KR102340760B1 - Decompression type cooling system for Superconducting cable - Google Patents

Abstract

The present invention relates to a pressure-sensitive cooling system for a superconducting cable, wherein the pressure-sensitive cooling system for a superconducting cable according to the present invention includes a core part provided with a superconducting conductor layer, and a cooling part for cooling the core part with a liquid first refrigerant on the outside of the core part In the pressure-sensitive cooling system for a superconducting cable comprising: a heat insulating unit provided outside the cooling unit; and a vacuum unit provided outside the heat insulating unit; provided along a refrigerant circulation path connected to the cooling unit of the superconducting cable A circulation pump for circulating the first liquid refrigerant through the refrigerant circulation passage, a refrigerant tank for supplying the liquid first refrigerant to the refrigerant circulation passage, and the refrigerant circulation passage using the vaporization heat of the second refrigerant A pressure reduction type cooling container for cooling the liquid first refrigerant, a vacuum pump for discharging the gaseous second refrigerant generated in the reduced pressure cooling container, and the relatively high temperature gaseous second refrigerant discharged from the vacuum pump, and in the reduced pressure cooling container It characterized in that it comprises a heat exchange unit for performing heat exchange with the relatively low-temperature gas-phase second refrigerant supplied to the vacuum pump.

Description

{Decompression type cooling system for Superconducting cable}

The present invention relates to a pressure-sensitive cooling system for a superconducting cable.

Superconducting wire has a large power transmission ability even at low voltage because electrical resistance converges to near zero at a constant temperature. A superconducting cable having such a superconducting wire uses a method of cooling using a refrigerant such as nitrogen to form and maintain a cryogenic environment and/or a method of thermal insulation of forming a vacuum layer.

In the superconducting cable, in order to maintain a cryogenic environment, a cooling system for stably cooling the refrigerant of the superconducting cable is required, which has a low probability of failure and minimizes power consumption.

Republic of Korea Patent Publication No. 10-2011-0060636 (published on June 08, 2011)

An object of the present invention is to provide a cooling system capable of preventing a cryogenic refrigerant from flowing into a vacuum pump constituting the cooling system in a reduced pressure cooling system for cooling the refrigerant of a superconducting cable. In particular, an object of the present invention is to provide a cooling system that does not require additional components and can prevent a cryogenic refrigerant from flowing into the vacuum pump by a simple structure.

In order to solve the above problems, the present invention includes a core part provided with a superconducting conductor layer, a cooling part for cooling the core part with a liquid first refrigerant on the outside of the core part, a heat insulating part provided on the outside of the cooling part, In the pressure reduction type cooling system of a superconducting cable including a vacuum unit provided outside the heat insulating part, it is provided along a refrigerant circulation passage connected to the cooling unit of the superconducting cable and circulates the liquid first refrigerant through the refrigerant circulation passage a circulating pump, a refrigerant tank for supplying the first liquid refrigerant to the refrigerant circulation passage, a reduced pressure cooling container provided along the refrigerant circulation passage to cool the liquid first refrigerant by using the vaporization heat of a second refrigerant, the pressure reduction type A vacuum pump for discharging the second gaseous refrigerant generated in the cooling container, the relatively high-temperature second gas-phase refrigerant discharged from the vacuum pump, and the relatively low-temperature second gas-phase supplied from the reduced-pressure cooling container to the vacuum pump It is possible to provide a pressure-sensitive cooling system for a superconducting cable, characterized in that it comprises a; heat exchange unit for performing heat exchange of the refrigerant.

In addition, the heat exchange unit includes a connection passage connecting the pressure-sensitive cooling vessel and the vacuum pump, and the gaseous second refrigerant discharged from the vacuum pump flows along the inside, and is provided adjacent to the connection passage by a predetermined overlapping length An exhaust passage may be provided.

In this case, the heat exchange unit may have a double pipe structure in which the discharge passage surrounds the connection passage.

In addition, a flow direction of the second gaseous refrigerant flowing along the connection flow path and a flow direction of the gaseous second refrigerant flowing along the discharge flow path may be configured to be opposite to each other.

In addition, the overlapping length may be determined such that the temperature of the second gaseous refrigerant flowing into the vacuum pump through the connection passage has a range of 278K to 288K.

Here, a vaporizer for heat exchange between the gaseous second refrigerant and the external atmosphere may be further provided on the connection passage.

Also, the first refrigerant and the second refrigerant may be of the same type.

In this case, the refrigerant circulation passage may be connected to the cooling unit of the superconducting cable through a terminal junction box connected to the superconducting cable.

According to the pressure-sensitive cooling system of the superconducting cable according to the present invention, it is possible to prevent the inflow of cryogenic refrigerant into the vacuum pump constituting the cooling system without requiring additional components, thereby preventing malfunction or malfunction of the vacuum pump can do.

In addition, in the present invention, since the refrigerant gas flowing into the vacuum pump is heated by using the waste heat of the refrigerant gas exhausted from the vacuum pump, it is efficiently introduced into the vacuum pump without using external power like a separate heater. It is possible to increase the temperature of the refrigerant gas.

1 shows a step-by-step stripped perspective view of a superconducting cable according to the present invention.
FIG. 2 shows a cross-sectional view of the superconducting cable shown in FIG. 1 .
3 shows another embodiment of a superconducting cable according to the present invention.
4 is a cross-sectional view illustrating a state in which the superconducting cable shown in FIG. 3 is installed in a horizontal direction.
5 shows a schematic diagram of a pressure-sensitive cooling system according to an embodiment of the prior art.
6 shows a schematic diagram of a reduced pressure cooling system according to another embodiment.
7 is a perspective view illustrating a double pipe structure of a heat exchange unit.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed subject matter may be thorough and complete, and the spirit of the present invention may be sufficiently conveyed to those skilled in the art. Like reference numerals refer to like elements throughout.

Figure 1 shows a perspective view stripped step by step of the superconducting cable according to the present invention, Figure 2 shows a cross-sectional view of the superconducting cable shown in 1.

The basic structure of the superconducting cable according to the present invention will be described.

The superconducting cable shown in FIG. 1 includes at least one superconducting conductor layer 130 including a former 110 and a plurality of superconducting wires arranged side by side in the longitudinal direction of the former 110 to surround the outside of the former 110 . ), an insulating tape 140 surrounding the superconducting conductor layer 130 , and a plurality of superconducting wires arranged side by side in the longitudinal direction of the former 110 so as to surround the outside of the insulating tape 140 . The core part 100 including the superconducting shielding layer 180 of more than one layer is provided outside the core part 100 to cool the core part 100 , and a liquid phase for cooling the core part 100 . The cooling unit 200 having a refrigerant flow path of the first refrigerant, the inner metal tube 300 provided outside the cooling unit 200, the inner metal tube 300 are provided outside the inner metal tube 300, and the heat insulating material 401 is divided into several layers. A vacuum unit 500 having a plurality of spacers 560 at spaced apart positions outside the insulating unit 400 in order to vacuum insulate the insulating unit 400 forming the wound insulating layer and the cooling unit 200 . , may include an external metal tube 600 provided outside the vacuum unit 500 , and an external jacket 700 provided outside the external metal tube 600 to form a sheath layer.

Each component constituting the superconducting cable is reviewed sequentially as follows. The former 110 provides a place for mounting a flat and long superconducting wire around the former 110 and at the same time serves as a frame for forming a shape, and may be a path through which a fault current flows. The former 110 may have a shape in which a plurality of copper (Cu) conductor wires 111 having a circular cross-section are compressed into a circular shape.

Specifically, basically the former 110 has a round cylindrical shape, and serves as a frame for placing a flat and long superconducting wire. The diameter of the former 110 is determined to be as close to a circular structure as possible when the superconducting wires are placed on the former 110 without lifting the superconducting wires in consideration of the width of the superconducting wires.

As shown in FIGS. 1 and 2, the former may be configured in a form with a full center, but the former 110 is formed in a hollow pipe shape to serve as a frame for raising the superconducting wire, and a refrigerant inside It may be configured to serve as a path for movement, and each of the conductor wires 111 constituting the former may be made of copper or the like, and by connecting each wire with each superconducting wire in parallel, power in the power system It can also be configured to act as a return conductor in the event of a fault current caused by a short circuit in the system (eg, lightning strike, insulation breakdown, etc.).

The cross-sectional area of a conductor such as copper constituting the wire may be determined according to the capacity of the fault current, and in the case of high voltage, the copper wire may be compressed into a circular shape to form a stranded wire.

When a fault current occurs in the power system, the role of the return conductor is attached to each superconducting wire as described later in addition to the former composed of the conductor element wire 111, and there is a conductive layer made of a metal material that is conductive at room temperature. The conductive layer may be in the form of a metal tape.

For example, in order to reinforce the mechanical rigidity of the superconducting wire constituting the superconducting cable according to the present invention, conductive layers made of a metal material having conductivity at room temperature are provided on both surfaces of the superconducting wire. Such a conductive layer may prevent breakage due to torsional stress during winding of the superconducting wire by reinforcing mechanical rigidity.

Such a conducting layer reinforces the mechanical rigidity of the superconducting wire and at the same time can perform the role of the return of the fault current together with the former when an accident such as a short circuit occurs. It may have a diameter smaller than the diameter of the former constituting the .

Since the conductor element wires 111 having a circular cross-section of several strands constituting the former 110 are compressed into a circular shape, the surface of the former 110 is inevitably convex and convex. Accordingly, the smoothing layer 120 may be coated on the outside of the former 110 in order to smooth the convex and convex surface of the former 110 . The smoothing layer 120 may be made of a material such as semi-conductive carbon paper or brass tape.

Although not shown in the drawings, a cushion layer may be further provided between the smoothing layer 120 and the superconducting conductor layer 130 . The cushion layer may be provided to protect the superconducting conductor layer by using a semiconducting carbon paper tape.

A first superconducting conductor layer 130a in which a layer is formed by being surrounded by a plurality of superconducting wires 131a may be provided outside the former 110 planarized by the smoothing layer 120 . The first superconducting conductor layer 130a may be installed such that a plurality of superconducting wires are adjacent to each other and surround the smooth layer 120 .

In addition, as shown in FIG. 1 , the superconducting conductor layer 130 may be configured in multiple layers depending on the capacity of the current to be transmitted or distributed through the superconducting cable.

In the embodiment shown in FIG. 1, it is shown that a total of two superconducting conductor layers 130a and 130b are provided. In addition, if the superconducting conductor layers are simply stacked and disposed, the current capacity is not increased according to the skin effect of the current. In order to prevent such a problem, when the superconducting conductor layer is provided in multiple layers, the insulating tape 140 may be provided between the superconducting conductor layers 130a and 130b. The insulating tape 140 may be disposed between the stacked superconducting conductor layers 130a and 130b to insulate the superconducting conductor layers 130a and 130b from each other to prevent a skin effect of the stacked superconducting wires. Conductive directions of the superconducting conductor layers stacked in multiple layers by the insulating tape 140 may coincide.

In the embodiment shown in Fig. 1, the superconducting layer 130 is an example composed of two layers of the first superconducting conductor layer 130a and the second superconducting conductor layer 130b, but if necessary, more layers of superconducting A conductive layer may be provided.

In addition, each of the superconducting wires 131a and 131b constituting the respective superconducting conductor layers 130a and 130b may be connected in parallel with the respective wires constituting the former 110 . This is to classify the fault current into the wires of the former 110 when the current flowing through the superconducting wire is short-circuited (tooth, lightning, insulation breakdown, breakdown of superconducting conditions, etc.). In this way, heat generation or damage to the superconducting wire can be prevented.

An inner semiconducting layer 150 may be provided outside the second superconducting conductor layer 130b provided outside the first superconducting conductor layer 130a. The inner semiconducting layer 150 may be provided to relieve electric field concentration for each region of the superconducting conductor layer 130 and to even out the surface electric field. Specifically, it may be provided to alleviate the concentration of an electric field generated at the edge portion of the superconducting wire and to make the electric field distribution even. This is also the same for the outer semiconducting layer 170, which will be described later.

The inner semiconducting layer 150 may be provided in a manner in which a semiconducting tape is wound.

An insulating layer 160 may be provided outside the inner semiconducting layer 150 . The insulating layer 160 may be provided to increase the dielectric strength of the superconducting cable. In general, XLPE (Cross Linking-Polyethylene) or oil filled cable is used for the insulation of high voltage cables, but superconducting cables are cooled to cryogenic temperatures for superconductivity of superconducting wires, and XLPE is broken at cryogenic temperatures to cause insulation breakdown. There is a problem, and since an oil filled cable may cause environmental problems, the superconducting cable according to the present invention may use general paper insulating paper as the insulating layer 160 , and the insulating layer 160 . Silver may be configured by winding the insulating paper a plurality of times.

The insulating paper is mainly kraft paper or PPLP (Polypropylene Laminated Paper). In the case of superconducting cables among various earth insulating materials, PPLP insulating paper is used in consideration of ease of winding and dielectric strength characteristics.

An external semiconducting layer 170 may be provided outside the insulating layer 160 . The outer semiconducting layer may also be provided to relieve electric field concentration by region of the superconducting conductor layer 130 and to even out the surface electric field, and the outer semiconducting layer 170 may also be provided in such a way that a semiconducting tape is wound. .

In addition, a superconducting shielding layer 180 may be provided outside the outer semiconducting layer 170 . The method of forming the superconducting shielding layer 180 may be the same as the method of forming the superconducting conductor layer 130 . When the surface of the outer semiconducting layer 170 is uneven, a smoothing layer (not shown) may be provided as needed. can be placed side by side.

The current flowing through the shielding layer made of the second-generation superconducting wire is designed to be about 95% of the current flowing through the superconducting layer, so that the leakage magnetic field can be minimized.

A core exterior layer 190 serving as an exterior of the core part 100 may be provided outside the superconducting shielding layer 180 . The core exterior layer 190 may include various tapes or binders, and serves to bind all components of the core part 100 to an exterior so that the core part 100 can be exposed to a cooling layer, which will be described later. and may be composed of a metal tape such as SUS material.

In this way, the core part 100 of the superconducting cable can be configured, and in FIGS. 1 and 2, the smooth layer and the semiconducting layer are shown to be composed of a single layer of the same material, but various auxiliary layers as needed. can be added.

A cooling unit 200 may be provided outside the core unit 100 . The cooling unit 200 may be provided to cool the superconducting wire rod of the core unit 100 , and the cooling unit 200 may have a flow path for the first liquid refrigerant therein. Liquid nitrogen may be used as the liquid first refrigerant, and the liquid refrigerant (liquid nitrogen) circulates through the cooling passage in a cooled state to have a temperature of approximately 70K and is provided in the core unit 100 inside the cooling unit It is possible to maintain the cryogenic temperature, which is the superconducting condition of the superconducting wire to be used.

The cooling passage provided in the cooling unit 200 may allow a liquid refrigerant to flow in one direction, and may be recovered from a junction box of a superconducting cable, etc., re-cooled, and then supplied to the cooling passage of the cooling unit 200 again. The cooling system of the refrigerant connected to the cooling unit 200 will be described in detail later.

An inner metal tube 300 may be provided outside the cooling unit 200 . The inner metal tube 300 serves as a sheath for the superconducting cable to prevent mechanical damage to the core part 100 during the installation and operation of the superconducting cable together with the outer metal tube 600 to be described later. The superconducting cable is wound on a drum for easy manufacturing and transport, and when installing, the cable wound on the drum is deployed and installed, so bending stress or tensile stress can be continuously applied to the superconducting cable.

In order to maintain the initial performance even in a situation where such mechanical stress is applied, the inner metal tube 300 may be provided. Accordingly, the inner metal tube 300 has a corrugated structure in which uplifts and depressions are repeated in the longitudinal direction of the superconducting cable to reinforce rigidity against mechanical stress, and the inner metal tube 300 is made of a material such as aluminum. can be

Since the inner metal tube 300 is provided outside the cooling unit 200, it may be a cryogenic temperature corresponding to the temperature of the liquid refrigerant. Accordingly, the inner metal tube 300 may be divided into a low-temperature part metal tube.

The heat insulating unit 400 may constitute a multi-layer insulation (MLI) and may be provided to prevent heat intrusion into the inner metal tube 300 from occurring.

In particular, since the inner metal tube 300 is made of a metal material, heat intrusion or heat exchange by conduction is easy, so that the heat insulating part 400 can minimize heat exchange or heat intrusion mainly by conduction, and a metal with high reflectance Due to the film material, the effect of preventing heat exchange or heat intrusion by radiation can also be obtained.

A vacuum part 500 may be provided outside the heat insulating part 400 . The vacuum unit 500 may be provided to minimize heat transfer due to convection or the like in the direction of the insulating layer, which may occur when the thermal insulation by the insulating unit 400 is insufficient.

The vacuum unit 500 may be formed by forming a separation space outside the heat insulating unit 400 and evacuating the separation space.

The vacuum unit 500 is a spaced space provided to prevent heat intrusion due to convection or the like from the outside at room temperature to the core part, and may include at least one spacer 560 to form a physical spaced space. In order to prevent contact with the external metal tube 600 provided on the outside of the spaced space in the vacuum part 500 and the heat insulating part 400 inside the vacuum part 500 over the entire area of the superconducting cable, the spaced space At least one spacer 560 may be provided therein, and specifically, it may be increased or decreased according to the type or size of the superconducting cable or spacer. Although the superconducting cable 1000 shown in FIGS. 1 and 2 is illustrated as having four spacers, the number may be increased or decreased.

The spacer 560 may be disposed along the longitudinal direction of the superconducting cable, and may be wound around the outside of the core part 100 , specifically, the heat insulating part 400 , in a spiral or circular shape.

The number of spacers 560 may include 3 to 5 spacers in the superconducting cable according to the present invention. The spacer may prevent heat exchange due to conduction by forming a separation space, and the spacer may have a single-layer or multi-layer structure.

The material of the spacer 560 may be a polyethylene (FEP, PFA, ETFE, PVC, P.E, PTFE) material.

In addition, if necessary, the spacer 560 may be made of a fluorinated polyethylene (PTFE, Poly Tetra Fluoro Ethylene) material, or may be made of a general resin or polyethylene material and the surface thereof may be coated with fluorinated polyethylene or the like. In this case, the fluorinated polyethylene may be Teflon.

Teflon is a kind of fluororesin, and Teflon forms a very stable compound due to the strong chemical bond between fluorine and carbon. have. In addition, since Teflon has a certain degree of flexibility, it spirally surrounds the heat insulating part 400, can be wound and disposed in the longitudinal direction of the superconducting cable, and has a certain level of strength so that the insulating part 400 and the outside It is used as a separation means for preventing the metal tube 600 from contacting, and may serve to physically maintain the separation space constituting the vacuum unit 500 . The spacer 560 may have a diameter of 4 millimeters (mm) to 8 millimeters (mm). The cross-sectional shape of the spacer 560 may be various shapes such as a circle, a triangle, a square, and a star.

An external metal tube 600 may be provided outside the vacuum unit 500 provided with the spacer 560 . The outer metal tube 600 may be made of the same shape and material as the inner metal tube 300 , and the outer metal tube 600 is configured to have a larger diameter than the inner metal tube 300 through a spacer 560 . It is possible to enable the formation of a separation space. A detailed description of the spacer 560 will be postponed.

In addition, an external jacket 700 performing an external function for protecting the inside of the superconducting cable may be provided on the outside of the external metal tube 600 . As the outer jacket, a sheath material constituting the outer jacket 700 of a conventional power cable may be used. The outer jacket 700 may prevent corrosion of the metal tube 600 and the like therein, and may prevent damage to the cable due to external force. It may be made of a material such as polyethylene (PE) or polyvinyl chloride (PVC).

Figure 3 shows another embodiment of the superconducting cable according to the present invention, Figure 4 is a cross-sectional view of the superconducting cable shown in Figure 3 is installed in the horizontal direction.

A description that overlaps with the description with reference to FIGS. 1 to 4 will be omitted. 3 and 4 show a three-phase superconducting cable in which the number of core parts 100 provided in the superconducting cable is three.

The three-phase superconducting cable may have a structure in which the cooling unit 200 is shared on the outside of the three core units 100, rather than the structure in which each core unit 100 independently includes the cooling unit 200, The vacuum unit 500 outside the cooling unit 200 may also have a shared structure.

The superconducting cable shown in FIGS. 3 and 4 can also minimize the occurrence of heat intrusion toward the core, which must be maintained at a cryogenic temperature, by applying an insulating material that can minimize heat intrusion due to conduction or radiation.

In the superconducting cable 1000 having the above-described structure, the liquid first refrigerant (nitrogen) is introduced into the cooling unit 200 of the superconducting cable 1000 at a temperature of about 70K, and the core unit 100 is The superconducting wire is kept in a cryogenic state. The liquid refrigerant cooled to maintain the superconducting wire in a cryogenic state increases in temperature to about 75K to 80K, so a cooling system for re-cooling to a temperature of about 70K is required.

The cooling system may be divided into a method having a refrigerator and a decompression method using heat of vaporization of the refrigerant. The refrigerator method is a method in which a refrigerator for cooling the liquid refrigerant is separately provided.

On the other hand, Figure 5 is a schematic diagram showing a conventional reduced-pressure cooling system (3000).

Referring to FIG. 5 , the pressure-sensitive cooling system 3000 is provided along a refrigerant circulation passage 3100 connected to the cooling unit 200 of the superconducting cable 1000 through the refrigerant circulation passage 3100 . A circulation pump 3200 for circulating the first liquid refrigerant, a refrigerant tank 3400 for supplying the first liquid refrigerant to the refrigerant circulation passage 3100, and the heat of vaporization of the second refrigerant provided along the refrigerant circulation passage A pressure reduction type cooling container 3300 for cooling the liquid first refrigerant using and a heater unit 2500 configured to heat the second gaseous refrigerant to a predetermined temperature.

The pressure-sensitive cooling system 3000 is connected to the cooling unit 200 of the superconducting cable 1000 and includes a refrigerant circulation passage 3100 in which the liquid first refrigerant flowing along the cooling unit 200 circulates. . For example, as shown in the drawing, one end of a pair of superconducting cables 1000A, 1000B is connected to each other by an intermediate junction box 2400, and the other end of the superconducting cable 1000 is a terminal junction box 2000A, 2000B. ), the refrigerant circulation passage 3100 may be connected to the cooling unit 200 of the superconducting cable 1000 through the terminal junction box 2000 .

A circulation pump 3200 is provided in the refrigerant circulation passage 3100 to circulate the liquid first refrigerant. By driving the circulation pump 3200 , the liquid first refrigerant circulates through the refrigerant circulation passage 3100 and the cooling unit 200 of the superconducting cable 1000 .

When the liquid first refrigerant circulates along the refrigerant circulation passage 3100, the amount of the liquid first refrigerant may be insufficient. At this time, the refrigerant is circulated by the refrigerant tank 3400 in which the liquid first refrigerant is accommodated. The liquid first refrigerant may be replenished through the flow path 3100 . The refrigerant tank 3400 may be connected to the refrigerant circulation passage 3100 through a first valve 3600 to control the amount of the liquid first refrigerant supplemented to the refrigerant circulation passage 3100 .

On the other hand, the refrigerant circulation passage 3100 is provided with a pressure-sensitive cooling container 3300 for cooling the liquid first refrigerant circulating in the cooling unit 200 of the superconducting cable (1000). When the liquid first refrigerant is introduced into the cooling unit 200 of the superconducting cable 1000, the superconducting wire of the core part 100 of the superconducting cable 1000 is cooled to about 70K in order to maintain the cryogenic temperature state. enters the state In this case, the pressure-sensitive cooling vessel 3300 is discharged from the superconducting cable 1000 to cool the liquid first refrigerant having a temperature of about 75K to about 80K again to about 70K.

Specifically, the inside of the pressure reduction type cooling container 3300 is decompressed to a predetermined pressure, and a liquid second refrigerant is supplied to the pressure reduction type cooling container 3300 . At this time, the liquid second refrigerant is not mixed with the liquid first refrigerant and only heat exchange is performed. The refrigerant circulation passage 3100 through which the liquid first refrigerant flows is configured to pass through the reduced pressure cooling vessel 3300 . In this case, the external cross-sectional area of the refrigerant circulation passage 3100 may be widened or provided with a plurality of fins in order to promote heat exchange between the second refrigerant and the first refrigerant in the reduced pressure cooling vessel 3300 . .

Meanwhile, the second refrigerant may be of a different type from that of the first refrigerant, but may be of the same type to simplify the structure and reduce cost of the reduced pressure cooling system 3000 . Hereinafter, it is assumed that the first refrigerant and the second refrigerant are of the same type.

For example, a flow path 3500 extending from the refrigerant tank 3400 may be connected to the pressure-sensitive cooling vessel 3300 to supply the liquid second refrigerant into the pressure-sensitive cooling vessel 3300 . In this case, since the inside of the reduced pressure cooling container 3300 is in a state of being decompressed to a predetermined pressure, the liquid second refrigerant is vaporized into a gaseous refrigerant inside the reduced pressure cooling container 3300, and the heat of vaporization is taken from the surroundings. At this time, the liquid first refrigerant on the refrigerant circulation passage 3100 passing through the reduced pressure cooling vessel 3300 is cooled.

The liquid first refrigerant re-cooled as described above flows back into the cooling unit 200 of the superconducting cable 1000 through the terminal junction box 2000B on one side to cryogenically heat the superconducting wire rod of the core unit 100 . will be kept in

On the other hand, the vapor phase second refrigerant vaporized in the pressure reduction cooling vessel 3300 is discharged to the outside by the vacuum pump 3700 connected to the pressure reduction type cooling vessel 3300 and the connection passage 3800 . In this case, the temperature of the gaseous second refrigerant directly discharged from the reduced pressure cooling vessel 3300 is approximately 70K to 80K, which corresponds to a very low temperature. As described above, if the gaseous second refrigerant having a cryogenic temperature is directly introduced into the vacuum pump 3700 , failure or damage of the vacuum pump 3700 may occur. Accordingly, a vaporizer 3900 for heat exchange between the gaseous second refrigerant and the external atmosphere may be provided in the connection passage 3800 . As shown in the figure, the vaporizer 3900 is composed of a plurality of fine pipelines branched from the connection passage 3800, and increases the contact area between the gaseous second refrigerant flowing inside the pipeline and the external atmosphere. It causes heat exchange smoothly. Accordingly, the gaseous second refrigerant is heated to about 278K to 288K by the temperature of the external atmosphere and supplied to the vacuum pump 3700 .

However, in the case of the configuration including the vaporizer 3900, the gaseous second refrigerant can be sufficiently heated in summer when the external atmospheric temperature is relatively high, but the gaseous second refrigerant in winter when the external atmospheric temperature is relatively low It cannot be heated enough. For example, the temperature of the second refrigerant passing through the vaporizer 3900 in winter is about 263K or less, and an additional temperature increase of about 15K to 25K is required.

Accordingly, a heater unit 2500 configured to heat the second gaseous refrigerant supplied to the vacuum pump 3700 to a predetermined temperature is provided on the connection passage 3800 passing through the vaporizer 3900 . The heater unit 2500 additionally heats the gaseous second refrigerant to adjust the temperature of the gaseous second refrigerant flowing into the vacuum pump 3700 to approximately 278K to 288K.

The configuration of the heater unit 2500 can prevent damage to the vacuum pump 3700 by heating the gaseous second refrigerant, but additional installation of various components including a heater is required, and furthermore, the heater unit ( 2500), power supply for driving is essential. In addition, in the case of the heater unit 2500, performance degradation may occur when used for a long time, so maintenance is required.

Hereinafter, a configuration of a reduced pressure cooling system according to another embodiment that supplements the problems of the reduced pressure cooling system as described above will be described.

6 is a schematic diagram illustrating a configuration of a reduced pressure cooling system 3000 according to another embodiment.

Referring to FIG. 6 , the pressure-sensitive cooling system 3000 according to the present embodiment is provided along the refrigerant circulation passage 3100 connected to the cooling unit 200 of the superconducting cable 1000 to provide the refrigerant circulation passage 3100 . ) through the circulation pump 3200 for circulating the first liquid refrigerant, the refrigerant tank 3400 for supplying the liquid first refrigerant to the refrigerant circulation passage 3100, and the refrigerant circulation passage 3100 along the A vacuum pump 3700 for discharging the gaseous second refrigerant generated in the reduced-pressure cooling container 3300 and the vacuum pump 3700 provided and provided to cool the liquid first refrigerant by using the vaporization heat of the second refrigerant Heat exchange for performing heat exchange between the relatively high-temperature gaseous second refrigerant discharged from the pump 3700 and the relatively low-temperature second gaseous refrigerant supplied from the pressure-sensitive cooling container 3300 to the vacuum pump 3700 A portion 4000 is provided. Here, in comparison with the embodiment of FIG. 5 described above, the same components such as the superconducting cable 1000, the circulation pump 3200, the reduced pressure cooling container 3300, the refrigerant tank 3400 and the vacuum pump 3700 have the same Reference numerals have been used, and repeated descriptions will be omitted and differences will be described below.

The reduced pressure cooling system 3000 according to the present embodiment does not require a separate component for heating the gaseous second refrigerant like the heater unit 2500 of the above-described embodiment, and is discharged from the vacuum pump 3700 . The relatively low-temperature second gas-phase refrigerant is heated by using the heat of the relatively high-temperature gas-phase second refrigerant.

Specifically, when the second gaseous refrigerant is discharged by the vacuum pump 3700 , the temperature of the gaseous second refrigerant that has passed through the vacuum pump 3700 rises to approximately 323K. Accordingly, the vapor phase flowing into the vacuum pump 3700 through heat exchange between the vapor phase second refrigerant having a temperature of approximately 263K passing through the vaporizer 3900 and the vapor phase second refrigerant having a temperature of approximately 323K as described above It is possible to increase the temperature of the second refrigerant to approximately 278K to 288K.

Therefore, in this embodiment, unlike the embodiment of FIG. 5, additional components such as a heater are omitted, and the refrigerant gas exhausted from the vacuum pump 3700 flows into the vacuum pump 3700 by exhaust heat. Relatively low temperature refrigerant gas is heated to form a reduced pressure cooling system with a simple structure, and furthermore, additional external power supply is not required.

Specifically, the heat exchange unit 4000 includes a connection passage 3800 connecting the pressure-sensitive cooling vessel 3300 and the vacuum pump 3700, and the gaseous second refrigerant discharged from the vacuum pump 3700 is inside. The discharge passage 4100 may be provided adjacent to the connection passage 3800 by a predetermined overlapping length.

That is, the discharge passage 4100 extending from the vacuum pump 3700 overlaps the connection passage 3800 by a predetermined overlap length and is disposed adjacently. The relatively high-temperature second refrigerant gas exhausted from the vacuum pump 3700 flows through the discharge passage 4100 and passes through the vaporizer 3900 through the connection passage 3800 at a relatively low temperature. Since the gaseous second refrigerant gas of can raise the temperature.

In this case, as shown in FIG. 7 , the discharge passage 4100 may have a double pipe structure surrounding the connection passage 3800 . That is, the relatively low-temperature gaseous second refrigerant that has passed through the vaporizer 3900 flows through the internal connection passage 3800, and through the outside of the connection passage 3800 and the interior of the discharge passage 4100. A relatively high-temperature gaseous second refrigerant exhausted from the vacuum pump 3700 flows. Furthermore, in the case of having a double pipe structure as described above, the flow direction (A) of the second gaseous refrigerant flowing through the connection flow path 3800 and the flow direction of the gaseous second refrigerant flowing through the discharge flow path 4100 ( B) may be in opposite directions to improve the efficiency of the heat exchange.

On the other hand, the overlapping distance corresponding to the distance (or the overlapping distance) between the connection passage 3800 and the discharge passage 4100 adjacent to each other causes the temperature of the gaseous second refrigerant to damage the vacuum pump 3700 . It can be determined to be a temperature that does not do so. For example, the overlap distance may be determined such that the temperature of the second gaseous refrigerant flowing into the vacuum pump 3700 has a range of approximately 278K to 288K.

Although the present specification has been described with reference to preferred embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention as set forth in the claims described below. will be able to carry out Therefore, if the modified implementation basically includes the elements of the claims of the present invention, all should be considered to be included in the technical scope of the present invention.

100: core part
130: superconducting conductor layer
180: superconducting shielding layer
200: cooling unit
300: inner metal tube
400: insulation
500: vacuum unit
560: spacer
600: outer metal tube
700: outer jacket
1000: superconducting cable
2000: Termination box
3100: refrigerant circulation flow path
3200: circulation pump
3300: pressure-sensitive cooling vessel
3400: refrigerant tank
3700: vacuum pump
3900 : carburetor

Claims (8)

It includes a core part having a superconducting conductor layer, a cooling part for cooling the core part with a liquid first refrigerant on the outside of the core part, a heat insulating part provided on the outside of the cooling part, and a vacuum part provided on the outside of the heat insulating part In the pressure-sensitive cooling system of a superconducting cable,
a circulation pump provided along a refrigerant circulation passage connected to the cooling unit of the superconducting cable to circulate the liquid first refrigerant through the refrigerant circulation passage;
a refrigerant tank supplying the liquid first refrigerant to the refrigerant circulation passage;
a pressure reduction type cooling vessel provided along the refrigerant circulation passage to cool the liquid first refrigerant by using the vaporization heat of the second refrigerant;
a vacuum pump for discharging the gaseous second refrigerant generated in the reduced pressure cooling vessel; and
and a heat exchange unit for performing heat exchange between the relatively high-temperature second refrigerant discharged from the vacuum pump and the relatively low-temperature second gas-phase refrigerant supplied from the reduced-pressure cooling container to the vacuum pump; and
The heat exchange unit includes: a connection passage connecting the pressure reduction type cooling vessel and the vacuum pump; and a discharge passage in which the gaseous second refrigerant discharged from the vacuum pump flows along the inside, and is provided adjacent to the connection passage by a predetermined overlapping length;
The pressure-sensitive cooling system of the superconducting cable, characterized in that the overlapping length is determined so that the temperature of the second gaseous refrigerant flowing into the vacuum pump through the connection passage is in the range of 278K to 288K. delete The method of claim 1,
the heat exchange unit
The pressure-sensitive cooling system for a superconducting cable, characterized in that the discharge passage has a double pipe structure surrounding the connection passage. 4. The method of claim 3,
A pressure-sensitive cooling system for a superconducting cable, characterized in that the flow direction of the second gaseous refrigerant flowing along the connection flow path and the flow direction of the gaseous second refrigerant flowing along the discharge flow path are opposite to each other. delete The method of claim 1,
The pressure-sensitive cooling system of the superconducting cable, characterized in that it further comprises a vaporizer for heat exchange between the second refrigerant in the gas phase and the external atmosphere on the connection passage. The method of claim 1,
The pressure-sensitive cooling system of the superconducting cable, characterized in that the first refrigerant and the second refrigerant are of the same type. According to claim 1,
The refrigerant circulation passage is a pressure-sensitive cooling system for a superconducting cable, characterized in that it is connected to the cooling unit of the superconducting cable through a terminal junction box connected to the superconducting cable.

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