GB1574207A - Heat exchanger - Google Patents

Heat exchanger Download PDF

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Publication number
GB1574207A
GB1574207A GB17492/76A GB1749276A GB1574207A GB 1574207 A GB1574207 A GB 1574207A GB 17492/76 A GB17492/76 A GB 17492/76A GB 1749276 A GB1749276 A GB 1749276A GB 1574207 A GB1574207 A GB 1574207A
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GB
United Kingdom
Prior art keywords
board
heat exchanger
header
groove
exchanger according
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
GB17492/76A
Inventor
D S Brackman
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.)
Imperial Chemical Industries Ltd
Original Assignee
Imperial Chemical Industries 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 Imperial Chemical Industries Ltd filed Critical Imperial Chemical Industries Ltd
Priority to GB17492/76A priority Critical patent/GB1574207A/en
Priority to ZA00772434A priority patent/ZA772434B/en
Priority to US05/790,002 priority patent/US4150720A/en
Priority to NZ183930A priority patent/NZ183930A/en
Priority to AU24643/77A priority patent/AU502272B2/en
Priority to JP4860377A priority patent/JPS52144850A/en
Priority to BR7702719A priority patent/BR7702719A/en
Priority to CA277,409A priority patent/CA1076555A/en
Priority to FR7712965A priority patent/FR2349811A1/en
Priority to DE2719273A priority patent/DE2719273C3/en
Priority to AT0307277A priority patent/AT368622B/en
Priority to IT2304077A priority patent/IT1075648B/en
Publication of GB1574207A publication Critical patent/GB1574207A/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
    • F28F21/00Constructions of heat-exchange apparatus characterised by the selection of particular materials
    • F28F21/06Constructions of heat-exchange apparatus characterised by the selection of particular materials of plastics material
    • F28F21/065Constructions of heat-exchange apparatus characterised by the selection of particular materials of plastics material the heat-exchange apparatus employing plate-like or laminated conduits
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24SSOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS
    • F24S10/00Solar heat collectors using working fluids
    • F24S10/50Solar heat collectors using working fluids the working fluids being conveyed between plates
    • F24S10/502Solar heat collectors using working fluids the working fluids being conveyed between plates having conduits formed by paired plates and internal partition means
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28HEAT EXCHANGE IN GENERAL
    • F28FDETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02Header boxes; End plates
    • F28F9/0243Header boxes having a circular cross-section
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/40Solar thermal energy, e.g. solar towers
    • Y02E10/44Heat exchange systems

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Description

(54) HEAT EXCHANGER (71) We, IMPERIAL CHEMICAL INDUS TRIES LIMITED, Imperial House, Millbank, London SW1P 3fF, a British Company, 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 invention relates to heat exchangers of thermoplastics materials.
The invention provides a heat exchanger of thermoplastics material comprising two spaced-apart tubular headers interconnected by a hollow extruded board comprising a plurality of tubular passages extending from one end of the board to the other; each header having a longitudinal groove in its exterior surface and a plurality of holes spaced along the base of the groove, the holes interconnecting the groove and the interior of the header; the tubular passages having openings at or near each end of the board and the board being located along the grooves of the respective headers so that the openings are positioned to 'provide with said holes interconnection between the interiors of the headers and the tubular passages; each header being held in position by a sealing bead adhering to both the header and the board, and extending continuously right round the mouth of the groove where covered by the board, to seal against loss of any fluid flowing between the header and the tubular passages of the board.
When operating this heat exchanger, the two headers are connected to an external circuit and the system filled with a suitable fluid, such as water The fluid is then caused to flow from the external circuit into one header, through the holes, and then into and along the plurality of tubular ,passages in the extruded board where it either picks up or loses heat to the environment. At the other end of the tubular passages, the fluid flows through the holes into that other header, and eventually out into the external circuit again. The fluid may suitably be caused to circulate by a pump, although in some applications, thermo-siphoning effects due to the temperature difference across the heat exchanger, may be sufficient.
The heat exchangers may be used singly or a plurality of similar exchangers may be connected together to form an array. For efficient working, it is desirable to have uniform flow through all the tubular passages, and this also applies throughout a full array of such heat exchangers. This uniform even flow may be achieved in a flat panel by using a diagonal flow pattern with the fluid entering at one end of one header and leaving from the opposite end of the other header. Uniform distribution of the fluid to the various tubular passages along the width of the board may be assisted by leaving the grooves sufficiently clear to permit free flow of fluid along them. This may be achieved by mounting the board at the mouth of the groove.However, it is difficult in practice to extrude the sealing bead forcibly into contact with both the board and the header while maintaining their alignment and also while ensuring that the sealing material does not enter the groove or the ends of the tubular passages, with consequent restriction (or even blockage) of fluid flow during use.
These problems can be avoided by inserting the ends of the board at least part-way into the header grooves to provide positive location and avoid ingress of sealer, and such heat exchangers are preferred. Free flow of fluid along the groove may still be achieved by preventing the board from reaching the base of the groove (e.g. by using a groove whose width at its mouth is sufficient to accommodate the end of the board but which narrows e.g. stepwise or by tapering, te a width insufficient to accommodate the board at a point part-way between the mouth of the groove and its base, or by inserting temporary water-soluble spacers at the base of the groove) or by shaping the end of the board such that part thereof is held clear of the base of the groove to allow free flow of fluid along the groove, by a further part 7 thereof which extends to the base of the groovy In constructing the heat exchanger, it is desirable to avoid restricting the flow of the fluid through it.There are various reasons for this Thus, for example, a restricted flow requires more energy, and indeed, adequate circulation of the fluid by thermo-siphon effects alone may be prevented if flow is restricted. Restricted passages are more likely to become blocked during use, and it would be more difficult to obtain uniform flow because it would then be necessary to ensure that the restrictions were all the same for each tubular passage, because without restrictions or other such adverse factors, the diagonal flow pattern tends to give a suh stantially uniform flow pattern across the board.
The total area of the holes spaced along the length of the header groove, is therefore preferably sufficient to permit fluid to flow at a rate sufficient for the particular application without substantially restricting the flow. The holes may be round, formed for example by drilling, or they may be elongated to form slots where a greater area is required. However, as there are a plurality of holes according t6 this invention, there must necessarily be at least one (and preferably many more) portion between the holes, bridging between the two sides of the groove.
The purpose of these bridging portions is to carry the stresses within the headers.
rather than transfer them to the relatively thin sections of the board. Preferred holes are rectangular-sectioned, and arranged with adjacent sides substantially parallel. The rectangular-sectioned holes provide a larger flow passage area for any specific width of bridging portion than corresponding circular holes. For particularly arduous conditions it is preferred to provide rectangular holes with one side longer than the other, the holes being aligned with their longer sides adjacent. For most applications, substantially square-sectioned holes are suitable, and for lower stress conditions, the holes may be elongated along the direction of the line of holes.
At the interface between the end of the tubular passages and the adjacent surface of the header where the holes emerge, the total area of the flow passage cross-section will be reduced by the thickness of both the bridging portions and the webs unless there is complete coincidene between them, unless the structure is proportional to avoid that.
Hence in a preferred heat exchanger the bridging portions are narrowed substantially to a knife edge at their outer surface. The internal width of the tubular passages from one side of the board to the other is also preferably less than the width of the holes through the header by an amount such that the total cross-sectional area of the holes is substantially equal to or greater than the total cross-sectional area of the tubular passages. By reducing the thickness of the bridging portions to a knife edge, there is no significant reduction of the flow passage area at the interface which might otherwise cause some restriction in flow. Likewise by broadening the holes, reduction in the flow passage area may be avoided while allowing adequate bridging material for carrying the stresses within the header pipe.
The knife edge may be obtained by tapering the holes over the full thickness of the header wall. However, it is preferred to merely chamfer the bridging portions at their outer surface so as to provide the maximum quantity of material in each bridging portion while still avoiding restriction of the flow.
The chamfer may be on one or both sides of the bridging portion, a unilateral chamfer being preferred.
The boards may be extruded in the manner described in British Patent Specification 1,042,732, wherein Figures 1 to 4 show various board profiles, each of which comprises tubular passages extending from one end of the board to the other, and could be used in the present application. However, as thermoplastics materials are generally of low thermal conductivity, it is preferable for the board to have a profile which minimises the amount of conduction required to dissipate the heat over the surface of the board or to collect heat from all over the surface.
Preferred configurations of the four shown therein are those of Figure 1 wherein the tubular passages are substantially square in section, and Figure 4 wherein the passages each have a domed roof and thicker-sec- tioned webs between the passages. Examples of heat exchangers having boards of these two preferred configurations are illustrated in Figures 4 and 5 respectively of the accompanying drawings.
The heat exchanger may be used for extracting heat from its environment, e.g.
as a solar energy collector. For this application the headers and especially the board may be extruded from a thermoplastics material (preferably a stabilised grade of polypropylene) which is either pigmented or coated with a solar radiation-absorbing colour, e.g. black. Water circulated through such a panel exposed to the sun may become warmer, and be used as a low grade heat supply suitable for heating e.g. swimming pools (where it may be convenient to use the pool's own pump to circulate the water being filtered, around the panel or preferably array of panels), greenhouses or buildings.
The heat exchangers may be used to supply heat to the environment, by circulating water which is warmer than the environment. The heat exchanger may, for example, be used as a radiator in a central heating system of a building, as a greenhouse heater, or even as a direct soil heater when buried in the soil of a greenhouse or cold frame.
The water for such applications may be warmed by solar energy, collected for example by a further heat exchanger according to the invention when adapted as a solar collector as described above.
The invention is illustrated by various specific embodiments, described hereinafter by way of example with reference to Figures 1 to 3 of the drawings accompanying the Provisional Specification and Application No. 17492/76, and to Figures 4 to 7 of the accompanying drawings of which Figures 6 and 7 are renumbered equivalents of Figures 3 and 4 of the drawings accompanying the Provisional Specification of Application No. 50093/76. In the drawings, Figure 1 is a cut-away isometric view of an end portion of a heat exchanger in which the board extends radially from the header, Figure 2 is a transverse section through one end of a further heat exchanger similar to that shown in Figure 1.
Figure 3 is a transverse section through a further heat exchanger having a facemounted header, Figures 4 and 5 are cut-away views of two further heat exchangers, and Figures 6 and 7 are mutually perpendicular sections through a still further heat exchanger.
The embodiment illustrated in Figure 1 comprises a thick-walled polypropylene extruded tube 1 which forms the header, and an extruded board 2 extending radially from the header. The board comprises two spaced-apart sheets 3, 4 connected by a plurality of parallel webs 5 subdividing the space between the sheets into a plurality of parallel tubular passages 6 of rectangular section. The boards are extruded from polypropylene with the webs and sheets being extruded together as integral parts of a common extrudate. Running longitudinally along the header is a groove 7 milled into its external surface, the groove having a length and width substantially the same as the width and thickness respectively of the board. Spaced along the groove are a plurality of holes 8 interconnecting the groove and the interior 9 of the header.The end of the board is located along the mouth of the groove with the tubular passages opening into the groove. Along the angle formed between the header and the board is a sealing bead 10, which is fused to both parts, and not only holds them firmly to gether, but also seals the joint against escape of fluid. The board continues beyond the edge which has been sectioned to show the profile of the board, until it reaches a second header whiclh is Iparallel to and substantially the same as that shown.
The heat exchanger is made by -first milling the grooves 7 in the two headers, and drilling the row of holes along the base of each groove, through to the interior of the header. The headers and board are held in a jig with the ends of the board lying along the mouths of the two grooves, and polypropylene (e.g. a low ethylene composition) extruded as a bead progressively along the joint, into contact with the board and header, suitable melt temperatures being around 2800C. The extruder tip may be allowed to touch the header (but not the board) immediately prior to the bead of molten polymer. The molten polymer melts the surface of both the board and the header, and on cooling forms a firm weld to each.
In use, the headers are connected into an external circuit as required, and a fluid circulated through it. The fluid enters one header through an inlet at one end, passes through the holes into the groove, and thence into the tubular passages, running along the groove to become distributed to all the passages. After passing through the passages within the board, the fluid enters the groove in the second header, and passes through the holes into the interior of the second header, from which it is returned to the external circuit via an -exit which is diagonally opposite the inlet on the other header.
A similar heat exchanger is shown -in Figure 2, and like numerals have been used for like parts. The only differences are that the board has been inserted into the groove, and a portion 12 has been cut out of the end of each web to allow the fluid to flow along the groove and distribute itself uniformly amongst the tubular passages.
The heat exchanger shown in Figure 3 also comprises a tubular header 31 at each end of a board 32 extruded with a profile substantially as shown in Figure 1. However, instead of the board extending radially from each header, the latter are mounted on one face 33 of the board. The ends of all the tubular passages through the board are closed by sealer 34 extruded into them( an alternative would be to clamp the ends of the sheets together in a heated press), and the board has a slot 35 cut out of the upper sheet adjacent the sealed ends, to provide access to the tubular passages. Mounted over the slots at either ends of the board are the headers 31 extruded with a profile specifically designed for the illustrated application.
Thus while there is again a basic circularsectioned pipe, there are also two integral longitudinal ridges 41 which are parallel and spaced apart sufficiently to provide a groove 42 between them. Interconnecting the groove and the interior 43 of the header, is a row of closely-spaced holes 44, and the headers are secured in place using a bead 45 of sealer extruded into place as described above. However, unlike the embodiments of Figures 1 and 2 in which a groove of the required length only was machined into the surface of the header, the groove of Figure 3 being defined by the continuous integral ridges, extends continuously along the tube, and so extends beyond the edges of the board. The grooves must therefore be sealed where it so extends, e.g.
with the sealer when securing the headers to the board.
Other fixtures may be secured to the heat exchanger in similar manner. Thus for example, mounting lugs may be extrusion welded to the boards or to the headers, if formed of a suitable thermoplastics material.
The heat exchanger shown in Figure 4 is generally similar to that of Figure 1, in comprising a tubular polypropylene header 47 welded to a polypropylene extruded board 48, by an extruded polypropylene bead 49.
The board again comprises two spacedapart sheets 50, the space between which is subdivided by a plurality of webs 51 to provide rectangular-sectioned tubular passages 52. Down the side of the header is a longitudinal groove 53 with holes 54 through to the interior 55 of the header, the material between the holes providing bridging portions 56.
The board 48 is inserted into the groove 53 whereby it is positively located during the welding process. The end of the board lies flush with the base of the groove, but unlike that shown in Figure 2, the webs are not cut away to allow the fluid to flow freely along the groove. Instead, the rectangularsectioned holes 54 through the header are closely spaced to give narrow bridging portions, and the tubular passages are fed directly with little flow (if any) along the groove.
The heat exchanger of Figure 5 is similar to that of Figure 4, except that the upper sheet 57 of the board is corrugated and provides a domed roof to each of the tubular passages. The configuration of this board is substantially as shown in Figure 4 of British Patent Specification 1,042,732 referred to hereinabove. This configuration of board, however, is particularly suitable for use in solar energy collectors as the corrugated upper surface is effective for absorbing radiation as the angle of incidence varies throughout the day. Furthermore, polypropylene is degradable unless it contains at least a minimum effective amount of a suitable stabiliser, and most known stabilisers tend to be very slowly leached by warm water circulating through the heat exchanger.As this leaching can occur from both surfaces of the webs but only from one surface of the sheets, the provision of webs whose minimum thickness is at least twice that of the material separating the tubular passages from the surrounding environment, is also advantageous.
The use of thicker webs, however, may lead to poor flow distribution where flow must be direct from the holes to the passages due to blocking of the passages by the bridging portions 56. Accordingly a small step 58 is provided in one side of the groove to hold the board off the base of the groove during welding. Corresponding steps could equally be formed in both sides of the groove, but that is not generally much advantage with the corrugated configuration of board shown.
Alternatively, the bridging portion may be modified in a manner similar to that of the embodiment shown in Figures 6 and 7. That embodiment comprises a tubular header 61 having a longitudinal groove 62 in which is located the end of a hollow board 63. The board which is held in place by a bead 64, comprises two spaced-apart sheets 65 interconnected by integral webs 66. The webs divide up the space within the hollow board, into parallel tubular passages 67 of rectangular cross-section, which run from one header to the other.
The groove has a flat base 68 against which sits the end of the board. Through the header is a row of rectangular-sectioned holes 69, the material between the holes providing bridging portions 70. The bridging portions are chamfered at their outer surfaces to a knife edge 71 and the holes stretch the full width of the groove into which the board is inserted. Consequently the internal width of the tubular passages is less than that of the holes by an amount equal to the thickness of the two sheets making up the board, and also the clearance allowed either side of the board. The total cross-sectional area of the holes is substantially equal to the total cross-sectional area of the tubular passages so that flow through the passages will not be restricted on passing into the headers.
The bridging portions are important because they carry any stresses which may develop between the parts of the header on either side of the board, rather than the stresses being applied to either side of the relatively thin-walled board. The thickness of the bridging portions and other portions of the header wall are made sufficiently strong to withstand the expected stresses, e.g. the head of the circulating liquid at various temperatures. In the headers shown in Figures 1 and 2, the groove is milled out of the constant wall thickness, thereby considerably weakening the header along the line of the groove, and in consequence a thicker overall section is required.In Figure 3, however, the header is shaped so that the groove lies external to the basic cylindrical shape, and the thickness need be no more than that required to withstand the expected load together with the usual safety tolerances. Similarly, a header is shown in Figure 6 whose configuration avoids undue wastage of material. In this header the wall thickness at the holes is sufficient to Iprovide bridging portions capable Of carrying the stresses developed in use, with a balancing portion 72 of similar thickness diametrically opposite. The two symmetrically-placed portions 73 between them are able to be made thinner without reducing their bursting strength below that at the holes.
WHAT WE CLAIM IS:- 1. A heat exchanger of thermoplastics material comprising two spaced-apart tubular headers interconnected by a hollow extruded board comprising a plurality of tubular passages extending from one end of the board to the other; each header having a longitudinal groove in its exterior surface and a plurality of holes spaced along the base of the groove, the holes interconnecting the groove and the interior of the header; the tubular passages having openings at or near each end of the board and the board being located along the grooves of the respective headers so that the openings are positioned to provide with said holes interconnection between the interiors of the headers and the tubular passages; each header being held in position by a sealing bead adhering to both the header and the board, and extending continuously right round the mouth of the groove where covered by the board, to seal against loss of any fluid flowing between the header and the tubular passages of the board.
2. A heat exchanger according to claim 1 in which the grooves are sufficiently clear to permit free flow of fluid along them.
3. A heat exchanger according to claim 1 or claim 2 in which the ends of the board are inserted at least part-way into the header grooves.
4. A heat exchanger according to claim 3 in which the width of the groove at its mouth is sufficiently wide to accommodate the end of the board but which narrows to a width insufficient to accommodate the board at a point part-way between the mouth of the groove and its base.
5. A heat exchanger according to claim 3 in which the end of the board is shaped such that part thereof is held clear of the base of the groove to allow free flow of fluid along the groove, by a further part thereof which extends to the base of the groove.
6. A heat exchanger according to any one of the preceding claims in which the wall of the header has a longitudinal portion which is thicker than an adjacent longitudinal portion, and in which the groove is formed along the thicker longitudinal portion.
7. A heat exchanger according to claim 6 in which the header has a second thicker longitudinal portion down its opposite side, whereby the transverse section of the header is substantially symmetrical when taking no account of the groove and holes.
8. A heat exchanger according to any one of the preceding claims in which the total area of the holes spaced along the length of the header groove is sufficient to permit fluid to Bow without substantially restricting the flow.
9. A heat exchanger according to any one of the preceding claims in which the holes are rectangular-sectioned and are arranged with adjacent sides substantially parallel.
10. A heat exchanger according to any one of the preceding claims in which the bridging portions between the holes are narrowed substantially to a knife edge at their outer surface.
11. A heat exchanger according to any one of the preceding claims in which the internal width of the tubular passages from one side of the board to the other is less than the width of the holes through the header by an amount such that the total cross-sectional area of the holes is substantially equal to or greater than the total cross-sectional area of the tubular passages.
12. A heat exchanger according to any one of the preceding claims in which the tubular passages through the board are substantially rectangular in seotion.
13. A heat exchanger according to any one of claims 1 to 11 in which the tubular passages each have a domed roof.
14. A heat exchanger according to any one of the preceding claims in which the tubular passages of the board are separated by webs whose minimum thickness is at least twice that of the material separating the tubular passages from the surrounding environment.
15. A heat exchanger according to any one of the preceding claims in which the header and board are both extruded from a polypropylene composition.
16. A heat exchanger according to any one of the preceding claims in which the board is either pigmented or coated with a solar radiation-absorbing colour.
17. A heat exchanger according to any one of the preceding claims in which one of the headers has an inlet at one end and the other header has an outlet at its opposite end whereby the inlet and outlet are at diagonally opposite corners of the heat exchanger.
18. A heat exchanger according to any one of the preceding claims in which the
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (20)

**WARNING** start of CLMS field may overlap end of DESC **. 3, however, the header is shaped so that the groove lies external to the basic cylindrical shape, and the thickness need be no more than that required to withstand the expected load together with the usual safety tolerances. Similarly, a header is shown in Figure 6 whose configuration avoids undue wastage of material. In this header the wall thickness at the holes is sufficient to Iprovide bridging portions capable Of carrying the stresses developed in use, with a balancing portion 72 of similar thickness diametrically opposite. The two symmetrically-placed portions 73 between them are able to be made thinner without reducing their bursting strength below that at the holes. WHAT WE CLAIM IS:-
1. A heat exchanger of thermoplastics material comprising two spaced-apart tubular headers interconnected by a hollow extruded board comprising a plurality of tubular passages extending from one end of the board to the other; each header having a longitudinal groove in its exterior surface and a plurality of holes spaced along the base of the groove, the holes interconnecting the groove and the interior of the header; the tubular passages having openings at or near each end of the board and the board being located along the grooves of the respective headers so that the openings are positioned to provide with said holes interconnection between the interiors of the headers and the tubular passages; each header being held in position by a sealing bead adhering to both the header and the board, and extending continuously right round the mouth of the groove where covered by the board, to seal against loss of any fluid flowing between the header and the tubular passages of the board.
2. A heat exchanger according to claim 1 in which the grooves are sufficiently clear to permit free flow of fluid along them.
3. A heat exchanger according to claim 1 or claim 2 in which the ends of the board are inserted at least part-way into the header grooves.
4. A heat exchanger according to claim 3 in which the width of the groove at its mouth is sufficiently wide to accommodate the end of the board but which narrows to a width insufficient to accommodate the board at a point part-way between the mouth of the groove and its base.
5. A heat exchanger according to claim 3 in which the end of the board is shaped such that part thereof is held clear of the base of the groove to allow free flow of fluid along the groove, by a further part thereof which extends to the base of the groove.
6. A heat exchanger according to any one of the preceding claims in which the wall of the header has a longitudinal portion which is thicker than an adjacent longitudinal portion, and in which the groove is formed along the thicker longitudinal portion.
7. A heat exchanger according to claim 6 in which the header has a second thicker longitudinal portion down its opposite side, whereby the transverse section of the header is substantially symmetrical when taking no account of the groove and holes.
8. A heat exchanger according to any one of the preceding claims in which the total area of the holes spaced along the length of the header groove is sufficient to permit fluid to Bow without substantially restricting the flow.
9. A heat exchanger according to any one of the preceding claims in which the holes are rectangular-sectioned and are arranged with adjacent sides substantially parallel.
10. A heat exchanger according to any one of the preceding claims in which the bridging portions between the holes are narrowed substantially to a knife edge at their outer surface.
11. A heat exchanger according to any one of the preceding claims in which the internal width of the tubular passages from one side of the board to the other is less than the width of the holes through the header by an amount such that the total cross-sectional area of the holes is substantially equal to or greater than the total cross-sectional area of the tubular passages.
12. A heat exchanger according to any one of the preceding claims in which the tubular passages through the board are substantially rectangular in seotion.
13. A heat exchanger according to any one of claims 1 to 11 in which the tubular passages each have a domed roof.
14. A heat exchanger according to any one of the preceding claims in which the tubular passages of the board are separated by webs whose minimum thickness is at least twice that of the material separating the tubular passages from the surrounding environment.
15. A heat exchanger according to any one of the preceding claims in which the header and board are both extruded from a polypropylene composition.
16. A heat exchanger according to any one of the preceding claims in which the board is either pigmented or coated with a solar radiation-absorbing colour.
17. A heat exchanger according to any one of the preceding claims in which one of the headers has an inlet at one end and the other header has an outlet at its opposite end whereby the inlet and outlet are at diagonally opposite corners of the heat exchanger.
18. A heat exchanger according to any one of the preceding claims in which the
headers are welded to either end of the board by extrusion welding.
19. A heat exchanger substantially as hereinbefore described and as shown in any one of Figures 1 to 3 of the drawings accompanying the Provisional Specification of Application No. 17492/76.
20. A heat exchanger substantially as hereinbefore described and as shown in any one of Figures 4 to 7 of the accompanying drawings.
GB17492/76A 1976-04-29 1976-04-29 Heat exchanger Expired GB1574207A (en)

Priority Applications (12)

Application Number Priority Date Filing Date Title
GB17492/76A GB1574207A (en) 1976-04-29 1976-04-29 Heat exchanger
ZA00772434A ZA772434B (en) 1976-04-29 1977-04-22 Heat exchanger
US05/790,002 US4150720A (en) 1976-04-29 1977-04-22 Heat exchanger
NZ183930A NZ183930A (en) 1976-04-29 1977-04-26 Heat exchanger headers interconnected by flow passages
AU24643/77A AU502272B2 (en) 1976-04-29 1977-04-27 Heat exchanger
JP4860377A JPS52144850A (en) 1976-04-29 1977-04-28 Heat exchanger
BR7702719A BR7702719A (en) 1976-04-29 1977-04-28 HEAT EXCHANGER
CA277,409A CA1076555A (en) 1976-04-29 1977-04-29 Heat exchanger
FR7712965A FR2349811A1 (en) 1976-04-29 1977-04-29 HEAT EXCHANGER
DE2719273A DE2719273C3 (en) 1976-04-29 1977-04-29 Heat exchanger
AT0307277A AT368622B (en) 1976-04-29 1977-04-29 HEAT EXCHANGER
IT2304077A IT1075648B (en) 1976-04-29 1977-04-29 Thermoplastics heat exchanger for heating water by solar energy - comprises two spaced collector tubes connected by profile with built-in pipes

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB17492/76A GB1574207A (en) 1976-04-29 1976-04-29 Heat exchanger

Publications (1)

Publication Number Publication Date
GB1574207A true GB1574207A (en) 1980-09-03

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB17492/76A Expired GB1574207A (en) 1976-04-29 1976-04-29 Heat exchanger

Country Status (2)

Country Link
GB (1) GB1574207A (en)
ZA (1) ZA772434B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2270376A (en) * 1992-09-07 1994-03-09 Collins Starnes Ass Fluid-heating solar panel
GB2290863A (en) * 1994-07-02 1996-01-10 David Donald Hayward Solar heater

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2270376A (en) * 1992-09-07 1994-03-09 Collins Starnes Ass Fluid-heating solar panel
US5411015A (en) * 1992-09-07 1995-05-02 Collins Starnes Associates Limited Radiation collectors
GB2270376B (en) * 1992-09-07 1996-07-10 Collins Starnes Ass Solar panels
GB2290863A (en) * 1994-07-02 1996-01-10 David Donald Hayward Solar heater

Also Published As

Publication number Publication date
ZA772434B (en) 1978-03-29

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