KR20000025823A - Cryogenic cooling device using centrifugal force of rotor - Google Patents

Abstract

PURPOSE: A rotary cooling device employing the basic principle of a Roebuck cooling device using centrifugal force is provided to cool a rotating system. CONSTITUTION: A rotary cryogenic cooling device is composed of: a liquid helium storage tub(300) which is a cooling part, an eight-stage liquid neon re-condensing device(305) condensing gaseous helium to cryogenic liquid helium, a compressor(315) compressing gaseous helium mechanically, a liquid neon storage tub(320) absorbing heat generated by re-condensing gaseous helium to liquid helium, a three-stage liquid neon re-condensing device(325) condensing gaseous neon to liquid neon, another compressor(335) compressing gaseous neon mechanically, a liquid nitrogen storage tub(340) absorbing heat generated by re-condensing gaseous neon to liquid neon, and a liquid neon heat exchanger(310) and a liquid nitrogen heat exchanger(330) improving the efficiency of energy. Herein, the structure of a rotary cryogenic cooling device is simplified. And the cost for producing a device and maintaining is reduced.

Description

Cryogenic cooler using centrifugal force of rotor

FIELD OF THE INVENTION The present invention relates to cryogenic coolers, and more particularly, to rotatable cryogenic coolers for cryogenic cooling in rotatable systems.

Cryogenic coolers are particularly required in applications requiring cryogenic temperatures up to 4.2 K, the liquefaction temperature of helium, including those used in superconducting generators that presuppose liquid helium supply.

The coolers used in current superconducting generators assume the supply of liquid helium from the outside. Therefore, the structure of the cooler used in superconducting generators, including most low-temperature devices requiring high vacuum, is complicated by the various connections for helium circulation, and the cost of durability and continuous supply of liquid helium is a real problem. Was done.

Superconducting generators have advantages in terms of efficiency, size, weight, and stability compared to general generators using electromagnets, which are currently widely used, but due to the complexity of the cooler structure because the liquid helium supply device must be located outside the rotor of the generator. Due to the enormous price and the problem is not commercialized.

That is, since a device that connects the non-rotating outside and the inside of the rotating superconducting generator to allow the low-temperature fluid refrigerant to pass through is required, there is a problem that the entire structure of the superconducting generator system is complicated and inefficient.

Looking at the cryogenic cooler to the extent that the conventional helium can be liquefied as follows.

Conventional cryogenic chillers mainly use Joule-Thomson expansion chillers using the principle that the cooling effect occurs during adiabatic expansion, and FIG. 1 schematically shows the function of each device of the cryogenic chiller according to the prior art. The block diagram shown.

The conventional cryogenic cooler shown in FIG. 1 uses helium as the primary refrigerant, nitrogen as the secondary refrigerant for the purpose of heat exchange, and uses a heat exchanger, an expander, and the like to form a liquefier in a stopped state. . This is described as follows.

The gaseous helium is first compressed through the compressor 110 and then multistage adiabatic expansion (Jul-Thomson expansion) through the expanders 125, 135, 145.

The cryogenic cooler of FIG. 1 is a three-stage expansion process, in which a heat exchanger is used to circulate the helium gas immediately after each expansion and the cooling region for efficient energy management, and then to exchange heat between the cold helium gas from the cooling region. 130, 140, 150 are provided. In addition, preliminary cooling heat exchangers 115 and 120 that use liquid nitrogen as a refrigerant are also provided in case a heat exchange at this time is insufficient.

After completing the multi-stage adiabatic expansion and heat exchange process, the gas helium is condensed into liquid helium while undergoing a throttling process through the Joule-Thomson valve 155, and the cold liquid helium is cooled to the rotor 100, which is a portion to be cooled. As it flows in, it creates a cooling effect.

The liquid helium, after completion of the cooling process, is vaporized with gaseous helium and returns to the initial state 110 with heat exchange (150, 140, 130, 120) as described above.

A general cryogenic cooler according to the prior art described above is described in more detail in Cryogenic Engineering, R. B. Scott.

As described above, in the case of cooling the rotating system, the cryogenic cooler according to the prior art liquefies helium outside the stationary state, supplies helium into the rotating system, and cools the gas helium evaporated after cooling to the outside. Release and liquefy again with a liquefier.

Therefore, in the prior art using a stationary helium liquefier, the enthalpy of cold helium vapor evaporated at low temperature cannot be effectively utilized, and after the temperature of helium vapor reaches room temperature, the helium vapor is recompressed. Since the liquefaction process, the overall energy consumption efficiency is not good due to the increase of the irreversible loss work due to the heat exchange process over a large temperature range than necessary.

In addition, the supply of liquid helium from a stationary site to a rotating low temperature system involves a number of complex mechanical devices (helium circulators, rotary vacuum insulators, etc.), which complicates the overall structure, reduces the durability of the system, and The need arises for equipment.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and an object thereof is to provide a rotary cooler that uses the basic principle of a low-bucket cooling device using centrifugal force to cool a rotating system.

1 is a block diagram schematically showing the function of each device of a liquid helium cooler according to the prior art,

2A is a conceptual explanatory diagram of the operating principle of a Roebuck Cooling Device used in the present invention;

2B is a conceptual explanatory diagram when the rowbuck cooling device shown in FIG. 2A is configured in multiple stages,

Figure 3 is a block diagram schematically showing the function of each device of the rotary cooler according to an embodiment of the present invention,

4 is an explanatory view of the heat flow of the rotary cooler shown in FIG.

5A is a front view of the eight stage liquid helium recondensation apparatus and the three stage liquid neon recondensation apparatus shown in FIG.

FIG. 5B is a side view showing one unit of the eight stage liquid helium recondensation apparatus shown in FIG. 5A;

FIG. 5C is a side view showing one unit of the three-stage liquid neon recondensation apparatus shown in FIG. 5A;

6A is a temperature-entropy graph showing a thermodynamic cycle in which liquid helium is recondensed in accordance with one embodiment of the present invention,

6B is a temperature-entropy graph showing the thermodynamic cycle in which liquid neon is recondensed in accordance with one embodiment of the present invention.

♠ Explanation of symbols on the main parts of the drawing ♠

200, 515, 545: isothermal compression process

210, 520, 550: adiabatic expansion process

400: liquid helium reservoir 410: liquid neon reservoir

420: fin type heat exchanger 430, 440: mechanical compressor

500: 8 stage liquid helium recondensing unit

505: three stage liquid neon recondensing unit

510: high temperature, high pressure gas helium inflow

525, 555: branch flow of gas 530, 560: counterflow heat exchanger

535, 540: low temperature, low pressure gas inlet

According to the present invention for achieving the object as described above, the compression-expander using the property that the refrigerant gas is compressed while flowing outward in the radial direction of the rotor, and then expands while flowing inwards in the radial direction of the rotor and the In a rotary cooler comprising a counterflow heat exchanger in which gases exchange heat with each other, the compression-expander includes a multi-stage, branched flow in which a portion of the refrigerant is extracted to perform a simple Joule-Thomson expansion. Bleeding) is provided with a rotary cooler.

According to the present invention, the rotary cooler includes a plurality of cooling cells each having at least two fluids as refrigerants, and the first cooling cell in direct contact with the cooling portion is helium as the refrigerant, and the first As for the 2nd cooling cell which extracts heat from a cooling cell, it is more preferable to use neon as a refrigerant.

The basic principle of the rotary cryogenic cooler proposed by the present invention is to use the basic principle of the Roebuck Cooling Device proposed by Roebuck of the United States. This is described as follows.

In cooling or recondensing hot gases in a rotating system, passing the gas through a radially outward passageway of the center of rotation causes the gas to be compressed by centrifugal force and radially inwardly path of the center of rotation. The basic principle of the low buckles cooling device is to use the principle of expanding the gas by centrifugal force when passing through.

That is, if the gas flows in both directions of the rotation center, the gas may be compressed and expanded. At this time, the heat generated in the compression process of the gas is absorbed through the heat exchange with the cooler gas moving in the reverse direction, in the expansion process to block the heat inflow from the outside, the system is isothermal compression, adiabatic expansion process as a whole Will be able to drop the temperature. If the above process is repeated several times, the hot gas can be gradually cooled to the desired temperature.

This will be described in more detail with reference to the drawings.

2A is a conceptual explanatory diagram of the operating principle of the low-buckle cooling device.

The gas to be cooled is compressed while passing through the passage 200 away from the center of rotation. At this time, if the heat exchange with the cooler gas passing through the passage of 210 is designed to be properly isothermally compressed, the temperature T ₁ before the process of (200) is the temperature T ₂ after the process of (200) Will be equal to

Thereafter, the gas passing through the passage of 200 passes through the passage 210 toward the center of rotation and expands at the same time as heat exchange with the gas passing through the passage of 200.

At this time, if designed to block the heat inflow from the outside as much as possible, the system as a whole (200) process can be designed as an isothermal compression process, 210 process is adiabatic expansion process. Therefore, since the temperature T ₃ after the process of 210 is lower than the temperature T ₂ before the process of 210, the temperature of the gas is lowered as a result.

Looking at the size of the temperature (T) and pressure (P) at the time of the above process by position as shown in Equation (1).

After several steps like this, it is possible to cool down to a desired temperature. Conceptually, these various steps are illustrated in FIG. 2B when n steps have been performed.

As described above, the low-bucket cooling device constitutes a cooler by using the centrifugal force of the rotor, and therefore, there is an advantage that it is not necessary to provide an additional device of the cooler outside the rotor. On the other hand, as for the Roebuck cooling unit, see R. Roebuck, 1945, A novel form of refrigerator, Journal of Applied Physics. Vol. 16, May, pp. 285-295, for example.

In the following, with reference to the accompanying drawings, a preferred embodiment according to the present invention using the basic principle of a low-bucket cooling device will be described in detail.

3 is a block diagram schematically showing the function of each device of the rotary cryogenic cooler according to an embodiment of the present invention. In order to cool the helium to a cryogenic temperature (about 4.2 K), the primary refrigerant was helium (He), the secondary refrigerant was neon (Ne), and the tertiary refrigerant was nitrogen (N ₂ ). .

The rotary cryogenic cooler according to the present embodiment is a liquid helium reservoir 300 corresponding to a cooling portion, an eight-stage liquid helium recondensing apparatus 305 for condensing gas helium to cryogenic liquid helium, and mechanically compressing gas helium. Compressor 315, liquid neon reservoir 320 for absorbing heat generated when recondensing gaseous helium into liquid helium, and three stage liquid neon recondensing device 325 for condensing gaseous neon to liquid neon. ), A compressor 335 for mechanically compressing gas neon, a liquid nitrogen reservoir 340 for absorbing heat generated when recondensing gas neon with liquid neon, and a liquid neon heat exchanger 310 for increasing energy efficiency. ) And a liquid nitrogen heat exchanger 330.

Meanwhile, the liquid helium reservoir 300, the eight stage liquid helium recondensation unit 305, the compressors 315 and 335, the liquid neon reservoir 320, the three stage liquid neon recondensation unit 325, and the liquid neon heat exchanger The 310 and the liquid nitrogen heat exchanger are installed in the rotor 350 which is a cooling portion, and the liquid nitrogen storage tank 340 is installed outside the cooling portion. However, there is no mass transfer between the liquid nitrogen reservoir and the components of the cooler installed in the rotor.

Looking in detail the operating principle of the rotary cryogenic cooler configured as described above are as follows.

First, gaseous helium in a high temperature state (about 30 K) is compressed through the mechanical compressor 315, and the heat generated at this time is absorbed into the liquid neon reservoir 320 through the liquid neon heat exchanger 310. The gas helium compressed through the above process is introduced into the eight stage liquid helium recondensing unit 305 and condensed into liquid helium by the low-buckling cooling method described above. The condensed liquid helium enters the cooling site, vaporizes with gaseous helium while cooling, and returns to its initial state (315) to achieve a thermodynamic cycle.

In addition, the gas neon in a high temperature state (about 77 K) is compressed through the mechanical compressor 335, and the heat Q _N2 generated at this time is transferred to the liquid nitrogen storage tank through the liquid nitrogen heat exchanger 330 installed outside the rotor. 340 is absorbed. The gas neon compressed through the above process is introduced into the three-stage liquid neon recondensing apparatus 325 and condensed into liquid neon by the low-buckling cooling method described above. The condensed liquid neon flows into the liquid neon reservoir 320 to absorb the heat (Q _Ne ) generated when the gas helium is mechanically compressed (315) through the liquid neon heat exchanger (310), and the gas neon After evaporation, the process returns to the initial state (335) to achieve a thermodynamic cycle.

In addition, the liquid nitrogen reservoir 340 absorbs the heat Q _N2 generated when the gas neon is mechanically compressed 335 through the liquid nitrogen heat exchanger 330 having a copper disk-shaped fin attached to the outer side of the rotor. At this time, it was designed so that there is no flow of the material.

Eventually, the cooling load generated at cryogenic temperatures (approximately 4.2 K) is transferred from the liquid helium reservoir 300 to the liquid neon reservoir 320 and finally to the liquid nitrogen heat exchanger 330 having a copper disk fin through a multi-step process. It can be seen that through the external liquid nitrogen reservoir 340 through.

4 shows the heat flow of the cryogenic cooler according to an embodiment of the present invention described above.

400 is the liquid helium reservoir, which corresponds to the cooling zone, where the extracted heat is passed through the eight stage liquid helium recondensation apparatus to the liquid neon reservoir 410. The transferred heat is extracted to the outside through a liquid nitrogen heat exchanger 420 made of copper fins installed outside the rotor after passing through the three-stage liquid neon recondensation apparatus.

This method eliminates the need for complicated mechanical connections between the rotor and the stationary system, and recondensation of liquid helium uses only the centrifugal force of the rotor without the influx of energy from external inflows. It is very advantageous because it uses only cheap liquid nitrogen.

Meanwhile, the eight-stage liquid helium recondensing unit 305 and the three-stage liquid neon recondensing unit 325 of the rotary cryogenic chiller according to the present embodiment have the same structure because they use a low-buckling cooling method. There may be minor changes to suit the invention.

5A is a front view of an eight stage liquid helium recondensation apparatus and a three stage liquid neon recondensation apparatus, FIG. 5B is a side view showing one unit of the eight stage liquid helium recondensation apparatus, and FIG. 5C is a three stage liquid neon condensation apparatus. It is a side view which shows one unit of a recondensation apparatus. This will be described in detail as follows.

As shown in FIG. 5A, each recondensing unit is constructed radially from the center of rotation and designed to take advantage of centrifugal force, where 500 represents an eight stage liquid helium recondensation unit and 505 represents a three stage liquid neon. The device is displayed.

The operation of each recondensing unit will be described according to the flow of refrigerant.

5B is a side view showing the outline of the configuration of one unit of the eight-stage liquid helium recondensing apparatus.

When the gas helium to be cooled flows into the apparatus (510), it flows outward in the radial direction of the rotation center (515) and is compressed by centrifugal force. At this time, since the heat of compression is generated, the counterflow heat exchanger 530 is installed to exchange heat with the cooler gas helium 535 which is cooled and then returned to the initial state. The gas helium compressed by the centrifugal force flows inward in the radial direction of the rotation center to expand (520).

On the other hand, since the heat generated during the compression process is generally very large, a problem arises in that all the heat cannot be absorbed by the cooling capacity of the cooler gas helium 535 flowing in the reverse direction. In other words, a simple low-buck cooling method cannot produce a cryogenic temperature of 4.2K.

Therefore, the above-mentioned problem is exploited by using a cooling effect generated in the process of reducing the amount of heat generated during compression and branching expansion by blowing a portion of the gas helium to be compressed to the low temperature stage before compression occurs. Solved.

In the case of such branched expansion, there is a simple Joule-Thomson expansion, and helium has a critical temperature at which the temperature does not drop even if Joule-Thomson expansion occurs due to its material properties. This critical temperature is called the inversion temperature.

Therefore, the branching flow temperature must be equal to or lower than the inversion temperature, so that the purpose of the branch flow, that is, the cooling effect generated in the process of reducing the heat of compression and expanding the branch, can be utilized. It should be designed to allow branch flow below the inversion temperature.

On the other hand, it is not possible to make a cooler that completely recondenses evaporated helium gas using only helium under the influence of the reverse transition temperature. Therefore, this embodiment is configured such that the heat absorbed into the hot portion of the gas helium is absorbed in the hot portion by the liquid neon recondensation apparatus manufactured on the same principle as the liquid helium recondensation apparatus.

FIG. 5C is a schematic diagram illustrating a side configuration of one unit of the three-stage liquid neon recondensing apparatus. FIG.

When the gas neon to be cooled enters the apparatus (540), it flows outward in the radial direction of the rotation center (545) and is compressed by centrifugal force. At this time, since the heat of compression is generated, the counterflow heat exchanger 560 is installed to exchange heat with the colder gas neon 565 that is cooled and then returned to the initial state. The gas neon compressed by the centrifugal force expands while flowing inward in the radial direction of the rotation center (550).

In addition, for the purpose as described in the liquid helium recondensation apparatus described above, the liquid neon recondensation apparatus is also designed to have a branch flow 555. However, in the case of neon, since there is no material property of having a reverse transition temperature, it is not necessary to require branch flow below the reverse transition temperature like helium.

On the other hand, in the present embodiment, in order to lower the temperature to 4.2 K, which is the liquefaction temperature of helium, eight liquid helium recondensation apparatuses and three liquid neon recondensation apparatuses were provided.

In addition, in order to show the optimal cooling effect, the branch flow is designed to occur in the lowest temperature stage of the multi-stage compression process of helium and neon.

6A is a temperature-entropy graph (T-s diagram) of helium of the cooler according to the basic principle of the present embodiment. This will be described with reference to FIG. 3.

Processes 610 and 615 are mechanical compression processes, which occur at 315 of FIG. 3, and processes 615 to 630 are multistages of gas helium occurring at the eight stage liquid helium recondensing apparatus 305. Compression-expansion process. By this process, the temperature of helium continues to drop, and eventually the gaseous helium is liquefied because the liquid temperature of helium becomes 4.2 K or less.

On the other hand, the process 620 and 621 is a branch flow process for expanding thomson-which will diverge some of the multi-stage expanding gas helium. At this time, the temperature of the branch flow, that is, the temperature corresponding to the state (620) should be less than the reverse transition temperature of helium.

The liquefied helium enters the cooling zone and cools the system (Q _He ) and then returns to the initial state (610), where multiple stages in the counterflow heat exchanger of the eight stage liquid helium recondensing unit are used for efficient energy management. Compression-heat exchange with the expanding gas helium. In addition, the heat of compression (Q _Ne ) generated during the mechanical compression process of the gas helium (610-> 615) is introduced through the liquid neon heat exchanger (310) to the three-stage liquid neon recondensing device (325).

6B is a temperature-entropy graph (T-s diagram) for neon of the cooler according to the basic principle of the present embodiment. This will be described with reference to FIG. 3.

Processes 650 and 655 are mechanical compression processes, which occur at 335 in FIG. 3, and processes 655 to 670 are multi-stages of gas neon occurring in the three-stage liquid neon recondensing unit 325. Compression-expansion process. By this process, the temperature of neon continues to drop, and eventually, the temperature of neon becomes less than or equal to 31 K, and the gas neon is liquefied (670).

On the other hand, the processes 660 and 661 are branch flow processes for expanding Thomson-which will diverge some of the multi-stage expanding gas helium.

The liquefied neon absorbs compressed heat (Q _Ne ) from the high-temperature (32 K) gas helium through the liquid neon heat exchanger (310), and then returns to the initial state (650), for efficient energy management. Heat exchange with multistage compression-expanding gas neon in a counterflow heat exchanger of a three stage liquid neon recondensing unit. In addition, the compression heat (Q _N2 ) generated in the mechanical compression process of the gas neon (650-> 655) is discharged to the liquid nitrogen storage tank 340 through the liquid nitrogen heat exchanger (330).

The thermodynamic analysis when the system is an ideal system using the thermodynamic properties of helium and neon and the thermodynamic relationship of the recondensation process for the present embodiment is as follows.

In the interpretation of the present invention, assuming that there is no heat exchanger, the temperature and pressure of each stage of helium and neon can be obtained through calculation.

If the pressure in the recondensation system becomes too high or requires a large amount of mass flow, or to compare different thermodynamic conditions, vary the liquefaction rate in the final recondensation step for each step. In terms of temperature and pressure, the higher the liquefaction rate, the higher the pressure of the entire system, but the lower the liquefaction rate, the greater the mass flow rate.

In the case of thermodynamic analysis of a system equipped with a heat exchanger as in this embodiment, there must be a branching flow towards the cold section due to the lack of cooling capacity of the relatively cold gas flowing in the reverse direction. This makes the structure of the entire chiller more complicated, but even in this case it is possible to design a system that exhibits an optimum liquefaction rate.

In constructing the system as a whole, adjustable values are the radius of rotation of the system, the angular velocity, the liquefaction rate at each stage and the pressure of the heat exchange gas passages flowing into the hot zone.

In this embodiment, the radius of rotation was 0.5 m, the angular velocity was 3600 rpm, and it was assumed that the pressure of the gas passage flowing in the reverse direction was kept constant. In addition, in the case of the helium stage, the temperature of the recondensed liquid helium is 4.2 K because it is necessary to maintain the superconducting magnet or superconducting property in a stable manner, and the pressure here is determined to be 1 atm. This is because increasing the pressure raises the recondensation temperature, making it difficult to maintain 4.2 K.

In the case of neon pressure, the liquefaction rate of the helium stage recondensation point determines the temperature and pressure of the hottest portion of the helium stage, which directly affects the temperature of the liquid neon in the neon stage, thus optimizing the helium stage. After the decision was made.

The most important factors in the optimization were the mass flow rate at the hottest portion of helium and neon, the amount of heat released into liquid nitrogen, and the number of branch flows to the next stage of the cold portion.

In this embodiment, in order to increase the thermodynamic efficiency of the overall system, first, an optimized system for the helium stage was first configured because the efficiency at the helium stage must be high. As a result of analyzing each case by changing the liquefaction rate from 0.1 to 1 in 0.1 units, the most efficient result was obtained when the liquefaction rate in the recondensation step was 0.8.

When a cooling load of 1 W was required at 4.2 K, the optimized helium stage consisted of eight isothermal compression and adiabatic expansion processes with a temperature of 32 K at the hottest part and a mass flow rate of 0.72 g / s.

The next step was to find an optimized neon step for this. In the case of neon, the critical pressure is 26.2 atm, which is considerably larger than 2.26 atm of helium, so when the pressure in the reverse gas passage is 1 atm, it expands and recondenses in the last stage except when the liquefaction rate is 0.1. It's already in the saturation region before it goes.

Therefore, when the pressure of the reverse gas passage is 1 atm, it is not significant to change the liquefaction rate except in the case of 0.1, so the liquefaction temperature of neon is set to 28 K, 29 K, 30 K, 31 K. By changing the corresponding saturation pressure 1.3 atm, 1.7 atm, 2.2 atm, 2.8 atm were analyzed.

Optimizing in this way, the pressure in the reverse gas passage is 2.8 atm for the neon stage. The neon stage consists of three stages, with the highest temperature at 79.7 K and a mass flow rate of 6.86 g / s.

For the helium and neon stages optimized in this example, the figure of merit (FOM) of the overall system was 0.105. In order to absorb 1 W of heat from the cryogenic part (4.2 K), it is necessary to transfer 98 W of heat to the liquid neon part, which in turn releases 171.8 W of heat to liquid nitrogen.

If anything is not considered in the present invention, it is the pressure loss that occurs as the fluid flows, which is negligible if the circulating mass flow rate is small, but when prototyped, the result is that the pressure loss of the system The thermodynamic state in each part may change slightly, so the optimization conditions of the present embodiment specified here will also be inevitable. However, the basic idea and thermodynamic analysis methodology presented in the present invention are not wrong and will be effective as a tool for optimizing the whole system.

Based on the above description, it can be seen from the present invention that a rotary cooler that does not require a continuous supply of liquid helium can be thermodynamically implemented, assuming an ideal state in constructing the cryogenic cooling system. Although realistic factors should be considered, including the Irresible Process, the device according to the invention does not require mass transfer between the site and the stationary site.

As described in detail above, the present invention simplifies the structure of the rotating cryogenic cooler, including the rotor of the superconducting generator, can reduce the manufacturing cost and the maintenance cost thereof, and also reduces the overall size of the cryogenic cooler. .

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only for describing the best embodiment of the present invention and not for limiting the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (7)

Rotation type including a compressor-expander using a property in which the refrigerant gas flows outward in the radial direction of the rotor and then expands inwardly in the radial direction of the rotor, and a counterflow heat exchanger in which the gases exchange heat with each other. In the chiller, The compression-expander comprises a multi-stage, rotary cooler characterized in that it is accompanied by a branching (Bleeding) to extract a portion of the refrigerant to perform a simple Joule-Thompson expansion. The method of claim 1, A rotary cooler comprising a plurality of cooling cells for forming a multi-fluid cycle using two or more kinds of fluids as respective refrigerants. The method of claim 2, Among the plurality of cooling cells, the first cooling cell which is in direct contact with the cooling part is helium as a refrigerant, and the branch flow in the first cooling cell is generated below the helium reverse transition temperature. . The method of claim 3, wherein And a second cooling cell that absorbs heat from the first cooling cell of which helium is a refrigerant among the plurality of cooling cells is neon. The method of claim 1, And a fin heat exchanger is installed to dissipate heat outside the rotary cooler. The method of claim 5, And a stationary cooling device outside the rotary cooler to extract heat from the fin heat exchanger. The method of claim 6, The stationary cooling device installed outside the rotary cooler comprises nitrogen as a refrigerant.