Fluid circulation device, installation and method using such a device

Abstract

The invention relates to a fluid circulation device comprising a casing (2) containing an electric machine (3), a cycle-gas circuit (5) subjecting the cycle gas to a change between a minimum pressure and a maximum pressure, a cycle-gas drive member (4) rotationally coupled to the electric machine (3), an electrical junction box (6) through which there passes electric circuitry (8) having one end connected to the electric machine (3) and one end connected to an electrical coupling (7) open to the outside, the device (1) comprising a cycle-gas conveying pipe (15) connected to a portion of the circuit (5) in which the cycle gas is at a pressure higher than the minimum pressure and to the inside of the junction box (6), the junction box (6) comprising a passage (9) for communicating with the inside of the casing (2), the conveying pipe (15), the passage (9) and the return pipe (25) being configured to bleed a fraction of the cycle gas from the circuit (5) and pass it through the junction box (6) with a view to cooling same before returning to the circuit (5).

Description

Fluid circulation device, installation and method using such a device.

[0001] The invention relates to a fluid circulation device as well as to an installation and a method using such a device.

[0002] The invention relates more particularly to a fluid circulation device, in particular for a refrigerator or cryogenic liquefier, comprising a casing sealed with respect to the exterior of the device and containing an electrical machine such as an electric motor or an alternator, the device comprising a cycle gas circuit subjecting the cycle gas to a thermodynamic change between a minimum pressure and a maximum pressure when the device is in operation, the device comprising at least one member for driving the cycle gas in the circuit such as a compressor wheel, said drive member being coupled in rotation to the electrical machine,the device comprising an electrical junction box sealed with respect to the exterior of the device and in which passes an electrical circuit having a first end connected to the electrical machine and a second end connected to at least one electrical connection opening outside the junction box and located outside the casing.,

[0003] The invention relates in particular to a system for cooling an electrical junction box of an electric motor by a flow of cycle gas.

[0004] It may indeed be necessary to cool the electrical supply enclosure (junction box) of an electric motor or turbomachine.

[0005] This junction box is often located far from the gas circulation or cooling water radiator of the central part of the associated engine or turbomachine.

[0006] In known solutions, this box is cooled by natural convection, by conduction through the walls of the junction box. In addition, heat management is ensured by sizing the junction box and increasing its surface area with the ambient temperature, the diameter of the cables and the size of the spark plugs or electrical connections. These measures increase the overall size of the junction box, its weight, its manufacturing cost, and the risk of leakage.

[0007] Additionally, due to its ability to withstand pressure, the wall thickness of such a case limits its conduction cooling.

[0008] An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

[0009] To this end, the device according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the device comprises a pressurized cycle gas supply pipe comprising a first end connected to a portion of the circuit in which the cycle gas is at a pressure higher than the minimum pressure and a second end communicating with the inside of the junction box, the junction box comprising a passage for communication with the inside of the casing, the fluid circuit comprising a cycle gas return pipe comprising a first end communicating with the inside of the casing and a second end connected to the circuit, the supply pipe,the passage and return line being configured to take a fraction of the cycle gas flowing in the circuit to circulate it in the junction box in order to cool the latter before returning to the circuit.,

[0010] Furthermore, embodiments of the invention may comprise one or more of the following features: the first end of the supply pipe is connected to the circuit downstream of an outlet of a drive member, the second end of the supply pipe opens into the casing and / or into the junction box, the first end of the return pipe opens into the casing and / or into the junction box, the second end of the return pipe is connected to the circuit upstream of an inlet of a drive member, the device comprises a member for regulating the flow rate of the fluid circulating in the supply pipe, the flow rate regulating member comprises at least one of: a valve, a calibrated orifice, the fluid circuit comprises a member for cooling the flow of fluid such as a heat exchanger arranged between an outlet of the circulation member and the first end of the bypass pipe,the passage and a first end of the return pipe are located at opposite ends of the junction box, the electrical circuitry which passes through the junction box comprises a set of electrical cable(s), the passage comprising a communication orifice between the interior of the junction box and the interior of the casing and through which the set of cable(s) extends, the device comprises at least two separate casings each containing an electrical machine for driving respective drive members, each electrical machine being provided with a respective electrical junction box communicating with the casing via a passage,the device comprising at least two pressurized cycle gas supply lines each comprising a first end connected to a portion of the circuit in which the cycle gas is at a pressure higher than the minimum pressure and a second end communicating with the interior of a corresponding junction box, the first end of a first supply line to the casing of a first electrical machine is connected to the fluid circuit downstream of the outlet of a first drive member, the device comprising a transfer line having a first end connected to the casing of the first electrical machine and a second end opening into the junction box of the second electrical machine, the device comprising a return line comprising a first end communicating with the second casing and a second end connected to the circuit, the first supply line, the transfer line,the passages and the return pipe being configured to take a fraction of the fluid flow flowing in the fluid circuit to circulate it in series in the junction boxes in order to cool the latter before returning to the circuit, the device comprises two supply pipes having first ends connected to the circuit and second ends communicating in parallel respectively with the two junction boxes and / or with the two casings, the first ends of the two supply pipes are connected to the same portion of the circuit.,

[0011] The invention also relates to a refrigeration and / or liquefaction installation comprising a refrigerator comprising a working circuit for a cycle gas, said circuit comprising, arranged in series, at least one cycle gas compression stage, at least one cycle gas cooling member, at least one cycle gas expansion stage and at least one cycle gas reheating member, the installation comprising a circulation device according to any one of the characteristics above or below in which the drive member comprises a compressor wheel forming a compression stage.

[0012] According to other possible features: the at least one cycle gas heating member comprises a heat exchanger in heat exchange with an element to be cooled, for example a fluid flow, the cycle gas comprises at least one of: nitrogen, helium, hydrogen, argon, neon.

[0013] The invention also relates to a method for cooling an electrical junction box of an electric motor of a circulation device conforming to any one of the characteristics above or below or of a aforementioned installation, the method comprising a step of sampling a fraction of the fluid flow flowing in the fluid circuit and circulating this fraction of fluid in the junction box in order to cool the latter, then a step of returning this fraction of fluid to the fluid circuit.

[0014] According to other possible particularities:

[0015] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims.

[0016] Other features and advantages will appear on reading the description below, made with reference to the figures in which:

[0017] represents a schematic and partial view illustrating a first example of structure and possible operation of a device according to the invention,

[0018] represents a schematic and partial view illustrating a first example of structure and possible operation of an installation according to the invention,

[0019] represents a schematic and partial view illustrating a second example of structure and possible operation of an installation according to the invention,

[0020] represents a schematic and partial sectional view illustrating a first possible example of a detail of the junction box of the device or installation according to the invention,

[0021] represents a schematic and partial view illustrating a second example of structure and possible operation of a device according to the invention,

[0022] represents a schematic and partial sectional view illustrating a second possible example of a detail of the junction box of the device or installation according to the invention,

[0023] represents a schematic and partial sectional view illustrating a third possible example of a detail of the junction box of the device or installation according to the invention,

[0024] represents a schematic and partial view illustrating a third example of structure and possible operation of an installation according to the invention.

[0025] The fluid circulation device 1 illustrated as an example at is preferably intended to be used in a cryogenic refrigerator or liquefier using a cycle gas. Of course, it could be used in other devices such as a compression device for example (in particular a non-cryogenic compressor).

[0026] The device 1 comprises a casing 2 sealed with respect to the exterior of the device and containing an electric motor 3, at least one fluid drive member 4 such as a compressor wheel mounted on a shaft 20 driven in rotation by the electric motor 3 to form a cycle gas compression stage. The device 1 comprises a cycle gas circuit 5 and comprising a downstream portion connected to an outlet of the drive member 4 (outlet of the compression stage for example).

[0027] The device 1 comprises an electrical junction box 6 sealed with respect to the exterior of the device and in which an electrical circuit 8 passes. The junction box 6 is for example mounted on or secured to the casing 2. For example, the junction box 6 is a box separate from the casing 2 and communicating with the casing 2 via one or more passage(s) or orifice(s). Similarly, at least a portion of the walls delimiting the junction box 8 may be common and merged with a portion of at least one wall delimiting the casing 2.

[0028] The electrical circuitry 8 has a first end connected to the motor 3 (via a passage 9 through the housing 6 and casing 2 or other) and a second end connected to at least one electrical connection 7 opening outside the junction box 6. The electrical connection 7 is typically located outside the casing 2 (and the device 1 if applicable).

[0029] As illustrated, the electrical circuitry 8 which passes through the junction box 6 may comprise a set of electrical cable(s). These cables may be connected to at least one connector 7, for example of the male type, which is mounted and projects for example on a wall or cover which seals the box 6 (for example via a screw or stud fixing assembly and a sealing system cf.). For example, the connector(s) 7 are surrounded by a protective wall. The connector 7 thus forms an electrical junction which is external to the device 1 and in particular at ambient temperature while the interior of the junction box 6 contains an atmosphere protected from the outside, for example a gaseous volume with a determined composition and pressure.

[0030] The circuit 5 comprises a supply pipe 15 comprising a first end connected to a portion of the circuit 5 in which the working gas is not at its minimum pressure in the circuit 5 (typically downstream of a compression stage) and a second end opening into the junction box 6.

[0031] The junction box 6 further comprises at least one passage 9 for communication with the interior of the casing 2 of the motor. If necessary, all or part of the electrical circuitry (cables, etc.) can pass via this passage 9 as shown diagrammatically in.

[0032] The circuit 5 comprises a return pipe 25 comprising a first end communicating with the interior of the casing 2 and a second end connected to the circuit 5, in a portion of the circuit in which the working gas is not at its maximum pressure, in particular at a pressure equal to or greater than the minimum pressure, for example upstream of the compression member 4. The supply pipe 15, the passage 9 and the return pipe 25 are thus configured to take a fraction of the flow of pressurized working gas flowing in the circuit 5 to circulate it in the junction box 6 in order to cool the latter before returning to the circuit 5.

[0033] This makes it possible to cool the electrical supply enclosure (junction box 6) of an engine 3 or a turbomachine, for example, using a flow of pressurized cycle gas circulated in the hermetic (or semi-hermetic) part of a junction box 6. This fluid flow can be enabled by the supply and extraction of gas (or liquid) through pipes, machined cavities and / or cable passages, for example.

[0034] In particular, as illustrated in the, the passage 9 may comprise a communication orifice between the interior of the junction box 6 and the interior of the casing 2 and through which the set of cable(s) passes.

[0035] Preferably, the passage 9 and the first end of the return pipe 25 which opens into the junction box 6 are located at opposite ends of the junction box 6 to thus promote efficient mixing and cooling by the flow of cycle fluid.

[0036] The drive of this coolant flow can be achieved by a dynamic pressure drop between the injection and discharge point of the engine or the pipes connecting to it.

[0037] As illustrated, preferably, the circuit 5 may comprise a member 11 for regulating the flow rate of the fluid circulating in the bypass pipe 15, for example a valve, a calibrated orifice or any other suitable member (piloted valve for example). The flow rate regulating member 11 may be arranged on the supply pipe 15.

[0038] As illustrated, the circuit 5 may advantageously comprise a member 12 for cooling the fluid flow such as a heat exchanger preferably arranged between the circulation member 4 (compression stage) and the first end of the supply pipe 15. This cooling member 12 may be a cooling heat exchanger conventionally arranged at the outlet of a compression stage to cool the compressed cycle gas flow (by heat exchange with a heat transfer medium, such as water or other fluid for example).

[0039] The fluid circulation device 1 illustrated as an example in is a motor-turbo compressor comprising a compression wheel and a turbine 16 mounted on the shaft 20 of the engine 3. Of course, this is only a non-limiting example because the invention could be applied to a simple motor-compressor (engine driving one or more compression wheels) or any other arrangement (one or more compression wheels and one or more turbines).

[0040] Describes an example of implementation in a refrigerator or liquefier producing cold power by subjecting a cycle gas to a thermodynamic cycle in a working circuit.

[0041] The working circuit 5 may comprise, arranged in series, at least one stage 4 for compressing the cycle gas, at least one member 12, 14 for cooling the cycle gas (heat exchanger(s) for example), at least one stage 16 for expanding the cycle gas (turbine(s) or valve(s) for example) and at least one member 17, 14 for reheating the cycle gas (heat exchanger(s) for example). The compression member 4 (at least one stage) may comprise a circulation device 1 of the aforementioned type.

[0042] A heat exchanger 12 for cooling the cycle gas at the outlet of the compression stage can ensure the cooling of the cycle gas which will be used to cool the junction box 6.

[0043] The cooling and reheating of the cycle gas can be ensured by at least one counter-current heat exchanger 14 receiving a flow of cycle gas at distinct temperatures in the cycle. At its coldest end in the cycle, the cycle gas can be reheated by releasing its frigories by heat exchange with a member to be cooled in a heat exchanger 17 (flow 13 of fluid to be cooled or liquefied for example).

[0044] The invention can be applied to a device (refrigerator or other) comprising several motors 3 each having an electrical junction box 6. All or part of the motors can comprise a respective cooling system of the type described above. Alternatively or in combination, motors can share or pool all or part of the cooling system described above.

[0045] In the non-limiting example of the, the refrigeration / liquefaction installation 10 comprises two motors 3 and the two corresponding junction boxes 6 are cooled by the same cycle gas flow. The device comprises in this example an expansion stage (a turbine 16).

[0046] More precisely, each motor 3 is provided with a respective electrical junction box 6 communicating with the corresponding casing 2 via a passage 9. The supply pipe 15 comprises a first end connected to the circuit 5, for example at a portion downstream of the drive member 4 of a first motor 3 (for example at the outlet of the second cycle gas compression stage).

[0047] The device 1 comprises a transfer pipe 35 having a first end connected to the casing 2 of the first engine 3 and a second end opening into the junction box 6 of the second engine 3 (of the first compression stage upstream in the working circuit of the cycle gas). As illustrated, the transfer pipe 35 preferably comprises a member 13 for cooling the cycle fluid flow such as a heat exchanger cooled by a heat transfer medium (water, air or other) to cool the cycle gas before cooling the second junction box 6.

[0048] The return pipe 25 comprises a first end communicating with the interior of the casing 2 of the second engine 3 and a second end connected to a portion of the fluid circuit 5, for example upstream of the first compression stage. As shown schematically in dotted lines, the return pipe 25 may optionally comprise a member 25 for cooling the cycle gas flow (heat exchanger or other) before its reinjection upstream of a compression stage.

[0049] Thus, the supply line 15, the transfer line 35, the passages 9 and the return line 25 make it possible to take a fraction of the compressed cycle gas to circulate it in series in the junction boxes 6 in order to cool the latter before returning to the circuit 5.

[0050] The example of the has two series compression stages of cycle gas having a cooling exchanger 12 at the outlet of each compression stage. Similarly, the illustrated device has a single expansion stage (a turbine 16).

[0051] Of course, the invention can be applied to any other type of installation architecture and in particular any type of refrigerator or cryogenic liquefier (typically bringing a working gas to a temperature below -150°C) with one or more compression stages and expansion stages with a different number of motors.

[0052] The variant of la differs from that of la only in that the first end of the supply line 15 is connected between the two compressors 4 in series, for example downstream of the cooling exchanger 12.

[0053] Furthermore, the invention can be applied to a device 1 in which the motor 3 (or at least one of the motors) is replaced by any other electrical machine, for example an alternator. In this case, the drive member 4 can comprise a turbine. The turbine(s) 16 can be provided for the recovery of mechanical work intended to produce electrical power.

[0054] Likewise, the first end of the supply pipe can be connected downstream of another member of the circuit 5, in particular downstream of a member 4 different from that driven or coupled to the electric machine 3 whose junction box 6 must be cooled.

[0055] Typically, the first end of the supply line(s) 15 is preferably connected to a point in the circuit where the pressure of the cycle gas is higher than the lowest pressure of the cycle gas in the circuit 5. In fact, the cycle gas is subjected in the circuit 5 to a thermodynamic transformation (in particular a compression / expansion cycle) between at least two states at low (minimum) and high (maximum) pressures. The cycle gas which is taken from the circuit 5 to cool at least one junction box 6 is preferably at a pressure higher than its minimum pressure in the circuit 5.

[0056] For example, this cycle gas is taken from circuit 5 downstream of at least one of the compressors 4 of circuit 5.

[0057] For example, this cycle gas is taken downstream of the compressor 4 coupled in rotation to the shaft of the motor 3 whose junction box 6 must be cooled. However, this first end of the supply pipe 15 can be connected to the outlet of another compressor 4 (or other member 4) coupled to another motor 3 or electrical machine of the device 1.

[0058] Likewise, the second end of the return line 25 is preferably connected to a portion of the circuit in which the pressure of the cycle gas is relatively low (less than the maximum pressure), for example to the inlet of one of the compressors 4. For example, the return line 25 is connected to the inlet of the compressor 4 coupled (driven) by the engine 4 whose junction box 6 is cooled by the cycle gas.

[0059] In the variant illustrated in the, the device comprises two motors 3 each driving a compressor 4. One of the motors 3 is also coupled to a turbine 16 via the same shaft driving the compressor.

[0060] Conventionally, each motor 3 can comprise a stator 32 and a rotor 31 coupled to a rotating shaft carrying the wheels (compressor(s) 4 and turbine(s) 16).

[0061] In this example, two supply lines 15 have a first end (common in this example) connected downstream of a first 4 of the two compressors 4 in series, for example downstream of an exchanger 12 for cooling the compressed cycle gas. The second ends of the two supply lines 15 are connected in parallel respectively to the two casings 2. The pressurized cycle gas then passes into the junction boxes 6 via the passages 9 and leaves the box 6 and the casing 2 via return lines 25. The two return lines 25 can be connected again to the inlet of the same compressor 4, for example to the first 4 of the two compressors in series. Thus, the pressurized cycle gas used for cooling the junction box 6 can first pass through the corresponding casing 2 before passing through the junction box 6.

[0062] As illustrated, the device 1 may further comprise a conduit 21 diverting a portion of this pressurized cycle gas to a labyrinth system 18 at the level of bearings of the shaft of the engine 3. Typically this labyrinth system 18 is provided to separate the gaseous atmosphere in the casing 2 from the outside. That is to say, a conduit 21 may be connected in parallel to the supply conduit 15 to a labyrinth (or any bearing system). This conduit 21 (just like the supply conduit 15) preferably comprises a valve system 22 allowing opening or closing independently as required.

[0063] It illustrates that the second end of the supply pipe 15 can open into the casing 2 and into the junction box 6. A majority flow (for example of the order of 90% of the flow) supplies the casing 2 for its cooling), the remainder of the flow supplies the interior of the junction box 6. The cycle gas flow which cools the junction box 6 joins the casing 2 via a portion of the return pipe 25 which can contain the electrical cables (forming the passage 9). The cooling cycle gas flows are symbolized by curved arrows.

[0064] In the embodiment of the, the second end of the supply pipe 15 opens into the casing 2, the flow of cycle gas then passes into the junction box 6 via at least one passage 9 and then leaves again in the volume 2 of the casing 2. Thus, the injected cycle gas first passes into the engine casing 2 and then reaches the junction box 6, passing for example at the same location as the electric cables.

[0065] Thus, the pressurized cycle gas can be taken by the first end of at least one supply pipe 15 at any suitable location in the circuit 5 to be brought into a junction box 6 directly or via a casing 2 or other.

[0066] The invention makes it possible to provide compact junction boxes 6 while ensuring efficient cooling of the latter.

[0067] In applications using frequencies equal to or greater than 100Hz, electric currents flow preferentially on the surface of conductive materials. The device is particularly suitable for cooling elements with such skin effects by reducing the surface temperature.

[0068] In the example shown, a single electrical connection 7 is shown, but the invention could be applied to junction boxes 6 comprising several connections or plugs depending on the number of phases of the electric motor and connections or plugs necessary to power the electric motor.

[0069] The efficiency of the cooling also allows a reduction in the cross-section of the cables and other electrical components in the junction box 6.

[0070] The invention thus allows an improvement in the thermal behavior and pressure resistance of the electrical junction to a motor.

Claims

Fluid circulation device, particularly for a refrigerator or cryogenic liquefier, comprising a housing (2) sealed against the outside of the device (1) and containing an electrical machine (3) such as an electric motor or an alternator, the device (1) comprising a cycle gas circuit (5) subjecting the cycle gas to a thermodynamic change between a minimum pressure and a maximum pressure when the device is in operation, the device comprising at least one cycle gas drive element (4) in the circuit (3) such as a compressor wheel, said drive element (4) being rotationally coupled to the electrical machine (3),the device (1) comprising an electrical junction box (6) sealed with respect to the outside of the device and through which passes an electrical circuit (8) having a first end connected to the electrical machine (3) and a second end connected to at least one electrical fitting (7) opening outside the junction box (6) and located outside the housing (2), characterized in that the device (1) comprises a pressurized cycle gas supply line (15) comprising a first end connected to a portion of the circuit (5) in which the cycle gas is at a pressure greater than the minimum pressure and a second end communicating with the inside of the junction box (6), the junction box (6) comprising a passage (9) for communication with the inside of the housing (2),the fluid circuit (5) comprising a cycle gas return line (25) having a first end communicating with the interior of the casing (2) and a second end connected to the circuit (5), the supply line (15), the passage (9) and the return line (25) being configured to take a fraction of the cycle gas flowing in the circuit (5) to circulate it through the junction box (6) in order to cool the latter before returning to the circuit (5). Device according to claim 1, characterized in that the first end of the supply pipe (15) is connected to the circuit (5) downstream of an output of a drive element (4). Device according to claim 1 or 2, characterized in that the second end of the supply conduit (15) opens into the housing (2) and / or into the junction box (6). Device according to any one of claims 1 to 3, characterized in that the first end of the return pipe (25) opens into the housing (2) and / or into the junction box (6). Device according to any one of claims 1 to 4, characterized in that the second end of the return line (25) is connected to the circuit (5) upstream of an input of a drive element (4). Device according to any one of claims 1 to 5, characterized in that it comprises a flow control element (11) for the fluid circulating in the supply line (15). Device according to claim 6, characterized in that the flow control member (11) comprises at least one of: a valve, a calibrated orifice. Device according to any one of claims 1 to 7, characterized in that the fluid circuit (5) comprises a fluid flow cooling element (12) such as a heat exchanger disposed between an outlet of the circulation element (4) and the first end of the bypass pipe (15). Device according to any one of claims 1 to 8, characterized in that the passage (9) and a first end of the return conduit (25) are located at opposite ends of the junction housing (6). Device according to any one of claims 1 to 9, characterized in that the electrical circuitry (8) which passes through the junction box (6) comprises a set of electrical cable(s) and in that the passage (9) comprises a communication orifice between the inside of the junction box (6) and the inside of the housing (2) and through which the set of cable(s) extends. Device according to any one of claims 1 to 10 comprising at least two separate housings (2) each containing an electric machine (3) for driving respective drive elements (4), each electric machine (3) being provided with a respective electrical junction box (6) communicating with the housing (2) via a passage (9), the device comprising at least two pressurized cycle gas supply lines (15) each comprising a first end connected to a portion of the circuit (5) in which the cycle gas is at a pressure greater than the minimum pressure and a second end communicating with the interior of a corresponding junction box (6). Device according to claim 11, characterized in that the first end of a first supply line (15) to the housing of a first electrical machine (3) is connected to the fluid circuit (5) downstream of the outlet of a first drive element (4), the device comprising a transfer line (35) having a first end connected to the housing (2) of the first electrical machine (3) and a second end opening into the junction box (6) of the second electrical machine (3), the device (1) comprising a return line (25) having a first end communicating with the second housing (2) and a second end connected to the circuit (5), the first supply line (15), the transfer line (35),the passages (9) and the return conduit (25) being configured to take a fraction of the fluid flow in the fluid circuit (5) and circulate it in series through the junction boxes (6) in order to cool them before returning to the circuit (5). Device according to claim 11, characterized in that it comprises two supply conduits (15) having first ends connected to the circuit (3) and second ends communicating in parallel respectively with the two junction boxes (6) and / or with the two housings (2). Device according to claim 13, characterized in that the first ends of the two supply pipes (15) are connected to the same portion of the circuit (3). Installation (10) for refrigeration and / or liquefaction comprising a refrigerator having a cycle gas working circuit (5), said circuit comprising, arranged in series, at least one cycle gas compression stage (4), at least one cycle gas cooling element (12, 14), at least one cycle gas expansion stage (16) and at least one cycle gas heating element (17, 14), characterized in that it comprises a circulation device (1) according to any one of claims 1 to 15 in which the drive element (4) comprises a compressor wheel forming a compression stage. Installation according to claim 15, characterized in that at least one cycle gas heating element comprises a heat exchanger (17) in heat exchange with an element (19) to be cooled, for example a fluid flow. Installation according to claim 15 or 16, characterized in that the cycle gas comprises at least one of: nitrogen, helium, hydrogen, argon, neon. Method of cooling an electrical junction box (6) of an electric motor (2) of a circulation device according to any one of claims 1 to 14 or of an installation according to any one of claims 15 to 17, characterized in that it comprises a step of taking a fraction of the fluid flow flowing in the fluid circuit (5) and circulating this fraction of fluid in the junction box (6) in order to cool the latter and then a step of returning this fraction of fluid to the fluid circuit (5).

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