WO2002068890A1

WO2002068890A1 - Heat exchanger system

Info

Publication number: WO2002068890A1
Application number: PCT/GB2002/000778
Authority: WO
Inventors: John Smith; Gwyn Thomas
Original assignee: Llanelli Radiators Limited
Priority date: 2001-02-24
Filing date: 2002-02-22
Publication date: 2002-09-06
Also published as: GB2372560A; GB0104582D0

Abstract

A unified heat exchanger (1) such as a combined condenser/radiator has a first bank of heat exchanger tubes (9) and a second heat exchanger arrangement comprising a second bank of heat exchanger tubes (6), the first (9) and second (6) banks of tubes being substantially side by side. A matrix for directing flow of a heat exchange fluid through the heat exchanger system (1) externally of the tubes, the matrix comprising a flow directing strip (10) extending longitudinally between adjacent tubes in a respective bank (6,9) and spanning to extend transversely across adjacent banks (6,9). The flow directing strip (10) has a gauge reduction portion (12) inhibiting heat transfer via the strip (10) between the banks of tubes (6,9).

Description

Heat Exchanger System

The present invention relates to a heat exchanger system and in particular to a heat exchanger system suitable for vehicular use.

So called unified heat exchangers are known which comprise an assembly of plural heat exchangers typically assembled and joined face adjacent face, each for effecting a heat transfer exchange between different heat exchange circuits. A typical unitary assembly is a combined (or unified) condenser radiator which comprises a vehicle coolant circuit radiator arrangement mounted face adjacent face with a condenser arrangement for a vehicle refrigerant air conditioning circuit. Such an arrangement is shown for example in EP-A-0367078. In the arrangement shown in EP-A- 0367078 the problem of heat transfer across the airway matrix fin strips between the tubes in the radiator and condenser is acknowledged. The temperature differential between the working fluid in the tubes of the respective condenser and radiator under nominal operating conditions results in adverse heat transfer between the condenser and radiator transversely along the fin airway strips. In EP- A-0367078 a solution is proposed by providing slits in the airway fins intermediate the tube bank cores of the adjacent heat exchanger arrangements. Other examples of prior art arrangements employing slits, apertures or other cut-out portions are disclosed in, for example, EP-A- 0866298, GB-A-2356040 , WO-A-99/30098 and EP-A-431917. An alternative and improved solution has now been devised.

According to a first aspect, the present invention provides a heat exchanger system 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;

a matrix for directing flow of a heat exchange fluid through the heat exchanger system externally of the tubes, the matrix comprising a flow directing strip extending longitudinally between adjacent tubes in a respective bank and spanning to extend transversely across adjacent banks, the flow directing strip having a gauge reduction portion inhibiting heat transfer via the strip between the banks of tubes.

The gauge reduction portion provides a restricted heat transfer path between the banks of tubes but maintains a good structurally integral link or bridge between the banks of tubes. The gauge of the strip material is a term commonly referred to in the art and defines the thickness of the strip material (dimension Y in Figure 3) . The gauge reduction portion of the strip provides a reduced or narrow gauge thickness portion (dimension y in Figure 3) providing a restricted heat transfer path.

The gauge reduction portion may comprise a work hardened/plastically deformed portion which may be formed by stretching, mechanical deformation or otherwise by material displacement. Material deformation may alternatively be effected in ways such as notching grooving or otherwise, resulting in little or no stretching or work hardening.

The gauge reduction portion may comprise or include a gauge reduction formation running along the strip in the longitudinal direction.

The gauge reduction portion may comprise or include one or more notches, grooves or channel formations formed at a first surface of the strip.

The gauge reduction portion may comprise a notch, groove or channel formation formed at a first surface of the strip and a complementary configured notch, groove or channel formation formed at a second surface of the strip, a restricted waist portion being thereby defined.

The gauge reduction portion may include material stretched (plastically deformed) in the direction of spacing of the banks of tubes .

The strip is preferably formed in a serpentine configuration the gauge reduction portion preferably extending longitudinally along a median line along the serpentine formed strip.

The gauge reduction portion beneficially extends longitudinally at a position intermediate the spaced banks of tubes .

The gauge reduction portion provides a solid bridge between spaced portions of the strip interleaving the tubes in respective banks.

The gauge reduction portion has a minimum material thickness reduced by 50% or more compared to the standard gauge of the strip portions interleaving the tubes in the banks. More preferably the gauge reduction is 60% or above, more preferably 70% or above most preferably 80% or above, compared to the standard strip gauge . The thinner the gauge of the gauge reduction portion the better (in order to minimise the heat transfer) providing the integrity of the bridge across the tube banks is sufficiently maintained.

The gauge reduction portion may comprise or include a plurality of gauge reduction formations running in the direction of the tubes and spaced from each other in side by side relationship.

The heat exchanger system according to the invention is preferably substantially of brazed aluminium construction.

In thermal processes such as brazing, the gauge reduction portion may 'burn through' to provide a hole or aperture through the gauge or width of the strip. Such a burn through aperture provides a good barrier to thermal heat transfer.

The heat exchanger system preferably includes :

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 preferably contain a heat exchange fluid associated with a first heat exchange circuit, the heat exchange tubes in the second bank beneficially containing a heat exchange fluid associated with a second heat exchange circuit .

Beneficially 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 .

According to a further aspect the invention provides an airway fin matrix strip for a heat exchanger system, comprising an elongate strip of material formed to have one or more longitudinally running gauge reduction formations providing a narrow gauge reduction bridge between spaced thicker gauge portions, and a serpentine configuration profile extending in the longitudinal direction of the strip .

Preferred features of the strip correspond to the preferred strip features presented in accordance with the first aspect of the invention.

According to a further aspect, the invention provides a method of manufacturing a spacer airway fin matrix strip for a heat exchanger system, the method comprising forming an elongate strip of plastically deformable material to have one or more longitudinally running gauge reduction formations providing a narrow gauge reduction bridge between spaced thicker gauge portions, and a serpentine configuration profile extending in the longitudinal direction of the strip.

The invention will now be further described in specific embodiments and by way of example only with reference to the accompanying drawings, in which:

Figure 1 is a schematic perspective view of a heat exchanger system according to the invention;

Figure 2 is a schematic perspective view of a portion of the arrangement shown in Figure 1 ;

Figure 3 is a part sectional view of the fin airway matrix strip used in the arrangement of Figure 2;

Figures 4 to 7 are sectional views of alternative arrangements of airway matrix strip.

Referring to the drawings and initially Figure 1, there is shown a unified condenser radiator arrangement 1, comprising a vehicle radiator 2 assembled and brazed together with (and orientated forwardly of) an airconditioning circuit condenser 3. Radiator portion 2 is provided with respective spaced headers 4, 5 and a respective bank of tubes 6 spaced from one another and extending between the headers 4 , 5. Condenser 3 includes a corresponding pair of spaced headers 7, 8 and a respective bank of tubes 9 extending between the headers. Respective serpentine fin airway matrix strips 10 extend along the length of tubes 9, 10 in the respective banks and have a transverse dimension ensuring that the respective strips 10 span across the gap between the respective banks of tubes 6, 9. Typically the headers, tubes and fin strips 10 are of aluminium material (coated with a suitable brazing material) following assembly and jigging, the entire unified condenser radiator is braised in a single one shot process. The fin strips 10 are provided with louvre slit arrays 15, 16 for improved heat dissipation.

It is an important feature that the fin strips 10 span transversely to extend intermediate both banks of tubes 6, 9. If separate fin strips were used for each bank of tubes 6, 9, then airflow transversely through the unified condenser radiator arrangement will be disrupted resulting in less than optimum performance.

In view of the fact that the heat exchange fluids contained within respective banks of tubes 6, 9 will typically be at markedly different temperatures during vehicle operation, it is important to minimise heat transfer across the respective strips 10 between the two banks of tubes 6, 9. According to the present invention, this is achieved by forming in the strips 10 a median, longitudinally extending, gauge reduction zone 12 minimising the heat conduction cross- sectional area of the fin strip material 10 at a zone intermediate the respective of banks of tubes 6, 9.

As shown in Figures 2 and 3, the longitudinally running gauge reduction portion 12 may comprise, for example, a V- shaped notch or slot 13 provided in one surface of the strip.

As shown in Figures 4, 5 and 6, the notches may be of various shapes and, for example (as shown in Figure 4), provided on both sides of the strip 10 in order to provide a narrow waisted reduced portion 14.

In the embodiment shown in Figure 5, waisted portion 14 has been stretched transversely (plastically deformed in opposed directions of arrow A) to produce a very thin wasted portion 14.

In the arrangement shown in Figure 6, a pair of longitudinally running notches or grooves 13e,13d are provided in one surface of strip 10, complementarily arranged with a further groove or notch 13f in the other surface to provide a serpentine heat conduction path of reduced gauge between the opposed spaced fin portions of fin strip 10 .

Whilst the invention has been described primarily in a vehicle unified condenser radiator arrangement, it is clear that the invention is of benefit in heat exchanger systems where heat exchanger arrangements operating at different heat exchange fluid temperatures are combined as integral units. The provision of a reduced gauge portion rather than an aperture slitted or slotted portion intermediate the two banks of tubes provides for greater structural strength and integrity of the heat exchanger system, particularly in assembly prior to brazing although the structure strength and integrity of the final unit is also improved.

In thermal processes such as brazing, the gauge reduction portion may be tailored to be sufficiently thin to burn through providing a burn through aperture, slot or other formation. This provides a complete heat transfer barrier in the burn through zone .

Claims

Claims :

1. A heat exchanger system comprising:

2. A heat exchanger system according to claim 1, wherein the gauge reduction portion comprises a work hardened/plastically deformed portion.

3. A heat exchanger system according to claim 1 or claim 2, wherein the gauge reduction portion comprises a formation running along the strip in the longitudinal direction.

4. A heat exchanger system according to any preceding claim, wherein the gauge reduction formation comprises a notch, groove or channel formation formed at a first surface of the strip.

5. A heat exchanger system according to claim 4, wherein the gauge reduction portion comprises a notch, groove or channel formation formed at a first surface of the^{^} strip and a complementary configured notch, groove or channel formation formed at a second surface of the strip, a restricted waist portion being thereby defined.

6. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion includes material stretched (plastically deformed) in the direction of spacing of the banks of tubes.

7. A heat exchanger system according to any preceding claim, wherein the strip is formed in a serpentine configuration the gauge reduction portion extending longitudinally along a median line along the serpentine formed strip.

A heat exchanger system according to any preceding claim, wherein the gauge reduction portion extends longitudinally at a position intermediate the spaced banks of tubes .

9. A heat exchanger according to any preceding claim, wherein the gauge reduction portion provides a solid bridge between spaced portions of the strip interleaving the tubes in respective banks.

10. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion has a minimum material thickness reduced by 50% or more compared to the standard gauge of the strip portions interleaving the tubes in the banks.

11. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion has a minimum material thickness reduced by 60% or more compared to the standard gauge of the strip portions interleaving the tubes in the banks .

12. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion has a minimum material thickness reduced by 70% or more compared to the standard gauge of the strip portions interleaving the tubes in the banks .

13. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion has a minimum material thickness reduced by 80% or more compared to the standard gauge of the strip portions interleaving the tubes in the banks .

14. A heat exchanger system according to any preceding claim, wherein the gauge reduction portion comprises a plurality of gauge reduction formations running in the direction of the tubes and spaced from each other in side by side relationship.

15. A heat exchanger system according to any preceding claim substantially of brazed aluminium construction.

16. A heat exchanger system according to any preceding claim including:

17. A heat exchanger according to any preceding claim, herein 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 .

18. A heat exchanger system according to claim 17, 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.

19. An airway fin strip for a heat exchanger system, comprising a strip of material formed to have one or more gauge reduction formations providing a narrow gauge reduction bridge between spaced thicker gauge portions .

20. An airway fin matrix strip according to claim 19 comprising an elongate strip of material having one or more longitudinally running gauge reduction formations and a serpentine configuration profile extending in the longitudinal direction of the strip.

21. A method of manufacturing a spacer airway fin strip for a heat exchanger system, the method comprising forming an elongate strip of plastically deformable material to have one or more gauge reduction formations providing a narrow gauge reduction bridge between spaced thicker gauge portions.

22. A method according to claim 21, wherein the strip is elongate, the gauge reduction formations being orientated to run longitudinally, the strip having a serpentine configuration profile extending in the longitudinal direction of the strip.