GB1587730A - Heat transfer elements - Google Patents

Heat transfer elements Download PDF

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Publication number
GB1587730A
GB1587730A GB3412276A GB3412276A GB1587730A GB 1587730 A GB1587730 A GB 1587730A GB 3412276 A GB3412276 A GB 3412276A GB 3412276 A GB3412276 A GB 3412276A GB 1587730 A GB1587730 A GB 1587730A
Authority
GB
United Kingdom
Prior art keywords
panel
heat transfer
wall member
thermal conductivity
transfer element
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
Application number
GB3412276A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
United Wire Group Ltd
Original Assignee
United Wire Group Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by United Wire Group Ltd filed Critical United Wire Group Ltd
Priority to GB3412276A priority Critical patent/GB1587730A/en
Publication of GB1587730A publication Critical patent/GB1587730A/en
Expired legal-status Critical Current

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00Tubular elements; Assemblies of tubular elements
    • F28F1/10Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/42Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element
    • F28F1/424Means comprising outside portions integral with inside portions
    • F28F1/426Means comprising outside portions integral with inside portions the outside portions and the inside portions forming parts of complementary shape, e.g. concave and convex
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F1/00Tubular elements; Assemblies of tubular elements
    • F28F1/10Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
    • F28F1/42Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being both outside and inside the tubular element
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F13/00Arrangements for modifying heat-transfer, e.g. increasing, decreasing
    • F28F13/14Arrangements for modifying heat-transfer, e.g. increasing, decreasing by endowing the walls of conduits with zones of different degrees of conduction of heat
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F3/00Plate-like or laminated elements; Assemblies of plate-like or laminated elements
    • F28F3/02Elements or assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with recesses, with corrugations

Description

(54) HEAT TRANSFER ELEMENTS (71) 'We, UNITED WIRE GROUP LIMITED, a British Company, of Granton Park Avenue, Edinburgh EHS 1HT, Scotland, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to heat transfer elements, and particularly to heat transfer panels or tubes serving for the conduction of heat between zones on either side thereof.
Heat transfer elements in the form of plain or curved panels are known, which panels alone or in combination serve to form a barrier between zones of hot and cold fluids while being adapted to transmit heat by conduction from the hot zone to the cold zone.
Elements in the form of tubes or pipes operate similarly. For satisfactory heat con duction, these elements are made of a material having a suitably high coefficient of thermal conductivity. Where there is a large boundary between the zones, as is usually the case for effective heat transfer, a large element area is required and since materials of high thermal conductivity are relatively more expensive it is a disadvantage of these barriers that they can be costly.
It is an object of the present invention to obviate or mitigate this disadvantage.
According to one aspect of the present invention a heat transfer element comprises a base wall member, a plurality of apertures extending though the wall member to the opposed outer surfaces of the wall member, said apertures widening as they approach the outer surfaces of the wall member, so as to have a waisted middle part, said apertures being filled with a material of higher thermal conductivity than the material of the wall member, and a layer of higher thermal conductivity material on at least one outer surface of the wall member.
Preferably the transversely extending portion has parts projecting from at least one outer surface of the wall portion: these parts can constitute protuberances for creating turbulent fluid flow at said one outer surface of the wall portion.
The panel should be -made of materials permitting operation at elevated temperature.
The higher thermal conductivity part can be made of a noble metal, silver, copper or other material of suitably high thermal conductivity.
The outer surfaces of the wall member can be of any suitable configuration, but preferably at least one surface is of undulating form with the material filled bores extending from the troughs and crests of the undulations. The base wall member is preferably made from a plastics material for cheapness, for example, a polymer.
Preferably, the bore fillings project as rods from at least one outer surface of the wall.
According to a further aspect of the present invention a method of making a heat transfer element comprises forming a base wall member from one material, forming apertures in the wall member extending transversely between the outer surfaces thereof arranging that said apertures widen as they approach the outer surfaces of the wall member so as to have a waisted middle part, filling said apertures with another material of higher thermal conductivity and additionally applying a layer of material to at least one surface of the wall member, said layer being formed from material of higher thermal conductivity than the base wall material. In a preferred embodiment layers of higher thermal conductivity material are formed on both outer wall surfaces.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 shows a sectional end view of a heat transfer panel according to a first embodiment of the present invention; Fig. 2 shows a sectional end view of a heat transfer panel according to a second embodiment of the present invention.
Referring to Figs. 1 and 2, a heat transfer panel 1 or wall part is fabricated from a sheet of plastics material 2 (thermosetting or thermoplastic), polymerised material, acetylene, vinyl or similar, glass or ceramic material. The panel can be moulded to the required form, and in the embodiment shown has a corrugated form, but the surfaces could be outer surfaces of flat or of other configuration. In particular the panel 1 has a corrugated form having equal corrugation pitch P and equal corrugation amplitude A.
Alternatively the corrugations may have unequal pitch and unequal amplitude. The cor rugations 3 extend longitudinally but could extend transversely or may be inclined.
Further, the panel 1 could be provided with dimples or recesses, on one or both sides, and these may extend in parallel rows or may be arranged in a reverse or alternating manner.
A series of through-bores 4 is provided in the panel 1 and extending transversely at predetermined intervals and spacings between desired parts of the outer surfaces of the panel 1. In the example shown, the through-bores 4, can be provided at the crests and troughs of the corrugated panel.
These through-bores 4 are fully filled with material which has a high thermal con ductivity and which is capable of resisting corrosion (i.e. is a noble material). The through-bores 4 widen adjacent the outer surfaces. The filling material can be a noble metal such as silver (with the base panel suitably a polyamide sheet) which metal has a coefficient of thermal conductivity (1.00 (gramme) calories cm. per sec. cm2 per degree C) very many times greater than plastics materials (polymers: 4.0-6.0 X 10-4 cals.
cm. per sec. per cm" per degree C).
In the use of a heat exchange panel 1, relatively hot fluid passes on one side of the panel 1 while relatively cold fluid passes on the other side and heat transfer is substantially via the metal filled bores 4. A serious barrier to the transfer of heat occurs in the boundary layers of the hot fluid in contact with the panel and in the relatively slower moving laminer flow regions close to the boundary layer. There is a similar barrier to heat transfer at the cold fluid/panel interface. Conductance of heat which has reached the panel surface is relatively unimpeded transversely across the panel to the other outer wall surface.For any heat transfer, the temperature difference between the main body of the heating fluid and the adjacent outer surface of the heat transfer panel 1 is normally much greater than the temperature difference across the panel itself. The cold fluid/panel temperature differential is also greater than this latter difference. Therefore, for improved efficiency of heat transfer a layer 5 of high thermal conductivity and non-corrosive material is provided on at least one outer surface of the panel,. and preferably on both outer surfaces. Such a layer 5 may be a silver layer. Further, since the metal filled bores 4 widen adjacent the panel outer surfaces instead of being plain cylindrical more efficient heat transfer is possible.The filled bores 4 and layers 5 can be formed for example by electro-plating or dipping etc.
The above heat transfer panel according to the present invention has the high thermal conductivity material 4, 5 positioned at the most useful locations in the panel 1. Since plastics materials are considerably cheaper and more easily worked than noble metals, and stainless steels, the above panel will be cheaper than a panel made solely of the metal, but the panel will have a higher efficiency of heat transfer than a pure plastics panel.
In the embodiment shown in Fig. 2, the material of the bores 4 is arranged to extend as rods 6 from one or both outer surfaces of the panel 1. These projecting rods serve as turbulence promoters, droplet promoters for condensing vapours and thermal collectors or distributors to the fluids in contact or "en passant".
It will be appreciated that heat transfer pipes or tubes could be made embodying the inventive features of the above panels according to the present invention. Panels or tubes according to the present invention should find particular application in internal combustion engines, in other prime movers and also for example in solar cells; all applications where the conductance of heat is a vital factor. The-invention can also mitigate eddy current losses.
WHAT WE CLAIM IS:- 1. A heat transfer element comprising a base wall member, a plurality of apertures extending through the wall member to the opposed outer surfaces of the wall member, said apertures widening as they approach the outer surfaces of the wall member, so as to have a waisted middle part, said apertures being filled with a material of higher thermal conductivity that the material of the wall member, and a layer of higher thermal conductivity material on at least one outer surface of the wall member.
2. A heat transfer element as claimed in claim 1 wherein the aperture fillings project from at least one outer surface of the wall member.
3. A heat transfer element as claimed in claim 1 or 2, wherein the higher thermal conductivity material is a metal capable of resisting corrosion.
4. A heat transfer element as claimed in any one of the preceding claims, wherein a layer of higher thermal conductivity material is provided on each outer surface of the wall member.
5. A heat transfer element as claimed in
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (15)

**WARNING** start of CLMS field may overlap end of DESC **. or thermoplastic), polymerised material, acetylene, vinyl or similar, glass or ceramic material. The panel can be moulded to the required form, and in the embodiment shown has a corrugated form, but the surfaces could be outer surfaces of flat or of other configuration. In particular the panel 1 has a corrugated form having equal corrugation pitch P and equal corrugation amplitude A. Alternatively the corrugations may have unequal pitch and unequal amplitude. The cor rugations 3 extend longitudinally but could extend transversely or may be inclined. Further, the panel 1 could be provided with dimples or recesses, on one or both sides, and these may extend in parallel rows or may be arranged in a reverse or alternating manner. A series of through-bores 4 is provided in the panel 1 and extending transversely at predetermined intervals and spacings between desired parts of the outer surfaces of the panel 1. In the example shown, the through-bores 4, can be provided at the crests and troughs of the corrugated panel. These through-bores 4 are fully filled with material which has a high thermal con ductivity and which is capable of resisting corrosion (i.e. is a noble material). The through-bores 4 widen adjacent the outer surfaces. The filling material can be a noble metal such as silver (with the base panel suitably a polyamide sheet) which metal has a coefficient of thermal conductivity (1.00 (gramme) calories cm. per sec. cm2 per degree C) very many times greater than plastics materials (polymers: 4.0-6.0 X 10-4 cals. cm. per sec. per cm" per degree C). In the use of a heat exchange panel 1, relatively hot fluid passes on one side of the panel 1 while relatively cold fluid passes on the other side and heat transfer is substantially via the metal filled bores 4. A serious barrier to the transfer of heat occurs in the boundary layers of the hot fluid in contact with the panel and in the relatively slower moving laminer flow regions close to the boundary layer. There is a similar barrier to heat transfer at the cold fluid/panel interface. Conductance of heat which has reached the panel surface is relatively unimpeded transversely across the panel to the other outer wall surface.For any heat transfer, the temperature difference between the main body of the heating fluid and the adjacent outer surface of the heat transfer panel 1 is normally much greater than the temperature difference across the panel itself. The cold fluid/panel temperature differential is also greater than this latter difference. Therefore, for improved efficiency of heat transfer a layer 5 of high thermal conductivity and non-corrosive material is provided on at least one outer surface of the panel,. and preferably on both outer surfaces. Such a layer 5 may be a silver layer. Further, since the metal filled bores 4 widen adjacent the panel outer surfaces instead of being plain cylindrical more efficient heat transfer is possible.The filled bores 4 and layers 5 can be formed for example by electro-plating or dipping etc. The above heat transfer panel according to the present invention has the high thermal conductivity material 4, 5 positioned at the most useful locations in the panel 1. Since plastics materials are considerably cheaper and more easily worked than noble metals, and stainless steels, the above panel will be cheaper than a panel made solely of the metal, but the panel will have a higher efficiency of heat transfer than a pure plastics panel. In the embodiment shown in Fig. 2, the material of the bores 4 is arranged to extend as rods 6 from one or both outer surfaces of the panel 1. These projecting rods serve as turbulence promoters, droplet promoters for condensing vapours and thermal collectors or distributors to the fluids in contact or "en passant". It will be appreciated that heat transfer pipes or tubes could be made embodying the inventive features of the above panels according to the present invention. Panels or tubes according to the present invention should find particular application in internal combustion engines, in other prime movers and also for example in solar cells; all applications where the conductance of heat is a vital factor. The-invention can also mitigate eddy current losses. WHAT WE CLAIM IS:-
1. A heat transfer element comprising a base wall member, a plurality of apertures extending through the wall member to the opposed outer surfaces of the wall member, said apertures widening as they approach the outer surfaces of the wall member, so as to have a waisted middle part, said apertures being filled with a material of higher thermal conductivity that the material of the wall member, and a layer of higher thermal conductivity material on at least one outer surface of the wall member.
2. A heat transfer element as claimed in claim 1 wherein the aperture fillings project from at least one outer surface of the wall member.
3. A heat transfer element as claimed in claim 1 or 2, wherein the higher thermal conductivity material is a metal capable of resisting corrosion.
4. A heat transfer element as claimed in any one of the preceding claims, wherein a layer of higher thermal conductivity material is provided on each outer surface of the wall member.
5. A heat transfer element as claimed in
any one of the preceding claims, wherein at least one surface is of undulating form with the material filled apertures extending from the troughs and crests of the undulations.
6. A heat transfer element as claimed in any one of the preceding claims wherein the wall member is made of plastics material.
7. A heat transfer element as claimed in claim 6, wherein the plastics material is a polymer.
8. A heat transfer element as claimed in any one of the preceding claims, wherein the higher thermal conductivity portion is a noble metal.
9. A heat transfer element as claimed in claim 8, wherein the noble metal is silver.
10. A method of making a heat transfer element comprising forming a base wall member from one material, forming apertures in the wall member extending transversely between the outer surfaces thereof arranging that said apertures widen as they approach the outer surfaces of the wall member so as to have a waisted middle part, filling said apertures with another material of higher thermal conductivity and additionally applying a layer of material to at least one surface of the wall member, said layer being formed from material of higher thermal conductivity than the base wall material.
11. A method as claimed in claim 10, wherein said layers of material are formed on both outer surfaces.
12. A method as claimed in claim 10, wherein the higher thermal conductivity material is applied by electro-plating or by dipping.
13. A method of making a heat transfer element substantially as hereinbefore described.
14. A heat transfer element made according to the method of any one of claims 10 to 13.
15. A heat transfer element substantially as hereinbefore described with reference to and as illustrated in Fig. 1 or Fig. 2 of the accompanying drawings.
GB3412276A 1977-11-16 1977-11-16 Heat transfer elements Expired GB1587730A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB3412276A GB1587730A (en) 1977-11-16 1977-11-16 Heat transfer elements

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB3412276A GB1587730A (en) 1977-11-16 1977-11-16 Heat transfer elements

Publications (1)

Publication Number Publication Date
GB1587730A true GB1587730A (en) 1981-04-08

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB3412276A Expired GB1587730A (en) 1977-11-16 1977-11-16 Heat transfer elements

Country Status (1)

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GB (1) GB1587730A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2122738A (en) * 1982-05-26 1984-01-18 Hitachi Ltd Heat exchanger
US4999741A (en) * 1988-01-26 1991-03-12 The General Electric Company, P.L.C. Package in the heat dissipation of Electronic devices

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2122738A (en) * 1982-05-26 1984-01-18 Hitachi Ltd Heat exchanger
US4999741A (en) * 1988-01-26 1991-03-12 The General Electric Company, P.L.C. Package in the heat dissipation of Electronic devices

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PS Patent sealed
PCNP Patent ceased through non-payment of renewal fee