JP2828948B2 - Regenerative heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas compression / expansion machine such as a Stirling engine used for generating power and a Stirling refrigerator used for generating low temperature, and more particularly to an improvement in heat exchange performance of a regenerative heat exchanger. Things.

[0002]

2. Description of the Related Art In recent years, there has been an urgent need to develop techniques for preserving various samples and various materials at extremely low temperatures in advanced technology fields such as the field of biotechnology and the field of electronic devices. In particular, gas compression / expansion machines such as Stirling refrigerators are attracting attention as means for achieving the extremely low temperature, and are going to be widely used for cooling, biomedical freezers, freezers, and the like for various infrared sensors, superconducting devices, and the like.

In this gas compression / expansion machine, a regenerative heat exchanger (regenerator) is provided in a working gas flow path between the expansion chamber and the compression chamber, and stores and radiates heat of the moving working gas. , A device for improving the capacity of a refrigeration system.

Hereinafter, a displacer type Stirling refrigerator having a regenerative heat exchanger disposed therein will be described.
This will be described in detail with reference to FIG. An expansion cylinder (2) and a compression cylinder (3) are attached to the main body housing (1) at an angle difference of 90 degrees, and a displacer (6) built in the expansion cylinder (2) and a compression cylinder (3) are attached. The built-in compression piston (7) is connected to a common crank mechanism (5) and is reciprocated in a state where the phases are shifted from each other.

As shown in FIG. 4, the displacer (6) is filled with a cold storage material (14) made of, for example, a sintered metal in a cylindrical body (17) having both ends opened (18, 19). The working gas G flowing from one opening (18) of the cylindrical body (17) passes through the inside of the cold storage material (14) and flows out of the other opening (19) in the process of flowing out of the cold storage material (1).
Heat exchange with 4) is performed.

The displacer (6) also has a function as a regenerative heat exchanger, and its heat exchange performance greatly affects the coefficient of performance of a Stirling refrigerator.

As shown in FIG. 3, the expansion cylinder (2) and the compression cylinder (3) are provided with oil seals (8) and (9), respectively.
Thus, the base end of the expansion cylinder (2) and the base end of the compression cylinder (3) are communicated with each other by a communication pipe (4).
Oil (10) is injected into the crank chamber (12).

FIG. 5 shows the operation of the above Stirling refrigerator with time T on the horizontal axis and stroke S on the vertical axis. In the Stirling refrigerator, the displacer (6) reciprocates as shown by curves B and C in FIG. 5, and the compression piston (7) reciprocates as shown by curve D in FIG. 5), the volume of the expansion space (11) changes in the width region between the straight line A and the curve B in FIG. 5, and the compression space (1) of the compression cylinder (3).
3) changes in volume in the width region between the curves C and D in FIG.

As a result, in the process of FIG. 5, the gas in the compression space (13) is compressed and flows into the expansion cylinder (2) via the communication pipe (4) (ideally, isothermal compression). In the process of FIG. 5, this gas passes through the cold storage material (14) in the displacer (6) and exchanges heat with the cold storage material (14) to lower the temperature (constant volume cooling). The gas that has passed through the cold storage material (14) flows into the expansion space (11) of the expansion cylinder (2) in the process of FIG. 5, and then expands as the displacer (6) descends (ideally, Isothermal expansion). Next, in the process of FIG. 5, as the displacer (6) rises, the gas in the expansion space (11) passes through the cold storage material (14) and exchanges heat with the cold storage material (14). After the temperature rises, it flows into the compression space (13) again via the communication pipe (4) (fixed volume heating).

As a result, the cold head (15) provided at the head of the expansion cylinder (2) is cooled. The displacer (6) is a cylinder (17) filled with a cold storage material (14) as shown in FIG. 4, and the cold storage material (14) made of sintered metal is used as described above. Heat exchange is performed with the working gas G, and thermal deformation occurs due to a temperature difference (for example, about 200 ° C.) generated at that time.

Therefore, a certain gap (for example, about 0.5 mm) is provided between the cold storage material (14) and the cylindrical body (17) as shown in the figure for free thermal deformation of the cold storage material (14). Things are going on.

Further, there is a limit to the processing accuracy when the cold storage material (14) is formed from a sintered metal, and the cold storage material (1) is required for assembly.
In order to load 4) into the inside of the cylindrical body (17), the fitting of both must be a clearance fitting.

[0013]

However, if there is a gap between the cold storage material (14) and the cylindrical body (17), it flows from the opening (18) of the cylindrical body (17) into the cold storage material (14). The working gas leaks from the outer peripheral surface of the cold storage material (14) to the gap space as shown by the arrow, goes straight through the gap space having a small flow resistance, and performs almost no heat exchange with the cold storage material (14). It will flow out of the opening (19) of (17). As a result, there is a problem that the heat exchange performance of the reheat exchanger constituted by the displacer (6) is reduced, and thereby the coefficient of performance of the Stirling refrigerator is significantly reduced. This problem is caused by stacking several hundreds or more metal meshes in which metal wires are woven, and forming a cold storage material (1) inside the cylindrical body (17).
The same applies to the case of filling as 4). The same applies to not only the Stirling refrigerator but also other gas compression / expansion machines equipped with a regenerative heat exchanger.

An object of the present invention is to improve the heat exchange performance of a regenerative heat exchanger, thereby increasing the thermal efficiency of a gas compression and expansion machine.

[0015]

SUMMARY OF THE INVENTION The present invention provides a regenerative heat exchanger for a gas compression / expansion machine in which a heat exchange filler through which a working gas can pass is disposed inside a tubular body having both ends opened. Wherein a gap between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the filler is filled with a granular member.

By using this configuration, even if the working gas that has flowed into the filler leaks into the gap space between the cylinder and the cylinder, the gap space is filled with the granular member and is filled in the axial direction of the cylinder. The working gas in the clearance space becomes turbulent and collides with the surface of the filler because of the flow path having a large flow resistance bent along. Further, as the flow resistance increases, the flow rate of the working gas leaking from the filler decreases.

As a result, most of the working gas that has flowed into the filler from the opening of the cylindrical body passes through the inside of the filler without leaking, and sufficiently exchanges heat with the filler.
Further, the thermal deformation of the filler is absorbed by the movement of the granular member in the space between the inner peripheral surface of the cylindrical body and the outer peripheral surface of the filler.
Therefore, there is no fear that the cylindrical body is deformed.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where the present invention is applied to a displacer of a Stirling refrigerator shown in FIG. 3 will be described in detail with reference to the drawings. Since the operation of the Stirling refrigerator is the same as that of the conventional one, the description is omitted.

The displacer (21) shown in FIG. 1 is filled with several hundreds or more metal meshes (23) in which metal wires made of stainless steel or copper are braided inside a resin cylinder (22). At the same time, a gap between the inner peripheral surface of the cylindrical body (22) and the outer peripheral surface of the laminated metal mesh (23) is filled with a granular member (24) formed of a copper alloy material having a particle size of 150 to 200 μm. .

On the other hand, the working gas such as helium sent from the compression space of the compression cylinder (3) to the expansion cylinder (2) flows from one opening of the cylindrical body (22) to the laminated metal mesh (23) as a cold storage material. Most of the cold storage material (23) passes through the inside of the cold storage material (23).
After sufficient heat exchange, the gas flows out of the other opening of the cylindrical body (22) into the expansion space of the expansion cylinder.

Here, a very small part of the working gas is supplied to the cylinder (2).
It leaks into the gap space between the inner peripheral surface of 2) and the outer peripheral surface of the cold storage material (23). However, as shown in FIG. 2, a granular member (24) formed of a copper alloy material having a particle size of 150 to 200 μm is provided in a gap between the inner peripheral surface of the cylindrical body (22) and the outer peripheral surface of the laminated metal mesh (23). Is filled at a filling rate of about 60%, so that the inner peripheral surface of the cylindrical body (22) and the cold storage material (2) are filled.
The working gas leaked into the gap space between the outer peripheral surfaces in 3) cannot travel straight in the cylinder axis direction as in the conventional case, and the flow path is disturbed and becomes longer, and the flow resistance increases accordingly.

As a result, the flow rate of the gas leaking from the inside of the cold storage material (23) to the gap space becomes extremely small, and most of the working gas flowing into the cold storage material (23) flows through the cold storage material (23). And sufficient heat exchange with the cold storage material (23). Further, since the granular member (24) is filled in the gap between the inner peripheral surface of the cylindrical body (22) and the outer peripheral surface of the cold storage material (23), the cold storage material (23) expands or contracts due to a temperature change. Also in this case, the granular member (24) moves in the gap to disperse the stress due to thermal deformation of the cold storage material (23) due to expansion or contraction, and the tubular body (22) may be damaged by the stress due to the thermal deformation. Absent.

The description of the above embodiments is for the purpose of describing the present invention, and should not be construed as limiting the invention described in the claims or reducing the scope thereof.
Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

For example, the cold storage material (23) is made of stainless steel,
It may be formed from a sintered metal such as copper or lead. Further, stainless steel or lead may be used as the granular member (24) in addition to the copper alloy.

Further, the present invention is not limited to a Stirling refrigerator having a regenerative material incorporated in a displacer as shown in FIG. 3, but may be any type of gas compression / expansion machine such as a regenerative heat exchanger which is arranged separately from the displacer. Needless to say, it can be implemented.

[0026]

As described above, according to the present invention, since the working gas and the filler are sufficiently in contact with each other to perform heat exchange, good heat exchange performance is achieved. As a result, the thermal efficiency of the gas compression and expansion machine is reduced. It will be expensive.

[Brief description of the drawings]

FIG. 1 is a partially broken perspective view of a displacer according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the displacer of FIG. 1;

FIG. 3 is a sectional view of a Stirling refrigerator in which the present invention is to be implemented.

FIG. 4 is a sectional view of a conventional displacer.

FIG. 5 is a diagram illustrating a process of a Stirling refrigeration cycle.

[Explanation of symbols]

 (21) Displacer (22) Cylindrical body (23) Metal mesh (cool storage material) (24) Granular member

Continuation of front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F25B 9/00

Claims (2)

(57) [Claims] In a regenerative heat exchanger of a gas compression / expansion machine, a heat exchange filler through which a working gas can pass is disposed inside a cylindrical body having both ends opened. A regenerative heat exchanger for a gas compression / expansion machine, wherein a plurality of granular members are filled in a gap between a peripheral surface and an outer peripheral surface of a filler. 2. The method according to claim 1, wherein the granular member has a particle size of 150 to 20.
2. The regenerative heat exchanger for a gas compression / expansion machine according to claim 1, wherein the regenerative heat exchanger is made of a copper alloy having a thickness of 0 [mu] m.