Heat-Exchanger Plate

Abstract

The present invention relates to a plate (1) for a flat-tube heat exchanger produced from a drawn metal sheet, said drawing enabling a fluid inlet (3a) and a fluid outlet (3b) to be connected together, said plate having a length (L) and a width (h), said fluid inlet and outlet (3a, 3b) being located along the length (L) of the plate, spaced apart from the edge of the plate by a distance corresponding to L/2, which is approximately 40 mm, wherein the drawing forms a first fluid flow passage (5a) located on a first side of said fluid inlet and outlet (3a, 3b) and a second fluid flow passage (5b) located on a second side of said fluid inlet and outlet (3a, 3b).

Description

The invention relates to the field of heat exchangers and more particularly flat tube heat exchangers used in the automotive field.

It is known practice in the automotive field to use heat exchangers comprising a stack of identical flat tubes through which a first fluid circulates. Each flat tube is formed of two sheets of metal sheet which are chased to form a dish with a predefined pattern and are arranged in such a way that their concave faces face one another. The two plates are then joined together in a fluidtight manner, thus forming a flat tube through which a fluid can circulate from a fluid inlet to a fluid outlet, the inlet and outlet each being situated at one end of the flat tube, and more generally each being situated on opposite sides of the plate.

The flat tubes are stacked on top of one another, the fluid inlets of each flat tube being joined together to form an inlet column. Likewise, the fluid outlets of each flat tube are joined together to form an outlet column. Between each flat tube is left a space for the passage of a second fluid. The exchange of heat between the two fluids therefore takes place as the first fluid passes through the flat tubes and the second fluid passes between said flat tubes.

It is also known practice, in order to increase the length of the flat tube and therefore the area for exchange of heat between the two fluids, to have the flat tube follow a winding circuit by keeping ribs on the plates at the time of chasing. In this type of exchanger, the inlet and outlet columns may thus be positioned on opposite sides of the plates or alternatively on the same side of the plates, as shown in application EP2105694.

Such heat exchangers are commonly used as evaporators in a refrigerant circuit for air conditioning the interior of a motor vehicle, this refrigerant constituting the first fluid and the second fluid being atmospheric air, or as a heating radiator in a heat transfer fluid circuit for heating the interior of a motor vehicle, this heat transfer fluid constituting the first fluid and the second fluid being atmospheric air.

However, when a long exchanger is being used to cool a flow of compressed air acting as second fluid, for example on the outlet side of a turbocompressor, and positioned as close as possible to the engine combustion cylinder air inlets, there is a problem because of the pressure head loss caused by the length of plate needed to best cover the surface area defined by all of the cylinders. Indeed, the effectiveness of the cooling of the second fluid, in this instance air, decreases with increasing distance away from the inlet column for the first fluid, for example water or a refrigerant.

One of the objects of the invention is therefore to at least partially overcome the disadvantages of the prior art and to propose a heat exchanger that limits the pressure head loss of the plates.

The present invention therefore relates to a plate for a flat tube of a heat exchanger, which plate is made from a chased metal sheet, said chasing allowing a fluid inlet and a fluid outlet to connect, said plate having a length L and a width l, said fluid inlet and outlet being situated along the length at a distance from the edge of the plate that corresponds to L/2, plus or minus 40 mm, and the chasing forming a first fluid flow passage situated on a first side of said fluid inlet and outlet, and a second fluid flow passage situated on a second side, the opposite side to the first, of said fluid inlet and outlet.

According to one aspect of the invention, the first and second fluid flow passages are symmetric with one another about an axis of symmetry that passes through the fluid inlet and outlet parallel to the width of said plate.

According to one aspect of the invention, the chasing comprises ribs that give the first and second passages a sinuous path comprising about-turns between the fluid inlet and the fluid outlet.

According to one aspect of the invention, the ribs have rounded ends.

According to another aspect of the invention, the first and second fluid flow passages comprise perturbation projections.

According to one aspect of the invention, the length of said plate is greater than or equal to 400 mm.

The invention also relates to a flat tube for a heat exchanger comprising at least one plate according to the preceding aspects.

According to another aspect of the invention, the flat tube for a heat exchanger comprises a first and a second plate according to the preceding aspects.

The invention also relates to a heat exchanger comprising at least one flat tube according to the preceding aspects.

According to another aspect of the invention, said heat exchanger is a charge air cooler.

Other features and advantages of the invention will become more clearly apparent from reading the following description, given by way of nonlimiting illustrative example, among which:

FIG. 1 is a schematic depiction of a plate for a flat tube of a heat exchanger,

FIG. 2 shows a schematic depiction of a heat exchanger with a fluid cooling circuit.

The plate 1 for a flat tube of a heat exchanger depicted in FIG. 1 has a length L and a width h. The plate 1, made from chased sheet metal, has a fluid inlet 3a and a fluid outlet 3b which are situated on the length L at a distance from the edge of the plate 1 that corresponds to L/2, plus or minus 40 mm. For preference, the fluid inlet 3a and fluid outlet 3b are situated in the center of the length L of the plate 1. The chasing of the plate 1 forms a cavity with ribs 7 defining a first and a second fluid flow passage 5a and 5b between the fluid inlet 3a and the fluid outlet 3b.

The ribs 7 give the first and second passages 5a, 5b a sinuous path comprising about-turns between the fluid inlet 3a and the fluid outlet 3b. This sinuous path makes it possible to increase the length of the first and second passages 5a, 5b and therefore increase the time for which the fluid is flowing in said first and second passages 5a, 5b, thereby increasing the time in which there can be transfer of heat from one fluid to another.

To facilitate this flow of fluid in the first and second passages, the ribs 7 may have rounded ends 11.

The first and second fluid flow passages 5a, 5b are symmetric with respect to one another about an axis of symmetry that passes through the fluid inlet and outlet 3a, 3b and is parallel to the width h of said plate 1. What this means to say is that they are identical to one another and have the same shape and the same length.

The flow passages 5a, 5b may also comprise perturbation projections 9 to make the fluid flowing along the flow passages 5a, 5b more homogeneous.

The flat tubes consist of the assembly of two plates 1 joined together, the flow passages 5a and 5b of each of the two plates facing one another. The plates 1 are assembled in a fluidtight fashion, to prevent any leaks of the fluid passing through the flow passages 5a, 5b.

Another way of embodying a flat tube may be to assemble a plate 1 with a flat plate resting on the periphery of the plate 1 and the ribs 7, covering the flow passages 5a, 5b.

A flat tube heat exchanger comprises a stack of flat tubes joined together at their fluid inlet and at their fluid outlet 3a, 3b, each flat tube being spaced apart so as to allow another fluid to pass between said flat tubes. The flat tubes are joined together at the fluid inlet and outlet 3a, 3b to form a fluid inlet column that groups together all the fluid inlets of all the flat tubes and a fluid outlet column that groups together all the fluid outlets of all the flat tubes.

Because of the use of plates 1 according to the invention for producing the flat tubes, the fluid inlet and outlet columns are situated at the center of the heat exchanger.

Thus, for the same length L of plate 1, and therefore of flat tube and of heat exchanger, the distance between the fluid inlets and outlets 3a and 3b and the end of the plate remains as short as possible, thereby limiting pressure head losses.

This feature is of all the more importance in heat exchanger flat tube plates 1 of a length L greater than or equal to 400 mm. This is because it is for such a length L that the pressure head losses are significant in plates of the prior art.

Thus, in the case of a heat exchanger positioned as close as possible to the engine combustion cylinder air inlets with a view to using a refrigerant circulating through the flat tubes to cool the flow of air arriving for example from a turbocompressor and rushing into each cylinder, the fact that the refrigerant inlet and outlet 3a, 3b are centered on the length L of the plates 1 means that said flow of air is cooled effectively even in the case of the combustion cylinders furthest away from the refrigerant inlet and outlets 3a, 3b, thus reducing the risks of auto-ignition.

In addition, such a configuration of the plates 1 notably makes it possible to obtain a heat exchanger 20 of the charge air cooler type, that is capable of cooling the same flow of air twice, as shown by FIG. 2.

Thus, to cool a flow of air arriving from the exhaust circuit 22, said flow of air is cooled a first time in the first flow passages 5a, before it is compressed and therefore heated up in a turbocompressor 24. The flow of air passes once again through the heat exchanger in the second flow passages 5b before rushing into the combustion cylinders 26.

This configuration means that it is possible to have just one refrigerant inlet column 30a and just one refrigerant outlet column 30b, thus making it possible to overcome the constraints and costs associated with the use of two heat exchangers which therefore require two refrigerant inlet columns and two refrigerant outlet columns.

Claims

1. A plate (1) for a flat tube of a heat exchanger, which plate (1) is made from a chased metal sheet which allows a fluid inlet (3a) and a fluid outlet (3b) to connect, the plate (1) having a length (L) and a width (h), wherein the fluid inlet and outlet (3a, 3b) are situated along the length (L) at a distance from the edge of the plate (1) that corresponds to L/2, plus or minus 40 mm, and wherein the chased metal sheet forms a first fluid flow passage (5a) situated on a first side of the fluid inlet and outlet (3a, 3b), and a second fluid flow passage (5b) situated on a second side, the opposite side to the first, of the fluid inlet and outlet (3a, 3b).

2. The plate (1) as claimed in claim 1, wherein the first and second fluid flow passages (5a, 5b) are symmetric with one another about an axis of symmetry that passes through the fluid inlet and outlet (3a, 3b) parallel to the width (h) of the plate (1).

3. The plate (1) as claimed in claim 1, wherein the chased metal sheet comprises ribs (7) that give the first and second fluid flow passages (5a, 5b) a sinuous path comprising about-turns between the fluid inlet (3a) and the fluid outlet (3b).

4. The plate (1) as claimed in claim 3, wherein the ribs (7) have rounded ends (11).

5. The plate (1) as claimed in claim 1, wherein the first and second fluid flow passages (5a, 5b) comprise perturbation projections (9).

6. The plate (1) as claimed in claim 1, wherein the length (L) of the plate (1) is greater than or equal to 400 mm.

7. A flat tube for a heat exchanger comprising at least one plate (1) as claimed in claim 1.

8. The flat tube for a heat exchanger as claimed in claim 7, comprising a first and a second plate (1).

9. A heat exchanger comprising at least one flat tube as claimed in claim 7.

10. The heat exchanger as claimed in claim 7, which is a charge air cooler.

11. The plate (1) as claimed in claim 2, wherein the chased metal sheet comprises ribs (7) that give the first and second fluid flow passages (5a, 5b) a sinuous path comprising about-turns between the fluid inlet (3a) and the fluid outlet (3b).

12. The plate (1) as claimed in claim 2, wherein the first and second fluid flow passages (5a, 5b) comprise perturbation projections (9).

13. The plate (1) as claimed in claim 3, wherein the first and second fluid flow passages (5a, 5b) comprise perturbation projections (9).

14. The plate (1) as claimed in claim 4, wherein the first and second fluid flow passages (5a, 5b) comprise perturbation projections (9).