WO2008040609A1

WO2008040609A1 - Refrigerating arrangement comprising a hot connection element and a cold connection element and a heat exchanger tube connected to the connection elements

Info

Publication number: WO2008040609A1
Application number: PCT/EP2007/059269
Authority: WO
Inventors: Marijn Pieter Oomen; Peter Van Hasselt
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-09-29
Filing date: 2007-09-05
Publication date: 2008-04-10
Also published as: KR20090077800A; US20090293504A1; ES2647681T3; DE102006046688B3; CN101523136A; EP2066991A1; KR101422231B1; EP2066991B1

Abstract

The invention relates to a refrigerating arrangement (100) comprising a hot connection element and a cold connection element (101, 103) and a heat exchanger tube arranged between said connection elements (101, 103). The heat exchanger tube (105) is to be at least partially filled with a liquid (106) that can be circulated in the heat exchanger tube (105) by a thermosiphon effect. The parts (102) to be cooled of a device, especially used in supraconductivity technology, are connected to the hot connection element (101), and a heat sink (104) is connected to the cold connection element (103). In order to thermally separate the connection elements (101, 103), the liquid (106) can be pumped out by means of a pipeline (107) connected to the inside of the heat exchanger tube (105).

Description

description

Cooling system with a hot and a cold connection element and a heat pipe connected to the connecting elements

The invention relates to a refrigeration system having at least one hot connection element, which is thermally connected to parts of a device to be cooled, a cold connection element, which is thermally connected to a heat sink, a heat pipe made of poorly heat-conducting material, which at a first end with the warm connection element and at a second end to the cold connection element is connected, and whose interior is at least partially filled with a circulating after a thermosiphon effect liquid.

A refrigeration system with the above-mentioned features is apparent, for example, from DE 102 11 568 B4.

Cooling systems, e.g. Cooling systems for superconducting magnets often have so-called bath cooling. For such bath cooling, a liquid refrigerant, e.g. Helium, with a temperature of typically 4.2 K are used. DE 10 2004 060 832 B3 discloses an NMR spectrometer whose superconducting magnet coil system has bath cooling. The cooling system of the NMR spectrometer is designed such that a circulating refrigerant detects various elements of the NMR spectrometer in its circulation path. By means of such a refrigerant circulation, a multiplicity of elements of the NMR spectrometer with different temperature levels can be cooled by means of a single refrig- erator.

For a bath cooling, however, large quantities of the corresponding refrigerant are necessary. In the case of a superconducting magnet, there is also the possibility that this may be exceeded, for example by exceeding a value for the corresponding superconducting material. critical current or a critical magnetic field loses its superconducting properties. In such a case, the superconducting material quickly generates a large amount of heat. The resulting heat leads to boiling of the refrigerant within the cryostat when cooling the bath. Large amounts of gaseous refrigerant leads to a rapid increase in pressure within the cryostat.

To counteract this problem while reducing the cost of the refrigerant, cooling systems are designed without a refrigerant bath. Such cooling systems can do without any refrigerant. The cooling capacity is introduced in this case only by solid-state heat conduction in the areas to be cooled. In such a cooling system, the areas to be cooled may be replaced by a so-called solid state cryobus of e.g. Copper connected to a chiller. Another possibility is to connect the areas to be cooled and the chiller to a closed piping system in which a small amount of refrigerant circulates. The advantage of such cooling systems without a refrigerant bath continues to be that they are easier to adapt to moving loads to be cooled as cooling systems, which have a refrigerant bath. Cooling systems without a refrigerant bath are therefore particularly suitable for superconducting magnets of a so-called gantry, as used in ion beam therapy for combating cancer. The cooling capacity can be provided in the cooling systems described above typically a chiller with a cold head in particular a Stirling cooler available.

A superconducting magnet in which a cold head with its second stage is directly mechanically and thermally connected to the support structure of a superconducting magnet winding can be seen for example from US Pat. No. 5,396,206. The necessary cooling capacity is directly transferred to the superconducting magnet by means of solid-state heat conduction in the superconducting magnet. introduced magnetic coils. If, however, a cold head has to be replaced, for example, for maintenance purposes, the abovementioned cooling device for a superconducting magnet has a decisive technical problem. During the exchange process, air or other gases may freeze at the cryogenic contact surface, in this case the superconductive winding support structure. Ice formed at these points leads to a poor thermal connection of the subsequently reused cold head with the holding structure of the winding.

To prevent freezing of gases at the cryogenic contact surfaces, they can be heated to about room temperature. This usually results in the entire parts of a device to be cooled, e.g. the entire superconducting windings of a magnet must be brought to room temperature before the cold head can be replaced. Especially for large systems, such a warm-up phase and the subsequent cooling phase can take a long time. This leads to long downtime of the system. The warm-up and cool-down phases continue to lead to a large consumption of energy.

Alternatively, the freezing of ambient gases at the deep-cold contact surfaces can be avoided by purposely flooding the space around these contact surfaces with gas. However, this is expensive and leads to a large consumption of purge gas or vaporized refrigerant for this purpose.

EP 0 696 380 B1 discloses a superconducting magnet with a cryogen-free refrigeration system. The disclosed refrigeration system has a thermal bus of good thermal conductivity material such as copper, which is connected to the superconducting magnet. The thermal bus can still be connected to two cold heads. The two cold heads are arranged symmetrically to the thermal bus. They can each be approached from opposite sides to the thermal bus. In this way one or both cold heads can be Fe be brought into thermal contact with the thermal bus. The cooling capacity is introduced in accordance with one or both cold heads in the thermal bus.

To replace one of the two cold heads of the known system this can be moved back mechanically by the thermal bus, whereby the corresponding cold head is also thermally separated from the thermal bus. In this case, the cooling capacity is only provided by the one remaining cold head. An exchange of the retracted cold head can now be done without the superconducting magnet must be heated. In the case of the refrigeration plant disclosed in EP 0 696 380 B1, however, the cold heads must be designed to be mechanically movable, which requires a large number of low-temperature-capable components and a corresponding, possibly interference-prone, mechanism.

JP 2000-146333 A discloses an apparatus and method for maintaining a cryocooler. Before replacing a cryocooler or cold head, a corresponding identical one is used

Cold head pre-cooled in a bath with liquid nitrogen. By pre-cooling the identical cold head, the components of the cold head can be brought to a comparable temperature as the corresponding components to be replaced. In this way, the cryogenic conditions within a plant whose cold head is to be replaced, can be kept almost unchanged.

DE 102 11 568 B4 discloses a refrigeration system with two cold heads, which are connected to the parts of a device to be cooled via a piping system in which a refrigerant can be circulated according to a thermosiphon effect. The piping system has a branch. At each end of the branches there is a refrigerant space, which is connected to a cold head. Liquid refrigerant decreases, starting from one of these refrigerant chambers, gravity driven to the parts of the device to be cooled, at which the heat transfer takes place. Gaseous refrigerant rises in the piping system again to the two cold heads, where it is reliquefied. Such a cycle of the refrigerant may take place in the piping system both in the case where only one cold head is operating and in the case where both cold heads are operating. If the refrigeration system is dimensioned in such a way that a single cold head applies the cooling capacity necessary for the parts of the device to be cooled, another cold head can be exchanged during operation of the refrigeration system. This is to minimize thermal losses

Pipe system between the junction and the refrigerant spaces, which are each connected to a cold head, made of poor thermal conductivity material. In this way, the losses can be limited by solid-state heat conduction. However, gaseous refrigerant will always rise to the point where there is no or cold head off. Thus, although the losses can be limited by solid-state heat conduction, but not the losses caused by circulating refrigerant.

DE 101 04 653 A1 discloses a mechanical heat switch, which consists of a first cup-shaped metal body, which can enclose a second metal body in a form-fitting manner. The first metal body has for this purpose a free end which, together with the outer jacket of the second

Metal body can form a positive connection. In the first pot-shaped metal body, a fourth metal body is introduced, a third metal body surrounds the cup-shaped first metal body from the outside surrounding. Upon heating of the fourth metal body, this expands and presses against the inner wall of the pot of the first metal body such that the free end of the first metal body moves and thereby releases the connection to the second metal body. In this way, the thermal contact between the first and the second metal body can be opened. During cooling of the first metal body, the third metal body, which surrounds the first metal body and forms a ring, contracts and presses the free end of the first metal body. gene the second metal body. In this way, the thermal switch can be closed.

The object of the present invention is to specify a refrigeration system in which the parts of a device to be cooled are connected to a heat pipe in which a liquid can be circulated by a thermosyphon effect, with a heat sink, wherein the parts to be cooled of a device should be largely thermally decoupled from the heat sink without a mechanical separation.

This object is achieved with the measures specified in claim 1. The present invention is based on the following considerations: The heat exchange between the heat sink and the parts of a device to be cooled takes place essentially by the liquid which can be circulated in the heat pipe according to a thermosiphon effect. For thermal separation of the heat sink from the parts of the device to be cooled, the heat pipe can be pumped off via a pipe connected to its interior. The heat pipe should be made of a poor thermal conductivity material at the same time. By these measures, the thermal connection between the heat sink and the parts to be cooled of the device is reduced to a defined by the Festkörperwärme- conductivity of the heat pipe low level. According to the invention, the refrigeration system should contain at least one hot connection element, which is thermally connected to parts of a device to be cooled, and a cold connection element, which is thermally connected to a heat sink contain. A heat pipe made of poorly heat-conducting material should be connected at a first end to the hot connection element and at a second end to be mechanically detachable with the cold connection element. The interior of the heat pipe should be at least partially filled with a liquid which can be circulated according to a thermosiphon effect. Furthermore, the refrigeration system should comprise a pipeline which is connected to a first end with the interior of the heat pipe and designed in such a way is that at least parts of the pipeline are geodetically higher than the liquid level. For the thermal separation of the connecting elements according to the invention, the liquid should be able to be pumped out of the heat pipe via the pipeline.

The advantages of a refrigeration system with the aforementioned features are to be seen in the fact that a heat transfer through the heat pipe is significantly reduced by the liquid is pumped from the interior of the heat pipe. In this way, the parts of a device to be cooled can be largely thermally decoupled from the heat sink without the need for a second heat sink and without having to mechanically move one or more heat sinks. If the heat sink, which is mechanically detachably connected to the cold connection element, removed from the refrigeration system, the cold connection element can heat up within a short time so far that in particular air or other gases contained in the ambient atmosphere only to a small extent on the surface of the cold Freeze connection element. Ice formation on the contact surfaces between the cold connection element and the heat sink can be largely avoided in this way. Due to the reduced formation of ice, the thermal contact when reinserting the heat sink will be much better than in the case in which there is significant ice formation at the contact surfaces. Furthermore, the cryogenic region in which the parts of the device to be cooled, due to the thermal decoupling, is prevented from penetrating into this region heat flows. In this way, even when replacing the heat sink to be cooled parts of a device at the desired low temperature. With the aforementioned measures, a refrigeration system can be specified, which allows even with a single heat sink use, without heating the parts to be cooled is necessary to exchange the heat sink or wait or remove temporarily. The refrigeration system according to the invention is particularly suitable for devices in the field of superconducting technology. Advantageous embodiments of the refrigeration system according to the invention will become apparent from the dependent of claim 1 claims. In this case, the embodiment according to claim 1 can be combined with the features of one of the subclaims or preferably also those of several subclaims. Accordingly, the refrigeration system according to the invention may additionally have the following features:

The parts of the device to be cooled can be arranged in an evacuatable cryostat and the second end of the pipeline can be outside the cryostat. Deep-frozen parts of a device can be thermally insulated from their environment particularly advantageously by means of an evacuatable cryostat. Such a thermal insulation represents a particularly effective insulation for cryogenic parts of a device. Especially in such cryogenic parts of a device, it is desirable to avoid ice formation on the contact surfaces of the cold connection element. The use of a

Refrigeration system according to the above embodiment is therefore particularly advantageous especially for devices with cryogenic parts.

- There may be a multi-stage refrigerator with a first and a second stage, wherein the heat sink may be formed by the second stage and the first stage may be mechanically detachably connected to a disposed within the cryostat heat shield. A multi-stage chiller is particularly suitable for cryogenic parts of a device to be cooled. It is particularly advantageous to use a heat shield as a further measure for thermal insulation. The thermal separation according to the invention of the parts to be cooled of a device from the second stage of the refrigerating machine is particularly advantageous, since the advantage of a thermal separation without moving parts comes into play particularly in mechanically complex cooling systems. At least parts of the refrigeration machine may be interchangeably mounted in an evacuable maintenance space separated from the evacuatable cryostat. With the help of another, separated from the evacuated cryostat, also evacuated maintenance space of the replacement of the chiller can be made without the vacuum of the cryostat must be broken. The maintenance process is particularly simple and effective in this way.

The liquid may be present as a two-phase mixture. When the liquid in the heat pipe is in two phases, circulation of the liquid in the heat pipe may occur, condensing gaseous liquid at the cold end of the heat pipe and vaporizing liquid liquid at the warm end of the heat pipe. In this way, the latent heat of the phase transition can be used for heat transport. However, a corresponding circulation can also be achieved in a single-phase liquid due to natural convection based on density differences.

The refrigeration system can be rotatable about an axis which runs essentially parallel to an axis of symmetry of the heat pipe. The heat pipe can furthermore have a larger cross-section in a first area, which is connected to the warm connecting element, than in a second area, which is connected to the cold connecting element. The parts of the heat pipe connecting the first and the second area may be configured such that condensed refrigerant can freely move to the first area under the influence of gravity in the second area. A refrigeration system with the aforementioned features can be used in particular advantageous for movable, in this case rotatably arranged to be cooled parts of a device. Due to the special design of the heat pipe the thermal contact between the chiller and the parts of the device to be cooled is guaranteed at any time even with a rotation of the parts to be cooled of a device.

The tubing may be connected at its ends near the axis of symmetry of the heat pipe to the heat pipe and the outside of the cryostat. The pipeline can furthermore have at least one intermediate axis in the direction of travel. By means of an embodiment of the pipeline as described above, upon rotation of the parts to be cooled, a device can be prevented which advances refrigerant through the pipeline to the warm end of the pipeline, which is fastened outside the cryostat. In this way it is avoided that a circulation of the refrigerant in the pipeline takes place between the deep-cold area located inside the heat pipe and the end of the pipe which is arranged outside the cryostat. Particularly advantageous can be prevented by a circulation of the refrigerant as described above by the above-described embodiment of the pipeline heat losses.

The intermediate region of the pipeline can have a V-shaped course in the direction of the axis A. A V-shaped bent pipe represents a particularly simple and effective embodiment of the pipeline.

- The heat pipe can be configured substantially in the shape of a truncated cone. By forming the heat pipe in the form of a truncated cone, a particularly simple inexpensive and effective form of the heat pipe can be specified.

The refrigeration system may comprise an additional cooling system, which has at least the following features: A refrigerant space which communicates with the cold connection element connected is; a supply line through which the refrigerant space can be filled from a geodetically higher location outside the cryostat with a second refrigerant; a piping system which is thermally connected over a large area with the parts to be cooled of the device and in which the second refrigerant is conditionally circulated by a thermosiphon effect; an exhaust pipe through which gaseous second refrigerant can escape from the piping system. By means of an additional cooling system with the aforementioned features, an acceleration of the cooling phase can be achieved, in particular for large masses to be cooled. By filling a second refrigerant from a geodetically higher location outside of the cryostat into the refrigerant space via the supply line, additional cooling capacity is provided for the cooling agent

Parts of a facility provided. Optionally, evaporating second refrigerant can escape via the exhaust pipe from the piping system. In this way, the formation of an overpressure in the piping system is prevented. Within the piping system, the second refrigerant can circulate after a thermosiphon effect, thus providing effective cooling.

The connecting elements can be made of a good thermal conductive material, preferably of copper. The heat pipe may be made of a material having a thermal conductivity less than that of copper, preferably of stainless steel. Such a configuration of the connecting elements made of a good thermally conductive material such as copper, a special effective thermal coupling can be achieved both to the heat sink as well as to be cooled parts of the device. The thermal conductivity of the heat pipe is mainly due to the circulating within the heat pipe refrigerant. If the heat pipe itself is made of a poorly heat-conductive material, such as stainless steel, a particularly large reduction in the thermal conductivity can be achieved by pumping off the refrigerant. The device may be a gantry device for radiotherapy, and the parts to be cooled may be the magnets of the gantry for deflecting a particle beam. The refrigeration system according to the invention is particularly suitable for a gantry, since the magnets to be cooled are rotated about an axis of rotation of the gantry.

Further advantageous embodiments of the refrigeration system according to the invention will become apparent from the claims not mentioned above and in particular from the drawing below. In the drawing, preferred embodiments of the refrigeration system according to the invention are indicated in a slightly schematized form. 1 shows the cross section of a refrigeration system,

Figure 2 shows the cross section of a rotatable refrigeration system and Figure 3 shows the cross section of a rotatable refrigeration system with an additional cooling system.

Parts corresponding to the figures are each provided with the same reference numerals. Parts that are not detailed are general state of the art.

Figure 1 shows the schematic structure of a refrigeration system 100 according to one embodiment. A cryostat 108 contains the parts 102 to be cooled of a device. The device parts to be cooled 102 may be, for example, the magnet windings of a superconducting magnet or other parts of the superconducting technique. Inside the cryostat 108, a thermal shield 112 is attached to improve the thermal insulation. The cooling capacity for the parts to be cooled 102 of the device is provided by a refrigerator 109, such as a cold head or a Stirling cooler. Preferably, a cold head can be used, which operates on the Gifford-McMahon principle. Such a two-stage chiller can be thermally connected to the heat shield 112 according to the present embodiment with its first stage 111. The connection between the first stage 111 of the refrigerator 109 and the heat shield 112 may preferably be a releasable mechanical connection, such as a screw or clamp connection, which simultaneously ensures good thermal contact of the components. The second stage 110 of the refrigeration machine 109 represents the actual heat sink 104 of the refrigeration system 100. The second stage 110 of the refrigerator 109 is thermally connected to a cold connection element 103. The corresponding connection may preferably be a screw connection. That is, the refrigerator 109 is detachably screwed with its second stage 110 in the cold connection element 103. Any other mechanical connection which is releasable and at the same time ensures good thermal contact between the second stage 110 of the refrigerator 109 and the cold connection element 103 is also suitable for the embodiment shown in FIG. The connecting elements 101 and 103 may be part of the parts 102 to be cooled of a device or the heat sink 104. They can continue to be integrated into the corresponding components or permanently connected to them.

The chiller 109 is partially located in a separately evacuable maintenance room 113. This maintenance room 113 is separated from the rest of the evacuatable space of the cryostat 108. The cold connection element 103 is connected to a heat pipe 105 with good thermal conductivity and preferably also mechanically. On the opposite side, the heat pipe 105 is connected to a warm connection element 101. This compound is also designed to conduct heat well and may preferably also be a mechanical connection. The warm connection element 101 is in turn connected to a good heat-conducting with the parts to be cooled 102 of a device. Within the heat pipe 105 is a liquid 106, which can circulate in the heat pipe 105 in accordance with a thermosiphon effect. The heat pipe 105 itself, however, consists of a poorly heat-conducting material.

If the heat pipe 105 is completely filled with the liquid, this can be in the upper cold area of the heat pipe Due to the differences in density of the liquid 106, a circulation after the so-called. Thermosiphon effect can be adjusted in the heat pipe 105, which is a heat transport from the parts to be cooled 102 of the device the heat sink 104 causes.

Furthermore, the heat pipe 105 may be only partially filled with a liquid 106. In this case, a circulation of the liquid 106 in two different

Set phases, e.g. liquid-gas. Accordingly, gaseous liquid is liquefied in the portion of the heat pipe 105 which is in thermal contact with the cold joint 103. Condensed liquid 106 moves in a gravity-driven manner into the part of the heat pipe 105 shown below in FIG. 1, which is in thermal contact with the hot connection piece 101. In this part of the heat pipe 105, the liquid 106 delivers the cooling capacity to the hot connector 101 (and thus also to the parts of the device 102 to be cooled), whereupon gaseous liquid 106 rises again into the upper part of the heat pipe. In this case, the cold connector 103 acts as a condenser and the hot connector acts as an evaporator. In this way, a good thermal connection between the refrigerator 109 and its second stage 110 and the parts to be cooled 102 of a device can be ensured.

During operation of a refrigeration system 100, the necessity may arise that a refrigeration machine 109 must be replaced, for example, for maintenance work or due to a defect. Before the refrigerator 109 is removed from the refrigeration system 100, the liquid 106, which is located within the heat pipe 105, is pumped out via a pipe 107 leading to the outside. It is sufficient in many cases to pump out the liquid 106 for the most part from the heat pipe 105; but it can also be completely removed from the heat pipe 105. By removing the liquid 106 from the heat tube 105 is removed, the thermal conductivity of the heat pipe 105 is significantly reduced. Between the cold connection element 103 and the warm connection element 101, a heat conduction takes place in the following only as a result of solid-state heat conduction via the material of the heat pipe 105. If the heat pipe 105 made of a poor thermal conductivity material such as stainless steel, the thermal conduction between the connecting elements 101, 103 can be reduced to a minimum. As materials for the heat pipe 105, in addition to stainless steel, various plastics, ceramics or other low-temperature suitable materials can be used. Another measure for minimizing the heat conduction is to make the heat pipe 105 particularly thin-walled and / or with small geometrical dimensions.

After the liquid 106 has been pumped out of the heat pipe 105 via the pipe 107, the maintenance room 113 can be ventilated. Due to the ambient air flowing into the maintenance space 113, the cold connection element 103 as well as the previously cold parts of the cooling machine 109 begin to heat up. The maintenance room 113 can also be flooded with a special purge gas, such as dried air, nitrogen or helium. After the maintenance room 113 has been ventilated, the refrigerator 109 can be removed from the refrigeration system 100. The previously deep-cold connection element 103 is thermally decoupled from the remaining still very cold parts, in particular the warm connection element 101 and the parts 102 to be cooled of a device and will therefore heat up quickly to a temperature close to room temperature. Since the cold connection element 103 is heated as described above, ice formation by condensing gas, such as preferably ambient air, is largely avoided. When reseating the refrigerating machine 109, therefore, a good thermal and mechanical contact between the second stage 110 and the cold connection element 103 is ensured. Superconducting magnet windings are particularly suitable for irradiation systems, such as those used in particle therapy eg for combating cancer. Such superconducting magnet windings are preferably mounted in a so-called gantry, which is rotatable about a fixed axis.

FIG. 2 shows a further exemplary embodiment of the refrigeration system, generally designated by 100, wherein the entire refrigeration system 100, including the parts 102 to be cooled, is surrounded by a

A axis A are arranged rotatable. According to the embodiment of the refrigeration system 100 shown in FIG. 2, the parts 102 to be cooled are located in a cryostat 108, which additionally has a heat shield 112. The refrigerator 109 is preferably designed rotationally symmetrical with respect to a further axis B. The refrigerator 109 is housed in a maintenance room 113, which is evacuated separately from the cryostat 108. The first stage 111 of the refrigerator 109 is connected to the heat shield 112, the second stage 104 of the refrigerator 109 is connected to the cold

Connecting element 103 connected. The heat pipe 105 is located with a first part 202 in thermal, preferably also mechanical connection with the cold connection element 103. Another part 201 of the heat pipe 105 is in thermal, preferably also mechanical contact with the warm connection element 101 Heat pipe 105 has a smaller cross section than the second part 201 of the heat pipe 105. The part 203 of the heat pipe 105, which connects the first part 202 and the second part 201 of the heat pipe 105, is configured in such a way that condensed liquid 106 can pass unhindered from the first region 202 into the second region 201 due to gravity , The entire heat pipe 105 may preferably have the shape of a truncated cone closed on both sides. Such a heat pipe

105 may further be connected to the refrigerator 109 so that the axis of symmetry of the truncated cone coincides with the axis B. In the area of this axis B, a pipe 107 is connected to the heat pipe 105. Through this pipeline, the liquid 106 can be pumped out of the heat pipe 105. The pipeline 107 has such a shape that any liquid 106 entering the pipeline 107 from the heat pipe 105 can not pass unhindered to the outer part of the pipeline 107 which is in communication with the cryostat 108. For this purpose, the pipeline 107 has a part 204 bent in the direction of the axis A. By such a design of the tube 107 can be prevented even with a rotation of the entire refrigeration system 100 about the axis A that liquid 106 passes through the pipe 107 in constant contact with the outer part of the pipe 107.

As described in connection with FIG. 1, the liquid 106 can be pumped out of the heat pipe 105 through the pipeline 107. In this way, a thermal separation between the parts to be cooled 102 of a device and the heat sink 104 is achieved. In order to be able to exchange the refrigerating machine 109, for example for maintenance purposes, even in such a refrigeration system 100 that can be rotated about an axis A, the working space 113 is aerated after the liquid 106 has been pumped off. In the event that the heat shield 112 has a rigid connection with the cryostat 108, the parts of the working space 113, which are arranged between the mounting flange of the first stage 111 of the refrigerator with the heat shield 112 and the condenser 103, can be designed to be flexible. Such a flexible embodiment can be carried out, for example, with the aid of a bellows. In order to enable a separation between the second stage 110 of the refrigerator 109 and the condenser 103, the condenser 103 may be movable along the axis B due to a flexible configuration of the heat pipe 105. The heat pipe 105 may also have a bellows for this purpose. Figure 3 shows another embodiment of a generally designated 100 refrigeration system. The refrigeration plant 100 shown in FIG. 3 is expanded by an additional cooling system compared to that shown in FIG. A refrigerant space 301 is in thermal, preferably also in mechanical contact with the cold connection element 103. This refrigerant space 301 can be filled by a feed line 302 from a geodetically higher location. As the refrigerant, a same or similar refrigerant can be used as it is used for the heat pipe 105. Usable are, for example, helium, neon or nitrogen. To the refrigerant space 301, a piping system 303 is connected, which is connected over a large area with the parts to be cooled 102 of a device. In this way, additional cooling capacity can be brought to the parts to be cooled 102 of a device. In this way, the cooling times, for example, for a superconducting magnet can be significantly reduced. Optionally, in the piping system 303 evaporating refrigerant can escape via an exhaust pipe 304 from the piping system 303. In this way, an overpressure in the piping system 303 is avoided.

The auxiliary cooling device may e.g. be used so that the parts to be cooled 102 of a device first with nitrogen, which is inexpensive and readily available, are pre-cooled before using the chiller 109, the parts to be cooled 102 are cooled to even lower temperatures. For the use of additional cooling device, it is technically necessary to stop the refrigeration system 100 in its possible rotation about the axis A, or at least to move so slowly that in the piping system 303, a gravity-driven refrigerant circuit, which is based on a thermosiphon effect, can set ,

Claims

claims

1. Refrigeration system (100) with at least a. a hot connector (101) thermally connected to parts (102) of a device to be cooled, b. a cold connector (103) thermally connected to a heat sink (104), c. a heat pipe (105) made of poorly heat-conducting material, which is connected at a first end to the hot connection element (101) and at a second end mechanically detachably connected to the cold connection element (103) and the interior at least partially with one after a Thermosiphon effect is circulated liquid (106) filled, and d. a conduit (107) connected at a first end to the interior of the heat pipe (105) and configured such that at least portions of the conduit (107) are geodetically higher than the fluid level, e. wherein, for a thermal separation of the connecting elements (101, 103), the liquid (106) can be pumped off via the pipeline (107).

2. refrigeration system (100) according to claim 1, characterized marked, that the parts to be cooled (102) of the device in an evacuable cryostat (108) are arranged and the second end of the pipe (107) outside of the cryostat (108) ,

3. refrigeration system (100) according to claim 2, characterized in that a multi-stage refrigerator (109) having a first stage (111) and a second stage (110) is provided, wherein the heat sink (104) from the second stage (110) is formed, and the first stage (111) is mechanically detachably connected to a within the cryostat (108) arranged heat shield (112).

4. refrigeration system (100) according to claim 3, characterized in that at least parts of the refrigerator (109) are removably mounted in an evacuated by the cryostat (108), evacuated maintenance room (113).

5. refrigeration system (100) according to one of the preceding claims, characterized in that the liquid (106) is present as a two-phase mixture.

6. refrigeration system (100) according to one of the preceding claims, characterized in that a. a rotation about an axis (A) is provided, which runs substantially parallel to an axis of symmetry (B) of the heat pipe (105), and b. the heat pipe (105) has a larger cross section in a first area (201) connected to the warm connection element (101) than in a second area (202) connected to the cold connection element (103), and Parts (203) of the heat pipe connecting the first (201) and the second region (202) are configured such that refrigerant (106) condensed in the second region (202) unhindered under the influence of gravity in the first region (201) can get.

7. refrigeration system according to claim 6, characterized in that the pipe (107) at their ends near the axis of symmetry

(B) of the heat pipe (105) to the heat pipe (105) and the outside of the cryostat (108) is connected, and the pipeline (107) in the direction of at least one of the axis (A) near intermediate region (204).

8. refrigeration system according to claim 7, characterized in that the intermediate region (204) in the direction of the pipe (107) has a V-shaped bend in the direction of the axis (A).

9. refrigeration system according to one of claims 6 to 8, characterized in that the heat pipe (105) is formed substantially in the shape of a truncated cone.

10. Refrigeration system according to one of the preceding claims, characterized by an additional cooling system, comprising a. a refrigerant space (301) connected to the cold connection member (103), b. a supply line (302) through which the refrigerant space (301) can be filled with a second refrigerant from a geodetically higher location outside the cryostat (108), c. a piping system (303), which is thermally connected over a large area with the parts of the device to be cooled (102) and in which the second refrigerant is circulated due to a thermosiphon effect, and d. an exhaust line (304) through which gaseous second refrigerant can escape from the piping system (303).

11. refrigeration system according to one of the preceding claims, characterized in that the connecting elements (101, 103) made of a good heat conductive material, preferably made of copper.

12. A refrigeration system according to one of the preceding claims, characterized in that the heat pipe (105) made of a material having a thermal conductivity less than that of copper, preferably of stainless steel.

13. Refrigeration system according to one of the preceding claims, characterized in that the device contains superconducting parts.

14. Refrigeration system according to one of the preceding claims, characterized in that the device is a gantry device for radiotherapy.

15. Refrigeration system according to claim 14, characterized in that the parts to be cooled (102) are magnets, preferably superconducting magnets, for deflecting a particle beam.