Heat exchanger

Abstract

The heat exchanger is for cooling air by using water, particularly for use as an intercooler in an internal combustion engine. The heat exchanger has an elongate core assembly housed within a shell. The core assembly has a plurality of spaced apart tubes extending between an air inlet and an air outlet; a plurality of flow conduits disposed between and in thermal contact with the tubes, the flow conduits passing water across the core assembly generally at right angles to the air flow to transfer heat between the tubes and the water; and baffles disposed so that water enters the core assembly by a water inlet and propagates through the core assembly generally in the direction of the air flow axis along a tortuous path, along which the water absorbs heat from the tubes to cool the air, and exits through a water outlet.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Australian Patent Application Serial No. 2006905247, filed Sep. 21, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger for cooling air by water. In particular, the invention refers to a heat exchanger that can function as a charge air cooler in an internal combustion engine.

2. Description of the Related Art

Conventional heat exchangers, such as intercoolers, are used in large numbers of modern motor vehicles. An intercooler cools the hot air generated by the engine of a vehicle by passing the charge air through a plurality of parallel tubes, which are cooled by ambient air. To facilitate the cooling process, corrugated sheets are inserted between the air tubes such that the sheets are in thermal contact with the tubes. Ambient air is introduced on one side of the intercooler and is directed, along the surfaces of the corrugated sheets, to the other side of the intercooler. While moving through the cross section of the intercooler, the ambient air is in thermal contact with the tubes and the corrugated sheets. The ambient air absorbs heat from the tubes and the corrugated sheets, thus cooling the charge air passing through the tubes. Notably, the ambient air moves from one side of the intercooler to the other by simultaneously crossing the entire cross section of the intercooler's body.

While various improvements have been introduced to the size and configuration of the tubes and the arrangement between the tubes and corrugated sheets, the search continues for more efficient arrangements which provide better cooling and therefore better fuel efficiency. Thus, a heat exchanger solving the aforementioned problems is desired.

SUMMARY OF THE INVENTION

According to the invention, there is provided a heat exchanger for cooling a first fluid by a second fluid, the heat exchanger comprising an elongate core assembly extending along a first axis and housed within a shell, the core assembly having: a plurality of spaced apart tubes aligned with the first axis and extending between a first inlet, for introducing the first fluid into the tubes, and a first outlet, for exit of the first fluid from the tubes; a plurality of flow means disposed between and in thermal contact with the tubes, the flow means adapted to pass second fluid across the core assembly at right angles to the first axis and to transfer heat between the tubes and the second fluid; and baffle means engaged with the tubes, the arrangement being such that the second fluid enters the core assembly by a second inlet, propagates through the core assembly generally in the direction of the first axis, and exits the core assembly through a second outlet, wherein the baffle means cause the second fluid to move along the first axis in a tortuous path, along which the second fluid absorbs heat from the flow means and the tubes to cool the first fluid.

Preferably, the shell is of a cylindrical shape and the baffle means comprise a plurality of baffles alternatingly disposed along opposite sides of the core assembly, the baffles being of generally semicircular shape and configured to sealingly engage with the shell so as to define a plurality of adjacent longitudinal sections along the length of the core assembly arranged so that the second fluid is able to move between respective adjacent longitudinal sections only on the side of the core assembly opposite to a respective baffle; the arrangement being such that, in use, a pressurized second fluid is introduced in the exchanger via the second inlet at one side of the core assembly, the introduced second fluid being confined within a first of the longitudinal sections of the core assembly, by a respective baffle, and directed into the flow means in a first direction through the cross section of this longitudinal section, once reaching the opposite side of the core assembly, the second fluid being able to move to a second of the longitudinal sections, adjacent to the first longitudinal section, and second fluid being directed by the flow means through the cross section of the second longitudinal section in a direction opposite to the first direction, thus the second fluid consecutively traversing the cross sections of adjacent sections along the length of the core assembly in alternating directions, until reaching the second outlet and exiting the heat exchanger.

Even more preferably, the flow means comprises a corrugated sheet made of a heat conducting material. Preferably, each corrugated sheet is inserted between, and is abuttingly engaged with, at least a pair of adjacent tubes.

In some embodiments, the core assembly further includes a pair of baffles extending along the first axis on two mutually opposing sides of the core assembly to prevent the second fluid from moving around the periphery of the core assembly. Preferably, at least some of the tubes are flat tubes. Even more preferably, at least one tube has a cross section with at least one dimension that is different from the respective dimension of at least one other tube. Also preferably, the core assembly and the heat exchanger have substantially cylindrical shape.

In some embodiments, the tubes include internal fins extending inside the tubes to improve the heat exchange between the tubes and the first fluid. Preferably, the first fluid is air and the second fluid is water.

In some embodiments, the heat exchanger is arranged to function as an air-cooler in an internal combustion engine of a motor vehicle, and especially as an intercooler in turbocharged and/or supercharged engine.

These and other features of the present invention will become readily apparent upon further review of the following specification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of the heat exchanger according to a first embodiment of the invention.

FIG. 2 is an elevation view of the heat exchanger of FIG. 1.

FIG. 3 is a perspective view of the heat exchanger of FIGS. 1 and 2.

FIG. 4 is an end view of the heat exchanger of FIG. 3.

FIG. 5 is a plan view of the heat exchanger of FIG. 1, with the shell removed.

FIG. 6 is an elevation view of the heat exchanger of FIG. 2, with the shell removed.

FIG. 7 is a perspective view of the heat exchanger of FIG. 3, with the shell removed.

FIG. 8 is an end view of the heat exchanger opposite to the end view of FIG. 4.

FIG. 9 is a plan view of the core assembly of the heat exchanger of FIG. 1.

FIG. 10 is an elevation view of the core assembly of the heat exchanger of FIG. 2.

FIG. 11 is a perspective view of the core assembly of the heat exchanger of FIG. 3.

FIG. 12 is an end view of the core assembly of the heat exchanger of FIG. 4.

FIG. 13 is a perspective view of the core assembly of a heat exchanger according to a second embodiment of the invention.

FIG. 14 is an end view of the core assembly of FIG. 13.

FIG. 15 is an enlarged view of the portion shown in circle “E” of FIG. 14.

Similar reference characters denote corresponding features consistently throughout the attached drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The Figures depict one example of the heat exchanger according to the present invention. This is of a cylindrical intercooler, intended to be used as a charge air cooler in a turbocharged or supercharged internal combustion engine. This works to improve the efficiency of the engine, by increasing the density of the air charge by means of isochoric (i.e., constant volume) cooling. The reduction in the temperature of the air intake creates a denser charge of air into the engine, which causes better engine performance. In the present example, the heat exchanged uses water to cool the air charge.

FIGS. 1 to 4 depict a heat exchanger 1 for cooling air by water. It has a substantially cylindrical form around a longitudinal axis depicted as “X” in FIGS. 1 to 3. The heat exchanger 1 has a cylindrical shell 9 surrounding a core assembly 3, and an inlet 10 and an outlet 11 for the entry and exit, respectively, of water as the first fluid. Heat exchanger 1 also has inlet 20 and outlet 21 for the entry and exit respectively of air as the second fluid.

FIGS. 5 to 8 show heat exchanger 1 with shell 9 removed, thereby showing core assembly 3 in more detail.

FIGS. 9 to 12 show core assembly 3 by itself. Core assembly 3 comprises a plurality of spaced-apart flat tubes 4 disposed parallel to axis “X”. Tubes 4 are for passing air from inlet 20 to outlet 21. A plurality of corrugated sheets 5 are disposed between each pair of adjacent tubes 4 so as to be abutted against, and in thermal contact with, both tubes 4. Corrugated sheets 5 provide flow surfaces that allow the passage of water in a direction parallel to axis “Y”, shown in FIGS. 3 and 6. As can be clearly seen, axis “Y” is at right angles to axis “X”, as is axis “Z”.

While in this example the tubes 4 are generally at right angles to the corrugated sheets 5, it is possible in alternative embodiments of the invention to have these elements at angles other than at right angles. Preferably, these elements are at an angle between 60° and 120° to the perpendicular, so that they are within 30° from being a right angle. These elements may be at a variety of different angles, or all at the same angle. They may be arranged so that the average angle is about 90°, but with some elements are at a higher angle and an equal number at a lower angle than 90°. It is preferred that the elements are positioned to be close to, or at, right angles.

Once water enters the inlet 10, it is able to flow through corrugated sheets 5, following a tortuous path depicted by arrow “R” in FIG. 6. Ideally, the water is restricted to this tortuous path via a plurality of baffles 8, which is best shown in FIGS. 6 and 7.

Each baffle 8 extends in a plane perpendicular to axis “X”. As best shown in FIGS. 10 and 11, there are two end baffles 8a at opposed ends of core assembly 3. These end baffles 8a have a circular periphery, and the tubes 4 pass through them, as shown in FIGS. 11 and 12.

Other baffles 8b, 8c and 8d are disposed in various orientations between the pair of end baffles 8a. Some of the baffles 8b and 8c will each have a generally semi-circular form, each substantially half the size of end baffle 8a. In the example shown, there are two interior baffles 8b and one baffle 8c. Different numbers of these baffles may be employed. The baffles 8b are both offset by 180° from baffle 8c, which itself is disposed centrally along longitudinal axis “X” relative to and between the end baffles 8a. Baffles 8b are disposed longitudinally either side of baffle 8c.

Two further baffles 8d, are disposed opposite each other and parallel to axis “X”, so as to span between respective end tubes 4a and the shell 9. Water inlet 10 and outlet 11 are disposed near the respective air inlet 20 and outlet 21.

In the assembled configuration, the baffles sealingly engage the interior of cylindrical shell 9, defining a flow path schematically depicted by arrow “R” in FIG. 6. Water entering at inlet 10 initially at location “A” follows the tortuous path defined by the baffles 8, to pass through locations “B”, “C” and “D” prior to exiting at outlet 11.

In use, air enters inlet 20, passes through tubes 4 and exits at outlet 21, as shown by arrow “Q” in FIG. 6. Water enters inlet 10 near one end of heat exchanger 1, then follows the earlier described tortuous path depicted by arrow “R” and exits at outlet 11. The water is in effect flowing in a first direction from “A” to “B” parallel to axis “Y”, and then from “B” to “C”, it is flowing in an opposite direction. The water then once again changes direction between “C” and “D”, and finally once again between “D” and outlet 11.

As the water follows the tortuous path, it is constantly in thermal contact with tubes 4 and corrugated sheets 5. Consequently, along its path, the water continuously absorbs heat from tubes 4, thereby cooling the air passing through the heat exchanger 1, generally perpendicular to the path taken by the water.

Tubes 4 and corrugated sheets 5 may be made of conventional materials having good thermal conductivity. One such suitable material is aluminum. The tubes extend the first inlet and first outlet. Preferably, the tubes provide a direct route between, with a minimum path length, to allow the air to move through the exchanger with minimum disruption. The inlet and outlet may each have a chamber that connects with the tube interiors. Preferably, the exit and entrance to air flow may be of generally wide diameter, so as to minimally disrupt the air flow.

As can be seen in the example shown in FIG. 12, there are seven tubes 4, the central three of identical dimension, with the remaining four having progressively decreasing dimensions to fit within the circular envelope of the core assembly 3. Other numbers of tubes may be used.

FIGS. 13 to 15 depict a core assembly 3a, in a second embodiment. This core assembly 3a has its baffle configuration similar to that of the previously described core assembly 3 shown in FIG. 11. However, this core assembly 3a differs in that it comprises twenty spaced apart tubes 4b, in staggered relationship.

As can be seen as an expanded view in FIG. 15, tubes 4b can include internal fins 12. The fins extend inside the tubes and improve the heat exchange. It should be understood that such internal fins may also be used in the tubes 4 of the first embodiment.

It should be understood that in other embodiments the invention may involve other tube arrangements, as long as the tubes extend generally parallel to axis “X”, such that air can pass through them. The tubes may not need to be exactly parallel to axis “X”, but some or all may depart by some acute angle from this arrangement. However, the arrangement with the tubes in the parallel arrangement is preferred.

Experiments with the above-described system, used as an air-cooler in an internal combustion engine, indicate that the arrangement provides an efficient heat exchange between the hot air and the water. The improved cooling provides a better fuel efficiency. The shape and configuration of the heat exchanger also allows for an efficient heat exchange to occur in a compact design. Accordingly, the above-described system offers a useful alternative to the conventional heat exchangers for motor vehicles.

It should be appreciated that the disclosed heat exchanger is not limited to the particular embodiment described herein, but also covers other arrangements using similar concepts. For example, while the above-mentioned embodiments depict two tube arrays in FIGS. 12 and 14, many other not-shown tube arrays are possible without departing from the scope of the present invention.

It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.

Claims

1. A heat exchanger for cooling a first fluid by a second fluid, said heat exchanger comprising an elongate core assembly extending along a first axis and housed within a shell, said core assembly having:

a plurality of spaced apart tubes in a closed path aligned generally with said first axis and extending between a first inlet, for introducing said first fluid into the tubes, and a first outlet, for exit of said first fluid from the tubes;

a plurality of flow means disposed between and in thermal contact with said tubes, said flow means adapted to pass said second fluid across said core assembly about at right angles to said first axis and to allow heat transfer between the tubes and the second fluid; and

baffle means engaged with the exterior of said tubes,

the arrangement being such that said second fluid enters the core assembly by a second inlet, propagates through the core assembly generally in the direction of the first axis, and exits the core assembly through a second outlet, wherein the baffle means cause the second fluid to move along said first axis in a tortuous path, along which the second fluid is allowed to absorb heat from the flow means and the tubes so as to cool the first fluid.

2. A heat exchanger according to claim 1, wherein:

said shell is of a cylindrical shape and the baffle means comprise a plurality of baffles alternatingly disposed along opposite sides of the core assembly, the baffles being of generally semicircular shape and configured to sealingly engage with said shell so as to define a plurality of adjacent longitudinal sections along the length of the core assembly arranged so that the second fluid is able to move between respective adjacent longitudinal sections only on the side of the core assembly opposite to a respective baffle;

the arrangement being such that, in use, a pressurized second fluid is introduced in the exchanger via the second inlet at one side of the core assembly, the introduced second fluid being confined within a first of said longitudinal sections of the core assembly, by a respective baffle, and directed into the flow means in a first direction through the cross section of this longitudinal section, once reaching the opposite side of the core assembly, the second fluid being able to move to a second of said longitudinal sections, adjacent to the first longitudinal section, and second fluid being directed by the flow means through the cross section of the second longitudinal section in a direction opposite to the first direction, thus the second fluid consecutively traversing the cross sections of adjacent sections along the length of the core assembly in alternating directions, until reaching the second outlet and exiting the heat exchanger.

3. A heat exchanger according to claim 1, wherein each said plurality of flow means comprises a corrugated sheet made of a heat-conducting material.

4. A heat exchanger according to claim 3, wherein each corrugated sheet is inserted between, and is abuttingly engaged with, at least a pair of adjacent tubes.

5. A heat exchanger according to claim 2, wherein the core assembly further includes a pair of baffles extending along the first axis on two mutually opposing sides of the core assembly to prevent the second fluid from moving around the periphery of the core assembly.

6. A heat exchanger according to claim 1, wherein at least some of the tubes are flat tubes.

7. A heat exchanger according to claim 6, wherein at least one tube has a cross section with at least one dimension that is different from the respective dimension of at least one other tube.

8. A heat exchanger according to claim 1, wherein the core assembly and the heat exchanger have substantially cylindrical shape.

9. A heat exchanger according to claim 1, wherein the tubes include internal fins extending inside the tubes to improve the heat exchange between the tubes and the first fluid.

10. A heat exchanger according to claim 1, wherein the first fluid is air and the second fluid is water.

11. A heat exchanger according to claim 1, that functions as an air-cooler in a motor vehicle internal combustion engine.

12. The heat exchanger according to claim 11, that functions as an intercooler in a supercharged and/or turbocharged motor vehicle internal combustion engine.