WO2018020139A1

WO2018020139A1 - Heat exchanger, particularly for the thermal regulation of an energy-reserve unit, and assembly formed of said exchanger and of said unit

Info

Publication number: WO2018020139A1
Application number: PCT/FR2017/052065
Authority: WO
Inventors: Christophe Denoual; Lionel ROBILLON
Original assignee: Valeo Systemes Thermiques
Priority date: 2016-07-26
Filing date: 2017-07-25
Publication date: 2018-02-01
Also published as: FR3054650B1; FR3054650A1

Abstract

The present invention relates to a heat exchanger (1), notably for thermal regulation of an energy-reserve unit (100), said exchanger (1) comprising a heat exchange bundle (2) equipped with tubes (4) for circulation of a fluid, said tubes (4) being arranged in such a way as to accommodate the said energy-reserve unit (100), said tubes (4) comprising at least one canal for the circulation of said fluid and at least one canal (24) storing the phase-change material, said circulation canal or canals and said storage canal or canals (24) being configured to allow an exchange of heat between said fluid and said phase change material.

Description

Heat exchanger, in particular for the thermal regulation of a power reserve unit, and assembly formed of said heat exchanger and of said unit The present invention relates to a heat exchanger. It will find its applications, in particular, in the thermal regulation of a power reserve unit and more particularly the thermal regulation of battery packs or large single batteries, for example in the automotive field. It also relates to an assembly formed of said exchanger and said unit.

The thermal regulation of batteries and battery packs, particularly in the automotive field and even more particularly in the field of electric and hybrid vehicles, is an important point because if the batteries are subjected to temperatures that are too cold, their autonomy can decrease significantly and if they are subjected to too high temperatures, there is a risk of thermal runaway up to the destruction of the battery.

In order to control the temperature of the batteries, it is known to thermally regulate them by means of heat exchangers comprising a heat exchange bundle in direct contact with the batteries. A fluid flowing in the beam can thus absorb the heat emitted by the battery or batteries to cool them or, if necessary, bring heat to heat said batteries.

Fluid circulation is provided by a pump or compressor. In certain modes of operation of the vehicle, the pump or the compressor may be at a standstill, in particular with a view to reducing their energy consumption. The circulation of the fluid in the exchanger is then reduced or even stopped, which limits or even prevents the thermal regulation of the batteries. To remedy this, the licensee has already contemplated using a phase change material to perform energy storage in a thermal regulation circuit. Due to its latent heat and depending on the phase change involved, such a material makes it possible to continue the absorption of calories to continue a cooling or the return of calories to continue a heating, while the fluid of the thermal regulation circuit can not more or more sufficiently provide such functions. The use of a phase change material thus allows energy savings through optimized management of the consumption of the compressor or the pump, which generates an increase in autonomy for the electric vehicles or fuel economy, thus a reduction in C02 emissions, for thermal vehicles.

However, the configuration of the exchangers and the location of the phase-change material in the proposed devices are not compatible with the thermal regulation of batteries and still have drawbacks.

One of the aims of the invention is to at least partially overcome the disadvantages of the prior art. The present invention relates in this sense to a heat exchanger, in particular for the thermal regulation of a power reserve unit, said exchanger comprising a heat exchange bundle provided with tubes for circulating a fluid, said tubes being arranged to receive said energy reserve unit, said tubes comprising at least one circulation channel of said fluid and at least one storage channel of a phase change material, said at least one circulation channel and said at least one storage channels being configured to allow heat exchange between said fluid and said phase change material.

In this way, an exchanger is available which makes it possible to use a phase change material to participate in the thermal regulation of batteries and this particularly effective since the phase change material is close to the element to be cooled or heated. Indeed, it is inside the tubes of the heat exchanger with which the battery or batteries are in contact and can therefore exchange heat directly therewith without passing through the fluid. In addition, the location of the phase-change material inside the tubes of the exchanger makes it possible to protect it.

According to other features of the invention that can be taken together or separately:

said tubes are extruded tubes,

said channels are located parallel to one another,

said circulation channels are in greater number than the storage channels,

the storage channel or channels are located along longitudinal edges of said tubes,

the one or more circulation channels are located between said storage channels,

said storage channels are open,

said exchanger comprises one or more collectors provided with tube introduction orifices,

the collector or collectors comprise strips extending across said orifices so as to close said storage channels,

said tubes are pinched at the end of said storage channels in order to seal said storage channels,

said phase-change material has a latent heat of between 100 and 300 kJ / kg,

the tubes are configured to allow the use of a refrigerant as a fluid circulating in the circulation channels and said phase-change material has a phase change temperature of between 9 ° C. and 13 ° C.,

the tubes are configured to allow the use of a coolant as a fluid circulating in the circulation channels and said material to change phase has a phase change temperature of between 20 ° C and 25 ° C.

The invention also relates to an assembly comprising at least one exchanger as described above and at least one energy reserve unit.

According to one aspect of the invention, said energy reserve unit comprises at least one electric battery. Other features and advantages of the invention will emerge more clearly on reading the following description, given by way of illustrative and nonlimiting example, and the appended drawings among which:

FIG. 1 schematically shows a perspective view of a heat exchanger according to the invention,

FIG. 2 schematically shows an elevational view of an assembly of a heat exchanger and a power reserve unit, according to the invention,

FIG. 3 shows in cross-sectional view a tube of a heat exchanger according to the invention,

FIG. 4 shows in side view a portion of a collector of a heat exchanger according to the invention.

Figure 5 is a sectional view from the lines V-V illustrated in Figures 3 and 4 of said tube and said collector assembled together in an exchanger according to the invention. The identical elements in the different figures bear the same references.

As shown in FIG. 1, the invention relates to a heat exchanger 1. Said exchanger 1 comprises a heat exchange bundle 2 provided with tubes 4 for circulating fluid, in particular a refrigerant. It may be, for example, fluids known as R134a, R744 or 123YF. It could still be a heat transfer fluid such as water containing antifreeze, especially glycol. The exchanger 1 allows a heat exchange between said fluid and the external medium.

Said tubes 4 are preferably flat. This means that it has at least one large planar face 6, here two large flat faces 6, opposite and parallel, connected by short sides 8. Said tubes 4 are, for example, arranged parallel to each other so that the beam is formed of a single row of tubes 4. In other words, the flat faces 6 of the tubes 2 are arranged in two parallel planes so that the beam 2 can be considered as having a first large face 12, greater, substantially plane, and a second large face, lower 13, substantially flat and parallel to the upper face, the space between said large faces corresponding to the thickness e tubes (see Figure 3). Said tubes are here distributed in pairs, spaced apart from each other. Said heat exchanger further comprises collectors 10, arranged at each longitudinal end of the tubes 4. Said collectors are here of tubular form, of substantially round section. Said collectors 10 are provided with orifices 14 for introducing the tubes 4. Said tubes 4 open at their ends into said collectors 10 so that the fluid circulates between the tubes 4 and the collectors 10.

Said heat exchanger further comprises here gripping flanges 16. It also comprises fluid inlet and / or outlet flanges, not shown, in one and / or the other of the manifolds 10 so as to allow the circulation of said fluid in the exchanger 1.

Said exchanger is formed, for example, by brazing its elements, in particular collectors 10 and tubes 4, advantageously provided in aluminum and / or aluminum alloy. As illustrated in FIG. 2, said exchanger 1 is more particularly intended for the thermal regulation of a power reserve unit 100. By energy reserve unit 100 is meant a set of cells electrically connected to one another and forming a battery pack, or a single large battery.

According to the invention, said tubes 4 are arranged to receive said battery or batteries, in particular on one of said large faces 6 of the tubes 4. In other words, said exchanger 1 is configured to receive said battery or batteries on the one of the large faces of the beam 2, here the upper face 12.

As illustrated in FIG. 3, according to the invention, said tubes 4 comprise at least one channel 22 for circulating said fluid and at least one channel 24 for storing a phase-change material 26. The exchanger thus makes it possible both heat exchange between the battery or batteries and the fluid flowing in the exchanger and, particularly in the absence of such fluid circulation, heat exchange between the battery or batteries and said material to phase change 26.

The one or more circulation channels 22 and the one or more storage channels 24 are further configured to allow heat exchange between said fluid and said phase change material. During the fluid flow, said phase change material can then evacuate calories in the fluid to be operational again in a next phase of stopping the flow of fluid.

Thus, the phase-change material 26 makes it possible to cool and / or heat up the energy reserve unit for a certain period of time even if the fluid no longer circulates in the tubes 4, and this is repeated so long as the phases stopping the flow of the fluid are separated sufficiently long intervals to allow the phase change material to recover its properties during fluid circulation phases. In addition and always thanks to the invention, the phase-change material 26 is placed under optimized heat exchange conditions with both the battery (s) and with the fluid circulating in the heat exchanger, due to their proximity. It is thus possible to benefit even more advantageously than with the state of the art of the possibilities offered by the phase change material in terms of reducing the energy consumption of the pumps or compressors used to drive said fluid. .

Said tubes 4 are, for example, extruded tubes and in which the channels 22, 24 are derived from the extrasion. Said channels are advantageously located parallel to each other. They are separated by partitions 28.

Said circulation channels 22 and storage 24 are preferably of identical section. Said circulation channels are then in greater number than the storage channels 24 so that an internal volume of the tube intended to contain storage material is less than the internal volume of the tube intended for the circulation of the fluid, for example in a ratio of 1 to 2 to a ratio of 1 to 5. There are here two storage channels 24 for six circulation channels 22, substantially a ratio of 1 to 3 volumes mentioned above.

The one or more storage channels 24 are located, for example, along longitudinal edges of said tubes, as shown schematically in FIG. 1 by dotted lines. In other words, the one or more circulation channels 22 are located between said storage channels 24.

Due to the extrusion of the tubes 4, said storage channels 24 open at the end of said tubes 4. That being so, said ends of said storage channels 24 are sealed in order to prevent leakage of material to change phase 26 in the exchanger. For this, according to the example illustrated in Figures 4 and 5, the one or more collectors 10 comprise strips 30 extending across said orifices 14 so as to close said storage channels. Said strips 30 are obtained, in particular, during the stamping of the orifices 14. In FIG. 4, the circulation channels 22 have been schematically illustrated so as not to weigh down the figure.

Here, said orifices 14 has an oblong shape corresponding to a cross section of said tubes 4. Said orifices 14 are surrounded by collar 18, oriented towards the inside of the collectors 10. Said collars 18 facilitate the introduction of the tubes 4 into the orifices 14 and promotes the brazing of said tubes 4 on the collector 10.

Said strips 30 are disposed at the longitudinal ends of the orifices 14 opposite the storage channels 24. Said strips 30 form here an uncut bottom of the collars 18 in continuity of material with a radius 20 of said collars 18, said spoke 20 being indicated by a dashed line in FIG. 4. In other words, said tubes 4 open into said collectors 10 only at a zone 32 of said insertion orifice 14, said zone 32 being situated between the bars 30, in the extension of the circulation channels 22 and illustrated in dashed lines in FIG. 5. In a variant that is not illustrated, said tubes are gripped at the end of said storage channels in order to ensure their closure and the confinement of said storage material in the tubes. The use of strips is not necessary and the open area of said communication port is substantially identical to the cross section of the tubes.

The phase change material is chosen, for example, from materials with organic phase change, inorganic or vegetable origin.

Said phase change material has, for example, a latent heat of between 100 and 300 kJ / kg. For exchangers operating with a fluid refrigerant, said phase change material may have a phase change temperature of between 9 ° C and 13 ° C. For exchangers operating with a heat transfer fluid, said phase change material may have a phase change temperature of between 20 ° C and 25 ° C.

In extruded tubes having a size compatible with the intended application and channels of corresponding size given the thicknesses of material to be preserved, it will be possible to store 200 to 300 g of liquid phase change material. This provides about 70 seconds of storage for a limited temperature increase of 8 ° C to 15 ° C, after 180 seconds of charging at 8 ° C, which may go as far as to imply a saving of energy (electric or fuel) of the operation of the thermal control system, in cooling mode, by 30%.

Claims

Heat exchanger (1), in particular for the thermal regulation of a power reserve unit (100), said heat exchanger (1) comprising a heat exchange bundle (2) provided with tubes (4) for the circulation of heat a fluid, said tubes (4) being arranged to receive said energy reserve unit (100), said tubes (4) comprising at least one channel (22) for circulating said fluid and at least one channel (24); ) for storing a phase change material (26), said at least one circulation channel (22) and said one or more storage channels (24) being configured to allow heat exchange between said fluid and said change material phase (26).

Heat exchanger according to claim 1 wherein said tubes (4) are extruded tubes.

Heat exchanger according to any one of the preceding claims wherein said channels (22, 24) are located parallel to each other.

Heat exchanger according to any one of the preceding claims wherein said circulation channels (22) are greater in number than the storage channels (24).

A heat exchanger according to any one of the preceding claims wherein the at least one storage channel (24) is located along longitudinal edges of said tubes (4).

6. Heat exchanger according to any one of the preceding claims wherein the one or more circulation channels (22) are located between said storage channels (24).

7. Heat exchanger according to any one of the preceding claims wherein said storage channels (24) are through.

8. Heat exchanger according to any one of the preceding claims comprising a collector or collectors (10) provided with orifices (14) for introducing the tubes.

9. Heat exchanger according to the preceding claim wherein said one or more collectors (10) comprise strips (30) extending across said orifices (14) so as to close said storage channels (24).

10. Heat exchanger according to any one of claims 1 to 6 or 8 wherein said tubes (4) are clamped at the end of said storage channels (24) to ensure a closure of said storage channels (24).

An exchanger according to any one of the preceding claims, wherein said phase change material (26) has a latent heat of between 100 and 300 kJ / kg.

An exchanger according to any one of the preceding claims, wherein the tubes are configured to allow the use of a refrigerant as a fluid flowing in the circulation channels and said phase change material (26) has a phase change temperature between 9 ° C and 13 ° C.

13. Exchanger according to any one of claims 1 to 11, wherein the tubes are configured to allow the use of a heat transfer fluid as a fluid flowing in the circulation channels and said phase change material (26). has a phase change temperature of between 20 ° C and 25 ° C.

14. Assembly comprising at least one exchanger (1) according to any one of the preceding claims and at least one energy reserve unit (100).

15. An assembly according to the preceding claim wherein said energy storage unit (100) comprises at least one electric battery.