JP2010025411A - Heat exchanger and pulse tube refrigerating machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the capacity of a refrigerating machine by increasing pressure amplitude by reducing pressure loss in a boundary between a heat exchanger and a cold storage device and suppressing decline in a compression ratio. <P>SOLUTION: The heat exchanger is formed to have a columnar shape or cylindrical shape, and is provided with a plurality of through-holes formed on concentric circles on an end face of the column or cylinder and with grooves communicating the through-holes with each other at least on one face of the column or cylinder. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a heat exchanger that exchanges heat with a working gas, and a pulse tube refrigerator in which the heat exchanger is mounted.

A pulse tube refrigerator or the like is well known as a small cryogenic refrigerator that generates an extremely low temperature such as liquid nitrogen temperature.
FIG. 4 is a block diagram of a coaxial pulse tube refrigerator. The pulse tube refrigerator is composed of a compressor 1, a radiator 2, a regenerator 3, a cold head 4, a pulse tube 5 and a phase control mechanism 6. The principle of generating the refrigeration action is understood as follows. ing.

  The working gas (for example, helium gas) enclosed in the refrigerator is repeatedly compressed and expanded by the compressor 1 that reciprocates at a predetermined frequency. First, the working gas that has generated compression heat by the compression process of the compressor 1 releases the compression heat to the outside through the heat exchanger 21 in the radiator 2 (adiabatic compression process). The compressed working gas flows into the pulse tube 5 through the regenerator 3 and the cold head 4 (isothermal stroke). In the pulse tube 5, the working gas expands to generate cold (adiabatic expansion process). At this time, the phase of the working gas pressure and flow velocity is adjusted by the phase control mechanism 6. The phase control mechanism 6 includes an inertance tube 61 and a buffer tank 62, and the working gas flows therethrough with a substantially sinusoidal pressure amplitude. In the case of an electric circuit, the inertance tube 61 corresponds to an impedance component of inductance and resistance, and the buffer tank 62 corresponds to a capacitance component. Heat is absorbed from the cold head 4 by the cold generated as described above. Next, in the expansion process of the compressor 1, the working gas cooled by the pulse tube 5 returns to the compressor 1 through the radiator 2 while performing quasi-static heat exchange with the regenerator 3 (isothermal). Process). By repeating the above four steps, the cold head 4 is cooled to a very low temperature.

  In the prior art, the heat exchanger 21 of the radiator 2 used in such a refrigerator is a cylinder made of a material having a low thermal resistance such as copper as shown in FIGS. 5 (a) and 5 (b). The ring portion has a shape in which a large number of through holes 211 are provided in the axial direction. The cylindrical outer peripheral surface of the heat exchanger is integrally joined to the radiator 2 to constitute a heat dissipation path. On the other hand, a pulse tube is inserted into the inner peripheral surface of the cylinder, but it is better not to be thermally coupled, and there may be an appropriate clearance. One end of the cylindrical end surface is in contact with the space 22 coupled to the connecting pipe of the compressor, and the other end is in contact with the regenerator 3. It has a function of exchanging heat of the working gas flowing in from the compressor side on the surfaces of the many through holes 211 and radiating heat to the external space by the fins 23 provided in the radiator 2.

As a heat exchanger of this type of refrigerator, the one described in Patent Document 1 is well known.
JP 2002-257428 A

  In the conventional coaxial pulse tube refrigerator described above, the heat exchanger is provided with a large number of small-diameter through holes 211 in a cylindrical copper block so that the pressure loss is small and the heat exchange surface area can be increased, so that the opening ratio is about 40%. Is generally adopted. On the other hand, the regenerator 3 is constructed by laminating a stainless steel mesh 31 or the like formed in a ring shape as a regenerator material so that the resistance in the flow direction of the working gas is large and the resistance in the direction perpendicular to the flow of the working gas is small. . Specifically, it is composed of 300 to 500 mesh and an aperture ratio of about 70 to 80%.

As shown in FIG. 6A and FIG. 6B, the through hole 211 of the heat exchanger at the contact portion between the heat exchanger 21 and the regenerator 3 is made of a stainless wire mesh 31 constituting the regenerator material of the regenerator. As a result, the actual aperture ratio is reduced to about 30%. For this reason, there is a problem that pressure loss increases, pressure amplitude contributing to generation of cryogenic temperature decreases, and efficiency decreases.
On the other hand, simply providing a certain gap between the heat exchanger 21 and the regenerator 3 to ensure the aperture ratio is also performed. However, in the case of this method, the space from the compressor 1 to the inlet of the regenerator 3 functions as a working gas compression space by the piston of the compressor 1, so that the working gas compression ratio decreases and the refrigerator There arises a problem that the ability (efficiency) decreases.

  Therefore, the present invention aims to improve the refrigeration function by reducing the pressure loss at the boundary between the heat exchanger and the regenerator, increasing the pressure amplitude, and suppressing the decrease in the compression ratio. .

In order to solve the above problems, the invention according to claim 1 is configured in a columnar shape or a cylindrical shape, provided with a plurality of through holes through which the working gas flows in the axial direction of the column or the cylinder, and at least one of the columns or the cylinder is provided. A groove for communicating a plurality of through-holes is provided on the end face.
The invention according to claim 2 is characterized in that, in the heat exchanger according to claim 1, a plurality of through holes are provided on a plurality of concentric circles.

According to a third aspect of the present invention, in the heat exchanger according to the first or second aspect, the groove is provided in a circular shape.
The invention according to claim 4 is the heat exchanger according to any one of claims 1 to 3, wherein the groove is a V-groove.
In the invention according to claim 5, the flow path is formed by the compressor, the regenerator, the low temperature end, the pulse tube, the high temperature end and the phase control unit, and the cold is generated at the low temperature end by heat exchange of the working gas flowing through the flow path. In the pulse tube refrigerator, the heat exchanger according to any one of claims 1 to 4 is disposed so that an end surface having a groove is on a high temperature end side of the regenerator. refrigerator.

  According to this invention, even if the regenerator material of the regenerator is located in the axial direction of the through hole of the heat exchanger, the working gas flow path is ensured, so that a decrease in pressure amplitude due to working gas pressure loss is suppressed. This can improve the refrigeration capacity. On the other hand, it is possible to minimize the reduction in the refrigeration function due to the increase in the compression space. Furthermore, by using the V groove, the fluid resistance at the boundary between the heat exchanger and the regenerator can be reduced, thereby improving the heat exchange characteristics and reducing the fluid resistance loss.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, in this invention, since structures other than the heat exchanger 21 are the same structures as a prior art, description of parts other than a heat exchanger is abbreviate | omitted.
FIG. 1 is a diagram in which a heat exchanger according to the present invention is applied to a coaxial pulse tube refrigerator. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view. FIG. 2 is a detailed view of a portion D in FIG.

  The heat exchanger 21 is formed in a cylindrical shape with a material having high thermal conductivity such as copper. Further, a plurality of small through holes 211 are provided on a concentric circle whose center coincides with the axis of the cylinder. That is, it is formed so that the center of the through hole 211 is located on a concentric circle. Naturally, as shown to Fig.1 (a), the small through-hole 211 can be provided on several concentric circles. Thus, by providing the multiple through-holes 211, the aperture ratio of the heat exchanger is improved and the surface area for heat exchange is increased.

  Furthermore, a V groove 212 is formed on at least one end face of the cylinder of the heat exchanger 21 so as to coincide with a concentric circle provided with a through hole 211. Specifically, as shown in FIGS. 1 and 2, multiple V grooves 212 may be formed so that the tip of the V-shaped recess coincides with the center of the through hole. Further, the groove only needs to communicate with a part of the through hole 211, and the center of the through hole and the center of the groove do not necessarily coincide with each other.

  FIG. 3 is an enlarged view of a part of the heat exchanger. FIG. 3A is an enlarged plan view, and FIG. 3B is a cross-sectional view thereof. Even when the stainless wire mesh 31 that is a regenerator material of the regenerator is located above the through hole 211 of the heat exchanger as shown in the EE cross-sectional view of FIG. 3B, the plan view of FIG. As shown, the working gas diffuses in the groove direction by the V groove 212. Therefore, the pressure loss at the interface with the regenerator can be significantly reduced as compared with the conventional heat exchanger shown in FIG.

Furthermore, since the V-groove can be processed at the required depth and width, it is possible to minimize the expansion of the compression space for the working gas, and the space is simply at the boundary between the heat exchanger and the regenerator. Compared with the provision of refrigeration, it is possible to suppress a reduction in refrigeration capacity due to a decrease in compression ratio.
In addition, by forming the V groove, the shape factor of the end portion of the through hole is improved, so that the pressure loss as the whole heat exchanger is reduced and the efficiency of the refrigerator is improved.

The groove is not limited to the V-groove shape, and may be a groove having various cross-sectional shapes such as a semicircular shape and a square shape. Moreover, the through-hole 211 may be radially arranged in the center of the circle of the heat exchanger 21, and the groove may be formed on the radiation.
In this embodiment, the groove is provided only on the regenerator side, but of course, the groove may also be provided on the space 22 side.

  The above description is based on the coaxial pulse tube refrigerator and its heat exchanger. However, the present invention is not limited to the coaxial pulse tube refrigerator and its heat exchanger, but a U-shaped return type pulse tube refrigerator and a series type. Of course, the present invention can also be applied to a pulse tube refrigerator by making the heat exchanger cylindrical.

It is a figure at the time of applying the heat exchanger which concerns on this invention to a coaxial type pulse tube refrigerator. It is an enlarged view of the D section shown in FIG. It is the figure which showed the positional relationship of the heat exchanger which concerns on this invention, and the wire mesh which is a cool storage material of a cool storage. It is a block diagram of a coaxial pulse tube refrigerator. It is a figure of the conventional heat exchanger. It is the figure which showed the positional relationship of the conventional heat exchanger and the wire mesh which is a cool storage material of a cool storage.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compressor 2 Radiator 21 Heat exchanger 211 Through-hole 212 V groove 3 Regenerator 31 Wire net 4 Cold head 5 Pulse tube 6 Phase control part

Claims (5)

Consists of a cylindrical or cylindrical shape,
Providing a plurality of through holes that allow the working gas to flow in the axial direction of the cylinder or cylinder,
Providing a groove for communicating with a plurality of through holes on at least one end face of a column or cylinder;
A heat exchanger characterized by   The heat exchanger according to claim 1, wherein a plurality of through holes are provided on a plurality of concentric circles.   The heat exchanger according to claim 1 or 2, wherein the groove is provided in a circular shape.   4. The heat exchanger according to claim 1, wherein the groove is a V groove. In a pulse tube refrigerator that forms a flow path by a compressor, a regenerator, a low temperature end, a pulse tube, a high temperature end and a phase control unit, and generates cold at the low temperature end by heat exchange of the working gas flowing through the flow path,
A pulse tube refrigerator, wherein the heat exchanger according to any one of claims 1 to 4 is disposed such that an end surface having a groove is on a high temperature end side of the regenerator.

Images