EP3571073A1

EP3571073A1 - Heat exchanger, in particular evaporator, having a reservoir of phase change material

Info

Publication number: EP3571073A1
Application number: EP18705093.5A
Authority: EP
Inventors: Frédéric TISON; Sylvain Moreau; Lionel ROBILLON
Original assignee: Valeo Systemes Thermiques SAS
Current assignee: Valeo Systemes Thermiques SAS
Priority date: 2017-01-23
Filing date: 2018-01-23
Publication date: 2019-11-27
Also published as: CN110431028A; WO2018134442A1; FR3062199B1; FR3062199A1

Abstract

The invention proposes a heat exchanger, in particular an evaporator, comprising a heat exchange bundle delimiting a circuit for the circulation of heat-transfer fluid, the heat exchange bundle comprising at least one first tube in which the heat-transfer fluid flows, the heat exchanger further comprising at least one reservoir of phase change material in thermal contact with an outer face of the at least one first tube, the reservoir being delimited by a first reservoir plate and at least one opposing surface. According to the invention, the first reservoir plate has at least one support stud coming into contact with the opposing surface.

Description

Heat exchanger, in particular an evaporator, having a reservoir of material with phase change

1. Field of the invention

The field of the invention is that of heat exchangers, of the evaporator type in particular, for a motor vehicle.

More specifically, the invention relates to evaporators employing a phase change material.

2. Prior Art

In motor vehicles, it is known to implement an air conditioning device for regulating the temperature of the passenger compartment of the vehicle.

More specifically, these air conditioning devices implement an evaporator comprising a heat exchange beam formed of a stack of tubes and spacers for heat exchange between a flow of air passing through the beam (and more precisely through the spacers) and a coolant (such as a refrigerant) circulating in the tubes.

For vehicles equipped with an automatic engine shutdown system during short stops of the vehicle in particular, a function has been developed and allows, when the engine of the vehicle is stopped and no longer drives the compressor of setting circulation of the coolant, to maintain the cooling of the passenger compartment of the vehicle, thus improving the comfort of the passengers of the motor vehicle.

To do this, the heat exchanger implements a phase change material reservoir capable of storing cold when the engine of the motor vehicle is running and then return it to the air passing through the evaporator so as to cool it down. , for a limited time, when the vehicle engine is stopped. A heat exchanger of this type, partially illustrated in FIG. 1A, comprises a tank plate 20 which, after brazing with an external face of a tube 10 of the heat exchange bundle, forms a tank 21 of phase-change material. .

It is noted that, in a conventional manner, the tube 10 is obtained by brazing two plates 11A, 11B between which is disposed an inner spacer 12 (Figure 1B).

The tank 21 of phase change material is thus in thermal contact with an outer face of the tube 10, the tank being delimited by the tank plate 20 and an opposite surface corresponding to the outer face of the tube 10.

A disadvantage of this solution lies in the fact that, during brazing of the tank plate 20 on the tube 10, it can occur under the effect of the pressure due to the high temperature prevailing in the brazing furnace, a deformation of the tube 10 towards the interior of the tank 21.

Such deformation of the tube 10 is undesirable because it causes a reduction in the volume of the tank 21 of phase change material, and therefore the capacity of the tank 21 to store cold.

Furthermore, the deformation of the tube 10 during brazing can cause insufficient compression of the plates 11A, 11B against the inner spacer 12 of the tube 10.

This can lead to contact faults between the plates 11A, 11B and the inner spacer 12 during brazing, as illustrated in the detail view of FIG. 1B, and consequently cause, during use of the exchanger , the rupture of the tube 10 under the effect of the pressure of the coolant circulating in the tube 10.

There is therefore a need to provide a new type of heat exchanger having a reservoir of phase change material which, in at least one embodiment, overcomes the aforementioned drawbacks. 3. Summary of the invention

To this end, the invention proposes a heat exchanger, in particular an evaporator, comprising a heat exchange bundle delimiting a heat transfer fluid circulation circuit, the heat exchange bundle comprising at least a first tube in which said heat transfer fluid circulates, heat exchanger further comprising at least one phase change material reservoir in thermal contact with an outer face of said at least one first tube, the reservoir being defined by at least one first reservoir plate and an opposing surface.

According to the invention said first tank plate has at least one bearing pad coming into contact with said opposite surface.

The invention thus proposes a heat exchanger, and in particular an evaporator, comprising one or more tanks of phase change material.

Each reservoir comprises a first reservoir plate and an opposing surface, the latter being formed either by a second reservoir plate, or by an outer face of an adjacent tube.

In either case, the phase change material reservoir is in thermal contact with an adjacent or associated heat transfer fluid circulation tube.

The implementation on the first tank plate of one or more support pads coming to bear on the opposite surface of the reservoir ensures the compression of the adjacent tube and the elements constituting this tube (the two plates vis-à- screw and inner spacer) during the brazing cycle of the heat exchanger. This ensures a good resistance of the tube to the pressure stresses of the coolant circulating in the tube and reduces the risk of rupture of the contact between the elements constituting the tube.

This also prevents deformations of the adjacent tube during brazing of the exchanger, and prevents the tube is curved in the interior of the tank of material phase change.

According to a particular aspect of the invention, said at least one bearing pad protrudes inside the tank of phase change material.

According to another aspect of the invention, said tank of phase change material is delimited by the first tank plate contiguous to said at least one first tube of said heat exchange bundle, the opposite surface being formed by the external face of said less a first tube.

Thus, the phase-change material contained in the reservoir is in direct contact with the adjacent tube, which optimizes the heat exchange between the heat transfer fluid of the adjacent tube and the phase change material of the reservoir.

According to one aspect of the invention, said first tank plate has a plurality of support pads.

The choice of the number of support pads is a function of the stresses exerted during soldering on the heat exchange bundle.

According to another aspect of the invention, said support pads are distributed at several positions spaced along the length of said first tank plate.

According to one aspect of the invention, said support pads have a flat bottom.

According to another aspect of the invention, the flat bottom of said support pads is flush with the plane of the open surface of said first tank plate. Thus, the support pads come into contact with the outer face of the tube on which is brazed the tank plate.

According to one aspect of the invention, said first tank plate has bosses projecting in the opposite direction of the support pads, the bosses delimiting an air passage outside said tank of phase change material.

These bosses make it possible to slow down the flow of air that passes through the heat exchange bundle so as to optimize the heat exchange between the air and the exchanger.

According to another aspect of the invention, said bosses are intended to bear against a second adjacent tube.

According to one aspect of the invention, said tank of phase change material is delimited by said first tank plate and a second tank plate contiguous to the first tank plate, the opposite surface being formed by said second tank plate.

The reservoir of phase change material here consists of two tank plates, which increases the storage volume of the phase change material.

The second tank plate, which then forms the opposite surface, is in mechanical contact with the outer face of the adjacent tube.

According to another aspect of the invention, said second tank plate has support pads.

According to yet another aspect of the invention, said bearing pads respectively said first and second tank plates are located vis-à-vis and in contact.

This makes it possible to prevent the deformation of the tank plates during brazing of the exchanger and to ensure uniform compression of the tubes adjacent to the reservoir during brazing. The invention also proposes a tank plate intended to be implemented in a heat exchanger as described above and which has one or more support pads intended to come into contact with an outer face of a tube of the exchanger. or another tank plate, to form a reservoir of phase change material.

4. List of figures

Other characteristics and advantages of the heat exchangers according to the invention will appear more clearly on reading the following detailed description of particular embodiments of the invention, given as simple illustrative and nonlimiting examples, and the accompanying drawings. , among which:

FIG. 1A is a cross-sectional view of a part of a heat exchange bundle of a prior art heat exchanger using a reservoir of phase change material;

Figure 1B is a detail view of Figure 1A at a heat transfer fluid circulation tube;

Figure 1C is a partial view of the plate defining the reservoir of phase change material illustrated in Figure 1A;

FIG. 2A is an exploded partial view of a bundle of a heat exchanger according to the invention;

Figure 2B is a detail view of Figure 2A at a plate defining a reservoir of phase change material;

Figure 3A is a cross-sectional view of a portion of a beam of a heat exchanger according to the invention, illustrating a tube on which is brazed a phase change material tank plate;

Figure 3B is a detail view of Figure 3A;

Figure 3C is a partial view of the tank plate shown in Figure 3A; FIG. 4A is an exploded perspective view of part of the bundle of a heat exchanger according to the invention according to an alternative embodiment;

Figure 4B is a side view of the heat exchange bundle of Figure 4A.

5. Detailed description of the invention

In the different figures, unless otherwise indicated, the identical elements bear the same reference numbers and have the same technical characteristics and operating modes.

The embodiment described below is an evaporator designed for heat exchange between an air flow and a refrigerant, especially for an air conditioning device of the passenger compartment of a motor vehicle.

It goes without saying that the invention also covers a condenser, a radiator or any other heat exchanger, regardless of the fluid that passes through it.

The evaporator 1 according to the invention comprises a heat exchange bundle which is partially shown in FIG. 2A. In this figure, the illustrated portion of the beam of the evaporator 1 comprises:

two tubes 100 for the circulation of a coolant, each of the tubes being obtained by brazing two plates 101A, 101B between which is disposed an inner spacer 102;

a tank plate 200 disposed between the two tubes 100 and contiguous thereto, forming a storage tank for a phase change material; and

two external spacers 300 for the passage of a flow of air to be cooled through the heat exchange bundle of the evaporator 1. It is of course understood that the heat exchange bundle of the evaporator 1 may consist of of a plurality of stacked tubes 100 parallel with external spacers 300 in a longitudinal stacking direction.

The external spacers 300 are arranged between two neighboring heat transfer fluid circulation tubes and make it possible to increase the heat exchange surface with a flow of air which passes through the heat exchange bundle of the evaporator 1 passing between the tubes 100.

These external spacers 300 may have corrugations defining passages for the air flow in the direction of the width of the tubes.

Such external spacers 300 may be made of the same material as the tubes 100, for example of aluminum alloy.

One or more external spacers 300 are each substituted by a tank of phase change material which is capable of storing cold when the engine of the motor vehicle is running and then restoring it, for a limited time, to the air passing through the evaporator when the vehicle engine is stationary.

Such a tank of phase change material, formed of a tank plate 200 at least, will be described in more detail later in this description.

As illustrated in FIG. 3A, which is a cross-sectional view of a tube 100 on which a tank plate 200 is assembled, each tube 100 comprises two plates 101A, 101B stamped between which is placed an internal spacer 102 taking the form of corrugated iron.

More specifically, the plates 101A and 101B are stamped so as to form, after assembly, two adjacent conduits 110, 111.

The plates 101A, 101B and the spacer 102 are configured to be assembled together sealingly to form a plurality of channels 103 in each of the conduits 110, 111, inside which circulates a coolant, which is here a fluid refrigerant. Preferably, the plates 101A, 101B and the spacer 102 are brazed together to provide optimum sealing and mechanical strength.

A tank plate 200 is configured to be sealed, particularly by brazing, on an outer face of the tube 100 so as to form a reservoir 201 for storing a phase change material.

Although this is not illustrated, since it is a partial view of the evaporator 1, the tank plate 200 is contiguous with another tube 100 located above the tank plate 200.

In this embodiment, the reservoir 201 is formed of a first tank plate 200 and an opposite surface, which is constituted by an outer face of a tube 100.

Thus, the phase-change material stored in the reservoir 201 is in direct contact with the outer face of the tube 100, which facilitates and improves the heat exchange between the coolant circulating in the tube 100 and the stored phase change material. in the tank 201.

In the portion of the heat exchange bundle illustrated in FIG. 2A, each tube 100 comprises two external faces intended to be oriented towards a tank plate 200 and an outer spacer 300 respectively.

Each tube 100 further comprises two internal faces facing each other, and opposed to the external faces, between which is disposed the inner spacer 102.

The tank plate 200 has an open face whose periphery, or the periphery, 202 is intended to come into contact with the outer face of the upper tube 100, and to be brazed on the latter.

The underside of the tank plate 200, i.e. the face opposite to the open face, has a plurality of bosses 203 which are distributed over the entire tank plate 200. These bosses 203 protrude in a direction opposite to the open face of the tank plate 200 and perpendicular to the plane of the latter.

The bosses 203, which all have the same height, are distributed in the longitudinal plane of the tank plate 200 and define an air passage outside the tank 201 of phase change material.

In other words, when the evaporator 1 is assembled, the bosses 203 of the tank plate 200 coupled to a first tube 100 (the upper tube in FIG. 2A) are tangent or flush with the outer face of a second adjacent tube 100 (the lower tube in FIG. 2A) so that an air flow can flow between the tank plate 200 and the external face of the second tube 100 adjacent to the heat exchange bundle of the evaporator 1.

Thus, the air circulating between the tank plate 200 of the first tube 100 adjacent and the outer face of the second tube 100 adjacent is deflected and slowed by the bosses 203 to optimize the heat exchange between the evaporator 1 and the air which crosses it.

According to the invention, the tank plate 200 has at least one bearing pad 210 which is obtained by stamping the tank plate 200.

In the embodiment illustrated in FIG. 2A, the tank plate

200 has two bearing pads 210 which are substantially located in the center of the tank plate 200, along its longitudinal axis, and distributed in the width of the tank plate 200, vis-à-vis each of the conduits 110, 111 of the first tube 100 located above the tank plate 200.

A larger number of support pads 210 may be implemented on the tank plate 200 without departing from the general principle of the invention.

These bearing pads 210, which in this example have a planar bottom surface 211 (FIG. 2B), protrude in a direction opposite to the bosses 203. The bottom surface 211 of the bearing pads 210 extends flush with or in the same plane as the periphery 202 of the open surface of the tank plate 200, so that the bottom surface 211 of the pads support 210 comes into contact with the outer surface of the first tube 100 located above the tank plate 200 in Figure 2A and below in Figure 3A, after assembly of the tank plate 200 on the first tube 100.

Advantageously, this contact between the bottom surface 211 of the bearing pads 210 and the outer face of the first upper tube 100 ensures the compression of the latter between the outer spacer 300 and the tank plate 200, during the soldering of the bundle heat exchange.

Thus, as illustrated in FIG. 3B, which is a detail view of FIG. 3A, the implementation of these bearing pads 210 makes it possible to optimize the contact inside the first tube 100 between the plates 101A, 101B and the inner spacer 102 during brazing so as to ensure an optimal assembly of the first tube 100.

In other words, during brazing of the elements constituting the evaporator 1, the plates 101A, 101B and the inner spacer 102 which constitute the tube 100 are compressed between them on the one hand by an outer spacer 300 and on the other part by the support pads 210 of the tank plate 200, the bearing pads 210 applying a negative feedback, which allows a robust assembly of the plates 101A, 101B and the inner spacer 102, and therefore the tube 100.

The latter is thus able to withstand the pressure stresses generated by the circulation of the coolant in its inner channels 103, the pressure of the coolant conventionally having a nominal value of about 15 bar.

It should be noted, moreover, that the pressure due to the high temperature of the brazing furnace causing stresses on the walls of the tubes 100, the implementation of these bearing pads 210 prevents the deformations of the first tube 100 and prevents the latter from moving in the volume of the storage tank 201 of phase change material.

Other aspects and variants

In a variant of the invention (not shown), it is conceivable to implement only one and only support pad on a tank plate 200.

In this case, the single support pad must have dimensions enabling it to come into contact with the two ducts 110, 111 of the adjacent tube 100.

Furthermore, the number and the position of the support pads 210 on the tank plate 200 may vary according to the brazing temperature of the heat exchanger and the pressure stresses of the coolant circulating in the tubes 100.

The tank plates 200 and the plates 101A, 101B forming the tubes 100 are preferably made of an aluminum alloy sheet.

It is the same for the internal spacers 102, arranged in the tubes 100, and the external spacers 300 of the evaporator 1.

This aluminum alloy sheet may have a thickness of less than 0.3 mm, preferably between 0.24 and 0.28 mm.

More preferably, it implements a sheet of thickness less than or equal to 0.27 mm, for example equal to 0.25 mm.

In a variant of the invention, the tank 201 of phase change material consists of two identical tank plates 200 and contiguous to one another in "mirror", as shown in FIGS. 4A and 4B.

In other words, the tank 201 is formed of a first tank plate 200 and an opposite surface which is constituted by a second tank plate 200. The first and second tank plates 200 are assembled in a sealed manner, by brazing, for example.

These first and second tank plates 200 have bosses 203 defining an air passage outside the phase change material tank, between the tank plate 200 and an adjacent tube 100.

In addition, as illustrated in FIG. 4A, each of the first and second tank plates 200 has six bearing pads 210.

These bearing pads 210 are distributed over the length and the width of the tank plate 200.

In addition, the bearing pads 210 of the first tank plate 200 are located opposite the bearing pads 210 of the second tank plate 200.

Thus, during the assembly of the evaporator 1, the support pads 210 of each of the tank plates 200 come into contact with each other, which makes it possible to promote a good assembly of the adjacent tubes 100 which are compressed. on the one hand by the two tank plates 200 and on the other by an external spacer 300, as shown in Figure 4B.

The risk of rupture of contact between the elements (the plates 101A, 101B and the internal spacer 102) constituting the tubes 100, due to the pressure of the coolant circulating in the latter, are therefore avoided, unlike the prior art.

The total number of phase change material tanks and tank plates present within the heat exchange bundle of the evaporator 1 is a function of its size and length. The longer the heat exchange bundle, the greater the number, in order to ensure homogeneous cooling of the air during a compressor shutdown.

Multiple stacking variants of tubes 100, external spacers 300 or 201 tank of phase change material can be proposed without departing from the general principle of the invention.

Claims

Heat exchanger (1), in particular an evaporator, comprising a heat exchange bundle delimiting a heat transfer fluid circulation circuit, the heat exchange bundle comprising at least a first tube (100) in which said heat transfer fluid circulates, the heat exchanger thermal device (1) further comprising at least one tank (201) of phase change material in thermal contact with an outer face of said at least one first tube (100), the tank (201) being delimited by a first plate at least one tank (200) and an opposite surface,

characterized in that said first tank plate (200) has at least one bearing pad (210) contacting said opposite surface.

Heat exchanger (1) according to claim 1, characterized in that said at least one support pad (210) protrudes inside the reservoir (201) of phase change material.

Heat exchanger (1) according to claim 1 or 2, characterized in that said tank (201) of phase change material is delimited by the first tank plate (200) contiguous to said at least one first tube (100) of said beam heat exchange, the opposite surface being formed by the outer face of said at least a first tube (100).

Heat exchanger (1) according to one of claims 1 to 3, characterized in that said first tank plate (200) has a plurality of bearing pads (210).

Heat exchanger (1) according to claim 4, characterized in that said support pads (210) are distributed at several positions spaced along the length of said first tank plate (200).

6. Heat exchanger (1) according to one of claims 1 to 5, characterized in that said support pads (210) have a flat bottom (211).

7. Heat exchanger (1) according to claim 6, characterized in that the flat bottom (211) of said support pads (210) is flush with the plane of the open surface of said first tank plate (200).

8. Heat exchanger (1) according to one of claims 1 to 7, characterized in that said first tank plate (200) has bosses (203) projecting in the opposite direction of the support pads (210), the bosses (203) defining an air passage outside said reservoir (201) of phase change material.

9. heat exchanger (1) according to claim 8, characterized in that said bosses (203) are intended to abut on a second tube (100) adjacent.

10. Heat exchanger (1) according to claim 1 or 2, characterized in that said tank (201) of phase change material is delimited by said first tank plate (200) and a second tank plate (200) contiguous to said first tank plate (200), the opposite surface being formed by said second tank plate (200).

11. Heat exchanger (1) according to claim 10, characterized in that said second tank plate (200) has bearing pads (210).

12. Heat exchanger (1) according to claim 11, characterized in that said support pads (210) respectively said first and second tank plates (200) are located vis-à-vis and in contact.

13. tank plate (200) intended to be implemented in a heat exchanger (1) according to one of claims 1 to 12, characterized in that it has bearing pads (210) intended to come into contact with an external face of a tube of the exchanger or another tank plate, to form a reservoir of phase change material.