DE102011079968B4 - Cooling device with wick-like material for transporting coolant - Google Patents

Abstract

Cooling device (1, 1 ', 1' '), comprising a condenser (4) coupled in particular to a cold head (5) for liquefying gaseous coolant, an evaporator (8) for evaporating liquid coolant (3) for cooling an object to be cooled ( 9) and a heat pipe (7) for transporting the coolant (3) between the evaporator (8) and the condenser (4), a wick-like material structure (11) being used to transport the liquid coolant (3) due to the capillary effect characterized in that a rotation device (13) is provided for rotating the material structure (11) about an axis of rotation lying in the transport direction of the liquid coolant (3) through the heat pipe (7), the material structure (11) on the evaporator side in the radial direction with respect to the Axis of rotation is fanned out.

Description

The invention relates to a cooling device, comprising a particularly coupled to a cold head condenser for liquefying gaseous coolant, an evaporator for evaporating liquid coolant for cooling an object to be cooled and a heat pipe for transporting the coolant between the evaporator and the condenser, wherein the transport of the liquid Coolant due to the capillary effect a wick-like material structure is used. In addition, the invention relates to a superconducting machine with such a cooling device.

In modern refrigeration systems, it is often desired to accomplish the delivery of refrigerant without spending a large amount of additional energy. In particular, the use of heat pipes is known in which an automatic transport, in particular of the liquid coolant to the evaporator can be realized due to different effects. One way of doing this, which is basically known in the art, is to use the capillary effect. This wicking materials are used, in which there are therefore cavities, can penetrate the liquid coolant due to the capillary effect in particular against gravity.

The use of the capillary effect proves to be problematic, especially in the case of cryogenic coolants, which have an extremely low surface tension, which makes it particularly difficult to bring about the escape of the coolant in the evaporator.

Such problems occur, for example, in superconducting machines, for example, in high-temperature superconductor machines usually liquid neon is used as a coolant. The coolant transport can be realized driven by gravity. However, applications are known, for example on ships, where it can not always be ensured that the coolant reservoir is arranged higher than the object to be cooled, in particular the rotor. If, for example, the rotor to be cooled of a high-temperature superconductor machine is higher than the existing liquid cryogenic coolant, then this must be conveyed uphill, which can not be implemented effectively effectively by means of a wick-like material. Thus, it has been proposed to use special low temperature suitable pumps for the promotion of cryogenic coolant uphill, but they are expensive and consume even a large amount of energy, so that the efficiency of the superconducting machine lowers.

DE 102 31 434 A1 relates to a device of the superconducting technique with thermally to a rotating superconducting winding coupled cold head of a refrigeration unit. The transport of the coolant from the fixed cold head to the rotatably mounted rotor is effected by a fixed heat pipe. The transport of the condensate through the heat pipe is done under the influence of gravity due to a so-called thermosiphon effect and optionally by the capillary force of the inner wall of the heat pipe. For this purpose, this tube acts in a conventional manner as a wick. This function can be optimized by appropriate design or lining of the inner wall.

DE 100 39 964 A1 relates to a superconducting device with a refrigeration unit for cooling a rotating, superconducting winding. Here, the superconducting device comprises a rotatably mounted rotor and a stationary cold head, which is rigidly and thermally conductively connected to a heat transfer cylinder, which projects into the cavity of the winding body while maintaining a hollow cylindrical annular gap. In one embodiment, a part of the heat transfer body is designed as a heat pipe according to the heat pipe or thermosyphon principle. If the heat pipe is designed according to the heat-pipe principle, a transport of the coolant can also take place counter to gravity.

DE 32 04 538 A1 relates to a heat pipe heat exchanger with rotating or axially moving pipes. Here is a uniform temperature distribution over the cross-sectional area of a rotating tube can be achieved. This is achieved by a screw in the condenser wall to improve the condensate return transport.

US 5 119 886 A concerns a "heat transfer cylinder". Again, a uniform heating of a rotating cylinder to be achieved. Individual heat pipes or a capillary structure on the inner surface of the cylinder serve for better return transport of the heating medium to the evaporator.

EP 1 437 821 A2 describes a "superconductor rotor cooling system". From this document is known a cooling device comprising a coupled to a cold head condenser for liquefying gaseous refrigerant, an evaporator for evaporating liquid refrigerant for cooling an object to be cooled and a heat pipe for transporting the refrigerant between the evaporator and the condenser. The transport of the coolant happens here first by gravity. In one embodiment, coolant transport is enhanced by utilizing the centrifugal force to move the coolant toward the warmer end of the cooling block. In In another embodiment, in which all the heat pipes are stationary, it should be noted that gravity, centrifugal force and wicks can be used to transport the liquid coolant to the coils.

The invention is therefore based on the object to provide a way to promote coolant, in particular cryogenic coolant and / or coolant with a low surface tension, using the capillary effect effectively and bring in an evaporator for evaporation.

To achieve this object, according to the invention, a rotation device for rotating the material structure is provided about an axis of rotation passing through the heat pipe in the transport direction of the liquid coolant, wherein the material structure fanned on the evaporator side in the radial direction with respect to the axis of rotation is. Thus, the present invention makes use first of all of the capillary effect, for example in a type of wick, in order to convey liquid coolant, in particular a cryogenic coolant, for example neon, also uphill. After the material structure rotates according to the invention during operation of the cooling device, in particular independent of the object to be cooled or together with this, the liquid coolant, in particular as droplets, detached from the material structure and radially outward into the evaporator, in particular to one by the acting centrifugal force Evaporating surface, on or in the object to be cooled, for example, in the hollow interior of a rotor of a superconducting machine, flung. The object to be cooled is cooled by the evaporating coolant, wherein the resulting gaseous coolant through the heat pipe back to the condenser, which is in particular connected to a cold head, where it can be liquefied again.

Thus, the capillary effect is used to convey cooling liquids, in particular in the case of cryogenic coolants, also against the force of gravity, whereby for the first time an effective decoupling at the end of the conveying path is made possible by the rotation by utilizing the centrifugal force.

Advantageously, therefore, no actively operated coolant pump is required, so that in this respect the cost, the cost and the risk of failure can be reduced. The entry of additional power loss is low or even absent, since it is conceivable to move the material structure together with the object to be cooled, for example an already rotating rotor of a superconducting machine. It is therefore a very simple, inexpensive construction of the cooling device allows. The liquid coolant can also be transported uphill against gravity and effectively decoupled at the end of the conveyor line.

It is particularly advantageous that the material structure is fanned on the evaporator side in the radial direction with respect to the axis of rotation. This means that at the end of the conveying path, the capillaries are fanned away from the axis of rotation, which significantly increases the centrifugal force at the end of the capillaries and thus significantly improves the detachment of the liquid coolant from the material structure. By means of a radial fanning of the capillaries and the increased centrifugal force acting at the end of the capillaries, the coolant is thus removed much better again and conveyed to an evaporating surface of the evaporator.

In a further embodiment of the present invention can be provided that the material structure outside of an evaporator-side outlet region and a condenser-side inlet region to the outside, in particular completely, is surrounded by a shell. In this way, in particular in the case of an open-pore structure on all sides, it is possible to prevent liquid coolant from being thrown off the material even before it has reached the evaporator, in particular due to the centrifugal force. On the other hand, it can also be provided that the shell acts as a socket of the material structure. For example, given a material structure in the manner of a thread or braided object, which is fanned on the evaporator side in the radial direction with respect to the axis of rotation can also be avoided by acting as a socket shell that unintentional further fanning or fraying occurs by the forces acting.

Furthermore, it can be provided that the sheath is formed as a tube. There are two possible configurations here. On the one hand, it can be provided that a wall of the heat pipe itself acts as a shell formed to the outside, if the wick-like material structure is applied, for example, to the inner wall of the heat pipe and / or is incorporated into the inner wall. It is also conceivable, however, with a freely guided structure, to surround the material structure with an additional tube, which in particular avoids the escape of liquid coolant outside the exit area and the entry area and / or stabilizes and encloses the material structure.

As already mentioned, it can be provided that the material structure is guided by a free space for the transport of gaseous coolant in the heat pipe. In this case, the material structure is therefore not in any way with an inner wall of the heat pipe or the like, but is guided freely, which can simplify the rotation.

Furthermore, it can be provided that the liquid coolant penetrates from a container for liquid coolant into the material structure. For example, then the condenser-side end of the conveying path, so the condenser-side inlet region, the material structure be completely stored within the liquid cooling medium, so that coolant can penetrate continuously into the capillaries of the material structure and can be transported. In this case, if the material structure is guided by a free space for transporting gaseous coolant in the heat pipe, it can be provided that the material structure is guided in a direction deviating from a center axis of the heat pipe. The material structure then passes "obliquely" through the heat pipe, as it were, in order to be able to dip on one side into a lower container for liquid coolant.

Alternatively, it can also be provided that the liquid coolant is applied to the material structure, in particular dripped. It is thus possible, for example, to feed the capillaries of the material structure directly, in particular droplets, from the condenser. This results in a fundamentally simpler design of the entire cooling device, after no complicated guidance of the rotating material structure must be provided in a container for liquid coolant.

In a further embodiment of the present invention can be provided that the material structure is rotatable with the object to be cooled. Such a configuration is conceivable, for example, in superconducting machines, in which a superconducting coil to be cooled is provided inside the already rotating rotor, so that, for example, the material structure can be guided into a hollow interior of the rotor and can rotate with it, so that the centrifugal force the liquid coolant is correspondingly distributed in the interior acting as an evaporator. In such a case can be dispensed with a separate drive for the material structure, so that a very simple, cost-effective design of the overall system is possible.

In addition to the cooling device, the invention also relates to a superconducting machine comprising at least one superconducting coil formed to produce a magnetic flux at poles of a rotor or stator and a cooling device according to the invention designed to cool the coil. All statements with regard to the cooling device can be analogously transferred to the superconducting machine, so that here too the mentioned advantages can be achieved. The conductors of the superconducting coil can consist in particular of a high-temperature superconductor. As a coolant can be used in this case neon, but it is also conceivable to work for example with hydrogen or helium or nitrogen.

It is possible in such superconducting machines, for example, to guide the rotating material structure through a coupled via a rotary feedthrough heat pipe into the hollow interior of a rotor, where the liquid coolant is distributed accordingly. It is also conceivable, for example, to allow the heat pipe and thus also the material structure to rotate with the rotor in order to set the material structure in rotation. It should be noted at this point, however, that it can be quite useful to use a separate rotation device, for example, if even when the superconducting machine is to be cooled.

Further advantages and details of the present invention will become apparent from the embodiments described below and with reference to the drawing. Showing:

1 a cooling device according to the invention in a first embodiment,

2 a cooling device according to the invention in a second embodiment,

three a cooling device according to the invention in a third embodiment, and

4 a superconducting machine according to the invention.

1 shows a first embodiment of a cooling device according to the invention 1 in a schematic diagram. This includes a container 2 for liquid coolant three , where neon is used as the coolant in the embodiment shown here. The container 2 is fed by a condenser 4 with an associated coldhead 5 , see. arrow 6 , The liquid coolant three should now have a heat pipe 7 in an evaporator 8th be spent, here an interior of an object to be cooled 9 on whose walls the liquid coolant three the cooling effect unfolding evaporates and according to the arrow 10 back to the condenser 4 to be led.

For transporting the liquid coolant three to the object to be cooled 9 is here a wick-like material structure 11 provided, which has capillaries, so that the liquid coolant three by the capillary effect against gravity in the direction of the evaporator 8th is transported. The material structure is obvious 11 fanned out there, with a shell acting as a frame 12 avoids further fanning of the thread-like material here.

Now to the liquid coolant three from the material structure 11 to the walls of the evaporator 8th to bring the material structure 11 by a rotation device 13 turned, cf. arrow 14 , The axis of rotation runs along the conveying direction of the material structure 11 ,

At the fanned ends 15 the material structure 11 After this is fanned out radially, a higher centrifugal force is created, which is sufficient for drops to form 16 of the liquid coolant three and to the walls of the object to be cooled 9 to be thrown, arrows 17 ,

2 shows a further, slightly modified embodiment of a cooling device according to the invention 1' in a schematic diagram. In contrast to the cooling device 1 is, for example, due to an open in all directions wick-like material of the material structure 11 , the case 12 ' tight for the liquid coolant three trained and encloses the material structure 11 except for an entry area 18 and an exit area 19 Completely. Here is the shell 12 ' here as a pipe 24 educated.

three shows a further modified third embodiment of a cooling device according to the invention 1'' in which the material structure 11 coaxial in the middle of the heat pipe 7 is guided. Also the rotation device 13 is arranged slightly modified here. Obviously, there is no container here 2 for liquid coolant three provided, but this is directly from the condenser 4 with the cold head 5 in the entrance area 18 dripped.

4 finally shows a schematic diagram of a superconducting machine according to the invention 20 , which is designed here as a high-temperature superconductor synchronous machine. It includes a stator 21 and one against the stator 21 rotatable rotor 22 , the superconducting coil 23 has to generate the magnetic flux at rotor poles. For cooling the coils 23 is a cooling device according to the invention 1 . 1' or 1'' intended.

In particular, on ships such a configuration is advantageous, since it can lead to inclinations, in which the coolant must be promoted against gravity.

It should be noted at this point that it is the superconducting machine 20 can also be provided that the material structure 11 together with the rotor 22 rotated, so no additional rotation device 13 must be provided.

Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (10)

Cooling device ( 1 . 1' . 1'' ), comprising in particular a cold head ( 5 ) coupled condenser ( 4 ) for the liquefaction of gaseous coolant, an evaporator ( 8th ) for the evaporation of liquid coolant ( three ) for cooling an object to be cooled ( 9 ) and a heat pipe ( 7 ) for transporting the coolant ( three ) between the evaporator ( 8th ) and the condenser ( 4 ), wherein for transporting the liquid coolant ( three ) due to the capillary effect a wick-like material structure ( 11 ), characterized in that a rotation device ( 13 ) for rotation of the material structure ( 11 ) around one in the transport direction of the liquid coolant ( three ) through the heat pipe ( 7 ) lying axis of rotation is provided, wherein the material structure ( 11 ) is fanned on the evaporator side in the radial direction with respect to the axis of rotation. Cooling device according to claim 1, characterized in that the material structure ( 11 ) outside of an evaporator-side outlet region ( 19 ) and a condenser-side entry area ( 18 ) to the outside, in particular completely, from a shell ( 12 . 12 ' ) is surrounded. Cooling device according to claim 2, characterized in that the envelope ( 12 . 12 ' ) as a version of the material structure ( 11 ) acts and / or as a pipe ( 24 ) is trained. Cooling device according to one of the preceding claims, characterized in that the material structure ( 11 ) surrounded by a space for transporting gaseous coolant in the heat pipe ( 7 ) is guided. Cooling device according to one of the preceding claims, characterized in that the liquid coolant ( three ) from a container ( 2 ) for liquid coolant ( three ) in the material structure ( 11 ) penetrates. Cooling device according to claim 4 and 5, characterized in that the material structure ( 11 ) in one of a center axis of the heat pipe ( 7 ) deviating direction is performed. Cooling device according to one of claims 1 to 4, characterized in that the liquid coolant ( three ) on the material structure ( 11 ), in particular dripped, is. Cooling device according to claim 7, characterized in that the material structure ( 11 ) in one of a center axis of the heat pipe ( 7 ) deviating direction is performed. Cooling device according to one of the preceding claims, characterized in that the material structure ( 11 ) with the object to be cooled ( 9 ) is rotatable. Superconducting machine ( 20 ) comprising at least one for generating a magnetic flux at poles of a rotor ( 22 ) or stators ( 21 ) formed superconducting coil ( 23 ) and one for cooling the coil ( 23 ) formed cooling device ( 1 . 1' . 1'' ) according to one of the preceding claims.

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