GB2375164A

GB2375164A - Heat exchanger system

Info

Publication number: GB2375164A
Application number: GB0111153A
Authority: GB
Inventors: Gwyn Thomas
Original assignee: Llanelli Radiators Ltd
Current assignee: Marelli Automotive Systems UK Ltd
Priority date: 2001-05-04
Filing date: 2001-05-04
Publication date: 2002-11-06
Anticipated expiration: 2021-05-04
Also published as: GB0111153D0; GB2409511B; GB2409511A; GB2375164B; GB0504941D0; WO2002090856A1; EP1384038A1

Abstract

A heat exchanger system (particularly for automotive use) having a bank of spaced heat exchanger tubes and a matrix 1 for directing a flow of heat exchange fluid through the heat exchanger system externally of the spaced tubes, the matrix including spacing strips (fig 3, 9), respective strips including spanning portions 2 spacing respective tubes in the bank, and receiving portions 4A, 4B for receiving respective tubes. The tube bank and strip matrix are preferably fused together to form a unitary heat exchanger unit. The heat exchanger is economical to construct and provides improved technical performance.

Description

Heat Exchanger System The present invention relates to heat exchanger systems, and in particular to heat exchanger systems for automotive use.

I Heat exchanger systems are known comprising arrays of tubes for carrying a first heat exchange fluid between spaced headers. A fin matrix (typically airside for vehicle radiators or condensers) forms a path for a second heat exchange fluid (for example air). Typically the fin matrix comprises elongate serpentine metallic strips extending in the longitudinal direction of the tubes and in thermal bonded contact with adjacent spaced tubes. In certain embodiments the tubes and fin airway strips are of aluminium material clad with a brazing alloy. The tubes and airway matrix are assembled, secured by jigging clamps and brazed in a one shot brazing process.

An improved heat exchanger system has now been devised which is economical to construct, versatile for different applications and provides good technical performance.

According to a first aspect, the present invention provides a heat exchanger system comprising: a bank of heat exchanger tubes, adjacent tubes in the bank being spaced; a matrix for directing flow of a heat exchange fluid through the heat exchanger system externally of the

tubes, the matrix comprising a plurality of spaced spacing strips, respective strips including: spanning portions spacing respective tubes in the bank; and,

, a plurality of receiving portions for receiving a respective plurality tubes in the bank of tubes.

The strips are preferably arranged spaced face adjacent face, and desirably orientated transversely to the tubes.

The tube bank and strip matrix are preferably fused together to form a unitary heat exchanger unit. The system is preferably of brazed aluminium construction, the tubes and strips beneficially comprising aluminium material components (typically clad with a brazing alloy). The tube bank and strip matrix are typically fused together in an aluminium brazing process following assembly.

The receiving portions preferably comprise void portions shaped and dimensioned to accommodate the thickness of a respective tube. The void portions preferably comprise slots, the slots beneficially intersecting an edge of the respective spacing strip. The slots intersect opposed edges of the respective strip. The slots beneficially have respective closed ends opposed to the slot open end intersecting the strip edge.

The spacing strips are preferably laid up to be spaced from

one another and face to face spaced adjacent one another. For optimum performance, the spacing between adjacent strips is preferably substantially in the range 1mm-2mm.

The tubes in the bank are for optimum performance preferably spaced from adjacent tubes by a spacing distance , substantially within the range 4mm-12mm.

The above preferred ranges give a preferred hydraulic diameter for the heat exchanger design substantially in the range 1.5 to 3.5.

The system is effectively self jigging for the fusing/brazing process. This is because the tubes are retained securely in the matched up receiving portions of the strips such that clamping is not required. This gives significant cost reductions. Typically 30% or more of the heat supplied in an aluminium brazing furnace is used merely in wasteful heating of the securing jigging clamps.

The arrangement also provides for highly automated assembly for bonding. The tubes may be inserted simultaneously through the open slot ends in a direction transverse to the longitudinal direction of the tubes.

One or mor tab portions are preferably provided proximate the edge of a respective slot, the respective tab portion beneficially extending generally transversely to the major surface of the strip. The tab portions serve as spacers to contact and provide consistent spacing between adjacent strips in the matrix.

The respective tab portions are preferably provided proximate spaced opposed edges of a respective slot. The transverse extent of the tab portion is substantially of 50% or greater of the width of the slot (more preferably

of 70% or greater of the width of the slot, most preferably substantially equal to the width of the slot).

I The respective tab portions are preferably formed from material comprising the strip, the tab being turned outwardly to leave a void defining the slot. Tabs are preferably formed from adjacent portions of material turned outwardly to leave a void defining the slot, the adjacent tab forming portions preferably being connected at opposed edges of the slot.

In addition to spacing, the tabs may also provide a greater surface area for bonding (for example by brazing) to the external wall of the tube.

Desirably, the free outer edge of a respective tab includes a seat portion extending transversely to the general surface of the respective tab. The seat portion of a tab of a respective slot in a first strip beneficially rests against the edge material (underside) of a respective slot in a second adjacently laying strip in the matrix. The seat portion avoids the tab of one strip inadvertently extending into a matched up slot of the adjacent laying strip.

In one embodiment, the receiving portions of the spacing strips are configured such that, when receiving tubes,

adjacent tubes overlap widthwise preferably by substantially 50% or greater. In this embodiment the spanning portions are preferably provided with boundary layer disruptive formations such as louvres, slits, slots or the like. This arrangement effectively provides for a

single bank of tubes, adjacent tubes being respectively , staggered or displaced depending upon the degree of widthwise overlap of adjacent tubes. Such a staggered tube configuration may provide improved heat transfer characteristics per unit core depth due to improved airflow adhesion to the tubes (for example where the matrix strips define airways).

In an alternative embodiment, the heat exchanger system may comprise : a first heat exchanger arrangement comprising a first bank of heat exchanger tubes, adjacent tubes having spaces therebetween; a second heat exchanger arrangement comprising a second bank of heat exchanger tubes, adjacent tubes having spaces therebetween, the first and second banks of tubes being substantially side by side the tubes extending in a common general direction; respective spacing strips comprising the matrix including a first row of spaced tube receiving slots intersecting a first edge of the strip and a second row of spaced tube receiving slots intersecting a second edge of the strip.

The first row of spaced tube receiving slots in a respective strip preferably receives tubes from a respective one of the first and second banks of tubes, the second row of spaced tube receiving slots in a respective strip receiving tubes from the other respective one of the first and second banks of tubes.

The arrangement defined enables the system to be used as a dual or unified heat exchanger such as for example a unified condenser radiator as described in general terms in EP-A-0367078.

In one embodiment the tubes in the first tube bank may advantageously be orientated in side by side, in-line, configuration with respective tubes in the second tube bank. In this embodiment the slots in the first row are in match-up relationship with slots in the second row.

Tubes in the first tube bank are orientated in offset/staggered relationship with respective tubes in the second tube bank. In this embodiment the slots in the first row are in correspondingly offset/staggered relationship with slots in the second row. Such a staggered tube configuration may provide improved heat transfer characteristics per unit core depth due to improved airflow adhesion to the tubes (for example where the matrix strips define airways) and also managed airflow resulting from venturi effect generated between the two tube banks.

Respective strips in the matrix preferably include one or

more (preferably a series of) zones of reduced thermal conductivity inhibiting heat transfer via the strip between the banks of tubes. Such a zone of reduced conductivity may comprise an aperture (such as a slot or slit) in the strip positioned intermediate respective slots in the first

and second rows. Additionally or alternatively, such a , zone of reduced conductivity may comprise a gauge reduction portion (such as a groove, channel or notch) in the strip positioned intermediate respective slots in the first and second rows.

In certain embodiments the heat exchanger system may comprise: a pair of headers at opposed ends of the first bank of tubes and communicating with opposed respective ends of the tubes in the respective bank; and, a pair of headers at opposed ends of the second bank of tubes and communicating with opposed respective ends of the tubes in the respective bank.

The tubes in the first bank may contain a heat exchange fluid associated with a first heat exchange circuit, the heat exchange tubes in the second bank containing a heat exchange fluid associated with a second heat exchange circuit. one of the first and second heat exchanger arrangements may beneficially comprise a condenser of a refrigerant circuit of an vehicle air conditioning arrangement, the other of

the first and second heat exchanger comprising a part of the engine coolant circuit.

According to a further aspect, the present invention provides a fin strip for spacing tubes in a heat exchanger system, the fin strip including:

, spanning portions spacing respective tubes in the bank; and, a plurality of receiving portions for receiving a respective plurality tubes in the bank of tubes.

Preferred features and advantages of the fin strip are described above with respect to the first aspect of the invention.

According to a further aspect, the invention provides a method of manufacturing a heat exchanger system comprising: setting a fin matrix comprising a plurality of fin strips as herein defined arranged in face adjacent face spaced configuration such that tube receiving slots in respective adjacent strips are in match-up relationship; mating individual tubes with respective matched-up slots in a plurality of the fin strips in the matrix to form a bank of spaced tubes; bonding the fin matrix and tube bank arrangement in a

heat bonding process stage to form a unitary heat exchanger component.

The slots in the strips beneficially intersect a respective longitudinal edge of the strips, the tubes preferably being

mated by insertion in the direction of the tube width into , the matched-up slots through the mouths of respective slots.

The slots in the strips may intersect two opposed longitudinally running edges of a respective strip, in which case the tubes are preferably mated by insertion in the direction of the tube width into the matched-up slots through the mouths of respective slots in both longitudinally running edges of the strips (preferably simultaneously).

The strips and tubes are preferably of aluminium material, the tubes and strips being bonded in a one shot brazing process in which a brazed connection is formed between tubes and strips at the interface between the slots and the outer tube walls.

According to a still further aspect the invention provides a heat exchanger system including: a first bank of heat exchanger tubes, adjacent tubes having spaces therebetween; a second bank of heat exchanger tubes, adjacent tubes having spaces therebetween, the first and second banks

of tubes being substantially side by side, the tubes extending in a common general direction, wherein tubes in the first tube bank are orientated in offset/staggered relationship with respective tubes in the second tube bank.

The invention will now be further described in specific embodiments by way of example only and with reference to the accompanying drawings in which: Figure 1 is a plan view of an airway matrix strip according to the invention for use in a heat exchanger system in accordance with the invention; Figure 2 is a more detailed view of the part of strip of Figure 1; Figure 3 is a section along A-A in Figure 2; Figure 4 is a section along B-B in Figure 2; Figure 5 is a perspective view of a portion of the strip of Figures 1 to 4 showing the upstanding tabs; Figure 6 is a plan view of the portion of the strip of Figure 5 prior to folding out the tabs; Figure 7A and 7B are plan and side views respectively of a strip in accordance with the invention; Figures 8A, 8B and 9A, 9B are plan and side views

respectively of alternative configurations of airway matrix strips according to the invention for use in heat exchanger systems in accordance with the invention; Figure 10 is a plan view of a further alternative configuration of airway matrix strip ;, and Figure 11 is a schematic perspective view of a part of a heat exchanger system according to the invention.

Referring to the drawing and initially to Figure 1, there is shown an airway matrix fin strip 1 for use in a heat exchanger system. The airway fin is formed of a thin strip of aluminium material clad with an aluminium brazing alloy.

The strip is typically of gauge 0. 12mm-0. 05mm. In use the fins are set up overlaying one adjacent the other, being spaced by means of tabs 9 upstanding from the general surface of the respective strips 1 as will be described hereinafter below. Typically the fins are built up face adjacent face spaced by tabs 9 in stacks of two to eight hundred deep. The tabs 9 are shaped dimension to provide a fin pitched spacing of, typically, Imm - 2mm.

Each fin strip 1 comprises a spanning portion 2 (provided with an airflow slit louvered portion 3) and, either side of respective spanning portions 2, a series of slots 4A, 4B. In the embodiment shown in Figure 1 slots 4A have open ends intersecting a first longitudinal edge of the strip 1 alternating with slots 4B having open ends interconnecting with the other longitudinally running edge of strip 1.

Slots 4A, 4B are shaped dimension to receive (extending transversely thereto i. e. into the paper in Figure 1) heat exchange fluid tubes (not shown) to be positioned in a bank spaced from one another by spanning portions 2 and extending in the same longitudinal tube direction.

Typically the tubes are positioned in, a batch adjacent the relevant slots 4A, 4B and introduced simultaneously by sideways movement (directions of arrow A and arrow B) to be received in the array formed by the stack of airways 1.

The tubes are generally clad with aluminium brazing alloy and the design is such that when the tubes are received in respective slots 4A, 4B in the stack of strips 1, the arrangement is self supporting (i. e. no further jigging or clamping is required). The assembly will then be introduced into the brazing furnace for brazing. Typically header tanks (not shown) are mounted to the opposed open ends of the tubes prior to brazing. Figure 11 shows how tubes 101 and fin strips 1 are laid up.

A significant advantage of the present invention is that the self-j igging construction provides increased productivity. In other designs, jigging is required, and typically the jigging clamps may use up 30 percent of the furnace power in heating.

One important aspect of the invention is that spacing of the strips 1 in the stack is provided by tabs 9. Tabs 9 are positioned around the periphery of respective slots 4A, 4B and standing proud of the surface of the strip 1. The tabs 9 are shown most conveniently in Figures 3,4 and 5. Each tab 9 includes a dart or seat formation 8 extending

transversely to the general surface of tab 9. The dart or seat 8 ensures that the next adjacent strip 1 in the stack rests conveniently upon the outwardly splayed dart or seat 8 at the uppermost position of the relevant tabs 9. This arrangement results in consistent spacing of the strips 1 in the stack.

, If the seats or darts 8 are not present (making the upper edge of tabs 9 straight), there is a tendency for the upper edge of the tabs 9 to extend into and through the matched up slot 4A, 4B of the overlaying strip 1 in the stack.

As shown in Figure 6, an important feature of the tabs 9 is that they have, when oriented in an upstanding direction, a height dimension greater than 50 percent of the width of the slot. As shown clearly in Figure 6, the tabs are formed from the material of the strip such than, when deformed to extend transversely to the general surface of the strip 1, void portions defining the slot remain. In order to ensure that adjacent strips in the stack are sufficiently spaced, it is important that the height dimension is 50 percent or greater of the width of slots 4A, 4B.

The embodiments shown in Figures 1A to 7A result in a heat exchanger having tubes in a single bank substantially in parallel, but adjacent tubes having a slightly staggered overlap relationship. Typically, for producing a heat exchanger having effectively a single bank of tubes (Figures 1A to 7A and Figure 11) the widthwise overlap of adjacent tubes is 50% or greater. The louvred tube spacing

portions 3 of strip 1 are positioned intermediate adjacent tubes.

Using the embodiments shown in Figures 8 to 10, the resulting heat exchanger system has tubes in two side-byside banks. In such arrangements, the tubes in the separate banks may be connected to separate headers to provide, for example, separate side-by-side heat exchanger units such as units currently becoming in vogue, for example, unified or combined condenser radiators for vehicles. A general arrangement for such a unified or combined heat exchanger is disclosed for example in EP-A- 0367078.

In the arrangements shown in Figures 8A and 8B, separate tube banks are defined by rows of slots 4A, 4B respectively. In addition to the slots 4A, 4B holding tubes in separate spaced banks, the tubes are retained in slots 4A, 4B in a respectively staggered or offset relationship between the two banks of tubes. Such staggered tube configuration provides improved heat transfer performance with respect to equivalent heat exchanger core depth for matched up or aligned tubes in respective banks. This is due to the improved airflow adhesion to the tubes for the staggered tube banks and the managed airflow resulting from the venturi effect generated between the two tube banks. For such duel core or combined heat exchanger arrangements, it is important to minimise the heat transfer by the airway matrix fin strips between the tubes in the adjacent banks defining the respective cores. To this end, it is typical to provide zones of

reduced conduction between the tubes in the adjacent banks. In the embodiment shown in Figure 8A, this is achieve by the tubes being staggered and the louvres defining slits in the conduction path between the slots 4A, 4B.

In the embodiment shown in Figure 9, the conduction path is reduced by means of providing apertures 11 in the path between the spaced banks of slots 4A, 4B in the respective strip 1. As further alternative gauge reduction portions (such as grooves, notches, slits, channels or the like) may be provided intermediately between slots 4A, 4B receiving the tubes in respective spaced banks.

In the embodiment shown in Figure 10, the respective slots 4A, 4B defining each bank of tubes are substantially parallel to one another and matched up one to one. In this embodiment the reduced heat transfer path between the tube holding slot banks 4A, 4B are provided, again, by apertures

11.

Referring to Figure 11, for all embodiments, optimum heat exchanger performance has been found to be achieved, with

a strip 1 spacing (x) substantially in the range 1mm-2mm and a tube spacing (y) substantially in the range 4mm- 12mm. The preferred hydraulic diameter for the systems of the invention are therefore preferably substantially in the range 1.5 to 3.5.

The heat exchanger system according to the invention combines ease of construction and economic advantage in terms of constructions costs together with versatility of

design for use in differing applications. Benefits are envisaged in multi-core heat exchanger designs having spaced banks of tubes, in particular, in such arrangements where the tubes in respective banks can be offset or staggered with respect to one another. The present invention enables such heat exchanger, systems to be readily and conveniently achieved.

Claims

Claims: 1. A heat exchanger system comprising: a bank of heat exchanger tubes, adjacent tubes in the bank being spaced; a matrix for directing flow of a heat exchange fluid through the heat exchanger system externally of the tubes, the matrix comprising a plurality of spaced spacing strips, respective strips including: spanning portions spacing respective tubes in the bank; and, a plurality of receiving portions for receiving a respective plurality tubes in the bank of tubes.
2. A heat exchanger system according to claim 1, wherein the spacing between adjacent tubes is substantially in the range 4mm-12mm.
3. A heat exchanger system according to claim 1 or claim 2, wherein the spacing between adjacent strips is substantially in the range lmm - 2mm.
4. A heat exchanger system according to any of claims 1 to 3, having a hydraulic diameter substantially in the range 1.5 and 3.5.

<Desc/Clms Page number 18>
5. A heat exchanger system according to any preceding claim, wherein the tube bank and strip matrix are fused together to form a unitary heat exchanger unit.
6. A heat exchanger system according to any preceding claim, wherein the system is of brazed aluminium construction, the tubes and strips comprising aluminium material components, the tube bank and strip matrix being fused together in an aluminium brazing process.
7. A heat exchanger system according to any preceding claim, wherein the receiving portions comprise void portions shaped and dimensioned to accommodate the thickness of a respective tube.
8. A heat exchanger system according to claim 7, wherein the void portions comprise slots, the slots intersecting an edge of the respective spacing strip.
9. A heat exchanger system according to claim 8, wherein slots intersect opposed edges of the respective strip.
10. A heat exchanger system according to claim 8 or claim 6, wherein the slots have respective closed ends opposed to the slot end intersecting the strip edge.
11. A heat exchanger system according to any of claims 8 to 10, wherein one or mor tab portions are provided proximate the edge of a respective slot, the

<Desc/Clms Page number 19>

respective tab portion extending generally transversely to the major surface of the strip.
12. A heat exchanger system according to claim 11, wherein the respective tab portions are provided proximate spaced opposed edges of a respective slot.
13. A heat exchanger system according to claim 11 or claim 12, wherein the transverse extent of the tab portion is substantially at or greater than 50% of the width of the slot.
14. A heat exchanger system according to claim 13, wherein the transverse extent of the tab portion is substantially at or greater than 70% of the width of the slot.
15. A heat exchanger system according to claim 14, wherein the transverse extent of the tab portion is substantially equal to the width of the slot.
16. A heat exchanger system according to any of claims 11 to 15, wherein the respective tab portion is formed from material comprising the strip, the tab being turned outwardly to leave a void defining the slot.
17. A heat exchanger system according to claim 13, wherein tabs are formed from adjacent portions of material turned outwardly to leave a void defining the slot, the adjacent tab forming portions being connected at opposed edges of the slot.

<Desc/Clms Page number 20>
18. A heat exchanger system according to any of claims 11 to 17, wherein the free outer edge of a respective tab includes a seat portion extending transversely to the

general surface of the respective tab.

I
19. A heat exchanger system according to claim 18, wherein the seat portion of a tab of a respective slot in a first strip rests against the edge material of a respective slot in a second adjacently laying strip in the matrix.
20. A heat exchanger system according to any preceding claim comprising: a first heat exchanger arrangement comprising a first bank of heat exchanger tubes, adjacent tubes having spaces therebetween; a second heat exchanger arrangement comprising a second bank of heat exchanger tubes, adjacent tubes having spaces therebetween, the first and second banks of tubes being substantially side by side the tubes extending in a common general direction; respective spacing strips comprising the matrix including a first row of spaced tube receiving slots intersecting a first edge of the strip and a second row of spaced tube receiving slots intersecting a second edge of the strip.

<Desc/Clms Page number 21>
21. A heat exchanger system according to claim 20, wherein the first row of spaced tube receiving slots in a respective strip receives tubes from a respective one of the first and second banks of tubes, the second row of spaced tube receiving slots in a respective strip receiving tubes from the other respective one of the first and second banks of tubes.
22. A heat exchanger system according to claim 20 or claim 21, wherein the tubes in the first tube bank are orientated in side by side, in-line, configuration with respective tubes in the second tube bank.
23. A heat exchanger system according to claim 22, wherein the slots in the first row are in match-up relationship with slots in the second row.
24. A heat exchanger system according to claim 20 or claim 21, wherein tubes in the first tube bank are orientated in offset/staggered relationship with respective tubes in the second tube bank.
25. A heat exchanger system according to claim 24, wherein the slots in the first row are in offset/staggered relationship with slots in the second row.
26. A heat exchanger system according to any of claims 20 to 25, wherein respective strips in the matrix include one or more zones of reduced thermal conductivity inhibiting heat transfer via the strip between the banks of tubes.

<Desc/Clms Page number 22>
27. A heat exchanger system according to claim 26, wherein respective strips in the matrix include a series of zones of reduced thermal conductivity inhibiting heat

transfer via the strip between the banks of tubes.

,
28. A heat exchanger system according to claim 26 or claim 27, wherein a zone of reduced conductivity comprises an aperture (such as one or more slots or slits) in the strip positioned intermediate respective slots in the first and second rows.
29. A heat exchanger system according to claim 26 or claim 27, wherein a zone of reduced conductivity comprises a gauge reduction portion (such as one or more grooves, channels or notches) in the strip positioned intermediate respective slots in the first and second rows.
30. A heat exchanger system according to any of claims 20 to 29 including: a pair of headers at opposed ends of the first bank of tubes and communicating with opposed respective ends of the tubes in the respective bank; and, a pair of headers at opposed ends of the second bank of tubes and communicating with opposed respective ends of the tubes in the respective bank.

<Desc/Clms Page number 23>
31. A heat exchanger according to any of claims 20 to 30, wherein the tubes in the first bank contain a heat exchange fluid associated with a first heat exchange circuit, the heat exchange tubes in the second bank containing a heat exchange fluid associated with a second heat exchange circuit.
32. A heat exchanger system according to claim 31, wherein one of the first and second heat exchanger arrangements comprises a condenser of a refrigerant circuit of an vehicle air conditioning arrangement, the other of the first and second heat exchanger comprising a part of the engine coolant circuit.
33. A fin strip for spacing tubes in a heat exchanger system, the fin strip including: spanning portions spacing respective tubes in the bank; and, a plurality of receiving portions for receiving a respective plurality tubes in the bank of tubes.
34. A fin strip according to claim 33, wherein the receiving portions comprise void portions shaped and dimensioned to accommodate the thickness of a respective tube.
35. A fin strip according to claim 34, wherein the void portions comprise slots, the slots intersecting an

<Desc/Clms Page number 24>

edge of the respective spacing strip.
36. A fin strip according to claim 35, wherein slots intersect opposed edges of the respective strip.
37. A fin strip according to claim 35 or claim 36, wherein the slots have respective closed ends opposed to the slot end intersecting the strip edge.
38. A fin strip according to any of claims 35 to 37, wherein one or mor tab portions are provided proximate the edge of a respective slot, the respective tab portion extending generally transversely to the major surface of the strip.
39. A fin strip according to claim 38, wherein the respective tab portions are provided proximate spaced opposed edges of a respective slot.
40. A fin strip according to claim 38 or claim 39, wherein the transverse extent of the tab portion is substantially at or greater than 50% of the width of the slot.
41. A fin strip according to claim 40, wherein the transverse extent of the tab portion is substantially at or greater than 70% of the width of the slot.
42. A fin strip according to claim 41, wherein the transverse extent of the tab portion is substantially equal tb the width of the slot.

<Desc/Clms Page number 25>
43. A fin strip according to any of claims 38 to 42, wherein the respective tab portion is formed from material comprising the strip, the tab being turned

outwardly to leave a void defining the slot.

,
44. A fin strip according to claim 43, wherein tabs are formed from adjacent portions of material turned outwardly to leave a void defining the slot, the adjacent tab forming portions being connected at opposed edges of the slot.
45. A fin strip according to any of claims 38 to 44, wherein the free outer edge of a respective tab includes a seat portion extending transversely to the general surface of the respective tab.
46. A fin strip according to claim 45, wherein the seat portion of a tab of a respective slot in a first strip rests against the edge material of a respective slot in a second adjacently laying strip in the matrix.
47. A fin strip according to any of claims 33 to 46, including a first row of spaced tube receiving slots intersecting a first edge of the strip and a second row of spaced tube receiving slots intersecting a second edge of the strip.
48. A fin strip according to claim 47, wherein the slots in the first row are in match-up relationship with slots in the second row.

<Desc/Clms Page number 26>
49. A fin strip according to claim 47, wherein the slots in the first row are in offset/staggered relationship with slots in the second row.
50. A fin strip according to any pf claims 47 to 49, including one or more zones of reduced thermal conductivity inhibiting heat transfer via the strip between the rows of slots.
51. A fin strip according to claim 50, including a series of zones of reduced thermal conductivity inhibiting heat transfer via the strip between the rows of slots.
52. A fin strip according to claim 50 or claim 51, wherein a zone of reduced conductivity comprises an aperture (such as one or more slots or slits) in the strip positioned intermediate respective slots in the first and second rows.
53. A fin strip according to claim 50 or claim 51, wherein a zone of reduced conductivity comprises a gauge reduction portion (such as one or more grooves, channels or notches) in the strip positioned intermediate respective slots in the first and second rows.
54. A method of manufacturing a heat exchanger system comprising: setting a fin matrix comprising a plurality of fin

<Desc/Clms Page number 27>

strips according to any of claims 30 to 50 arranged in face adjacent face spaced configuration such that tube receiving slots in respective adjacent strips are in match-up relationship ;

mating individual tubes with respective matched-up i slots in a plurality of the fin strips in the matrix to form a bank of spaced tubes; bonding the fin matrix and tube bank arrangement in a heat bonding process stage to form a unitary heat exchanger component.
55. A method according to claim 54, wherein the slots in the strips intersect a respective longitudinal edge of the strips, the tubes being mated by insertion in the direction of the tube width into the matched-up slots through the mouths of respective slots.
56. A method according to claim 54 or 55, wherein the slots in the strips intersect two opposed longitudinally running edges of a respective strip, the tubes being mated by insertion in the direction of the tube width into the matched-up slots through the mouths of respective slots in both longitudinally running edges of the strips substantially simultaneously.
57. A method according to any of claims 54 to 56, wherein the strips and tubes are of aluminium material, the tubes and strips being bonded in a one shot brazing

<Desc/Clms Page number 28>

process in which a brazed connection is formed between tubes and strips in the region of the interface between the slots and the outer tube walls.
58. A heat exchanger system including : , a first bank of heat exchanger tubes, adjacent tubes having spaces therebetween; a second bank of heat exchanger tubes, adjacent tubes having spaces therebetween, the first and second banks of tubes being substantially side by side, the tubes extending in a common general direction, wherein tubes in the first tube bank are orientated in offset/staggered relationship with respective tubes in the second tube bank.