WO2009098444A2

WO2009098444A2 - Heat transfer apparatus

Info

Publication number: WO2009098444A2
Application number: PCT/GB2009/000289
Authority: WO
Inventors: Shane Mirza
Original assignee: Shane Mirza
Priority date: 2008-02-06
Filing date: 2009-02-03
Publication date: 2009-08-13
Also published as: GB2457245A8; GB0802155D0; WO2009098444A3; GB2457245A

Abstract

The present invention relates to heat transfer apparatus (1) for mounting on a vessel (5). The apparatus (1) comprises at least first and second sets of substantially planar fins (7,9). The fins (7) in the first set are angularly offset from and interconnect with the fins (9) in the second set. A plurality of the fins (7,9) is profiled to conform to the shape of the corresponding surface of the vessel (5).

Description

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HEAT TRANSFER APPARATUS

The present invention relates to heat transfer apparatus mountable on a vessel. More particularly, the present invention relates to heat transfer apparatus for a domestic radiator.

It is known from GB 1 ,099,687 to provide a series of surface extending fins for attachment to a tube. The fins are formed in series by folding a continuous strip of heat-conducting material to form a rectangular waveform with the fins in spaced parallel relationship. A pair of the series of fins can be mounted on opposite sides of the tube such that the inner ends of the fins of the two series overlap. The series are provided with tongues and notches so that the fins can interengage with each other. However, the waveform construction technique limits the range of applications for which the surface extending fins are suitable. Moreover, the appearance of the surface extending fins cannot readily be altered. US 4,648,443 discloses a heat exchanger with concertina-like fins formed from a continuous length of sheet material. The fins are welded to a tube such that they extend substantially perpendicular to a longitudinal axis of the tube. Again, the arrangement of the fins reduces the applications to which this technique may be applied. JP 3-140798 and JP 5-231795 disclose structures for supporting heat transfer tubes. The structures are formed from first and second sets of sheet members arranged perpendicular to each other to form a lattice. The heat transfer tubes are located in the spaces formed between the sheet members and the lattice extends substantially perpendicular to the heat transfer tubes. JP 3-140798 discloses an embodiment in which one set of the sheet members has a folded flange for supporting the heat transfer tubes. The support structures are not intended to function as heat transfer apparatus and would not be suitable for a radiator. At least in preferred embodiments, the present invention attempts to ameliorate or overcome at least of the problems associated with known heat exchangers.

Viewed from a first aspect, the present invention relates to heat transfer apparatus for mounting on a vessel, the apparatus comprising at least first and second sets of substantially planar fins, the fins in said first set being angularly offset from and interconnecting with the fins in said second set; wherein a plurality of said fins are profiled to conform to the shape of the corresponding surface of said vessel. The heat transfer apparatus may provide an extended surface mountable on the vessel to increase its surface area and provide improved heat transfer. The heat transfer apparatus may be used to heat or cool a fluid, such as air. The heat transfer apparatus may, for example, be used in a domestic radiator.

The interconnecting fins typically form a lattice structure and may define an array of cells. For example, the fins may define the sidewalls of the cells. At least one end of each cell is preferably open as this may allow fluid to exit the cells and promote airflow around the heat transfer apparatus. Preferably at least one open end of each cell is directed operatively upwardly. The cells may be open at the top and/or bottom. This is advantageous since air proximal the heat transfer apparatus may circulate freely.

Preferably, those fins profiled to conform to the shape of the vessel are in contact with a surface of the vessel when the heat transfer assembly is mounted on the vessel. The profiled fins preferably have at least one edge shaped to match the corresponding surface of the vessel. The fins in said first set and/or said second set may all be profiled to conform to the shape of the corresponding surface of said vessel. This is advantageous since the contact between the heat transfer apparatus and the vessel may be increased to promote conduction. When installed, the profiled edges of the fins preferably abut said vessel. The heat transfer apparatus may be attached to the vessel using mechanical fasteners, such as rivets, screws or bolts, but it is preferably soldered, welded or brazed in position.

The fins in the first set are preferably substantially parallel to each other; and/or the fins in the second set are preferably substantially parallel to each other. When the heat transfer apparatus is installed on the vessel, the fins in the first and second sets are preferably repeated in a lengthwise direction along the vessel. The angular offset between the fins in the first and second sets may be constant throughout the heat transfer apparatus. In certain circumstances, however, it may be desirable to vary the angular offset between the fins in the first and second sets. This varies the effective surface of the heat transfer apparatus and non-uniform heat transfer characteristics may be achieved. For example, the effective surface area may be increased by reducing the angular offset of the first and second fins relative to each other, thereby providing increased heat transfer. Conversely, the effective surface area may be decreased by increasing the angular offset of the first and second fins relative to each other, thereby reducing heat transfer in a particular region. In other words, the effective surface area may be increased by increasing the angle at which each fin is inclined relative to a longitudinal axis of the heat transfer apparatus; the effective surface area may be greatest when the fins are arranged - O ~ substantially perpendicular to the longitudinal axis. The effective surface area may be reduced by reducing the angle at which each fin is inclined relative to the longitudinal axis of the heat transfer apparatus; the effective surface area may be smallest when the fins are arranged substantially parallel to the longitudinal axis. The vessel may comprise a tube having a longitudinal axis. The fins in said first set and/or said second set may extend in planes substantially perpendicular to the longitudinal axis of the tube or they may be inclined at an angle to the longitudinal axis of the tube.

The fins in the first and/or second sets may extend substantially perpendicular to the surface of the vessel. Preferably, however, the fins in the first and/or second sets are inclined at an acute angle to the surface of the vessel.

When the heat transfer apparatus is installed ready for use, the fins are preferably inclined at an angle of less than or equal to 60° measured from the vertical. In arrangements in which the fins define an array of cells each having an open end, the fins are preferably operatively inclined upwardly towards an open end of said cells.

In addition to the first and second sets of fins, the heat transfer apparatus may comprise third and fourth sets of substantially planar fins. The fins in said third set are preferably angularly offset from and interconnect with the fins in said fourth set. The fins in the third set are preferably substantially parallel to each other; and/or the fins in the fourth set are preferably substantially parallel to each other.

The fins in the first set may abut the fins in the third set; and/or the fins in the second set may abut the fins in the fourth set. Alternatively, the fins in the first and second sets may be interleaved with the fins in the third and fourth sets. The fins in the first and third sets may be joined; and/or the fins in the second and fourth sets may be joined. When installed on a vessel, the sets of fins preferably extend around at least part of said vessel.

The heat transfer apparatus may comprise more than four sets of fins. The additional sets of fins are preferably provided in interconnecting pairs to provide a series of lattice structures.

The present invention further relates to heat transfer apparatus as described herein in combination with a vessel, the heat transfer apparatus being fixedly mounted on the vessel. The present invention also relates to a domestic radiator comprising a combination of a heat transfer apparatus and a vessel as described herein. Viewed from a further aspect, the present invention relates to an extended surface for mounting on a vessel, the extended surface comprising first and second sets of interconnecting fins; the fins in said first set being angularly offset from the fins in said second set to form a lattice structure; wherein each fin in said first and second sets is profiled to conform to the shape of the corresponding surface of said vessel.

Viewed from a yet further aspect, the present invention relates to an assembly comprising at least first and second sets of substantially planar fins, the fins in said first set being angularly offset from and interconnecting with the fins in said second set.

The term "interconnect" and derivatives thereof used herein may be replaced with the term "interengage" or "interweave". In certain embodiments, the fins may lock together and the term "interlocking" may be used to describe them.

Preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures in which:

Figure 1 shows a perspective view of a radiator incorporating a heat transfer assembly in accordance with a first embodiment of the present invention;

Figure 2 shows a plan view of the radiator according to the first embodiment;

Figure 3 shows a side view of the radiator according to the first embodiment; Figures 4a and 4b show plan views of the blanks for the interconnecting fins forming the heat transfer assembly according to the first embodiment;

Figure 5 shows a plan view of a modified version of the first embodiment of the heat transfer assembly according to the first embodiment;

Figure 6 shows a plan view of the radiator and heat transfer assembly according to a second embodiment of the present invention;

Figure 7 shows a side view of a radiator incorporating a heat transfer assembly in accordance with a second embodiment of the present invention;

Figures 8a and 8b show plan views of the blanks for the interconnecting fins forming the heat transfer assembly according to the second embodiment; Figure 9 shows a side view of a radiator incorporating a heat transfer assembly in accordance with a third embodiment of the present invention;

Figure 10 shows a plan view of the radiator and heat transfer assembly according to the third embodiment;

Figures 11a and 11b show plan views of the blanks for the interconnecting fins forming the heat transfer assembly according to the third embodiment Figures 12a and 12 b show a side view and an end view of a heat transfer assembly in accordance with a fourth embodiment of the present invention.

A radiator 1 in accordance with a first embodiment of the present invention is shown in Figure 1. The radiator 1 is intended to form part of a domestic central heating system.

The radiator 1 has a longitudinal axis X and comprises a heat transfer assembly 3 mounted on a sealed vessel 5. The heat transfer assembly 3 comprises a lattice structure 4 made up of a first set of like first fins 7 and a second set of like second fins 9. The first and second fins 7, 9 are adapted to interconnect or interengage with each other to form the lattice structure 4. The first and second fins 7, 9 are formed from sheet metal and are substantially planar.

The first fins 7 are all substantially the same as each other. Likewise, the second fins 9 are all substantially the same as each other. The first fins 7 in the first set are arranged substantially parallel to each other; and the second fins 9 in the second set are arranged substantially parallel to each other. The first and second fins 7, 9 are inclined at an angle relative to each other and interconnect with each other to form the lattice structure 4, as shown in Figures 2 and 3. The first fins 7 each interconnect with a plurality of said second fins 9. Likewise, the second fins 9 each interconnect with a plurality of said first fins 7. The lattice structure 4 forms an array of open cells. The interconnecting fins

7, 9 define the sidewalls of the cells which are open at the top and bottom. In use, the open cells allow the circulation of air around the heat transfer assembly 3.

The first fins 7 each have an upper edge 10 and a lower edge 11 ; and the second fins 9 each have an upper edge 12 and a lower edge 13. As shown in Figures 4a and 4b, a set of first slots 15 is formed in the upper edge 10 of each of the first fins 7; and a set of second slots 17 is formed in the lower edge 13 of each of the second fins 9. The first and second slots 15, 17 are co-operable with each other to enable the first and second fins 7, 9 to interconnect with each other. The upper edges 10, 12 of the first and second fins 7, 9 are convex and define the outer profile of the heat transfer assembly 3.

The lower edge of each of the first and second fins 7, 9 is profiled substantially to match the corresponding surface of the vessel 5 on which it is mounted. In the present embodiment, first and second rectangular recesses 19, 21 are formed in each of the first and second fins 7, 9. The profiling of the fins 7, 9 to match the corresponding shape of the vessel 5 provides a larger contact area between the heat transfer assembly 3 and the vessel 5 and thereby enables improved thermal conduction.

The vessel 5 according to the present embodiment comprises two tubes 23, 25 extending substantially parallel to each other. The tubes 23, 25 have a rectangular cross-section and are joined at each end to form an elongated O-shape in plan form. An inlet 27 and an outlet 29 are provided at first and second ends respectively of the vessel 5.

The heat transfer assembly 3 is assembled by interconnecting the first and second fins 7, 9 to form the lattice structure 4. The lattice structure 4 is then located on the vessel 5 as a unit such that the tubes 23, 25 are located in the first and second rectangular recesses 19 ,21. The lattice structure 3 is then secured in position. The fins 7, 9 may be secured using mechanical fasteners, such as rivets or bolts. Preferably, however, the fins 7, 9 are soldered, welded or brazed in position to permanently affix them to the vessel 5. In the present embodiment, the fins 7, 9 are arranged substantially perpendicular to the surface of the tubes 23, 25 making up the vessel 5.

The radiator 1 described herein is intended to form part of a central heating system, for example for installation in a domestic setting. In use, a heated liquid is pumped in conventional manner into the vessel 5 through the inlet 27. The liquid heats the vessel 5 and the heat transfer assembly 3 and then exits through the outlet 29. The heat transfer assembly 3 forms an extended surface which increases the surface area of the radiator 1 and improves transmission of heat to the surroundings.

The radiator 1 according to the first embodiment is intended to be installed with its longitudinal axis X extending substantially horizontally and the fins 7, 9 arranged in substantially vertical planes. In this orientation the cells formed by the fins 7, 9 advantageously open upwardly such that air heated by the heat transfer assembly 3 is free to exit through the tops of the cells. Moreover, air may be drawn into a plurality of the cells through their open bases.

The angular orientation of the fins 7, 9 relative to each other and to the longitudinal axis X may be varied along the length of the heat transfer assembly 3. This varies the effective surface of the heat transfer assembly 3 along its length and non-uniform heat transfer characteristics are achievable. For example, the effective surface area may be increased by reducing the angular offset of the fins 7, 9 to provide increased heat transfer in a particular region. Conversely, the effective surface area may be decreased by increasing the angular offset of the fins 7, 9 to provide reduced heat transfer in a particular region. A plan view of a modified version of the radiator 1 according to the first embodiment is illustrated in Figure 5. Again, the first fins 7 are all substantially the same shape; and the second fins 9 are all substantially the same shape. In this arrangement the angular offset of the first and second fins 7, 9 relative to each other is increased towards the middle of the heat transfer assembly 3 thereby reducing the effective surface area in this region. Conversely, the angular offset of the first and second fins 7, 9 relative to each other is reduced towards the ends of the heat transfer assembly 3 thereby increasing the effective surface area in this region. Thus, heat transfer is reduced towards the middle of the heat transfer assembly 3. Varying the angular orientation of the fins 7, 9 relative to each other may also alter the width of the heat transfer assembly 3, as shown in Figure 5. This technique may also be used to change the appearance of the radiator 1 to create decorative designs.

A radiator 101 comprising a heat transfer assembly 103 and a sealed vessel 105 in accordance with a second embodiment of the present invention is illustrated in Figures 6 and 7. This embodiment is similar to the first embodiment and like reference numerals have been used for like components albeit incremented by 100.

As for the first embodiment, the heat transfer assembly 103 comprises a lattice structure 104 made up of a first set of like first fins 107 and a second set of like second fins 109. The lattice structure 104 is again assembled by interconnecting the first and second fins 107, 109. As shown in Figure 6, the vessel 105 comprises a single tube 123 having a rectangular cross-section. The inlet 127 and outlet 129 are provided at opposite ends of the vessel 105 to provide a fluid pathway..

As shown in Figure 7, the first and second fins 107, 109 are canted so as to define an acute angle with the surface of the vessel 105. In the present embodiment, the first and second fins 107, 109 are inclined at an angle of 60° to the longitudinal axis X of the radiator 101. The radiator 101 is intended to be installed with the longitudinal axis X extending substantially vertically. In use, the fins 107, 109 are inclined at an angle of 60° to the vertical. The cells defined by the lattice structure 104 are each open at one end and the first and second fins 107, 109 are operatively inclined upwardly towards the open end of the cells. This arrangement facilitates the circulation of air around the radiator 101 , as illustrated by the arrows A.

The first and second fins 107, 109 are again formed from sheet metal and the blanks for forming them are illustrated in Figures 8a and 8b. The angular orientation of the fins 107, 109 is determined by the orientation of the first and second slots 115, - o -

117. Specifically, the first and second slots 115, 117 are inclined at an acute angle to a transverse axis Y of the first and second fins 107, 109 respectively.

In the present embodiment, a single rectangular recess 119 is formed in the lower edge 111 , 113 of the first and second fins 107, 109 respectively to accommodate the vessel 105. The fins 107, 109 may each be provided with one or more apertures to provide additional fluid pathways through the heat transfer assembly 103. These additional apertures may allow improved circulation around the radiator 101.

A radiator 201 comprising a heat transfer assembly 203 and a sealed vessel 205 in accordance with a third embodiment of the present invention is illustrated in Figures 9 and 10. This embodiment has features in common with the first embodiment and like reference numerals have been used for like components albeit incremented by 200.

As shown in Figure 9, the heat transfer assembly 203 comprises five lattice structures 204a-e provided around the outside of a cylindrical vessel 205. The lattice structures 204a-e are each constructed from first and second sets of interconnecting first and second fins 207, 209 in the same manner as the heat assemblies 3, 103 of the first and second embodiments described herein. The first fins 207 in each lattice structure 204a-e are all substantially the same and, likewise, the second fins 209 in each lattice structures 204a-e are all substantially the same.

The radiator 201 is intended to be installed vertically and the fins 207, 209 in each of the heat transfer assemblies 203a-e are canted such that, in use, they are inclined upwardly. In the present embodiment, the fins 207, 209 are inclined at 60° to the vertical when the radiator 201 is installed. As illustrated in Figure 10, the fins 207, 209 in each lattice structures 204a-e abut the corresponding fins 207, 209 in the adjacent lattice structures 204a-e. To provide additional rigidity to the structure, corresponding fins 207, 209 in adjacent lattice structures 204a-e may be soldered together. Alternatively, the fins 207, 209 in each lattice structure 204a-e may be interleaved with the fins 207, 209 in adjacent lattice structures 204a-e.

The blanks for the fins 207, 209 are shown in Figures 11a and 11b. A set of first slots 215 is formed in the upper edge 210 of each of the first fins 207; and a set of second slots 217 is formed in the lower edge 213 of each of the second fins 209. The lower edges 211 , 213 of the first and second fins 207, 209 are curved in the present embodiment to match the shape of the cylindrical vessel 205. The vessel 205 comprises an inlet tube 223 and an outlet tube 225 extending substantially parallel to a longitudinal axis X of the radiator 201. The inlet and outlet tubes 223, 225 are joined to form a pathway through which a heated fluid may be pumped. The provision of five lattice structures 204a-e further increases the surface area of the radiator 201 and may provide improved heat transfer around the outside of the vessel 205. The path followed by air heated by the radiator 201 is illustrated by the arrows A in Figure 9. The upwardly inclined orientation of the fins 207, 209 facilitates the movement of air heated by the radiator 201. A radiator fitting 301 comprising a heat transfer assembly 303 according to a fourth embodiment of the present invention is illustrated in Figures 12a and 12b. This embodiment has features in common with the first embodiment and like reference numerals have been used for like components albeit incremented by 300. The heat transfer assembly 303 comprises five (5) lattice structures 304a-e arranged around the circumference of a tubular vessel 305. Again, the lattice structures 304a-e each comprise first and second sets of interconnecting first and second fins 307, 309. The cross-section of the heat transfer assembly 303 is generally circular. However, in this embodiment, the profile of each of the first and second fins 307, 309 changes such that the outer profile of the lattice structure 304a- e is curved along the length of the heat transfer assembly 303.

It is envisaged that the radiator fitting 301 according to the fourth embodiment of the present invention could, for example, be fitted along a length of tube or as an end piece.

Although the heat transfer assemblies 3, 103, 203, 303 have been described herein with particular reference to domestic radiators 1 , 101 , 201 , 301 , it will be appreciated that they may be implemented in wider applications. A heat transfer assembly of the type described herein could be used as part of a heat exchanger for cooling a fluid, for example in a refrigeration unit or in an automotive application.

It will be appreciated that various changes and modifications may be made to the embodiments described herein without departing from the spirit and scope of the present invention.

Claims

CLAIMS:

1. Heat transfer apparatus for mounting on a vessel, the apparatus comprising at least first and second sets of substantially planar fins, the fins in said first set being angularly offset from and interconnecting with the fins in said second set; wherein a plurality of said fins are profiled to conform to the shape of the corresponding surface of said vessel.

2. Heat transfer apparatus as claimed in claim 1 , wherein each fin in said first set and/or said second set has an edge profiled to conform to the shape of the corresponding surface of said vessel.

3. Heat transfer apparatus as claimed in claim 1 or claim 2, wherein, in use, the profiled edges of the fins abut said vessel.

4. Heat transfer apparatus as claimed in any one of claims 1 , 2 or 3, wherein the fins in said first set and/or said second set extend substantially perpendicular to the surface of the vessel.

5. Heat transfer apparatus as claimed in any one of claims 1 , 2 or 3, wherein the fins in said first set and/or said second set extend at an acute angle relative to the surface of the vessel.

6. Heat transfer apparatus as claimed in any one of the preceding claims, wherein the fins in said first set are substantially parallel to each other; and/or the fins in said second set are substantially parallel to each other.

7. Heat transfer apparatus as claimed in any one of the preceding claims, wherein the fins define an array of cells each cell having an open end and the fins being operatively inclined upwardly towards an open end of said cells.

8. Heat transfer apparatus as claimed in any one of the preceding claims further comprising third and fourth sets of substantially planar fins, wherein the fins in said third set are angularly offset from and interconnect with the fins in said fourth set.

9. Heat transfer apparatus as claimed in claim 8, wherein the fins in the first set abut the fins in the third set; and the fins in the second set abut the fins in the fourth set.

10. Heat transfer apparatus as claimed in claim 8, wherein the fins in the first and second sets are interleaved between the fins in the third and fourth sets.

11. Heat transfer apparatus as claimed in any one of the preceding claims, wherein, in use, said at least first and second sets of substantially planar fins extend around said vessel.

12. Heat transfer apparatus as claimed in any one of the preceding claims in combination with a vessel, the heat transfer apparatus being fixedly mounted on the vessel.

13. A domestic radiator comprising a combination of a heat transfer apparatus and a vessel as claimed in claim 12.

14. An extended surface for mounting on a vessel, the extended surface comprising first and second sets of interconnecting fins; the fins in said first set being angularly offset from the fins in said second set to form a lattice structure; wherein each fin in said first and second sets is profiled to conform to the shape of the corresponding surface of said vessel.

15. An assembly comprising at least first and second sets of substantially planar fins, the fins in said first set being angularly offset from and interconnecting with the fins in said second set.

16. Heat transfer apparatus substantially as herein described with reference to the accompanying Figures.