WO1999001712A1

WO1999001712A1 - A heat exchanger card and a heat exchanger incorporating same

Info

Publication number: WO1999001712A1
Application number: PCT/AU1998/000515
Authority: WO
Inventors: Kim Francis Ledger
Original assignee: Act 6 Pty. Ltd.; HECT Limited
Priority date: 1997-07-03
Filing date: 1998-07-03
Publication date: 1999-01-14

Abstract

A heat exchanger card (10) is made of a heat conductive material and is provided with an integral meandering conduit (12). The conduit (12) has an inlet (14) and an outlet (16) which each open at edge (18) of the card (10). Slots (20 and 22) are cut in the card (10) to form gaps (24 and 26) respectively which divide the card (10) into national sections (28, 30 and 32). The slots (20 and 22) extend between lengths of the conduit (12) which pass each other.

Description

Title

A HEAT EXCHANGER CARD AND A

HEAT EXCHANGER INCORPORATING SAME

Field of the Invention

The present invention relates to a heat exchanger card and to a heat exchanger comprising a bank of such heat exchanger cards.

Background of the Invention

Several physical processes are involved with the transfer of heat, these being primarily conduction, convection and radiation. Convection for the purposes of cooling or heating relies on laminar or turbulent flow where fluid particles flow or mix side by side and in doing so transfer heat.

An example where convection is the primary process in heat transfer is in a radiator for an internal combustion engine. Such radiators comprise a top tank which receives water from the engine, a core through which water from the top tank can flow, and a bottom tank which receives water from the core. The bottom tank is provided with an outlet for supplying cooled liquid back to the engine. The core comprises a plurality of elongate core tubes which provide fluid communication between the top tank and bottom tank. A motor driven water pump creates a vacuum or suction at the bottom tank to generate fluid flow through the motor and subsequently the core tubes. The core tubes dissipate heat via many fine fins attached along the core tubes at regular intervals. Current radiators rely on a large area of the core (ie. core tubes and in particular the fins) to be exposed to direct air flow for maximum cooling efficiencies.

While this type of conventional radiator is, by current standards, relatively efficient, it does have several draw backs. Notably, the radiator is relatively large and generally must be placed at the front of the vehicle in order to be disposed in an air flow created when the vehicle moves. Consequently, the frontal design of most vehicles is limited by the physical constraints on the radiator. This in turn limits the aerodynamic efficiency of the vehicle design. Also, the fins attached to the core tubes which are used to dissipate heat are only in line or edge contact with the tube. Accordingly, the total surface area of the tube which is contacted by a fin is at best in the order of 30%. As the remainder of the core tube is not in contact with the fin, heat transfer is limited.

Summary of the Invention

It is an object of the present invention, to provide a heat exchanger card and a heat exchanger incorporating a bank of such cards which can be constructed in a more compact manner and provide comparable if not better heat transfer characteristics.

According to a first aspect of the present invention there is provided a heat exchanger card made of a heat conductive material and provided with: an integral meandering conduit having an inlet and an outlet each opening at an edge of the card; and, at least one slot cut in the card and extending between lengths of the conduit that pass each other to form gaps that divide the card into a number of sections and thereby limit heat transfer between different sections of the card; whereby, in use, when a first fluid is passed through the conduit from the inlet to the outlet, heat can be exchanged from the first fluid to a second fluid enveloping the heat exchanger card via the sections of the card.

Preferably the inlet and the outlet open onto the same edge of the card.

Preferably the edge of the card containing the inlet and the edge of the card containing the outlet are profiled to assist in creating turbulent flow of the second fluid across the card.

Preferably when the inlet and the outlet both open onto a first edge of the card, opposite edges of the card transverse to the first edge are profiled to assist in creating turbulent flow of the second fluid across the card.

Preferably the card further includes a separate coupling member attached to each of the inlet and the outlet to enable fluid-tight demountable coupling of the inlet and the outlet to respective fluid transfer tanks.

According to another aspect of the present invention there is provided a heat exchanger including: a primary fluid transfer tank; a secondary fluid transfer tank; and, a bank of heat exchanger cards according to the first aspect of this invention; wherein the inlet of each card is connected to the primary tank and the outlet of each card is connected to the secondary tank, whereby, a first fluid in the primary tank can flow to the secondary tank through the bank of heat exchanger cards so that the heat can be exchanged between the first fluid flowing through the bank of cards and a second fluid enveloping the cards.

Advantageously, the heat exchanger includes coupling means enabling a fluid-tight demountable coupling between the cards and the primary and secondary tanks.

Preferably the coupling means comprises a click-type fluid connector to enable mounting and demounting of the cards from the primary and secondary tanks without the use of hand tools.

According to another aspect of the present invention there is provided a heat exchanger including: a primary fluid transfer tank; a secondary fluid transfer tank; a bank of heat exchanger cards, each exchanger card being made of a heat conductive material and provided with an integral meandering conduit having an inlet and an outlet each opening at an edge of the card; and, a separate coupling member attached to each of the inlet and the outlet to enable fluid tight demountable coupling of the inlet and the outlet to the primary and secondary fluid transfer tanks respectively.

Brief Description of the Drawings

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

Figure 1 is a plan view of a first embodiment of the heat exchanger card;

Figure 2 is a plan view of a second embodiment of the heat exchanger card;

Figure 3 illustrates one method of manufacture of the card shown in Figures 1 and 2;

Figure 4 is a plan view of a part of a heat exchanger which can incorporate the heat exchanger card shown in Figures 1-3;

Figure 5 is a plan view of a completed heat exchanger;

Figure 6 is a plan view of a second embodiment of a heat exchanger; and,

Figure 7 is a front view of a heat exchanger card for use in the heat exchanger shown in Figure 6.

Detailed Description of the Preferred Embodiments

Referring to Figures 1-3, it can be seen that a heat exchanger card 10, which is made of a heat conductive material such as copper or another metal, is provided with an integral meandering conduit 12. The conduit 12 has an inlet 14 and an outlet 16 which each open at edge 18 of the card 10. Slots 20 and 22 are cut in the card 10 to form gaps 24 and 26 respectively which divide the card 10 into a number of notional sections 28, 30 and 32. It will be further seen that the slots 20 and 22 extend between lengths of the conduit 12 that pass each other. For example, conduit 12 can be notionally divided into separate lengths 12A-12G. The slot 20 extends between length 12 A; and, lengths 12C-12G. Also, slot 22 extends between lengths 12D and 12F that pass each other.

The gaps 24 and 26 limit heat transfer between different sections 28, 30 and 32 of the card 10. This increases the efficiency of the card 10 when used to cool a liquid passing through the conduit 12.

In use, a first fluid is passed through the conduit 12 from inlet 14 to outlet 16. A second fluid (refer Figure 2) such as air, envelopes and passes over the external surface 34 of the card 10 as shown by arrows A. Heat is transferred from the first fluid flowing through the conduit 12 to the air via the body of the card 10 which in effect acts as a fin similar to that in prior art radiators discussed above.

To enhance the heat transfer characteristics, opposing edges 36 and 38 of the card 10 can be shaped or otherwise configured so as to promote flow, turbulence and pressure variations in the air.

Couplings 40 and 42 are provided at the inlet 14 and outlet 16 respectively. The couplings 40 and 42 are of the type which provide fluid tight demountable coupling to a conduit or tank. In particular, as discussed in greater detail below, the couplings 40 and 42 provide a demountable fluid tight connection between the cards 10 and inlet and receive tanks of a heat exchanger.

Figure 3 illustrates one method of manufacture of the cards 10. In this method, each card 10 is made of separate plates 44 and 46 each of which is formed with respective channels 48 and 50 which are at corresponding locations so that when the plates 44 and 46 are joined in the face to face relationship, the channels 48 and 50 form the conduit 12. The plates 44 and 46 can also be provided with slots 20A and 20B which together form the slot 20 in the fabricated card 10. Each plate 44 and 46 can be made by casting, press fabrication, or investment moulding. Further, the plates 44, 46 can be made from various conductive materials such as aluminium, copper, stainless steel or brass, and joined by any suitable means sufficient to effect correct sealing of the conduit 12.

The couplings 40 and 42 may be formed integrally with the plates 44 and 46. However, in an alternate embodiment, the couplings can be made separately and then fixed to the inlet and outlet.

In use, the cards 10 form part of a heat exchanger 52 depicted in Figures 4 and 5. The heat exchanger 52 is provided with two transfer tanks 54 and 56 which are in the form of metal or plastic tubes sealed at one end and provided with a row of holes 54H and 56H respectively along their length. The tanks 54 and 56 are disposed parallel to each other but are open at diametrically opposite ends 54E and 56E respectively. Struts 58 and 60 extend transversely between and are connected to the tanks 54 and 56 to provide structural rigidity. The heat exchanger 52 is completed by coupling a bank of cards 10 to the tanks 54 and 56. Specifically, the couplings 40 at the inlet 14 are coupled to the holes 56H and the couplings 42 at outlet 16 are coupled to the corresponding opposite holes 54H of the tank 54.

The heat exchanger 52 can typically be used as a radiator in a vehicle. As such, coolant from the vehicle can be delivered to the opening 56E and a water pump connected to the opening 54E. The water pump will draw water from the engine through the tank 56H so as to pass into the inlet 14 of each card 10 then through the conduit 12 of each card to the outlet 16 to be received in the tank 54 to pass back to the engine. As the coolant flows through the conduits 12, it is cooled through convection and conduction via air enveloping and passing through and around the cards 10.

It will be appreciated that the heat exchanger 52 has a substantially smaller height dimension than a convention vehicle radiator. This is because the length of core tubes of a conventional radiator is substantially reduced by forming the conduit 12 in a meandering manner so as to pass itself one or more times on the card 10. Further, the body of the card 10 provides a larger fin surface area for the conduit 12 than do the fins of a conventional radiator thereby allowing a further reduction in dimension. The heat exchanger 52 is also less likely to become blocked as there are relatively large spaces between adjacent cards 10. In the event of a card 10 being damaged, it can be simply clicked out of the heat exchanger 52 and replaced with a fresh card. Indeed the heat exchanger 52 can be made of variable capacity by taking out a number of the cards 10 and placing stops or bungs in the vacant holes 54H and 56H. Because of the compact size of the heat exchanger 52, it can be placed anywhere around the body of the vehicle to enhance the styling options for vehicles and their aerodynamics. For example, exchangers 52 can be placed along the side of the engine bay adjacent air intakes formed along the side of the vehicle.

Figures 6 and 7 show an alternate embodiment of the heat exchanger 52'. The features of the heat exchanger 52' which correspond to those of the heat exchanger 52 are depicted by the same reference numerals but with the addition of a prime (') mark. The main difference between the heat exchanger 52' and heat exchanger 52 resides in the use of the heat exchanger cards 10'. The cards 10' (shown in Figure 7) do not include slots 20 or 22. Also, the conduit 12' is of a simpler shape, being essentially in the shape of an inverted U and of larger width than the conduit 12.

In the heat exchanger card 10 when used for cooling, it is important that the inlet 14 and outlet 16 be thermally isolated from each other so that the outlet is not heated by the fluid entering the inlet. However, when the heat exchanger 52' is used for heating, this is of no concern therefore the slots 20 and 22 are not required. Essentially in all other aspects the heat exchanger 52 is the same as heat exchanger 52'. A gas burner 62 is located adjacent the exchanger 52' to provide hot air to envelope the cards 10' and act as a source of heat for fluid passing through the cards 10'.

Now that embodiments of the present invention have been described in detail, it will be apparent to those skilled in the relevant arts, that numerous modifications and variations may be made without departing from the basic inventive concepts. For example, the precise configuration of the conduit 12 can vary significantly from that shown in Figures 1 and 7. Also, it is not essential that the inlet 14 and outlet 16 open onto the same edge of the card 10. Also, the card 10 can be provided with any number of slots not just the two slots shown. Additionally, the slots need not be of linear configuration and can of course take other shapes. Finally, the heat exchangers 52 and 52' can be applied to any conventional heat exchange environment such as radiators, oil coolers, inter-coolers, liquid to liquid coolers, and air conditioning condensers.

All such modifications and variations are deemed to be within the scope of the present invention, the nature of which is to be determined from the foregoing description and the appended claims.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A heat exchanger card made of a heat conductive material and provided with: an integral meandering conduit having an inlet and an outlet each opening at an edge of the card; and, at least one slot cut in the card and extending between lengths of the conduit that pass each other to form gaps that divide the card into a number of sections and thereby limit heat transfer between different sections of the card; whereby, in use, when a first fluid is passed through the conduit from the inlet to the outlet, heat can be exchanged from the first fluid to a second fluid enveloping the heat exchanger card via the sections of the card.

2. A heat exchanger card according to claim 1 wherein, the inlet and the outlet open onto the same edge of the card.

3. A heat exchanger card according to claim 1 wherein, the edge of the card containing the inlet and the edge of the card containing the outlet are profiled to assist in creating turbulent flow of the second fluid across the card.

4. A heat exchanger card according to claim 1 wherein, the inlet and the outlet both open onto a first edge of the card and opposite edges of the card transverse to the first edge are profiled to assist in creating turbulent flow of the second fluid across the card.

5. A heat exchanger card according to claim 1 further including a separate coupling member attached to each of the inlet and the outlet to enable fluid- tight demountable coupling of the inlet and the outlet to respective fluid transfer tanks.

6. A heat exchanger including: a primary fluid transfer tank; a secondary fluid transfer tank; and, a bank of heat exchanger cards, each of said heat exchanger cards in accordance with claim 1, wherein the inlet of each card is connected to the primary tank and the outlet of each card is connected to the secondary tank, whereby, a first fluid in the primary tank can flow to the secondary tank through the bank of heat exchanger cards so that the heat can be exchanged between the first fluid flowing through the bank of cards and a second fluid enveloping the cards.

7. A heat exchanger according to claim 6 further including coupling means enabling a fluid-tight demountable coupling between the cards and the primary and secondary tanks.

8. A heat exchanger according to claim 7 wherein, the coupling means comprises a click-type fluid connector to enable mounting and demounting of the cards from the primary and secondary tanks without the use of hand tools.

9. A heat exchanger including: a primary fluid transfer tank; a secondary fluid transfer tank; a bank of heat exchanger cards, each exchanger card being made of a heat conductive material and provided with an integral meandering conduit having an inlet and an outlet each opening at an edge of the card; and, a separate coupling member attached to each of the inlet and the outlet to enable fluid tight demountable coupling of the inlet and the outlet to the primary and secondary fluid transfer tanks respectively.