JP2020026788A - Two-phase flow turbine and refrigerating machine including the same - Google Patents

Abstract

To provide a two-phase flow turbine capable of using rotation of an expansion turbine for power recovery and gas-liquid separation of gas-liquid two-phase refrigerant, and a refrigerating machine including the same.SOLUTION: A two-phase flow turbine 30 comprises: an expansion turbine 32 that rotates by expanding refrigerant between a plurality of blades 33b; a power recovery device 60 that is driven by the rotation of the expansion turbine 32; and a separation container 40 that forms a space surrounding the downstream side of the refrigerant flow of the expansion turbine 32, wherein with the rotation of the expansion turbine 32, the refrigerant guided to the expansion turbine 32 is centrifuged into liquid refrigerant and gas refrigerant and then discharged.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a two-phase flow turbine and a refrigerator including the same.

  In a refrigerant circuit including a compressor, a condenser, an expansion valve, and an evaporator, the refrigerant expanded by the expansion valve becomes a gas-liquid two-phase refrigerant. In order to increase the cycle efficiency, it is known that this gas-liquid two-phase refrigerant is separated into a liquid refrigerant and a gas refrigerant by a gas-liquid separator, the liquid refrigerant is guided to an evaporator, and the gas refrigerant is recirculated to a compressor. Have been. However, the problem is that the cost of installing the gas-liquid separator increases.

  Patent Literature 1 discloses an invention that achieves high cycle efficiency by recovering power from rotational energy by using an expander instead of an expansion valve.

U.S. Pat. No. 5,467,613

  However, in the invention disclosed in Patent Document 1, although the power is recovered from the rotational energy to achieve high cycle efficiency, the working fluid (refrigerant), which has been reduced in pressure by the expander, is directly discharged together with the gas phase component. Guided to the evaporator. However, if the working fluid led to the evaporator contains a gas phase, the heat exchange efficiency in the evaporator may be reduced. On the other hand, it is conceivable to install a gas-liquid separator between the expander and the evaporator in order to remove the gas phase from the working fluid. However, when the gas-liquid separator is installed, there is a concern that it may hinder space saving and increase costs.

  The present invention has been made in view of such circumstances, and a two-phase flow turbine capable of utilizing the rotation of an expansion turbine for power recovery and gas-liquid separation of a gas-liquid two-phase refrigerant, and a refrigerator including the same. The purpose is to provide.

In order to solve the above problems, a two-phase flow turbine of the present invention and a refrigerator including the same employ the following means.
That is, the two-phase flow turbine according to one aspect of the present invention includes an expansion turbine that rotates by expanding a refrigerant between a plurality of blades, a power recovery device driven by rotation of the expansion turbine, A separation vessel forming a space surrounding the downstream side of the refrigerant flow, wherein the refrigerant guided to the expansion turbine is centrifuged into a liquid refrigerant and a gas refrigerant and discharged by rotation of the expansion turbine.

  The two-phase flow turbine according to this aspect includes an expansion turbine that rotates by expanding the refrigerant, a power recovery device that is rotated by the expansion turbine, and a separation container that forms a space surrounding the refrigerant flow downstream of the expansion turbine. And a gas-liquid two-phase refrigerant guided to the expansion turbine by centrifugation into a liquid refrigerant and a gas refrigerant by the rotation of the expansion turbine, and discharged. Thus, power can be recovered from the rotation of the expansion turbine by the power unit, and the rotation can be used for centrifugation of the gas-liquid two-phase refrigerant. In other words, the rotation of the expansion turbine can be used for power recovery and centrifugal separation of the gas-liquid two-phase refrigerant, thereby realizing a high-performance two-phase flow turbine. Since the liquid refrigerant and the gas refrigerant separated by centrifugation are separately stored in the space inside the separation container, the two-phase flow turbine also has a function as a gas-liquid separator. For example, when this two-phase flow turbine is used as an expansion mechanism of a refrigerant circuit, it is not necessary to separately provide a gas-liquid separator, and the cost of the refrigerator can be reduced. The power recovery device is, for example, an electric motor that drives a generator or a compressor.

  Further, in the two-phase flow turbine according to one aspect of the present invention, the separation vessel has a portion in which a gap between the downstream end of the refrigerant flow of the blade and the separation vessel opposed thereto is longer than the blade length of the blade. It is a container.

  In the two-phase flow turbine according to this aspect, the separation vessel is a vessel having a portion in which the gap between the downstream end (blade tip) of the refrigerant flow of the blades of the expansion turbine and the separation vessel facing the same is longer than the blade length. . As a result, the flow velocity of the gas refrigerant from the blade tip toward the portion where the gap is longer than the blade length is easily reduced. When the gas refrigerant is decelerated and the flow velocity is reduced, the droplets of the liquid refrigerant present near the gas refrigerant hardly accompany the gas refrigerant, so that the droplets of the liquid refrigerant in the flow field flow into the gas refrigerant. Entanglement can be suppressed. If the gas refrigerant is not sufficiently decelerated and has a high flow velocity, the droplets may accompany the flow of the gas refrigerant. Then, the liquid refrigerant flows into the downstream side to which only the gas refrigerant should go. As a method of ensuring a large gap, for example, there is an enlargement of a separation vessel that forms a space surrounding the downstream side of the refrigerant flow of the expansion turbine.

  Further, the two-phase flow turbine according to one aspect of the present invention has a tubular airflow pipe having an opening in the space, and guiding the gas refrigerant stored in the space to the outside of the space through the opening. And the opening is located outside a region where the liquid refrigerant discharged from the blades by the rotation of the expansion turbine is scattered.

  The two-phase flow turbine according to the present aspect includes a tubular airflow tube having an opening in the space and guiding the gas refrigerant stored in the space to the outside of the space through the opening, and the opening is a rotation of the expansion turbine. Is located outside the region where the liquid refrigerant discharged from the wings scatters. Thus, the scattered liquid refrigerant does not directly touch the opening, so that the phenomenon that the scattered liquid refrigerant is caught in the airflow tube can be suppressed.

  Further, in the two-phase flow turbine according to one aspect of the present invention, the opening is an opening facing a flow direction of the gas refrigerant discharged from the blade, and the airflow tube has a curved portion immediately after the opening. are doing.

  In the two-phase flow turbine according to this aspect, the opening is an opening directed in the flow direction of the gas refrigerant discharged from the blade. Thus, the gas refrigerant can be smoothly guided to the opening (airflow pipe). The airflow tube has a curved portion. Thereby, the droplet (liquid refrigerant) in the gas stream slightly existing in the gas refrigerant can be attached to the curved portion by its inertia force. By collecting the attached liquid droplets, the liquid droplets can be returned into the separation container (liquid side) as drain. Further, since the airflow tube has a curved portion immediately after the opening, it is not necessary to extend the airflow tube in the flow direction of the gas refrigerant discharged from the blades, so that the space can be reduced.

  The two-phase turbine according to one aspect of the present invention includes a filter that covers the opening.

  The two-phase flow turbine according to this aspect includes a filter that covers the opening. As a result, droplets (liquid refrigerant) in the gas stream slightly present in the gas refrigerant can be collected by the filter. The collected droplets can be returned into the separation vessel (liquid phase side) as drain. As the filter, for example, a metal filter such as a wire net is used.

  In the two-phase flow turbine according to one aspect of the present invention, the power recovery device is a generator.

  In the two-phase flow turbine according to this aspect, the power recovery device is a generator. Thereby, the rotation of the expansion turbine can be used for power generation.

  In the two-phase flow turbine according to one aspect of the present invention, the power recovery device is an electric motor that drives a compressor.

  In the two-phase flow turbine according to this aspect, the power recovery device is an electric motor that drives the compressor. Thus, the rotation of the expansion turbine can be used for assisting the driving of the compressor.

  Further, in the two-phase flow turbine according to one aspect of the present invention, a direction of a rotation axis of the expansion turbine is a vertical direction or a horizontal direction.

  In the two-phase flow turbine according to this aspect, the direction of the rotation axis of the expansion turbine is a vertical direction or a horizontal direction. When the direction of the rotation axis is the vertical direction, a structure can be realized in which the liquid refrigerant discharged from the expansion turbine easily falls by gravity, and the liquid refrigerant can be easily stored vertically below the separation container. On the other hand, when the direction of the rotation axis is the horizontal direction, the liquid refrigerant discharged from the blade tip (the downstream end of the refrigerant flow) of the expansion turbine scatters in a substantially vertical direction, so that the scatter range in the horizontal direction can be reduced. Accordingly, it is not necessary to protrude the air flow tube extremely into the separation container in order to locate the opening of the air flow tube outside the region where the liquid refrigerant discharged from the wings scatters, and the separation container can be made compact. .

  Further, a refrigerator according to one embodiment of the present invention is a compressor that compresses a refrigerant, a condenser that condenses the refrigerant compressed by the compressor, and an expansion mechanism that expands the refrigerant condensed by the condenser. And a evaporator for evaporating the refrigerant expanded by the expansion mechanism, wherein the expansion mechanism is the above-described two-phase flow turbine.

  According to the refrigerator of this aspect, the two-phase turbine described above is used as an expansion mechanism of the refrigerant circuit. As a result, since gas-liquid separation is performed by the two-phase flow turbine, it is not necessary to separately provide a gas-liquid separator if only the centrifugally separated liquid refrigerant is guided to the evaporator, and cost reduction as a refrigerator is realized. . Further, the efficiency of the cycle is improved by guiding the centrifugally separated gas refrigerant to, for example, the middle stage of the multi-stage compressor. Furthermore, since the power is recovered by the two-phase flow turbine, the efficiency of the cycle is further improved.

  According to the two-phase flow turbine of the present invention, the rotation of the expansion turbine can be used for power recovery and gas-liquid separation of the gas-liquid two-phase refrigerant. Further, a refrigerator having the expansion turbine can be provided.

It is a figure showing a refrigerant cycle provided with a two-phase flow turbine concerning one embodiment of the present invention. FIG. 1 is a diagram illustrating a two-phase flow turbine according to a first embodiment of the present invention. It is a figure showing a two-phase flow turbine concerning a 2nd embodiment of the present invention. It is a figure showing a two-phase flow turbine concerning a 3rd embodiment of the present invention. FIG. 9 is a diagram showing a modification of the two-phase flow turbine according to one embodiment of the present invention.

  Hereinafter, a two-phase flow turbine according to an embodiment of the present invention and a refrigerator including the same will be described with reference to the drawings.

[First Embodiment]
First, a two-phase flow turbine according to a first embodiment of the present invention and a refrigerator including the same will be described.

  FIG. 1 shows a refrigerant circuit 1 in which a two-phase flow turbine 30A according to the present embodiment is provided as an expansion mechanism.

  The refrigerant circuit 1 is, for example, a refrigerant circuit provided in a turbo refrigerator, and is compressed by the turbo compressor 10 (hereinafter, referred to as “compressor 10”) that compresses the refrigerant charged in the refrigerant circuit 1, and is compressed by the compressor 10. , A two-phase flow turbine 30A as an expansion mechanism for expanding the refrigerant condensed in the condenser 12, and a part (liquid refrigerant) of the refrigerant expanded in the two-phase flow turbine 30A. And an evaporator 14 for evaporating.

  The refrigerant circuit 1 is configured by connecting these devices by piping. Specifically, a refrigerant outlet (discharge port) of the compressor 10 and a refrigerant inlet of the condenser 12 are connected by a refrigerant pipe P1. A refrigerant outlet of the condenser 12 and a liquid refrigerant supply pipe 38 (described later) of the two-phase flow turbine 30A are connected by a refrigerant pipe P2. A liquid phase portion (described later) of the separation vessel 40 of the two-phase flow turbine 30A and a refrigerant inlet of the evaporator 14 are connected by a liquid refrigerant pipe P3A (described later). The refrigerant outlet of the evaporator 14 and the refrigerant inlet (suction port) of the compressor 10 are connected by a refrigerant pipe P4. The compressor 10 is a multi-stage (for example, two-stage) compressor, and the low-pressure stage and the high-pressure stage are connected by a refrigerant pipe P5. Further, a gas phase portion (described later) of the separation vessel 40 of the two-phase flow turbine 30A and the refrigerant pipe P5 are connected by an airflow tube P3B (described later).

  The high-temperature and high-pressure gas refrigerant discharged from the compressor 10 that compresses the refrigerant by an impeller or the like driven by an electric motor flows through the refrigerant pipe P1 and is guided to the condenser 12.

  The high-temperature and high-pressure gas refrigerant guided to the condenser 12 undergoes heat exchange by a heat transfer tube provided in the container of the condenser 12 to become a high-pressure liquid refrigerant. This high-pressure liquid refrigerant flows through the refrigerant pipe P2 and is guided to the two-phase flow turbine 30A.

  The high-pressure liquid refrigerant guided to the two-phase flow turbine 30A is expanded by the two-phase flow turbine 30A to become a low-temperature low-pressure gas-liquid two-phase refrigerant. Further, the low-temperature and low-pressure gas-liquid two-phase refrigerant is separated into a liquid refrigerant and a gas refrigerant by gas-liquid separation by the two-phase turbine 30A. Details of the two-phase flow turbine 30A will be described later.

  The low-temperature and low-pressure liquid refrigerant gas-liquid separated by the two-phase flow turbine 30A flows through the liquid refrigerant pipe P3A and is guided to the evaporator 14.

  The low-temperature and low-pressure liquid refrigerant guided to the evaporator 14 undergoes heat exchange by a heat transfer tube provided in the container of the evaporator 14 to become a low-pressure gas refrigerant. This low-pressure gas refrigerant flows through the refrigerant pipe P4 and is again guided to the compressor 10.

  On the other hand, the gas refrigerant gas-liquid separated by the two-phase flow turbine 30A flows through the airflow pipe P3B, is guided to the refrigerant pipe P5 connecting the low pressure stage and the high pressure stage of the compressor 10, and is moved to the high pressure stage of the compressor 10. Supplied.

Next, the structure of the two-phase flow turbine 30A will be described in detail.
As shown in FIG. 2, the two-phase flow turbine 30A includes an expansion turbine 32, a generator 60 as a power recovery device, and a separation vessel 40.

  The expansion turbine 32 includes a shaft 34 extending along the rotation axis X, and an impeller 33 connected to one end of the shaft 34. In the case of FIG. 2, the rotation axis X coincides with the vertical direction.

  The impeller 33 has a hub 33a and a plurality of blades 33b connected in a circumferential direction of the hub 33a. A liquid refrigerant supply pipe 38 connected to the refrigerant pipe P2 is provided upstream of the impeller 33. Further, a nozzle 38a is connected to the liquid refrigerant supply pipe 38, and the tip of the nozzle 38a is configured to face a blade 33b of the impeller 33.

  The shaft 34 is rotatably supported by a bearing 36 and can rotate around a rotation axis X. Although one bearing 36 is shown in FIG. 2, the shaft 34 may be rotatably supported by two or more bearings 36.

  The drive shaft of the generator 60 is connected to the other end of the shaft 34 and is driven by the rotation of the shaft 34. That is, the rotation of the shaft 34 rotates the drive shaft of the generator 60 to generate electric power.

  The separation container 40 is a metal container that surrounds the impeller 33 of the expansion turbine 32 and that forms a space extending in the rotation axis X direction. A liquid refrigerant pipe P3A is connected vertically below the separation container 40. An air flow pipe P3B is provided on the side surface of the separation container 40 so as to penetrate therethrough, and an opening 42 at one end of the air flow pipe P3B is located in a space formed by the separation container 40.

Next, the operation of the two-phase flow turbine 30A will be described in detail.
The high-pressure liquid refrigerant supplied from the refrigerant pipe P2 to the liquid refrigerant supply pipe 38 is injected toward the plurality of blades 33b via the nozzle 38a.

  The high-pressure liquid refrigerant injected into the plurality of blades 33b expands while passing between the blades 33b, thereby becoming a low-temperature and low-pressure gas-liquid two-phase refrigerant. In addition, the impeller 33 rotates around the rotation axis X when the blade 33b receives the force generated by the expansion. The shaft 34 rotates around the rotation axis X with the rotation of the impeller 33. That is, the expansion turbine 32 rotates around the rotation axis X.

  With the rotation of the expansion turbine 32, the drive shaft of the generator 60 connected to the other end of the shaft 34 is rotated.

  The refrigerant expanded into the low-temperature and low-pressure gas-liquid two-phase refrigerant by the expansion turbine 32 is centrifuged by the rotation of the impeller 33 and is separated into a liquid refrigerant and a gas refrigerant. At this time, the liquid refrigerant having a large specific gravity is mainly discharged from the end (wing tip) of the blade 33b. On the other hand, the gas refrigerant having a small specific gravity is mainly discharged from an intermediate portion of the blade 33b.

  The liquid refrigerant discharged from the wing tip of the wing 33b and turned into a droplet scatters toward the surrounding separation container 40 by the action of centrifugal force. The scattered liquid refrigerant travels along the inner wall of the separation container 40 and is collected and stored in the liquid phase portion on the vertically lower side of the separation container 40. The collected and stored liquid refrigerant flows into a liquid refrigerant pipe P3A connected to the separation container 40.

  On the other hand, the gas refrigerant discharged from the intermediate portion of the blade 33b is stored in the space of the separation container 40 in the gas phase portion vertically above the liquid phase portion in which the liquid refrigerant is stored. Since the airflow pipe P3B is installed so that the opening 42 is located in the gas phase portion where the gas refrigerant is stored, the stored gas refrigerant flows through the airflow pipe P3B.

  At this time, it is desirable that the opening 42 of the airflow pipe P3B is located outside the region where the liquid refrigerant discharged from the blade 33b scatters. That is, it is desirable that the opening 42 is arranged at a position where it does not directly touch the scattered liquid refrigerant. Here, the expression “the refrigerant does not directly touch” means that, for example, when the scattered liquid refrigerant flies according to the inertial force, the refrigerant directly contacts the obstacle without colliding with another obstacle.

According to the present embodiment, the following effects can be obtained.
Power is recovered by the generator 60 from the rotation of the expansion turbine 32, and the rotation of the expansion turbine 32 can be used for centrifugation of the gas-liquid two-phase refrigerant. That is, the rotation of the expansion turbine 32 can be used for power recovery and centrifugal separation of the gas-liquid two-phase refrigerant, and the high-performance two-phase flow turbine 30A is realized.
Since the liquid refrigerant and the gas refrigerant separated by centrifugation are separately stored in the space inside the separation container 40, the two-phase flow turbine 30A also has a function as a gas-liquid separator. For example, when the two-phase flow turbine 30A is used as an expansion mechanism of the refrigerant circuit 1, it is not necessary to separately provide a gas-liquid separator, and the cost of the refrigerator is reduced.

  Further, since the scattered liquid refrigerant does not directly touch the opening 42, the phenomenon in which the scattered liquid refrigerant is caught in the airflow pipe P3B can be suppressed.

  When the rotation axis X coincides with the vertical direction, the liquid refrigerant discharged from the expansion turbine 32 easily falls by gravity, and the liquid refrigerant is easily stored vertically below the separation container 40.

[Second embodiment]
Next, a two-phase flow turbine according to a second embodiment of the present invention will be described.
The two-phase flow turbine 30B of the present embodiment differs from the first embodiment in the form of the separation vessel 40 and the arrangement of the expansion turbine 32, and is otherwise the same. Therefore, only the points different from the first embodiment will be described, and the description of the other parts will be omitted using the same reference numerals.

  As shown in FIG. 3, in the direction in which the liquid refrigerant scatters, the separation container 40 forms a space having an inner diameter sufficiently larger than the diameter of the impeller 33. In the horizontal direction, the rotation axis X of the expansion turbine 32 is asymmetrically arranged with respect to the separation container 40. That is, the rotation axis X is offset with respect to the center line X2 in the width direction (the left-right direction in FIG. 3) of the separation container 40. In the case of the figure, the rotation axis X is shifted to the left with respect to the center line X2 of the separation container 40.

  With the configuration as shown in FIG. 3, a portion (a portion on the right side from the center line X2 in FIG. 3) in which a gap between the blade tip of the blade 33b and the inner wall of the separation container 40 facing the blade 33b is sufficiently secured is formed. it can. This gap may be, for example, at least as long as the blade length of the blade 33b.

  The configuration for securing the gap is not limited to the configuration shown in FIG. 3, but may be a configuration in which the gap between the blade tip of the blade 33 b and the inner wall of the separation vessel 40 facing the blade is longer than the blade length. I just want it.

  Further, as in the first embodiment, it is desirable that the opening 42 of the airflow pipe P3B is located outside the region where the liquid refrigerant discharged from the blades 33b scatters. That is, it is desirable that the opening 42 is arranged at a position where it does not directly touch the scattered liquid refrigerant.

According to the present embodiment, the following effects can be obtained.
The gap having a length equal to or longer than the blade length facilitates a reduction in the flow velocity of the gas refrigerant from the blade tip of the blade 33b toward the inner wall of the separation vessel 40. When the gas refrigerant is decelerated and the flow velocity is reduced, the droplets of the liquid refrigerant present near the gas refrigerant hardly accompany the gas refrigerant. Entanglement can be suppressed.
If the gas refrigerant is not sufficiently decelerated and has a high flow velocity, the droplets may accompany the flow of the gas refrigerant. Then, the liquid refrigerant flows into the airflow pipe P3B to which only the gas refrigerant should go.

  In addition, by ensuring a sufficient gap between the wing tip of the wing 33b and the inner wall of the separation vessel 40 facing the wing tip, it becomes easy to install the airflow pipe P3B in an empty space.

[Third embodiment]
Next, a two-phase flow turbine according to a third embodiment of the present invention will be described.
The two-phase flow turbine 30C of the present embodiment is different from the first and second embodiments in the form of the separation vessel 40 and the arrangement of the expansion turbine 32, and is otherwise the same. Therefore, only the differences from the first and second embodiments will be described, and the description of the other components will be omitted by using the same reference numerals.

  As shown in FIG. 4, the expansion turbine 32 is arranged so that the rotation axis X coincides with the horizontal direction. Also, the liquid refrigerant centrifuged by the impeller 33 of the expansion turbine 32 is collected and stored vertically below the separation container 40 by its own weight, so that the liquid refrigerant pipe P3A is connected vertically below the separation container 40. ing.

  The inner wall on the upper side in the vertical direction of the separation container 40 is inclined downward so that the scattered and adhered liquid refrigerant does not drop and travels to the liquid phase portion.

  Note that, similarly to the above-described embodiments, the opening 42 of the airflow pipe P3B is desirably located outside the region where the liquid refrigerant discharged from the blades 33b scatters. That is, it is desirable that the opening 42 is arranged at a position where it does not directly touch the scattered liquid refrigerant.

According to the present embodiment, the following effects can be obtained.
Since the rotation axis X coincides with the horizontal direction, the liquid refrigerant discharged from the blade tip of the blade 33b scatters in a substantially vertical direction. Since the direction of gravity acting on the liquid refrigerant coincides with the direction in which the refrigerant scatters, the scattering range of the liquid refrigerant in the direction of the rotation axis X can be reduced. This eliminates the need to protrude the airflow pipe P3B extremely into the separation vessel 40 in order to locate the opening 42 of the airflow pipe P3B outside the area where the liquid refrigerant discharged from the blades 33b scatters. Compactness can be realized.
If the rotation axis X is aligned with the vertical direction, the liquid refrigerant discharged from the blade tip of the blade 33b scatters in a substantially horizontal direction. Since the direction of gravity acting on the liquid refrigerant does not coincide with the direction in which the refrigerant scatters, the scatter range of the liquid refrigerant in the direction of the rotation axis X increases. Then, in order to locate the opening 42 of the airflow pipe P3B outside the area where the liquid refrigerant discharged from the blades 33b scatters, the airflow pipe P3B must protrude extremely into the separation container 40.

  In the first to third embodiments, as shown in FIG. 5, instead of the generator 60, a power recovery device may be an electric motor 62 used for driving the compressor 10. In this case, the rotation of the expansion turbine 32 can be used to assist in driving the compressor 10.

  In addition, as shown in FIG. 5, it is preferable that the opening 42 be arranged so as to face the flow direction of the gas refrigerant discharged from the blade 33b. Thus, the gas refrigerant can be smoothly guided to the opening 42 (the airflow pipe P3B). Further, a curved portion 43 for deflecting the traveling direction of the introduced gas refrigerant may be provided in the airflow pipe P3B immediately after the opening 42. Thereby, the droplet (liquid refrigerant) in the gas stream slightly existing in the gas refrigerant can be attached to the curved portion 43 by its inertia force. By collecting the attached droplets, the liquid droplets can be returned to the liquid phase portion of the separation container 40 as drain. Further, the curved portion 43 eliminates the need to extend the airflow pipe P3B in the flow direction of the gas refrigerant discharged from the blades 33b, so that the space can be reduced.

  Further, as shown in FIG. 4, a filter 44 covering the opening 42 may be attached. As the filter 44, a metal filter such as a wire net is used, for example. This allows the filter 44 to collect droplets (liquid refrigerant) in the gas stream slightly present in the gas refrigerant. The collected droplets can be returned to the liquid phase portion of the separation container 40 as drain. The filter 44 is, for example, a mesh having one side of about 10 to 100 μm.

DESCRIPTION OF SYMBOLS 1 Refrigerant circuit 10 Compressor 12 Condenser 14 Evaporator 30 (30A, 30B, 30C) Two-phase flow turbine (expansion mechanism)
32 Expansion Turbine 33 Impeller 33a Hub 33b Blade 34 Shaft 36 Bearing 38 Liquid Refrigerant Supply Pipe 38a Nozzle 40 Separation Vessel 42 Opening 43 Curved Portion 44 Filter 60 Generator (Power Recovery Device)
62 electric motor (power recovery device)
P1, P2, P4, P5 Refrigerant pipe P3A Liquid refrigerant pipe P3B Air flow pipe X Rotation axis

Claims (9)

An expansion turbine that rotates by expanding a refrigerant between a plurality of blades,
A power recovery device driven by rotation of the expansion turbine,
A separation vessel forming a space surrounding the downstream side of the refrigerant flow of the expansion turbine,
With
A two-phase flow turbine that centrifugally separates a refrigerant guided to the expansion turbine into a liquid refrigerant and a gas refrigerant by rotation of the expansion turbine and discharges the refrigerant.   2. The two-phase flow turbine according to claim 1, wherein the separation vessel is a vessel having a portion in which a gap between a downstream end of the refrigerant flow of the blade and the separation container facing the separation blade is longer than a blade length of the blade. . An opening is provided inside the space, and a gaseous refrigerant stored in the space is provided with a tubular airflow pipe that guides the gas refrigerant out of the space through the opening.
3. The two-phase flow turbine according to claim 1, wherein the opening is located outside a region where the liquid refrigerant discharged from the blade by the rotation of the expansion turbine is scattered. 4. The opening is an opening facing the flow direction of the gas refrigerant discharged from the wing,
The two-phase flow turbine according to claim 3, wherein the airflow tube has a curved portion immediately after the opening.   The two-phase flow turbine according to claim 3, further comprising a filter covering the opening.   The two-phase flow turbine according to any one of claims 1 to 5, wherein the power recovery device is a generator.   The two-phase flow turbine according to any one of claims 1 to 5, wherein the power recovery device is an electric motor that drives a compressor.   The two-phase flow turbine according to any one of claims 1 to 7, wherein a direction of a rotation axis of the expansion turbine is a vertical direction or a horizontal direction. A compressor for compressing the refrigerant,
A condenser for condensing the refrigerant compressed by the compressor,
An expansion mechanism for expanding the refrigerant condensed in the condenser,
An evaporator for evaporating the refrigerant expanded by the expansion mechanism,
A refrigerator comprising:
The refrigerator, wherein the expansion mechanism is the two-phase flow turbine according to any one of claims 1 to 8.

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