DE1967744U - DEVICE FOR GENERATING COLD AT LOW TEMPERATURES AND / OR LIQUIDING AN AGENT. - Google Patents

Description

Device for generating cold at low temperatures and / or for liquefying an agent.

The furnace "refers to a device for generating cold and / or for liquefying an agent using a compression device with the "at higher average! temperature." an agent Ms is compressed above the critical pressure, and their outlet via one or more heat exchangers or regenerators is connected to the inlet of an expansion device, while the outlet for expanded agent via the heat exchanger or regenerators connected to the inlet of the compression device. . - - ■

It is known to provide a means of achieving low temperatures to compress at higher! temperature and at lower {temperature to expand. The expansion of the agent can be in an expansion machine or in a throttle device.

In the present! Inflation, to below an expansion machine to a machine to be understood in the means can be virtually expanded adiabatically reversible _f This is in contrast to a throttle device, in which the expansion Although adiabatisoh, but does not take place reversibly. -

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An expansion machine is only useful if no phase transition of the agent occurs during the expansion. at Phase transition occurs namely cavitation phenomena, while the efficiency of the machine is impaired. Until now it has been generally assumed that machines of this type can only be used if the expansion temperature is not carter is the critical temperature of the agent.

To achieve very low temperatures and also to liquefy a means is then generally used as a throttle device. The disadvantage of such a throttle device however, it is that the expansion occurs with a much lower efficiency.

In order to eliminate this disadvantage, it has already been proposed that to compress the agent up to above the critical pressure, then to cool it down to below the critical temperature and finally to relax to a pressure that is also above the critical pressure of the agent. This of course occurs during the relaxation no phase transition, so that the relaxation can take place in an expansion machine. One downside to this Method is, however, that the cooling capacity is low.

The hiring is based on the knowledge that the means are indeed in an expansion machine can be relaxed to a pressure which is below the critical pressure of the agent, if care is only taken that the agent is cooled by the expansion to such an extent that no phase transition occurs during the expansion occurs. After the expansion, the heat of evaporation can then be reduced gain in whole or in part as cooling capacity.

In order to be able to make use of this knowledge, see the device described at the beginning according to the innovation characterized by the fact that the relaxation device consists essentially of an expansion machine, and that

between the outlet of the expansion machine and the an evaporator is present in the heat exchangers mentioned, in which the relaxed means is in heat exchange with a point to be cooled, and that one or more in the evaporator Cooling channels are provided, one end of which to the outlet for compressed medium of the heat exchanger and the other End is connected to the inlet of the expansion machine.

Another advantageous embodiment of the device according to the innovation is that the expansion machine from at least one cylindrical body with a "movable double-acting piston-shaped body" in this, this piston-shaped body, by means of the two piston surfaces, the volume of a warmer room, which is in operation has a higher mean temperature, and a colder room that has a lower mean temperature during operation has, able to change, while these two spaces interrelate are connected, in this connection preferably at least one cooler and at least one regenerator are located, while the compression device can be brought into connection with the v / poorer space via controllable valves, a control device being provided is to operate the controllable valves so that the inlet valve is opened when the warmer room is close to the has the largest volume, and is closed after a piston-shaped bodies in the direction of the warmer room has set in motion, after which the control device slowly opens the outlet valve when the colder room is almost has the largest volume and keeps it open until the colder room has almost the smallest volume. This device is very suitable for reaching low temperatures.

In this case, the supply line for compressed medium connected to the warmer room is expediently in heat exchange with a cold source, e.g. a cold gas cooling machine.

The advantage of having a cooler in the connection between the colder and warmer liaum or in the feed line for compressed medium is that the warmer room has an average temperature which, depending on the temperature of the coolant, can be lower than the room temperature, so that the The temperature difference between the colder s and the warmer border is less large and the regenerator is not so heavily loaded. These coolers also take care of the dissipation of the compression heat generated.

According to a further advantageous embodiment, there are several in the connection between the warmer and the colder room Regenerators added, the agent passing through a cooler on its way from one regenerator to the other.

With a further, in particular "for liquid se r ζ eugung a suitable embodiment is in the connection between the warmer and the colder space between the last regenerator and the colder room is provided with a cooler, which consists of one or more cooling channels, which lead into a bath from below low Pressure boiling agent are exchanged. Here, the colder room is useful with a drain for liquid, under low Pressure boiling agent provided.

It is useful if the drain for liquid under low pressure boiling means through a line with the liquid bath is connected, with controllable valves in this line and in the connection * between the warmer and the colder room are attached.

The inflation is explained in more detail below with reference to the drawing.

fig. 1 schematically shows a temperature-entropy diagram which the innovation is basically explained.

Me Fig. 2, -3 and 4 show se nematically three different according to the innovation trained devices for generating cold at low! temperatures.

The fig. Figures 5 and 6 schematically show two further devices according to the innovation for generating cold "at very low levels Temperatures at which devices as an expansion machine a cylinder with a double-acting piston movable in it is used, the spaces on both sides of this Pistons have different average temperatures and are connected to one another via a regenerator stand.

! Fig. 1 shows a TS diagram. In this IS diagram there is a Cycle shown. This circuit comprises an isothermal compression from point 1 to point 2. In point 1 is the pressure below its critical value, in point 2 above this critical value. The condensed medium then becomes cooled down to point 3 with constant pressure. At this point the compacted medium has a temperature which is close to is equal to the boiling point of the relaxed agent. Then the agent is in an expansion machine from point 3 to Point 4 relaxed. At point 4, the pressure of the medium is lower than the critical pressure, and the temperature is also lower than the critical temperature. Still none arise Difficulties as a result of a so-called "water hammer" in ■ -. ' the expansion machine, because there is no phase transition. From point 4 on, the agent, e.g. in a throttle valve, brought into the state of point 5. At this point the steam begins to form. The remedy is now absorbing heat from state 5 to state 6. The heat of evaporation forms the cooling capacity · From point 6, the evaporated Medium warmed up again, e.g. in heat exchange with compressed medium until it is back to its original state is located. The strange thing about this cycle is that, while

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one previously v with a particular circuit © the right side in the circuit according to the innovation, the relaxation n forth in the I ¹ IUs sigkeits-vapor region penetrated the left of the liüssigkeits steam Bereioh takes place without phase transition, which in the evaporator of Ilüssigkeits-Damff - Area is traversed from left to right. .-. "-"".-.:;.

Another surprising aspect of this cycle is that the expansion takes place in an expansion machine. It would the most obvious thing to do is to perform the relaxation in a throttle valve. However, this would be a considerable result in poorer cooling performance. The mean would follow the line of constant enthalpy from point 3. This line is indicated by dashed lines in the figure. The course of this line clearly shows that part of the Cooling capacity is lost.

Fig. 2 shows schematically a device for generating Cold at low temperatures. This device includes a compressor 1o. A discharge line connects to this compressor 11 for compacted medium. In this line there is a buffer space 12, behind which the discharge line a heat exchanger 13 passes through. After passing through the heat exchanger 13, the line 11 leads to an expansion machine 14, at the outlet of which a line 15 is connected. A throttle valve arranged in this opens into a vessel 17. A snake 18 is arranged in this vessel 17 through which an agent to be cooled can be passed through. A return line 19 is also connected to the G-efäß 17, in which there is a buffer space 2o. The line 19 leads via the heat exchanger 13 back to the inlet of the compressor 1 ο,

The mode of operation of this device is as follows. The compressor 1ο compresses a medium, e.g. hydrogen or helium, up to the critical pressure. This compressed medium flows through line 11 to heat exchanger 13, in which

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it in heat exchange with relaxed means almost "up to the Boiling temperature of this relaxed agent is cooled. Then the agent is in the expansion machine 14 to below the relaxed critical pressure. Thereafter, the agent is through the throttle valve 16, in which its pressure is reduced somewhat if necessary is fed to the vessel 17. In this vessel 17 ″ there is a boiling liquid medium. This evaporates in that it is in heat exchange with the agent to be cooled flowing through the coil 18. That evaporated Medium flows back through line 19 to compressor 1o. The expansion machine can be both turbine and be a piston expansion machine.

The start of the process can be done in Pig. 2 cause difficulties because the compressed medium in the heat exchanger 13 is not cooled sufficiently, so that water hammer occurs in the expansion machine. U _m this may prevent some condensate can be poured into the apparatus at the start-up of the machine, the cooling concerned.

The start-up problem can also be solved in other ways namely, that during start-up the relaxation in a diosel valve connected in parallel to the expansion machine is carried out. Such a device is shown schematically in FIG. This device is different differs from that in Pig. 2 device shown, as it contains a second throttle valve 21 which is received in a line. This line is connected to a three-way valve 23 the line 11 connected for compressed medium. During the start-up of the device, the three-way valve 23 is in a Bred position in which the compressed medium flows into the line 22, so that its pressure in the throttle valve 21 when the device has cooled down sufficiently,

the three-way cock 23 is adjusted so that all the compressed agent in the expansion machine 14 is relaxed. The mode of operation of this arrangement corresponds to that of the Pig device. 2 _.:

Mg. 4 shows a device for generating cold at low temperatures Temperatures at which, if necessary, a certain amount of liquid agent can be drained off. If liquid Medium is drained, this means that the heat exchanger 13 is no longer in equilibrium. That condensed The agent is then no longer adequately cooled in the heat exchanger. In order to be sufficiently deep for the expansion To maintain the temperature of the compacted medium, part of the cold provided is used for cooling the compacted medium used. For this purpose there is a cooling coil in the liquid bath 17 24 is provided, one end of which is connected to the conduit 11 for compressed medium and the other end of which is connected to the inlet the expansion machine is connected. This again results in a well-functioning device for generating cold at low temperatures, which can optionally be withdrawn via the outlet 25 liquid agent.

fig. 5 shows a device for generating cold at low temperatures, which is a somewhat modified expansion machine contains. The device consists of a compressor 5o to which a discharge line 51 for compressed medium is connected. The discharge line 51 is connected to a buffer vessel 53 via the heat exchanger 52, while the supply line 54 is connected to a buffer vessel 55. The buffer vessels 53 and 55 are connected to a common via controllable valves 56 and 57, respectively Line 58 connected. This line is attached to a cylinder connected, in which a displacer 61 is movable. The displacer 6o separates two rooms 61 and 62. The rooms 62 and 61 stand above a cooler 63, a regenerator 64 and a Evaporator 65 in communication with one another. The room 61 has a higher temperature than the room 62.

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The mode of action of this TTorrieliitiiag is consequent. When the displacer 6o almost - '. "Assumes the lower position, a control device (not shown) opens the valve 56, so that compressed medium enters the space 61 through the line 58. Then the displacer 6o moves close to the top, so that the medium out the room 61 is conveyed to the room 62. The agent gives off heat to the / cooler 63 and the regenerator 64, so that it reaches the room 62 at a temperature which is almost the same as the boiling point of the relaxed agent has reached the topmost position, the valve 56 is closed and the valve 57 is slowly opened. The agent is relaxed in the bar 62. Then the displacer 6 © moves down again. The relaxed agent evaporates in the evaporator 65 and flows over the regenerator 64 and the cooler 65 with heat absorption back to space 61. ν:

The temperature that prevails in room 61 depends on the cooler. This can be a common water cooler, so that the temperature of the room 61 is approximately room temperature. However, it is also possible to use a cold gas cooling unit as a cooler, which keeps the space 61 at 8o K, for example. This of course means a considerably lower load on the regenerator. ν:

Another embodiment of the device explained above is shown in Pig, 6. With this device it is possible to drain liquid agent. In this embodiment, two regenerators 66 and 67 and two coolers 68 and 69 are located in the connection between rooms 61 and 62. Furthermore, the agent is passed through a cooling coil 7o on the way to room 62 near the passage through the last regenerator 67, which is immersed in liquid under low pressure boiling agent in a vessel 71. The cooling coil is via a line 72 with a

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controllable valve 73, with the space 62 in connection. The skirt also connects to the vessel via a liquid discharge line 74 71 in connection. A controllable valve 75 is installed in this line 74. The vessel 71 is further with an outlet 76 provided for liquid means.

The operation of this device is as follows. When the displacer is in the lowest position, the valve 56 is opened. The pressure in the spaces 61 and 62 becomes supercritical as a result. The displacer βο then moves upwards, so that agent is conveyed from the space 61 to the space 62. During this promotion, the agent flows through the cooler 68, the regenerator 66, the cooler 69 and the regenerator 67. After this regenerator, the already strongly cooled agent is passed through the cooling coil 7o immersed in the boiling agent, whereupon it passes through the open valve 73 into the Expansion space 62 flows in. When the displacer 6o assumes the uppermost position, the valve 56 is closed and the valve 57 is slowly opened. As a result, the agent relaxes, so that boiling liquid appears in space 62. When the valve 75 is opened, this liquid flows to the vessel 71. In order to prevent the liquid from penetrating into the line 72, the valve 73 is closed at the same time. The vapor formed in the vessel 71 can pass through the check valve 77, the regenerator 67, the cooler 69, etc. flow back to room 61. When the displacer 6o has reached the lowest position, the valve 57 is closed and the valve 58 is opened and the new cycle begins again. You are free to choose the temperatures of the coolers 68 and 69. Pur a device to be compressed by means of the helium, the cooler 68 may have a (temperature of 6o ° K, while the cooler 69 has a temperature of 15 K ^0.

It is also possible to have the cooler 68 not in the connection between the spaces 61 and 62, but to be installed in the feed line for the compressed medium. The latter has the advantage

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Part that the compression mechanism, the heat exchange rather and the cooler can be arranged separately from the expansion unit. This is especially important if you are hindered by a lack of space at the point where the cold is to be drawn off.

Although it is assumed in the exemplary embodiment that the supply valve 56 is closed when the yawing device 60 occupies the top layer, this valve can also be closed during the upward movement of the Terdrängers.

The innovation offers the possibility of using proportionately high efficiency and cold by means of a relatively simple device at very low temperatures to create.

Claims (1)

Protection claims : 1. Device for generating cold "at low temperatures and / or for liquefying an agent using £, a compression device, with the higher middle The temperature a medium to above the critical pressure. ^ tet, and its outlet via one or more heat exchangers or regenerators are connected to the inlet of an expansion device, while the outlet for expanded means connected via the heat exchangers or regenerators to the inlet of the compression device is, characterized in that the expansion device consists essentially of an expansion machine, and an evaporator is provided between the outlet of the expansion machine and the heat exchangers mentioned, in which the relaxed means in with a place to be cooled Heat exchange is located. ^ 2. Apparatus according to claim 1, characterized in that one or more cooling channels are provided in the evaporator, one end of which to the compressed medium outlet of the heat exchanger and the other end of which to the inlet the expansion machine is connected. 3. Device according to claim 1 or 2, characterized in that * ■■. that the expansion device from an expansion machine and a throttle device λ connected in series with this tion exists. 4 * device according to claim 1, 2 or 3, characterized in that that the device has a throttle device that can be switched parallel to the expansion machine and on contains a control device that controls the valves in - 13- " exciting central current operated so that during start-up the device of the means.trom essentially through the Throttle device goes through, during normal Operation flows through the expansion machine. \ 5 · Device according to one or more of claims 1 to 4 »characterized in that the expansion machine consists of £ at least one cylinder with a "movable" cylinder in it double-acting piston-shaped body, which with the two piston surfaces the volume of a warmer Seams, which has a higher average temperature during operation, and a colder room, which has a has a lower mean temperature, is able to change, preferably in the connection of these two rooms at least one cooler and at least one regenerator are provided, the compression device over controlled valves can be connected to the warmer room, and a control device is available is to control the controlled valves so that the *, Inlet valve is opened when the warmer room is close to has the largest volume, and is closed after the piston-shaped body has started to move into To move towards the warmer room, after which the control device slowly opens the outlet valve when the colder room has almost the largest volume and keeps it open until the colder room has almost the low-ν most volume has. λ 6. Apparatus according to claim 5, characterized in that the supply line connected to the warmer room stands for compressed medium in heat exchange with a cold source, e.g. a cold gas mill. 7. Device according to claim 5 or β, dadurGli gelEennzeleluiet, that in the connection between the warmer and the colder A plurality of regenerators are provided along the edge, the means in each case on its way from one to the next regenerator flows through a cooler. 8. Device according to claim 5, β or 7, characterized in that that in the connection between the warmer and the Colder tree between the last regenerator and the colder room a cooler is provided, which consists of a or a plurality of cooling channels "immersed in a bath of low-pressure boiling agent. 9. Apparatus according to claim 8, characterized in that the colder space with a drain for liquid below low pressure boiling agent is provided. 1o. Device according to Claims 8 and 9, characterized in that that the drain for liquid under low Pressure boiling agent through a line to the liquid bath is connected, in this line and in the connection between the warmer and the colder Room controllable valves are attached.