US3880230A - Heat transfer system - Google Patents

Heat transfer system Download PDF

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US3880230A
US3880230A US366193A US36619373A US3880230A US 3880230 A US3880230 A US 3880230A US 366193 A US366193 A US 366193A US 36619373 A US36619373 A US 36619373A US 3880230 A US3880230 A US 3880230A
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heat
recited
transformer
working fluid
medium
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US366193A
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Richard L Pessolano
Robin B Rhodes
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Isothermics Inc
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Isothermics Inc
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Priority to US366193A priority Critical patent/US3880230A/en
Priority to CA186,008A priority patent/CA982533A/en
Priority to JP49014622A priority patent/JPS5016154A/ja
Priority to FR7415331A priority patent/FR2231929B1/fr
Priority to DE2425745A priority patent/DE2425745C3/en
Priority to US05/478,982 priority patent/US3994336A/en
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D21/00Heat-exchange apparatus not covered by any of the groups F28D1/00 - F28D20/00
    • F28D21/0001Recuperative heat exchangers
    • F28D21/0003Recuperative heat exchangers the heat being recuperated from exhaust gases
    • F28D21/0005Recuperative heat exchangers the heat being recuperated from exhaust gases for domestic or space-heating systems
    • F28D21/0008Air heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H6/00Combined water and air heaters
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28DHEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D15/00Heat-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
    • F28D15/02Heat-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
    • F28D15/0275Arrangements for coupling heat-pipes together or with other structures, e.g. with base blocks; Heat pipe cores
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10STECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00Superconductor technology: apparatus, material, process
    • Y10S505/825Apparatus per se, device per se, or process of making or operating same
    • Y10S505/90Heat exchange
    • Y10S505/901Heat pipe

Definitions

  • the present heat transfer system comprises a heat source; a heat pipe; a thermal transformer in thermal contact with said heat pipe and proximately disposed to said heat source; and a first chamber containing a medium with defined heat transfer characteristics. said chamber thermally coupled to said heat pipe; whereby a uniform heat transfer from said heat source to said medium is obtained.
  • the heat pipe can be utilized to significantly increase the efficiency of heat transfer. thereby obtaining a resultant minimization of undesired heat dissipation.
  • the heat pipe can transmit thermal energy at rates that are several hundred times greater than that of the best solid conductors, i.e.. silver. copper and gold. Additionally, a much lower power to weight ratio is attained in the use of the heat pipe.
  • This device is simple. has no moving parts. is inexpensive to manufacture. has a long if not indefinite life. and can be operated over an extended range oftemperatures.
  • the device is more accurately described as a miniaturized, hermetically sealed evaporating and condensing system.
  • the primary object of the present invention is to define at least one significant commercial application for this promising device.
  • the heat pipe consists essentially of a sealed container. a capillary wick structure which is secured to the interior surface of the container, and a quantity of working fluid sufficient to saturate the wick structure.
  • the container is sealed while under a vacuum.
  • the container is sealed under a vacuum.
  • the working fluid is in equilibrium with its own vapor.
  • any application of heat to any external surface of the heat pipe will cause an instantaneous evaporation of the working fluid near the heated surface.
  • the latent heat of vaporization is absorbed by the vapor.
  • the latent heat of vaporization is essentially the ratio of (a) the heat absorbed during the change of phase from liquid to vapor to (b) the mass of the system undergoing the change of phase. More technically speaking. the heat of vaporization is defined as the difference between the enthalpies of the system before and after the change of phase from liquid to vapor at constant temperature.
  • the vapor generated as a result of any heat addition creates a pressure gradient within the heat pipe which forces the excess vapor to an area of the heat pipe having a lower pressure and temperature.
  • the lower temperature causes the condensation of some vapor. thereby causing the latent heat of vaporization to be absorbed by the condenser surfaces of the heat pipe.
  • the heat may be removed from the condenser surfaces by conduction. convection or radiation to the surrounding environment.
  • the condensate is retuned to the evaporator region (area of heat addition) by the capillary pumping forces within the circumferential interior wick structure. This return may occur either with or without the aid of gravity.
  • the high efficiency of the heat pipe derives from the fact that the quantity of heat absorbed in the vaporization of a fluid is enormous compared to that absorbed during an increase in temperature of a fluid. For example. the amount of heat absorbed by 1 pound of water while being heated from 164 to 165 F. is l Btu. However, if the same pound of water were first vaporized at 164 F. and then the vapor heated to 165F.. the amount of heat absorbed would be l,000 Btu. Hence the same mass of water offers l.000 times the heat transfer capability over the same temperature gradient. when latent heat transfer is utilized.
  • Heat pipes can be designed to handle virtually any heat load and can be designed to operate over any temperature range. from below 300"Fv to above 3.630F.. by proper selection of the working fluid.
  • Heat pipe fluids have ranged from cryogenics such as nitrogen and helium. to liquid metals such as potassium and silver.
  • cryogenics such as nitrogen and helium.
  • liquid metals such as potassium and silver.
  • One of the most common fluids is water which has a useful operating range from 40 to 450 F.
  • a standard line of copper-water heat pipes is now commercially available. These heat pipes range in diameter from 3/l6 inch to l inch. and in length from 6 inches to 72 inches. The range of axial power ratings is from 60 watts to 1400 watts.
  • the present invention can be viewed as one of the first of what is believed will be virtually innumerable applications of the heat pipe concept. More particularly, the present invention constitutes an attempt to (a) reduce heat losses, (b) increase heating efficiency in domestic heating systems. and (c) at the same time, to eliminate the duplication of system components such as now exists in gas, oil. or coal systems with separate hot water heaters. and separate air-conditioning systems.
  • the present invention in its application to domestic heating systems. comprises a heat transfer system having three basic sections: a primary heat transformer, a hot water chamber, and a hot air chamber. In addition to these three basic sections. there is an additional fundamental system component, that of a plurality of heat pipes which thermally connect said hot water chamber and said hot air chamber to said primary heat transformer.
  • chamber shall be hereafter applied to any distinct and separate region of the system into or through which pass a plurality of heat pipes, which thermally connect said region with another region of the system, and the primary purpose of said region is to permit heat to be transferred to or from said plurality of heat pipes. from or to some medium with defined heat transfer properties which may reside within or pass through said region.
  • the transformer can be powered by any type of heat source. From the transformer, heat enters the heat pipes which in turn direct the thermal energy toward both the water and air chambers.
  • the water tank serves three functions: first, as a source of domestic hot water; second, as a thermal capacitor; and third, as a burner control.
  • the burner will shut down when the water tank reaches a predetermined temperature. Since the hot water section is connected by heat pipes to the hot air section, the water tank will serve as an additional source of heat for the hot air section when the burner is off. This represents an efficiency in heat use that does not exist in prior art systems.
  • the burner will reignite.
  • the hot air flow is regulated by a room thermostat which controls a two-speed fan.
  • the fan has a low speed to supply a constant trickle of warm air, and a high speed to provide additional heat when required.
  • the fan controls are completely independent from the burner.
  • This mode of operation eliminates the type of large temperature variations that are common in present systems.
  • the water tank as a thermal capacitor, it is possible to reduce overall burner running time and to change the burning cycle from many short runs to fewer, longer runs per day. Fewer starts and stops reduce burner exhaust pollution as well as system maintenance costs, as compared to the higher frequency conventional burner cycles.
  • FIG. 1 is a cross-sectional schematic view of a heat pipe.
  • FIG. 2 is a systems view of one embodiment of the present invention.
  • FIG. 3 is a cross-sectional radial schematic view of the transformer.
  • FIG. 4 is a cutaway perspective view of a domestic heating system utilizing the principles of the present invention.
  • FIG. 5 is a schematic view of a residential climate control system embodying the present invention.
  • FIG. 1 a single heat pipe in schematic form.
  • the pipe in the illustrated embodiment, comprises a closed elongated cylindrical container 9 containing a working fluid ll and a capillary wick structure 12 which is cirumferentially secured to the interior surface of the pipe 10.
  • Region I3 is termed the evaporator end of the pipe. It is at this end that heat is added to the present system, thereby causing evaporation of the fluid ll or the formation of vapor ll and movement of said vapor axially to the right and toward a cooler area 14 of the pipe having a lower pressure.
  • Area 14 comprises the condenser end of the pipe.
  • the vapor 11' is condensed, thus releasing its latent heat.
  • the fluid ll is absorbed into the wick structure 12 and is returned, by capillary forces, to the evaporator end 13 where the above cycle can be repeated indefinitely.
  • Section 15 is variously termed as a transport and an adiabutic section. In essence, this terminology means that section 15 functions to effect an efficient transfer of the vaporized fluid from sections 13 to 14, and the condensed vapor from sections 14 to 13.
  • FIG. 2 presents a systems illustration of one embodiment of the present invention. Shown is a multichambered heat transfer system which utilizies heat pipes to thermally connect several separate chambers.
  • the number, size, shape, construction and relative orientation of the separate chambers may be varied in any manner whatsoever to accommodate virtually any type of heating or cooling problem.
  • the heat pipes, their number, shape, size, orientation, construction and internal working mechanisms can be varied wherever necessary to achieve a solution to a particular heating or cooling problem.
  • the present invention is similarly intended to be readily adaptable to use with any source of heat and with virtually any heating load.
  • the primary mode of heat transfer is through the evaporation and condensation of a working fluid in a thermal transformer 18, and in one or more of the heat pipes 20, 22, 24 and 25.
  • the transformer 18 functions to convert or transform the high and non-uniform heat fluxes typical on the exterior of said transformer, into lower and more uniform heat fluxes.
  • Said heat pipes serve as thermal connectors and as heat transfer mediums to the several chambers 26, 28, 30 and 32. Secondary heat transfer can be obtained by ancillary heat pipes 33 disposed within or between said chambers 26, 28, 30 and 32.
  • the working fluid utilized within the transformer 18 need not necessarily be the same as the working fluid utilized within said heat pipes in said chambers.
  • All containment materials, and other materials in the inventions construction may be varied in any manner and are limited only with regard to their chemical compatability with each other and with the different materials with which they may come into contact.
  • This constraint pertains to the working fluids employed in the invention and its component parts.
  • both the working fluids, and their respective containment materials have a common limitation in that the structural integrity of said containments must withstand the operating temperatures and resultant operating pressures of the respective fluids.
  • Heat may be transferred through and/or from the transformer 18, to one or more of several chambers 26 through 32. These several chambers are intended to be sealed from each other in a suitable manner with, under the worst design and external conditions, no mass transfer occurring from one chamber to any other chamber, except where a mass transfer is intended as a part of a heat transfer process.
  • An ultimate heat source 34 is intended to supply the primary heat in required amounts to the invention.
  • the heat source 34 is applied to the transformer 18. It is, however, to be emphasized that alternate arrangements could be equally suitable in any given application. For example, the system of FIG. 2 could, with minor adaptations, have the heat source 34 applied to one of the chambers 26 through 32.
  • the chamber to which the heat source 34 is applied should contain, in addition to its enclosing walls, a working fluid (which may from time to time be frozen) and its vapor, as well as evaporation surfaces, condensation surfaces, a pressure release safety valve, and any temperature and/or pressure sensitive control devices that may be required in the solving ofa particular heating problem.
  • the primary purpose in the use of a transformer as opposed to the direct application of the heat source 34 to the evaporator ends of the heat pipes through 26, is to create a uniformity in the heat flux (noted by the four arrows in FIG. 2) from the heat source 34 to the chambers (26 through 32).
  • the transformer 18 also serves to reduce the possibility of a phenomenon which is known as heat pipe burnout. Heat pipe burnout occurs when the rate of evaporation in the evaporator section exceeds the rate of condensate return to the evaporator section, and the evaporator becomes dried out. In such a condition, a heat pipe cannot function.
  • FIG. 2 need comprise only a single heat pipe.
  • experimentation has shown that a more efficient operation can be obtained where a plurality of heat pipes are enclosed within the transformer 18.
  • FIG. 3 A representative configuration of such multiple heat pipes, enclosed with the transformer, is illustrated in FIG. 3.
  • a Y-shaped channel 36 (see FIG. 3) is termed a percolation channel.
  • a collector 37 serves to collect vapor bubbles which provide the means to pump working fluid via the percolation channel to the upper extremities of the wick structure. In doing so, the burnout heat flux of the transfomer evaporation surface is greatly increased because of this added condensate return mechanism.
  • An additional condensate return mechanism that of the gravity return of condensate from the condenser surface, is aided by the use of parallel radial fins 38 on the heat pipes. Said parallel radial fins, when spaced properly, aid the condensate return as a result of a miniscus which forms between adjacent fins, and on the lower surfaces, with respect to gravity. As droplets fall from said lower surfaces, surface tension forces resultant from said miniscus serve to draw condensate in the form of a falling film from the upper surfaces of said parallel fins. It is believed that this phenomenon can increase the heat transfer due to condensation on the underside of a horizontal surface by as much as five fold as compared to condensation without formation of said miniscus and its resultant surface tension forces. The primary reason for increased heat transfer is the reduc tion of the film thickness as a result of this falling film phenomenon.
  • FIG. 3 It has also been found that the design of FIG. 3 will operate at maximum efficiency where each pipe 10 is aligned in its own vertical plane. Such alignment provides each pipe with its own dripping path to the region 40. Hence, the fluid transport process within the transformer 18 is further assisted.
  • Heat may enter the transformer by means of conduction through one or more of its walls, and then through evaporator surface 42. See FIG. 3. Since the working fluid and its vapor are in a state of equilibrium at a reduced pressure, the addition of any heat to chamber 18 will cause a shift in the equilibrium state, favoring the evaporation of the working fluid. When this occurs, the latent heat of vaporization of the working fluid is transferred to the heat pipes by the condensation of vapor on said heat pipes exterior surfaces. The heat is then transferred axially away from the transformer by the internal dynamics of said heat pipes.
  • the heat deposited in regions 14' of said heat pipes 10 will conduct through the wall of said heat pipes 10 in regions 14' disposed within chambers 26, 28, 30 and 32, and then transfer from the exterior surfaces of the heat pipes 10 to the mediums contained within chambers 26, 28, 30 and 32, in a manner which is extremely efficient and uniform.
  • source 34 is inactive, and that one or more of the media contained within chambers 26, 28, 30 and 32 reside at a temperature which is different from the temperature at which one medium within one of the chambers resides at. said temperature gradient is sufficient to promote heat transfer from a medium residing at higher temperature to a medium residing at lower temperature.
  • Heat transfer to the media contained within chambers 26 to 32 of the system of FIG. 2 from the thermally connective heat pipes may be effected by any transfer means, that is. by conduction. convection, radiation. or the evaporation and condensation of a working fluid. or any combination of these.
  • the thermally connective heat pipes 10 may be variously smooth. rough. or finned in any manner so as to regulate the heat transfer to or from a heat pipe surface and from or to the medium in contact with said surface.
  • transfomer l8 and its associated plurality of heat pipes may serve as a means of thermally linking, and thereby thermally powering, any heating or cooling system.
  • the hereinafter described embodiment represents but one of a multiplicity of systems to which the present concept may be readily adapted.
  • one or more of the several chambers may be in the form of an air duct 26' designed so as to allow the passage of various quantities of air 44 or any other suitable gas, through the duct 26.
  • Said air 44 is in thermal contact with the exterior surface of the heat pipes 10 which extend into chamber 26'.
  • the intent of such a chamber is to raise or lower the temperature of the air 44 flowing through it.
  • the system will be equipped with air moving equipment. air flow controls, with temperature controls. and with any other control deemed necessary for the solution of a particular heat transfer problem.
  • One or more of the several chambers may contain a medium. with defined thermodynamic properties. which has the ability to store heat energy. either by virtue of increasing the temperature of said medium (sensible energy storage) or by virtue of changing the phase of said medium, either from solid to liquid, or from liquid to vapor (latent energy storage), or by virtue of a combination of these two (sensible and latent energy storage).
  • Said chamber can be termed a thermal battery, or a thermal capacitor.
  • Such a chamber may be in the form of a water tank 30'. as is illustrated in FIG. 4.
  • the intent of the tank 30' (in addition to its obvious use as a tank for supplying hot water for domestic use) is to absorb and store thermal energy, from the transformer I8, that is not immediately being utilized by the domestic hot water and hot air system. Energy absorbed by the tank 30'. is available for immediate use. either as instantaneous domestic hot water, or by virtue of the thermally connective heat pipes, as instantaneous hot air for domestic heat. regardless of whether the ultimate heat source is functioning or not.
  • One or more of the several chambers may comprise a geometric configuration similar to interchangeable with. or in place of the generator of an absorption refrigeration system of suitable size to be powered by the energy which could be provided by said chamber. It is not intended that an absorption refrigeration system is a part of this invention; however, it is intended that an appropriately sized absorption refrigeration system can be powered by a suitably designed chamber of said invention.
  • Such a suitably designed chamber 28 or 32 of said invention when serving to power such an appropriately sized absorption system can be considered to provide a means for removing heat energy from a second chamber. which may be an integral part of the invention, by virtue of the direct application of the absorption refrigeration system evaporating coil to that chamber. Said chamber could provide means for cooling air. water or any other medium used within the present system.
  • the residential heating system shown in FIGS. 4 and 5 includes a stack 46 for venting products of combustion from the heat source 34'. Also shown is a chimney 48.
  • the stack 46 receives the products combustion through the circumferential channel 50 (shown in FIG. 3).
  • Hot water for household use is. as above noted, supplied from the tank 30' (shown in FIG. 4).
  • An air exchange system and duct network for conditioning residential air comprises the duct for supplying air and an air return 52.
  • the air is circulated, by a fan 54, past a portion of the hot air chamber 26.
  • the heated air is thereby supplied through air supply 56 and to the individual room heat vents 58.
  • a typical operation cycle would be as follows: The water in tank 30' will be initially heated to 200F. A blower 54 will run at a low speed, sufficient to transfer an amount of heat from the transformer I8 through the air supply duct 56 and into the individual room vents 58, thereby compensating for heat losses through the domestic structure. With the heat source 34' off, heat is supplied to the air supply 44 via heat pipe 10 from 30' of the system. That is. the hot air chamber 26' will draw upon the thermal energy stored within the hot water chamber 30. This illustrates, in one form, the above-described thermal battery properties of the chamber 30.
  • an aquastat 62 When the temperature within the chamber 30' is reduced to l40 F.. an aquastat 62 will reactivate heat source 34'. Said heat source will supply heat through the transformer 18' for both the air and water supplied to the present domestic system. (The source 34' will operate until the water in tank 30' reaches 200 F, at which point the aquastat 62 will turn off the heat source.) In order to compensate for what is often a variable demand for heat within the rooms. a room thermostat 64 is provided which will control the speed of the fan 54, thereby regulating the rate at which heat is drawn from the chamber 26 for delivery to the rooms.
  • a tempering valve 66 may be employed to provide domestic hot water at one specified temperature, perhaps F.
  • Such a valve contains a thermal sensor which regulates the mixing ratio of hot water and cold water input to obtain a constant temperature output.
  • a heat transfer system comprising:
  • thermo transformer thermally linked to both said heat pipes and said heat source.
  • said transformer comprising:
  • said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
  • a second chamber containing a second medium with defined thermodynamic properties said second medium thermally connected to said first chamber by said ancillary heat pipe.
  • said heat pipe comprises a plurality of heat pipes, each of said heat pipes being disposed in a vertical plane that does not intersect the vertical plane of any other of said heat pipes.
  • said heat source comprises: an exothermic chemical heat source.
  • a heat transfer system comprising:
  • thermal transformer thermally linked to both said heat pipe and said heat source, said thermal transformer comprising:
  • a first chamber containing a first medium with defined heat transfer characteristics and residing at a first temperature, said first chamber thermally coupled to said first end of said heat pipe;
  • a second chamber containing a second medium with defined heat transfer characteristics and residing at a second temperature, said second chamber chamber thermally coupled to said second end of said heat pipe,
  • the system as recited in claim 17 is which said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
  • heat source comprises an electric heating element disposed externally proximate said transformer.

Abstract

The present heat transfer system comprises a heat source; a heat pipe; a thermal transformer in thermal contact with said heat pipe and proximately disposed to said heat source; and a first chamber containing a medium with defined heat transfer characteristics, said chamber thermally coupled to said heat pipe; whereby a uniform heat transfer from said heat source to said medium is obtained.

Description

United States Patent [191 Pessolano et a1.
1 1 HEAT TRANSFER SYSTEM [75] Inventors: Richard L. Pessolano, Sparta; Robin B. Rhodes, Parsippany, both of NJ.
173] Assignee: lsothermics Incorporated. Clifton.
1221 Filed: June 1. 1973 [21] Appl. No: 366.193
152] U.S. Cl .1 165/105; 126/99 R;126/101; 237/19; 237/53; 165/63; 165/64 [51] Int. Cl. F28d 15/00 [58] Field of Search l65/105.63.64;126/101. 126/99 R; 237/19. 53
[561 References Cited UNITED STATES PATENTS 2.237.054 4/1941 Jensen 126/101 3.581.347 1/1952 Buckstrom U 165/105 X 1 Apr. 29, 1975 3.152.774 10/1964 Wyatt 165/105 X 3.180.405 4/1965 Hinde 3.517.730 6/1970 Wyatt 3.621.906 11/1971 Leffcrt 3.702.533 11/1973 Dirnc ct a1 165/105 X 3.746.079 7/1973 Arenson .7 165/105 X Primary Examiner-Albert W. Davis. Jr. Attorney. Agent. or Firm-Mel K. Silverman. Esq.
1571 ABSTRACT The present heat transfer system comprises a heat source; a heat pipe; a thermal transformer in thermal contact with said heat pipe and proximately disposed to said heat source; and a first chamber containing a medium with defined heat transfer characteristics. said chamber thermally coupled to said heat pipe; whereby a uniform heat transfer from said heat source to said medium is obtained.
31 Claims. 5 Drawing Figures HEAT TRANSFER SYSTEM BACKGROUND OF INVENTION in recent years. a major effort has been mounted in an attempt to find more efficient methods for the transport of thermal energy. This effort derives from the fact that the problem of heat loss or waste has become one of the major areas of concern in our highly technological society.
A promising new device has evolved from these studies which has the potential to revolutionize the heat transfer industry. This new device. termed the heat pipe. can be utilized to significantly increase the efficiency of heat transfer. thereby obtaining a resultant minimization of undesired heat dissipation. The heat pipe can transmit thermal energy at rates that are several hundred times greater than that of the best solid conductors, i.e.. silver. copper and gold. Additionally, a much lower power to weight ratio is attained in the use of the heat pipe.
This device is simple. has no moving parts. is inexpensive to manufacture. has a long if not indefinite life. and can be operated over an extended range oftemperatures.
The basic principles of the heat pipe were developed by Richard S. Gaugler of General Motors Corporation some years ago. However, no effort was made to put these principles to work until I963 when the National Aeronautics and Space Administration was faced with the need for a superconductor of thermal energy. The device now known in the art as the heat pipe was developed at the University of California by a team of research scientists headed by Dr. George L. Grover.
Sometimes compared to a steam heating system, the device is more accurately described as a miniaturized, hermetically sealed evaporating and condensing system.
Until recently. only exotic applications such as NASA'S use of the device as a cooling means for electronic components in space, have been considered for the heat pipe. Accordingly, the primary object of the present invention is to define at least one significant commercial application for this promising device.
The heat pipe consists essentially of a sealed container. a capillary wick structure which is secured to the interior surface of the container, and a quantity of working fluid sufficient to saturate the wick structure. The container is sealed while under a vacuum.
Because the container is sealed under a vacuum. the working fluid is in equilibrium with its own vapor. Thus. any application of heat to any external surface of the heat pipe will cause an instantaneous evaporation of the working fluid near the heated surface. In the vaporization process, the latent heat of vaporization is absorbed by the vapor.
The latent heat of vaporization is essentially the ratio of (a) the heat absorbed during the change of phase from liquid to vapor to (b) the mass of the system undergoing the change of phase. More technically speaking. the heat of vaporization is defined as the difference between the enthalpies of the system before and after the change of phase from liquid to vapor at constant temperature.
The vapor generated as a result of any heat addition creates a pressure gradient within the heat pipe which forces the excess vapor to an area of the heat pipe having a lower pressure and temperature. The lower temperature causes the condensation of some vapor. thereby causing the latent heat of vaporization to be absorbed by the condenser surfaces of the heat pipe. The heat may be removed from the condenser surfaces by conduction. convection or radiation to the surrounding environment.
The condensate is retuned to the evaporator region (area of heat addition) by the capillary pumping forces within the circumferential interior wick structure. This return may occur either with or without the aid of gravity.
There are. as aforestated. only three basic components to any heat pipe: the container, the wick and the fluid. This extreme simplicity. taken in complement with the fact of the absence of any moving mechanical parts. has demanded that the heating and refrigeration industries pay far greater heed to heat pipe technology. The high efficiency of the heat pipe derives from the fact that the quantity of heat absorbed in the vaporization of a fluid is enormous compared to that absorbed during an increase in temperature of a fluid. For example. the amount of heat absorbed by 1 pound of water while being heated from 164 to 165 F. is l Btu. However, if the same pound of water were first vaporized at 164 F. and then the vapor heated to 165F.. the amount of heat absorbed would be l,000 Btu. Hence the same mass of water offers l.000 times the heat transfer capability over the same temperature gradient. when latent heat transfer is utilized.
Heat pipes can be designed to handle virtually any heat load and can be designed to operate over any temperature range. from below 300"Fv to above 3.630F.. by proper selection of the working fluid. Heat pipe fluids have ranged from cryogenics such as nitrogen and helium. to liquid metals such as potassium and silver. One of the most common fluids is water which has a useful operating range from 40 to 450 F.
A standard line of copper-water heat pipes is now commercially available. These heat pipes range in diameter from 3/l6 inch to l inch. and in length from 6 inches to 72 inches. The range of axial power ratings is from 60 watts to 1400 watts.
SUMMARY OF THE INVENTIQN The present invention can be viewed as one of the first of what is believed will be virtually innumerable applications of the heat pipe concept. More particularly, the present invention constitutes an attempt to (a) reduce heat losses, (b) increase heating efficiency in domestic heating systems. and (c) at the same time, to eliminate the duplication of system components such as now exists in gas, oil. or coal systems with separate hot water heaters. and separate air-conditioning systems.
The present invention in its application to domestic heating systems. comprises a heat transfer system having three basic sections: a primary heat transformer, a hot water chamber, and a hot air chamber. In addition to these three basic sections. there is an additional fundamental system component, that of a plurality of heat pipes which thermally connect said hot water chamber and said hot air chamber to said primary heat transformer.
The terms heat transformer, thermal transformer. and transformer" shall be hereafter applied to any chamber of the system which acts primarily as a thermal link between any heat source external to the system and the system, and in which the principal means of heat transfer shall be the evaporation or boiling of a working fluid contained within said chamber followed by the condensation of said working fluid upon the exterior surfaces of a plurality of heat pipes, which thermally connect said chamber with another chamber of the system.
The term chamber" shall be hereafter applied to any distinct and separate region of the system into or through which pass a plurality of heat pipes, which thermally connect said region with another region of the system, and the primary purpose of said region is to permit heat to be transferred to or from said plurality of heat pipes. from or to some medium with defined heat transfer properties which may reside within or pass through said region.
The transformer can be powered by any type of heat source. From the transformer, heat enters the heat pipes which in turn direct the thermal energy toward both the water and air chambers. In a typical system the water tank serves three functions: first, as a source of domestic hot water; second, as a thermal capacitor; and third, as a burner control. In a characteristic mode of operation, the burner will shut down when the water tank reaches a predetermined temperature. Since the hot water section is connected by heat pipes to the hot air section, the water tank will serve as an additional source of heat for the hot air section when the burner is off. This represents an efficiency in heat use that does not exist in prior art systems. When the temperature of the tank water drops below a second predetermined temperature, the burner will reignite.
The hot air flow is regulated by a room thermostat which controls a two-speed fan. The fan has a low speed to supply a constant trickle of warm air, and a high speed to provide additional heat when required. The fan controls are completely independent from the burner.
This mode of operation eliminates the type of large temperature variations that are common in present systems. By using the water tank as a thermal capacitor, it is possible to reduce overall burner running time and to change the burning cycle from many short runs to fewer, longer runs per day. Fewer starts and stops reduce burner exhaust pollution as well as system maintenance costs, as compared to the higher frequency conventional burner cycles.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional schematic view of a heat pipe.
FIG. 2 is a systems view of one embodiment of the present invention.
FIG. 3 is a cross-sectional radial schematic view of the transformer.
FIG. 4 is a cutaway perspective view of a domestic heating system utilizing the principles of the present invention.
FIG. 5 is a schematic view of a residential climate control system embodying the present invention.
DETAILED DESCRIPTION OF THE INVENTION In FIG. 1 is illustrated a single heat pipe in schematic form. The pipe, in the illustrated embodiment, comprises a closed elongated cylindrical container 9 containing a working fluid ll and a capillary wick structure 12 which is cirumferentially secured to the interior surface of the pipe 10. Region I3 is termed the evaporator end of the pipe. It is at this end that heat is added to the present system, thereby causing evaporation of the fluid ll or the formation of vapor ll and movement of said vapor axially to the right and toward a cooler area 14 of the pipe having a lower pressure. Area 14 comprises the condenser end of the pipe. It is at this end that the vapor 11' is condensed, thus releasing its latent heat. On condensation. the fluid ll is absorbed into the wick structure 12 and is returned, by capillary forces, to the evaporator end 13 where the above cycle can be repeated indefinitely.
Section 15 is variously termed as a transport and an adiabutic section. In essence, this terminology means that section 15 functions to effect an efficient transfer of the vaporized fluid from sections 13 to 14, and the condensed vapor from sections 14 to 13.
FIG. 2 presents a systems illustration of one embodiment of the present invention. Shown is a multichambered heat transfer system which utilizies heat pipes to thermally connect several separate chambers. The number, size, shape, construction and relative orientation of the separate chambers may be varied in any manner whatsoever to accommodate virtually any type of heating or cooling problem. Similarly, the heat pipes, their number, shape, size, orientation, construction and internal working mechanisms can be varied wherever necessary to achieve a solution to a particular heating or cooling problem. The present invention is similarly intended to be readily adaptable to use with any source of heat and with virtually any heating load.
The primary mode of heat transfer is through the evaporation and condensation of a working fluid in a thermal transformer 18, and in one or more of the heat pipes 20, 22, 24 and 25. The transformer 18 functions to convert or transform the high and non-uniform heat fluxes typical on the exterior of said transformer, into lower and more uniform heat fluxes. Said heat pipes serve as thermal connectors and as heat transfer mediums to the several chambers 26, 28, 30 and 32. Secondary heat transfer can be obtained by ancillary heat pipes 33 disposed within or between said chambers 26, 28, 30 and 32.
It is to be noted that the working fluid utilized within the transformer 18 need not necessarily be the same as the working fluid utilized within said heat pipes in said chambers.
All containment materials, and other materials in the inventions construction, may be varied in any manner and are limited only with regard to their chemical compatability with each other and with the different materials with which they may come into contact. This constraint pertains to the working fluids employed in the invention and its component parts. In addition, both the working fluids, and their respective containment materials, have a common limitation in that the structural integrity of said containments must withstand the operating temperatures and resultant operating pressures of the respective fluids.
Heat may be transferred through and/or from the transformer 18, to one or more of several chambers 26 through 32. These several chambers are intended to be sealed from each other in a suitable manner with, under the worst design and external conditions, no mass transfer occurring from one chamber to any other chamber, except where a mass transfer is intended as a part of a heat transfer process.
An ultimate heat source 34, whether this source be a gas flame, an oil burner fire box, an electric heater, or any other source of thermal energy, is intended to supply the primary heat in required amounts to the invention. In the embodiment illustrated in FIG. 2, the heat source 34 is applied to the transformer 18. It is, however, to be emphasized that alternate arrangements could be equally suitable in any given application. For example, the system of FIG. 2 could, with minor adaptations, have the heat source 34 applied to one of the chambers 26 through 32.
The chamber to which the heat source 34 is applied should contain, in addition to its enclosing walls, a working fluid (which may from time to time be frozen) and its vapor, as well as evaporation surfaces, condensation surfaces, a pressure release safety valve, and any temperature and/or pressure sensitive control devices that may be required in the solving ofa particular heating problem.
The primary purpose in the use of a transformer as opposed to the direct application of the heat source 34 to the evaporator ends of the heat pipes through 26, is to create a uniformity in the heat flux (noted by the four arrows in FIG. 2) from the heat source 34 to the chambers (26 through 32). In addition to providing the present system with a uniformity in its heat gradient, the transformer 18 also serves to reduce the possibility of a phenomenon which is known as heat pipe burnout. Heat pipe burnout occurs when the rate of evaporation in the evaporator section exceeds the rate of condensate return to the evaporator section, and the evaporator becomes dried out. In such a condition, a heat pipe cannot function.
In theory, the system shown in FIG. 2 need comprise only a single heat pipe. However, experimentation has shown that a more efficient operation can be obtained where a plurality of heat pipes are enclosed within the transformer 18. A representative configuration of such multiple heat pipes, enclosed with the transformer, is illustrated in FIG. 3.
A Y-shaped channel 36 (see FIG. 3) is termed a percolation channel. A collector 37 serves to collect vapor bubbles which provide the means to pump working fluid via the percolation channel to the upper extremities of the wick structure. In doing so, the burnout heat flux of the transfomer evaporation surface is greatly increased because of this added condensate return mechanism.
An additional condensate return mechanism, that of the gravity return of condensate from the condenser surface, is aided by the use of parallel radial fins 38 on the heat pipes. Said parallel radial fins, when spaced properly, aid the condensate return as a result of a miniscus which forms between adjacent fins, and on the lower surfaces, with respect to gravity. As droplets fall from said lower surfaces, surface tension forces resultant from said miniscus serve to draw condensate in the form of a falling film from the upper surfaces of said parallel fins. It is believed that this phenomenon can increase the heat transfer due to condensation on the underside of a horizontal surface by as much as five fold as compared to condensation without formation of said miniscus and its resultant surface tension forces. The primary reason for increased heat transfer is the reduc tion of the film thickness as a result of this falling film phenomenon.
It has also been found that the design of FIG. 3 will operate at maximum efficiency where each pipe 10 is aligned in its own vertical plane. Such alignment provides each pipe with its own dripping path to the region 40. Hence, the fluid transport process within the transformer 18 is further assisted.
Heat may enter the transformer by means of conduction through one or more of its walls, and then through evaporator surface 42. See FIG. 3. Since the working fluid and its vapor are in a state of equilibrium at a reduced pressure, the addition of any heat to chamber 18 will cause a shift in the equilibrium state, favoring the evaporation of the working fluid. When this occurs, the latent heat of vaporization of the working fluid is transferred to the heat pipes by the condensation of vapor on said heat pipes exterior surfaces. The heat is then transferred axially away from the transformer by the internal dynamics of said heat pipes.
Thus, heat transferred through the evaporator surface 42 as a result of a finite temperature difference across the surface 42, will cause portions of the working fluid 41 to vaporize or boil immediately, absorbing the latent heat of vaporization of fluid 41 in doing so. As a result of the pressure gradient induced by said vapor formation, the vapor 41 is forced into regions of lower pressure, and consequently lower temperature. Within the transformer 18, these regions of lower pressure and temperature are in the vicinity of the heat pipes 10 which pass through said transformer. Because the heat pipes 10 are at an equilibrium temperature which is lower than that of the newly created vapor 41', said newly created vapor 41' will condense on the exterior finned surfaces 38 of said heat pipes 10, and in doing so, deposit the latent heat of vaporization of said working fluid 41 on said finned surfaces 38.
Thus the heat transferred to the finned surfaces 38 as a result of a finite temperature difference across evaporator surface 42, will conduct through the heat pipe wall 9 and cause portions of the working fluid 11 contained within heat pipes 10 to vaporize or boil immediately, absorbing the latent heat of vaporization of fluid 11 in doing so. As a result of the pressure gradient induced by said vapor formation, the vapor 11' is forced into regions, within said heat pipes 10, of lower pressure and consequently lower temperature. These regions of lower pressure and temperature coresponding to condenser section 14 of FIG. 1, are disposed within the chambers 26, 28, 30 and 32 of FIG. 2. Because these condenser sections 14' disposed within the chambers 26, 28, 30 and 32 are at an equilibrium temperature which is less than that of the newly created vapor 11' said'newly created vapor 11', will condense on the interior surfaces of heat pipes 10 in regions denoted by 14' of FIG. 4, and in doing so deposit the latent heat of vaporization of said working fluid II in said condenser regions 14.
The heat deposited in regions 14' of said heat pipes 10 will conduct through the wall of said heat pipes 10 in regions 14' disposed within chambers 26, 28, 30 and 32, and then transfer from the exterior surfaces of the heat pipes 10 to the mediums contained within chambers 26, 28, 30 and 32, in a manner which is extremely efficient and uniform.
In the event that source 34 is inactive, and that one or more of the media contained within chambers 26, 28, 30 and 32 reside at a temperature which is different from the temperature at which one medium within one of the chambers resides at. said temperature gradient is sufficient to promote heat transfer from a medium residing at higher temperature to a medium residing at lower temperature.
Heat transfer to the media contained within chambers 26 to 32 of the system of FIG. 2 from the thermally connective heat pipes may be effected by any transfer means, that is. by conduction. convection, radiation. or the evaporation and condensation of a working fluid. or any combination of these. In attaining said various heat transfer modes. the thermally connective heat pipes 10 may be variously smooth. rough. or finned in any manner so as to regulate the heat transfer to or from a heat pipe surface and from or to the medium in contact with said surface.
It is to be noted that certain thermal sources. such as electrical heat, could be applied to transformer 18 by the placement of heating elements inside of said transformer. This design would be in distinction from the il lustrated embodiment wherein the ultimate heat source 34 is applied externally.
It is to be understood that the transfomer l8 and its associated plurality of heat pipes may serve as a means of thermally linking, and thereby thermally powering, any heating or cooling system. Viewed in this light, it can be appreciated that the hereinafter described embodiment represents but one of a multiplicity of systems to which the present concept may be readily adapted.
Turning now to FIG. 4, we see that one or more of the several chambers may be in the form of an air duct 26' designed so as to allow the passage of various quantities of air 44 or any other suitable gas, through the duct 26. Said air 44 is in thermal contact with the exterior surface of the heat pipes 10 which extend into chamber 26'. The intent of such a chamber is to raise or lower the temperature of the air 44 flowing through it. In conjunction with chamber 26' the system will be equipped with air moving equipment. air flow controls, with temperature controls. and with any other control deemed necessary for the solution of a particular heat transfer problem.
One or more of the several chambers may contain a medium. with defined thermodynamic properties. which has the ability to store heat energy. either by virtue of increasing the temperature of said medium (sensible energy storage) or by virtue of changing the phase of said medium, either from solid to liquid, or from liquid to vapor (latent energy storage), or by virtue of a combination of these two (sensible and latent energy storage). Said chamber can be termed a thermal battery, or a thermal capacitor.
Such a chamber may be in the form of a water tank 30'. as is illustrated in FIG. 4. The intent of the tank 30' (in addition to its obvious use as a tank for supplying hot water for domestic use) is to absorb and store thermal energy, from the transformer I8, that is not immediately being utilized by the domestic hot water and hot air system. Energy absorbed by the tank 30'. is available for immediate use. either as instantaneous domestic hot water, or by virtue of the thermally connective heat pipes, as instantaneous hot air for domestic heat. regardless of whether the ultimate heat source is functioning or not.
One or more of the several chambers may comprise a geometric configuration similar to interchangeable with. or in place of the generator of an absorption refrigeration system of suitable size to be powered by the energy which could be provided by said chamber. It is not intended that an absorption refrigeration system is a part of this invention; however, it is intended that an appropriately sized absorption refrigeration system can be powered by a suitably designed chamber of said invention.
Such a suitably designed chamber 28 or 32 of said invention. when serving to power such an appropriately sized absorption system can be considered to provide a means for removing heat energy from a second chamber. which may be an integral part of the invention, by virtue of the direct application of the absorption refrigeration system evaporating coil to that chamber. Said chamber could provide means for cooling air. water or any other medium used within the present system.
The residential heating system shown in FIGS. 4 and 5 includes a stack 46 for venting products of combustion from the heat source 34'. Also shown is a chimney 48.
The stack 46 receives the products combustion through the circumferential channel 50 (shown in FIG. 3). Hot water for household use is. as above noted, supplied from the tank 30' (shown in FIG. 4). An air exchange system and duct network for conditioning residential air comprises the duct for supplying air and an air return 52. The air is circulated, by a fan 54, past a portion of the hot air chamber 26. The heated air is thereby supplied through air supply 56 and to the individual room heat vents 58.
A typical operation cycle would be as follows: The water in tank 30' will be initially heated to 200F. A blower 54 will run at a low speed, sufficient to transfer an amount of heat from the transformer I8 through the air supply duct 56 and into the individual room vents 58, thereby compensating for heat losses through the domestic structure. With the heat source 34' off, heat is supplied to the air supply 44 via heat pipe 10 from 30' of the system. That is. the hot air chamber 26' will draw upon the thermal energy stored within the hot water chamber 30. This illustrates, in one form, the above-described thermal battery properties of the chamber 30.
When the temperature within the chamber 30' is reduced to l40 F.. an aquastat 62 will reactivate heat source 34'. Said heat source will supply heat through the transformer 18' for both the air and water supplied to the present domestic system. (The source 34' will operate until the water in tank 30' reaches 200 F, at which point the aquastat 62 will turn off the heat source.) In order to compensate for what is often a variable demand for heat within the rooms. a room thermostat 64 is provided which will control the speed of the fan 54, thereby regulating the rate at which heat is drawn from the chamber 26 for delivery to the rooms. In order to compensate for the varying temperature of the water stored in tank 30', which from time to time will range between I40 and 200 F., a tempering valve 66 may be employed to provide domestic hot water at one specified temperature, perhaps F. Such a valve contains a thermal sensor which regulates the mixing ratio of hot water and cold water input to obtain a constant temperature output.
It would be apparent to one having ordinary skill in the art that a suitable air filtration system could be provided within air return 52. In like manner. a humidifier could be provided within air supply duct 56. Additionally, it can be readily appreciated that the theoretical system of FIG. 2 could easily serve as thermal transfer means for a centralized air conditioning unit, utilizing the absorption refrigeration system aforementioned.
While there have been herein shown and described the preferred embodiments of the present invention. it will be understood that the invention may be embodied otherwise than is herein specifically illustrated or described and that in the illustrated embodiments certain changes in the detail of construction and in the form and arrangement of parts may be made without departing from the underlying idea or principles of this invention within the scope of the appended claims.
Having thus described our invention. what we claim as new, useful and non-obvious and accordingly secure by Letters Patent of the United States is:
l. A heat transfer system, comprising:
a. a heat source;
b. a plurality of heat pipes:
c. a thermal transformer thermally linked to both said heat pipes and said heat source. said transformer comprising:
i. a container,
ii. a working fluid and its vapor, said fluid and said vapor being essentially in equilibrium,
iii. evaporating surfaces depending from the internal surfaces of said transformer that are wetted by said working fluid and that are proximate to said heat source, and
iv. condensing surfaces depending from the exterior of those areas of said heat pipes that are in thermal contact with said transformer; and
d. a first chamber containing a medium with defined heat transfer characteristics, said chamber thermally coupled to said heat pipes,
whereby a uniform heat transfer from said heat source to said medium is obtained.
2. The system as recited in claim 1 in which said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
3. The system as recited in claim 1 in which said heat source comprises an electric heating element disposed externally proximate said transformer.
4. The system as recited in claim 2 in which said transformer is sealed while under a partial vacuum, said vacuum being measured exclusively of partial pressures contributed by said working fluid.
5. The system as recited in claim 1 in which said system further comprises: a second chamber containing a second medium with defined heat transfer characteristics, said second chamber being thermally connected to said first chamber by said heat pipe.
6. The system as recited in claim 1 in which said system further comprises:
a. an ancillary heat pipe;
b. a second chamber containing a second medium with defined thermodynamic properties, said second medium thermally connected to said first chamber by said ancillary heat pipe.
7. The system as defined in claim 5 in which said second medium may reside at a lower temperature than said first medium, thus creating a temperature gradient between said first and second chambers, thereby causing a heat transfer through said heat pipe between said chambers, said heat transfer occurring regardless of the degree of activity of said heat source.
8. The system as recited in claim 7 in which heat removed from said first chamber may be removed by either sensible or latent heat transfer.
9. The system as recited in claim 8 in which said system further includes:
a. a heat sensor disposed in one of said chambers; and
b. means for heat source control, associated with said sensor.
l0. The system as recited in claim 9 in which said first medium comprises water and said second medium comprises air.
11. The system as recited in claim 7 in which said heat pipe comprises a plurality of heat pipes, each of said heat pipes being disposed in a vertical plane that does not intersect the vertical plane of any other of said heat pipes.
12. The system as recited in claim 7 in which said heat source comprises: an exothermic chemical heat source.
13. The system as recited in claim 12 in which said system further comprises: a flue structure peripherally surrounding said thermal transformer and said heat source.
14. The system as recited in claim ll in which said condensing surface of said heat pipes comprises a multiplicity of fins, projecting radially from said heat pipes.
15. The system as recited in claim It) in which the working fluid of the transformer is water and the working fluid of said heat pipe is also water.
16. The system as recited in claim 10 in which the working fluid of said transformer is different from the working fluid of said heat pipe.
17. A heat transfer system, comprising:
a. a heat source;
b. a heat pipe having a first end and a second end;
c. a thermal transformer thermally linked to both said heat pipe and said heat source, said thermal transformer comprising:
i. a container,
ii. a working fluid and its vapor, said fluid and said vapor being essentially in equilibrium,
iii. evaporating surfaces depending from the internal surfaces of said transformer that are wetted by said working fluid and that are proximate to said heat source, and
iv. condensing surfaces depending from the exterior of those areas of said heat pipe that are in thermal contact with said transformer;
d. a first chamber containing a first medium with defined heat transfer characteristics and residing at a first temperature, said first chamber thermally coupled to said first end of said heat pipe; and
e. a second chamber containing a second medium with defined heat transfer characteristics and residing at a second temperature, said second chamber chamber thermally coupled to said second end of said heat pipe,
whereby both a first and a second heat transfer from said heat source to said first and second media respectively are obtained, said first and second heat transfers being a function of the respective thermal gradient between said heat source and each of said respective media, wherein each of said heat transfers is proportional to its respective thermal gradient.
IS. The system as recited in claim 17 is which said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
19. The system as recited in claim 17 in which heat source comprises an electric heating element disposed externally proximate said transformer.
20. The system as recited in claim 18 in which said transformer is sealed while under a partial vacuum, said vacuum being measured exclusively of partial pressures contributed by said working fluid.
21. The system as recited in claim 20 in which said heat pipe comprises a plurality of heat pipes.
22. The system as defined in claim 17 in which said second medium may reside at a lower temperature than said first medium. thus creating a temperature gradient between said first and second chambers. thereby causing a heat transfer thru said heat pipe between said chambers. said heat transfer occurring regardless of the degree of activity of said heat source.
23. The system as recited in claim 22 in which heat removed from said first chamber may be removed by either sensible or latent heat transfer.
24. The system as recited in claim 23 in which said system further includes:
a. a heat sensor disposed in one of said chambers; and
b. means for heat source control. associated with said sensor.
25. The system as recited in claim 24 in which said first medium comprises water and said second medium comprises air.
26. The system as recited in claim 22 in which said heat pipe comprises a plurality of heat pipes, each of said heat pipes being disposed in a vertical plane that does not intersect the vertical plane of any other of said heat pipes.
27. The system as recited in claim 22 in which said heat source comprises: an exothermic chemical heat source.
28. The system as recited in'claim 27 in which said system further comprises: a flue structure peripherally surrounding said thermal transformer and said heat source.
29. The system as recited in claim 26 in which said condensing surface of said heat pipes comprises a multiplicity 0f fins, projecting radially from said heat pipes.
30. The system as recited in claim 25 in which the working fluid of the transformer is water and the working fluid of said heat pipe is also water.
31. The system as recited in claim 25 in which the working fluid of said transformer is different from the working fluid of said heat pipe.

Claims (31)

1. A heat transfer system, comprising: a. a heat source; b. a plurality of heat pipes: c. a thermal transformer thermally linked to both said heat pipes and said heat source, said transformer comprising: i. a container, ii. a working fluid and its vapor, said fluid and said vapor being essentially in equilibrium, iii. evaporating surfaces depending from the internal surfaces of said transformer that are wetted by said working fluid and that are proximate to said heat source, and iv. condensing surfaces depending from the exterior of those areas of said heat pipes that are in thermal contact with said transformer; and d. a first chamber containing a medium with defined heat transfer characteristics, said chamber thermally coupled to said heat pipes, whereby a uniform heat transfer from said heat source to said medium is obtained.
2. The system as recited in claim 1 in which said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
3. The system as recited in claim 1 in which said heat source comprises an electric heating element disposed externally proximate said transformer.
4. The system as recited in claim 2 in which said transformer is sealed while under a partial vacuum, said vacuum being measured exclusively of partial pressures contributed by said working fluid.
5. The system as recited in claim 1 in which said system further comprises: a second chamber containing a second medium with defined heat transfer characteristics, said second chamber being thermally connected to said first chamber by said heat pipe.
6. The system as recited in claim 1 in which said system further comprises: a. an ancillary heat pipe; b. a second chamber containing a second medium with defined thermodynamic properties, said second medium thermally connected to said first chamber by said ancillary heat pipe.
7. The system as defined in claim 5 in which said second medium may reside at a lower temperature than said first medium, thus creating a temperature gradient between said first and second chambers, thereby causing a heat transfer through said heat pipe between said chambers, said heat transfer occurring regardless of the degree of activity of said heat source.
8. The system as recited in claim 7 in which heat removed from said first chamber may be removed by either sensible or latent heat transfer.
9. The system as recited in claim 8 in which said system further incLudes: a. a heat sensor disposed in one of said chambers; and b. means for heat source control, associated with said sensor.
10. The system as recited in claim 9 in which said first medium comprises water and said second medium comprises air.
11. The system as recited in claim 7 in which said heat pipe comprises a plurality of heat pipes, each of said heat pipes being disposed in a vertical plane that does not intersect the vertical plane of any other of said heat pipes.
12. The system as recited in claim 7 in which said heat source comprises: an exothermic chemical heat source.
13. The system as recited in claim 12 in which said system further comprises: a flue structure peripherally surrounding said thermal transformer and said heat source.
14. The system as recited in claim 11 in which said condensing surface of said heat pipes comprises a multiplicity of fins, projecting radially from said heat pipes.
15. The system as recited in claim 10 in which the working fluid of the transformer is water and the working fluid of said heat pipe is also water.
16. The system as recited in claim 10 in which the working fluid of said transformer is different from the working fluid of said heat pipe.
17. A heat transfer system, comprising: a. a heat source; b. a heat pipe having a first end and a second end; c. a thermal transformer thermally linked to both said heat pipe and said heat source, said thermal transformer comprising: i. a container, ii. a working fluid and its vapor, said fluid and said vapor being essentially in equilibrium, iii. evaporating surfaces depending from the internal surfaces of said transformer that are wetted by said working fluid and that are proximate to said heat source, and iv. condensing surfaces depending from the exterior of those areas of said heat pipe that are in thermal contact with said transformer; d. a first chamber containing a first medium with defined heat transfer characteristics and residing at a first temperature, said first chamber thermally coupled to said first end of said heat pipe; and e. a second chamber containing a second medium with defined heat transfer characteristics and residing at a second temperature, said second chamber chamber thermally coupled to said second end of said heat pipe, whereby both a first and a second heat transfer from said heat source to said first and second media respectively are obtained, said first and second heat transfers being a function of the respective thermal gradient between said heat source and each of said respective media, wherein each of said heat transfers is proportional to its respective thermal gradient.
18. The system as recited in claim 17 is which said transformer further comprises: a wick structure affixed to the interior surface of said transformer and in contact with said evaporating surfaces.
19. The system as recited in claim 17 in which heat source comprises an electric heating element disposed externally proximate said transformer.
20. The system as recited in claim 18 in which said transformer is sealed while under a partial vacuum, said vacuum being measured exclusively of partial pressures contributed by said working fluid.
21. The system as recited in claim 20 in which said heat pipe comprises a plurality of heat pipes.
22. The system as defined in claim 17 in which said second medium may reside at a lower temperature than said first medium, thus creating a temperature gradient between said first and second chambers, thereby causing a heat transfer thru said heat pipe between said chambers, said heat transfer occurring regardless of the degree of activity of said heat source.
23. The system as recited in claim 22 in which heat removed from said first chamber may be removed by either sensible or latent heat transfer.
24. The system as recited in claim 23 in which said system further includes: a. a heat sensor disposed in one of said chambers; and b. meAns for heat source control, associated with said sensor.
25. The system as recited in claim 24 in which said first medium comprises water and said second medium comprises air.
26. The system as recited in claim 22 in which said heat pipe comprises a plurality of heat pipes, each of said heat pipes being disposed in a vertical plane that does not intersect the vertical plane of any other of said heat pipes.
27. The system as recited in claim 22 in which said heat source comprises: an exothermic chemical heat source.
28. The system as recited in claim 27 in which said system further comprises: a flue structure peripherally surrounding said thermal transformer and said heat source.
29. The system as recited in claim 26 in which said condensing surface of said heat pipes comprises a multiplicity of fins, projecting radially from said heat pipes.
30. The system as recited in claim 25 in which the working fluid of the transformer is water and the working fluid of said heat pipe is also water.
31. The system as recited in claim 25 in which the working fluid of said transformer is different from the working fluid of said heat pipe.
US366193A 1973-06-01 1973-06-01 Heat transfer system Expired - Lifetime US3880230A (en)

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US366193A US3880230A (en) 1973-06-01 1973-06-01 Heat transfer system
CA186,008A CA982533A (en) 1973-06-01 1973-11-16 Heat transfer system
JP49014622A JPS5016154A (en) 1973-06-01 1974-02-06
FR7415331A FR2231929B1 (en) 1973-06-01 1974-05-03
DE2425745A DE2425745C3 (en) 1973-06-01 1974-05-28 Device for heat transfer
US05/478,982 US3994336A (en) 1973-06-01 1974-06-13 Transformer for heat pipes

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US20070240851A1 (en) * 2006-04-14 2007-10-18 Foxconn Technology Co., Ltd. Heat pipe
US9404392B2 (en) 2012-12-21 2016-08-02 Elwha Llc Heat engine system
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US2581347A (en) * 1943-07-09 1952-01-08 Electrolux Ab Absorption refrigeration apparatus and heating arrangement therefor
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US4037786A (en) * 1975-08-15 1977-07-26 International Telephone And Telegraph Corporation Energy recovery and storage system
US4582121A (en) * 1977-06-09 1986-04-15 Casey Charles B Apparatus for and method of heat transfer
US20050109057A1 (en) * 2003-11-25 2005-05-26 Twinbird Corporation Thermosiphon
EP1536191A3 (en) * 2003-11-25 2006-09-27 Twinbird Corporation Thermosiphon
US7234319B2 (en) 2003-11-25 2007-06-26 Twinbird Corporation Thermosiphon
US20050126761A1 (en) * 2003-12-10 2005-06-16 Je-Young Chang Heat pipe including enhanced nucleate boiling surface
US6990816B1 (en) * 2004-12-22 2006-01-31 Advanced Cooling Technologies, Inc. Hybrid capillary cooling apparatus
US20070240851A1 (en) * 2006-04-14 2007-10-18 Foxconn Technology Co., Ltd. Heat pipe
US9404392B2 (en) 2012-12-21 2016-08-02 Elwha Llc Heat engine system
US9752832B2 (en) 2012-12-21 2017-09-05 Elwha Llc Heat pipe
US10358945B2 (en) 2012-12-21 2019-07-23 Elwha Llc Heat engine system

Also Published As

Publication number Publication date
JPS5016154A (en) 1975-02-20
DE2425745B2 (en) 1978-09-28
CA982533A (en) 1976-01-27
FR2231929B1 (en) 1976-12-17
DE2425745C3 (en) 1979-05-23
DE2425745A1 (en) 1974-12-19
FR2231929A1 (en) 1974-12-27

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