JPWO2013154185A1 - Cooling device for high temperature superconducting equipment and method for operating the same - Google Patents

Abstract

The cooling device (1) for high-temperature superconducting equipment according to the present invention has a secondary heat for exchanging heat between the turbo compressor (2), the main heat exchanger (3), the expansion turbine (4), and the refrigerant gas and the coolant. An exchanger (5), a circulation pump (7), a temperature measuring means (10) for measuring the temperature of the coolant, a first closed channel (L1), and a second for circulating the coolant. A sub-heat exchanger (5) having a path through which the refrigerant gas flows in parallel, and a first heat exchange section (5a) that exchanges heat between the refrigerant gases. And a second heat exchanging part (5b) for exchanging heat so that the refrigerant gas and the cooling liquid face each other.

Description

The present invention relates to a cooling apparatus for high-temperature superconducting equipment and an operation method thereof.
This application claims priority on April 13, 2012 based on Japanese Patent Application No. 2012-092079 for which it applied to Japan, and uses the content here.

  HTS equipment such as a transformer, a power transmission cable, and a motor using high temperature superconducting (hereinafter referred to as “HTS”) needs to be cooled to about 60 to 80 K in order to maintain a superconducting state. In order to maintain the superconducting state, a cooling system (refrigerator) is indispensable, and recently, a refrigerator having a refrigerating capacity of about 2 to 10 kW is required. The HTS device is cooled by, for example, liquid nitrogen, and this liquid nitrogen is circulated by the liquid nitrogen circulation device in a subcooled state. The liquid nitrogen in the liquid nitrogen circulation device is cooled by a refrigerator.

  The subcooled state refers to a state in which the liquid temperature is lower than its saturation temperature. For example, in the case of liquid nitrogen at atmospheric pressure, liquid nitrogen having a temperature from the boiling point (about 77 K) to the freezing point (about 63 K). The state of. The saturation temperature refers to a temperature at which the pressure of a certain liquid becomes equal to the saturation vapor pressure.

  As a refrigerator required for HTS equipment, not only its size but also cooling performance such as cooling temperature, refrigeration capacity, and refrigeration efficiency are important. The GM refrigerating machine or Stirling refrigerating machine (60-80K, 0.1-0.6 kW) cannot be used. In addition, it is difficult to develop a GM refrigerator and a Stirling refrigerator having a refrigeration capacity of about several kW because a heat exchanger provided in the refrigerator becomes a problem.

As a refrigerator required for HTS equipment, there is a Brayton cycle refrigerator (Brayton Cycle Refrigerator) in addition to a GM refrigerator and a Stirling refrigerator.
For example, as disclosed in Patent Document 1, a Brayton cycle refrigerator using neon gas as a refrigerant gas (working fluid, working fluid) and liquid nitrogen as a cooling liquid has been developed. The liquid nitrogen is cooled to the subcooled state by exchanging heat between the neon gas circulating in the Brayton cycle refrigerator and the liquid nitrogen circulating in the liquid nitrogen circulation device in the auxiliary heat exchanger.

  Moreover, in order to make liquid nitrogen into a subcooling state efficiently with a liquid nitrogen circulation apparatus, it is better to use a plate fin heat exchanger as an auxiliary heat exchanger. A plate fin heat exchanger can be downsized.

JP 2011-106755 A

  However, when the neon gas that is the refrigerant of the Brayton cycle refrigerator becomes lower than the freezing point (63K) of the liquid nitrogen that is the cooling liquid, the liquid nitrogen is solidified in the sub heat exchanger, and the liquid nitrogen in the sub heat exchanger is There was a problem of blocking the flow path.

  In the liquid nitrogen circulation device, before cooling the HTS device as the object to be cooled, a heating means (for example, a heater or the like) is provided so that the liquid nitrogen channel is not frozen, so that the liquid nitrogen temperature is higher than the freezing point. It can also be controlled. However, a problem that requires extra equipment such as a heater occurs. In the first place, the need for extra equipment such as a heater means that liquid nitrogen is cooled too much, that is, the Brayton cycle refrigerator cannot be operated efficiently.

  Furthermore, when the state where liquid nitrogen solidifies in this way occurs, the operation change of the Brayton cycle refrigerator cannot be appropriately executed in response to a sudden change in the operating state of the HTS device, As a result, there is a problem that the liquid nitrogen temperature for cooling the HTS device to a constant temperature cannot be maintained at an appropriate temperature.

  The present invention has been made to solve such a problem, and can be brought into a subcooling state without solidifying the cooling liquid, and even when the operating state of the object to be cooled changes suddenly. It is an object of the present invention to provide a cooling apparatus for a high-temperature superconducting device capable of maintaining a coolant at an appropriate temperature and an operation method thereof.

To solve this problem,
A first aspect of the present invention includes a turbo compressor that compresses and circulates refrigerant gas;
A main heat exchanger that cools the compressed refrigerant gas by heat exchange with the returned refrigerant gas (refrigerant gas before compression);
An expansion turbine for adiabatically expanding the cooled refrigerant gas;
A sub heat exchanger for exchanging heat between the cryogenic refrigerant gas exiting the expansion turbine and the coolant;
A circulation pump for circulating the cooling liquid between the auxiliary heat exchanger and a body to be cooled;
Temperature measuring means for measuring the temperature of the coolant;
A first closed flow path constituting a circulation path for circulating the refrigerant gas after heat exchange in the auxiliary heat exchanger to the turbo compressor via the main heat exchanger;
A second closed flow path that constitutes a circulation path for circulating the coolant after the heat exchange with the auxiliary heat exchanger with the circulation pump;
The auxiliary heat exchanger is
A first heat exchanging unit having a path through which the refrigerant gas flows in parallel, and wherein the refrigerant gas exchanges heat with each other;
There is provided a cooling device for a high-temperature superconducting device, comprising: a second heat exchanging portion that exchanges heat so that the refrigerant gas heat-exchanged in the first heat exchanging portion and the cooling liquid face each other.

  Moreover, in the 1st aspect of this invention, it is preferable that the said temperature measurement means measures the temperature of the said cooling liquid after heat-exchanged with the said auxiliary heat exchanger.

  Further, in the first aspect of the present invention, the refrigerant gas is neon gas, a mixed gas of helium gas and neon gas, a mixed gas of hydrogen and neon gas, a mixed gas of hydrogen and helium gas, or neon gas, helium gas or the above-mentioned It is preferably one of mixed gases obtained by mixing an inert gas with a mixed gas.

  Moreover, in the 1st aspect of this invention, it is preferable that the said cooling liquid is liquid nitrogen.

The second aspect of the present invention is a method of operating the cooling device for the high-temperature superconducting equipment according to the first aspect of the present invention,
Provided is a method of operating a cooling device for a high-temperature superconducting device, in which the temperature of refrigerant gas is controlled by the number of revolutions of a turbo compressor so that the coolant in the second closed flow path is in a temperature range in which the coolant is in a subcooled state.

  In the second aspect of the present invention, it is preferable to reduce the rotational speed of the turbo compressor when the temperature of the coolant in the second closed flow path becomes low.

In the second aspect of the present invention, it is preferable to increase the rotational speed of the turbo compressor when the temperature of the coolant in the second closed flow path becomes high.
Further, in the second aspect of the present invention, the circulating flow rate of the cooling liquid is controlled by the number of rotations of the circulating pump so that the cooling liquid in the second closed flow path is in a temperature range where the cooling liquid enters a subcooled state. The rotation speed of the circulation pump is preferably controlled by inverter control.

  According to the cooling apparatus for high-temperature superconducting equipment of the present invention, a sub heat exchanger is provided in the cooling apparatus for bringing the coolant in the second closed flow path into a subcooled state, and the second heat exchanger in the sub heat exchanger is provided. Since the refrigerant gas in the first closed flow path is heat-exchanged by itself in the first heat exchange section and the coolant in the second closed flow path is cooled in the second heat exchange section, the sub heat exchanger The cooling liquid is not solidified inside.

  Further, according to the operation method of the cooling device for the high-temperature superconducting equipment of the present invention, the turbo compressor provided in the first closed flow path only in accordance with the temperature change of the coolant on the outlet side of the auxiliary heat exchanger. Since the number of rotations is controlled, the object to be cooled can be appropriately and efficiently cooled without solidifying the coolant in the sub heat exchanger even when there is a sudden change in the operating state of the object to be cooled. .

It is a systematic diagram showing a cooling device for high-temperature superconducting equipment according to an embodiment of the present invention. It is an expansion system diagram which shows the sub heat exchanger used for the cooling device of the high temperature superconducting apparatus which is one Embodiment of this invention. It is a graph showing the relationship between the refrigerating capacity of the Brayton cycle refrigerator to which the present invention is applied and the liquid nitrogen temperature at the sub heat exchanger outlet.

  Hereinafter, a refrigerator that is an embodiment to which a cooling device for high-temperature superconducting equipment according to the present invention is applied will be described in detail with reference to the drawings together with its operation method. In addition, in the drawings used in the following description, in order to make the characteristics easy to understand, there are cases where the characteristic features are enlarged for convenience, and the dimensional ratios of the respective components are the same as those of the actual device. Not necessarily. Further, in the present invention, “refrigerator” and “cooling device” mean the same content, and are given the same reference numeral 1.

First, the structure of the refrigerator of this embodiment is demonstrated.
As shown in FIG. 1, the combination of the refrigerator 1 and the body 6 to be cooled according to the present embodiment is a first circulation in which a turbo compressor 2, a main heat exchanger 3, an expansion turbine 4, and a sub heat exchanger 5 are provided. A path (first closed flow path) L1, a second circulation path (second closed flow path) L2 provided with the auxiliary heat exchanger 5, the cooled object 6, the circulation pump 7, and the temperature measuring means 10, and The refrigerant gas circulating in the first circulation path L1 and the coolant circulating in the second circulation path L2 exchange heat with the auxiliary heat exchanger 5.

  More specifically, the refrigerator 1 includes a turbo compressor 2, a main heat exchanger 3, an expansion turbine 4, an auxiliary heat exchanger 5, a temperature measuring means 10, and a circulation pump 7. It is only the to-be-cooled body 6 provided outside 1. Moreover, all the components of the refrigerator 1 other than the cooled object 6 are accommodated in the same vacuum container (cold box).

  Further, as shown in FIG. 1, the refrigerator 1 of the present embodiment adiabatically compresses a refrigerant gas such as neon gas with a turbo compressor 2, and the main heat exchanger 3 returns a high-pressure side refrigerant gas and a low-pressure side return gas. The refrigerant gas on the high pressure side is cooled by heat exchange with the refrigerant gas, and the cooled refrigerant gas adiabatically expands in the expansion turbine 4, so that the refrigerant gas itself becomes a very low temperature, and the auxiliary heat exchanger 5 The coolant is cooled by exchanging heat between the low-temperature refrigerant gas and the coolant such as liquid nitrogen sent from the circulation pump 7, and the cooled object 6 such as an HTS device is cooled with this coolant. .

As the refrigerant gas, helium, neon or hydrogen having a lower boiling point than nitrogen and a mixed gas thereof, or a mixed gas in which an inert gas such as nitrogen or argon is slightly mixed with these gases can be used.
The coolant is not particularly limited, but for example, liquid nitrogen can be used.

  The first circulation path L1 includes a turbo compressor 2 that compresses and circulates the refrigerant gas, a main heat exchanger 3 that cools the adiabatic-compressed refrigerant gas by heat exchange with the returned refrigerant gas, and the cooled refrigerant gas. Is a circulation path that circulates to the turbo compressor 2 through an expansion turbine 4 that adiabatically expands and an auxiliary heat exchanger that exchanges heat between the cryogenic refrigerant gas derived from the expansion turbine 4 and the coolant.

  The turbo compressor 2 is provided in the first circulation path L1 in order to adiabatically compress and circulate the refrigerant gas. In the present embodiment, a single-stage turbo compressor is illustrated, but the present invention is not limited to this. In addition, a two-stage turbo compressor including an intercooler or the like may be used.

  The turbo compressor 2 may be driven by an inverter. When the turbo compressor is driven by an inverter, when the outlet side pressure of the turbo compressor 2 becomes higher than a predetermined value, the output frequency of the inverter is changed to reduce the rotational speed of the turbo compressor 2. be able to. Therefore, the outlet side pressure of the turbo compressor 2 can be kept below a predetermined value. Thus, if the turbo compressor 2 can perform inverter control, the number of revolutions can be suitably controlled. In addition, if the rotation speed of the turbo compressor 2 is increased by changing the output frequency of the inverter, the outlet side pressure of the turbo compressor 2 can be increased.

  Further, a heat exchanger may be provided in the rear stage on the outlet side of the turbo compressor 2. With this heat exchanger, the high-temperature refrigerant gas emitted from the turbo compressor 2 can be cooled to near atmospheric temperature. An example is a water-cooled aftercooler.

  As shown in FIG. 1, the main heat exchanger 3 is installed between the turbo compressor 2 and the expansion turbine 4 in the first circulation path L1, and the refrigerant gas adiabatically compressed by the turbo compressor 2 and The refrigerant gas discharged from the turbo compressor 2 is cooled by exchanging heat with the refrigerant gas returned from the auxiliary heat exchanger 5.

As shown in FIG. 1, the expansion turbine 4 is installed at the rear stage of the main heat exchanger 3 in the first circulation path L1, and a refrigerant gas cooled by the main heat exchanger 3 is adiabatically expanded to generate a cryogenic temperature. Refrigerant gas. Further, the expansion turbine 4 may be integrated with the turbo compressor 2 so as to be provided coaxially. Since the power for operating the expansion turbine 4 and the turbo compressor 2 can be integrated by adopting an integral structure, the refrigerator can be miniaturized.
Note that the outlet temperature of the expansion turbine 4 (corresponding to the temperature at point 1 in FIG. 2) depends on the type of refrigerant gas, but in the cooling device of the present invention in which a main heat exchanger and a sub heat exchanger are combined, Often within the range of 55K to 65K.

  As shown in FIG. 1, the auxiliary heat exchanger 5 is installed on the outlet side of the expansion turbine 4 in the first circulation path L <b> 1, and cools the refrigerant gas and the object 6 to be cooled that have been extremely cooled by the expansion turbine 4. The cooling liquid is cooled by exchanging heat with the cooling liquid. That is, the object to be cooled is cooled by the coolant gas cooling the coolant.

As shown in FIG. 1, the circulation pump 7 circulates the coolant in the second circulation path L2.
As shown in FIG. 1, the second circulation path L <b> 2 is provided with a temperature measuring means 10 for measuring the temperature of the coolant flowing out from the sub heat exchanger 5. Examples of the temperature measuring means 10 include a thermocouple.
Moreover, as the to-be-cooled body 6, HTS apparatus, such as a superconducting power transmission cable, a superconducting transformer, a superconducting motor, is mentioned, for example.

Next, the operation method of the refrigerator 1 of this embodiment is demonstrated.
First, the refrigerant gas is adiabatically compressed by the turbo compressor 2 in the first circulation path L1. Next, the refrigerant gas is introduced into the main heat exchanger 3 and heat exchanged with the refrigerant gas returned from the auxiliary heat exchanger 5 (the refrigerant gas before being adiabatically compressed). At this time, the adiabatic-compressed refrigerant gas is cooled to 65 to 70K.
Since the refrigerant gas adiabatically compressed by the turbo compressor 2 becomes a high temperature, a heat exchanger may be provided at the subsequent stage of the turbo compressor 2 to cool the refrigerant gas to near the atmospheric temperature.

  Next, in the expansion turbine 4, adiabatic expansion from the pressure (high pressure side pressure, 1-2 MPa) for introducing the refrigerant gas to the expansion turbine 4 to the pressure (low pressure side pressure, 0.5-1 MPa) derived from the expansion turbine 4 is performed. And the temperature of the refrigerant gas is lowered to 55 to 65K.

  Next, the refrigerant gas cooled to 55 to 65 K by the expansion turbine 4 is introduced into the auxiliary heat exchanger 5 and heat exchanged with the coolant that cools the cooled object 6. At this time, the coolant is cooled to the subcooled state. For example, when liquid nitrogen is cooled to 65K, the refrigerant gas temperature rises to about 65 to 70K.

  On the other hand, the coolant in the subcooled state circulates through the second circulation path L2 so that the cooled body 6 is maintained at a constant temperature by the circulation pump 7. For example, in the case of liquid nitrogen under atmospheric pressure, the temperature range of the coolant in the subcooled state is a temperature from the boiling point (about 77 K) to the freezing point (about 63 K). In addition, the temperature of the coolant for cooling the cooled object 6 is constantly monitored by the temperature measuring means 10. Although the temperature at which the object to be cooled 6 is held varies slightly depending on the HTS equipment, most of them are cooled and maintained at about 70K.

  Next, the refrigerant gas derived from the auxiliary heat exchanger 5 (returned refrigerant gas) returns to the main heat exchanger 3 and is heat-exchanged with the refrigerant gas adiabatically compressed by the turbo compressor 2. At this time, the temperature of the refrigerant gas (returned refrigerant gas) derived from the auxiliary heat exchanger 5 further increases to near the atmospheric temperature. Thereafter, the refrigerant gas (returned refrigerant gas) derived from the auxiliary heat exchanger 5 returns to the inlet side of the turbo compressor.

As described above, the first circulation path L1 provided in the refrigerator 1 of the present embodiment is configured such that the refrigerant gas circulates, and constitutes a Brayton cycle.
Further, when the pressure loss of the cooling gas is large in the auxiliary heat exchanger 5, the expansion turbine 4 is provided in the rear stage of the auxiliary heat exchanger 5, that is, in the front stage of the main heat exchanger 3, in the first circulation path L1, A high-pressure refrigerant gas of 2 MPa can be introduced into the auxiliary heat exchanger 5. Thereby, even if the pressure loss of the cooling gas is large in the auxiliary heat exchanger 5, it can be dealt with.

Next, the sub heat exchanger 5 of the present embodiment will be described in more detail based on FIG.
As shown in FIG. 2, in the auxiliary heat exchanger 5, the first circulation path L1 through which the refrigerant gas flows is arranged so that the path L1a and the path L1b are in parallel (the refrigerant gas in the path L1a and the path L1b The first heat exchange section 5a is formed so that the refrigerant gas is in a parallel flow. Further, in the auxiliary heat exchanger 5, the second heat exchange is performed so that the path L2a through which the coolant flows is opposed to the path L1b through which the refrigerant gas flows (so that the path L1b and the path L2a are opposed to each other). Part 5b is formed.

By providing such a flow path in the sub heat exchanger 5, the temperature of the refrigerant gas cooled by the expansion turbine 4 is exchanged between the refrigerant gases in the parallel flow portion of the first heat exchange section 5a. In the counterflow portion of the second heat exchanging portion 5b, heat is exchanged between the refrigerant gas and the cooling liquid (subcooled state) for cooling the cooled object 6 to cool the cooling liquid. To do.
That is, in the sub heat exchanger 5, the refrigerant gas and the cooling liquid are heat-exchanged in a state where the cooling liquid is in the subcooled state and the freezing point or higher.

By the way, as shown in FIG. 1, the temperature of the coolant changes due to the load fluctuation / operation change of the cooled object (HTS device) 6. On the other hand, according to the refrigerator 1 of the present embodiment, the temperature measuring means 10 is provided in the subsequent stage of the auxiliary heat exchanger 5 (that is, the preceding stage of the cooled object 6), so that the cooled object 6 is cooled. The temperature of the coolant to be measured can always be measured. Further, the rotational speed of the turbo compressor 2 can be controlled in accordance with the measured temperature of the coolant. When the measured temperature of the coolant is lowered, that is, when the load on the cooled object 6 such as an HTS device is reduced, the rotational speed of the turbo compressor 2 is lowered. On the other hand, when the measured temperature of the coolant rises, that is, when the load on the cooled object 6 such as an HTS device increases, the rotational speed of the turbo compressor 2 is increased.
As described above, the refrigeration capacity of the refrigerator 1 can be changed by controlling the rotational speed of the turbo compressor 2.

  The expansion ratio of the expansion turbine 4 is determined by the relationship between the high pressure side pressure and the low pressure side pressure of the refrigerator 1. It is the compression ratio of the turbo compressor 2 that determines these pressures in the refrigerator 1. The expansion turbine 4 only has a function of expanding the refrigerant gas outlet pressure (high pressure side pressure) increased through the turbo compressor 2 to the refrigerant gas inlet pressure (low pressure side pressure) of the turbo compressor 2. Thus, the expansion ratio cannot be determined by the expansion turbine 4 itself. That is, the expansion ratio of the refrigerant gas in the expansion turbine 4 is determined according to the compression ratio of the refrigerant gas in the turbo compressor 2.

That is, when the rotational speed of the turbo compressor 2 is lowered, the compression ratio becomes small due to the characteristics of the turbo compressor 2 and, as a result, the expansion ratio of the expansion turbine 4 becomes small. Therefore, the refrigerant gas temperature derived from the expansion turbine 4 becomes It rises more than before the rotation speed is lowered.
On the contrary, when the rotational speed of the turbo compressor 2 is increased, the compression ratio increases due to the characteristics of the turbo compressor 2, and as a result, the expansion ratio of the expansion turbine 4 increases, so that the refrigerant gas temperature derived from the expansion turbine 4 Falls below before increasing the number of revolutions.

  As described above, according to the refrigerator 1 of the present embodiment, the refrigerant gas can be quickly controlled by controlling the rotation speed of the turbo compressor 2 in accordance with the load fluctuation / operation change of the cooled object 6 such as an HTS device. Can be maintained at an appropriate temperature. Therefore, the to-be-cooled body 6 can be kept at a constant temperature.

  As described above, the refrigerator 1 of the present embodiment is a sub heat exchanger for bringing the coolant (liquid nitrogen) in the second circulation path L2 into a subcool state in the refrigerator 1 constituting the Brayton cycle. 5, the refrigerant gas (neon gas) in the first circulation path L1 is heat-exchanged by the first heat exchange section 5a in the sub heat exchanger 5 and the second circulation path L2 in the second heat exchange section 5b. It is comprised so that the inside coolant may be cooled. Therefore, the cooling liquid is not solidified in the auxiliary heat exchanger 5.

  In addition, according to the operation method of the refrigerator 1 of the present embodiment, the rotation of the turbo compressor 2 provided in the first circulation path L1 according to only the temperature change of the coolant on the outlet side of the auxiliary heat exchanger 5. Because the number is controlled, the high-temperature superconductor in the HTS device is not solidified in the sub heat exchanger 5 even if there is a sudden change in the operating state of the cooled object (HTS device) 6. It can be cooled appropriately and efficiently.

(Control of the rotation speed of the circulation pump 7)
In the cooling apparatus for high-temperature superconducting equipment according to the present invention, the rotational speed of the turbo compressor 2 is controlled so that the temperature 10 at the coolant outlet (point 4) of the auxiliary heat exchanger 5 is constant. Therefore, if the circulating flow rate of the coolant is constant, the temperature of the coolant inlet (point 3) of the auxiliary heat exchanger 5 depends on the load of the body 6 to be cooled.
When the load on the cooled object 6 decreases, the temperature of the coolant inlet (point 3) of the auxiliary heat exchanger 5 decreases, and the temperature of the refrigerant gas that returns to the main heat exchanger 3 also decreases. Furthermore, the inlet temperature of the expansion turbine 4 also decreases. On the other hand, when the load on the cooled object 6 decreases, automatic control is performed to reduce the rotational speed of the turbo compressor 2 in order to reduce the refrigerating capacity. When the rotational speed of the turbo compressor 2 decreases, the compression ratio of the refrigerant gas decreases with the flow rate. At this time, a decrease in the inlet temperature of the expansion turbine 4 and a decrease in the expansion ratio occur simultaneously. However, the outlet temperature of the expansion turbine may increase or decrease depending on the characteristics of the turbo compressor 2 and the expansion turbine 4 used.
When the outlet temperature of the expansion turbine 4 rises, the temperature of the refrigerant gas inlet (point 1) of the auxiliary heat exchanger 5 rises, so that the liquid nitrogen (coolant) is solidified in the auxiliary heat exchanger 5. Absent. On the other hand, when the outlet temperature of the expansion turbine 4 is lowered, the temperature of the refrigerant gas inlet (point 1) of the sub heat exchanger 5 is lowered, and there is a risk that the coolant is solidified in the sub heat exchanger 5. In order to avoid the solidification of the cooling liquid, it is preferable to reduce the circulation flow rate of the cooling liquid by reducing the rotational speed of the circulation pump 7 based on the temperature of the refrigerant gas inlet (point 1) of the sub heat exchanger 5. When the circulating flow rate of the cooling liquid decreases, the temperature of the cooling liquid rises due to the influence of the body 6 to be cooled. As a result, the refrigerant gas whose temperature has decreased in the sub heat exchanger 5 and the cooling gas whose temperature has increased perform heat exchange, so that the cooling liquid in the sub heat exchanger 5 can be prevented from solidifying.
When the load of the cooled object 6 rises and returns to a steady state, the circulating flow rate of the coolant is restored by immediately increasing the rotational speed of the turbo compressor 2 and the rotational speed of the circulation pump 7 to the original values. Let Thereby, it is possible to maintain the temperature of the coolant in the second closed flow path L2 so as to be in a temperature range where the subcooled state is achieved, and to maintain the temperature of the entire system stably. General inverter control can be applied to the rotational speed control of the circulation pump 7.

  Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.

(Example 1)
The refrigerator to which the cooling device for the high-temperature superconducting equipment of the present invention shown in FIG. 1 was applied was operated until it reached a steady state. Neon gas was used as the refrigerant gas, and liquid nitrogen was used as the coolant. The results of measuring the temperature at each point (measurement point) shown in FIG.

  As shown in Table 1 above, the temperature at point 1a shown in FIG. 2 was 64.8K, the temperature at point 1c was 65.4K, and the temperature at point 4 was 67.0K. Here, the nitrogen temperature in the subcooled state under atmospheric pressure is from the boiling point (about 77 K) to the freezing point (about 63 K). Therefore, according to the refrigerator of the present invention, the refrigerant gas temperature can be maintained at a temperature at which the coolant does not solidify without using a heater or the like for heating the coolant.

(Example 2)
The Brayton cycle refrigerator to which the cooling apparatus for high-temperature superconducting equipment of the present invention shown in FIG. Neon gas was used as the refrigerant gas, and liquid nitrogen was used as the coolant.
As a result of controlling the rotation speed of the turbo compressor and controlling the refrigerating capacity of the refrigerator by changing the load of the HTS equipment, the load of the HTS equipment fluctuates from 0.7 to 2.5 kW as shown in FIG. Even in this case, the temperature of the liquid nitrogen outlet (point 4) of the auxiliary heat exchanger was constant at 67K. Therefore, according to the cooling device for high-temperature superconducting equipment of the present invention, the refrigerant gas temperature is maintained at a temperature at which the cooling liquid does not solidify without using a heater or the like for heating the cooling liquid even in the case of load fluctuation operation. We were able to.

1 Refrigerator (cooling device)
DESCRIPTION OF SYMBOLS 2 Turbo compressor 3 Main heat exchanger 4 Expansion turbine 5 Sub heat exchanger 5a 1st heat exchange part 5b 2nd heat exchange part 6 To-be-cooled body 7 Circulation pump 10 Temperature measurement means L1 1st circulation path (1st closing) Flow path)
L2 Second circulation path (second closed flow path)

Claims (8)

A turbo compressor that compresses and circulates refrigerant gas;
A main heat exchanger that cools the compressed refrigerant gas by heat exchange with the returned refrigerant gas;
An expansion turbine for adiabatically expanding the cooled refrigerant gas;
A sub heat exchanger for exchanging heat between the cryogenic refrigerant gas exiting the expansion turbine and the coolant;
A circulation pump for circulating the cooling liquid between the auxiliary heat exchanger and a body to be cooled;
Temperature measuring means for measuring the temperature of the coolant;
A first closed flow path constituting a circulation path for circulating the refrigerant gas after heat exchange in the auxiliary heat exchanger to the turbo compressor via the main heat exchanger;
A second closed flow path that constitutes a circulation path for circulating the coolant after the heat exchange with the auxiliary heat exchanger with the circulation pump;
The auxiliary heat exchanger is
A first heat exchanging unit having a path through which the refrigerant gas flows in parallel, and wherein the refrigerant gas exchanges heat with each other;
A cooling apparatus for a high-temperature superconducting device, comprising: a second heat exchange unit that exchanges heat so that the refrigerant gas exchanged in the first heat exchange unit and the cooling liquid face each other.   2. The cooling device for a high-temperature superconducting device according to claim 1, wherein the temperature measuring unit measures a temperature of the coolant after heat exchange is performed by the sub heat exchanger.   The refrigerant gas is neon gas, a mixed gas of helium gas and neon gas, a mixed gas of hydrogen and neon gas, a mixed gas of hydrogen and helium gas, or a mixed gas of an inert gas mixed with neon gas, helium gas or the mixed gas. The cooling device for high-temperature superconducting equipment according to claim 1, which is any one of them.   The cooling device for high-temperature superconducting equipment according to claim 1, wherein the cooling liquid is liquid nitrogen. A method for operating a cooling device for a high-temperature superconducting device according to any one of claims 1 to 4,
A method of operating a cooling device for a high-temperature superconducting device, wherein the temperature of the refrigerant gas is controlled by the number of revolutions of the turbo compressor so that the temperature of the coolant in the second closed flow path is in a temperature range that is in a subcooled state.   The method for operating a cooling device for a high-temperature superconducting device according to claim 5, wherein when the temperature of the coolant in the second closed flow path becomes low, the rotational speed of the turbo compressor is lowered.   The method of operating a cooling device for a high-temperature superconducting device according to claim 5, wherein when the temperature of the coolant in the second closed flow path becomes high, the number of revolutions of the turbo compressor is increased. Controlling the circulation flow rate of the coolant by the number of rotations of the circulation pump so that the coolant in the second closed flow path is in a temperature range in which the coolant is in a subcooled state.
The operating method of the cooling device for a high-temperature superconducting device according to claim 5, wherein the rotational speed of the circulation pump is controlled by inverter control.

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