KR102366614B1 - Refrigerant Pipe And Superconducting Cable Having The Same - Google Patents

Abstract

The present invention relates to a refrigerant pipe in which a core of a superconducting cable is accommodated, a refrigerant flows, and a refrigerant pipe capable of minimizing a differential pressure loss and reducing a diameter of a superconducting cable by reducing flow resistance of the refrigerant, and a superconducting cable having the same.

Description

Refrigerant pipe and superconducting cable having same

The present invention relates to a refrigerant pipe and a superconducting cable having the same. More particularly, the present invention relates to a refrigerant tube in which the core of a superconducting cable is accommodated, a refrigerant flows, and the flow resistance of the refrigerant is reduced to minimize differential pressure loss and reduce the diameter of the superconducting cable, and to a superconducting cable having the same.

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

A superconducting power system including a superconducting cable cools a core including a superconducting wire in a superconducting cable by flowing a liquid refrigerant in a state in which the core is accommodated in a refrigerant metal tube. In addition, a heat insulator for preventing external heat intrusion by winding a heat insulating material or the like on the outside of the refrigerant metal tube through which the refrigerant flows, and a vacuum metal tube provided with a spacer so as to form a vacuum part outside the heat insulating part may be provided.

The refrigerant metal tube or vacuum metal tube constituting the superconducting cable may be configured to have a corrugation structure in which troughs and ridges are repeated in order to secure bending characteristics and improve rigidity.

However, in the case of a refrigerant metal tube, since cryogenic liquid refrigerant flows inside, the corrugation structure with repeated valleys and ridges causes flow resistance of the liquid refrigerant. problems that cause losses. When the differential pressure loss increases, the load of the equipment for cooling and circulating the liquid refrigerant may increase and the stability of the superconducting condition may be deteriorated.

In addition, a method of increasing the inner diameter of the refrigerant metal tube may be considered as a method of reducing the differential pressure loss of the liquid refrigerant, but this is not preferable because the diameter of the entire superconducting cable is increased.

Republic of Korea Patent No. 10-1676199 (Registration Announcement on November 15, 2016)

The present invention is to provide a refrigerant pipe in which the core of the superconducting cable is accommodated, the refrigerant flows, and the flow resistance of the refrigerant is reduced to minimize the differential pressure loss and reduce the diameter of the superconducting cable, and a superconducting cable having the same. do it with

In order to solve the above problems, the present invention provides a refrigerant pipe for a superconducting cable in which a liquid refrigerant for cryogenic cooling of a core including a superconducting conductor layer provided with a superconducting wire flows, the refrigerant pipe comprising a non-metal inner tube and the It is possible to provide a refrigerant pipe for a superconducting cable, characterized in that it comprises a metal reinforcing material of a metal material surrounding the inner tube.

In this case, a fiber layer may be provided between the inner tube of the refrigerant tube and the metal reinforcement.

In addition, the fiber layer may be formed by traversing the outer side of the inner tube with at least one layer of a yarn composed of yarn, or wrapping a cloth woven with yarn around the outer side of the inner tube with at least one layer or more.

Here, the thickness of the fiber layer may be greater than the thickness of the inner tube and the metal reinforcement.

In addition, the inner tube of the refrigerant tube may have a pipe structure in which the inner surface and the outer surface are flat.

And, the inner tube of the refrigerant tube may be made of a polyethylene material.

In this case, the polyethylene may be fluorinated polyethylene.

Here, the metal reinforcing material may be a metal braided member.

In this case, the metal reinforcement may be a stainless steel tape.

In addition, the stainless steel tape may be spirally wound on the outside of the inner tube.

Here, the stainless steel tape may be cross-wound to overlap a predetermined range in the width direction, and the stainless steel tape may be formed to have a step difference in the overlapping range so that an upper region and a lower region have different heights.

In addition, the stainless steel tape is spirally wound so as to overlap within a certain range in the width direction, and the ends of the stainless steel tape in the width direction are opposite to each other so that the area disposed at the upper portion and the area disposed below are mutually locked in the overlapping range. It may have a bent hook shape.

In addition, in order to solve the above problems, the present invention provides a core including a superconducting conductor layer provided with a superconducting wire, a refrigerant flows for cooling the core, and vacuum insulates the refrigerant pipe and the outside of the refrigerant pipe To this end, it is possible to provide a superconducting cable including a vacuum unit partitioned by a metal tube.

According to the refrigerant pipe and the superconducting cable having the same according to the present invention, it is possible to reduce the flow resistance of the refrigerant flowing inside the refrigerant pipe by replacing the refrigerant pipe of the conventional corrugation structure with a refrigerant pipe of a flat structure.

In addition, according to the refrigerant pipe and the superconducting cable having the same according to the present invention, the flow resistance of the refrigerant flowing inside the refrigerant pipe can be minimized, so that the differential pressure loss when the refrigerant flows in the installation section of the superconducting cable can be minimized. there is.

In addition, according to the refrigerant pipe and the superconducting cable having the same according to the present invention, since the refrigerant pipe of the conventional corrugation structure can be replaced with the refrigerant pipe of the flat structure, the effect of reducing the diameter of the superconducting cable can be obtained. there is.

In addition, according to the refrigerant pipe and the superconducting cable having the same according to the present invention, it is possible to minimize the differential pressure loss during the flow of the refrigerant in the installation section of the superconducting cable, so that the cooling performance of the superconducting power system is improved, and the performance of the superconducting power system can improve

In addition, according to the refrigerant pipe and the superconducting cable having the same according to the present invention, it is possible to reduce the cooling or circulating load of the system by applying the refrigerant pipe having a flat structure, which enables the installation of a long length of the superconducting cable.

1 shows a multi-stage stripped perspective view of an embodiment of a refrigerant pipe and a superconducting cable having the same according to the present invention.
Figure 2 shows a multi-stage stripped perspective view of another embodiment of the refrigerant pipe and the superconducting cable having the same according to the present invention.
Figure 3 shows a cross-sectional view of one embodiment of the refrigerant tube of the superconducting cable according to the present invention.
4 shows a cross-sectional view and a side cross-sectional view of another embodiment of the refrigerant tube of the superconducting cable according to the present invention.

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.

1 is a perspective view showing a step-by-step stripped superconducting cable to which a refrigerant pipe 300 according to the present invention is applied.

The basic structure of the superconducting cable to which the refrigerant pipe 300 according to the present invention is applied will be described.

The former 110 provides a place for mounting a flat, 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 FIG. 1, the former may be configured in a form in which the center is full, but the former 110 is formed in a hollow pipe shape to serve as a frame for raising the superconducting wire and at the same time to move the refrigerant therein. It may be configured to serve as a path, and each of the conductor wires 111 constituting the former may be made of copper or the like, and by connecting each wire in parallel with each superconducting wire, short circuit of the power system in the power system It can also be configured to act as a return conductor when a fault current occurs due to (chilling, lightning, 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.

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 131 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. For example, AC power transmission is also possible by configuring the superconducting layer in three layers, and supplying R-phase, S-phase, and T-phase currents for each layer. In this case as well, each superconducting conductor layer must be insulated from each other.

In addition, each of the superconducting wires constituting the respective superconducting conductor layers 130a and 130b may be connected in parallel with each of the individual 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 very low temperatures for superconductivity of superconducting wires, There is a problem, and since the oil filled cable may cause environmental problems, the superconducting cable to which the refrigerant pipe 300 according to the present invention is applied may use general paper-made insulating paper as the insulating layer 160 , , the insulating layer 160 may be configured by winding 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 FIG. 1, the smooth layer and the semiconducting layer are shown to be composed of a single layer of the same material, but various auxiliary layers may be added as needed. can

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 circulation flow path of the liquid refrigerant therein. Liquid nitrogen may be used as the liquid refrigerant, and the liquid refrigerant (liquid nitrogen) circulates through the coolant flow path in a cooled state to have a temperature of about -200 degrees below zero 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.

A refrigerant pipe 300 may be provided outside the cooling unit 200 to partition the cooling unit. The refrigerant pipe 300 serves as an exterior of the superconducting cable to prevent mechanical damage to the core part 100 during the installation and operation of the superconducting cable together with the external metal pipe 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.

The refrigerant pipe 300 of a general superconducting cable is made of a material such as aluminum having a corrugation structure in which troughs and ridges are repeated in the longitudinal direction of the superconducting cable to reinforce rigidity against mechanical stress, but the refrigerant pipe according to the present invention ( 300) employs a refrigerant pipe 300 having a structure to be described later in order to minimize differential pressure loss due to flow resistance.

The refrigerant pipe 300 according to the present invention may include an inner tube 310 made of a non-metal material, a fiber layer 330 provided outside the inner tube 310 , and a metal reinforcement member outside the fiber layer 330 .

That is, since the inner tube 310 of the refrigerant tube 300 through which the refrigerant flows is configured in the form of a flat pipe, the differential pressure loss of the refrigerant due to flow resistance is lower than that of the conventional refrigerant tube (eg, 5.5 mbar/m). It was confirmed that it can be reduced to about 1/3 of the size compared to that. By this effect, it is possible to obtain the effect of reducing the cooling or circulating load of the system.

In this way, since the refrigerant pipe 300 according to the present invention is applied instead of the corrugated structure to reduce the cooling or circulating load of the system, it means that the superconducting cable can be installed in a long length.

A detailed structure or material of the refrigerant pipe 300 according to the present invention will be described later with reference to FIGS. 3 and 4 .

A heat insulating part 400 including a heat insulating layer in which several layers of a heat insulating material in which a polymer having low thermal conductivity is thinly coated on a metal film having a high reflectance and a low thermal conductivity is wound on an outer circumferential surface of the refrigerant pipe 300 may be provided. The heat insulating layer may be provided to constitute a multi-layer insulation (MLI) and to block heat intrusion into the refrigerant pipe 300 from occurring.

In particular, since the refrigerant pipe 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.

The number of layers of the insulating part 400 can be adjusted to minimize heat intrusion. If it is composed of many layers, the effect of blocking radiant heat increases, but the effect of blocking conduction heat and the effect of blocking heat by convection as the thickness of the vacuum layer decreases as the thickness of the vacuum layer decreases, so it is important to use an appropriate number of layers.

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 FIG. 1 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 to which the refrigerant pipe 300 according to the present invention is applied. 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.

Fluorinated polyethylene (PTFE, Poly Tetra Fluoro Ethylene) material forms a very stable compound due to the strong chemical bond between fluorine and carbon. there is. 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 external metal pipe 600 may be made of the same shape and material as the refrigerant pipe 300 , and the external metal pipe 600 has a larger diameter than the refrigerant pipe 300 and is passed through the 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).

2 shows a multi-stage stripped perspective view of an embodiment of a refrigerant pipe 300 and a superconducting cable having the same according to the present invention. A description that overlaps with the description with reference to FIG. 1 will be omitted.

Specifically, FIG. 2 shows a perspective view of a three-core superconducting cable for transmission or distribution of three-phase electric power.

The three-phase coaxial superconducting cable 1000 according to the present invention is provided with a superconducting conductor layer 130 for passing a first phase current, a second phase current, and a third phase current having a phase difference of 120 degrees, respectively, laminated on the same axis can be

Specifically, the three-phase coaxial superconducting cable 1000 according to the present invention sequentially surrounds the first refrigerant pipe 300a in which the liquid refrigerant flows in one direction, and the first refrigerant pipe 300a in a mutually insulated state. First to third superconducting conductor layers (130a, 130b, 130c) comprising a plurality of superconducting wires (SC) arranged side by side in the longitudinal direction of the first refrigerant pipe (300a); Among the first to third superconducting layers 130a, 130b, and 130c, the third superconducting conductor layer 130c and the third superconducting conductor layer 130c are insulated from each other and arranged side by side to surround the circumference of the third superconducting conductor layer 130c It may be configured to include a core 100 including a shielding layer 180 configured to include a plurality of conductor wires c.

The first refrigerant pipe 300a and the second refrigerant pipe 300b may be provided on the innermost and outermost sides of the core 100 constituting the three-phase coaxial superconducting cable 1000 according to the present invention.

In FIG. 2 to be described later, in the superconducting cable, the coolant flow path for cooling the core 100 is formed in one direction, but in the case of the three-phase coaxial superconducting cable 1000, the coolant flow path may be formed in both directions, and the coolant pipe 300 is also It may be provided inside and outside the core, respectively.

That is, when the liquid refrigerant flows in one direction in the first refrigerant pipe 300a provided in the innermost portion of the core 100, the liquid refrigerant flows in the second refrigerant tube 300b provided in the outermost direction of the core 100 in the one direction. may flow in the opposite direction. In this way, the first to third superconducting conductor layers 130a, 130b, 130c and the shielding layer 180 constituting the core 100 can be cooled to cryogenic temperatures, and the refrigerant recovery pipe is omitted in the superconducting power system. The effect can be obtained, and the diameter can be greatly reduced compared to the conventional three-phase superconducting cable, and the shielding layer using the superconducting wire can be omitted.

The first refrigerant pipe 300a and the second refrigerant pipe 300b may have the structure of the refrigerant pipe 300 described above. That is, the first refrigerant pipe (300a) and the second refrigerant pipe (300b) may be composed of an inner tube (310), a fiber layer (330) and a metal reinforcement material (350), each of the first refrigerant tube (300a) and a second refrigerant pipe 300b to be described later may form flow paths 200a and 200b for liquid refrigerant, respectively.

A first superconducting conductor layer 130a to a third superconducting conductor layer 130c may be sequentially stacked around the first refrigerant pipe 300a.

A cushion layer for protecting the superconducting conductor layer 130 by using a smoothing layer or semiconducting carbon paper tape for smoothing the convex and convex surfaces of the first refrigerant pipe 300a on the surface of the first refrigerant pipe 300a etc. may be provided.

A first superconducting conductor layer 130a may be provided on the surface of the first refrigerant pipe 300a. The first superconducting conductor layer 130a may be configured by arranging a plurality of superconducting wires SC side by side.

1, the first superconducting conductor layer 130a to the third superconducting conductor layer 130c are shown to be composed of a single layer, but depending on the capacity of each phase current, the superconducting wire (SC) is stacked in multiple layers. may be

In the case where at least one superconducting conductor layer 130 of the first superconducting conductor layer 130a to the third superconducting conductor layer 130c is configured by stacking superconducting wires SC, the current conduction direction is unified and An insulating tape or insulating sheet (not shown) may be provided to prevent the skin effect.

And, each of the first superconducting conductor layer 130a to the third superconducting conductor layer 130c and the shielding layer 180 must be insulated from each other because a current having a phase difference or a shielding current flows.

Accordingly, insulating layers 160a, 160b, and 160c may be provided between the first superconducting conductor layer 130a to the third superconducting conductor layer 130c and the shielding layer 180 .

The insulating layers 160a, 160b, and 160c are provided for the purpose of increasing dielectric strength, and paper-based insulating paper may be applied, and may be configured by winding the insulating paper a plurality of times, and the insulating paper may be kraft paper or PPLP (Polypropylene). Laminated Paper) can be applied is the same as in the above-described embodiment.

As shown in FIG. 1, the first to third superconducting layers 130a, 130b, and 130c are each configured in the form of a flat strip, have a constant pitch in the longitudinal direction of the cable, and are transversely wound in a spiral. can form.

The helical transverse winding directions of the superconducting wires SC constituting the first to third superconducting layers 130a, 130b, and 130c may be opposite to each other in adjacent layers.

And, although not shown in FIG. 1, in the case of a three-phase coaxial cable according to the present invention, a general conductor having the same shape as a superconducting wire is placed on the upper or lower portion of each of the first to third superconducting layers 130a, 130b, and 130c. The wire rod may be spirally cross-wound to have a predetermined pitch to provide a return conductor layer.

As described above, an insulating layer is provided outside the third superconducting conductor layer 130c disposed on the outermost side among the first to third superconducting conductor layers 130a, 130b, and 130c, and a shielding layer 180 is provided on the insulating layer. ) may be provided.

When the first to third superconducting layers 130a, 130b, and 130c have the same magnitudes of the first phase current, the second phase current and the third phase current and maintain a phase difference of 120 degrees, the induced magnetic field is also mutually Since the current flowing through the shielding layer 180 is not large due to the offset, the shielding layer 180 may be formed of a general conductor wire (c).

In addition, although not shown in FIG. 1, a semiconducting layer, etc. may be provided inside or outside each superconducting conductor layer 130, etc. to relieve the concentration of an electric field generated at the edge of the superconducting wire and to make the electric field distribution even. The semiconducting layer may be formed by winding the semiconducting tape in multiple layers.

The second refrigerant pipe 300b through which the liquid refrigerant for cooling the core 100 flows in the one direction and the opposite direction may be provided outside the core 100 . One of the first refrigerant pipe 300a and the second refrigerant pipe 300b is supplied with a cooled refrigerant, and the other refrigerant pipe 300 may be used as a pipe through which the refrigerant used for cooling is recovered. .

The superconducting cable may be provided with an intermediate junction box at a predetermined interval of the installation section, and a terminal junction box and a cooling device may be provided at both ends of the installation section. Therefore, the cooling device raises the pressure and the cooled refrigerant is supplied through a superconducting cable to be used for cooling the core 100, and the recovered refrigerant is re-supplied after gas-liquid separation, pressure reinforcement and cooling in the cooling device can be used. .

Accordingly, in the superconducting cable according to the present invention, the first refrigerant pipe 300a is provided on the innermost side of the cable, and the second refrigerant pipe 300b is provided on the outer side of the core 100, so that the Since one may be used as a path for supplying the refrigerant, and the other may be used as a path through which the refrigerant is recovered, a separate refrigerant recovery pipe may not be provided in a junction box or the like.

A heat insulating part 400 may be provided outside the second refrigerant pipe 300b. The heat insulator 400 may be configured in a manner in which a metal film having a high reflectivity is coated with a thin layer of a polymer having a low thermal conductivity and wound in several layers.

A vacuum unit 500 may be provided outside the heat insulating unit 400 , and at least one spacer 560 made of a material having low thermal conductivity, etc. may be provided in the vacuum unit 500 .

Since the vacuum metal tube 600 is not a configuration in which the flow resistance of the refrigerant is not a problem, in order to reinforce the rigidity against mechanical stress, a material such as aluminum or SUS is used, and the elevation and depression are repeated in the longitudinal direction for bending properties It may have a corrugated structure.

An external jacket 700 may be provided outside the vacuum metal tube 600 . The outer jacket 700 may be made of the same material as a conventional power cable. For example, the outer jacket 700 may be made of PE and PVC materials.

The external jacket 700 prevents corrosion of the metal tube and protects the cable from external force.

Hereinafter, the refrigerant pipe 300 that minimizes the flow resistance of the refrigerant in the superconducting cable shown in FIGS. 1 and 2 will be described in detail.

Figure 3 shows a cross-sectional view of one embodiment of the refrigerant tube 300 of the superconducting cable according to the present invention.

In the present invention, the superconducting cable uses a refrigerant tube 300 of a new structure without using a metal tube of a conventional corrugation structure for the refrigerant tube 300 through which the refrigerant flows in order to minimize the differential pressure loss due to the flow resistance of the refrigerant. .

Specifically, as shown in FIG. 3, the refrigerant pipe 300 for a superconducting cable according to the present invention includes an inner tube 310 made of a non-metal material and a metal reinforcement 350 made of a metal material surrounding the inner tube 310. characterized in that it is composed.

In the embodiment shown in FIG. 3 , an inner tube 310 is provided in the innermost portion of the refrigerant tube 300 . The inner tube 310 of the refrigerant tube 300 may be made of a polyethylene material or a fluorinated polyethylene material, and the inner tube 310 of the refrigerant tube 300 may have a pipe structure in which an inner surface and an outer surface are flat. .

Since the inner tube 310 has a flat structure, the flow resistance of the liquid refrigerant flowing inside the inner tube 310 can be significantly reduced compared to the case of the conventional metal tube having a corrugated structure.

In addition, since the inner tube 310 may be made of a polyethylene material or a fluorinated polyethylene material, external heat transfer is smaller than that of a conventional metal tube.

In addition, since the inner tube 310 may be made of a polyethylene material or a fluorinated polyethylene material, flexibility can be greatly improved compared to a conventional metal tube.

Since the conventional refrigerant pipe 300 is made of a metal material, a corrugation structure in which the troughs and ridges are repeated is adopted for the refrigerant pipe 300 in order to solve the problem that bending is not easy and is easily crushed. Due to such a corrugation structure, the metal refrigerant pipe 300 has the advantage of improved bending characteristics and reinforced rigidity against external impact, but the problem of greatly increasing the flow resistance of the refrigerant flowing inside induced.

This flow resistance results in a differential pressure loss, resulting in a cooling load or flow load in the cooling system or circulation system of the superconducting power system.

Accordingly, the refrigerant pipe 300 for superconducting cables according to the present invention adopts a flat inner tube 310 made of a resin material, rather than a corrugated structure in which troughs and ridges are repeated, to prevent a loss of differential pressure and at the same time to prevent a loss in bending characteristics or Flexibility was secured.

However, a metal reinforcing material 350 is provided on the outside of the inner tube 310 in order to reinforce the rigidity and the role of the return conductor of the fault current provided by the conventional metal tube.

That is, the conventional refrigerant pipe 300 is made of aluminum or stainless steel, and serves as a return conductor of a fault current to some extent with the former when a problem occurs in the cooling system, etc., but the inner pipe 310 is made of polyethylene, etc. In the case of replacing it with a resin material, it cannot be used as a return conductor, and since it does not have sufficient rigidity against the load or external impact of the cable, the metal reinforcement 350 may be provided on the outside of the inner tube 310 .

In the embodiment shown in FIG. 3 , the metal reinforcement 350 may be formed of a metal braided member.

The metal braided member is a member composed of a thin metal wire like a cloth, and is configured to wrap along the outermost portion of the inner tube 310 to serve as a return conductor of the fault current and reinforce rigidity.

And, as shown in the cross-sectional view of FIG. 3 , a fiber layer 330 may be provided between the inner tube 310 of the refrigerant tube 300 and the metal reinforcement 350 .

The fiber layer 330 forms a minimum thickness of the refrigerant pipe 300, and prevents the impact directly applied to the inner pipe 310 by the metal reinforcement 350, etc. to protect the inner tube 310. can

The fiber layer 330 is a method of winding a yarn composed of a yarn on the outside of the inner tube 310 with at least one layer or more, or wrapping a cloth woven with yarn around the outer side of the inner tube 310 with at least one layer or more. It may be configured to have a thickness of a certain degree.

In addition, as shown in FIG. 3 , the fiber layer 330 preferably has a thickness greater than that of the inner tube 310 and the metal reinforcement 350 .

4 shows a cross-sectional view and a side cross-sectional view of another embodiment of the refrigerant pipe 300 of the superconducting cable according to the present invention. A description that overlaps with the description with reference to FIG. 3 will be omitted.

In the above embodiment, the metal reinforcement material was a braided member, but the metal reinforcement material 350 of the embodiment shown in FIG. 4 may be a stainless steel tape.

As shown in FIG. 4( b ), the stainless steel tape is spirally wound on the outside of the inner tube 310 so that the inner inner tube 310 or the fiber layer 330 is not exposed to the outside.

And, as shown in Fig. 4(b), when the stainless steel tape 350a is applied as the metal reinforcement 350, the stainless steel tape 350a does not overlap with an adjacent area, and is rolled across without a gap. The outer surface may be configured in a flat state, but the stainless steel tape 350a may be cross-winded so that a gap or play between the tapes that may be generated during bending of the refrigerant pipe 300 does not occur.

Specifically, as shown in the longitudinal sectional view of the refrigerant pipe 300 of FIGS. 4(c) and 4(d), the stainless steel tapes 350b and 350c are transversely wound to overlap a certain range in the width direction, and the The stainless steel tape has a step difference so that the regions 351b and 351c disposed on the upper part and the regions 352b and 352c disposed on the lower part have different heights in the overlapping range to make the surface of the refrigerant pipe 300 as flat as possible. configurable.

Here, when the stainless steel tape has a thin thickness, a step may be naturally formed in the transverse winding process, but when the stainless steel tapes 350b and 350c have a certain thickness, the stainless steel tape has a step (s) in advance. It can also be processed.

Furthermore, in addition to forming the step (s) in the stainless steel tape for flatness of the surface, it is possible to have a locking or locking structure so that the wound state of the stainless steel tape 350c is not affected by bending of the cable.

Specifically, as shown in FIG. 4 , the stainless steel tape 350c is spirally wound to overlap a certain range in the width direction, and the stainless steel tape is disposed in the upper region 351c and the lower portion in the overlapping range. Self-locking or locking the wound state of the stainless steel tape 350c by making the width direction ends each have a hook shape bent in the opposite direction so that the regions 353c are mutually locked so that they are locked to each other. It is possible to prevent the occurrence of gaps or gaps.

As described above, according to the refrigerant pipe and the superconducting cable having the same according to the present invention, the refrigerant pipe of the conventional corrugation structure is replaced with a refrigerant pipe of a flat structure to minimize the flow resistance of the refrigerant flowing inside the refrigerant pipe. Therefore, it is possible to minimize the differential pressure loss when the refrigerant flows in the installation section of the superconducting cable, and it is possible to replace the refrigerant pipe of the conventional corrugation structure with the refrigerant pipe of the flat structure, so that the diameter of the superconducting cable can be reduced. effect can be obtained, and since the differential pressure loss can be minimized when the refrigerant flows in the section where the superconducting cable is installed, the cooling performance of the superconducting power system can be improved, thereby improving the performance of the superconducting power system Since it is possible to reduce the cooling or circulating load of the system by applying the tube, it can enable the long-term installation of superconducting cables.

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 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.

1000: superconducting cable
300: refrigerant pipe

Claims (13)

In the refrigerant pipe for a superconducting cable in which a liquid refrigerant for cryogenic cooling of a core including a superconducting conductor layer provided with a superconducting wire flows,
The refrigerant pipe is configured to include an inner tube made of a non-metal material and a metal reinforcement material made of a metal material surrounding the inner tube,
The inner tube of the refrigerant tube has a pipe structure in which an inner surface and an outer surface are flat,
A refrigerant tube for a superconducting cable, characterized in that a fiber layer is provided between the inner tube of the refrigerant tube and the metal reinforcement. delete According to claim 1,
The fiber layer is a superconducting cable refrigerant tube, characterized in that it is composed of a method of winding a yarn composed of a yarn in at least one layer on the outside of the inner tube, or wrapping a cloth woven with yarn around the outer side of the inner tube in at least one layer or more. According to claim 1,
Refrigerant tube for superconducting cable, characterized in that the thickness of the fiber layer is greater than the thickness of the inner tube and the metal reinforcement. delete According to claim 1,
The refrigerant tube for a superconducting cable, characterized in that the inner tube of the refrigerant tube is made of a polyethylene material. 7. The method of claim 6,
The polyethylene is a refrigerant pipe for a superconducting cable, characterized in that the fluorinated polyethylene. According to claim 1,
The metal reinforcing material is a refrigerant pipe for a superconducting cable, characterized in that the metal braid member. According to claim 1,
Refrigerant pipe for superconducting cable, characterized in that the metal reinforcement is a stainless steel tape. 10. The method of claim 9,
The stainless steel tape is a refrigerant pipe for a superconducting cable, characterized in that it is spirally wound on the outside of the inner tube. 11. The method of claim 10,
The stainless steel tape is transversely wound so as to overlap a certain range in the width direction, and the stainless steel tape is formed to be stepped so that an upper region and a lower region have different heights in the overlapping range. refrigerant pipe. 10. The method of claim 9,
The stainless steel tape is spirally wound so as to overlap a certain range in the width direction, and the ends of the stainless steel tape are bent in opposite directions in the overlapping range so that the upper region and the lower region are mutually locked. Refrigerant tube for superconducting cable, characterized in that it has a hook shape. a core including a superconducting conductor layer provided with a superconducting wire;
A refrigerant flows for cooling the core, and the refrigerant pipe of any one of claims 1, 3, 4, and 6 to 12; and,
A superconducting cable comprising a;

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