FR3060104A1 - THERMAL DEVICE WITH TUBULAR THERMAL EXCHANGE ELEMENT - Google Patents

Abstract

The present invention relates to a thermal device for a motor vehicle comprising a fluid circulation duct (2) and a heat exchange element (3) within the fluid circulation duct (2), the heat exchange element ( 3) comprising: - an outer tubular casing; an inner tubular casing; the inner tubular envelope delimiting inside a fluid circulation space, the outer tubular casing and the inner tubular casing delimiting between them a receiving space, the heat exchange element (3) further comprising a phase change material filling the receiving space.

Description

Holder (s): VALEO THERMAL SYSTEMS Simplified joint-stock company.

Extension request (s)

Agent (s): VALEO SYSTEMES THERMIQUESTHS.

THERMAL DEVICE WITH TUBULAR THERMAL EXCHANGE ELEMENT.

FR 3 060 104 - A1 (5 /) The present invention relates to a thermal device for a motor vehicle comprising a fluid circulation duct (2) and a heat exchange element (3) within the fluid circulation duct (2 ), the heat exchange element (3) comprising:

- an outer tubular casing;

- an internal tubular envelope;

the internal tubular envelope delimiting inside a fluid circulation space, the external tubular envelope and the internal tubular envelope delimiting between them a receiving space, the heat exchange element (3) further comprising a phase change material filling the receiving space.

THERMAL DEVICE WITH THERMAL EXCHANGE ELEMENT

TUBULAR

The present invention relates to the field of thermal devices for motor vehicles. More particularly, the present invention relates to the field of thermal devices comprising a fluid circulation conduit.

A motor vehicle is subjected to highly variable environments during driving; it can pass from a cold air zone to a hot air zone, be subjected to bad weather such as rain, gusts of winds, etc. The punctual and chaotic nature of these phenomena makes thermal management of the motor vehicle difficult and sometimes causes mechanical damage.

In order to mitigate these harmful effects for the motor vehicle and to improve its thermal performance, it is possible to integrate inside the heat exchangers a phase change material. An example of a heat exchanger, in particular cooling radiators, typically includes an exchange bundle. This exchange bundle comprises a stack of plates or tubes alternately forming circulation ducts for the air to be cooled and channels for the circulation of heat transfer fluid, in particular engine coolant. The heat exchange between the plates or tubes and the charge air is carried out in part by means of turbulators. The bundle is enclosed in a receptacle which generally has the shape of a straight and hollow cylinder, most often of rectangular base, connected at one of its open ends to an inlet air box and to the other to an outlet air box (configuration in I, that is to say that the air to be cooled follows a straight line path); or at one of its ends open to an inlet and outlet air box and to the other to a deflection air box (U-shaped configuration, i.e. the air to be cooled follows a bent path in order to come out appreciably collinear to its direction of entry)

More particularly, an air box typically comprises a casing having a longitudinal axis, a bottom and two sides extending from the bottom on the same side of it so as to give a U-shaped cross section. It also includes a port inlet and / or a coolant outlet port. In most cases, the space between the sides and the bottom is only intended to receive the heat transfer fluid.

However, the idea came up to use this space to install a phase change material in it. For example, document FR3006044 describes a heat exchanger with a phase change material encapsulated in polymer beads in its inlet and outlet water boxes. This arrangement of the phase change material is simple to implement. However, it has the disadvantage of producing fairly high pressure drops and requires, inside the manifolds, the use of grids or foam to retain the phase change material.

An objective of the present invention is to overcome at least one of the drawbacks of the state of the art described above, in particular to mitigate the harmful effects of punctual and chaotic changes in the environments to which the motor vehicle is subjected, to improve its thermal performance, and / or to avoid the production of pressure drop.

For this, the present invention provides a thermal device for a motor vehicle comprising a fluid circulation conduit and a heat exchange element within the fluid circulation conduit, the heat exchange element comprising:

- an outer tubular casing;

- an internal tubular envelope;

the internal tubular envelope delimiting inside a fluid circulation space, the external envelope and the internal envelope delimiting between them a receiving space, the heat exchange element further comprising a phase change material filling the reception area.

Such a solution makes it possible to optimize the integration of the phase change material in the thermal device by avoiding providing phase change material directly in the manifolds. Furthermore, the present invention provides two heat exchange surfaces for each heat exchange element disposed in the thermal device, significantly increasing the overall exchange surface between the phase change material and the heat transfer fluid which circulates around and at inside the heat exchange element. In addition, given the low thermal conductivity of phase change materials, the thickness thereof in a heat exchange element as provided in the present invention is reduced, thus facilitating the transfer of energy; the phase change material being able to store and / or return energy through two surfaces, also creating two solid / liquid interfaces within the phase change material.

Other optional and non-limiting characteristics are described below.

The outer tubular casing and the inner tubular casing can be made of polymer, preferably polycarbonate, polyester or polyamide. Alternatively, the outer tubular casing and the inner tubular casing can be made of metal, in particular aluminum.

The outer tubular casing may have an outside diameter of between 1 and 10 mm.

The outer tubular casing and the inner tubular casing can be separated by a distance between 50 µm and 20 mm.

The phase change material can be chosen from the group consisting of a fatty acid of vegetable origin, a fatty alcohol of vegetable origin, a paraffin, a hydrated salt and their mixtures.

The phase change material may have a phase change temperature between 45 and 110 ° C. Preferably, the phase change temperature is between 45 and 55 ° C. Alternatively, the phase change temperature is between 80 and 110 ° C.

The ends of the inner and outer tubular casings can be sealed with the same material as that forming the inner and outer tubular casings, by a rivet or by crimping, leaving an opening towards the passage space of the same diameter as the latter.

The thermal device can be a heat exchanger or a thermal battery. More particularly, the thermal device can be a heat exchanger further comprising an exchange bundle composed of a superposition of circulation conduits as defined above, and in which one or more heat exchange elements are arranged at the interior of the exchange beam circulation conduits so that the longitudinal direction of the heat exchange elements and that of the circulation conduits are collinear and so as to allow the passage of a first heat transfer fluid around the elements heat exchange and that of a second heat transfer fluid in the fluid circulation space. In addition, the first heat transfer fluid and the second heat transfer fluid may be identical or different fluids. In addition or alternatively, the heat exchanger is that of a low temperature radiator. Alternatively, the heat exchanger may be that of a high temperature radiator.

The thermal device may further comprise a bundle casing for housing the exchange bundle and a manifold for coupling the bundle casing with another element of the heat exchanger, the manifold having a grid for holding the interchange members. thermal.

Alternatively, the thermal device can be a thermal battery comprising an enclosure with an inlet and an outlet for heat transfer fluid, and an exchange bundle housed in the enclosure and comprising layers formed by the heat exchange elements, the elements d 'heat exchange forming a sheet being mutually parallel and separated without contact with each other.

Other objectives, characteristics and advantages will appear on reading the detailed description which follows with reference to the drawings, among which:

- Figure 1 is a three-quarter view in partial section of an example of a thermal device according to the present invention;

- Figure 2 is a three-quarter view in partial section of another example of a thermal device according to the present invention;

- Figure 3 is a partial front view of circulation conduits and heat exchange elements in a thermal device according to the present invention, in particular the thermal device of Figure 1; and

- Figure 4 is a cross-sectional view of a heat exchange element according to the present invention surrounded by a heat transfer fluid.

A thermal device for a motor vehicle according to the present invention will be described below with reference to FIGS. 1 to 4.

Such a thermal device 1 comprises a fluid circulation conduit 2 and a heat exchange element (EET) 3 within the fluid circulation conduit 2.

The fluid circulation conduit 2 can have several forms known to those skilled in the art. For example, the fluid circulation duct 2 can be a tube, in particular a tube whose cross section has the shape of a circle (FIG. 2) or of an oval with two axes of symmetries perpendicular to each other. 'other. In particular, for the oval with two axes of symmetry, it comprises two half-arcs of circle symmetrical to one another through a first of the axes of symmetries, the open parts facing each other, and connected one to the other. the other so as to form a closed curve. However, other forms can also be provided.

The EET 3 comprises an external tubular casing 31, an internal tubular casing 32 and a phase change material (PCM) 35. The internal tubular casing 32 delimits inside ΓΕΕΤ a fluid circulation space 33, in particular for a heat transfer fluid. The outer tubular casing 31 and the inner tubular casing 32 define between them a receiving space 34, in particular of the PCM 35 which fills it.

Thus, as illustrated in FIG. 4, it is possible to circulate a fluid around and inside 1ΈΕΤ 3 so that two solid-liquid interfaces 361, 362 are formed inside the PCM 35. Each of these two solid-liquid interfaces 361, 362 move towards the center of the PCM 35 when ΓΕΕΤ 3 is in energy storage mode (temperature of the surrounding fluid 1ΈΕΤ 3 and that inside is at a temperature higher than the change temperature of PCM phase 3).

In comparison, in an EET comprising only one external tubular envelope forming a receiving space filled with a PCM, a single solid-liquid interface is present inside the PCM so that a longer time is necessary for that the whole PCM goes from liquid to solid or vice versa.

In addition, it is possible for the PCM 35 to store and restore thermal energy at the same time, in particular when the fluid surrounding ΓΕΕΤ 3 and the one inside ΓΕΕΤ 3 are at different temperatures. For example, if a first fluid circulating inside ΓΕΕΤ 3 is at a higher temperature than a second fluid circulating outside ΓΕΕΤ 3, the PCM 35 stores thermal energy from the first fluid and restores this energy to the second fluid.

The storage and release of thermal energy can of course be done in the other direction when the second fluid is at a higher temperature than the first fluid.

In addition, the use of EET 3 having a fluid circulation space 33 has the additional advantage of limiting the pressure drop of the thermal device 1, which is beneficial for the operation of a cooling loop in particular. Thus, certain elements of the thermal device 1 can be dimensioned downwards, such as a pump for example. Therefore, the power consumption can be reduced for example.

Each of the external and internal tubular casings 31, 32 can be made of polymer, preferably of polycarbonate, polyester or polyamide. The thickness of the envelopes is in this case preferably between 100 and 300 μm. Alternatively, each of the external and internal tubular envelopes 31, 32 can be made of metal, in particular aluminum. The use of metal compared to the polymer has the advantage of obtaining casings of smaller thickness while guaranteeing sufficient mechanical strength, in particular between 50 and 100 μm. This smaller thickness allows more efficient heat transfer from the fluid surrounding EET 3 or into EET 3 and PCM 35. Furthermore, metal is a better conductor of heat than polymeric materials, further improving heat transfer.

Preferably, the external and internal tubular casings 31, 32 of the EET are coaxial. In order to guarantee this coaxiality, the EET 3 can also comprise spacers 37 in the receiving space 34 and arranged at the ends of the external and internal tubular envelopes and / or distributed along the external and internal tubular envelopes 31, 32.

The outer tubular casing 31 can have an outside diameter between 1 and 20 mm, preferably between 3 and 10 mm, although in general this limitation depends on the application. In particular in a heat exchanger application, this outside diameter is limited by the conduits of the exchange bundle (see below), and in the case of a thermal battery, the only limit is the acceptable battery space.

The external tubular envelope 31 and the internal tubular envelope 32 can be separated by a distance (space between these two envelopes) of between 50 μm and mm, preferably between 1 and 10 mm, more preferably between 1 and 3 mm . For example, the outer tubular casing 31 has an outside diameter of 4 mm and the space between the outer tubular casing and the inner tubular casing is 2 mm.

The length of 1ΈΕΤ can be easily adapted to the application of the thermal device. In the case of a heat exchanger, 1ΈΕΤ may have a length substantially equal to the length of the conduits of the heat exchanger exchange bundle, for example between 400 and 600 mm. In the case of a thermal battery, the only limit is the acceptable size of the battery, for example between 100 and 300 mm.

PCM 35 can be chosen from the group consisting of a fatty acid of vegetable origin, a fatty alcohol of vegetable origin, a paraffin, a hydrated salt and their mixtures.

The PCM 35 can have a phase change temperature between 45 and 110 ° C. Preferably, the phase change temperature is between 45 and 55 ° C, for example when the thermal device is a low temperature radiator. Alternatively, the phase change temperature is between 80 and 110 ° C, for example when the thermal device is a high temperature radiator.

The PCM 35 can have a latent heat of phase change greater than 200 kJ / kg preferably, greater than 280 kJ / kg. Latent heat of phase change guarantees a large capacity of energy storage.

The ends of the internal and external tubular envelopes 31, 32 can be sealed with the same material as that forming the external and internal tubular envelopes 31, 32, or by a rivet or by crimping, leaving an opening towards the circulation space fluid 33 of the same diameter as the latter. In particular, plugs also forming spacers can be used at the ends of the external and internal tubular casings 31, 32, and having a central orifice opening into the fluid circulation space 33.

In general, ΓΕΕΤ 3 can be produced in the following ways:

- the external and internal tubular casings 31, 32 are manufactured separately and then assembled one inside the other with spacers 37 to keep them at a distance, preferably coaxial;

- A double-walled tube is manufactured, comprising the external and internal tubular envelopes 31, 32 and spacers 37 integrally formed with the external and internal tubular envelopes 31, 32; or

- the internal tubular casing 32 is first manufactured, then used to manufacture the external tubular casing 31, for example by extrusion, in this case, it is possible to coextrude at the same time the external tubular casing 31 and the PCM 35 in solid form using the internal tubular casing 32 as a support for drawing the extrusion.

The thermal device 1 can be a heat exchanger or a thermal battery. In the case of a heat exchanger, the fluid circulation duct 2 can be a heat exchanger tube or an assembly of plates for a heat exchanger. In the case of a thermal battery, the fluid circulation duct 2 can be the enclosure (housing or casing) of the thermal battery.

More particularly, the thermal device 1 can be a heat exchanger further comprising an exchange bundle composed of a superposition of circulation conduits as defined above, and in which one or more EETs 3 are arranged at the interior of the fluid circulation conduits 2 of the exchange bundle so that the longitudinal direction of the EETs 3 and that of the fluid circulation conduits 2 are collinear and so as to allow the passage of a first heat transfer fluid around the EET 3 and that of a second heat transfer fluid in the fluid circulation space 33. In addition, the first heat transfer fluid and the second heat transfer fluid may be identical or different fluids. In addition or alternatively, the heat exchanger is that of a low temperature radiator. Alternatively, the heat exchanger may be that of a high temperature radiator.

The thermal device 1 may further comprise a bundle casing for housing the exchange bundle and a manifold for coupling the bundle casing with another element of the thermal device, the manifold having a grid for holding the EETs.

3.

Alternatively, the thermal device 1 can be a thermal battery comprising an enclosure with an inlet and an outlet for heat transfer fluid, and an exchange bundle housed in the enclosure and comprising sheets formed by the EETs 3, the EETs 3 forming a sheet being parallel to each other and separated without contact with each other.

Claims (18)

Claims 1. Thermal device (1) for a motor vehicle comprising a fluid circulation conduit (2) and a heat exchange element (3) within the fluid circulation conduit (2), the heat exchange element ( 3) including: - an outer tubular casing (31); - an internal tubular casing (32); the internal tubular casing (32) delimiting inside a fluid circulation space (33), the external tubular casing (31) and the internal tubular casing (32) delimiting between them a receiving space (34) , the heat exchange element (3) further comprising a phase change material (35) filling the receiving space (34). 2. Thermal device (1) according to claim 1, wherein the outer tubular casing (31) and the inner tubular casing (32) are made of polymer, preferably polycarbonate, polyester or polyamide. 3. Thermal device (1) according to claim 1, wherein the outer tubular casing (31) and the inner tubular casing (32) are made of metal, in particular aluminum. 4. Thermal device (1) according to one of claims 1 to 3, wherein the outer tubular casing (31) has an outer diameter between 1 and 20 mm. 5. Thermal device (1) according to one of claims 1 to 4, wherein the outer tubular casing (31) and the inner tubular casing (32) are separated by a distance between 50 pm and 20 mm. 6. Thermal device (1) according to one of claims 1 to 5, in which the phase change material (35) is chosen from the group consisting of a fatty acid of vegetable origin, a fatty alcohol of origin vegetable, paraffin, hydrated salt and mixtures thereof. 7. A thermal device (1) according to one of claims 1 to 6, wherein the phase change material (35) has a phase change temperature between 45 and 110 ° C. 8. A thermal device (1) according to claim 7, wherein the phase change temperature (35) is between 45 and 55 ° C. 9. A thermal device (1) according to claim 7, wherein the phase change temperature (35) is between 80 and 110 ° C. 10. Thermal device (1) according to one of claims 1 to 9, in which the ends of the external and internal tubular envelopes (31, 32) are sealed with the same material as that forming the external and internal tubular envelopes (31, 32), by a rivet or by crimping, leaving an opening towards the passage space of the same diameter as the latter. 11. Thermal device (1) according to one of claims 1 to 10, wherein the thermal device (1) is a heat exchanger or a thermal coil. 12. A thermal device (1) according to claim 11, in which the thermal device (1) is a heat exchanger further comprising an exchange bundle composed of a superposition of fluid circulation conduits (2) as defined. in claim 1, and in which one or more heat exchange elements (3) are arranged inside the fluid circulation conduits (2) of the exchange bundle so that the longitudinal direction of the elements d heat exchange (3) and that of the fluid circulation conduits (2) are collinear and so as to allow the passage of a first heat transfer fluid around the heat exchange elements (3) and that of a second heat transfer fluid in the fluid circulation space (33). 13. A thermal device (1) according to claim 12, wherein the first heat transfer fluid and the second heat transfer fluid are identical or different fluids. 5 14. A thermal device (1) according to claim 12 or claim 13 in combination with claim 8, wherein the heat exchanger is that of a low temperature radiator. 15. A thermal device (1) according to claim 12 or claim 13 in combination with claim 9, wherein the heat exchanger is that of a high temperature radiator. 16. Thermal device (1) according to one of claims 12 to 15, further comprising a bundle housing for housing the exchange bundle and a collector for 15 couple the harness casing with another element of the heat exchanger, the manifold having a grid for holding the heat exchange elements. 17. A thermal device (1) according to claim 11, wherein the thermal device is a thermal battery comprising an enclosure with an inlet and a 20 heat transfer fluid outlet, and an exchange bundle housed in the enclosure and comprising plies formed by the heat exchange elements, the heat exchange elements forming a ply and being parallel to each other and separated without contact with each other with the others. 2/2