WO2015005530A1

WO2015005530A1 - Multipath cross flow heat exchanger

Info

Publication number: WO2015005530A1
Application number: PCT/KR2013/008586
Authority: WO
Inventors: 양형석; 황시돌; 손송호; 임성우; 임지현; 장호명; 박찬우; 곽경현
Original assignee: 한국전력공사
Priority date: 2013-07-12
Filing date: 2013-09-25
Publication date: 2015-01-15
Also published as: KR102001250B1; US20160109183A1; KR20150008310A

Abstract

The present invention relates to a multipath cross flow heat exchanger and, more particularly, to a multipath cross flow heat exchanger, capable of preventing degradation of the cooling performance of a superconductor which may occur when circulation of liquid nitrogen in a circulation tube is not smooth, by forming cooling tubes, in which a refrigerant for cooling liquid nitrogen is distributed, to intersect multiple times with the circulation tube, in which the liquid nitrogen is circulated, to thereby freeze the liquid nitrogen by the refrigerant.

Description

Multi-channel flow heat exchanger

The present invention relates to a multi-channel AC heat exchanger, and more particularly, a cooling tube through which a refrigerant for cooling liquid nitrogen is circulated to a circulation tube through which liquid nitrogen is circulated is formed so as to cross a plurality of times. It is related to a multi-channel AC heat exchanger that can prevent the cooling of the superconductor due to the freezing of the liquid nitrogen in the circulation tube is not smooth circulation.

The present invention claims the benefit of the filing date of Korean Patent Application No. 10-2013-0082388 filed on July 12, 2013, the entire contents of which are incorporated herein.

A superconductor is a conductor that exhibits a superconducting phenomenon of near zero electrical resistance at very low temperatures. The superconductor cannot enter a magnetic field and pushes the magnetic field inside out, indicating a magnetic levitation phenomenon.

Superconductors having these properties can be used in the field of current limiters, magnetic levitation technology, and power transmission.

In particular, in the case of the transmission field, the longer the length of the superconducting cable, the more external heat infiltration increases, and when an AC current flows in the superconducting cable, the temperature increases due to the AC loss, causing a power loss, thereby increasing the cooling load. do.

In other words, in order to keep the resistance close to 0 using the characteristics of the superconductor, it is very important to cool the superconductor so that it can continuously maintain a low temperature such as cryogenic temperature.

As described above, in order to maintain the superconducting element in a cryogenic state, cryogenic liquid nitrogen for cooling the superconducting cable is used. The liquid nitrogen cools the liquid nitrogen because the temperature of the liquid nitrogen increases due to heat exchange with the superconducting cable. Another cooling system must be in place.

Prior art related to this is disclosed in Korean Patent Publication No. 2009-0124825 (2009.12.03. Publication, cooling system of superconducting current limiter using solidification refrigerant).

The present invention has been made in order to solve the above problems, the cooling tube for cooling the cooling fluid flows to the circulation pipe through which the cooling fluid for cooling the superconducting cable is installed so as to cross a plurality of times. It is an object of the present invention to provide a multi-channel ac heat exchanger which prevents freezing of the cooling fluid and does not reduce cooling performance.

In accordance with the above configuration, the present invention has an object to provide a heater for preventing the freezing of the cooling fluid, or a heat exchanger that does not need to install a heater.

In order to solve the above problems,

The present invention includes a circulation tube through which a cooling fluid for cooling a superconducting cable is distributed, and a cooling tube through which a refrigerant heat-exchanging with the cooling fluid is formed by forming a flow path crossing the circulation tube a plurality of times.

The circulation pipe and the cooling pipe cross each other in a state in which the cooling fluid inside the circulation pipe and the refrigerant inside the cooling pipe are not mixed with each other.

The cooling tube, when the cooling fluid flows from one side of the circulation tube to the other side, the portion where the refrigerant flowing in the cooling tube crosses the circulation tube for the first time is located on the other side of the circulation tube, inside the cooling tube The portion where the refrigerant after the heat exchange with the cooling fluid crosses the circulation pipe again is formed to be located on one side of the circulation pipe.

The diameter of the cooling tube is formed to be larger than the diameter of the circulation tube, and at the portion where the circulation tube and the cooling tube intersect, the circulation tube is located inside the cooling tube, so that the cooling tube is formed on the outer surface of the circulation tube. The cooling fluid and the refrigerant are heat-exchanged through the outer surface of the circulation pipe that crosses.

The cooling tube is a housing shape having a space formed therein, wherein the space is formed at any one of a body part installed to include a predetermined portion of the circulation pipe and an outer surface of the body part to supply the refrigerant to the space part. Is formed in the other of the supply portion and the outer surface of the body portion includes a discharge portion for the refrigerant supplied to the space flows out.

The circulation pipe may be branched into a plurality of branch pipes in which the circulation pipe has a smaller diameter in a region where the circulation pipe crosses the cooling pipe.

The supply unit and the discharge unit are formed on any one side with respect to the circulation pipe across the body portion is formed spaced apart from each other on the outer surface of the cooling tube.

The body portion may further include a partition wall disposed in the space portion formed inside the body portion, and provided between the supply portion and the discharge portion, wherein the coolant supplied to the supply portion is provided in the space portion. An opening portion through which the refrigerant may pass may be formed to be discharged to the discharge portion.

By the means for solving the above problems,

The present invention has the effect of preventing the cooling performance from being lowered while preventing the freezing of the cooling fluid.

Accordingly, the present invention also has the effect that it is not necessary to install a heater or a heater for preventing the freezing of the cooling fluid.

1 illustrates an embodiment of a multi-pass ac heat exchanger in accordance with the present invention.

2 is a diagram showing a heat exchange schematic diagram of another embodiment of the multi-channel AC heat exchanger according to the present invention;

3 illustrates various embodiments of a multi-pass ac heat exchanger in accordance with the present invention.

4 is a view showing an overview of the cooling fluid behavior and temperature distribution of the multi-pass AC heat exchanger according to the present invention.

5 is a view showing an outline of the cooling fluid behavior and temperature distribution of the countercurrent heat exchanger.

FIG. 6 is a view showing an outline of cooling fluid behavior and temperature distribution of an alternating heat exchanger; FIG.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

Here, detailed descriptions of well-known functions and configurations that may unnecessarily obscure the repeated description and the gist of the present invention will be omitted.

And embodiments of the present invention is provided to more completely explain the present invention to those skilled in the art.

Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity.

1 is a view showing an embodiment of a multi-pass AC heat exchanger according to the present invention.

Referring to FIG. 1, an exemplary embodiment of a multi-channel AC heat exchanger according to the present invention includes a circulation pipe 100 through which a cooling fluid for cooling a superconducting cable is distributed, and a plurality of crossings of the circulation pipe 100. A cooling pipe 200 is formed to form a flow path through which the refrigerant that exchanges heat with the cooling fluid is distributed therein.

Here, the heat exchange process in which the cooling fluid is cooled by the refrigerant while the circulation pipe 100 and the cooling pipe 200 cross each other, is a cooling fluid in the circulation pipe 100 and an inside of the cooling pipe 200. Allow the refrigerants to cross each other in isolation from each other so that they do not mix with each other.

That is, the refrigerant and the cooling fluid are not mixed with each other, but are exchanged with each other with the outer surface of the circulation pipe 100 through which the cooling fluid flows.

The circulation tube 100 and the cooling tube 200 may be heat exchanged in the following shape.

The cooling pipe 200 has a housing shape in which a space S is formed therein, and the body portion 210 is installed to include a predetermined portion of the circulation pipe 100 in the space S, and the body. Is formed in any one of the outer surface of the portion 210 is formed in the other of the outer surface of the supply portion 220 and the body portion 210 to supply the refrigerant to the space (S) to the space (S) And a discharge part 230 through which the supplied refrigerant flows out.

As shown in FIG. 1, the supply part 220 and the discharge part 230 are formed to be spaced apart from each other on one side (the same side) based on the circulation pipe 100 crossing the body part 210. Can be.

Referring to the process of heat exchange between the cooling fluid and the refrigerant by using the heat exchanger of the present invention shown in FIG. 1 as an example, the cooling fluid is circulated from the left side to the right side of the circulation pipe 100, and the refrigerant is supplied to the supply unit 220. And heat exchanged with the cooling fluid circulated therein while being in contact with the outer surface of the circulation pipe 100 in the body 210, and then discharged through the discharge unit 230 again.

In particular, by using the heat exchanger according to the present invention by the above configuration, it is possible to maintain efficient cooling performance while preventing the freezing of the cooling fluid. The heat exchange process will be described in more detail as follows.

2 is a diagram showing a heat exchange schematic diagram of another embodiment of the multi-channel AC heat exchanger according to the present invention.

Referring to FIG. 2, when the cooling fluid flows from one side of the circulation pipe 100 to the other direction, the cooling pipe 200 is connected to the circulation pipe 100 with the refrigerant flowing in the cooling pipe 200. The first portion P1 intersecting is positioned at the other side of the circulation tube 100, and the portion where the refrigerant after the heat exchange with the cooling fluid in the cooling tube 200 crosses the circulation tube 100 again ( P2) is characterized in that it is formed to be located on one side of the circulation pipe (100).

As shown in FIG. 2, the circulation pipe 100 includes a plurality of branch pipes having a smaller diameter in the circulation pipe 100 in a region where the circulation pipe 100 intersects the cooling pipe 200. It may be branched to 110.

As such, by selectively connecting the branch pipe 110 to the circulation pipe 100 in a facility using a superconducting cable, it is possible to further improve the cooling performance of the heat exchanger.

The body portion 210 may further include a partition wall 240 disposed in the space S formed therein, and provided between the supply portion 220 and the discharge portion 230. The partition 240 has an opening portion 241 through which the refrigerant can pass so that the refrigerant supplied to the supply part 220 in the space S may be distributed and discharged toward the discharge part 230. ) Is formed.

That is, based on FIG. 2, the coolant is circulated in a “∩” shape in the space S to cool the cooling fluid.

Referring to Figure 2, the process of heat exchange, the cooling fluid for cooling the superconducting cable flows to cross the body portion 210 of the cooling pipe 200 from the left side to the right side of the circulation pipe (100). do.

As shown in FIG. 2, the circulation section may branch the plurality of branch pipes 110 as necessary.

Refrigerant for cooling the cooling fluid is introduced into the interior of the body portion 210, that is, the space portion (S) through the supply unit 220.

Heat exchange with the cooling fluid through the outer surface of the circulation tube 100 in the region corresponding to P1 in the space (S) to cool the cooling fluid primarily.

The refrigerant passing through the P1 region collides with the inner wall surface of the body portion 210, and the traveling direction thereof is changed to the left side of the circulation pipe 100. After passing through the area corresponding to P2 in (S) and the heat exchange again with the cooling fluid through the outer surface of the circulation tube 100 is discharged from the body portion 210 through the discharge unit 230.

The multi-channel AC heat exchanger according to the present invention may be designed in various embodiments as follows according to the cooling performance value required in the facility for cooling the superconducting cable.

3 is a diagram illustrating various embodiments of a multi-pass AC heat exchanger according to the present invention.

3 (a) is a diagram illustrating an embodiment of a structure in which the cooling fluid and the refrigerant are first cooled in the P1 region and secondly cooled in the P2 region, as described above.

Since the description thereof is the same as described above, it will be omitted.

3 (b) shows that the refrigerant having passed through the P2 region is not immediately discharged to the discharge unit 230, and the direction of travel thereof is changed again so that the cooling fluid is returned to the discharge unit 230 after three times of heat exchange. It is a discharged configuration.

As shown in (b) of FIG. 3, (c) of FIG. 3 shows that the refrigerant supplied to the supply part 220 intersects with the circulation pipe 100 four times in the space part S a total of four times. It is a figure which shows the Example in which heat exchange is performed.

4 is a view showing an overview of the cooling fluid behavior and temperature distribution of the multi-channel AC heat exchanger according to the present invention, Figure 5 is a view showing an overview of the cooling fluid behavior and temperature distribution of the countercurrent heat exchanger. 6 is a view showing the outline of the cooling fluid behavior and the temperature distribution of the heat exchanger of the alternating current system.

First, Figure 4 is a view showing the cooling fluid behavior and temperature distribution of the multi-channel AC heat exchanger according to the present invention, it can be smoothly circulated without liquid nitrogen in the circulation pipe 100 under normal load Able to know.

Here, the temperature distribution line (unit: absolute temperature, K) is concentrated at the portion where the supply unit 220 is formed and the refrigerant is not supplied, and the lowest temperature is 64K, so that the liquid nitrogen does not freeze and circulates smoothly. Can be.

In the case of low load, the lowest temperature near the supply part 220 is 63K, and the corresponding area is only a very small part, which is a freezing area of the procedure that is insignificant to prevent the circulation of liquid nitrogen in the circulation pipe 100. It is within a degree that does not disturb the circulation.

5 is a generally used counterflow method, which refers to a case in which the flow direction of the liquid nitrogen in the circulation pipe 100 and the flow direction of the refrigerant in the cooling pipe 200 are opposite to each other, and the cooling efficiency is excellent and widely. This is the way it is used.

As shown in FIG. 5, in the case of the normal load, the countercurrent system smoothly flows in the circulation pipe 100 without freezing liquid nitrogen. However, in the low load state, the minimum temperature reaches 62K, and liquid nitrogen freezes in a region corresponding to a temperature distribution line of 62K or less including a temperature distribution line near 63K.

This, in contrast to the low-loaded frozen region of FIG. 4, in the counter-current low-loaded state, a region corresponding to 62K to 63K is frozen inside the circulation tube 100 to freeze liquid nitrogen within the circulation tube 100. Due to this problem is impossible to circulate.

6 is an alternating current system, which refers to a case in which the flow direction of the refrigerant in the cooling tube 200 is perpendicular to the flow direction of the liquid nitrogen in the circulation tube 100.

In this alternating current method, as shown in FIG. 6, even in a normal load, a freezing region in which the liquid nitrogen is partially frozen is formed in the circulation tube 100. Comparing this with the low load state of Figure 4, compared to the multi-channel AC heat exchanger according to the present invention, it can be seen that the alternating current is formed in the area where the liquid nitrogen is frozen even in the normal load state.

As such, the formation of more than one third of the freezing area of the circulating area to inhibit the circulation of the liquid nitrogen even under the normal load state not only prevents the flow of the liquid nitrogen in the circulation pipe 100 but also continues the heat exchanger in this state. If you operate by installing a separate heater for stability will cause a problem that must be operated at all times.

In the case of the low load in the alternating current system, it can be seen that a larger freezing area is formed than the liquid nitrogen freezing area of the normal load.

As such, by using the multi-channel alternating heat exchanger according to the present invention, the liquid nitrogen is prevented from being frozen in the circulation pipe 100 even in a low load state as well as a normal load, or it does not prevent the flow of liquid nitrogen in the purified pipe. Since liquid nitrogen is frozen only in a very limited area, the liquid nitrogen is smoothly circulated in the circulation pipe 100, thereby preventing the cooling efficiency of the superconducting cable from being lowered.

In addition, since the freezing area of the liquid nitrogen is very small, there is no need to install a separate heater for applying heat to the circulation pipe 100 to solve this problem, thereby improving the efficiency of the cooling system and reducing energy consumption due to the operation of the heater. There is an effect that can be removed and reduced.

While specific embodiments of the present invention have been illustrated and described, the technical spirit of the present invention is not limited to the accompanying drawings and the above description, and various modifications can be made without departing from the spirit of the present invention. It will be apparent to those skilled in the art, and variations of this type will be regarded as belonging to the claims of the present invention without departing from the spirit of the present invention.

Claims

A circulation pipe through which a cooling fluid for cooling the superconducting cable is distributed; And

And a cooling tube in which a coolant to exchange heat with the cooling fluid is formed by forming a flow path that crosses the circulation pipe a plurality of times.
The method according to claim 1,

The circulation tube and the cooling tube,

And the cooling fluid inside the circulation pipe and the refrigerant inside the cooling pipe cross each other in a state in which they are not mixed with each other.
The method according to claim 1,

The cooling tube,

When the cooling fluid flows from one side of the circulation pipe to the other side,

The portion where the refrigerant circulated in the cooling pipe crosses the circulation pipe for the first time is located at the other side of the circulation pipe,

And a portion where the refrigerant after the heat exchange with the cooling fluid crosses the circulation pipe again in the cooling pipe is located at one side of the circulation pipe.
The method according to claim 1,

The diameter of the cooling tube is formed larger than the diameter of the circulation tube,

At the intersection of the circulation pipe and the cooling pipe, the circulation pipe is located inside the cooling pipe so that the cooling fluid and the refrigerant exchange heat through the outer surface of the circulation pipe crossing the cooling pipe among the outer surfaces of the circulation pipe. Multi-channel flow heat exchanger characterized.
The method according to claim 1,

The cooling tube,

A housing portion having a space formed therein, the space having a body portion installed to include a predetermined portion of the circulation pipe;

A supply unit formed at any one of an outer surface of the body part to supply the refrigerant to the space part; And

And a discharge part formed at another one of the outer surfaces of the body part to discharge the refrigerant supplied to the space part.
The method according to claim 5,

The circulation pipe,

And wherein the circulation pipe can branch into a plurality of branch pipes having a smaller diameter in an area where the circulation pipe crosses the cooling pipe.
The method according to claim 5,

The supply part and the discharge part,

The multi-pass AC heat exchanger, characterized in that formed on any one side with respect to the circulation pipe across the body portion spaced apart from each other on the outer surface of the cooling tube.
The method according to claim 6,

The body portion,

A partition wall disposed in the space part formed inside the body part and provided between the supply part and the discharge part;

The partition wall, the multi-channel AC heat exchanger is characterized in that the opening through which the refrigerant can pass so that the refrigerant supplied to the supply portion in the space portion is discharged to the discharge portion is formed.