi-uniform temperature over the active region. When adjusted, such a furnace will provide temperatures uniformity of several degrees variance over the length of interest. During the test sequence, any change in heat balance due to changing test conditions will effect and degrade the thermal uniformity within the furnace volume.
- the present invention eliminates the need for any manual or semiautomatic adjustment of the position of thermal input or temperature uniformity within the volume of the isothermal working space. A single automatic temperature control is thus all that is required to maintain uniformity, throughout the working volume, over any desired temperature within the working range of the heat transfer fluid.
- the invention will now be described as applied to the construction of a diffusion furnace for processing semiconductors.
- a diffusion furnace consisting of a furnace assembly 50 and a power control system 52.
- the furnace assembly 50 includes an outer cabinet or casing 54 lined with thermal insulation 56. Extending longitudinally and centrally of the casing 54 and supported by the insulation 56 is a helical heating coil 58 that is wound around a cylindrical ceramic support tube 60.
- the heating coil 58 serves the same function as the heater coil 16 of FIG. 1, namely that of supplying heating energy to the annular heat pipe 20, which in this difiusion furnace is supported within the support tube 60.
- the heating coil 58 may be formed of high resistance wire that will heat to a high temperature when supplied with electrical current of '60 cycle frequency.
- the heating coil 58 may comprise metal tubing of high electrical conductivity which, when furnished with radio frequency current, will cause the annular heat pipe 20 to heat up by electromagnetic induction.
- a cylindrical processing tube 62 made of suitable material such as quartz is supported within the annular heat pipe 20 and extends longitudinally through both ends thereof.
- the processing tube 62 is provided with an open end 64 through which may be inserted a boat 66 containing wafers 68 of silicon or other semiconductor.
- the other end of the processing tube 62 is provided with a smaller opening 70 through which a suitable gaseous dopant material may be introduced into the processing tube for difiusion into the semiconductor wafers 68.
- the wafer-loaded boat 66 may extend substantially the entire length of the annular heat pipe 20 and even beyond the extremities of the heating coil 58.
- the reason for this is that the effective heating zone for heating the semiconductor wafers 68 is determined by the interior of the annular heat pipe 20 rather than the heating coil 58.
- the effective heating zone has a flat temperature profile along the entire length of the annular heat pipe 20.
- the power control system 52 includes a power supply 72 for furnishing electrical energy to the heating coil 58.
- the power supply 72 is connected to the heating coil 58 through a controller 74.
- a thermocouple 76 contacting the annular heat pipe 20 is connected to the controller 74.
- the thermocouple 76 which may be supported in a tube 77, as shown in FIG. 7, senses changes in heat pipe temperature above and below a given set point for which circuits in the controller 74 are set.
- the circuits in the controller 74 operate to turn on power to the heating coil 58 when the temperature falls below the set point and to turn off power to the heating coil 58 when the temperature rises above the set point.
- controller 74 requires no further detailed description. It will suffice to say that the controller 74 may be one of the kind disclosed in U.S. Pat. No. 3,291,969 issued Dec. 13, 1966, to B. J. Speransky et al., for controlling the central zone B of the heating coil 11 of that patent.
- the power supply 72 may be designed to furnish 60 cycle alternating current to the heating coil 58 if the latter operates on the principle of resistance heating. On the other hand, if the heating coil 58 is an electromagnetic induction heating coil, the power supply 72 may be designed to furnish radio frequency current to the heating coil 58.
- annular heat pipe 20 provides a flat temperature profile along its entire interior length, thereby increasing the capacity of the semiconductor processing zone. Furthermore, whenever it is desired to change the temperature of the furnace, the temperature will rise or fall uniformly along the entire length of the heating zone.
- FIG. 8 there is shown a modified form of diffusion furnace assembly 50a which has a rectangular cross section.
- the processing tube 62a and annular heat pipe 20a are rectangular instead of circular.
- a heater element 58a of flat sinuous form is mounted adjacent to a surface of the heat pipe 20a, such as the top surface thereof.
- the windings of the heater element 58a extend at an angle to the longitudinal axis of the heat pipe 20a and processing tube 620.
- the heater element 580 be of the resistance wire heating type.
- the heater element 58a may be designed for direct thermal contact with the annular heat pipe 20a.
- the heater element 580 may comprise a central current carrying conductor 78 spaced from an outer metal sheath 80 by electrical insulation 82.
- the heater element 58a may be mounted on a flat support member 60a, which itself is mounted on the heat pipe 20a.
- the remaining parts of the furnace assembly 50a are not shown, it being understood that it contains similar parts corresponding to the insulation 56 and casing 54 of FIGS. 6 and 7.
- a control system 52 similar to that already described in connection with FIGS. 6 and 7 may be used with the rectangular furnace assembly 50a.
- FIG. 8 An additional advantage of incorporating an annular heat 'pipe in a diffusion furnace is apparent in FIG. 8. That is, the
- heating element 58a need not envelope the processing tube 62a, as is required in conventional diffusion furnaces. it is sufficient to apply all the required thermal input energy to a localized area of the heat pipe 20a, such as the top surface or a portion thereof, and through the operation of the heat pipe 20a, the entire surface area thereof will attain an isothermal condition. Furthermore, it is not necessary, in the design of the heater element 58a, that great regard be given to precise spacing between turns or windings, or in uniformity in the lengths of the windings.
- FIG. 9 shows another form of rectangular diffusion furnace 50b that is similar to that of FIG. 8.
- the heater element 581 has sinuous windings that extend parallel to the longitudinal axis of the heat pipe 20b and process tube 62b.
- the heater element 58b which may be mounted on a support tube 60b, may cover all four sides of the heat pipe 20b both longitudinally and circumferentially, as shown, or it may cover a less number of sides or only portions thereof.
- a principal advantage of a rectangular configuration for the diffusion furnace assembly is that is minimizes the cross-sectional area of the processing tube required for any boat and semiconductor load configuration. This minimizes the heat loss from the open ends of the furnace and improves the temperature profile thereof.
- a diffusion furnace comprising:
- tubular heat pipe having radially spaced inner and outer walls formed about a central longitudinal opening extending through both ends thereof and end walls closing the ends of said radially spaced walls to form a closed annular chamber;
- said heat pipe including capillary means covering substantially all radially opposing internal surfaces of said walls;
- a processing tube disposed within the opening of said tubular heat pipe substantially coextensively therewith and defining an elongated processing region where semiconductor bodies may be subjected to diffusion process;
- said heat pipe containing a working fluid operative at a temperature range were said semiconductor bodies are subject to diffusion;
- heating means disposed externally of said tubular heat pipe and extending along a major portion of the outer one of said walls for heating the same to the working temperature, whereupon the entire surface thereof surrounding said processing tube becomes isothermal and a flat temperature profile is established within and along the entire length of said elongated processing region that is coextensive with said heat pipe;
- said last mentioned means including additional capillary means extending longitudinally between said end walls and radially between and interconnecting the capillary means on said radially opposing wall surfaces.
- heating means comprises a helical heating coil wound around at least a major portion of the length of said heat pipe.
- a diffusion furnace comprising:
- a processing tube nested within said heat pipe, coextensive therewith, and formed with a horizontally extending opening through which a boat-load of semiconductor bodies may be inserted for disposition along the entire length of said processing tube covered by said heat pipe;
- said heat pipe including radially spaced elongated walls surrounding said processing tube, end walls closing the ends .of said elongated walls and capillary means covering the radially facing surfaces of said elongated walls;
- said heat pipe containing a working fluid operative at a temperature range where said semiconductor bodies are subject to diffusion;
- a heating element supported adjacent to and extending over at least a major outer surface portion of said heat pipe for applying heat thereto;
- said last mentioned means including additional capillary means extending radially between and interconnecting the capillary means on said radially facing wall surfaces and longitudinally between said end walls;
- temperature sensing means thermally coupled to said heat pipe for sensing the temperature thereof
- power controller means coupled between said temperature sensing means and said power supply means for controlling the supply of power to said heating element in response to signals from said temperature sensing means so as to maintain the temperature of said heat pipe substantially constant.
- Furnace apparatus comprising:
- thermal insulation covering the interior of said casing and forming a central, elongated open cavity
- an open-ended tubular heat pipe disposed within said cavisaid heat pipe having radially spaced walls and interconnecting end walls forming a closed annular chamber surrounding a longitudinal passageway, and a capillary structure covering the internal surfaces of said radially spaced walls;
- said heat pipe containing a working fluid of a metal that is vaporizable from the liquid phase within the temperature range in which said heat pipe is intended to operate;
- thermoelectric element disposed adjacent to and extending over at least a major portion of the outer surface of said heat pipe for applying thermal energy thereto;
- said last mentioned means including additional capillary means extending radially between and interconnecting the capillary structures on said radially spaced walls and longitudinally between said end walls;
- temperature control means in circuit with said energy source means for sensing the temperature of the said heat pipe so as to modulate the energy supplied to said heating element by said energy source in such a manner as to maintain the temperature of said heat pipe substantially constant.
- thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, annular chamber surrounding a central opening;
- said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
- capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber
- heating means disposed externally of said chamber and thermally coupled to at least a portion of one of said walls that is covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein;
- said last mentioned means comprising additional capillary means interconnecting the capillary means on said radially spaced walls intermediate said end walls and including a plurality of groups of wick elements spacing said capillary means, said wick elements being circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
- heating means comprises a helical heating coil wound around said device and traversing the same longitudinally.
- heating means comprise sinuous electrical windings extending transversely to the longitudinal extent of said device.
- heating means comprise sinuous electrical windings extending parallel to the longitudinal extent of said device.
- thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central working volume adapted to receive a workpiece;
- said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
- additional capillary means extending radially between and interconnecting the capillary structure on said opposing wall surfaces, said additional capillary means including a plurality of wick elements extending longitudinally and radially and spaced longitudinally within said annular chamber to provide continuous fluid flow paths through said chamber;
- heating means disposed externally of said chamber and thermally coupled to at least a portion thereof that is coextensive with said capillary structure, whereby thermal input energy is uniformly distributed throughout said chamber to establish an isothermal environment for a workpiece to be inserted within said central working volume.
- heating means extends along at least a major portion of the length of said chamber.
- thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated
- annular chamber surrounding a central opening
- said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
- capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber
- heating means disposed externally of said chamber extending ci cumferentially therearound and thermally coupled to at least a major portion of one of said walls covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein;
- said last mentioned means comprising a plurality of groups of wick elements interconnecting and spacing said capillary means intermediate said end walls and circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
- a heat exchanger having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central elongated openmg;
- said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said heat exchanger is intended to operate;
- heating means disposed adjacent and thermally coupled to at least a portion of one of said radially spaced walls for heating the same;
- said last mentioned means comprising a plurality of groups of capillary elements extending intermediate said end walls and cir'cumferentially and longitudinally spaced within said annular chamber.
Abstract
Spaced inner and outer tubes form a closed annular chamber whose inner surfaces contain coverings of wick material that are interconnected through vane-like wicks. The wick material transports a vaporizable working fluid from cold areas where the vapor condenses to warm areas where the fluid vaporizes. An isothermal working space is produced within the central volume bounded by the inner tube and along its entire length, which may be used to advantage for oven or furnace applications or for providing an isothermal jacket.
Description
United States Patent Kirkpatrick 51 Mar. 21, 1972 [54] HEAT TRANSFER DEVICE [72] inventor: Milton E. Kirkpatrick, Palos Verdes Peninsula, Calif.
[73] Assignee: TRW1nc., Redondo Beach, Calif.
[22] Filed: Jan. 31, 1969 [211 Appl. No.: 797,725
Related US. Application Data [63] Continuation-impart of Ser. No. 637,193, May 9,
i967, abandoned.
[52] U.S.Cl ..l3/22,13/1, 13/24, 165/105, 219/399, 219/406, 219/530, 219/540 [51] Int. Cl. ..H05b 3/66, F28d 15/00 [58] Field of Search ..2l9/399, 406, 530, 540, 390, 2l9/413;-165/105;13/22, 1, 24
[5 6] References Cited UNITED STATES PATENTS 1,987,119 1/1935 Long 4219/325 3,311,694 3/1967 Lasch, Jr. ..13/24 2,616,628 11/1952 Guild ....165/105 X 2,820,134 1/1958 Kobayashl ..165/l05 X 3,229,759 1/1966 Grover ..165/105 3,299,196 1/1967 Lasch, Jr. et al.... .....l3/22 X 3,385,921 5/1968 Hampton ..13/24 3,490,718 1/1970 Vary .165/105 X 3,327,772 6/1967 Kodaira 165/105 X OTHER PUBLICATIONS RCA, The Heat Pipe, RCA Electronic Components and Devices Direct Energy Conversion D'ept., Lancaster, Penn., RCA Ref. 994- 619, cover page and 'pp. 6, 7; Feb., 1967 Primary Examiner-Albert W. Davis, .lr. Attorney-Jerry A. Dinardo, Alfred B. Levine and Donald R. Nyhagen ABSTRACT 17 Claims, 9 Drawing Figures PATENTEDMAR21 I972 3.651.240
SHEETl UF 4 Figl Milton E. Kirkpatrick mvsmoa BY MG. 222% AGENT PATENTEDMARZI m2 SHEET 2 [1F 4 Milton E Kirkpatrick INVENTOR.
BY M Q.
AGENT PATENTEUMAREI I972 3.851.240
sum u or 4 Fig.4
lnsldo H009 Pipe sec Outside Hoot Pip.
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Fig.5
D|uonco,lnchos Milton E. Kirkpatrick mvzmon.
AGENT HEAT TRANSFER DEVICE CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to heat transfer devices, and particularly to devices employing capillary fluid transport, which are of such configuration that lends itself especially to oven or furnace applications.
2. Description of the Prior Art The concept and art of building reflux boilers is well developed and dates back to papers on the subject during the 1930's. A heat pipe" works on the principle of a reflux boiler and is extremely efficient in terms of transferring large thermal heat fluxes. Example of heat pipe devices are described in U.S. Pat. Nos. 3,152,774 and 3,229,759, issued to T. Wyatt and G. M. Grover, respectively. The basic heat pipe is a closed tube which has a layer of porous wick material attached to the interior surface of the tube wall. The tube or pipe is partially filled with a fluid, the specific fluid being determined by the temperature range desired, which wets the porous wick material and spreads throughout the wick material by capillary forces.
When a sufficient heat flux is applied to any point on the surface of the pipe, liquid willbe vaporized. Energy equivalent to the heat of vaporization is carried away from the high heat flux region by the vapor that migrates throughout the interior regions of the pipe. The vapor will recondense on any and all interior surfaces which areat temperatures below that of the vaporizing surface, thereby giving up the heat of vaporization to all cooler surfaces.
The recondensed fluid is then transported by capillary forces back to the vaporization region, or high heat flux input zone, to continue the closed loop process of transporting and delivering thermal energy to any and all cool regions of the pipe. As a result of this action, the heat pipe, although heated only in one small region, quickly becomes an isothermal surface; i.e., all surface temperatures on the pipe are equal or nearly equal no matter what the distribution of heat flux input may be.
Inasmuch as the present invention may advantageously be used to provide a diffusion furnace for the semiconductor industry, a brief description of such diffusion furnaces will be given. In the present state of the art, a diffusion furnace has a long processing tube 2 to 3 feet in length and several inches in diameter. The processing tube is surrounded along its length by a long helical heating coil, which is divided into three coil portions, namely a long central portion and two shorter end portions. The three coil portions are separately supplied with electrical heater power so as to produce three separately thermostatically controllable heating zones within the processing tube. The three zones are necessary to achieve a flat temperature profile along the longest possible length of the processing tube. A flat temperature profile is necessary to assure that all the semiconductor wafers, which are placed in a boat within the processing tube, will be subjected to the same thermal diffusion processing conditions. The diffusion process consists of introducing a gaseous impurity or dopant material into the processing tube while the boatload of semiconductor wafers are heated at about l,300 C.
Despite such an elaborate three zone heating arrangement, substantially less than the entire length of the processing tube attains a flat temperature profile. Furthermore, some rather complex electrical control circuitry is required to control or modify the temperatures of the three zones so that the furnace not only attains a flat temperature profile but also maintains it under different boatload conditions.
Reference may be had to the following US. Patents for fuller descriptions of diffusion furnaces and the problems associated therewith:
3,291,969 B. J. Speransky et al. Dec. 13, 1966 3,299,196 C. A. Lasch, Jr., et a]. Jan. 17, 1967 3,311,694 C. A. Lasch, .Ir. March 28, l967 3,370,120 C. A. Lasch, Jr. Feb. 20, 1968 3,385,921 G. P. Hampton May 28, 1968 3,387,078 W. S. Montgomery Jr., et a1. June 4, 1968 3,396,955 R. G. Martinek Aug. 13, 1968 SUMMARY OF THE INVENTION The present invention resides in a uniquely configured structure utilizing the basic heat pipe concept, and in the recognition that such structures advantageously can be used and ought to be used in certain types of furnaces, such s diffusion furnaces. Interior surfaces of an annular pipe are provided with a porous wick material, such as sintered metals, wire screens, or other porous compacts, to provide complete interconnection of fluid flow paths. When charged with a working fluid which wets the wick material and has a suitable vapor pressure matching the desired temperature range of interest, the isothermal annular heat pipe" may be used for a variety of heat transfer applications. In particular, when employed in a diffusion furnace, it will produce a flat temperature profile along the entire length of the processing tube or chamber by the use of a single electrical heater coil and a single temperature controller.
BRIEF DESCRIPTION OF THE DRAWING In the drawing:
FIG. 1 is a partially broken away diagrammatic view in perspective of a tube furnace employing a structure in accordance with the invention;
FIG. 2 is a side view, partly in section, of the structure;
FIG. 3 is a sectional view taken along line 33 of FIG. 2;
FIG. 4 is a diagrammatic view showing an alternative form of heater for the structure of FIG. 2;
FIG. 5 is a graph of curves showing the temperature, as a function of distance along the furnace of two different regions thereof;
FIG. 6 is a perspective view, with portions removed, of a diffusion furnace employing an annular heat pipe according to the invention;
FIG. 7 is a cross-sectional view of the furnace assembly of FIG. 6; and
FIGS. 8 and 9 are perspective views of alternativeforms of diffusion furnaces employing annular heat pipes of rectangular cross section.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, there is shown an oven or furnace 10 provided with a central isothermal working space 12 formed within an annular heat pipe 14. An electrical heater coil 16 is wound around one end of the heat pipe 14 and receives electrical power from a voltage source 18. The heater coil 16 may be embedded in a thermal insulation sheath 20 that surrounds the heat pipe" 14 along its length. The insulation sheath 20 serves to minimize heat loss from the "heat pipe 14 to the surrounding atmosphere.
As shown more clearly in FIGS. 2 and 3, the heat pipe 14 includes concentric inner and outer cylindrical metal tubes 22 and 24 respectively. The space between the tubes 22 and 24 forms an annular chamber 25. The surfaces of the tubes 22 and 24 disposed within the annular chamber 25 are covered with linings 26 and 28 of porous wick material. The two wick linings 26 and 28 are spaced apart and joined together by short spacer elements 30 of wick material that are spaced along the length of the tubes 22 and 24.
The annular chamber 25 is closed at both ends by cover plates 32, such as the one shown in FIG. I, which leave the isothermal working space 12 open for easy access from the outside. The annular chamber 25 is evacuated of non-condensable gases, such as air, and contains a vaporizable fluid 34 of sufficient quantity to wet the entire wick material by capillary action. The specific fluid depends upon the operating temperature desired for the heat pipe 14.
The wick material for the linings 26 and 28 and spacer elements 30 may be in the form of sintered metal, wire screens, or other porous compacts having voids or openings of capillary size and capable of transporting the vaporizable fluid 34.
In the operation of the furnace 10, the heater coil 16 is energized to heat the portion of the annular heat pipe" 14 surrounded thereby. The fluid 34 heated thereby vaporizes and the vapor carries away from the high heat flux region thermal energy equivalent to the heat of vaporization. The vapor migrates through the annular chamber 25 where it condenses on all interior surfaces that are below the temperature of the vaporizing surface, thereby giving up the heat of vaporization to and raising the temperature of all the cooler surfaces. Continuous vapor flow paths are provided along the annular extent of the annular chamber 25 by means of the linear spacing between the spacer elements 30. The condensed fluid 34 is then transported by capillary action through the wick material from these condensing regions to the vaporizing region or high heat flux input zone, where the fluid 34 again vaporizes.
By means of this closed loop process, thermal energy supplied by the heater coil 16 is transported and delivered to any and all cooler interior regions of the chamber 25. The result is that the entire surface of the heat pipe" 14 quickly becomes an isothermal surface when operating in the temperature range specified by the working fluid, and the volume within the isothermal working space 12 of the furnace 10 is uniform in temperature along the entire length of the heat pipe 14.
For a specific working fluid, there is a range of equilibrium temperatures over which the device of this invention will provide isothermal conditions. The lower limit of the equilibrium temperature range is determined by the thermodynamic properties of the working fluid, namely the vapor pressure and the heat of vaporization. The upper limit of the equilibrium temperature range is determined by the mechanical ability of the device to withstand the positive pressures of the vapor relative to the surrounding atmosphere.
The working space 12, being devoid of fluid 34, can be used as an oven to process various articles of manufacture, such as semiconductive devices, without danger of contamination by the working fluid 34. In addition, the furnace 10 may be used to provide an isothermal environment for various components requiring uniform thermal distribution, with the oven shaped in conformity therewith. Accordingly, whereas the furnace 10 has been shown as having a circular, cylindrical shape, it may have a rectangular cross section oreven a complex cross-sectional shape.
In accordance with an exemplary operative embodiment, the tubes 22 and 24 consisted of stainless steel cylinders having lengths of 12 inches, inside diameters of 1.5 inches and 1.9 inches respectively and outside diameters of 1.6 inches and 2.0 inches respectively. The wick material was fabricated from four multiple layers of I mesh stainless steel screen. The vaporizable fluid was potassium metal.
For applications where temperatures in excess of l,000 C. are required, such as in the treatment of semiconductor devices, working fluids such as lithium or other liquid metals having the desired vaporization temperature can be employed. For applications requiring high operating temperatures it will prove advantageous to utilize silicon carbide rods as heating elements, rather than heater coils. In FIG. 4, for example, two or more such rods 35 may be arranged side by side beneath the annular heat pipe" 14 as shown. The rods 35 may be connected in parallel with the voltage source 18.
FIG. shows curves of temperatures taken along the length of the furnace at two different regions thereof. Curve 36 refers to the region indicated in FIG. 1 by dashed line 38 as occupying the space adjacent to the inside surface of the insulation sheath 20. Curve 40 refers to the region on the interior surface of the inner tube 22; that is, the surface that bounds the central working space 12. Temperature is plotted along the ordinate and distance along the furnace 10 is plotted along the abscissa. It is seen that the temperature external of the an nular heat pipe 14 increases from 700 C. on one end adjacent to the heater coil 16 to a maximum of over 780 C. just 2 inches away, and then drops to below 600C. at the opposite end. In contrast, the temperature on the interior surface of the inner tube 22 is uniformly at 720 C. along the entire length.
The present invention provides special advantages when used for processing semiconductor devices. For example, in the art of semiconductor device manufacture, it is necessary to heat wafers of silicon in the presence of dopant materials in a furnace or oven at temperatures of the order of l,000 C. With furnaces in present use, the temperature is fairly uniform in the central portion but drops substantially at the ends. As a result, about 60 percent of the furnace length is unusable. With the present invention, substantially the entire length of the furnace is uniform in temperature, and a much greater length of the furnace zone may be used for treating semiconductor devices. Consequently, in a particular application, the equivalent power consumption for the processing can be significantly reduced.
Furnaces presently in use utilize several electrical heaters distributed along the furnace length, and each of the heater coils may be individually thermostatically controlled. Maintenance problems arise from the fact that failure can occur from one of the number of heating coils and control circuits. Maintenance problems as well as systems costs are reduced in the present invention in that only a single heater source and control circuit are required.
The present invention provides additional .special advantages when used for elevated temperature mechanical property testing. In the art of property testing, a furnace is employed to heat the subject specimen. Furnaces in presentuse in the art, employ a multiplicity of heater coils along the length of the furnace which are individually controlled and adjusted to provide semi-uniform temperature over the active region. When adjusted, such a furnace will provide temperatures uniformity of several degrees variance over the length of interest. During the test sequence, any change in heat balance due to changing test conditions will effect and degrade the thermal uniformity within the furnace volume. The present invention eliminates the need for any manual or semiautomatic adjustment of the position of thermal input or temperature uniformity within the volume of the isothermal working space. A single automatic temperature control is thus all that is required to maintain uniformity, throughout the working volume, over any desired temperature within the working range of the heat transfer fluid.
The invention will now be described as applied to the construction of a diffusion furnace for processing semiconductors. Referring to FIGS. 6 and 7, there is shown a diffusion furnace consisting of a furnace assembly 50 and a power control system 52. The furnace assembly 50 includes an outer cabinet or casing 54 lined with thermal insulation 56. Extending longitudinally and centrally of the casing 54 and supported by the insulation 56 is a helical heating coil 58 that is wound around a cylindrical ceramic support tube 60.
, The heating coil 58 serves the same function as the heater coil 16 of FIG. 1, namely that of supplying heating energy to the annular heat pipe 20, which in this difiusion furnace is supported within the support tube 60. Tothis end, the heating coil 58 may be formed of high resistance wire that will heat to a high temperature when supplied with electrical current of '60 cycle frequency. Alternatively, the heating coil 58 may comprise metal tubing of high electrical conductivity which, when furnished with radio frequency current, will cause the annular heat pipe 20 to heat up by electromagnetic induction.
, A cylindrical processing tube 62 made of suitable material such as quartz is supported within the annular heat pipe 20 and extends longitudinally through both ends thereof. The processing tube 62 is provided with an open end 64 through which may be inserted a boat 66 containing wafers 68 of silicon or other semiconductor. The other end of the processing tube 62 is provided with a smaller opening 70 through which a suitable gaseous dopant material may be introduced into the processing tube for difiusion into the semiconductor wafers 68. Y
It will be observed that the wafer-loaded boat 66, or a plurality thereof arranged end to end, may extend substantially the entire length of the annular heat pipe 20 and even beyond the extremities of the heating coil 58. The reason for this is that the effective heating zone for heating the semiconductor wafers 68 is determined by the interior of the annular heat pipe 20 rather than the heating coil 58. The effective heating zone has a flat temperature profile along the entire length of the annular heat pipe 20.
The power control system 52 includes a power supply 72 for furnishing electrical energy to the heating coil 58. The power supply 72 is connected to the heating coil 58 through a controller 74. A thermocouple 76 contacting the annular heat pipe 20 is connected to the controller 74. The thermocouple 76, which may be supported in a tube 77, as shown in FIG. 7, senses changes in heat pipe temperature above and below a given set point for which circuits in the controller 74 are set. The circuits in the controller 74 operate to turn on power to the heating coil 58 when the temperature falls below the set point and to turn off power to the heating coil 58 when the temperature rises above the set point.
Temperature control systems for difiusion furnaces are well known in the art and therefore the controller 74 requires no further detailed description. It will suffice to say that the controller 74 may be one of the kind disclosed in U.S. Pat. No. 3,291,969 issued Dec. 13, 1966, to B. J. Speransky et al., for controlling the central zone B of the heating coil 11 of that patent.
The power supply 72 may be designed to furnish 60 cycle alternating current to the heating coil 58 if the latter operates on the principle of resistance heating. On the other hand, if the heating coil 58 is an electromagnetic induction heating coil, the power supply 72 may be designed to furnish radio frequency current to the heating coil 58.
It will be seen that the diffusion furnace thus described is much simpler in the construction of its furnace assembly 50 and its control system 52 than the corresponding structure of conventional diffusion furnaces. The inclusion of an annular heat pipe according to the invention permits the use of a single heater coil instead of three and a single temperature control system instead of three. The annular heat pipe 20 provides a flat temperature profile along its entire interior length, thereby increasing the capacity of the semiconductor processing zone. Furthermore, whenever it is desired to change the temperature of the furnace, the temperature will rise or fall uniformly along the entire length of the heating zone.
Referring now to FIG. 8, there is shown a modified form of diffusion furnace assembly 50a which has a rectangular cross section. Thus, the processing tube 62a and annular heat pipe 20a are rectangular instead of circular. A heater element 58a of flat sinuous form is mounted adjacent to a surface of the heat pipe 20a, such as the top surface thereof. The windings of the heater element 58a extend at an angle to the longitudinal axis of the heat pipe 20a and processing tube 620. With this flat configuration, it is preferably that the heater element 580 be of the resistance wire heating type. The heater element 58a may be designed for direct thermal contact with the annular heat pipe 20a. For example, the heater element 580 may comprise a central current carrying conductor 78 spaced from an outer metal sheath 80 by electrical insulation 82. Alternatively, for convenience in assembly or disassembly, the heater element 58a may be mounted on a flat support member 60a, which itself is mounted on the heat pipe 20a. For ease in illustration, the remaining parts of the furnace assembly 50a are not shown, it being understood that it contains similar parts corresponding to the insulation 56 and casing 54 of FIGS. 6 and 7. Likewise, a control system 52 similar to that already described in connection with FIGS. 6 and 7 may be used with the rectangular furnace assembly 50a.
An additional advantage of incorporating an annular heat 'pipe in a diffusion furnace is apparent in FIG. 8. That is, the
heating element 58a need not envelope the processing tube 62a, as is required in conventional diffusion furnaces. it is sufficient to apply all the required thermal input energy to a localized area of the heat pipe 20a, such as the top surface or a portion thereof, and through the operation of the heat pipe 20a, the entire surface area thereof will attain an isothermal condition. Furthermore, it is not necessary, in the design of the heater element 58a, that great regard be given to precise spacing between turns or windings, or in uniformity in the lengths of the windings.
FIG. 9 shows another form of rectangular diffusion furnace 50b that is similar to that of FIG. 8. In this embodiment, the heater element 581: has sinuous windings that extend parallel to the longitudinal axis of the heat pipe 20b and process tube 62b. The heater element 58b, which may be mounted on a support tube 60b, may cover all four sides of the heat pipe 20b both longitudinally and circumferentially, as shown, or it may cover a less number of sides or only portions thereof.
A principal advantage of a rectangular configuration for the diffusion furnace assembly is that is minimizes the cross-sectional area of the processing tube required for any boat and semiconductor load configuration. This minimizes the heat loss from the open ends of the furnace and improves the temperature profile thereof.
The embodiments of the invention in which an exclusive property or privilege is claimed and defined as follows:
1. A diffusion furnace, comprising:
a tubular heat pipe having radially spaced inner and outer walls formed about a central longitudinal opening extending through both ends thereof and end walls closing the ends of said radially spaced walls to form a closed annular chamber;
said heat pipe including capillary means covering substantially all radially opposing internal surfaces of said walls;
a processing tube disposed within the opening of said tubular heat pipe substantially coextensively therewith and defining an elongated processing region where semiconductor bodies may be subjected to diffusion process;
said heat pipe containing a working fluid operative at a temperature range were said semiconductor bodies are subject to diffusion;
heating means disposed externally of said tubular heat pipe and extending along a major portion of the outer one of said walls for heating the same to the working temperature, whereupon the entire surface thereof surrounding said processing tube becomes isothermal and a flat temperature profile is established within and along the entire length of said elongated processing region that is coextensive with said heat pipe; and
means for transporting said working fluid in its liquid phase from the capillary means on said inner wall to the capillary means on said outer wall, said last mentioned means including additional capillary means extending longitudinally between said end walls and radially between and interconnecting the capillary means on said radially opposing wall surfaces.
2. The invention according to claim 1, wherein said heating means comprises a helical heating coil wound around at least a major portion of the length of said heat pipe.
3. A diffusion furnace, comprising:
an elongated outer casing;
a lining of thermal insulation within said outer casing and formed with a central horizontally extending longitudinal cavity;
an open-ended tubular heat pipe nested within said cavity;
a processing tube nested within said heat pipe, coextensive therewith, and formed with a horizontally extending opening through which a boat-load of semiconductor bodies may be inserted for disposition along the entire length of said processing tube covered by said heat pipe;
said heat pipe including radially spaced elongated walls surrounding said processing tube, end walls closing the ends .of said elongated walls and capillary means covering the radially facing surfaces of said elongated walls;
' said heat pipe containing a working fluid operative at a temperature range where said semiconductor bodies are subject to diffusion;
a heating element supported adjacent to and extending over at least a major outer surface portion of said heat pipe for applying heat thereto;
means for transporting said working fluid in its liquid phase from the capillary means on the inner one of said radially spaced walls to the capillary means on the outer one of said radially spaced walls;
said last mentioned means including additional capillary means extending radially between and interconnecting the capillary means on said radially facing wall surfaces and longitudinally between said end walls;
temperature sensing means thermally coupled to said heat pipe for sensing the temperature thereof;
power supply means connected with said heating element for furnishing heating power thereto; and
power controller means coupled between said temperature sensing means and said power supply means for controlling the supply of power to said heating element in response to signals from said temperature sensing means so as to maintain the temperature of said heat pipe substantially constant.
4. Furnace apparatus, comprising:
an outer casing;
thermal insulation covering the interior of said casing and forming a central, elongated open cavity;
an open-ended tubular heat pipe disposed within said cavisaid heat pipe having radially spaced walls and interconnecting end walls forming a closed annular chamber surrounding a longitudinal passageway, and a capillary structure covering the internal surfaces of said radially spaced walls;
said heat pipe containing a working fluid of a metal that is vaporizable from the liquid phase within the temperature range in which said heat pipe is intended to operate;
a heating element disposed adjacent to and extending over at least a major portion of the outer surface of said heat pipe for applying thermal energy thereto;
means for transporting said working fluid in its liquid phase from the capillary structure of the inner one of said radially spaced walls to the capillary structure on the outer one of said radially spaced walls, said last mentioned means including additional capillary means extending radially between and interconnecting the capillary structures on said radially spaced walls and longitudinally between said end walls;
energy source means for applying heating energy to said heating element; and
temperature control means in circuit with said energy source means for sensing the temperature of the said heat pipe so as to modulate the energy supplied to said heating element by said energy source in such a manner as to maintain the temperature of said heat pipe substantially constant.
5. In combination:
a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, annular chamber surrounding a central opening;
said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber;
' heating means disposed externally of said chamber and thermally coupled to at least a portion of one of said walls that is covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein; and
means for transporting said metallic substance in its liquid phase from the capillary means on the other one of said radially spaced walls to the capillary means on said one wall, said last mentioned means comprising additional capillary means interconnecting the capillary means on said radially spaced walls intermediate said end walls and including a plurality of groups of wick elements spacing said capillary means, said wick elements being circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
6. The invention according to claim 5, wherein said capillary means are arranged to provide capillary fluid transport and return of said substance in its liquid phase.
7. Tile invention according to claim 5, wherein said heating means extends along at least a major portion of the length of said chamber.
8. The invention according to claim 5, wherein said heating means is uniformly distributed along the length of said chamber. 1
9. The invention according to claim 5, and further including means mounting said thermal transfer device with its annular chamber extending horizontally.
10. The invention according to claim 5, and further including an insulation sheath surrounding said device and heating means.
11. The invention according to claim 5, wherein said heating means comprises a helical heating coil wound around said device and traversing the same longitudinally.
12. The invention according to claim 5, wherein said heating means comprise sinuous electrical windings extending transversely to the longitudinal extent of said device.
13. The invention according to claim 5, wherein said heating means comprise sinuous electrical windings extending parallel to the longitudinal extent of said device.
14. In combination:
a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central working volume adapted to receive a workpiece;
said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
means forming a capillary structure covering substantially all radially opposing internal wall surfaces of said annular chamber;
additional capillary means extending radially between and interconnecting the capillary structure on said opposing wall surfaces, said additional capillary means including a plurality of wick elements extending longitudinally and radially and spaced longitudinally within said annular chamber to provide continuous fluid flow paths through said chamber;
and heating means disposed externally of said chamber and thermally coupled to at least a portion thereof that is coextensive with said capillary structure, whereby thermal input energy is uniformly distributed throughout said chamber to establish an isothermal environment for a workpiece to be inserted within said central working volume.
15. The invention according to claim 14, wherein said heating means extends along at least a major portion of the length of said chamber.
16. In combination:
a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated,
annular chamber surrounding a central opening;
said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate;
capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber; 7
heating means disposed externally of said chamber extending ci cumferentially therearound and thermally coupled to at least a major portion of one of said walls covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein; and
means for transporting said metallic substance in its liquid phase from the capillary means on the other one of said radially spaced walls to the capillary means on said one wall, said last mentioned means comprising a plurality of groups of wick elements interconnecting and spacing said capillary means intermediate said end walls and circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
17. in combination:
a heat exchanger having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central elongated openmg;
said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said heat exchanger is intended to operate;
heating means disposed adjacent and thermally coupled to at least a portion of one of said radially spaced walls for heating the same;
meansforming a capillary structure for said substance and covering the internal surface of at least the portion of said wall that is adjacent said heating means; and
means for transporting said substance in its liquid phase from the other one of said radially spaced walls to said capillary structure, said last mentioned means comprising a plurality of groups of capillary elements extending intermediate said end walls and cir'cumferentially and longitudinally spaced within said annular chamber.
# l i III I! Patent 3,651,240 Dated March 21 1972 Invento'r(s) Milton E. Kirkpatrick It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
(SEAL) Attest:
EDWARD M.FLE'I'CHER,JR. ROBERT GOTTSCHALK Attesting' Officer I Commissioner of Patents FORM po'mso v USCOMM-DC 60376-P69 Urs- GOVIINNINY PRINTING OFFICI: ".9 O-Qll-lll UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,651,240 Dated March 21 1972 Inventor(s) Milton E. Kirkpatrick It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:
(SEAL) Attest:
EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting' Officer Commissioner of Patents FORM Po-wso (IO-69) cwwnc mans-P1 i U GOVIINNINT PRINTING OFFICE: "I! 0-S6l-J
Claims (17)
1. A diffusion furnace, comprising: a tubular heat pipe having radially spaced inner and outer walls formed about a central longitudinal opening extending through both ends thereof and end walls closing the ends of said radially spaced walls to form a closed annular chamber; said heat pipe including capillary means covering substantially all radially opposing internal surfaces of said walls; a processing tube disposed within the opening of said tubular heat pipe substantially coextensively therewith and defining an elongated processing region where semiconductor bodies may be subjected to diffusion process; said heat pipe containing a working fluid operative at a temperature range were said semiconductor bodies are subject to diffusion; heating means disposed externally of said tubular heat pipe and extending along a major portion of the outer one of said walls for heating the same to the working temperature, whereupon the entire surface thereof surrounding said processing tube becomes isothermal and a flat temperature profile is established within and along the entire length of said elongated processing region that is coextensive with said heat pipe; and means for transporting said working fluid in its liquid phase from the capillary means on said inner wall to the capillary means on said outer wall, said last mentioned means including additional capillary means extending longitudinally between said end walls and radially between and interconnecting the capillary means on said radially opposing wall surfaces.
2. The invention according to claim 1, wherein said heating means comprises a helical heating coil wound around at least a major portion of the length of said heat pipe.
3. A diffusion furnace, comprising: an elongated outer casing; a lining of thermal insulation within said outer casing and formed with a central horizontally extending longitudinal cavity; an open-ended tubular heat pipe nested within said cavity; a processing tube nested within said heat pipe, coextensive therewith, and formed with a horizontally extending opening through which a boat-load of semiconductor bodies may be inserted for disposition along the entire length of said processing tube covered by said heat pipe; said heat pipe including radially spaced elongated walls surrounding said processing tube, end walls closing the ends of said elongated walls and capillary means covering the radially facing surfaces of said elongated walls; said heat pipe containing a working fluid operative at a temperature range where said semiconductor bodies are subject to diffusion; a heating element supported adjacent to and extending over at least a major outer surface portion of said heat pipe for applying heat thereto; means for transporting said working fluid in its liquid phase from the capillary means on the inner one of said radially spaced walls to the capillary means on the outer one of said radially spaced walls; said last mentioned means including additional capillary means extending radially between and interconnecting the capillary means on said radially facing wall surfaces and longitudinally between said end walls; temperature sensing means thermally coupled to said heat pipe for sensing the temperature thereof; power supply means connected with said heating element for furnishing heating power thereto; and power controller means coupled between said temperature sensing means and said power supply means for controlling the supply of power to said heating element in response to signals froM said temperature sensing means so as to maintain the temperature of said heat pipe substantially constant.
4. Furnace apparatus, comprising: an outer casing; thermal insulation covering the interior of said casing and forming a central, elongated open cavity; an open-ended tubular heat pipe disposed within said cavity; said heat pipe having radially spaced walls and interconnecting end walls forming a closed annular chamber surrounding a longitudinal passageway, and a capillary structure covering the internal surfaces of said radially spaced walls; said heat pipe containing a working fluid of a metal that is vaporizable from the liquid phase within the temperature range in which said heat pipe is intended to operate; a heating element disposed adjacent to and extending over at least a major portion of the outer surface of said heat pipe for applying thermal energy thereto; means for transporting said working fluid in its liquid phase from the capillary structure of the inner one of said radially spaced walls to the capillary structure on the outer one of said radially spaced walls, said last mentioned means including additional capillary means extending radially between and interconnecting the capillary structures on said radially spaced walls and longitudinally between said end walls; energy source means for applying heating energy to said heating element; and temperature control means in circuit with said energy source means for sensing the temperature of the said heat pipe so as to modulate the energy supplied to said heating element by said energy source in such a manner as to maintain the temperature of said heat pipe substantially constant.
5. In combination: a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, annular chamber surrounding a central opening; said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate; capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber; heating means disposed externally of said chamber and thermally coupled to at least a portion of one of said walls that is covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein; and means for transporting said metallic substance in its liquid phase from the capillary means on the other one of said radially spaced walls to the capillary means on said one wall, said last mentioned means comprising additional capillary means interconnecting the capillary means on said radially spaced walls intermediate said end walls and including a plurality of groups of wick elements spacing said capillary means, said wick elements being circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
6. The invention according to claim 5, wherein said capillary means are arranged to provide capillary fluid transport and return of said substance in its liquid phase.
7. THe invention according to claim 5, wherein said heating means extends along at least a major portion of the length of said chamber.
8. The invention according to claim 5, wherein said heating means is uniformly distributed along the length of said chamber.
9. The invention according to claim 5, and further including means mounting said thermal transfer device with its annular chamber extending horizontally.
10. The invention according to claim 5, and further including an insulation sheath surrounding said device and heating means.
11. The invention according to claim 5, wherein said heating means comprises a helical heating coil wound arouNd said device and traversing the same longitudinally.
12. The invention according to claim 5, wherein said heating means comprise sinuous electrical windings extending transversely to the longitudinal extent of said device.
13. The invention according to claim 5, wherein said heating means comprise sinuous electrical windings extending parallel to the longitudinal extent of said device.
14. In combination: a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central working volume adapted to receive a workpiece; said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate; means forming a capillary structure covering substantially all radially opposing internal wall surfaces of said annular chamber; additional capillary means extending radially between and interconnecting the capillary structure on said opposing wall surfaces, said additional capillary means including a plurality of wick elements extending longitudinally and radially and spaced longitudinally within said annular chamber to provide continuous fluid flow paths through said chamber; and heating means disposed externally of said chamber and thermally coupled to at least a portion thereof that is coextensive with said capillary structure, whereby thermal input energy is uniformly distributed throughout said chamber to establish an isothermal environment for a workpiece to be inserted within said central working volume.
15. The invention according to claim 14, wherein said heating means extends along at least a major portion of the length of said chamber.
16. In combination: a thermal transfer device having radially spaced walls and interconnecting end walls forming a closed, evacuated, annular chamber surrounding a central opening; said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said thermal transfer device is intended to operate; capillary means covering substantially all internal surfaces of said radially spaced walls within said chamber; heating means disposed externally of said chamber extending circumferentially therearound and thermally coupled to at least a major portion of one of said walls covered by said capillary means, whereby thermal input energy received from said heating means is uniformly distributed throughout said chamber to establish substantially isothermal conditions therein; and means for transporting said metallic substance in its liquid phase from the capillary means on the other one of said radially spaced walls to the capillary means on said one wall, said last mentioned means comprising a plurality of groups of wick elements interconnecting and spacing said capillary means intermediate said end walls and circumferentially and longitudinally spaced within said annular chamber to provide continuous fluid flow paths through said chamber.
17. In combination: a heat exchanger having radially spaced walls and interconnecting end walls forming a closed, evacuated, elongated annular chamber surrounding a central elongated opening; said annular chamber being evacuated of all non-condensable gases and being partially filled with a metallic substance that is vaporizable from the liquid phase within the temperature range in which said heat exchanger is intended to operate; heating means disposed adjacent and thermally coupled to at least a portion of one of said radially spaced walls for heating the same; means forming a capillary structure for said substance and covering the internal surface of at least the portion of said wall that is adjacent said heating means; and means for transporting said substance in its liquid phase from the other one of said radially spaced walls to said capillary structure, said last mentioned means comprising a plurality of groups of capillary elements extending intermediate said end walls and circumferentially and longitudinally spaced within said annular chamber.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US79772569A | 1969-01-31 | 1969-01-31 | |
FR7003307A FR2074806A1 (en) | 1969-01-31 | 1970-01-30 | HEAT TRANSFER DEVICE |
Publications (1)
Publication Number | Publication Date |
---|---|
US3651240A true US3651240A (en) | 1972-03-21 |
Family
ID=26215522
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US797725*A Expired - Lifetime US3651240A (en) | 1969-01-31 | 1969-01-31 | Heat transfer device |
Country Status (5)
Country | Link |
---|---|
US (1) | US3651240A (en) |
CA (1) | CA971951A (en) |
FR (1) | FR2074806A1 (en) |
GB (1) | GB1304771A (en) |
NL (1) | NL154828B (en) |
Cited By (39)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3770047A (en) * | 1972-01-10 | 1973-11-06 | Trw | Apparatus for unidirectionally solidifying metals |
US3812908A (en) * | 1972-02-25 | 1974-05-28 | Philips Corp | Heat transferring device |
US3857990A (en) * | 1972-04-06 | 1974-12-31 | Massachusetts Inst Technology | Heat pipe furnace |
US3943964A (en) * | 1970-07-07 | 1976-03-16 | U.S. Philips Corporation | Heating device |
US3955618A (en) * | 1972-07-19 | 1976-05-11 | U.S. Philips Corporation | Heating device |
US3965334A (en) * | 1972-05-04 | 1976-06-22 | N.V. Philips Corporation | Heating device |
US4091264A (en) * | 1976-08-13 | 1978-05-23 | Seal Incorporated | Heat transfer |
US4095647A (en) * | 1972-07-09 | 1978-06-20 | U.S. Philips Corporation | Heating device |
US4585923A (en) * | 1982-09-23 | 1986-04-29 | Binder Peter M | Heating cabinet |
US4889276A (en) * | 1988-11-07 | 1989-12-26 | Rohr Industries, Inc. | Method and apparatus for forming and bonding metal assemblies |
US5072094A (en) * | 1990-09-11 | 1991-12-10 | United States Department Of Energy | Tube furnace |
US5164626A (en) * | 1990-06-14 | 1992-11-17 | Fujikura Ltd. | Coil element and heat generating motor assembled therefrom |
US20050019234A1 (en) * | 2003-07-21 | 2005-01-27 | Chin-Kuang Luo | Vapor-liquid separating type heat pipe device |
US20050024831A1 (en) * | 2003-07-28 | 2005-02-03 | Phillips Alfred L. | Flexible loop thermosyphon |
US20060201656A1 (en) * | 2002-03-29 | 2006-09-14 | Hon Hai Precision Ind Co., Ltd. | Heat pipe incorporating outer and inner pipes |
US20070107453A1 (en) * | 2005-11-16 | 2007-05-17 | Honeywell International Inc. | Heat exchanger with embedded heater |
US20080121497A1 (en) * | 2006-11-27 | 2008-05-29 | Christopher Esterson | Heated/cool screw conveyor |
US20110315082A1 (en) * | 2010-06-29 | 2011-12-29 | Hon Hai Precision Industry Co., Ltd. | Film coating apparatus |
US20120153298A1 (en) * | 2007-02-16 | 2012-06-21 | Caracal, Inc. | Epitaxial growth system for fast heating and cooling |
US20150075753A1 (en) * | 2012-04-25 | 2015-03-19 | Toshiba Mitsubishi-Electric Industrial Systems Corporation | Heat transfer device |
US20160120221A1 (en) * | 2014-05-21 | 2016-05-05 | Philip Morris Products S.A. | Aerosol-generating system comprising a mesh susceptor |
US20160255681A1 (en) * | 2015-02-26 | 2016-09-01 | Inductive Engineering Technology, LLC | Magnetic induction heat engine and heat pipe delivery system and methods of producing and delivering heat |
CN106246589A (en) * | 2016-08-08 | 2016-12-21 | 洛阳轴研科技股份有限公司 | A kind of bearing Special heat dissipating cover for seat |
US20170020193A1 (en) * | 2015-07-24 | 2017-01-26 | R.J. Reynolds Tobacco Company | Aerosol delivery device with radiant heating |
WO2018027208A1 (en) * | 2016-08-05 | 2018-02-08 | Sandvik Thermal Process Inc. | Thermal process device with non-uniform insulation |
US10028535B2 (en) | 2014-05-21 | 2018-07-24 | Philip Morris Products S.A. | Aerosol-generating system comprising a planar induction coil |
CN108709444A (en) * | 2018-06-19 | 2018-10-26 | 哈尔滨工程大学 | A kind of Horizontal heat pipe for accelerating condensate liquid reflux and enhanced heat exchange |
CN108870974A (en) * | 2018-07-26 | 2018-11-23 | 青岛晨立电子有限公司 | Spread furnace body |
US10219548B2 (en) | 2006-10-18 | 2019-03-05 | Rai Strategic Holdings, Inc. | Tobacco-containing smoking article |
US10300225B2 (en) | 2010-05-15 | 2019-05-28 | Rai Strategic Holdings, Inc. | Atomizer for a personal vaporizing unit |
US10349684B2 (en) | 2015-09-15 | 2019-07-16 | Rai Strategic Holdings, Inc. | Reservoir for aerosol delivery devices |
US10375994B2 (en) | 2014-05-21 | 2019-08-13 | Philip Morris Products S.A. | Aerosol-generating system comprising a fluid permeable susceptor element |
US10492542B1 (en) | 2011-08-09 | 2019-12-03 | Rai Strategic Holdings, Inc. | Smoking articles and use thereof for yielding inhalation materials |
US20200378690A1 (en) * | 2019-05-27 | 2020-12-03 | Asia Vital Components (China) Co., Ltd. | Heat dissipation unit with axial capillary structure |
US11134544B2 (en) | 2015-07-24 | 2021-09-28 | Rai Strategic Holdings, Inc. | Aerosol delivery device with radiant heating |
US11344683B2 (en) | 2010-05-15 | 2022-05-31 | Rai Strategic Holdings, Inc. | Vaporizer related systems, methods, and apparatus |
US11493280B2 (en) * | 2016-03-01 | 2022-11-08 | Cooler Master Co., Ltd. | Heat pipe module and heat dissipating device using the same |
US11659868B2 (en) | 2014-02-28 | 2023-05-30 | Rai Strategic Holdings, Inc. | Control body for an electronic smoking article |
US11812536B2 (en) | 2019-06-10 | 2023-11-07 | Inductive Engineering Technology, LLC | Magnetic induction fluid heater |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL8000469A (en) * | 1980-01-25 | 1981-01-30 | Akzo Nv | SOLAR COLLECTOR WITH A HEAT EXCHANGER. |
GB8422852D0 (en) * | 1984-09-11 | 1984-11-07 | Atomic Energy Authority Uk | Heat pipe stabilised specimen container |
CN113664218A (en) * | 2021-08-31 | 2021-11-19 | 北京煜鼎增材制造研究院有限公司 | Composite manufacturing method of ultra-large metal structure |
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US1987119A (en) * | 1932-06-20 | 1935-01-08 | Richard H Long | Heater for fluids |
US2616628A (en) * | 1948-06-22 | 1952-11-04 | Lloyd V Guild | Temperature controlled gas analysis apparatus |
US2820134A (en) * | 1953-05-06 | 1958-01-14 | Kobayashi Keigo | Heating apparatus |
US3229759A (en) * | 1963-12-02 | 1966-01-18 | George M Grover | Evaporation-condensation heat transfer device |
US3299196A (en) * | 1964-07-13 | 1967-01-17 | Electroglas Inc | Diffusion furnace |
US3311694A (en) * | 1965-05-28 | 1967-03-28 | Electroglas Inc | Diffusion furnace utilizing high speed recovery |
US3327772A (en) * | 1964-11-30 | 1967-06-27 | Kodaira Nobuhisa | Constant temperature heating apparatus using thermal medium vapor |
US3385921A (en) * | 1967-06-21 | 1968-05-28 | Electroglas Inc | Diffusion furnace with high speed recovery |
US3490718A (en) * | 1967-02-01 | 1970-01-20 | Nasa | Capillary radiator |
-
1969
- 1969-01-31 US US797725*A patent/US3651240A/en not_active Expired - Lifetime
- 1969-09-25 CA CA063,122A patent/CA971951A/en not_active Expired
- 1969-12-11 NL NL696918578A patent/NL154828B/en unknown
-
1970
- 1970-01-23 GB GB347770A patent/GB1304771A/en not_active Expired
- 1970-01-30 FR FR7003307A patent/FR2074806A1/en not_active Withdrawn
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US1987119A (en) * | 1932-06-20 | 1935-01-08 | Richard H Long | Heater for fluids |
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US2820134A (en) * | 1953-05-06 | 1958-01-14 | Kobayashi Keigo | Heating apparatus |
US3229759A (en) * | 1963-12-02 | 1966-01-18 | George M Grover | Evaporation-condensation heat transfer device |
US3299196A (en) * | 1964-07-13 | 1967-01-17 | Electroglas Inc | Diffusion furnace |
US3327772A (en) * | 1964-11-30 | 1967-06-27 | Kodaira Nobuhisa | Constant temperature heating apparatus using thermal medium vapor |
US3311694A (en) * | 1965-05-28 | 1967-03-28 | Electroglas Inc | Diffusion furnace utilizing high speed recovery |
US3490718A (en) * | 1967-02-01 | 1970-01-20 | Nasa | Capillary radiator |
US3385921A (en) * | 1967-06-21 | 1968-05-28 | Electroglas Inc | Diffusion furnace with high speed recovery |
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US3943964A (en) * | 1970-07-07 | 1976-03-16 | U.S. Philips Corporation | Heating device |
US3770047A (en) * | 1972-01-10 | 1973-11-06 | Trw | Apparatus for unidirectionally solidifying metals |
US3812908A (en) * | 1972-02-25 | 1974-05-28 | Philips Corp | Heat transferring device |
US3857990A (en) * | 1972-04-06 | 1974-12-31 | Massachusetts Inst Technology | Heat pipe furnace |
US4136733A (en) * | 1972-05-04 | 1979-01-30 | U.S. Philips Corporation | Heating device |
US3965334A (en) * | 1972-05-04 | 1976-06-22 | N.V. Philips Corporation | Heating device |
US4095647A (en) * | 1972-07-09 | 1978-06-20 | U.S. Philips Corporation | Heating device |
US3955618A (en) * | 1972-07-19 | 1976-05-11 | U.S. Philips Corporation | Heating device |
US4091264A (en) * | 1976-08-13 | 1978-05-23 | Seal Incorporated | Heat transfer |
US4585923A (en) * | 1982-09-23 | 1986-04-29 | Binder Peter M | Heating cabinet |
US4889276A (en) * | 1988-11-07 | 1989-12-26 | Rohr Industries, Inc. | Method and apparatus for forming and bonding metal assemblies |
US5164626A (en) * | 1990-06-14 | 1992-11-17 | Fujikura Ltd. | Coil element and heat generating motor assembled therefrom |
US5072094A (en) * | 1990-09-11 | 1991-12-10 | United States Department Of Energy | Tube furnace |
US7543630B2 (en) * | 2002-03-29 | 2009-06-09 | Fu Zhun Precision Industry (Shen Zhen) Co., Ltd. | Heat pipe incorporating outer and inner pipes |
US20060201656A1 (en) * | 2002-03-29 | 2006-09-14 | Hon Hai Precision Ind Co., Ltd. | Heat pipe incorporating outer and inner pipes |
US20050019234A1 (en) * | 2003-07-21 | 2005-01-27 | Chin-Kuang Luo | Vapor-liquid separating type heat pipe device |
US7051794B2 (en) * | 2003-07-21 | 2006-05-30 | Chin-Kuang Luo | Vapor-liquid separating type heat pipe device |
US7013955B2 (en) * | 2003-07-28 | 2006-03-21 | Thermal Corp. | Flexible loop thermosyphon |
US20060254753A1 (en) * | 2003-07-28 | 2006-11-16 | Phillips Alfred L | Flexible loop thermosyphon |
US20050024831A1 (en) * | 2003-07-28 | 2005-02-03 | Phillips Alfred L. | Flexible loop thermosyphon |
WO2005083345A1 (en) * | 2004-02-25 | 2005-09-09 | Thermal Corp | Flexible loop thermosyphon |
US20070107453A1 (en) * | 2005-11-16 | 2007-05-17 | Honeywell International Inc. | Heat exchanger with embedded heater |
US11641871B2 (en) | 2006-10-18 | 2023-05-09 | Rai Strategic Holdings, Inc. | Tobacco-containing smoking article |
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US20080121497A1 (en) * | 2006-11-27 | 2008-05-29 | Christopher Esterson | Heated/cool screw conveyor |
US20120153298A1 (en) * | 2007-02-16 | 2012-06-21 | Caracal, Inc. | Epitaxial growth system for fast heating and cooling |
US8430965B2 (en) * | 2007-02-16 | 2013-04-30 | Pronomic Industry Ab | Epitaxial growth system for fast heating and cooling |
US11849772B2 (en) | 2010-05-15 | 2023-12-26 | Rai Strategic Holdings, Inc. | Cartridge housing and atomizer for a personal vaporizing unit |
US11344683B2 (en) | 2010-05-15 | 2022-05-31 | Rai Strategic Holdings, Inc. | Vaporizer related systems, methods, and apparatus |
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US8784564B2 (en) * | 2010-06-29 | 2014-07-22 | Hon Hai Precision Industry Co., Ltd. | Film coating apparatus |
US20110315082A1 (en) * | 2010-06-29 | 2011-12-29 | Hon Hai Precision Industry Co., Ltd. | Film coating apparatus |
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US9689622B2 (en) * | 2012-04-25 | 2017-06-27 | Toshiba Mitsubishi-Electric Industrial Systems Corporation | Heat transfer device |
US20150075753A1 (en) * | 2012-04-25 | 2015-03-19 | Toshiba Mitsubishi-Electric Industrial Systems Corporation | Heat transfer device |
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US20160255681A1 (en) * | 2015-02-26 | 2016-09-01 | Inductive Engineering Technology, LLC | Magnetic induction heat engine and heat pipe delivery system and methods of producing and delivering heat |
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US11812536B2 (en) | 2019-06-10 | 2023-11-07 | Inductive Engineering Technology, LLC | Magnetic induction fluid heater |
Also Published As
Publication number | Publication date |
---|---|
CA971951A (en) | 1975-07-29 |
NL154828B (en) | 1977-10-17 |
FR2074806A1 (en) | 1971-10-08 |
DE1963560B2 (en) | 1975-07-03 |
GB1304771A (en) | 1973-01-31 |
DE1963560A1 (en) | 1970-07-23 |
NL6918578A (en) | 1970-08-04 |
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