KR20190004443A - Corrugated Refrigerant Metal Pipe And Superconducting Cable Having The Same - Google Patents

Abstract

The present invention discloses a refrigerant metal pipe with a corrugated structure and a superconducting cable having the corrugated structure, in which the core of the superconducting cable is accommodated and the refrigerant flows, and the fluid resistance of the refrigerant is reduced to minimize a differential pressure loss.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a refrigerant metal pipe having a corrugated structure and a superconducting cable having the same,

The present invention relates to a refrigerant metal tube having a corrugated structure and a superconducting cable having the same. More particularly, the present invention relates to a refrigerant metal tube having a corrugated structure and a superconducting cable having the same, wherein a core of a superconducting cable is accommodated and a refrigerant flows, and a flow resistance of the refrigerant is reduced to minimize a differential pressure loss.

The superconducting wire has a large power transmission capability even at a low voltage since the electric resistance converges near zero at a constant temperature. A superconducting cable having such a superconducting wire uses a method of cooling by using a coolant such as nitrogen and / or a method of forming a vacuum layer to insulate the superconducting cable in order to form and maintain a cryogenic environment.

The superconducting power system including the superconducting cable cools the core by flowing the liquid coolant while the core is accommodated in the coolant metal tube to cool the core including the superconducting wire in the superconducting cable. The refrigerant pipe may be provided with a heat insulating portion for preventing the heat from entering the refrigerant pipe through which the refrigerant flows, and a vacuum metal pipe having a spacer may be provided on the outer side of the heat insulating portion to form a vacuum portion.

The metal tubes constituting the superconducting cable can be configured so as to have a corrugated structure in which the bending property is secured and the bones and the floor are repeated in order to improve the rigidity.

However, in the case of the refrigerant metal tube, since the cryogenic liquid refrigerant flows in the inside, the corrugation structure in which the valleys and the floor are repeated causes the flow resistance of the liquid refrigerant. Such a flow resistance increases as the length of installation of the superconducting cable becomes longer, Causing a problem causing loss.

If the differential pressure loss is increased, the load of the equipment for cooling and circulating the liquid coolant may be increased and the stability of the superconducting condition may be lowered.

Also, a method of increasing the inside diameter of the refrigerant metal tube by reducing the differential pressure loss of the liquid refrigerant can be considered, but this is not preferable because the diameter of the entire superconducting cable is increased.

The present invention provides a refrigerant metal pipe having a corrugated structure and a superconducting cable having the same, which can accommodate a core of a superconducting cable and flow the refrigerant, thereby minimizing the differential pressure loss by reducing the flow resistance of the refrigerant. .

In order to solve the above problems, the present invention provides a refrigerant pipe for a superconducting cable for accommodating a core including a superconducting conductor layer including a superconducting wire of a superconducting cable and a liquid refrigerant for cryogenic cooling of the core, The refrigerant metal pipe has a corrugation structure in which the valleys and the floor are repeated. The interval between the floor of the refrigerant metal pipe and the highest point of the floor or the lowest point of the valley is defined as a pitch P, And the pressure drop per unit length of the refrigerant metal pipe of the liquid refrigerant flowing in the refrigerant metal pipe is defined as the differential pressure loss PL, P, the wave height (H), and the differential pressure loss (PL) satisfy the following relationship.

- Down -

(PL) = a - b * pitch (P) + c * wave height (H), the constants a, b and c are positive real numbers and the constants are 1.2 <a <1.6, 0.2 < 2.8 < c < 3.2, and the unit of the differential pressure loss PL is mbar / m, and the unit of the pitch P and the height H is mm.

In this case, the minimum internal diameter d of the refrigerant metal tube determined by the crests and ridges of the refrigerant metal tube is 50 mm or more and 70 mm or less, and the maximum external diameter D of the refrigerant metal tube is 80 mm to 100 mm Can be satisfied.

The differential pressure loss PL may be measured at a distance of 6 m to 10 m of the refrigerant pipe, by a pressure difference between a refrigerant inlet at one end of the refrigerant pipe and a refrigerant outlet at the other end.

Here, the flow rate of the liquid phase refrigerant supplied through the refrigerant inlet at the distance d may be 20 (ℓ / min, LPM) to 180 (ℓ / min, LPM).

Further, the refrigerant is liquid nitrogen, and the flow rate of the liquid nitrogen per hour may be 0.8 kg / s to 1.2 kg / s.

The pitch (P), the internal minimum diameter (d) of the refrigerant metal tube and the internal minimum diameter (d) of the refrigerant metal tube are set so that the differential pressure loss PL satisfies a value in the range of 4 mbar / m to 6 mbar / (D) of the outer diameter D of the outer diameter D2 of the outer diameter D2.

According to another aspect of the present invention, there is provided a superconducting cable comprising: a core including a superconducting layer including a superconducting wire; The refrigerant pipe for a superconducting cable according to claim 1, which accommodates the core and flows with liquid refrigerant. A heat insulating portion formed by horizontally inserting a heat insulating material outside the refrigerant metal tube; A vacuum chamber provided outside the heat insulating portion; An external refrigerant metal pipe arranged to be spaced apart from the heat insulating portion by the vacuuming; And an outer jacket surrounding the outer refrigerant metal tube.

Also, the minimum internal diameter d of the refrigerant metal pipe determined by the crests and ridges of the refrigerant metal pipe is 50 mm or more and 70 mm or less, and the maximum external diameter D of the refrigerant metal pipe is 80 mm to 100 mm .

In addition, the differential pressure loss PL can be measured at a refrigerant inlet of one end of the refrigerant metal tube and at a refrigerant outlet of the other end at a distance of 6 m to 10 m from the refrigerant metal tube.

The flow rate of the liquid refrigerant supplied through the refrigerant inlet at the distance d may be 20 (l / min, LPM) to 180 (l / min, LPM).

The refrigerant is liquid nitrogen, and the flow rate of the liquid nitrogen per hour may be 0.8 kg / s to 1.2 kg / s.

The pitch (P), the internal minimum diameter (d) of the refrigerant metal tube and the internal minimum diameter (d) of the refrigerant metal tube are set so that the differential pressure loss PL satisfies a value in the range of 4 mbar / m to 6 mbar / (D) of the outer diameter D of the outer diameter D2 of the outer diameter D2.

According to the refrigerant metal pipe of the corrugated structure and the superconducting cable having the corrugated structure according to the present invention, the pitch and the size of the refrigerant metal pipe are optimized to minimize the flow resistance of the refrigerant flowing in the refrigerant metal pipe.

Further, according to the refrigerant metal pipe having the corrugation structure and the superconducting cable having the corrugated structure according to the present invention, since the flow resistance of the refrigerant flowing in the refrigerant metal pipe can be minimized, the differential pressure loss Can be minimized.

Further, according to the refrigerant metal pipe having the corrugation structure and the superconducting cable having the corrugated structure according to the present invention, it is possible to minimize the differential pressure loss when the refrigerant flows in the installation section of the superconducting cable, thereby improving the cooling performance of the superconducting power system .

FIG. 1 is a perspective view of a coolant metal tube of a corrugated structure according to the present invention and a multistage peeled perspective view of one embodiment of the superconducting cable having the same.
FIG. 2 is a perspective view of a refrigerant metal tube of a corrugated structure according to the present invention and a multi-stage unmolded perspective view of another embodiment of the superconducting cable having the same.
3 is a perspective view of a refrigerant tube of the superconducting cable shown in FIG. 1 or FIG. 2 and a sectional view of a part of the section.
Fig. 4 shows a configuration diagram of a test apparatus for measuring a differential pressure loss of a refrigerant metal tube of a superconducting cable.
Fig. 5 shows the relationship between the pitch of the refrigerant metal tube of the corrugation structure, the wave height and the differential pressure loss 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 but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Like reference numerals designate like elements throughout the specification.

FIG. 1 is a perspective view of a refrigerant metal pipe having a corrugation structure according to the present invention and a superconducting cable having the same according to one embodiment of the present invention. FIG. 2 is a perspective view showing a refrigerant metal pipe having a corrugation structure according to the present invention, Lt; RTI ID = 0.0 &gt; of &lt; / RTI &gt; another embodiment of the cable.

1 and 2 will be described with reference to a superconducting cable for three-phase power supply, but the same applies to a single-phase superconducting cable.

Specifically, Fig. 1 shows a perspective view of a three-core superconducting cable for three-phase power transmission or distribution.

The three-phase coaxial superconducting cable 1000 according to the present invention includes a superconducting conductor layer 130 for coaxially stacking a first phase current, a second phase current, and a third phase current for 120 degrees of phase difference, .

More specifically, the three-phase coaxial superconducting cable 1000 according to the present invention includes a first refrigerant pipe 300a through which the liquid refrigerant flows in one direction, and a second refrigerant pipe 300b through which the first refrigerant pipe 300a is sequentially insulated First to third superconducting conductor layers (130a, 130b, 130c) including a plurality of superconducting wires (SC) arranged side by side in the longitudinal direction of the first refrigerant metal tube (300a); The first superconducting conductor layer 130c and the third superconducting conductor layer 130c are arranged in a state of being insulated from the third superconducting conductor layer 130c disposed at the outermost one of the first through third superconducting conductor layers 130a 130b, And a shielding layer 180 including a plurality of conductor wires (c).

The first refrigerant metal pipe 300a and the second refrigerant metal 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.

The refrigerant metal tubes according to the present invention are characterized in that the structure is optimized as described later to minimize the differential pressure loss due to the flow resistance of the refrigerant. A detailed description will be given later with reference to FIG. 3 and the following.

2, which will be described later, the flow path of the coolant 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 can be formed in both directions, Respectively.

That is, when the liquid refrigerant flows in one direction from the first refrigerant metal tube 300a provided at the innermost portion of the core 100, the liquid refrigerant in the second refrigerant metal tube 300b provided at the outermost portion of the core 100 flows in the one direction As shown in FIG. In this way, the first to third superconducting conductor layers 130a, 130b, and 130c and the shielding layer 180 constituting the core 100 can be cooled at a very low temperature.

The first refrigerant metal pipe 300a and the second refrigerant metal pipe 300b may be made of aluminum or steel and may be made of aluminum or stainless steel to reinforce rigidity against mechanical stress. And may have a corrugated structure in which protrusions and depressions are repeated in the longitudinal direction. Each of the first refrigerant metal pipe 300a and the second refrigerant metal pipe 300b described later may form the flow paths 200a and 200b of the liquid refrigerant.

The first superconducting conductor layer 130a to the third superconducting conductor layer 130c may be sequentially stacked around the first coolant metal tube 300a.

A smooth layer or a semi-conductive carbon paper tape for smoothing the convex surface of the surface of the first refrigerant metal pipe 300a is formed on the surface of the first refrigerant metal pipe 300a so that a cushion layer for protecting the superconducting conductor layer 130 And the like.

The 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 formed by arranging a plurality of superconducting wires SC in parallel.

1, the first superconducting layer 130a to the third superconducting layer 130c are formed of a single layer. However, the superconducting layers SC may be stacked in a multilayer structure according to the capacity of each phase current. It is possible.

When at least one superconducting conductor layer 130 of the first superconducting conductor layer 130a to the third superconducting conductor layer 130c is formed by stacking the superconducting wires SC, An insulating tape or an insulating sheet (not shown) may be provided to prevent the skin effect.

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

Accordingly, insulating layers 160a, 160b and 160c may be provided between the first superconducting conductor layer 130a and 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 the dielectric strength, and may be formed of a paper-like insulating paper or a plurality of times of insulating paper. Generally, a polymer material such as XLPE is mainly used for insulation of a high-voltage cable, but there is a problem that it is broken at a cryogenic temperature. Therefore, in case of a superconducting cable in which insulation performance should be maintained in a cryogenic environment, paper paper may be used.

The insulating paper may be made of kraft paper or PPLP (Polypropylene Laminated Paper). The PPLP (polypropylene laminated paper) insulating paper has characteristics of excellent ease of winding and excellent dielectric strength.

As shown in FIG. 1, the first to third superconducting conductor layers 130a, 130b, and 130c are each formed in the form of a flat strip. Each of the first to third superconducting conductor layers 130a, 130b, and 130c has a constant pitch in the longitudinal direction of the cable, Can be formed.

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

Although not shown in FIGS. 1 and 2, in the case of the three-phase coaxial cable according to the present invention, the same or the same shape as that of the superconducting wire may be formed on the upper or lower portion of each of the first to third superconducting conductor layers 130a, 130b, The conductive conductor layer may be provided with a spiral-shaped transversely extending conductor layer so as to have a predetermined pitch.

As described above, an insulating layer is provided outside the third superconducting conductor layer 130c disposed at the outermost one of the first through third superconducting conductor layers 130a, 130b, and 130c, and a shielding layer 180 May be provided.

When the first to third superconducting conductor layers 130a, 130b and 130c have the same first phase current, the second phase current and the third phase current and have a phase difference of 120 degrees, The current flowing through the shielding layer 180 is not large and the shielding layer 180 may be composed of the common conductor wire c.

However, when the first phase current, the second phase current, and the third phase current flowing through the respective cores differ in size or can not maintain a phase difference of 120 degrees each, the shielding layer composed of the common conductor wire has a large shielding current In this case, since the shield layer 180 composed of the common conductor wire c may have a large heat generation, the shield layer 180 may include at least one superconducting wire (not shown) have.

Although not shown in FIG. 1, a semiconductive layer or the like may be provided inside or outside each of the superconducting conductor layers 130 and the like in order to alleviate the electric field concentration generated at the corner portions of the superconducting wire and to smooth the electric field distribution. The semiconductive layer can be constituted by a method of winding a semi-conductive tape in multiple layers.

The second refrigerant pipe (300b) may be provided outside the core (100), in which liquid refrigerant for cooling the core (100) flows in a direction opposite to the one direction. Any one of the first refrigerant metal pipe 300a and the second refrigerant metal pipe 300b may be used as a pipe for supplying the cooled refrigerant and the other refrigerant metal pipe for recovering the refrigerant used for cooling.

The superconducting cable is provided with an intermediate connection box at a predetermined interval of the installation section, and both ends of the installation section are provided with a terminal connection box, a cooling device, and the like. Accordingly, the cooling apparatus can be used in which the pressure is increased and the cooled refrigerant is supplied to the core 100 through the superconducting cable and the recovered refrigerant is re-supplied after the gas-liquid separation, pressure strengthening and cooling in the cooling apparatus .

Therefore, in the superconducting cable according to the present invention, the first refrigerant metal pipe 300a is provided on the inner side of the cable, the second refrigerant metal pipe 300b is provided on the outer side of the core 100, One may be used as a path for supplying refrigerant and the other may be used as a path for recovering refrigerant, so that a separate refrigerant recovery pipe may not be provided in a connection box or the like.

The second refrigerant metal pipe 300b forms a flow path for the liquid refrigerant like the first refrigerant metal pipe 300a and uses a material such as aluminum or SUS for reinforcing the mechanical stress against rigidity. And may have a corrugated structure in which protrusions and depressions are repeated in the longitudinal direction.

Since the second refrigerant pipe 300b also needs to reduce the flow resistance of the refrigerant to minimize the differential pressure loss, it is necessary to perform the following structural optimization like the first refrigerant pipe 300a.

The heat insulating part 400 may be provided outside the second refrigerant metal pipe 300b. The heat insulating part 400 may be formed by winding a heat insulating material having a thin film of a polymer having a low thermal conductivity coated on a metal film having a high reflectance.

The number of layers of the heat insulating material wound to form the heat insulating part 400 can be adjusted in order to minimize the heat penetration. As the number of layers increases, the radiation heat blocking effect increases. However, It is necessary to use an appropriate number of floors because the heat blocking effect is lowered. The heat insulating portion 400 can prevent the heat exchange due to heat insulation and radiation or the prevention of heat intrusion.

A vacuum 500 may be provided outside the heat insulating part 400. The vacuum chamber 500 refers to a space inside the vacuum metal pipe 600 for receiving the heat insulating part 400. The vacuum cleaner 500 vacuumizes the inside of the vacuum metal pipe 600 to heat the convection heat between the heat insulating part 400 and the vacuum metal pipe 600 Intrusion and the like can be prevented. However, if the heat insulating part 400 and the vacuum metal pipe 600 are brought into contact with each other, conduction heat may be generated, so that the thermal insulating part 400 and the vacuum metal pipe 600 are prevented from coming into contact with each other. The vacuum chamber 500 may be provided with at least one spacer 560 having a low thermal conductivity.

The spacer 560 prevents the vacuum metal pipe 600 and the like provided on the outer side of the spacing space in the vacuum chamber 500 from contacting the heat insulating part 400 inside the vacuum chamber 500 in the entire area of the superconducting cable. At least one, typically three to four, spacers 560 in the spacing space.

The spacer 560 may be made of polyethylene (FEP, PFA, ETFE, PVC, PE or PTFE), and the spacer 560 may be made of PTFE (Poly Tetra Fluoro Ethylene) Or the back surface composed of a general resin or a polyethylene material may be coated with fluorinated polyethylene or the like. In the case of fluorinated polyethylene (e.g., Teflon), the thermal conductivity is low, which is advantageous in minimizing conduction heat penetration. In addition, when the spacer 560 is formed of the fluorinated polyethylene material, frictional damage or deformation due to the metal tube is minimized due to characteristics such as a perfect chemical inertness and heat resistance, non-stickiness, excellent insulation stability, and low friction coefficient in addition to low thermal conductivity .

The spacer 560 may have a shape such as a circular polygon, or may be hollow. The maximum width of the spacer 560 may be about 4 millimeters (mm) to 8 millimeters (mm).

The vacuum metal pipe 600 is made of a material such as aluminum or stainless steel to reinforce rigidity against the mechanical stress as in the case of the refrigerant metal pipe 300. The vacuum metal pipe 600 is corrugated ).

An outer jacket 700 may be provided outside the vacuum metal pipe 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.

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

The superconducting cable shown in FIG. 2 can supply three-phase superconducting power similarly to the superconducting cable shown in FIG. 1, but a structure in which superconducting layers are stacked, Lt; / RTI &gt;

The superconducting cable shown in FIG. 2 has a single refrigerant metal tube in a cable in which a refrigerant recovery pipe is separately provided, has three independent cores in a refrigerant metal tube , and has a first phase current having a phase difference of 120 degrees , The second phase current and the third phase current (R, S, T phase) can flow.

Each of the first core, the second core and the third core comprises a common conductor Former , Superconductivity around the former Wire Rod (SC)  The superconductivity for power supply Conductor layer (130), the superconducting The conductor layer 130  Wrapping paper Insulating layer , remind Insulating layer  Superconducting Wire Rod (SC)  The shielded current Energizing  And a shielding layer 180 for shielding the shielding layer.

Then, three  The cores 100a, 100b, and 100c are accommodated in one refrigerant metal tube 300, and liquid refrigerant for forming a cryogenic condition, which is a superconducting condition, flows through the refrigerant metal tube and cools the three cores together.

Unlike the refrigerant recovery pipe in which the refrigerant is recovered, the refrigerant metal pipe 300 greatly influences the stability of the system when a pressure loss is generated. Therefore, the flow resistance of the refrigerant must be minimized. It is the same.

In addition, the refrigerant metal tube 300 is being wrapped around the insulating portion 400 to primarily prevent heat penetration by radiation on the outer peripheral surface, the heat insulating part 400 outward, the study true for preventing wear a yeolchim of convection or conduction (500) may be provided.

remind The vacuum chamber 500  remind The heat- (400) Lateral  Means a space between the vacuum metal pipes 600, Jean (Not shown) The heat insulating portion 400 and  In order to prevent contact of the vacuum metal pipe 600 The spacers 560  At least one may be provided. The vacuum metal pipe (600) Outside  As with general power cables, Outer jacket (700) and the like.

3 is a perspective view of a refrigerant tube of the superconducting cable shown in FIG. 1 or FIG. 2 and a sectional view of a part of the section.

A refrigerant metal tube for a superconducting cable in which a liquid refrigerant flows for cryogenic cooling of a core including a superconducting conductor layer provided with a superconducting wire, The distance between the floor of the refrigerant metal pipe and the highest point of the floor or the distance between the lowest point of the floor and the bottom of the refrigerant metal pipe is defined as a pitch P and the difference between the highest point of the floor and the lowest point of the bottom (H) and the pressure drop per unit length of the refrigerant metal pipe of the liquid refrigerant flowing in the refrigerant metal pipe is defined as a differential pressure loss PL, the pitch P, The differential pressure loss PL can satisfy the following relationship. In this case, the differential pressure loss PL = a - b * pitch P + c * wave height H, constants a, b and c are positive real numbers, and respective constants are 1.2 <a <1.6 and 0.2 <b <0.3 and 2.8 <c <3.2. The unit of the differential pressure loss PL is mbar / m, and the unit of the pitch P and the height H is mm.

As shown in FIG. 3 (a), the coolant metal tube for a superconducting cable according to the present invention may be constructed to have a corrugated structure composed of aluminum or SUS and having repeated valleys and floors.

The pitch (P) means the distance between the valley of the refrigerant metal pipe and the peak (H), and the pitch (P) is the distance between the bottom of the refrigerant pipe and the bottom of the refrigerant metal pipe. Means the maximum height difference between the valley of the refrigerant metal pipe and the floor. That is, the method of the above-mentioned wave height (H) can be determined by a method of measuring the height difference between the maximum point of the floor and the lowest point of the valley on the surface of the refrigerant metal tube.

The inside diameter of the refrigerant metal tube means the inside diameter of the refrigerant metal tube which is the refrigerant flow path and the minimum inside diameter means the minimum diameter of the inside surface of the refrigerant metal tube in which the valley and the floor are repeated, The diameter means the maximum diameter on the basis of the cross-section of the outer surface of the refrigerant metal pipe.

The minimum inner diameter d of the refrigerant metal pipe determined by the valley and the floor of the refrigerant metal pipe is 50 mm or more and 70 mm or less in order to flow the sufficient refrigerant and to limit the size of the total diameter of the superconducting cable, And the maximum outer diameter D of the protruding portion is preferably 80 mm to 100 mm.

And the differential pressure loss means a pressure drop according to the unit length interval of the refrigerant flowing through the refrigerant metal pipe.

Fig. 4 shows a configuration diagram of a test apparatus for measuring a differential pressure loss of a refrigerant metal tube of a superconducting cable.

The test method for measuring the differential pressure loss may be a method of supplying the liquid refrigerant at the inlet of the refrigerant metal tube having a sufficient length, recovering the refrigerant at the outlet of the refrigerant metal tube, and circulating the refrigerant by pumping the refrigerant.

Therefore, the differential pressure loss measuring apparatus shown in Fig. 4 stores the cryogenic liquid refrigerant in the refrigerant tank and supplies the liquid refrigerant stored in the tank to the inlet of the refrigerant metal tube by the pump p.

In this case, the total length XL of the refrigerant metal tube may be 10 m or more, and the differential pressure loss may be measured at the inlet or outlet of the refrigerant metal tube, but is preferably measured in the normal flow of the refrigerant Therefore, each pressure in a predetermined section of the refrigerant metal pipe can be measured and the difference can be judged as the differential pressure loss.

That is, as shown in Fig. 4, a first point X1 of a predetermined distance 7 m to 9 m (L, where L < XL) of the refrigerant metal tube having an overall length TL of 10 m The first pressure sensor ps1 and the second pressure sensor ps2 are provided at the second point X2 to determine the difference between the measured first pressure p1 and the second pressure p2 as a differential pressure.

The flow rate of the liquid refrigerant (liquid nitrogen) supplied through the inlet (i) of the distance L satisfies the range of 20 (l / min, LPM) to 180 (l / min, LPM) Is controlled to be about 0.8 kg / s to 1.2 kg / s.

A temperature sensor Ts, a pressure sensor Ps and a flow rate sensor Fs are provided on a pipe for supplying refrigerant from the tank to the inlet of the refrigerant metal pipe in order to determine whether or not the normal test conditions are maintained, The state of the refrigerant can be monitored, and the flow rate can be controlled by providing at least one valve (v).

Fig. 5 shows the relationship between the pitch of the refrigerant metal tube of the corrugation structure, the wave height and the differential pressure loss according to the present invention.

As described above, the pitch P, the wave height H and the differential pressure loss PL of the refrigerant metal pipe according to the present invention are calculated by the following equation: PL = a - b * pitch P + ), Respectively. Here, the constants a, b, and c satisfy the ranges 1.2 <a <1.6, 0.2 <b <0.3, and 2.8 <c <3.2.

5, the pressure loss PL was measured while varying the pitch P and the peak height H, respectively. The graph of each color shows the relationship between the wave height H and the differential pressure loss PL in a state where the value of the pitch P is fixed.

It can be confirmed that the differential pressure loss PL with respect to each pitch P has a tendency of a linear function form with respect to the wave height H and concretely the differential pressure loss PL is proportional to the wave height H . It is understood that when the wave height (H) is increased, the flow resistance is increased in the course of the flow of the liquid refrigerant, which is advantageous in terms of bending property or stiffness, but turbulence generated inside the flow path causes pressure loss.

And the blue horizontal line of the graph shown in Fig. 5 typically indicates the upper limit of the differential pressure loss required. That is, for example, when the permissible value of the differential pressure loss is 5 mbar / m, it means that the pitch P and the wave height H can be determined such that the differential pressure loss of the system is 5 mbar / m or less.

Specifically, in the state where the diameter of the cable, that is, the minimum inner diameter d of the refrigerant metal pipe and the maximum outer diameter D of the refrigerant metal pipe are determined by the power capacity or the like in the designing process of the system, The size of the pitch P and the height H can be determined so as to satisfy a specific value in the range of 4 mbar / m to 6 mbar / m.

Of course, the flow rate of the liquid refrigerant (liquid nitrogen) under the condition that the differential pressure loss PL is below a specific value in the range of 4 mbar / m to 6 mbar / m in the state where the pitch P and the wave height H are determined, The minimum inner diameter d of the refrigerant metal tube and the maximum outer diameter D of the refrigerant metal tube may be determined so as to satisfy the condition of 20 (l / min, LPM) to 180 (l / min, LPM).

In this way, by optimizing the pitch and the height of the refrigerant metal pipe, the flow resistance of the refrigerant flowing in the refrigerant metal pipe can be minimized, minimizing the differential pressure loss of the refrigerant, and improving the cooling performance and stability of the superconducting power system .

While the present invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims. . It is therefore to be understood that the modified embodiments are included in the technical scope of the present invention if they basically include elements of the claims of the present invention.

Claims (12)

A refrigerant pipe for a superconducting cable in which a liquid refrigerant flows for cryogenic cooling of a core including a superconducting conductor layer having superconducting wires,
The refrigerant metal pipe has a corrugation structure in which the valley and the floor are repeated. The interval between the floor of the outer surface of the refrigerant metal pipe and the highest point of the floor or the interval between the lowest point of the valley and the bottom of the valley is defined as a pitch P, And the pressure drop per unit length of the refrigerant metal pipe of the liquid refrigerant flowing in the refrigerant metal pipe is defined as a differential pressure loss PL,
Wherein the pitch (P), the wave height (H), and the differential pressure loss (PL) satisfy the following relationship.
- Down -
(PL) = a - b * pitch (P) + c * wave height (H),
The constants a, b, and c are positive real numbers, and each constant satisfies a range of 1.2 <a <1.6, 0.2 <b <0.3 and 2.8 <c <
The unit of the differential pressure loss PL is mbar / m, and the unit of the pitch P and the height H is mm. The method according to claim 1,
The minimum inner diameter d of the refrigerant metal pipe determined by the valley and the floor of the refrigerant metal pipe is 50 mm or more and 70 mm or less and the maximum outer diameter D of the refrigerant metal pipe is 80 mm to 100 mm A refrigerant metal tube for a superconducting cable characterized by: The method according to claim 1,
The differential pressure loss PL is measured at a first point X1 and a second point X2 of a predetermined distance 7 m to 9 m (L, where L < XL) Wherein the refrigerant pipe is a pressure difference. The method of claim 3,
Wherein the flow rate of the liquid refrigerant supplied through the refrigerant inlet at the distance d is 20 (l / min, LPM) to 180 (l / min, LPM). 5. The method of claim 4,
Wherein the refrigerant is liquid nitrogen and the flow rate of the liquid nitrogen per hour is 0.8 kg / s to 1.2 kg / s. 3. The method of claim 2,
Wherein the differential pressure loss PL is less than or equal to a specific value in a range of 4 mbar / m to 6 mbar / m in a state where the minimum inner diameter d of the refrigerant metal pipe and the maximum outer diameter D of the refrigerant metal pipe are determined And the size of the pitch (P) and the height (H) of the refrigerant pipe are determined. A core comprising a superconducting conductor layer comprising a superconducting wire of a superconducting cable;
The refrigerant pipe for a superconducting cable according to claim 1, which accommodates the core and flows with liquid refrigerant.
A heat insulating portion formed by horizontally inserting a heat insulating material outside the refrigerant metal tube;
A vacuum chamber provided outside the heat insulating portion;
An external refrigerant metal pipe arranged to be spaced apart from the heat insulating portion by the vacuuming; And
And an outer jacket surrounding the outer refrigerant metal tube. 8. The method of claim 7,
The minimum inner diameter d of the refrigerant metal pipe determined by the valley and the floor of the refrigerant metal pipe is 50 mm or more and 70 mm or less and the maximum outer diameter D of the refrigerant metal pipe is 80 mm to 100 mm Features superconducting cable. 8. The method of claim 7,
The differential pressure loss PL is measured at a first point X1 and a second point X2 of a predetermined distance 7 m to 9 m (L, where L < XL) Wherein the superconducting cable is a pressure difference. 10. The method of claim 9,
Wherein a flow rate of the liquid phase refrigerant supplied through the refrigerant inlet of the distance L is 20 (l / min, LPM) to 180 (l / min, LPM). 11. The method of claim 10,
Wherein the refrigerant is liquid nitrogen, and the flow rate of the liquid nitrogen per hour is 0.8 kg / s to 1.2 kg / s. 9. The method of claim 8,
Wherein the differential pressure loss PL is less than or equal to a specific value in a range of 4 mbar / m to 6 mbar / m in a state where the minimum inner diameter d of the refrigerant metal pipe and the maximum outer diameter D of the refrigerant metal pipe are determined And determining the size of the pitch (P) and the height (H) of the superconducting cable.

Images