WO2008107032A1

WO2008107032A1 - Heat exchanger for fluids circulating in a u shape

Info

Publication number: WO2008107032A1
Application number: PCT/EP2007/063741
Authority: WO
Inventors: Carlos Martins; Anne-Sylvie Magnier-Cathenod
Original assignee: Valeo Systemes Thermiques
Priority date: 2007-02-16
Filing date: 2007-12-11
Publication date: 2008-09-12
Also published as: FR2912811B1; EP2140218A1; FR2912811A1

Abstract

The present invention relates to an exchanger of heat between two fluids, comprising tubes (2, 2', 2') aligned parallel to one another and at least two header boxes (4), known as the inlet and outlet header boxes, for one of said fluids, termed the first fluid, said first fluid flowing through the tubes (2, 2', 2'), characterized in that it comprises at least one dividing wall (9) intended to form a U-shaped circuit for the second fluid; said wall comprising at least one aperture (22) to allow the second fluid to pass on each side of said wall (9) between at least two rows of tubes (T and 2').

Description

Title: Heat exchanger for U-flow fluids

The present invention relates to a heat exchanger for U-circulating fluids, in particular a high-pressure heat exchanger, that is to say having at least one circuit in which a high-pressure gas circulates, said circuit consisting of by tubes adapted for this high pressure gas.

Some of the heat exchangers that currently equip modern motor vehicles, including the air conditioning circuits of the passenger compartment of the motor vehicle, use a high-pressure coolant, for example CO2, which operates under a very high pressure which can reach several levels. hundreds of bars.

At present, patent FR 2852383 describes a particular arrangement for a header and a high pressure heat exchanger including this manifold.

The architecture described in this patent is particularly well suited for this type of heat exchanger, in particular from the point of view of its construction, its assembly, its small space requirement and its mechanical strength, but this device does not have good qualities or heat exchange performance. The present invention intends, from a structure or architecture substantially as described in the patent, to overcome the drawbacks of this type of exchanger by significantly improving their performance, while maintaining an equivalent space requirement.

Thus, the present invention relates to a heat exchanger between two fluids, comprising tubes aligned parallel to each other and at least two manifolds, called inlet and outlet manifold, for one of said fluids, said first fluid, said first fluid flowing in the tubes, characterized in that it comprises at least one partition wall for forming a U-shaped circuit for the second fluid; said wall comprising at least one recess to allow the passage of the second fluid on either side of said wall.

In other words, the heat exchanger according to the present invention is capable, compared to the heat exchanger of patent FR 2852383, in proposing a circuit for heat exchange between the two fluids having a double length.

Other particularities or characteristics are presented in the following:

the heat exchanger of the invention comprises at least one intermediate collector for the first fluid circulating in the tubes for its U-shaped circulation; Thus, the partition wall is optionally connected to this intermediate manifold, so that in this case, the first fluid passes through recesses in said partition wall. In the following, the invention will be described in the embodiment with the connection between the partition wall and the intermediate collector, the first fluid passing through recesses of said wall for its circulation in U. - The intermediate collector is formed by a stack or superposition, alternately, of first walls, called solid walls, and of second walls, called hollow walls, the hollow walls forming a space between the ends of tubes and the contiguous solid walls;

the aforesaid collector boxes are formed by an alternating superposition of first walls, called cap walls, and second walls, called spacer walls, the cap walls having through-cuts, the spacer walls having recesses, at least one part of the passage cuts of the cap walls overlapping the recesses of the spacer walls to form at least one channel for the first fluid; the separation wall comprises a first series of recesses for the U circulation of the second fluid;

the separation wall comprises a second series of recesses for the U-shaped circulation of the first fluid;

the aforesaid wall consists of a metal plate; the heat exchanger comprises two attached flanks, fixed laterally;

each side has an inlet / outlet manifold for one of the two fluids, said second fluid;

- The heat exchanger comprises two end plates, one of which has two inlet / outlet pipes for one of the two fluids, said first fluid;

the partition wall is connected and fixed to the manifolds and to the intermediate manifold;

- The heat exchanger also includes partition plates for making circulation passes for the first fluid.

The partition wall according to the invention makes it possible to obtain the U-shaped circulation simultaneously on the two fluids. Indeed, the return of each of the two fluids is provided solely by the partition wall because the ends of the heat exchanger are otherwise closed and do not allow the return of the fluid (s). Furthermore, the partition wall also has the function of increasing the mechanical strength of the exchanger, creating in particular a mechanical link between the two end walls.

It also has the function of increasing the mechanical strength of the exchanger, creating in particular a mechanical link between the 2 end walls.

An embodiment of the invention will be described below, by way of non-limiting example, with reference to the accompanying drawings in which: FIG. 1 represents a schematic view of a heat exchanger according to the invention,

FIG. 2 is an exploded view of the heat exchanger according to the invention,

FIG. 3 schematically represents a view from above of the heat exchanger according to the invention,

FIG. 4 is a sectional view of the exchanger according to the section AA illustrated in FIG. 3,

FIG. 5 is a sectional view of the exchanger according to section BB illustrated in FIG. 3; FIG. 6 is a sectional view of the exchanger according to section CC illustrated in FIG.

The present invention will be described for a use particularly adapted to a fluid / fluid exchanger in which at least one of the two fluids is a gas or quasi-gas (essentially consisting of gas), that is to say having a pressure greater than 50 bars. Of course, it can be provided to use this structure or architecture for a fluid / fluid exchanger where the two fluids are of the same nature, gas / quasi-gas or liquid / quasi-liquid.

Figure 1 is a perspective representation of a heat exchanger 1 according to the invention. It is constituted by the juxtaposition of a multiplicity of 2 planar tubes arranged parallel to each other. The tubes 2 are multichannel type. They are pierced internally with a multiplicity of parallel channels 3 intended, in the example, for the circulation of a fluid under high pressure, for example CO ₂ . A cap wall 4 is disposed at one end of each tube 2. A spacer wall 5 is interposed between each cap wall 4. There is thus an overlap, alternately, of a cap wall 4 and a spacer wall 5.

In the example shown, the cap walls 4 and the spacer walls 5 are constituted by individualized elements, separated from each other, cut individually in a sheet. The cap walls 4 and the spacer walls 5 thus constitute individual plate-shaped elements constituting cap plates 4 and spacer plates 5. In the example, the spacer plates 5 comprise two circular cutouts 7, 8.

Similarly, the walls or cover plates 4 comprise two cutouts 7 ', 8'. However, while the through-cuts 7, 8 of the spacer plates 5 are closed, the cut-outs 1 1 of the cover plates 4 are open so as to have a housing cut-out adapted to receive the end of the tube 2 to 1. end of which they are mounted. The cut-outs 7 ', 8' are thus in fluid communication with the multiple longitudinal channels 3 of the multi-channel tubes 2. The cut-outs 7 'are in communication with the tubes 2', while the others cutouts 8 'of passage are in fluid communication with the other tubes

2 ".

The passage cutouts 7, 8 of the spacer plates 5 and the cut-outs 7 ', 8' of the cover plates 4 are superposed, at least in part, in order to produce fluid channels for the distribution of the coolant in the tubes. 2.

It is also possible to provide partition plates, not shown in the accompanying figures but in accordance with those of patent FR 2852383, which have no cut. The replacement of a spacer plate by a partition plate closes the fluid channels, which makes it possible conventionally to make passes for the circulation of the first fluid which circulates in the tubes.

Thus, the first object of the invention is to provide a U-shaped circulation for at least one of the fluids thanks to the partition wall 9, the U-shaped circuit extending horizontally, that is to say in the plane of Extension of the tubes 2 or inter-tube conduits 18. Moreover, thanks to the partition plates, it will be possible to create passes for the circulation of the first fluid so that its circulation is also vertical or perpendicular to the U-shaped circulation plane made possible by to the circulation wall 9.

Finally, the heat exchanger comprises an upper end plate 10 and a lower end plate 11. The end plate 10 has two cut-outs which are superimposed on the cut-outs of the spacer plate 5 attached to the end plate. end 10. The cuts allow the connection of the inlet pipes 12 and outlet 13 for the fluid, for example CO 2.

The exchanger according to the invention comprises alternately at one end a cap plate 4 and a spacer plate 5 and at the other end a solid plate 14 and a hollow plate 15. The space defined between two tubes 2 is equal to the thickness of the spacer plates 5. This space is therefore not important. Consequently, an exchanger of this type is particularly suitable for liquid / gas exchange.

The heat exchanger according to the present invention differs from that described in patent FR 2852383 essentially in that the walls spacer 5 / cap 4 and the solid walls 14 / hollow 15 are adapted to accommodate a partition wall 9.

Thus, in the example chosen to illustrate the invention, on the side of the exchanger 1 housing a manifold 4, 5 for the refrigerant or supercritical fluid, the spacer walls 5 and the cap walls 4 have a slot or a recess 16 intended to receive one end of the partition wall 9.

On the opposite side to the manifold 4, 5 for the refrigerant or supercritical fluid, the heat exchanger 1 also comprises two types of stacked walls, called the solid walls 14 and the hollow walls 15. The hollow walls 15 are fixed in screws with respect to the ends of the tubes 2, and therefore also of the cap walls 4, so that the circulation of the fluid conveyed by the tubes 2 can be made from a contiguous tube 2 'to the other 2 "while the walls 14 are facing the walls 5 and extend beyond the ends of the tubes 2 so that the fluid flowing in the tubes 2 can not pass or circulate between the tubes 2 located at different heights or levels.

In the example chosen to illustrate the invention, the heat exchanger 1 is closed by a housing or the like consisting of two end plates 10, 11, located respectively below 11 and above 10 of the stack of 2 and / or walls 4, 5, 14, 15, and two side plates 16, 17 laterally closing the exchanger 1 and forming the side walls of the ducts or inter-tube passages 18. Of course, we can provide that the tubes 2 themselves form or include the means for closing the inter-tube ducts 18.

The side plates 16, 17 each comprise a tubing respectively inlet 19 and outlet 20 of fluid, in this case heat transfer fluid (mixture of water + glycol) while the end plate 10 comprises two pipes 1, respectively input 13 and output 12, for the circulation of the refrigerant, for example of CO2 type.

All the elements of the heat exchanger 1 according to the invention is brazed together so as to result in a compact and resistant structure.

The partition wall 9 comprises two types of recesses 21, 22, which function of the two fluid circuits of the heat exchanger 1 according to the invention. Indeed, the heat exchanger 1 of the invention comprises two fluid circulation circuits, in this case relative to the object of the invention set out here, one of the fluids is essentially in gaseous form and the other fluid is essentially in liquid form. The fluid essentially in gaseous form consists of a refrigerant or supercritical fluid of CO2 type (also called R744) or for example fluid H; this fluid being used for the air conditioning of the motor vehicle. The fluid essentially in liquid form consists of a coolant such as for example a mixture of water and glycol and is conventionally used to cool the engine of the motor vehicle.

The circuit for the fluid essentially in gaseous form starts from the tubes 12, 13 located on the end plate 11. This fluid then passes into the inlet manifold 4, 5 formed by the cap walls 4 and the recesses of the spacer walls. 5. The first row 2 'of tubes 2 opening into this inlet manifold, this fluid flows in the tubes T of this first row up into the plurality of intermediate collectors, each formed by the hollow walls 15. The fluid substantially gaseous then passes through the recesses or orifices 21, here consisting of circular recesses present in the partition wall 9 to reach the second row 2 "of tubes 2. The gaseous fluid then passes through the tubes 2" of this second row to lead to the formed outlet manifold, like the manifold inlet, by stacking the walls cap 4 and walls spacer 5. This fluid arr Into the outlet manifold is then evacuated through the outlet manifold 12, or second manifold, present on the endplate 11.

The circuit for the essentially liquid fluid starts from one of the tubes 19 provided on one of the side walls 16. This fluid circulates in the ducts 18 formed by the space between two contiguous tubes 2, called the inter-tube duct. Thus, the fluid coming from the inlet pipe 19 is distributed in the plurality of inter-tube conduits 18 of the exchanger 1, here for example between the tubes of the second row 2 ", to go to the holes or recesses 22 of the partition wall 9 to circulate in the inter-tube ducts 18 formed by the tubes 2 'contiguous or adjacent to the first row of tubes, and finally out through the outlet pipe 20. For the second fluid, the second fluid circuit also performs a U in order to exchange heat better with the first fluid. Thus, in the structure of the heat exchanger according to the invention, it is particularly important that the inlet 19 of the second fluid is located at a distance from the holes or recesses 22 so that this fluid flows over the entire length, or almost the entire length of the inter-tube duct 18.

Furthermore, it is desirable for the flow of the two fluids to be against or counter-current and to provide for the second fluid (or first fluid) to begin to exchange with the first fluid (or second fluid) at its outlet section. 2 "corresponding to the inlet section for the second fluid so as to optimize the heat exchange performance between the fluids.

The holes or recesses 21 for the first fluid, namely the essentially gaseous fluid, are here circular while the holes or recesses 22 for the second fluid, namely the essentially liquid fluid, has a larger section, here therefore elongated .

Those skilled in the art can apply this concept to many other similar systems without departing from the scope of the invention defined in the appended claims.

Claims

1. heat exchanger (1) between two fluids, comprising tubes (2, 2 ', 2 ") aligned parallel to each other and at least two collector boxes (4, 5), called collector box; inlet and outlet, for one of said fluids, said first fluid, said first fluid flowing in the tubes (2, 2 ', 2 "), characterized in that it comprises at least one partition wall (9) intended forming a U-shaped circuit for the second fluid; said wall comprising at least one recess (22) to allow the passage of the second fluid on either side of said wall (9) between at least two rows of tubes (T and 2 ").

2. Heat exchanger (1) according to claim 1, characterized in that it comprises at least one intermediate collector (15) for the first fluid flowing in the tubes (2, 2 ', 2 ") for its circulation in U .

3. Heat exchanger (1) according to claim 2, characterized in that the intermediate manifold (15) is formed by a stack or superposition, alternately, first walls, called solid walls (14), and second walls, called hollow walls (15), the hollow walls (15) forming a space between the tube ends (2, 2 ', 2 ") and the contiguous solid walls (14).

4. Heat exchanger (1) according to any one of the preceding claims, characterized in that the aforesaid collector boxes (4, 5) are formed by an alternating superposition of first walls, called cap walls (4), and second walls, called spacer walls (5), the cover walls (4) having cut-outs, the spacer walls (5) having recesses, at least a portion of the cut-outs of the cover walls (4) overlapping to the recesses of the spacer walls (5) to form at least one channel for the first fluid.

5. heat exchanger (1) according to any one of the preceding claims, characterized in that the partition wall (9) comprises a first series of recesses (22) for the U-shaped circulation of the second fluid.

6. Heat exchanger (1) according to any one of the preceding claims, characterized in that the partition wall (9) comprises a second series of recesses (21) for the U-shaped circulation of the first fluid.

7. heat exchanger (1) according to any one of the preceding claims, characterized in that the aforesaid wall (9) consists of a metal plate.

8. heat exchanger (1) according to any one of the preceding claims, characterized in that it comprises two sidewalls reported (16 and 17), fixed laterally.

9. heat exchanger (1) according to the preceding claim, characterized in that each flank (16, 17) comprises an inlet / outlet manifold (19, 20) for one of the two fluids, said second fluid.

10. Heat exchanger (1) according to any one of the preceding claims, characterized in that it comprises two end plates (10, 1 1), one (10) has two inlet / outlet pipes (12, 13) for one of the two fluids, said first fluid.

11. heat exchanger (1) according to claims 1 and 2, characterized in that the partition wall (9) is connected and fixed to the manifolds (4, 5) and the intermediate manifold (15).

Heat exchanger (1) according to one of the claims preceding, characterized in that it also comprises partition plates for making circulation passes for the first fluid.