JPH0650618A - Cryogenic freezer - Google Patents

Abstract

PURPOSE:To increase the efficiency of heat transfer between a small heat transfer pipe formed of a capillary tube and high-pressure helium gas flowing through the heat transfer pipe, in a J-T heat exchanger of a very low temperature freezer comprising a J-T freezer. CONSTITUTION:A turbulence promoting body 31 to promote turbulence of helium gas is arranged at the interior of a heat transfer pipe 24 in a state to be adhered on the inner surface of the heat transfer pipe 24. The increase of incurring of a pressure loss on a whole is suppressed in a way that the turbulence promoting body 31 is arranged in a manner to be limited to a part on the low temperature side where incurring of a pressure loss is decreased as seen from the whole of heat exchangers 13-15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cryogenic refrigerator that produces cryogenic levels of refrigeration by adiabatic expansion of compressed refrigerant gas such as helium, and more particularly to high pressure refrigerant gas from the compressor. The present invention relates to improvement of a heat exchanger that is cooled by exchanging heat with a low-pressure low-temperature refrigerant gas.

[0002]

2. Description of the Related Art Conventionally, for example, US Pat. No. 422 has been used as a cryogenic refrigerator for cooling a low temperature operating device operated at a cryogenic level of about 4K to the same temperature level.
As described in No. 3540, a pre-cooling refrigerator and a J-
A refrigerator combined with a T refrigerator is known.

The above-mentioned pre-cooling refrigerator comprises a refrigerator such as a GM cycle (Gifford-McMahon cycle) or an improved Solvay cycle. Helium gas (refrigerant gas) compressed by a compressor is adiabatically expanded by an expander, and the gas Cryogenic cold is generated in the heat station by the temperature drop.

On the other hand, the JT refrigerator has a precooler for precooling by exchanging heat between the helium gas supplied from the compressor and the heat station of the expander in the precooling refrigerator, and the helium gas by Joule Thomson. Inflating JT
A valve is connected to a closed circuit to provide a JT circuit. In this JT circuit, the helium gas from the compressor is precooled by a precooler, and the precooled helium gas is cooled by the JT circuit. -The T-valve is used to expand Joule Thomson to generate 4K level cold.

By the way, the above J-T refrigerator is equipped with a plurality of stages of heat exchangers called J-T heat exchangers in its circuit. In each heat exchanger, the primary side and the secondary side are respectively provided. Heat is exchanged between the passing helium gases. That is, for example, a heat transfer tube (high-pressure tube) is spirally arranged between inner and outer cylindrical shells that are joined concentrically, and the inside of the heat transfer tube is
While forming in the high-pressure gas flow path (primary side) through which the high-pressure refrigerant gas supplied from the compressor to the expander flows, low-pressure gas returning from the expander to the compressor flows through the space between the shells around the heat transfer tube. The low-pressure gas channel (secondary side) is used, and the gas in the high-pressure gas channel that flows from the compressor to the expander exchanges heat with the low-temperature gas in the low-pressure gas channel that returns from the expander to the compressor. I am trying to cool it.

[0006]

The heat transfer tube of the JT heat exchanger is generally made of copper. To further improve the heat exchange performance of the heat exchanger, the inside of the heat transfer tube is to be improved. It is necessary to perform processing to accelerate heat transfer.

However, the heat transfer tube is usually a very thin capillary tube having an outer diameter of 3 mm and an inner diameter of about 2 mm, and the inner diameter is extremely small, so that it is actually difficult to process the inside thereof.

The present invention has been made in view of the above problems, and an object of the present invention is to insert a predetermined structure into the heat transfer tube so that even if the capillary tube is a thin capillary tube, the refrigerant inside the tube is reduced. The purpose is to increase the efficiency of heat transfer with gas.

[0009]

In order to achieve the above object, in the invention of claim 1, a turbulent flow promoting body for promoting the turbulent flow of the refrigerant gas is arranged inside the heat transfer tube.

That is, according to the present invention, as shown in FIGS. 1 to 5, a compressor for compressing a refrigerant gas and a high-pressure refrigerant gas discharged from the compressor are expanded to generate cryogenic cold. An expansion means (18), and
Inside the heat transfer tube (24), the expansion means (1
High pressure gas flow path (2) through which high pressure refrigerant gas supplied to
5) is formed, a low pressure gas flow path (26) for flowing low pressure gas returning from the expansion means (18) to the compressor is formed around the heat transfer tube (24), and the high pressure gas flow path (25) is formed. )
It is premised on a cryogenic refrigerator provided with heat exchangers (13) to (15) for exchanging heat with the low-temperature gas in the low-pressure gas flow path (26) to cool the gas therein.

Inside the heat transfer tube (24), there is provided a turbulent flow promoting body (31) which is in close contact with the inner surface of the heat transfer tube (24) and promotes the turbulent flow of the refrigerant gas in the high pressure gas passage (25). .

In the inventions of claims 2 to 11, the specific structure of the turbulent flow promoting body (31) in the heat exchangers (13) to (15) is specified. That is, in the invention of claim 2, as shown in FIG. 4 (a), the turbulence promoting body (31) has at least one pair of circular cross-sections extending in the heat transfer tube length direction in the heat transfer tube (24). The thin tubes (32), (32), ... Are inserted in a press-fit state such that each pair of thin tubes (32) are aligned substantially parallel to one diametrical direction of the heat transfer tube (24).
Further, in the invention of claim 3, as shown in FIG. 1, at least two pairs of similar thin tubes (32), (32), ... having a circular cross section are provided, and a pair of thin tubes adjacent to each other in the length direction of the heat transfer tube. (3
2) and (32) are arranged so that the parallel directions of them are displaced from each other in the circumferential direction of the heat transfer tube.

According to the fourth aspect of the present invention, as shown in FIG. 4 (b), the turbulent flow promoting body (31) has at least one pair of sectional half circles extending in the heat transfer tube length direction within the heat transfer tube (24). Shaped thin tubes (32), (32), ... Are each pair of thin tubes (32), (3
2) It is assumed that the heat transfer tubes (24) are fitted into each other in a press-fit state such that they are in contact with each other on a half-divided surface and arranged substantially parallel to one diametrical direction of the heat transfer tube (24).

In the fifth aspect of the invention, as shown in FIG. 4 (c), the turbulent flow promoting body (31) has at least one triangular cross section extending in the heat transfer tube length direction in the heat transfer tube (24). The thin tube (32) of the three corners (32a), (32a),
... are inserted in a press-fitted state so that they come into contact with the inner surface of the heat transfer tube (24). In the invention of claim 6, in FIG.
As shown in (d), the thin tube (32) having the triangular cross section.
And a plurality of thin tubes (3
2) The corner portions (32a) and (32a) of the (32) are arranged so that the positions thereof are displaced from each other in the circumferential direction of the heat transfer tube.

In the invention of claim 7, as shown in FIG. 4 (e), the turbulence promoting body (31) has at least one elliptical cross section extending in the heat transfer tube length direction in the heat transfer tube (24). The thin tube (32) is provided with its longitudinal ends (32b) and (32b).
Are inserted in a press-fitted state so as to contact the inner surface of the heat transfer tube (24). Further, in the invention of claim 8, in FIG.
As shown in (f), the thin tube (32) having the oval cross section.
And a plurality of thin tubes (3
2) and (32) are arranged such that the major axis directions of them are displaced from each other in the heat transfer tube circumferential direction.

According to the invention of claim 9, FIGS. 4 (g) to 4 (i) are used.
As shown in, the turbulence promoter (31) is connected to the heat transfer tube (24).
Inside the heat transfer tube (2
4) At least one plate member (35) having a shape radially extending from the central position of the plate member (35) is press-fitted so that the outer end of the plate member (35) contacts the inner surface of the heat transfer tube (24). Shall be.

In the tenth aspect of the invention, as shown in FIG. 5 (a), the turbulent flow promoting body (31) is composed of fins (33) projecting from the inner surface of the heat transfer tube (24). Further, in the invention of claim 11, as shown in FIG. 5 (b), a turbulent flow promoting body (31) is spirally filled in the heat transfer tube (24) so as to be in close contact with the inner surface of the heat transfer tube (24). The wire (34).

According to the twelfth aspect of the present invention, the turbulent flow promoting body (31) having each of the above configurations is arranged at the low temperature side portion of the heat transfer tube (24) in the entire heat exchangers (13) to (15).

[0019]

With the above structure, in the invention of claim 1, the turbulent flow promoting body (31) for the refrigerant gas is provided inside the heat transfer tubes (24) in the heat exchangers (13) to (15).
The turbulence promoting body (31) can promote the turbulence of the flow of the high-pressure gas in the high-pressure gas channel (25). Moreover, the cross-sectional area of the high-pressure gas channel (25) is reduced by the cross-sectional integration of the turbulence promoter (31), the flow velocity of the high-pressure gas can be increased, and the inner surface of the heat transfer tube (24) of the turbulence promoter (31) can be increased. Due to the close contact with the turbulent flow promoting body (31) itself, heat can be transferred to increase the entire heat transfer area. With these, even if the heat transfer tube (24) is composed of a small-diameter capillary tube, the heat transfer efficiency with the high-pressure refrigerant gas therein can be increased, and the heat exchangers (13) to (1).
The heat exchange performance of 5) can be improved.

According to the inventions of claims 2 to 11, the turbulent flow promoting body (31) suitable for the case where the heat transfer tube (24) is a capillary tube having a small diameter can be easily obtained. In particular, in the invention of claim 3, 6 or 8, adjacent thin tubes (3) are arranged in the parallel direction of adjacent pairs of thin tubes (32), (32).
2), each corner position of (32), or the long axis direction of the adjacent thin tubes (32), (32) are mutually heat transfer tubes (2
Since they are arranged so as to be displaced in the circumferential direction of 4), the boundary layer of the gas is renewed at this displaced portion, and the promotion of heat transfer can be further improved.

On the other hand, due to the arrangement of the turbulence promoting body (31) in the heat transfer tube (24), there is a concern that the pressure loss may increase. However, this pressure loss changes in proportion to the temperature. , The lower the temperature, the lower. In the invention of claim 12, the turbulent flow promoting body (31) includes the heat exchangers (13) to (1).
5) The heat exchangers (13) to (1) are well-balanced because they are arranged only in the low temperature side portion where the pressure loss is small as a whole, and the influence of the increase in the pressure loss as a whole is small.
5) is obtained.

[0022]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, as shown in FIG. 3, the refrigerator (R) is composed of a refrigerator in which a pre-cooling refrigerator (1) and a JT refrigerator (11) are combined.

The precooling refrigerator (1) is composed of a GM (Gifford-McMahon) cycle refrigerator, and is used to precool the helium gas (refrigerant gas) in the JT refrigerator (11). Helium gas is compressed and expanded. This refrigerator (1) comprises a pre-cooling compressor (not shown) and an expander (2) attached to a cryostat (C) connected in a closed circuit. The expander (2) includes a closed cylindrical case (3) arranged outside the cryostat (C), and a two-stage structure cylinder (4) connected to the lower part of the case (3). Have. The case (3) has a high pressure gas inlet (5) connected to the discharge side of the precooling compressor and a low pressure gas outlet (6) connected to the suction side thereof. Further, the cylinder (4) penetrates the upper wall of the cryostat (C) and extends inside thereof, and the lower end of the large diameter portion (4a) thereof is maintained at a predetermined temperature level in the first heat station (7). ), And the lower end of the small diameter portion (4b) is the first heat station (7).
The second heat station (8) is maintained at a lower temperature level.

That is, although not shown here, in the cylinder (4), a displacer (replacement) for partitioning and forming an expansion space at a position corresponding to each of the heat stations (7) and (8) in the cylinder (4) is formed. Container) is reciprocatingly inserted. On the other hand, in the case (3), a rotary valve that opens and closes each time it rotates and a valve motor that drives the rotary valve are housed. The rotary valve supplies the helium gas flowing from the high pressure gas inlet (5) to the expansion space in the cylinder (4) or discharges the helium gas expanded in the expansion space from the low pressure gas outlet (6). Switch to. Then, by opening the rotary valve in the expander (2), the high-pressure helium gas is expanded in the expansion space in the cylinder (4) by Simon, and the temperature drop due to the expansion causes a cryogenic level of coldness. Cold is held at the first and second heat stations (7), (8) in the cylinder (4). That is, in the pre-cooling refrigerator (1), high-pressure helium gas discharged from the compressor is supplied to the expander (2),
The temperature of the heat stations (7) and (8) is lowered by the adiabatic expansion in the expander (2) to precool later-described precoolers (16) and (17) in the JT refrigerator (11). At the same time, the expanded low pressure helium gas is returned to the compressor and recompressed. The first heat station (7) of the cylinder (4) supports a radiation shield (S) having a substantially closed cylindrical shape arranged in the cryostat (C) so that heat can be transferred.

On the other hand, the JT refrigerator (11) has about 4
A refrigerator for compressing helium gas to expand Joule-Thomson to generate K-level cold, and a JT compressor (not shown) for compressing helium gas, and the compressed helium gas are used as joules. And an expander (12) for expanding the Thomson. The expander (12) is located in the radiation shield (S) of the cryostat (C) and is the first to third JT heat exchangers (13) to (1).
5) is provided. Each J-T heat exchanger (13)
(15) is a primary side (high pressure gas flow path (25) in a heat transfer tube (24) described later) and a secondary side (similar low pressure gas flow path (2)
6)) are mutually heat-exchanged between the helium gases passing through, and the primary side of the first JT heat exchanger (13) is connected to the discharge side of the JT compressor. Also, the first
And the primary sides of the second JT heat exchangers (13) and (14) are adsorbers (20) for removing contamination.
a) and the expander (2) in the pre-cooling refrigerator (1)
Are connected via a first precooler (16) arranged on the outer periphery of the first heat station (7). Similarly, the primary sides of the second and third J-T heat exchangers (14), (15) are arranged on the adsorber (20b) and the outer periphery of the second heat station (8) of the expander (2). Second precooler (17)
Connected through. Further, the primary side of the third JT heat exchanger (15) is connected to an adsorber (20c) and a cooler (19) via a JT valve (18) for Joule-Thomson expansion of high-pressure helium gas. For example, the object to be cooled is connected to the cooler (19) via a heat transfer member (not shown) such as a copper mesh wire so that heat can be transferred. The opening of the JT valve (18) is adjusted from outside the cryostat (C) by the operation rod (18a). The cooler (19) includes the third and second J-Ts.
After passing through the secondary sides of the heat exchangers (15) and (14), the first J-
The first J-T is connected to the secondary side of the T heat exchanger (13).
The secondary side of the heat exchanger (13) is connected to the suction side of the JT compressor.

Therefore, in the J-T refrigerator (11), the J-
The helium gas is compressed to a high pressure by the T compressor and is supplied to the expander (12), which is then supplied to the first to third JT heat exchangers (13) to (15) of the expander (12). , Heat exchange with low-temperature low-pressure helium gas returning to the compressor side, and at the first and second precoolers (16) and (17), the first and second heat stations (7) of the expander (2), After cooling in (8), Joule-Thomson expansion is performed in the JT valve (18), and 1 atmosphere in the cooler (19), about 4
The helium in the gas-liquid mixed state of K is used, and the cooler (19) is brought to a cryogenic level (about 4K) by the latent heat of vaporization of this helium.
Cool to. Thereafter, the helium gas, which has been reduced in pressure by the expansion, is passed through the first to third J-T heat exchangers (13) to
It is configured such that it is sucked into the JT compressor and recompressed through each secondary side of (15).

First to third J-T heat exchangers (13)-
(15) has the same structure, and as shown in FIG. 2, for example, the inner and outer cylindrical shells (2
In the space between 1) and (22), a heat transfer tube (24) (high pressure tube) having a fin (23) attached to the outer periphery is spirally wound and housed. The heat transfer tube (24) is a heat transfer tube (24) having a predetermined length, for example, by connecting capillary tubes having a length of 2 m in series. The internal space of the heat transfer tube (24) is connected to the JT valve (1) of the compressor to the expander (13).
8) or formed in the high pressure gas flow path (25) (primary side) through which the high pressure helium gas supplied to the cooler (19) flows,
Meanwhile, the inner and outer shells (21) around the heat transfer tube (24),
The space between (22) is provided in the low pressure gas flow path (26) (secondary side) through which the low pressure gas returning from the JT valve (18) or the cooler (19) to the compressor flows, and To J-
The low-pressure gas passage (the low-pressure gas passage (25) for returning the gas in the high-pressure gas passage (25) flowing toward the T valve (18) or the cooler (19) from the J-T valve (18) or the cooler (19) to the compressor. Two
6) It is cooled by heat exchange with the low temperature gas inside. Then, in the first J-T heat exchanger (13), high-pressure helium gas is heated from room temperature to 50 K, in the second J-T heat exchanger (14), helium gas is heated from 50 K to 15 K, and further in the third J-T heat exchange. In the vessel (15), add 1 helium gas
Each is cooled from 5K to about 5K.
In FIG. 2, (27) is glass wool contained in the inner shell (21).

As a feature of the present invention, when the first to third three JT heat exchangers (13) to (15) are considered to be one heat exchanger, the low temperature side of the whole heat exchanger is considered. The first J-T portion, specifically, a portion of 100K or less, for example.
Primary side low temperature end of heat exchanger (13) and second and third J
Inside the heat transfer tubes (24) in the entire primary side of the -T heat exchangers (14) and (15), as shown in FIG. 1, turbulent flow promotion for promoting turbulent flow of high-pressure helium gas. Body (3
1) is filled. When a plurality of capillary tubes are joined to form a heat transfer tube (24) having a predetermined length, the turbulent flow promoting body (31) has a capillary tube, that is, a heat transfer tube (2) in each capillary tube before the joining.
4) at least two pairs of thin tubes (32), (32) having a circular cross section, which extend in the lengthwise direction, are fitted in from both sides of the capillary tube in a press-fitted state, and each pair of thin tubes (32), The pair of thin tubes (32) arranged adjacent to each other in the diametrical direction of the heat transfer tube (24) and adjacent to each other in the longitudinal direction of the heat transfer tube (24) are transferred to each other in the parallel direction. The heat pipe (24) is fitted and inserted so as to be displaced by a predetermined angle θ (θ = 90 ° in the illustrated example) in the circumferential direction.

Next, the operation of the above embodiment will be described. When the refrigerator (R) is in a steady operation state, in the pre-cooling refrigerator (1), the high-pressure helium gas supplied from the pre-cooling compressor is expanded in the expander (2), and the temperature drop due to the expansion of this gas. This cools the first heat station (7) of the cylinder (4) to a temperature level of 55 to 60K and the second heat station (8) to a temperature level of 15 to 20K. The first heat station (7)
The temperature of the radiation shield (S) contacting the heat station (7) so as to be able to transfer heat drops to the same temperature level as that of the first heat station (7) as a result of the cooling of the heat station (7), which causes the cryostat (C). Radiation shield is applied to the center of the inside from the outside.

On the other hand, at the same time, the JT refrigerator (1
In 1), the high-pressure helium gas discharged from the compressor enters the primary side of the first JT heat exchanger (13) and is heat-exchanged with the secondary low-pressure helium gas returning to the compressor side. The temperature is cooled from 300 K to about 50 K at room temperature, and then, the first precooler (16) around the first heat station (7) of the expander (2) is further cooled. This cooled gas enters the primary side of the second J-T heat exchanger (14) and is cooled to about 15 K by heat exchange with the low pressure helium gas on the secondary side, and then expanded (2 The second precooler (17) around the second heat station (8) is further cooled. After this, the gas enters the primary side of the third J-T heat exchanger (15) and is cooled to about 5K by heat exchange with the low-pressure helium gas on the secondary side, and then J-
To the T valve (18). In this JT valve (18), the high-pressure helium gas is throttled and expanded by Joule-Thomson to become helium in a gas-liquid mixed state of 1 atm and about 4 K, and is supplied to the cooler (19). Then, in this cooler (19), the cooling target is cooled to an extremely low temperature of 4K level by the latent heat of vaporization of the liquid portion in the helium in the gas-liquid mixed state.

In this embodiment, the turbulent flow promoting body (31) for helium gas is filled in the heat transfer tubes (24) at predetermined portions of the first to third JT heat exchangers (13) to (15). Therefore, due to the turbulence promoter (31), the turbulence of the flow of the high-pressure helium gas in the high-pressure gas passage (25) from the compressor to the JT valve (18) or the cooler (19) is disturbed. Be promoted. At that time, the turbulence promoter (31)
Is formed by inserting two pairs of thin tubes (32), (32) having a circular cross-section into each capillary tube constituting the heat transfer tube (24) in a press-fitted state from both sides of the tube. (32), a pair of thin tubes (32) arranged parallel to each other in the diametrical direction of the heat transfer tube (24) and adjacent to each other in the length direction of the heat transfer tube (24) Since the directions are fitted so as to be offset from each other by a predetermined angle in the circumferential direction of the heat transfer tube, each pair of adjacent thin tubes (32), (3
2) The boundary layer of the gas is renewed at the misaligned portions, and the turbulence of the gas can be further promoted. Further, in the high-pressure gas passage (25) in the heat transfer tube (24), since the cross-sectional area of the high-pressure gas passage (25) is reduced by the cross-sectional integration of the filled turbulence promoter (31), the high-pressure gas passage (25) The flow velocity of increases. further,
Since each thin tube (32) of the turbulence promoting body (31) is in close contact with the inner surface of the heat transfer tube (24) at a part of the outer circumference, heat conduction can be performed via each thin tube (32). The area can be increased as a whole. By these synergistic actions, even if the heat transfer tube (24) is composed of a small-diameter capillary tube, the heat transfer efficiency with the high-pressure helium gas therein can be increased, and the heat exchanger (13)- (1
The heat exchange performance of 5) can be improved.

The turbulent flow promoting body (31) is composed of
The first J-T heat exchanger (13) is a low temperature side portion of the entire heat exchanger including the three third J-T heat exchangers (13) to (15), that is, a portion having a temperature of 100 K or less, for example. Primary side cold end and second and third J-T heat exchangers (1
4) and (15) are arranged only on the primary side as a whole, and the pressure loss at the arranged portion is originally small, so that the influence of the increase in the pressure loss as a whole is small and a well-balanced heat exchanger ( 13) to (15) are obtained.

(Modification of Turbulent Flow Promoter) The turbulent flow promoter (31) may have various configurations other than the above embodiment, but the heat transfer tube (24) is formed of a capillary tube having a small diameter. However, its structure is limited. As the turbulent flow promoting body (31) which can be easily filled in the small diameter heat transfer tube (24), the one shown in FIG. 4 or 5 is preferable.

That is, in the example shown in FIG. 4 (a), the turbulent flow promoting body (31) has two pairs of thin tubes (32), (32), ... The pair of thin tubes (32) and (32) are inserted so that the parallel directions are the same.

Further, in the example shown in FIG. 4 (b), the thin tube (32) extending in the length direction of the heat transfer tube (24) has a semicircular cross section, and this pair of thin tubes having a semicircular cross section. (3
2) and (32) are each a pair of thin tubes (3) in the heat transfer tube (24).
2) and (32) are in contact with each other on a half-divided surface and the heat transfer tube (24)
Is inserted in a press-fitted state so as to be aligned substantially parallel to one diametrical direction.

In the example shown in FIG. 4 (c), the heat transfer tube (24)
At least one thin tube (32) extending in the longitudinal direction of the tube has a triangular cross section, and the thin tube (32) is a heat transfer tube (24).
The three corners (32a), (32a), ... Are inserted into the inside of the heat transfer tube (24) in a press-fitted state so as to come into contact with the inner surface. At this time, as shown in FIG.
A plurality of rectangular thin tubes (32) are provided, and the plurality of thin tubes (32), (3) having a triangular cross section are formed in the same manner as in the above embodiment.
2), ... Inside the heat transfer tube (24), the positions of the corner portions (32a), (32a) of the thin tubes (32), (32) adjacent to each other in the length direction of the heat transfer tube (24) are mutually predetermined. You may insert so that it may shift | deviate only by the angle (theta) (theta = 60 degrees in the example of illustration).

In the example shown in FIG. 4 (e), the thin tube (32) has an oval cross section, and the thin tube (32) has an oval cross section.
In the heat transfer tube (24), both ends (32b), (32b) of the thin tube (32) in the long axis direction are press-fitted so as to contact the inner surface of the heat transfer tube (24). Also, at this time,
As shown in FIG. 4 (f), the thin tube (3
2) and a plurality of thin tubes (3
2), (32), ..., The long axis directions of the thin tubes (32), (32) adjacent to each other in the length direction of the heat transfer tube have a predetermined angle θ.
They are arranged so as to deviate by (θ = 90 ° in the illustrated example).

In the turbulent flow promoting body (31) of the example shown in FIGS. 4 (g) to (i), the heat transfer tube (2) is used instead of the thin tube (32).
4) at least one plate member (35) having a cross-sectional shape that extends radially from the center of the heat transfer tube (24) in the radial direction is used.
Is inserted into the heat transfer tube (24) in a press-fitted state so that the outer end of the plate (35) contacts the inner surface of the heat transfer tube (24). Specifically, the turbulent flow promoting body (3
In 1), a plate material (35) having a cross-shaped cross section is used. At that time, as shown in FIG. 4 (h), a bent portion (35a) may be formed at the outer end of the plate material (35) so that the contact area with the inner surface of the heat transfer tube (24) increases. Further, the turbulent flow promoting body (31) of FIG. 4 (i) uses a plate material (35) having a substantially Y-shaped cross section.

Furthermore, the turbulence promoting body (3) shown in FIG.
1) is composed of fins (33) spirally protrudingly provided on the inner surface of the heat transfer tube (24). Further, the turbulent flow promoting body (31) shown in FIG. 5 (b) is installed in the heat transfer tube (24).
4) Spiral wire (3) packed so as to closely adhere to the inner surface
4).

Therefore, these turbulence promoters (31)
However, the same effect as that of the above embodiment can be obtained.

[0041]

As described above, according to the invention of claim 1, the turbulent flow promoting body is provided by providing the turbulent flow promoting body for the refrigerant gas inside the heat transfer tube of the heat exchanger in the cryogenic refrigerator. Turbulence of the flow of high-pressure gas in the high-pressure gas channel is promoted, and the cross-sectional area of the high-pressure gas channel is reduced by the cross-sectional integral of the turbulence promoting body to increase the flow velocity of high-pressure gas, and further turbulence promotion Adhesion of the body to the inner surface of the heat transfer tube can increase the overall heat transfer area, and even if the heat transfer tube is a capillary tube with a small diameter, it increases the heat transfer efficiency with the high pressure refrigerant gas inside it, The heat exchange performance of the exchanger can be improved.

According to the inventions of claims 2 to 11, a turbulent flow promoting body suitable for a case where the heat transfer tube is a small diameter capillary tube can be easily obtained. In particular, according to the invention of claim 3, 6 or 8, the parallel direction of the adjacent thin tubes, the respective corner positions of the adjacent thin tubes, or the long axis direction of the adjacent thin tubes are displaced from each other. Since it is arranged, the boundary layer of the gas can be renewed at this misaligned portion, and the promotion of heat transfer can be further improved.

According to the twelfth aspect of the invention, since the turbulence promoting body is arranged only in the low temperature side portion where the pressure loss is small when viewed from the entire heat exchanger, the increase of the pressure loss as a whole can be suppressed, A well-balanced heat exchanger can be obtained.

[Brief description of drawings]

FIG. 1 is an enlarged cross-sectional view of a heat transfer tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a part of a JT heat exchanger.

FIG. 3 is a refrigerant circuit diagram showing the overall configuration of a cryogenic refrigerator.

FIG. 4 is a view corresponding to FIG. 1 showing a modified example of the turbulent flow promoting body.

FIG. 5 is a cross-sectional view schematically showing another modification of the turbulent flow promoting body.

[Explanation of symbols]

 (R) Cryogenic refrigerator (1) Precooling refrigerator (11) JT refrigerator (12) Expander (13)-(15) JT heat exchanger (18) JT valve (expansion means) (24) Heat transfer tube (25) High pressure gas flow path (26) Low pressure gas flow path (31) Turbulence promoter (32) Capillary tube (32a) Corner (32b) Long axis direction end (33) Fin (34) Wire (35) Plate material

Claims (12)

[Claims] 1. A compressor for compressing a refrigerant gas, an expansion means (18) for expanding a high-pressure refrigerant gas discharged from the compressor to generate a cryogenic level of cold, and a heat transfer tube (24) inside the heat transfer tube (24). , Expansion means (1
High pressure gas flow path (2) through which high pressure refrigerant gas supplied to
5) is formed, a low pressure gas flow path (26) for flowing low pressure gas returning from the expansion means (18) to the compressor is formed around the heat transfer tube (24), and the high pressure gas flow path (25) is formed. )
A cryogenic refrigerator comprising: heat exchangers (13) to (15) for cooling the internal gas by exchanging heat with a low temperature gas in a low pressure gas flow path (26), ), There is provided a turbulent flow promoting body (31) which is in close contact with the inner surface of the heat transfer tube (24) and promotes the turbulent flow of the refrigerant gas in the high pressure gas flow channel (25). . 2. The cryogenic refrigerator according to claim 1, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) is
Within the heat transfer tube (24), at least one pair of thin tubes (32), (32), ... each having a circular cross section, extending in the length direction of the heat transfer tube, each pair of thin tubes (32), (32) are heat transfer tubes (24). ), The cryogenic refrigerator characterized by being fitted and inserted in a press-fitted state so as to be arranged substantially parallel to one diametrical direction. 3. The cryogenic refrigerator according to claim 2, wherein the turbulence promoting body (31) of the heat exchangers (13) to (15) is
Comprising at least two pairs of thin tubes (32), (32), having a circular cross section, which are fitted into the heat transfer tube (24), and a pair of thin tubes (32), (32) adjacent to each other in the length direction of the heat transfer tube.
A cryogenic refrigerator, wherein the parallel directions of the two are arranged so as to be offset from each other in the circumferential direction of the heat transfer tube. 4. The cryogenic refrigerator according to claim 1, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) is
At least one pair of thin tubes (32), (32), ... each having a semi-circular cross section and extending in the lengthwise direction of the heat transfer tube, are halved in each pair of thin tubes (32), (32). A cryogenic refrigerator characterized in that the heat transfer tubes (24) are fitted and inserted in a press-fit state so as to be aligned substantially parallel to one diametrical direction of the heat transfer tubes (24). 5. The cryogenic refrigerator according to claim 1, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) is
At least one thin tube (32) having a triangular cross-section extending in the length direction of the heat transfer tube (24) has three corner portions (32a), (32a), ... Two
4) A cryogenic refrigerator characterized by being inserted in a press-fitted state so as to come into contact with the inner surface. 6. The cryogenic refrigerator according to claim 5, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) comprises:
Each of the thin tubes (32), (32) adjacent to each other in the length direction of the heat transfer tube is composed of a plurality of thin tubes (32), (32), ... A cryogenic refrigerator characterized in that the corners (32a), (32a) are arranged such that the positions thereof are displaced from each other in the circumferential direction of the heat transfer tube. 7. The cryogenic refrigerator according to claim 1, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) is
In the heat transfer tube (24), at least one thin tube (32) having an elliptical cross section extending in the length direction of the heat transfer tube is provided, and both ends (32b) and (32b) of the thin tube (32) in the long axis direction have the heat transfer tube (2).
4) A cryogenic refrigerator characterized by being inserted in a press-fitted state so as to come into contact with the inner surface. 8. The cryogenic refrigerator according to claim 7, wherein the turbulent flow promoting body (31) of the heat exchangers (13) to (15) comprises:
The thin tubes (32), (32), ... Having a plurality of elliptical cross-sections inserted into the heat transfer tubes (24), and the lengths of the thin tubes (32), (32) adjacent to each other in the length direction of the heat transfer tube. A cryogenic refrigerator characterized in that they are arranged such that their axial directions are offset from each other in the circumferential direction of the heat transfer tube. 9. The cryogenic refrigerator according to claim 1, wherein the turbulence promoting bodies (31) of the heat exchangers (13) to (15) are:
In the heat transfer tube (24), at least one plate member (35) extending in the length direction of the heat transfer tube and having a cross-sectional shape radially extending radially from the central position of the heat transfer tube (24) is provided. (4) is a cryogenic refrigerator characterized by being fitted and inserted in a press-fitted state so that the outer end portion thereof comes into contact with the inner surface of the heat transfer tube (24). 10. The cryogenic refrigerator according to claim 1, wherein the turbulent flow promoting body (31) is a fin (33) protruding from the inner surface of the heat transfer tube (24). Machine. 11. The cryogenic refrigerator according to claim 1, wherein the turbulence promoter (31) is attached to the heat transfer tube (24).
4) Spiral wire (3) packed so as to closely adhere to the inner surface
4) A cryogenic refrigerator characterized in that 12. The method according to claim 1, 2, 3, 4, 5, 6, 7,
In the cryogenic refrigerator of 8, 9, 10 or 11, the turbulence promoter (31) is arranged at the low temperature side portion of the heat transfer tube (24) in the entire heat exchangers (13) to (15). A characteristic cryogenic refrigerator.