CA1040025A - Heat transfer structure - Google Patents
Heat transfer structureInfo
- Publication number
- CA1040025A CA1040025A CA038,832A CA38832A CA1040025A CA 1040025 A CA1040025 A CA 1040025A CA 38832 A CA38832 A CA 38832A CA 1040025 A CA1040025 A CA 1040025A
- Authority
- CA
- Canada
- Prior art keywords
- matrix
- medium
- heat exchange
- structure according
- passageway
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F22—STEAM GENERATION
- F22B—METHODS OF STEAM GENERATION; STEAM BOILERS
- F22B27/00—Instantaneous or flash steam boilers
- F22B27/14—Instantaneous or flash steam boilers built-up from heat-exchange elements arranged within a confined chamber having heat-retaining walls
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/10—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
- F24H1/12—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium
- F24H1/14—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium by tubes, e.g. bent in serpentine form
- F24H1/145—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium by tubes, e.g. bent in serpentine form using fluid fuel
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H1/00—Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters
- F24H1/10—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium
- F24H1/12—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium
- F24H1/14—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium by tubes, e.g. bent in serpentine form
- F24H1/16—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium by tubes, e.g. bent in serpentine form helically or spirally coiled
- F24H1/165—Continuous-flow heaters, i.e. heaters in which heat is generated only while the water is flowing, e.g. with direct contact of the water with the heating medium in which the water is kept separate from the heating medium by tubes, e.g. bent in serpentine form helically or spirally coiled using fluid fuel
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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
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/003—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by using permeable mass, perforated or porous materials
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J19/00—Details of vacuum tubes of the types covered by group H01J21/00
- H01J19/28—Non-electron-emitting electrodes; Screens
- H01J19/32—Anodes
- H01J19/36—Cooling of anodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/40—Mountings or securing means for detachable cooling or heating arrangements ; fixed by friction, plugs or springs
- H01L23/4006—Mountings or securing means for detachable cooling or heating arrangements ; fixed by friction, plugs or springs with bolts or screws
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
- H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K7/00—Constructional details common to different types of electric apparatus
- H05K7/20—Modifications to facilitate cooling, ventilating, or heating
- H05K7/2089—Modifications to facilitate cooling, ventilating, or heating for power electronics, e.g. for inverters for controlling motor
- H05K7/209—Heat transfer by conduction from internal heat source to heat radiating structure
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2893/00—Discharge tubes and lamps
- H01J2893/0001—Electrodes and electrode systems suitable for discharge tubes or lamps
- H01J2893/0012—Constructional arrangements
- H01J2893/0027—Mitigation of temperature effects
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/34—Arrangements for cooling, heating, ventilating or temperature compensation ; Temperature sensing arrangements
- H01L23/40—Mountings or securing means for detachable cooling or heating arrangements ; fixed by friction, plugs or springs
- H01L23/4006—Mountings or securing means for detachable cooling or heating arrangements ; fixed by friction, plugs or springs with bolts or screws
- H01L2023/4018—Mountings or securing means for detachable cooling or heating arrangements ; fixed by friction, plugs or springs with bolts or screws characterised by the type of device to be heated or cooled
- H01L2023/4025—Base discrete devices, e.g. presspack, disc-type transistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Power Engineering (AREA)
- Combustion & Propulsion (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Dispersion Chemistry (AREA)
- Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
- Laminated Bodies (AREA)
- Gas Burners (AREA)
- Details Of Fluid Heaters (AREA)
Abstract
Abstract of the Disclosure Disclosed is a heat exchange structure for transferring heat between first and second fluid media through a thermally conductive rigid structure which incorporates a passageway for the first medium and a plurality of flow paths for the second medium. The paths are defined between a plurality of layers of bodies which are bonded together and to the portions of the structure forming the passageway in regions of contact therewith forming a matrix and whose surfaces, which form the elemental surface areas of the flow paths, are predominantly convexly curved in all directions. The average length of the flow paths is not greater than 15 times the average radius of curvature of the elemental surface areas.
Description
i~
' ~.~40()Z5 Background o the Invention The eficient transfer of heat as well as the eficient and economical conversion of thermal energy between flowing fluids and media to be heated or cooled is highly desirous in the present day art. The areas of intsrest reside in the home, for example, in cooking and heating, and in industry in numerous industrial processes such as condensation, distillation and heating. In the heat transfer art the completeness of extraction of thermal energy between a heated flowing 1uid and another medium is the parameter of primary concern. In normal fuel burners, for example, with limited heat transfer area the exhaus~ temperatures which may be a few hundred degrees indicate that a considerable amount of avail-'~ _ 1 _ ~ '' -`-;
~(~4t~5 able heat in the fuel is not utilized and is transported through the chimney flue. Efficiencies of between 50 percent to 60 percent are, therefore, quite conventional in present day thermal energy conversion devices.
IncrPasing the transfer area between the flowing fluid medium to be heated in applicabla devices through baffles,-plates, tinsel or other obstructions has not met with marked success in improvement of heat transfer efficiencies. An expression often uti-lized in the art to describe the heat transfer characteristics is "power density" which denotes the thermal energy per unit of time fl~wing through a unit of area of a bo~y to be heated. Prior art devices have normally observed power densities in the order of 100 watts per square inch of transfer area. This indicates that with the numerous high thermal energy sources available such as, for example, a direct flame having a 7 kilowatt output capability higher efficiencies will be realized if the power density characteristic of the transfer structure can be suitably enhanced.
New and novel structures to achieve much higher efficiencies with power densities 10 to 100 times that normally achieved in the transfer of thermal energy will be described in accordance with the teachings of the present invention.
Summary of the Invention A compact structure for rapid transfer of thermal energy and vast improvement in the power density factor is provided by the arrangement of a plurality of thermal conducting bodies in a bonded porous barrier matrix. The interstices between the contiguous surfaces of the bodies in the matrix define a tortuous path for a fluid heating or cooling medium. A heat transfer inter-Q(~ZS
face surface arranged adjacent to the barrier matrix provides for the passage of a second medium at a higher or lower temperature differential relative to the fluid medium within the barrier matrix structure. The porosity and density of the barrier matrix composed of individual thermally conductive members is of a predetermined design parameter to provide for efficient heat transfer between the media. In accordance with this invention, an optimum requirement for the depth and porosity of the barrier matrix is that the average size of the thermal conducting bodies be substantially the size which will produce an optically dense path in substantially the shortest distance along a passageway or restricted path for a flowing fluid, For the purposes of the description of the invention the term "optically dense" is defined as relating to the packing of the individual thermal conductive bodies in such a manner that a beam of light directed through the resultant structure will not be directly visiblo but small traces of light may be noted in the interstices between the individual bodies because of in~ernal reflections and light scatter. The heat transfer barrier matrix may be provided by joining together the thermally conductive members through conventional brazing, sintering or soldering techniques by coating the individual members with suitable materials having characteristics for such metallurgical processes.
Another term useful in the understanding of the present invention and description of the parameters of the individual thermal conducting bodies and maximum heat flow paths is the "characteristic dimension.ll This term shall be interpreted to denote the distance between adjacent transfer interface boundaries of a passageway occupied by the optically dense barrier matrix through which one of the fluid media flows. In a circular configuration with an internally contained matrix structure the characteristic ~09~ 25 dimension will be the diameter of the passageway containing the fluid medium means. In the flat or planar configuration having spaced parallel thermally conductive interface boundaries with the barrier matrix structure disposed therebetween the term shall denote the distance batween the parallel boundary means. In configurations providing fluid medium circulating means embedded in an external barrier matrix configuration the term shall define the distance between adjacent interface conduit means. If circular conduits are involved then the distance may be derived by averaging the separation dimensions at preselected points.
Numerous embodiments of the present invention will be described including coiled fluid passage means embedded within an optically dense barrier matrix. Such a structure will provide an efficient domestic hot water source and may be advantageously disposed at any desired utilization point. Another embodiment of the invention incorporates the disposition o thermal conductive bodies within as well as surrounding the medium con-ducting path to accommodate heat power densities as high as 1OJOOO watts per s~uare inch Eor applications such as, for example, boilers for furnaces.
l'he high efficiencies realized with the disclosed embodiments will result in substantial reductions in space and cost of heat transfer modules.
Thus, in accordance with the invention, there is provided a heat exchange structure for transferring heat between first and second fluid media through a thermally conductive rigid structure which incorpor-ates a passageway for the first medium and a plurality of flow paths for the second medium~ which paths are defined between a plurality of layers of ; bodies which are bonded together and to the portions of said structure forming said passageway in regions of contact therewith forming a matrix and whose surfaces, which form the elemental surface areas of the flow paths, are predominantly convexly curved in all directions, wherein the average length of the flow paths is not greater than 15 times the average radius of curvature of the said elemental surface areas.
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~4~U;Z5 Brief Description of the Drawings The invention, as well as the specific illustrative embodiments, will now be described, reference being directed to the accompanying draw-ings in which:
Figure 1 is a vertical cross-sectional view of an illustrative embodiment of the invention for heating of a circulating liquid by an external matrix structure;
- 4a -3L~41~(~z5 Figure 2 is an enlarged fragmentary view of a portion of the external matrix included within the line 2-2 in Figure l;
Figure 3 is a sectional view taken along the line 3-3 in Figure l viewed in the direction of the arrows;
Figure 4 is a diagrammatic representation of the principal optimum parameters of the illustrative embodiment;
Figure 5 is a diagrammatic representation of a flat planar heat transfer configuration;
Figure 6 is a diagrammatic representation of the embedded external barrier matrix structure illustrative of one of the conceptual configurations of the present invention;
Figure 7 is a schematic representation of a complete system utilizing the illustrative heat transfer module illustrated in Figures 1 through 3 inclusive;
Figure 8 is a vertical sectional view of an alternative embodi-ment of the present invention;
Figure 9 is a horizontal sectional view taken along the line 9-9 in Figure 8;
Figure 10 is a vertical sectional view of another alternative embodiment o the invention to provide high power density parameters;
Figure 11 is a vertical sectional view along the line 11-11 in Figure 10; and Figure 12 is an exploded fragmentary partially sectioned view illustrative of an alternative embodiment of the invention.
Descri tion of the Preferred Embodiment P . _ In the drawings, Figures 1, 2 and 3 illustrate a preferred embodiment of the invention. Before proceeding to the detailed description, however, it will be of assistance to refer to 1()41~(~ZS
Figures 4, 5 and 6 and a description of the important conceptual aspects of the invention.
A heat transfer arrangement which provides for a high thermal transfer rate utilizing a structure ~o provide optimum power density along a heat flow path is illustrated in Figure 4.
Thermally conductive bodies are metallurgically bonded along contiguous surfaces ~o define an optically dense barrier matrix 11 along a fluid flow path. The interstices between the bodies define a tortuous heat transfer path. Spherical members, such as shot or ball bearings, have been shown although similar results are attainable with other similarly oriented members the configuration and dimensions o which meet the critical parameters required by the invention. Suitable thermally conductive materials include copper, brass, stainlass steel, carbon steel, aluminum, as well as any of the plastic materials embedded with metallic particles. Each of the ferrous or copper body members may be coated with a copper-silver eutectic solder and the overall matrix structure may be conglomerated by any of the well known processes including brazing, sintering or welding. A dip brazing technique is required for aluminum conductive members.
Achievement of the maximum average size for the body members to secure an optically dense matrix in the shortest distance possible along the direction of fluid flow is one of the design criteria to be followed in the practice of the invention. A flowing fluid along a path indicated by arrow 13 will encounter the optically dense structure which is joined to a surface of a conducting boundary interface 12. Through the provision of a number of body members 10 arranged to provide tortuousheat transfer paths in the optically dense barrier matrix the total overall efficiency of the heat trans-fer device is enhanced. The path o the thermal energy flow from the :~40(~Z5 flowing fluid through the matrix 11 and interface surace 12 is indicated by the arrow 1~ to result in transfer to the media contacting the opposing sur-face 15.
Another criteria required for the provision of an efficient heat transfer structure in the shortest distance possible along the heat flow path concerns the number of bonded joints or junctions in any direction from the point of thermal contact along a heat path to the nearest adjacent conducting interface. Referring to Figure 5, a~matrix structure 16 is shown disposed between spaced interface boundary surfaces 17 and 18. Such surfaces may be provided between the walls within a conduit or between the outer walls of ; spaced conduits as will hereinafter be described. The fluid flow path is indicated by the arrow 19. It has been discovered that optimum results will be obtained with an optically dense arrangement when the number of contiguous bonded joints in a desired heatli path direction from the point of contact to the nearest ad~acent interface surface is in the order of two such brazed joints. The barrier matrix structure disclosed herein is of the internally mounted configuration and may be practicedin circula~ or rectangular conduits as well as between flat planar plates.
The remaining c~iteria hereinbefore defined is the characteristic transverse dimension shown in Figure 5, and designated by the arrow C.D. as the distance betweon the parallel boundary surfaces 17 and 18. To achieve the highest heat transfer rates with an optically dense barrier structure the heat path to the nearest boundary interface surface for aflowing fluid directed along path 19 may be depicted by perpendicularly directed arrows 20 and 21. The maximum length of the heat path through the matrix from the fluid to the nearest boundary interface then may be defined as one-half of the characteristic transverse dimension of the device. For barrier structures employing dlscrete bodies the present invention discloses that the average size of each of the '~1 bodies shall preferably be approximately one-third of the characteris-tic dimension of the device. Bodies of substantially larger dimen-sions, for example, above one-half of the characteristic dimension, ~ould not collectively define a sufficiently optically dense arrange-ment. In fact, such a device would be highly inefficient in the transfer of incremental quanta of thermal energy. At the other extreme of the range, thermally conductive bodies of smaller diameters below one-sixth of the characteristic dimension violate the number of brazed joints requirement and thereby lower the thermal conductivity efficiency of the heat transfer device.
Figure 6 illustrates an embodiment of the invention wherein the spaced conduit means for directing the flow of a fluid are embedded in the barrier matrix and a second flowing fluid is directed in the region between the conduit means as indicated by arrow 22.
This configuration is referred to as the external type and again the design criteria of the number of bonded joints as well as optical density of the matrlx are applicable. A circular conduit 23 which may comprise a linear array of parallel members or a helical coil is encased in the barrier matrix 24 of thermally conductive bodies fabricated in accordance with the invention.
The characteristic dimension of this configuration is calculated between the conduit wall surfaces and is derived by averaging the dimension A as well as the dimension B which represents the furthermost spacing between the conduit means. Thermal energy directed along path 22 will traverse heat paths indicated by arrows 25 and 26 to the adjacent conduit walls. Again, as in the example shown in Figure 5, the heat path maximum is desirably one-half the characteristic dimension or average distance between the spaced conduit walls. The number of brazed joints are in the order of two from point of impact and the average size of the bodies will be between one-half to one-sixth of the characteristic dimension for the requisite optical density. In such cases with the one-hal~ body dimension an average of one brazed joint will inherently result and in the case of the one-sixth dimension an average of about three brazed ~oints will inherently resul~.
The high heat transfer rate or increased power density achieved by the invention is believed to be attributable to the large number of surfaces provided by the conductive area of each of the matrix body members, turbulent fluid flow and the very short heat flow path through the matrix from the fluid to the interface surface. Relatively high power densities are attainable in embodiments of the invention to be hereinafter described and may be as high as 10,000 watts per square inch of the area of the face of the matrix body initially impinged by the flame. Compared with embodiments of conventional prior art structures capable of handling power densities of only 100 watts per area per unit o~ time it is apparent that an improvement of several ~ orders of magnitude have resulted. A useful equation in the determination ; o~ the design criteria incorporating the teachings of the invention are as follows:
(temp. drop)(conductivity of material) (1) Heat, path (L) = heat flux The term "heat flux" refers to input thermal enerey and may be expressed in terms of British thermal units per hour per square feet of wall area of the interface boundary through which the heat is transferred. Since the power density on the face of the matrix is transferred to the wall area, the heat flux will be approximately one-tenth of the above 10,000 watts or 1,000 watts.
Thermal conductivity of the material is a constant value and is readily determined from tables for that purpose. This term indicates the quantity ; of heat that will flow across a unit area of the body heated ~f the temper-ature gradient is unity. As stated previously, the heat path then re-presents one-half of the characteristic dimension. The matrix body member dlmensions can then be readily computed rrom this value of characteristic dimension. The applica~ion of this equation will be demonstrated hereinafter in relation to one of the described embodiments.
In Figures 1, 2 and 3 a highly efficient and practical embodiment of the present invention is illustrated and will now be described. ~elical conduit 30 is embedded in and surrounded by an external sinte~ed barrier matrix 31. The matrix 31 is composed of discrete thermally conductive bodies to provide for the optical density in accordance with the teachings of the invention as have hereinbefore been enumerated. The thermal conductivity, pressure drop limits and power density will determine the pitch, diameter and overall length of the conduit to arrive at the maximum allow-able heat path and this in turn will deteTmine the characteristic dimensions, The matrix design criteria are then determined from the characteristic dimension value. An inlet 32 and outlet 33 are, respectively, connected to the water source and egress means for the utilization of the fluid medium. The embedding of the conduit in the barrier matrix can be achieved by positioning the helical conduit 30 within a cylindrical space defined by two con-centrically disposed tubular jig members of a material which will not bond to the body members whose dimensions are related to the characteristic dimension value. The jig members have different diameters and the circular space between these members may be filled with the individual body members. Shaking and vibrating of the over-all assembly will provide for the desired array of the bodies around each of the conduit turns. The entire assembly is then metallurgically treated at the requisite temperature and the jig members may be separated. The combined external barrier matrix structure and conduit is then assembled in the embodiment and a central combustion chamber 38 is defined by the disclosed heat transfer matrix.
1~4~ZS
Typically, a burner plate member 34 may be provided with a plurality of passageways 35 for the admittance of an air-gas mixture under pressure from a source coupled to conduit 36 and fitting 37 into the combustion chamber 38. Angularly and laterally disposed within the burner plate member 34 is an ignition means 40 of any well known construction such as a spark plug to provide the necessary ignition of the gaseous fuel mixture. Outer wall member 41 surrounds the heat transfer struc~ure and a flue 42 for the passage of the exhaust gases extends ~o a conventional chimney (not shown). Top plate member 43 is suitably secured to the heat transfer structure and conduit such as by nut and bolt means ~4, part of which may also be embedded in the matrix.
In an exemplary working embodiment a heat transfer unit as described in Figures 1 through 3 inclusive having dimensions of about five inches in diameter and about five inches in length was utilized to provide a continuous hot water flow of approximately three gallons per minute. The burner driving the heat transfer unit and all the electrical controls including a thermostat, air filter and safety regulating devices were incorporated into a structure having a height of about six inches, a width of about twelve inches and an overall length of about eighteen inches.
Such a heat transfer module can replace conventional present day hot water heaters of the storage tank variety having diameters of approximately two feet and heights of approximately six feet.
The new improved structure can be very conveniently mounted adjacent to the final utilization point. In view of the exceeding-ly low cost many such devices can also be incorporated with resul-tant savings in cost of piping and plumbing necessary with present day centralized domestic hot water heating systems.
Referring now to Figure 7, the embodiment of the invention ~4~5 shown in Figures 1-3 inclusive together with the appurtenant s~ructures, is collectively referred to as a heat transfer module designated by the numeral 50. An air blower 51 is coupled through the fitting 37 to feed the air and gas mixture into combustion chamber 38. A gas from source 53 which may be any commercially available natural or tank type, is fed through a solenoid control valve 54 and regulator 55 to the inlet 52 in blower 51. Any small size blower of the inexpensive variety should suffice for most applications. The vent 42 extending laterally from the heat transfer module 50 will provide for the egress of the combustion gases to a convenient outlet Due to the efficiency of the hea~
transfer and the fact that the exhaust te~perature is exceedingly low a small vent opening in a wall may be used similar to the type employed in home clothes dryers. No natural draft type chimney is required, which also results in savings in construction costs. The water supply is indicated by numeral 56 and the heated water medium is fed through line 57 to the outlet tap 58 for instant usage A
temperature and pressure relief valve 59 may be disposed in line 57 It i5 thus noted that large storage tanks or boilers utilized in present day hot water generation sources are completely elimina-ted. A compact and unique source is thus disclosed which may be readily installed directly in the area where the use is intended, for example, the bathroom or kitchen.
Associated wiring for the control of the blower as well as the thermostat and ignition controls together with the main solenoid valve for the gas source have not been specifically described since they are readily commercially available and normal techniques incor-porating such means will be followed.
In Figures 8 and 9 a linear array of fluid conduits 61 is embedded within barrier matrix 62 composed of thermally conductive - 12 _ zs bodies as have hereinbefore been described. Upper plate member 63 supports fluid inlet passage means 64 and is secured by fastening means 65 to screws 66 embedded in collar member 67, The optically dense matrix structure 62 surrounds the linear conduits 61 which are embedded therein, the ends of these conduits and the inlet 64 all communicating with a channel 68 in the inner side of collar member 67. A similar end arrangement is disposed at the opposite end of the matrix structure including a lower plate member 71 and adjacent collar member 70 and communicates with an inner channel 68a in collar member 70 with which the adjacent ends of conduits 61 also communicate. A fluid outlet means 72 is supported by the lower collar member 70. Plate member 71 further defines a plurality of passages 73 for a gas-air mixture fed into the device through conduit 74. The ignition means for the combustible fuel within the chamber 75 is furnished by spark plug member 76 supported by upper plate member 63.
Figures 10 and 11 are directed to an embodiment for very high power density applications, In such embodiments conduits 77 and 78 are disposed about a common axis. Outer conduit 77 is closed by conductive plate means 79 and 80 at opposing ends. Inlet member 81 provides for the ingress of a fluid medium and outlet member 82 provides for the egress of the medium in the vaporized or heated state. The inner conduit 78 is open at the ends for the flow of a heated medium such as the gases from a direct oxygen-gas flame along the inner passage 83 of this conduit, with the direction of flow being indicated by the arrow 84. An optically dense barrier matrix structure 85 comprises a plurality of thermally conductive spherical members joined together to define the thermal transfer paths in accordance with the teachings of the invention. The barrier structure 85 occupies a major portion of the cross-sectional :1~4~(~Z5 area o the conduit 78 and the characteristic dimension of this member will be the inner diameter of the circular conduit as designated by the arrow 86 and symbol C.D.
A similar barrier matrix 87 occupies the cross-sectional area of the outer conduit 77. With the internal barrier matrix structure 85 occupying only a portion of *he overall length of the passage 83 for concentration of the hsated medium, the heat trans-fer area between the medium in the respecti~e conduits will occur substan~ially in the region indicated by the bracket 88. This configuration then provides for high power density applications.
An example of the application of the previously enumerated equation (l) in the transfer of heat from an intense heat source may be noted in the high power density embodiment of Figures lO and 11, Utilizing a direct flame source we assume that a power density of lO,000 watts per square inch of flame area is obtained and yet silver brazed copper members may be employed. Additionally, it is assumed that a desired temperature drop of 100 degrees Fahrenheit is specified, Copper has a thermal conductivity value of about 200 BTU/hour/ft/F. In the final structure we assume that a lower conductivity will be realized due to the brazed joints and optical density of the thermal paths. A conductivity factor of 50 percent then will provide a reliable design factor. Utilizing the other known values the heat path ~L) is calculated as follows:
L = lO0 X 16 = 2 X lO 2 feet = 1/4 inch The characteristic dimension will then be twice the heat path value or l/2 inch. A thermally conductive body average size of between one-quarter and one-twelfth of an inch therefore is indicated for the required optimum optical density. A one-third value or one-sixth of an inch for thermal body size is preferred in most applica-tions ~a~o~s In Flgure 12 another embodiment is illustrated. A helical conduit having a plurality o~ turns 90 iB embedded within a matrix 91 of the external type. If we provide the proper design criteria for the matrix members surround-ing the conduit the interior passages thereof may be filled with other conduc-tive members which need not meet these same critical requirements. Hence, in applications where steam is generated and in condensation devices particles such as mesh, wires, shavings, cuttings and the like can be employed, as indi-cated collectively by numeral 92. Such a configuration for the obstructions within the conduit will provide for even ~ider application of the invention in industry As can be seen from any figure of the drawings, e.g. Fig. 1, the gas passage length through the sintered matrix o~ spheres 31 preferably does not substantially exceed seven l~yers of balls, or approximately 15 times the average radius of curvature of the passage surfaces, and the average radius of curvature of the spheres 31 is substantially less than the radius of curvature o~ the interior surface of condult 30.
The advantages of compactness and efficiency of the disclosed thermal transfer device ln the provision of vastly improved power densities through the optically dense matrix structure will now be apparent to those skllled in the art from thls description. The design criteria o~ the number o~ bonded ~oints along the heat path and the average size of the thermally conductive bodies in relation to the characteristic d~mension to provide the desired optical density have been carefully enumerated. The foregoing dis-cussion and exemplary application of the equation will also assist in the practice of the invention. In addition to the exemplary embodiments numerous other configurations will be evident for other applications. For example, the thermally conductive body members in contact with the outermost wall surfaces of circular conduiis shown in Figs. 1 and 8 may be eliminated, thereby exposing this portion of the boundary interface conduit walls. The heat transfer paths within the matrix between the spaced conduit members would still be defined in accordance with this invention by the thermally conductive bodies in the fluid flow path.
' ~.~40()Z5 Background o the Invention The eficient transfer of heat as well as the eficient and economical conversion of thermal energy between flowing fluids and media to be heated or cooled is highly desirous in the present day art. The areas of intsrest reside in the home, for example, in cooking and heating, and in industry in numerous industrial processes such as condensation, distillation and heating. In the heat transfer art the completeness of extraction of thermal energy between a heated flowing 1uid and another medium is the parameter of primary concern. In normal fuel burners, for example, with limited heat transfer area the exhaus~ temperatures which may be a few hundred degrees indicate that a considerable amount of avail-'~ _ 1 _ ~ '' -`-;
~(~4t~5 able heat in the fuel is not utilized and is transported through the chimney flue. Efficiencies of between 50 percent to 60 percent are, therefore, quite conventional in present day thermal energy conversion devices.
IncrPasing the transfer area between the flowing fluid medium to be heated in applicabla devices through baffles,-plates, tinsel or other obstructions has not met with marked success in improvement of heat transfer efficiencies. An expression often uti-lized in the art to describe the heat transfer characteristics is "power density" which denotes the thermal energy per unit of time fl~wing through a unit of area of a bo~y to be heated. Prior art devices have normally observed power densities in the order of 100 watts per square inch of transfer area. This indicates that with the numerous high thermal energy sources available such as, for example, a direct flame having a 7 kilowatt output capability higher efficiencies will be realized if the power density characteristic of the transfer structure can be suitably enhanced.
New and novel structures to achieve much higher efficiencies with power densities 10 to 100 times that normally achieved in the transfer of thermal energy will be described in accordance with the teachings of the present invention.
Summary of the Invention A compact structure for rapid transfer of thermal energy and vast improvement in the power density factor is provided by the arrangement of a plurality of thermal conducting bodies in a bonded porous barrier matrix. The interstices between the contiguous surfaces of the bodies in the matrix define a tortuous path for a fluid heating or cooling medium. A heat transfer inter-Q(~ZS
face surface arranged adjacent to the barrier matrix provides for the passage of a second medium at a higher or lower temperature differential relative to the fluid medium within the barrier matrix structure. The porosity and density of the barrier matrix composed of individual thermally conductive members is of a predetermined design parameter to provide for efficient heat transfer between the media. In accordance with this invention, an optimum requirement for the depth and porosity of the barrier matrix is that the average size of the thermal conducting bodies be substantially the size which will produce an optically dense path in substantially the shortest distance along a passageway or restricted path for a flowing fluid, For the purposes of the description of the invention the term "optically dense" is defined as relating to the packing of the individual thermal conductive bodies in such a manner that a beam of light directed through the resultant structure will not be directly visiblo but small traces of light may be noted in the interstices between the individual bodies because of in~ernal reflections and light scatter. The heat transfer barrier matrix may be provided by joining together the thermally conductive members through conventional brazing, sintering or soldering techniques by coating the individual members with suitable materials having characteristics for such metallurgical processes.
Another term useful in the understanding of the present invention and description of the parameters of the individual thermal conducting bodies and maximum heat flow paths is the "characteristic dimension.ll This term shall be interpreted to denote the distance between adjacent transfer interface boundaries of a passageway occupied by the optically dense barrier matrix through which one of the fluid media flows. In a circular configuration with an internally contained matrix structure the characteristic ~09~ 25 dimension will be the diameter of the passageway containing the fluid medium means. In the flat or planar configuration having spaced parallel thermally conductive interface boundaries with the barrier matrix structure disposed therebetween the term shall denote the distance batween the parallel boundary means. In configurations providing fluid medium circulating means embedded in an external barrier matrix configuration the term shall define the distance between adjacent interface conduit means. If circular conduits are involved then the distance may be derived by averaging the separation dimensions at preselected points.
Numerous embodiments of the present invention will be described including coiled fluid passage means embedded within an optically dense barrier matrix. Such a structure will provide an efficient domestic hot water source and may be advantageously disposed at any desired utilization point. Another embodiment of the invention incorporates the disposition o thermal conductive bodies within as well as surrounding the medium con-ducting path to accommodate heat power densities as high as 1OJOOO watts per s~uare inch Eor applications such as, for example, boilers for furnaces.
l'he high efficiencies realized with the disclosed embodiments will result in substantial reductions in space and cost of heat transfer modules.
Thus, in accordance with the invention, there is provided a heat exchange structure for transferring heat between first and second fluid media through a thermally conductive rigid structure which incorpor-ates a passageway for the first medium and a plurality of flow paths for the second medium~ which paths are defined between a plurality of layers of ; bodies which are bonded together and to the portions of said structure forming said passageway in regions of contact therewith forming a matrix and whose surfaces, which form the elemental surface areas of the flow paths, are predominantly convexly curved in all directions, wherein the average length of the flow paths is not greater than 15 times the average radius of curvature of the said elemental surface areas.
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.~
, ~
~4~U;Z5 Brief Description of the Drawings The invention, as well as the specific illustrative embodiments, will now be described, reference being directed to the accompanying draw-ings in which:
Figure 1 is a vertical cross-sectional view of an illustrative embodiment of the invention for heating of a circulating liquid by an external matrix structure;
- 4a -3L~41~(~z5 Figure 2 is an enlarged fragmentary view of a portion of the external matrix included within the line 2-2 in Figure l;
Figure 3 is a sectional view taken along the line 3-3 in Figure l viewed in the direction of the arrows;
Figure 4 is a diagrammatic representation of the principal optimum parameters of the illustrative embodiment;
Figure 5 is a diagrammatic representation of a flat planar heat transfer configuration;
Figure 6 is a diagrammatic representation of the embedded external barrier matrix structure illustrative of one of the conceptual configurations of the present invention;
Figure 7 is a schematic representation of a complete system utilizing the illustrative heat transfer module illustrated in Figures 1 through 3 inclusive;
Figure 8 is a vertical sectional view of an alternative embodi-ment of the present invention;
Figure 9 is a horizontal sectional view taken along the line 9-9 in Figure 8;
Figure 10 is a vertical sectional view of another alternative embodiment o the invention to provide high power density parameters;
Figure 11 is a vertical sectional view along the line 11-11 in Figure 10; and Figure 12 is an exploded fragmentary partially sectioned view illustrative of an alternative embodiment of the invention.
Descri tion of the Preferred Embodiment P . _ In the drawings, Figures 1, 2 and 3 illustrate a preferred embodiment of the invention. Before proceeding to the detailed description, however, it will be of assistance to refer to 1()41~(~ZS
Figures 4, 5 and 6 and a description of the important conceptual aspects of the invention.
A heat transfer arrangement which provides for a high thermal transfer rate utilizing a structure ~o provide optimum power density along a heat flow path is illustrated in Figure 4.
Thermally conductive bodies are metallurgically bonded along contiguous surfaces ~o define an optically dense barrier matrix 11 along a fluid flow path. The interstices between the bodies define a tortuous heat transfer path. Spherical members, such as shot or ball bearings, have been shown although similar results are attainable with other similarly oriented members the configuration and dimensions o which meet the critical parameters required by the invention. Suitable thermally conductive materials include copper, brass, stainlass steel, carbon steel, aluminum, as well as any of the plastic materials embedded with metallic particles. Each of the ferrous or copper body members may be coated with a copper-silver eutectic solder and the overall matrix structure may be conglomerated by any of the well known processes including brazing, sintering or welding. A dip brazing technique is required for aluminum conductive members.
Achievement of the maximum average size for the body members to secure an optically dense matrix in the shortest distance possible along the direction of fluid flow is one of the design criteria to be followed in the practice of the invention. A flowing fluid along a path indicated by arrow 13 will encounter the optically dense structure which is joined to a surface of a conducting boundary interface 12. Through the provision of a number of body members 10 arranged to provide tortuousheat transfer paths in the optically dense barrier matrix the total overall efficiency of the heat trans-fer device is enhanced. The path o the thermal energy flow from the :~40(~Z5 flowing fluid through the matrix 11 and interface surace 12 is indicated by the arrow 1~ to result in transfer to the media contacting the opposing sur-face 15.
Another criteria required for the provision of an efficient heat transfer structure in the shortest distance possible along the heat flow path concerns the number of bonded joints or junctions in any direction from the point of thermal contact along a heat path to the nearest adjacent conducting interface. Referring to Figure 5, a~matrix structure 16 is shown disposed between spaced interface boundary surfaces 17 and 18. Such surfaces may be provided between the walls within a conduit or between the outer walls of ; spaced conduits as will hereinafter be described. The fluid flow path is indicated by the arrow 19. It has been discovered that optimum results will be obtained with an optically dense arrangement when the number of contiguous bonded joints in a desired heatli path direction from the point of contact to the nearest ad~acent interface surface is in the order of two such brazed joints. The barrier matrix structure disclosed herein is of the internally mounted configuration and may be practicedin circula~ or rectangular conduits as well as between flat planar plates.
The remaining c~iteria hereinbefore defined is the characteristic transverse dimension shown in Figure 5, and designated by the arrow C.D. as the distance betweon the parallel boundary surfaces 17 and 18. To achieve the highest heat transfer rates with an optically dense barrier structure the heat path to the nearest boundary interface surface for aflowing fluid directed along path 19 may be depicted by perpendicularly directed arrows 20 and 21. The maximum length of the heat path through the matrix from the fluid to the nearest boundary interface then may be defined as one-half of the characteristic transverse dimension of the device. For barrier structures employing dlscrete bodies the present invention discloses that the average size of each of the '~1 bodies shall preferably be approximately one-third of the characteris-tic dimension of the device. Bodies of substantially larger dimen-sions, for example, above one-half of the characteristic dimension, ~ould not collectively define a sufficiently optically dense arrange-ment. In fact, such a device would be highly inefficient in the transfer of incremental quanta of thermal energy. At the other extreme of the range, thermally conductive bodies of smaller diameters below one-sixth of the characteristic dimension violate the number of brazed joints requirement and thereby lower the thermal conductivity efficiency of the heat transfer device.
Figure 6 illustrates an embodiment of the invention wherein the spaced conduit means for directing the flow of a fluid are embedded in the barrier matrix and a second flowing fluid is directed in the region between the conduit means as indicated by arrow 22.
This configuration is referred to as the external type and again the design criteria of the number of bonded joints as well as optical density of the matrlx are applicable. A circular conduit 23 which may comprise a linear array of parallel members or a helical coil is encased in the barrier matrix 24 of thermally conductive bodies fabricated in accordance with the invention.
The characteristic dimension of this configuration is calculated between the conduit wall surfaces and is derived by averaging the dimension A as well as the dimension B which represents the furthermost spacing between the conduit means. Thermal energy directed along path 22 will traverse heat paths indicated by arrows 25 and 26 to the adjacent conduit walls. Again, as in the example shown in Figure 5, the heat path maximum is desirably one-half the characteristic dimension or average distance between the spaced conduit walls. The number of brazed joints are in the order of two from point of impact and the average size of the bodies will be between one-half to one-sixth of the characteristic dimension for the requisite optical density. In such cases with the one-hal~ body dimension an average of one brazed joint will inherently result and in the case of the one-sixth dimension an average of about three brazed ~oints will inherently resul~.
The high heat transfer rate or increased power density achieved by the invention is believed to be attributable to the large number of surfaces provided by the conductive area of each of the matrix body members, turbulent fluid flow and the very short heat flow path through the matrix from the fluid to the interface surface. Relatively high power densities are attainable in embodiments of the invention to be hereinafter described and may be as high as 10,000 watts per square inch of the area of the face of the matrix body initially impinged by the flame. Compared with embodiments of conventional prior art structures capable of handling power densities of only 100 watts per area per unit o~ time it is apparent that an improvement of several ~ orders of magnitude have resulted. A useful equation in the determination ; o~ the design criteria incorporating the teachings of the invention are as follows:
(temp. drop)(conductivity of material) (1) Heat, path (L) = heat flux The term "heat flux" refers to input thermal enerey and may be expressed in terms of British thermal units per hour per square feet of wall area of the interface boundary through which the heat is transferred. Since the power density on the face of the matrix is transferred to the wall area, the heat flux will be approximately one-tenth of the above 10,000 watts or 1,000 watts.
Thermal conductivity of the material is a constant value and is readily determined from tables for that purpose. This term indicates the quantity ; of heat that will flow across a unit area of the body heated ~f the temper-ature gradient is unity. As stated previously, the heat path then re-presents one-half of the characteristic dimension. The matrix body member dlmensions can then be readily computed rrom this value of characteristic dimension. The applica~ion of this equation will be demonstrated hereinafter in relation to one of the described embodiments.
In Figures 1, 2 and 3 a highly efficient and practical embodiment of the present invention is illustrated and will now be described. ~elical conduit 30 is embedded in and surrounded by an external sinte~ed barrier matrix 31. The matrix 31 is composed of discrete thermally conductive bodies to provide for the optical density in accordance with the teachings of the invention as have hereinbefore been enumerated. The thermal conductivity, pressure drop limits and power density will determine the pitch, diameter and overall length of the conduit to arrive at the maximum allow-able heat path and this in turn will deteTmine the characteristic dimensions, The matrix design criteria are then determined from the characteristic dimension value. An inlet 32 and outlet 33 are, respectively, connected to the water source and egress means for the utilization of the fluid medium. The embedding of the conduit in the barrier matrix can be achieved by positioning the helical conduit 30 within a cylindrical space defined by two con-centrically disposed tubular jig members of a material which will not bond to the body members whose dimensions are related to the characteristic dimension value. The jig members have different diameters and the circular space between these members may be filled with the individual body members. Shaking and vibrating of the over-all assembly will provide for the desired array of the bodies around each of the conduit turns. The entire assembly is then metallurgically treated at the requisite temperature and the jig members may be separated. The combined external barrier matrix structure and conduit is then assembled in the embodiment and a central combustion chamber 38 is defined by the disclosed heat transfer matrix.
1~4~ZS
Typically, a burner plate member 34 may be provided with a plurality of passageways 35 for the admittance of an air-gas mixture under pressure from a source coupled to conduit 36 and fitting 37 into the combustion chamber 38. Angularly and laterally disposed within the burner plate member 34 is an ignition means 40 of any well known construction such as a spark plug to provide the necessary ignition of the gaseous fuel mixture. Outer wall member 41 surrounds the heat transfer struc~ure and a flue 42 for the passage of the exhaust gases extends ~o a conventional chimney (not shown). Top plate member 43 is suitably secured to the heat transfer structure and conduit such as by nut and bolt means ~4, part of which may also be embedded in the matrix.
In an exemplary working embodiment a heat transfer unit as described in Figures 1 through 3 inclusive having dimensions of about five inches in diameter and about five inches in length was utilized to provide a continuous hot water flow of approximately three gallons per minute. The burner driving the heat transfer unit and all the electrical controls including a thermostat, air filter and safety regulating devices were incorporated into a structure having a height of about six inches, a width of about twelve inches and an overall length of about eighteen inches.
Such a heat transfer module can replace conventional present day hot water heaters of the storage tank variety having diameters of approximately two feet and heights of approximately six feet.
The new improved structure can be very conveniently mounted adjacent to the final utilization point. In view of the exceeding-ly low cost many such devices can also be incorporated with resul-tant savings in cost of piping and plumbing necessary with present day centralized domestic hot water heating systems.
Referring now to Figure 7, the embodiment of the invention ~4~5 shown in Figures 1-3 inclusive together with the appurtenant s~ructures, is collectively referred to as a heat transfer module designated by the numeral 50. An air blower 51 is coupled through the fitting 37 to feed the air and gas mixture into combustion chamber 38. A gas from source 53 which may be any commercially available natural or tank type, is fed through a solenoid control valve 54 and regulator 55 to the inlet 52 in blower 51. Any small size blower of the inexpensive variety should suffice for most applications. The vent 42 extending laterally from the heat transfer module 50 will provide for the egress of the combustion gases to a convenient outlet Due to the efficiency of the hea~
transfer and the fact that the exhaust te~perature is exceedingly low a small vent opening in a wall may be used similar to the type employed in home clothes dryers. No natural draft type chimney is required, which also results in savings in construction costs. The water supply is indicated by numeral 56 and the heated water medium is fed through line 57 to the outlet tap 58 for instant usage A
temperature and pressure relief valve 59 may be disposed in line 57 It i5 thus noted that large storage tanks or boilers utilized in present day hot water generation sources are completely elimina-ted. A compact and unique source is thus disclosed which may be readily installed directly in the area where the use is intended, for example, the bathroom or kitchen.
Associated wiring for the control of the blower as well as the thermostat and ignition controls together with the main solenoid valve for the gas source have not been specifically described since they are readily commercially available and normal techniques incor-porating such means will be followed.
In Figures 8 and 9 a linear array of fluid conduits 61 is embedded within barrier matrix 62 composed of thermally conductive - 12 _ zs bodies as have hereinbefore been described. Upper plate member 63 supports fluid inlet passage means 64 and is secured by fastening means 65 to screws 66 embedded in collar member 67, The optically dense matrix structure 62 surrounds the linear conduits 61 which are embedded therein, the ends of these conduits and the inlet 64 all communicating with a channel 68 in the inner side of collar member 67. A similar end arrangement is disposed at the opposite end of the matrix structure including a lower plate member 71 and adjacent collar member 70 and communicates with an inner channel 68a in collar member 70 with which the adjacent ends of conduits 61 also communicate. A fluid outlet means 72 is supported by the lower collar member 70. Plate member 71 further defines a plurality of passages 73 for a gas-air mixture fed into the device through conduit 74. The ignition means for the combustible fuel within the chamber 75 is furnished by spark plug member 76 supported by upper plate member 63.
Figures 10 and 11 are directed to an embodiment for very high power density applications, In such embodiments conduits 77 and 78 are disposed about a common axis. Outer conduit 77 is closed by conductive plate means 79 and 80 at opposing ends. Inlet member 81 provides for the ingress of a fluid medium and outlet member 82 provides for the egress of the medium in the vaporized or heated state. The inner conduit 78 is open at the ends for the flow of a heated medium such as the gases from a direct oxygen-gas flame along the inner passage 83 of this conduit, with the direction of flow being indicated by the arrow 84. An optically dense barrier matrix structure 85 comprises a plurality of thermally conductive spherical members joined together to define the thermal transfer paths in accordance with the teachings of the invention. The barrier structure 85 occupies a major portion of the cross-sectional :1~4~(~Z5 area o the conduit 78 and the characteristic dimension of this member will be the inner diameter of the circular conduit as designated by the arrow 86 and symbol C.D.
A similar barrier matrix 87 occupies the cross-sectional area of the outer conduit 77. With the internal barrier matrix structure 85 occupying only a portion of *he overall length of the passage 83 for concentration of the hsated medium, the heat trans-fer area between the medium in the respecti~e conduits will occur substan~ially in the region indicated by the bracket 88. This configuration then provides for high power density applications.
An example of the application of the previously enumerated equation (l) in the transfer of heat from an intense heat source may be noted in the high power density embodiment of Figures lO and 11, Utilizing a direct flame source we assume that a power density of lO,000 watts per square inch of flame area is obtained and yet silver brazed copper members may be employed. Additionally, it is assumed that a desired temperature drop of 100 degrees Fahrenheit is specified, Copper has a thermal conductivity value of about 200 BTU/hour/ft/F. In the final structure we assume that a lower conductivity will be realized due to the brazed joints and optical density of the thermal paths. A conductivity factor of 50 percent then will provide a reliable design factor. Utilizing the other known values the heat path ~L) is calculated as follows:
L = lO0 X 16 = 2 X lO 2 feet = 1/4 inch The characteristic dimension will then be twice the heat path value or l/2 inch. A thermally conductive body average size of between one-quarter and one-twelfth of an inch therefore is indicated for the required optimum optical density. A one-third value or one-sixth of an inch for thermal body size is preferred in most applica-tions ~a~o~s In Flgure 12 another embodiment is illustrated. A helical conduit having a plurality o~ turns 90 iB embedded within a matrix 91 of the external type. If we provide the proper design criteria for the matrix members surround-ing the conduit the interior passages thereof may be filled with other conduc-tive members which need not meet these same critical requirements. Hence, in applications where steam is generated and in condensation devices particles such as mesh, wires, shavings, cuttings and the like can be employed, as indi-cated collectively by numeral 92. Such a configuration for the obstructions within the conduit will provide for even ~ider application of the invention in industry As can be seen from any figure of the drawings, e.g. Fig. 1, the gas passage length through the sintered matrix o~ spheres 31 preferably does not substantially exceed seven l~yers of balls, or approximately 15 times the average radius of curvature of the passage surfaces, and the average radius of curvature of the spheres 31 is substantially less than the radius of curvature o~ the interior surface of condult 30.
The advantages of compactness and efficiency of the disclosed thermal transfer device ln the provision of vastly improved power densities through the optically dense matrix structure will now be apparent to those skllled in the art from thls description. The design criteria o~ the number o~ bonded ~oints along the heat path and the average size of the thermally conductive bodies in relation to the characteristic d~mension to provide the desired optical density have been carefully enumerated. The foregoing dis-cussion and exemplary application of the equation will also assist in the practice of the invention. In addition to the exemplary embodiments numerous other configurations will be evident for other applications. For example, the thermally conductive body members in contact with the outermost wall surfaces of circular conduiis shown in Figs. 1 and 8 may be eliminated, thereby exposing this portion of the boundary interface conduit walls. The heat transfer paths within the matrix between the spaced conduit members would still be defined in accordance with this invention by the thermally conductive bodies in the fluid flow path.
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A heat exchange structure for transferring heat between first and second fluid media through a thermally conductive rigid structure which in-corporates a passageway for the first medium and a plurality of flow paths for the second medium, which paths are defined between a plurality of layers of bodies which are bonded together and to the portions of said structure forming said passageway in regions of contact therewith forming a matrix and whose surfaces, which form the elemental surface areas of the flow paths,are predominantly convexly curved in all directions, wherein the average length of the flow paths is not greater than 15 times the average radius of curva-ture of the said elemental surface areas.
2. A heat exchange structure according to claim 1, wherein the said bodies are spheres.
3. A heat exchange structure according to claim 1, wherein the matrix comprises not more than seven layers of substantially spherical bodies in the direction of flow of the second medium therethrough.
4. A heat exchange structure according to claim 1, 2 or 3, and includ-ing heat source means and blower means for directing a flow of the second medium to and through the flow paths at such a velocity and temperature dif-ferential with respect to the rigid structure that the heat transfer rate between the second medium and the rigid structure exceeds 100 watts per square inch of the surface area of the passageway for the first medium.
5. A heat exchange structure according to claim 1, 2 or 3, and includ-ing heat source means and blower means for directing a flow of the second medium to and through the flow paths at such a velocity and temperature dif-ferential with respect to the rigid structure that the heat transfer rate between the second medium and the rigid structure exceeds 100 watts per square inch of the surface area of the passageway for the first medium, and wherein the said means for providing and directing comprise means for generating the second medium as the products of combustion of a fuel.
6. A heat exchange structure according to claim 1, 2 or 3, and including a burner arranged to supply the second medium as the products of combustion of an air-gas mixture mixed before reaching the matrix of bodies.
7. A heat exchange structure according to claim 1, 2 or 3, and including a burner arranged to supply the second medium as the products of combustion of an air-gas mixture mixed before reaching the matrix of bodies, wherein the burner comprises a combustion chamber surrounded by the matrix of bodies.
8. A heat exchange structure according to claim 1, 2 or 3, wherein the matrix is formed within a conduit around which the said passageway is provided and wherein the average length of the flow paths is less than twice the distance between thermal transfer interface boundaries of the conduit.
9. A heat exchange structure according to claim 1, 2 or 3, wherein the said passageway comprises a plurality of tubular elements embedded in the matrix.
10. A heat exchange structure according to claim 1, 2 or 3, wherein the said passageway comprises a plurality of tubular channels through the matrix.
11. A heat exchange structure according to claim 1, 2 or 3, wherein the said passageway comprises a helical tubular channel through the matrix.
12. A heat exchange structure according to claim 1, 2 or 3, wherein the said passageway comprises a plurality of tubular channels through the matrix, and wherein the matrix surrounds a central plenum from which the second medium flows out substantially radially through the said flow paths.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA278,106A CA1042418A (en) | 1968-01-24 | 1977-05-10 | Heat transfer structure |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US70019268A | 1968-01-24 | 1968-01-24 | |
| US73713568A | 1968-06-14 | 1968-06-14 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040025A true CA1040025A (en) | 1978-10-10 |
Family
ID=27106564
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA038,832A Expired CA1040025A (en) | 1968-01-24 | 1968-12-27 | Heat transfer structure |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS5113909B1 (en) |
| AT (1) | AT327244B (en) |
| BE (1) | BE734306A (en) |
| CA (1) | CA1040025A (en) |
| CH (1) | CH514114A (en) |
| DE (2) | DE6901693U (en) |
| ES (2) | ES362674A1 (en) |
| FR (1) | FR2000669B1 (en) |
| GB (1) | GB1246581A (en) |
| LU (1) | LU58874A1 (en) |
| NL (1) | NL6901052A (en) |
| NO (1) | NO125510B (en) |
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| CN102472591A (en) * | 2009-07-09 | 2012-05-23 | 国际壳牌研究有限公司 | Heat exchanger |
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| US3704748A (en) * | 1970-02-11 | 1972-12-05 | Ratheon Co | Heat transfer structure |
| CA1044695A (en) * | 1970-03-02 | 1978-12-19 | American Standard Inc. | Heat exchanger structure for a compact boiler and the like |
| JPS56146701U (en) * | 1980-04-02 | 1981-11-05 | ||
| JPS56170203U (en) * | 1980-05-16 | 1981-12-16 | ||
| US5224657A (en) * | 1989-05-23 | 1993-07-06 | Kabushiki Kaisha Toshiba | Cryogenic refrigerator |
| EP0399813B1 (en) * | 1989-05-23 | 1993-10-06 | Kabushiki Kaisha Toshiba | Cryogenic refrigerator |
| FR2682464A1 (en) * | 1991-10-10 | 1993-04-16 | Elf Aquitaine | METHOD FOR IMPROVING HEAT AND MASS TRANSFERS TO AND / OR THROUGH A WALL. |
| DE19834295A1 (en) * | 1998-07-29 | 2000-02-10 | Inoevt Beyersdorf Keg Lienz | Flowing medium heating apparatus, useful for a water and-or steam heating system, comprises a heated chamber containing heat storage and-or conductive granules |
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| WO2019008006A1 (en) * | 2017-07-07 | 2019-01-10 | Bekaert Combustion Technology B.V. | Cast segment for a sectional heat exchanger |
| KR20200093547A (en) | 2017-11-29 | 2020-08-05 | 콘데보 에스.피.에이. | Heat exchange cell and method |
| CN109060495B (en) * | 2018-09-11 | 2024-03-15 | 四川省机械研究设计院(集团)有限公司 | Device capable of adjusting thermal resistance |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB191017560A (en) * | 1910-07-25 | 1911-06-21 | William Arthur Bone | Improvements in and relating to Steam Generators. |
| FR538935A (en) * | 1916-10-14 | 1922-06-17 | Apparatus and method for heat transfer | |
| DE895459C (en) * | 1951-12-23 | 1953-11-02 | Metallgesellschaft Ag | Long pipe heat exchanger |
| GB1015306A (en) * | 1963-06-05 | 1965-12-31 | Bendix Corp | Improvements in and relating to tube type heat exchangers |
| US3306353A (en) * | 1964-12-23 | 1967-02-28 | Olin Mathieson | Heat exchanger with sintered metal matrix around tubes |
-
1968
- 1968-12-27 CA CA038,832A patent/CA1040025A/en not_active Expired
-
1969
- 1969-01-09 GB GB0478/69A patent/GB1246581A/en not_active Expired
- 1969-01-17 DE DE6901693U patent/DE6901693U/en not_active Expired
- 1969-01-17 DE DE19691966650 patent/DE1966650A1/en active Pending
- 1969-01-18 ES ES362674A patent/ES362674A1/en not_active Expired
- 1969-01-22 NL NL6901052A patent/NL6901052A/xx unknown
- 1969-01-23 JP JP44004471A patent/JPS5113909B1/ja active Pending
- 1969-01-23 NO NO0270/69A patent/NO125510B/no unknown
- 1969-01-24 FR FR696901317A patent/FR2000669B1/fr not_active Expired
- 1969-05-30 CH CH830469A patent/CH514114A/en not_active IP Right Cessation
- 1969-06-09 BE BE734306D patent/BE734306A/xx unknown
- 1969-06-13 AT AT566069A patent/AT327244B/en not_active IP Right Cessation
- 1969-06-13 LU LU58874D patent/LU58874A1/xx unknown
-
1970
- 1970-02-16 ES ES376609A patent/ES376609A1/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102472591A (en) * | 2009-07-09 | 2012-05-23 | 国际壳牌研究有限公司 | Heat exchanger |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2000669A1 (en) | 1969-09-12 |
| NL6901052A (en) | 1969-07-28 |
| FR2000669B1 (en) | 1974-02-22 |
| ES362674A1 (en) | 1971-02-01 |
| ATA566069A (en) | 1975-04-15 |
| JPS5113909B1 (en) | 1976-05-04 |
| LU58874A1 (en) | 1970-01-14 |
| CH514114A (en) | 1971-10-15 |
| GB1246581A (en) | 1971-09-15 |
| ES376609A1 (en) | 1972-09-16 |
| DE1966650A1 (en) | 1973-05-24 |
| BE734306A (en) | 1969-11-17 |
| NO125510B (en) | 1972-09-18 |
| DE1902229B2 (en) | 1972-09-07 |
| DE6901693U (en) | 1970-06-11 |
| DE1902229A1 (en) | 1969-10-16 |
| AT327244B (en) | 1976-01-26 |
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