Cooling device for electrical equipment, corresponding system, and aircraft comprising at least one such system

Abstract

ELECTRICAL EQUIPMENT COOLING DEVICE, CORRESPONDING SYSTEM AND AIRCRAFT COMPRISING AT LEAST ONE SUCH SYSTEM The invention relates to a device (1) for cooling electrical equipment (2), said device (1) comprising: - a circulation channel (11) containing a flow (110) of a two-phase cooling fluid (111); - a thermally conductive wall (13) intended to separate the channel (11) and the electrical equipment, - at least one fin (15) disposed within the channel (11) and extending from the wall (13), each fin (15) being configured to be in a position close to the wall when the temperature of the fin (15) is below a predetermined temperature, and to be in a position far from the wall when the temperature of the fin (15) is greater than or equal to the predetermined temperature.Such a device makes it possible to efficiently cool electrical equipment without having to reduce its power output in the event of very high heat losses. Fig. 2.

Description

Title of the invention: DEVICE FOR COOLING ELECTRICAL EQUIPMENT, CORRESPONDING SYSTEM AND AIRCRAFT COMPRISING AT LEAST ONE SUCH SYSTEM Technical field

[0001] The present invention relates to a cooling device for equipment electrical and / or electronic equipment (grouped under the terms “electrical equipment” in the remainder of the description). The invention relates more particularly to the cooling of such equipment by the circulation of a two-phase cooling fluid. The invention also relates to a cooling system comprising a cooling device and electrical equipment, as well as an aircraft comprising at least one such system. STATE OF THE PRIOR ART

[0002] In the context of aircraft electrification, we have seen energy requirements increase significantly in a few years. Indeed, the electrical systems linked to the flight of the aircraft (flight controls, calculators, flight computers, etc.) and the electrical systems dedicated to passengers (pressurization systems, ventilation systems, digital entertainment systems, etc.) generate an increase in the power to be delivered to ensure optimal operation of the aircraft in all conditions.

[0003] However, to meet these growing power needs, it is not always possible to increase the size of electrical equipment since constraints of size and weight, in particular, must be respected.

[0004] In an attempt to comply with the constraint relating to the size of this electrical equipment, one solution consists of increasing the operating temperature of the power electronics of this equipment, which however generates very significant thermal losses. To remedy this, the conventional single-phase liquid cooling system has been replaced by a two-phase cooling system 9 illustrated in Figs. 1a and 1b, also called a phase-change cooling system. Thus, the cooling fluid 93 circulating around or on the electrical equipment 92 will change phase, that is to say that the cooling fluid 93 will pass from the liquid state 93a to the gaseous state 93b upon contact with the wall 921 of the circuit of the electrical equipment 92.

[0005] A disadvantage of this solution lies in the fact that in the event of excessive heat flow 91 generated by the electrical equipment 92, in other words in the event of excessive heat flow (called critical heat flow - CHF), the wall 921 risks dry out, as illustrated in [Fig.lb]. If the wall 921 is dried out, that is to say if the wall 921 is no longer in contact with the fluid 93a in the liquid state, the temperature of the circuit of the electrical equipment 92 will only increase exponentially. The risks of degradation, or even destruction, of the electrical equipment 92 are therefore very high.

[0006] To counter this situation, it is known to reduce the power of the electrical equipment, at least temporarily, to lower the temperature of the circuit. However, this reduction in power may prove impossible, or even dangerous, for example during the takeoff phase of the aircraft or during specific maneuvers.

[0007] There is therefore a need to provide a solution for cooling electrical equipment, particularly for aircraft, which at least partially overcomes the aforementioned drawbacks. Preferably, this solution must be effective, simple to implement and compact. Statement of the invention

[0008] An object of the present invention is to propose a device for cooling electrical equipment which is simple to implement and which complies with the space constraints linked to aircraft in particular.

[0009] To this end, a device for cooling electrical equipment is proposed, said electrical equipment comprising a circuit whose temperature increases between a nominal operation of said electrical equipment in which the circuit delivers a nominal power and a critical operation in which the circuit delivers a critical power greater than the nominal power, said device (1) comprising:

[0010] - a circulation channel containing a flow of a cooling fluid, said fluid cooling being a two-phase fluid comprising a liquid phase and a gaseous phase,

[0011] - a thermally conductive wall intended to separate said channel and said circuit and intended to be in contact with said circuit,

[0012] - at least one fin arranged within said channel and extending from said wall, each fin comprising a proximal end secured to said wall and a distal end opposite the proximal end, each fin being movable between a close position, in which the distal end is close to said wall, and a distant position, in which the distal end is distant from said wall and at least partly obstructs said flow of cooling fluid.

[0013] Said at least one fin is configured to be in the close position when a temperature of the fin is lower than a predetermined temperature, and to be in the distant position when said temperature of the fin is greater than or equal to at said predetermined temperature.

[0014] The cooling device of the invention therefore makes it possible to effectively cool electrical equipment without having to reduce the power of the latter in the event of very high thermal losses.

[0015] Advantageously, said predetermined temperature is equal to the phase change temperature of said cooling fluid.

[0016] According to a particular aspect of the invention, said at least one fin comprises a first surface facing said wall when said at least one fin is in the close position, and a second surface opposite said first surface. In the distant position, said at least one fin is inclined relative to said wall and said flow of cooling fluid circulates towards said second surface of said at least one fin.

[0017] According to a particular aspect of the invention, said at least one fin comprises a first part made of metal and a second part made of shape memory alloy.

[0018] According to another particular aspect of the invention, said second part comprises a first portion secured to said wall and a second portion secured to said first portion at an elastically deformable junction, said second portion being movable relative to said wall between the close position and the distant position.

[0019] According to yet another particular aspect of the invention, said first part at least partly covers said second portion.

[0020] According to a particular aspect of the invention, said first metal part is selected from: copper, aluminum, gold, or inconel®, and said second part 157 in shape memory alloy is selected from: Nitinol (Nickel-Titanium alloy), Copper-Zinc-Aluminum alloy, Copper-Aluminum-Nickel alloy or Iron-Manganese-Silicon alloy.

[0021] According to a particular aspect of the invention, said second portion of the fin has a length configured so that, when said at least one fin is in the remote position, at least the distal end of said fin reaches the liquid phase when said wall is separated from said liquid phase by the gaseous phase of said cooling fluid.

[0022] According to a particular aspect of the invention, the device comprises a plurality of fins, said fins being arranged on said wall in line, in staggered rows, or a combination of these arrangements.

[0023] The invention also relates to a cooling system comprising electrical equipment and a device as described above, in which the wall of the device is in contact with the circuit of the electrical equipment.

[0024] The invention further relates to an aircraft comprising at least one cooling system- development as described above. Brief description of the drawings

[0025] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0026] [Fig. 1a] schematically illustrates a two-phase cooling system according to the prior art, when electrical equipment to be cooled is in nominal operation;

[0027] [Fig.lb] schematically illustrates the system of [Fig.la], when the electrical equipment to be cooled is operating at full power;

[0028] [Fig.2] schematically illustrates a cooling system according to the invention, when electrical equipment to be cooled is in nominal operation;

[0029] [Fig.3] schematically illustrates the system of [Fig.2], when the electrical equipment to be cooled is operating at full power;

[0030] [Fig.4] schematically and in isolation illustrates a cooling device according to the invention, when the electrical equipment to be cooled is operating at full power; and

[0031] [Fig.5] illustrates an aircraft comprising a plurality of cooling systems according to the invention.

[0032] DETAILED DESCRIPTION OF AN EMBODIMENT

[0033] Figs. 2 to 4 schematically illustrate a cooling device 1 according to the invention. This device 1 is intended to cool electrical equipment 2, and preferably electrical equipment 2 intended to be carried on board an aircraft A illustrated in [Fig.5].

[0034] The electrical equipment 2 comprises a circuit 20, for example a power electronics circuit, generating a heat flow 200 during its operation. Due to this heat flow 200, the temperature T1 of the circuit 20 is variable depending on the operation of the circuit 20. Thus, the temperature T1 of the circuit 20 increases when the power delivered by the circuit 20 increases. More precisely, the temperature T1 of the circuit 20 increases between a nominal operation of the electrical equipment 2 in which the circuit 20 delivers a nominal power PI and a critical operation in which the circuit 20 delivers a critical power P2 greater than the nominal power PL

[0035] For example, the nominal power PI encompasses a range of power values ​​corresponding to the nominal operation of the electrical equipment 2. The critical power P2 can be a power value from which the electrical equipment 2 is considered to be operating at full power.

[0036] When the critical power P2 is reached, the temperature T1 of the circuit 20 reaches a critical value. From this critical temperature, the heat flux 200 is called critical heat flux (CHF).

[0037] The cooling device 1 of the invention intended to cool such electrical equipment 2 comprises a circulation channel 11 containing a flow 110 of cooling fluid 111. According to the invention, the cooling fluid 111 circulating in the channel 11 is a two-phase fluid, that is to say that the cooling fluid 111 comprises two phases, namely a liquid phase 111a and a gaseous phase 111b, in the operating temperature range of the circuit 20.

[0038] The device 1 also comprises a wall 13 arranged between the channel 11 and the circuit 20 of the electrical equipment 2 and separating the channel 11 from the circuit 20. The wall 13 is thermally conductive and is in contact with the circuit 20 so as to promote heat exchanges from the circuit 20 to the flow 110, which makes it possible to cool the circuit 20. In a variant, it is possible for the wall 13 to be constituted by a wall of the electrical equipment 2.

[0039] For example, the wall 13 is made of copper, or aluminum, or gold, or inconel® (super alloy consisting mainly of nickel, chromium, iron, magnesium and titanium), or any other sufficiently thermally conductive metal, for example a metal with a thermal conductivity greater than 30 W / mK.

[0040] According to the invention, the device 1 comprises at least one elastic fin 15 arranged within the channel 11. In the example illustrated schematically in Figs. 2 to 4, a single fin 15 is shown and the remainder of this description is based on this example. It is easily understood that the device 1 could implement a plurality of fins 15 and that the following description of the fin 15 could apply to all of the fins 15 when the device 1 comprises a plurality of fins 15.

[0041] The fin 15 extends from the wall 13. More specifically, the fin 15 has a proximal end 151 secured to the wall 13 and a distal end 153 opposite the proximal end 151. The fin 15 is movable between a close position, in which the distal end 153 is close to the wall 13 (in other words, the fin 15 is lowered and extends generally parallel to the wall 13), and a distant position, in which the distal end 153 is distant from the wall 13 (in other words, the fin 15 is inclined relative to the wall 13). When the fin 15 is in the remote position, the fin 15 at least partially obstructs the flow 110 of cooling fluid 111 so as to create disturbances in the flow 110 and increase the heat exchanges between the circuit 20 and the cooling fluid 111.

[0042] More specifically, the fin 15 is configured to be in the close position when the temperature T3 of the fin 15 is lower than a predetermined temperature Tref and be in the raised position when the temperature T3 of the fin 15 is greater than or equal to the predetermined temperature Tref.

[0043] The close position of the fin 15 corresponds to a state in which the electrical equipment 2 is in nominal operation. Thus, the power PI delivered by the circuit 20 of the electrical equipment 2 is then considered to be nominal. The temperature T1 of the circuit 20 is therefore also included in the normal operating values. The heat exchanges between the circuit 20 and the cooling fluid 111 of the flow 110 are therefore sufficient to cool the wall 13. In this situation, the liquid phase 111a of the cooling fluid 111 therefore completely covers the wall 13. In other words, the gaseous phase 111b is not in contact with the wall 13 and the wall 13 is therefore completely wet. The cooling of the electrical equipment 2 is therefore effective.

[0044] When the circuit 20 delivers a higher power which reaches or exceeds the critical power P2, the temperature T1 of the circuit 20 increases. The increase in the temperature T1 of the circuit 20 will, consequently, increase the temperature T2 of the cooling fluid 111 and therefore the temperature T3 of the fin 15 until the temperature T3 of the fin 15 reaches and possibly exceeds the predetermined temperature Tref.

[0045] According to one embodiment, the predetermined temperature Tref corresponds substantially to the phase change temperature of the cooling fluid 111. Thus, when the predetermined temperature Tref is reached, the cooling fluid 111 will change phase so that the volume of the liquid phase 111a will decrease and the volume of the gaseous phase 11b will increase. In addition, due to the capillarity of the cooling fluid 111, the gaseous phase 111b will take the place of the liquid phase 111a and will at least partially cover the wall 13. The wall 13 will therefore dry out at the locations where the liquid phase 111a no longer covers the wall 13 and the temperature T1 of the circuit 20 will increase exponentially. In this situation, the wall 13 is therefore at least partially separated from the liquid phase 111a by the gaseous phase 111b.

[0046] In the state of the art, this situation is usually critical and requires reducing the power of the circuit 20 to allow the temperature T1 of the circuit 20 to drop and, consequently, the temperature T2 of the cooling fluid 111 to also drop so that the wall 13 is again covered by the liquid phase 11a. However, this need to reduce the power delivered by the circuit 20 is not satisfactory.

[0047] According to the invention, the fin 15 is configured to be in the remote position when the temperature T3 of the fin 15 reaches or exceeds the predetermined temperature Tref, that is to say when the temperature T3 of the fin 15 is greater than or equal to the predetermined temperature Tref. Since the predetermined temperature Tref is equal to the phase change temperature of the cooling fluid 111, the fin 15 passes from the close position to the far position globally during the phase change of the cooling fluid 111. Indeed, the temperature T3 of the fin 15 is globally identical to the temperature T2 of the cooling fluid 111 since the fin 15 is immersed in the cooling fluid 111 (that is to say the fin 15 is in direct contact with the cooling fluid 111).A relatively small difference, between five and ten degrees (depending on the cooling fluid used and the roughness of the fin 15), between the temperature T2 of the cooling fluid 111 and the temperature T3 of the fin 15 can however be observed during sudden changes in the temperature T1 of the circuit 20. When there are no or few variations in the temperature T1 of the circuit 20, the temperature T3 of the fin 15 tends to be equal to the temperature T2 of the cooling fluid 111.

[0048] In the position remote from the fin 15, it is considered that the electrical equipment 2 is in its critical operation, as described above. Thus, the temperature T2 of the cooling fluid 111 is therefore equal to or greater than the predetermined temperature Tref. Consequently, the liquid phase 11a of the cooling fluid 111 is at least partly no longer in contact with the wall 13, which therefore dries out. Depending on the temperature T2 of the cooling fluid 111, and therefore on the phase change of the cooling liquid 111, it may be that the wall 13 is completely dried out (i.e., completely covered by the gaseous phase 111b) or partially dried out (i.e., a part of the wall 13 is covered with the liquid phase 11a and another part is covered with the gaseous phase 111b).

[0049] The movement of the fin 15 from the position close to the position distant from the wall 13 makes it possible to create disturbances in the flow 110 of cooling fluid 111 which make it possible to increase the heat exchanges and therefore to ensure the heat transfer between the wall 13 and the cooling fluid 111. Thus, the circuit 20 can continue to operate at full power, without heating which could create an obstacle to the proper functioning of the electrical equipment 2.

[0050] In the illustrated embodiment, the fin 15 has a first surface 150a which faces the wall 13 when the fin 15 is in the close position. The fin 15 has a second surface 150b which is opposite the first surface 150a, and which is located on the side of the channel 11 when the fin 15 is in the close position. In the distant position, that is to say when the fin 15 is inclined with respect to the wall 13, or in other words when the fin 15 is straightened, the flow 110 of cooling fluid 111 circulates towards the second surface 150b of the fin 15. In this way, the fin 15 can create disturbances in the flow 110 when the temperature temperature T3 of the fin 15 is greater than or equal to the predetermined temperature Tref. When the temperature T3 of the fin 15 drops and falls below the predetermined temperature Tref, then the fin 15 must return to the close position. With this arrangement and this inclination of the fin 15, the flow 110 does not oppose the movement of the fin 15 towards the close position. On the contrary, the direction of the flow 110 (represented by the arrow 110 in Figs. 2 and 3) is favorable to the movement of the fin 15 from the distant position to the close position.

[0051] According to a particular aspect illustrated in [Fig. 4], the fin 15 is bimetallic and is made of at least one shape memory material. More precisely, the fin 15 comprises a first portion 155 made of metal and a second portion 157 made of shape memory alloy. The second portion 157 made of shape memory alloy allows elastic deformation of the fin 15. The deformation of the fin 15 is caused by the change in the temperature T3 of the fin 15.

[0052] More specifically, the second portion 157 is configured to deform the fin 15 and move the fin 15 from the close position to the distant position when the temperature T3 of the fin 15, which is substantially equal to the temperature T2 of the cooling fluid 111, reaches or exceeds the predetermined temperature Tref. As long as the temperature T3 of the fin 15 is greater than or equal to the predetermined temperature Tref, the shape memory alloy of the second portion 157 will maintain the fin 15 in the distant position. It is therefore the shape memory alloy of the second portion 157 which reacts to the change in temperature.Thus, when the temperature T3 of the fin 15 decreases and returns below the predetermined temperature Tref, the second part 157 will deform again to regain its initial shape while the first metal part 155 will assist the return to the close position of the fin 15, given that the first metal part 155 is operated in its elastic domain.

[0053] The second part 157 made of shape memory alloy goes through a so-called “learning” phase during which the fin learns to move from the close position to the distant position, and vice versa, at a desired temperature. The first part 155 made of metal makes it possible to assist the movement from the distant position to the close position.

[0054] Such a fin 15 elastically deformable as a function of the temperature T3 of the latter makes it possible to dispense with the use of a mechanism or an actuator to move the fin 15 between the close position and the distant position, and vice versa. The device 1 therefore has a reduced size which is optimized and particularly suitable for being implemented in an aircraft, for example.

[0055] Preferably, the second part 157 made of shape memory alloy comprises a first portion 157a integral with the wall 13 and a second portion 157b movable relative to the wall 13. The first portion 157a, which constitutes a base, is preferably fixed to the wall 13 in a manner ensuring good thermal conduction. For example, the fixing of the first portion 157a to the wall 13 is obtained by brazing, cold welding, laser welding or any other technique making it possible to obtain the same advantages. The type of fixing is notably selected as a function of the material of the wall 13 and the shape memory alloy constituting the second part 157 of the fin 15, the cooling fluid 111 used and the operating temperature T1 of the circuit 20.

[0056] The second portion 157 also comprises a junction 157c between the first 157a and the second 157b portions. This junction 157c constitutes the elastic deformation point of the fin 15 and allows the fin 15 to move between the close position and the distant position.

[0057] Preferably, the first metal part 155 at least partially covers the second portion 157b of the second part 157 of the fin 15. Preferably, the first part 155 covers a surface of the second portion 157b of the second part 157 of the fin 15, and more preferably, the second part 155 covers the second surface 150b of the fin 15. As previously, and depending on the material of the wall 13 and the shape memory alloy constituting the second part 157 of the fin 15, the cooling fluid 111 used and the operating temperature T1 of the circuit 20 in particular, the first part 155 is fixed to the second portion 157b of the second part 157 by gluing, cold welding, laser welding or any other technique making it possible to obtain the same advantages.Preferably, the attachment of the first portion 155 to the second portion 157b is carried out at each of the ends of the second portion 157b, that is to say near the junction 157c and at the distal end 153.

[0058] Preferably, the first metal part 155 is selected from: copper, or aluminum, or gold, or inconel®, or any other sufficiently thermally conductive metal, for example a metal with a thermal conductivity greater than 30 W / mK.

[0059] The second part 157 in shape memory alloy is selected from: Nitinol (Nickel-Titanium alloy), or Copper-Zinc-Aluminum alloy, or Copper-Aluminum-Nickel alloy, or Iron-Manganese-Silicon alloy.

[0060] Preferably, the second portion 157b of the fin 15 has a length Li (illustrated in [Fig.4]) configured so that, when the fin 15 is in the remote position, at least the distal end 153 of the fin 15 reaches the liquid phase 111b of the cooling fluid when the wall 13 is separated from the liquid phase 111a by the gas phase 111b. In other words, during critical operation of the electrical equipment 2 and therefore when the wall 13 is dried or partially dried (i.e. covered totally or partially by the gas phase 111b), the length Li of the second portion 157b of the fin 15 is sufficient to reach the liquid phase 111a. In this way, the fin 15 will create disturbances in the flow 110 of cooling fluid 111 which will promote heat exchanges. More particularly, the fact that the fin 15 can reach the liquid phase 111a when the wall 13 is separated from the liquid phase 111a by the gas phase 111b also makes it possible to create disturbances in the liquid phase 111a of the flow 110 to further improve heat exchanges. Thus, the temperature T2 of the cooling fluid 111 decreases more quickly. The same is therefore true for the temperature T1 of the circuit 20.

[0061] According to one embodiment, the second portion 157b of the fin 15 has a length less than the length necessary so that, when the fin 15 is in the remote position, at least the distal end 153 of the fin 15 reaches the liquid phase 111b of the cooling fluid when the wall 13 is separated from the liquid phase 111a by the gas phase 111b. In other words, the second portion 157b of the fin 15 does not reach the liquid phase 111b when the wall 13 is dried. The deployment of the fin 15 forces the recirculation of the fluid, which increases the heat exchanges, reducing the temperature of the fin 15 and the wall 13, and therefore rewetting of the wall 13 is possible. According to this configuration, the cooling efficiency is reduced and the rewetting time is extended compared to the configuration where the second portion 157b of the fin 15 has a sufficient length to reach the liquid phase 111b.

[0062] Preferably, the predetermined temperature Tref from which the fin 15 passes from the close position to the distant position, and vice versa, is equal to the phase change temperature of the cooling fluid 111. Because the temperature T3 of the fin is substantially equal to the temperature T2 of the cooling fluid 111, as soon as the cooling fluid 111 heats up too much and begins to change phase, then the fin 15 will straighten up to pass from the close position to the distant position. This change in position of the fin 15 makes it possible to promote heat exchanges and to prevent the temperature T2 of the cooling fluid 111 from increasing too much, the phase change from taking place and the wall 13 from drying out. This thus makes it possible to effectively cool the circuit 20, in particular preventing the wall 13 from drying out.Circuit 20 can thus continue to operate at full power without fear of overheating which could damage it.

[0063] In an embodiment not illustrated, it is conceivable that the device 1 implements a plurality of fins 15 in the channel 11 so as to create advantages of disturbances in the flow 110 and therefore to further improve the thermal exchanges between the cooling fluid 111 and the circuit 20.

[0064] The fins 15 may, for example, be arranged in a line and a column, or in a staggered pattern, on the wall 13. These arrangements make it possible to create disturbances that optimize the heat exchanges. With these arrangements, it is also possible to anticipate, that is to say to predict, the disturbances that will be created by the fins 15 and therefore the locations where the heat exchanges will take place. It is therefore also possible to arrange the fins 15 at specific locations in the channel 11 corresponding to points in the circuit 20 releasing the most heat. The fins 15 may thus be placed in the areas of the channel 11 where hot spots have been identified. The density of the fins 15 may be greater, for example twice as high, in these areas of the channel 11 where hot spots have been identified than in other areas of the channel 11 where no hot spots have been identified.Other arrangements can obviously be envisaged without departing from the principle of the invention.

[0065] Figs. 2 and 3 represent a cooling system 10 according to the invention comprising a device 1 as described previously and electrical equipment 2 to be cooled. To allow the cooling of the electrical equipment 2, the wall 13 of the device 1 is then brought into contact with the electrical equipment 2, and preferably with the circuit 20 which generates the thermal flow 200, to allow thermal exchanges between the flow 110 of cooling fluid 111 and the thermal flow generated by the circuit 20.

[0066] [Fig. 5] represents an aircraft A comprising at least one cooling system 10 as described above. In this example, several systems 10 are implemented in the aircraft A. The use of such systems 10 in an aircraft advantageously makes it possible to use the electrical equipment 2 in operation at full power for desired durations, without having to reduce the power due to untimely heating of the electrical equipment 2. In this way, the use of the electrical equipment 2 is optimized and corresponds in particular to the operating and space constraints encountered in an aircraft.

Claims

Claims

1. Device (1) for cooling electrical equipment (2), said electrical equipment (2) comprising a circuit (20) whose temperature (Tl) increases between a nominal operation of said electrical equipment (2) in which the circuit (20) delivers a nominal power (PI) and a critical operation in which the circuit (20) delivers a critical power (P2) greater than the nominal power (PI), said device (1) comprising: - a circulation channel (11) containing a flow (110) of a cooling fluid (111), said cooling fluid (111) being a two-phase fluid comprising a liquid phase (111a) and a gaseous phase (Hlb), - a thermally conductive wall (13) intended to separate said channel (11) and said circuit (20) and intended to be in contact with said circuit (20), - at least one fin (15) arranged within said channel (11) and extending from said wall (13),each fin (15) comprising a proximal end (151) secured to said wall (13) and a distal end (153) opposite the proximal end (151), each fin (15) being movable between a close position, in which the distal end (153) is close to said wall (13), and a distant position, in which the distal end (153) is distant from said wall (13) and at least partly obstructs said flow (110) of cooling fluid (111); wherein said at least one fin (15) is configured to be in the close position when a temperature (T3) of the fin (15) is lower than a predetermined temperature (Tref), and to be in the distant position when said temperature (T3) of the fin (15) is greater than or equal to said predetermined temperature (Tref).,

2. Cooling device (1) according to claim 1, characterized in that said predetermined temperature (Tref) is equal to the phase change temperature of said cooling fluid (111).

3. Cooling device (1) according to claim 1 or 2, characterized in that said at least one fin (15) comprises a first surface (150a) facing said wall (13) when said at least one fin (15) is in the close position, and a second surface (150b) opposite said first surface (150a), wherein, in the remote position, said at least one fin (15) is inclined relative to said wall (13) and wherein said flow (110) of cooling fluid (111) flows towards said second surface (150b) of said at least one fin (15).

4. Cooling device (1) according to any one of claims 1 to 3, characterized in that said at least one fin (15) comprises a first part (155) made of metal and a second part (157) made of shape memory alloy.

5. Cooling device (1) according to claim 4, characterized in that said second part (157) comprises a first portion (157a) integral with said wall (13) and a second portion (157) integral with said first portion (157a) at an elastically deformable junction (157c), said second portion (157b) being movable relative to said wall (13) between the close position and the distant position.

6. Cooling device (1) according to claim 5, characterized in that said first part (155) at least partly covers said second portion (157b).

7. Cooling device (1) according to any one of claims 4 to 6, characterized in that said first part (155) made of metal is selected from: copper, or aluminum, or gold, or inconel®, and in that said second part (157) made of shape memory alloy is selected from: Nitinol, or the Copper-Zinc-Aluminum alloy, or the Copper-Aluminum-Nickel alloy, or the Iron-Manganese-Silicon alloy.

8. Cooling device (1) according to any one of claims 5 to 7, characterized in that said second portion (157b) has a length (Li) configured so that, when said at least one fin (15) is in the remote position, at least the distal end (153) of said fin (15) reaches the liquid phase (111b) when said wall (13) is separated from said liquid phase (11a) by the gaseous phase (111b) of said cooling fluid (111).

9. Cooling device (1) according to any one of claims 1 to 8, characterized in that it comprises a plurality of fins (15), said fins (15) being arranged on said wall (13) in line, in staggered rows, or a combination of these arrangements.

10. Cooling system (10) comprising electrical equipment (2) and a cooling device (1) according to any one of the re- claims 1 to 9, wherein said wall (20) of said device (1) is in contact with said circuit (20) of said electrical equipment (2).

11. Aircraft (A) comprising at least one cooling system (10) according to claim 10.

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