FR3063806A1 - THERMAL TRANSFER DEVICE AND SPATIAL DEVICE COMPRISING SUCH A THERMAL TRANSFER DEVICE - Google Patents

Abstract

A heat transfer device (2) capable of transferring heat comprising a housing (5) having a first main wall (12) and a second main wall (14), said housing (5) having an internal cavity (6) sealed, a liquid (8) contained in the internal cavity (6) and a mixer (10) adapted to put said liquid in motion, the thermal transfer device (2) being adapted to be switched between a first state and a second state in which the liquid is in motion and convectively transferring heat between the first main wall and the second main wall, the thermal conductance between the first main wall and the second main wall in the first state being four less than the thermal conductance between the first main wall and the second main wall in the second state.

Description

© Publication number: 3,063,806 (use only for reproduction orders)

©) National registration number: 17 52027 ® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY

COURBEVOIE © Int Cl ⁸ : F28 F13 / 12 (2017.01), B 64 G 1/22

A1 PATENT APPLICATION

©) Date of filing: 13.03.17. © Applicant (s): AIRBUS DEFENSE AND SPACE SAS ©) Priority: Simplified joint stock company - FR. @ Inventor (s): WALKER ANDREW. ©) Date of public availability of the request: 14.09.18 Bulletin 18/37. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ® Holder (s): AIRBUS DEFENSE AND SPACE SAS related: Joint stock company. ©) Extension request (s): © Agent (s): CABINET PLASSERAUD.

THERMAL TRANSFER DEVICE AND SPACE MACHINE COMPRISING SUCH A THERMAL TRANSFER DEVICE.

FR 3 063 806 - A1 kü / y The invention relates to a thermal transfer device (2) capable of transferring heat comprising a housing (5) having a first main wall (12) and a second main wall (14), said housing (5) comprising an internal cavity (6) sealed, a liquid (8) contained in the internal cavity (6) and a mixer (10) suitable for setting said liquid in motion, the heat transfer device ( 2) being suitable for being switched between a first state and a second state in which the liquid is in motion and transfers by convection of heat between the first main wall and the second main wall, the thermal conductance between the first main wall and the second main wall in the first state being four times lower than the thermal conductance between the first main wall and the second main wall in the second state.

Thermal transfer device and spacecraft comprising such a thermal transfer device

The present invention is in the field of heat transfer devices. The present invention finds applications in numerous technical fields which require controlled heat transfers and in particular in the aerospace field and in particular for satellites in geostationary orbit.

In fact, due to the earth's movement of revolution around the sun, the different faces of a geostationary satellite do not receive the same amount of solar radiation during an orbit. In particular the East and West faces are alternately exposed to the sun is in the shade, which produces a variable thermal environment for the satellite, sometimes very hot, sometimes very cold. Consequently, the East and West faces are generally thermally isolated from the satellite. The dissipation of the heat dissipated by the satellite equipment is then essentially carried out by the north and south walls, which limits the satellite's thermal rejection capacity to the capacity of the north and south radiators. On the other hand, the dimensioning of the radiators is made so that the equipment remains at a temperature lower than that compatible with their proper functioning, in the most unfavorable case, which is often called the "worst hot case". This “worst case” design can then lead to excessive cooling of the equipment, especially when it is not in operation, at a temperature below the minimum temperature that it can withstand. This makes it necessary to have heating devices to keep the equipment at a sufficient temperature in the more unfavorable case which is often called the "worst cold case". In addition, the satellite's solar generator must be able to supply the necessary electric power, which is not necessarily available, especially during the electric transfer phase, where the equipment of the payload is cut and the power reserved for the thrusters. electrics ensuring the transfer to the geostationary orbit.

In the usual case the transport of heat to the radiators is done by heat pipes. These heat pipes operate in a completely passive and bidirectional manner so that the problem is particularly critical because the heat pipe will continue to provide heat transfer between the radiators and without the possibility of interrupting it.

The object of the present invention is to provide a controllable, light and reliable heat transfer system which makes it possible to solve the above drawbacks.

To this end, the subject of the invention is a heat transfer device capable of transferring heat between a first object and a second object, comprising a housing having a first main wall and a second main wall, the first main wall being intended to be in direct thermal contact by conduction with said first object, the second main wall being intended to be in direct thermal contact by conduction with said second object, said housing comprising an internal cavity closed in a sealed manner, a liquid contained in the cavity internal and a mixer capable of setting said liquid in motion, the thermal transfer device being capable of being switched between a first state in which the liquid stagnates and a second state in which the liquid is in motion and transfers by forced convection of heat between the first main wall and the second main wall, the thermal conductance between the first main wall ipale and the second main wall when the transfer device is in the first state being four times lower than the thermal conductance between the first main wall and the second main wall when the transfer device is in the second state.

Advantageously, the heat transfer device can be a good heat exchanger in one state and a good thermal insulator in the other state. When coupled with other means of thermal transfer, it can thus function as a thermal switch for this means of transfer.

Advantageously, the heat transfer device is bidirectional. It is therefore compatible with other bi3063806 directional heat transfer means such as heat pipes. Thus, the heat transport can be carried out either from the heat pipe to the second main wall of the housing or from the second main wall of the housing to the heat pipe.

Advantageously, this heat transfer device has a low mass and consumes little electrical energy.

Advantageously, this heat transfer device has a small footprint.

According to particular embodiments, the heat transfer device comprises one or more of the following characteristics:

- The transfer device further comprises said first object and in which the first object is a heat pipe.

- The transfer device further comprises said second object and in which the second object is a heat pipe. According to one embodiment, the first main wall is in direct thermal contact with said heat pipe. According to another embodiment, at least one object from the first object and the second object is integrated into at least one wall from the first main wall and the second main wall.

- At least one wall from the first main wall and the second main wall has a flat outer face.

Advantageously, this planar wall promotes heat exchange with a flat object.

- The housing has the shape of a parallelepiped having a length, a width and a height, the height being the distance between the first main wall and the second main wall, and in which the height has a dimension twice less than said width .

- The fluid is a dielectric fluid and in which the mixer comprises at least two electrodes disposed at intervals from one another and immersed in the dielectric fluid, the electrodes and the fluid forming an electro-hydrodynamic system.

Advantageously, this planar shape limits the power required to drive the fluid and increases the exchange surface at constant volume.

- The electrodes extend in a plane parallel to the median plane of the main walls.

Advantageously, this type of mixer is reliable because it does not include mechanical parts which could wear out due to repeated contacts.

The mixer comprises a first support suitable for carrying at least two electrodes and a second support suitable for carrying at least two electrodes, the first and second supports being arranged one next to the other in the same plane parallel to a wall main, the at least two electrodes carried by the first support being supplied by a first voltage, the at least two electrodes carried by the second support being supplied by a second voltage, said second voltage being of sign opposite to the first voltage, the circulation of the fluid between the electrodes of the first support and the circulation of the fluid between the electrodes of the second support being in opposite directions.

The thermal conductance between the first main wall and the second main wall in the first state is less than 40 W / K / m ² and advantageously less than 8 W / k / m ² .

The thermal conductivity between the first main wall and the second main wall in the second state is greater than 250 W / K / m ² and advantageously greater than 800 W / k / m ² .

The mixer is a mechanical device for driving the liquid.

The subject of the invention is also a spacecraft comprising:

- a body having a North face, a South face opposite to the North face, an East face and a West face opposite to the East face;

- at least one radiator carried by at least one face among the North face, the South face, the East face or the West face,

- at least one dissipative device connected by a nominal heat transfer device to at least one radiator;

characterized in that the nominal thermal transfer device comprises at least one thermal transfer device according to the characteristics mentioned above, so as to allow a switchable thermal conductance between the dissipative equipment and the radiator according to the state of the device. Thermal transfer.

Alternatively, the spacecraft includes at least one redundant heat transfer device, a nominal heat pipe and a redundant heat pipe, and in which a main wall of the main transfer device and a main wall of the redundant transfer device is in thermal contact with said nominal heat pipe and said redundant heat pipe.

The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the figures in which:

- Figure 1 is a schematic sectional view of a thermal transfer device according to a first embodiment of the invention, of a first and a second object, the thermal transfer device being in a first state;

- Figure 2 is a schematic sectional view of the heat transfer device, the first and second objects as illustrated in Figure 1, the heat transfer device being in a second state;

- Figure 3 is a schematic sectional view of a heat transfer device according to a second embodiment of the invention;

- Figure 4 is a schematic sectional view of a heat transfer device according to a third embodiment of the invention;

- Figure 5 is a schematic sectional view of a heat transfer device according to a fourth embodiment of the invention;

- Figure 6 is a schematic sectional view of a heat transfer device according to a fifth embodiment of the invention;

- Figure 7 is a schematic perspective view of a spacecraft according to the present invention; and

- Figure 8 is a schematic perspective view of a portion of a spacecraft comprising two heat transfer devices mounted in redundancy.

Referring to Figure 1, the thermal transfer device 2 according to the invention is suitable for transferring or not transferring heat by forced convection between a first object 3 and a second object 4. It acts as a thermal switch .

The heat transfer device 2 can for example be mounted in a spacecraft or in any other device requiring control of a heat flow. The first 3 and the second 4 objects are then for example constituted by heat pipes, electronic components, support plates for these electronic components, equipment. Thus, FIG. 1 can for example represent a sectional view along the plane l-l of a thermal device and of two heat pipes of a part of a spacecraft as illustrated in FIG. 8.

According to the first embodiment of the invention illustrated in FIG. 1, the thermal transfer device 2 comprises a hollow housing 5 delimiting an internal cavity 6, a liquid 8 contained in the internal cavity 6 and a mixer 10 suitable for placing in movement of the liquid and cause an increase in thermal conduction between two parts of the housing 5.

The housing 5 is closed in a sealed manner.

In the embodiment of Figure 1, the housing 5 has a generally rectangular parallelepiped shape with a hollow appendage. It has a first main wall 12, a second main wall 14 opposite the first main wall and four side walls 16. The housing 5 has a length L, a width I and a height h, the height h being defined as the distance between the first main wall 12 and the second main wall 14.

Preferably, the housing 5 is flat. Thus, the housing 5 has a height of dimension twice less than its width I. Its first 12 and its second main walls are in thermal contact with the first 3 and the second 4 objects.

In this embodiment, advantageously, the first 12 and the second 14 main walls have a flat external face 17. This flatness promotes heat exchange with the first and the second objects.

In the embodiment shown in FIG. 1, the mixer 10 forms with the liquid an electro-hydrodynamic system 18. This electro-hydrodynamic system 18 comprises two electrodes 20 spaced from one another and immersed in the liquid. The liquid is a dielectric liquid. The liquid is able to transfer heat. An EHD device as described in patent application WO 2015/084238, could be used.

In the embodiment shown, the mixer 10 comprises an electronic processing unit 24 housed in appendix 22. The electronic processing unit 24 is suitable for receiving a control signal and for applying or not applying a voltage between the two electrodes 20 as a function of this control signal.

In operation, the heat transfer device 2 is a thermal switch capable of being switched between a state of low thermal conduction said first state, and a state of high thermal conduction said second state.

In the first state illustrated in Figure 1, no voltage is applied between the two electrodes 20. The liquid is stationary. The liquid stagnates. The heat transfer device acts as an insulator. The heat from the first object is not (or only slightly) transferred to the second object, even if the two objects have a very different temperature.

In the second state illustrated in Figure 2, a voltage is applied between the two electrodes 20. The liquid is driven in motion. If the first main wall has a temperature higher than the second main wall, heat is transferred from the first main wall 12 by convection to the second main wall 14. If the second main wall has a temperature higher than the first main wall, heat is transferred from the second main wall 12 by forced convection to the first main wall 14.

Advantageously, this system is thus bidirectional and can be combined with heat pipes or any other bidirectional heat transfer device, the combination remaining bidirectional.

Advantageously, according to the present invention, the thermal conductance between the first main wall 12 and the second main wall 14, when the heat transfer device is in the first state is four times lower than the thermal conductance between the first main wall 12 and the second main wall 14, when the heat transfer device is in the second state.

Preferably, the thermal conductance between the first main wall 12 and the second main wall 14 in the first state is less than 40 W / K / m ² and advantageously less than 8 W / k / m ² .

The thermal conductivity between the first main wall 12 and the second main wall 14 in the second state is greater than 250 W / K / m ² and advantageously greater than 800 W / k / m ² .

A heat transfer device 26 according to a second embodiment of the invention is illustrated in FIG. 3. This heat transfer device 26 is similar to the heat transfer device 2 according to the first embodiment of the invention except for the fact that a heat pipe 28 is integrated into the first main wall 12. The technical elements of the heat transfer device 26 according to the second embodiment identical to the technical elements of the heat transfer device 2 according to the first embodiment are referenced by the same references and will not be described a second time.

The integration of the heat pipe 28 into the first main wall promotes the transmission of heat from the heat-producing liquid contained in the heat pipe to the liquid contained in the internal cavity 6.

A heat transfer device 30 according to a third embodiment of the invention is illustrated in FIG. 4. The heat transfer device 30 according to the third embodiment of the invention will not be described in full, only the differences from the heat transfer device according to the first embodiment will be described. The technical elements of the heat transfer device 30 according to the third embodiment identical to the technical elements of the heat transfer device 2 according to the first embodiment are referenced by the same references and will not be described a second time.

In this embodiment, the two electrodes 20 are replaced by several pairs of identical electrodes. Each electrode having the form of a grid 32. The mixer 10 also comprises a support suitable for carrying the electrodes 32 so that they are superimposed on each other in the direction Y. The electrodes 32 extend in a plane (X, Z) parallel to the median plane of the main walls 12, 14. The electrodes are further spaced from each other by a free space e. Each pair of electrodes is supplied in parallel by the electronic processing unit 24. A device as described in FIG. 6 of patent application WO 2015/084238 could be used.

Preferably, the electrodes 32 extend over a surface less than the interior surface of the first main wall 12. Thus, a portion of the cavity 6 is not traversed by the electrodes and is intended for the return of fluid. Such an arrangement causes a displacement of the fluid in a loop tangent to the first 12 and to the second 14 main walls. A compromise has to be found between the surface of the electrodes in the form of a flat grid which must be maximized for the entrainment of the fluid and the remaining space which must be sufficient to ensure the return of the fluid while limiting the pressure drops.

The electronic processing unit 24 is capable of applying a voltage to each electrode so as to generate a potential difference between each pair of adjacent electrodes. The potential differences between each pair of adjacent electrodes of the support 34 are all of the same sign. A potential difference equal to the sum of the potential differences between each pair of adjacent electrodes is generated between the upper electrode and the lower electrode.

In operation, when the heat transfer device 30 is in the second state, the liquid is able to move in loops having a first portion of path T1 directed in a direction Y perpendicular to the electrodes, a second portion of path T2 curved according to a direction belonging to the plane of the second main wall, a third portion of path T3 in a direction opposite to the direction Y and a fourth portion of path T4 in a direction belonging to the plane of the first main wall.

A heat transfer device 42 according to a fourth embodiment of the invention is illustrated in FIG. 5. The heat transfer device 42 according to the fourth embodiment of the invention will not be fully described only the differences with respect to the heat transfer device according to the third embodiment will be described. The technical elements of the heat transfer device 42 according to the fourth embodiment identical to the technical elements of the heat transfer device 30 according to the third embodiment are referenced by the same references and will not be described a second time.

The heat transfer device 42 according to the fourth embodiment of the invention comprises a first support 44 carrying electrodes 32 and a second support 46 supporting electrodes 32. The second support 32 is disposed adjacent to the first support 44. embodiment, the supports 44, 46 and electrodes 32 occupy the entire internal surface of the housing 5.

The first 44 and the second 46 supports are identical to the support of the heat transfer device according to the third embodiment except that it has a lower number of electrodes in the example illustrated in FIG. 5.

The electronic processing unit 24 is capable of applying a first voltage U1 between the upper electrode and the lower electrode of the first support 44 and a second voltage U2 between the upper electrode and the lower electrode of the second support 46. The first voltage U1 is of opposite sign to the second voltage U2.

In operation, in the second state, the liquid 8 moves along a first path portion T1 which extends in the direction Y through the electrodes of the first support 44, a second path portion T2 along a direction parallel to the plane electrodes, a third path portion T3 which extends in the direction Y through the electrodes of the second support 46 and a fourth path portion T4 in a direction parallel to the plane of the electrodes.

A heat transfer device 48 according to a fifth embodiment of the invention is illustrated in FIG. 6. The heat transfer device 48 according to the fifth embodiment of the invention will not be described in full, only the differences from the heat transfer device according to the first embodiment will be described. The technical elements of the heat transfer device 48 according to the fifth embodiment identical to the technical elements of the heat transfer device 2 according to the first embodiment are referenced by the same references and will not be described a second time.

In this embodiment, the housing 50 has a flattened semispherical section. It has a length L which extends in the direction Z. In particular, the housing 50 has a cross section of elliptical shape. The housing has a first curved main wall 52 in thermal contact with a first object 3 and a second curved main wall 54 in thermal contact with a second object 4.

The liquid contained in the internal cavity 6 is not dielectric.

In this embodiment, the mixer 10 comprises a rotary actuator 54, a rotary shaft 56 and blades 60 mounted on the rotary shaft and driven in rotation by the rotary actuator 54. A magnetic stirrer could also be used.

In operation, the heat transfer device 48 is switched between a first state in which the rotary actuator 54 is not in operation and a second state in which the rotary actuator 54 is set in motion.

In the first state, the liquid stagnates, the thermal conduction between the first main wall 52 and the second main wall 54 is weak. In the second state, the rotary actuator 54 is put into operation. There is a heat transfer between the first main wall 52 and the second main wall 54.

As a variant, the mixer 10 comprises a blade capable of beating the liquid to mix it.

The heat transfer device according to the present invention can for example be mounted on a spacecraft 62 as illustrated in FIGS. 7 and

8.

With reference to FIG. 7, a spacecraft 62 of the geostationary satellite type is in the form of a parallelepipedic box delimiting an interior space 65 and an exterior space 66. This box always has the same face directed towards the Earth, this face being called the Earth face 68. The face opposite and parallel to the Earth face 68 is for its part called the anti-Earth face. It is not shown in Figure 7.

The face - X, also called the East face (not shown), and the face + X, also called the West face 74, are opposite faces, mutually parallel and perpendicular to the direction of movement of the spacecraft. Communication antennas 76 are generally fixed on the faces - X and + X.

The - Y face, also called the North face 78, and the + Y face, also called the South face 80, are two other sides of the body. They are opposite, parallel to each other and perpendicular to the North-South axis of the Earth.

A first main radiator 82, generally called the North radiator, is fixed to and extends on the face -Y 78. A second main radiator 84, generally called the South radiator, is fixed to and extends on the side + Y 80.

This body carries heat dissipative equipment, networks 90 of heat pipes suitable for transferring heat generated by the dissipative equipment to radiators 82, 84, networks 92 of heat pipes suitable for transferring heat to the -X face and heat transfer devices 2, 102 mounted between the networks 90, 92 of heat pipes to authorize or prohibit the transfer of heat from one network of heat pipes to another. Heat dissipative equipment is usually located inside the body. They are not shown in Figure 7.

The dissipative equipment 86 is illustrated diagrammatically in FIG. 8. They conventionally include active or passive radio frequency equipment, electronic components, measuring instruments, calculation units and batteries.

A third network of heat pipes (not shown) can also be mounted on the internal face of the radiator 82 and heat transfer devices can be mounted between the third network of heat pipes and the network of heat pipes 92.

FIG. 8 illustrates an example of use of two heat transfer devices 2, 102 according to the present invention mounted in redundancy between a first network of heat pipes 90 mounted on the face 80 and a second network of heat pipes 92 mounted on the face 74.

A thermal transfer device is called the nominal thermal transfer device 2. The other thermal transfer device is called the redundant thermal transfer device 102.

The first network 92 comprises a heat pipe called nominal heat pipe 94 and a heat pipe, called redundant heat pipe 96.

In this example, the nominal heat pipe 94 and the redundant heat pipe 96 are in direct thermal contact with the first main wall of the nominal heat transfer device 2 and with the first main wall 12 of the redundant heat transfer device 102. The second main wall 14 of the nominal thermal transfer device 2 and the second main wall 14 of the redundant thermal transfer device 102 are in direct thermal contact with the heat pipes of the second network of heat pipes 90.

This implementation of the present invention provides double redundancy since both when a heat pipe is pierced by a meteorite or when a heat transfer device is pierced by a meteorite, heat transmission is ensured by the other heat pipe or the other heat transfer device.

Claims (13)

1Thermal transfer device (2, 26, 30, 42, 48) capable of transferring heat between a first object (3) and a second object (4), comprising a housing (5, 50) having a first main wall ( 12, 52) and a second main wall (14, 54), the first main wall (12, 52) being intended to be in direct thermal contact by conduction with said first object (3), the second main wall (14, 54 ) being intended to be in direct thermal contact by conduction with said second object (4), said housing (5, 50) comprising an internal cavity (6) sealed, a liquid (8) contained in the internal cavity (6 ) and a mixer (10) suitable for setting said liquid in motion, the heat transfer device (2, 26, 30, 42, 48) being suitable for being switched between a first state in which the liquid (8) stagnates and a second state in which the liquid is in movement and transfers by forced convection of heat between the first main wall the (12, 52) and the second main wall (14, 54), the thermal conductance between the first main wall and the second main wall when the transfer device is in the first state being four times lower than the thermal conductance between the first main wall and the second main wall when the transfer device is in the second state. 2, - A heat transfer device (2, 26, 30, 42, 48) according to claim 1, which further comprises said first object (3) and wherein the first object is a heat pipe (28). 3, - A heat transfer device (2, 26, 30, 42, 48) according to any one of claims 1 and 2, which further comprises said second object (4) and wherein the second object is a heat pipe (28 ). 4, - A heat transfer device (2, 26, 30, 42) according to any one of claims 1 to 3, in which at least one wall from the first main wall (12) and the second main wall (14), has a flat outer face (17). 5. - A heat transfer device (2, 26, 30, 42) according to any one of claims 1 to 4, wherein the housing has the shape of a parallelepiped having a length (L), a width (I) and a height (h), the height (h) being the distance between the first main wall (12) and the second main wall (14), and in which the height (h) has a dimension twice less than said width ( I). 6. - A heat transfer device (2, 26, 30, 42) according to any one of claims 1 to 5, in which the fluid (8) is a dielectric fluid and in which the mixer (10) comprises at least two electrodes (20, 32) disposed at an interval (e) from each other and immersed in the dielectric fluid, the electrodes (20, 32) and the fluid (8) forming an electrohydrodynamic system (18). 7. - A heat transfer device (2, 26, 30, 42) according to claim 6, wherein said electrodes (20, 32) extend in a plane parallel to the median plane of the main walls (12, 14). 8. - A heat transfer device (2, 26, 30, 42, 48)) according to any one of claims 6 and 7, wherein the mixer (10) comprises a first support (36) adapted to carry at least two electrodes (20, 32) and a second support (38) suitable for carrying at least two electrodes (20, 32), the first (36) and the second (38) supports being arranged one next to the other in the same plane parallel to a main wall (12, 14), the at least two electrodes (20, 32) carried by the first support (36) being supplied by a first voltage (U1), the at least two electrodes carried by the second support (38) being supplied by a second voltage (U2), said second voltage (U2) being of opposite sign to the first voltage (U1), the circulation of the fluid between the electrodes (20, 32) of the first support (36) and the circulation of the fluid between the electrodes (20, 32) of the second support (38) being in opposite directions. 9. - A heat transfer device (2, 26, 30, 42, 48) according to any one of claims 1 to 8, in which the thermal conductance between the first main wall (12, 52) and the second main wall ( 14, 54) in the first state is less than 40 W / K / m ² and advantageously less than 8 W / k / m ² 10. - A thermal transfer device (2, 26, 30, 42, 48) according to any one of claims 1 to 9, in which the thermal conductivity between the first main wall (12, 52) and the second main wall ( 14, 54) in the second state is greater than 250 W / K / m ² and advantageously greater than 800 W / k / m ² . 11. A thermal transfer device (48) according to one of claims 1 to 5, in which the mixer is a mechanical device for driving the liquid (8). 12, - Space craft (62) comprising: - a body having a North face (78), a South face (80) opposite to the North face, an East face (72) and a West face (74) opposite to the East face; - at least one radiator (82, 84) carried by at least one face from the North face (78) the South face (80), the East face (72) or the West face (74), - at least one dissipative device 86) connected by a nominal heat transfer device (2) to at least one radiator (82,84); characterized in that the nominal thermal transfer device (2) comprises at least one thermal transfer device (2, 26, 30, 42, 48) according to any one of claims 1 to 11, so as to allow thermal conductance switchable between the dissipative equipment (86) and the radiator (82, 84) according to the state of the heat transfer device (2, 26, 30, 42, 48). 13.- spacecraft (62) according to claim 12, which comprises at least one redundant heat transfer device (102), a nominal heat pipe (94) and a redundant heat pipe (96), and in which a main wall (12, 14) of the main transfer device (2) and a main wall (12, 14) of the redundant transfer device (102) is in thermal contact with said nominal heat pipe (94) and said redundant heat pipe (96). 1/4 2/4