WO2013031618A1 - Closed- and gas circulation-type freezing apparatus and operation method thereof - Google Patents

Abstract

A closed- and gas circulation-type freezing apparatus (10A) of the present invention first cools a high-temperature and high-pressure refrigerant air compressed by a compressor (22) with a water-cooled heat exchanger (16) and a heat recovery heat exchanger (18), and then expands the air at an expander (26) to turn the air into a low-pressure refrigerant air having an extremely low temperature. The low-temperature and low-pressure refrigerant air is supplied to a brine cooler (20). A closed system refrigerant air supply and discharge device (50) is installed, which comprises an expansion tank (51), a compressor inlet side connection (52), and a compressor outlet side connection (54). A pressure sensor (62) is used to detect a pressure of the refrigerant air of a compressor inlet side refrigerant air passage (12a). The refrigerant air is supplied and discharged between the expansion tank (51) and the compressor inlet side refrigerant air passage (12a) or a compressor outlet side refrigerant air passage (12b) so that the pressure of the refrigerant air remain in a predetermined range.

Description

Closed gas circulation refrigeration system and operation method thereof

The present invention relates to a refrigeration apparatus such as an air refrigerant type refrigeration apparatus that cools by sensible heat of a gas circulating in a gas phase, and more specifically, the refrigerant gas pressure in a compressor suction side refrigerant gas path can be adjusted. The present invention relates to a closed-type gas circulation refrigeration apparatus.

Air is used as the refrigerant, high-pressure high-temperature air is used in the compressor, and this is cooled by a cooler using cooling water or a cold-heat recovery heat exchanger, and then low-pressure by an expander driven by the same drive shaft as the compressor. There is known an air refrigerant refrigeration apparatus that uses low-temperature air and performs cooling with sensible heat of the low-temperature and low-pressure air. Since the air refrigerant refrigeration apparatus does not use refrigerants such as Freon and ammonia, there is an advantage that the environment is not harmed.

In such an air refrigerant refrigeration apparatus, an open-type air refrigerant refrigeration apparatus (hereinafter referred to as an open-type apparatus) in which a part of the refrigerant air circulation system is provided with an atmosphere open end and the refrigerant air circulation system are connected to the atmosphere. There is a closed type air refrigerant refrigeration apparatus (hereinafter referred to as a closed type apparatus) that is closed. The open type device, for example, discharges low-temperature air at the outlet side of the expander in the freezer, cools the object to be cooled with this low-temperature air, and supplies the air after cooling to the compressor suction connected to the compressor suction port It is returned to the side refrigerant air path. Therefore, the refrigerant air pressure in the compressor suction side refrigerant air passage is always maintained at atmospheric pressure. On the other hand, since the refrigerant air circulation system is closed to the atmosphere, the closed-type air refrigerant refrigeration system exchanges heat between the low-temperature air on the outlet side of the expander and the brine, and cools the object to be cooled with the cooled brine. It has a heat exchange configuration with a brine to be cooled. For this reason, the compressor suction side refrigerant air pressure varies depending on the operating state and is not constant.

When the closed-type air refrigerant refrigeration system starts operating at atmospheric pressure, the refrigerant air in the refrigerant air circulation system gradually cools, and the air pressure in the refrigerant air circulation system gradually decreases as the volume decreases. In the compressor suction side, negative pressure is applied. For this reason, the compression function of the compressor and the cooling function of the expander are abruptly reduced or cause a failure. Therefore, the open-type device and the closed-type device cannot be used with the same design specifications (such as pressure), and devices with different design specifications are required, resulting in high costs.

If the compressor suction side refrigerant air pressure of the closed type device can be adjusted, the pressure on the compressor suction side can be adjusted to atmospheric pressure, the deterioration of the cooling function can be eliminated, and the pressure resistance of the closed type device can be reduced with one model. In addition to being able to be used as an open type device, when used as a closed type device, the deterioration of the cooling function can be eliminated.

For example, Patent Document 1 is disclosed as a technique that makes it possible to adjust the compressor suction side refrigerant air pressure.
The device of Patent Document 1 is an open-type device, but when the compressor suction pressure is abnormally reduced, when dry air is supplied to the refrigerant flow path and the compressor suction pressure becomes equal to or higher than atmospheric pressure, a part of the refrigerant air Is provided with a flow path blockage prevention and pressure adjusting means for releasing the air to the outside.
The device disclosed in Patent Document 1 is an open-type device that originally discharges low-temperature air at the outlet side of the expander in the freezer, and is not a closed-type device, but maintains the compressor suction pressure at around atmospheric pressure. In view of this, it is possible to solve the problem that a closed type device and an open type device can be used in a single model in terms of pressure.
However, in the above apparatus, since the dry air introduction part and the air discharge path are provided on the suction side of the compressor for pressure adjustment, the air pressure to be introduced and the air pressure to be released are easily balanced, and smooth pressure control is difficult. It is easy to become.
Further, in a closed refrigeration apparatus, for example, in Patent Document 2, a technique for introducing dry air having a dew point of about −30 ° C. into a compressor suction path that forms a refrigerant gas circulation path from a refrigerant gas replenishment apparatus via an introduction path. Is disclosed.

JP 2004-317081 A Japanese Patent Laid-Open No. 10-47829

The apparatus disclosed in Patent Document 2 introduces dry air having a dew point of about −30 ° C. into the compressor suction path, and then fills the refrigerant gas circulation path to a predetermined pressure, for example, about 1 kg / cm 2 G. Although it is a closed type device that starts the compressor after being pressurized (see paragraph [0019]), as disclosed in paragraph [0008], an operation for cooling the regenerator material with the refrigerant gas, and the circulating refrigerant Is applied to a special refrigeration device that performs the operation of freezing the object to be frozen at the same time or at different times, and only discloses that dry air is introduced before starting the compressor, There is no description of adjusting the side pressure.

An object of the present invention is to realize a closed-type gas circulation type refrigeration apparatus that can adjust the compressor suction side pressure with a simple and low-cost apparatus configuration in view of the problems of the prior art. To do.

In order to achieve such an object, a closed-type gas circulation refrigeration apparatus of the present invention includes a compressor and an expander connected to a single output shaft of a drive device, a cooler that cools a compressor discharge side refrigerant gas, A brine cooler that cools a brine that cools an object to be cooled with a refrigerant gas composed of air or nitrogen gas, and a cold recovery heat exchanger that further cools the refrigerant gas cooled by the cooler with a return refrigerant gas from the brine cooler An expansion tank in which a refrigerant gas having a pressure higher than atmospheric pressure and less than 0.2 MPa (gauge pressure), which is a pressure outside the high-pressure gas safety method, is enclosed, A closed-system refrigerant gas supply / discharge device comprising a compressor suction-side connection path that connects a tank and a compressor suction-side refrigerant gas path, and a compressor discharge-side connection path that connects an expansion tank and a compressor discharge-side refrigerant gas path A pressure sensor for detecting the pressure of the refrigerant gas flowing through the compressor suction side refrigerant gas path, and detecting the refrigerant gas pressure in the compressor suction side refrigerant gas path from the expansion tank while detecting the refrigerant gas pressure in the compressor suction side refrigerant gas path Refrigerant gas supply to the refrigerant gas passage and discharge of refrigerant gas from the compressor discharge side refrigerant gas passage to the expansion tank, so that the refrigerant gas pressure in the compressor suction side refrigerant gas passage is maintained within a set range. It is composed.

In the device of the present invention, even in a closed type device provided with the above-described closed system refrigerant gas supply / exhaust device without an open port to the outside, replenishment of refrigerant gas from the expansion tank to the compressor suction side refrigerant gas path; In order to discharge the refrigerant gas from the refrigerant gas path on the compressor discharge side to the expansion tank, the replenishment and expansion of the refrigerant gas from the expansion tank is ensured by using the pressure difference between the compressor discharge side and the suction side. The refrigerant gas can be discharged to the tank.
In addition, since the supply and discharge of the refrigerant gas is a closed circulation path via the expansion tank, the refrigerant gas pressure in the compressor suction side refrigerant gas path is maintained while maintaining the closed circulation system without unnecessary refrigerant gas being released into the atmosphere. Can be adjusted. As a result, the expansion tank can be kept below 0.2 MPa (gauge pressure), which is the pressure outside the high-pressure gas safety method.
As a result, even a closed type device can be used as a device having the same design specifications (such as pressure) as that of an open type device, and the cost can be reduced.

Also, the refrigerant gas is not released to the outside. Therefore, the wear of the refrigerant gas is eliminated, and the external air is not mixed into the refrigerant gas path, so that the moisture of the external air is not mixed into the refrigerant gas. Therefore, if the expansion tank is filled with dry air or nitrogen gas having a dew point lower than the operating temperature of the refrigeration system, it can always be operated at a temperature higher than the dew point temperature of the refrigerant gas, so a dehumidifier is not required and the refrigerant gas The problem of increased pressure loss in the refrigerant gas flow path due to freezing of the contained water does not occur. Furthermore, wear of the refrigerant gas can be suppressed by using the closed system refrigerant gas supply / discharge device.

In addition, the refrigerant gas pressure in the expansion tank is maintained at a pressure higher than the refrigerant gas pressure in the compressor suction side refrigerant gas path, and at a pressure lower than the refrigerant gas pressure in the compressor discharge side refrigerant gas path and not applicable to the high pressure gas safety method. If it is less than a certain 0.2 MPa (gauge pressure), even a closed type device having the same design specifications as the open type device is low-cost and refrigerant from the expansion tank to the compressor suction side refrigerant gas path The gas supply and the discharge of the refrigerant gas from the compressor discharge side refrigerant gas passage to the expansion tank can be performed smoothly.

In the present invention, the first on-off valve provided in the compressor suction side connection path, the second on-off valve provided in the compressor discharge side connection path, the detection signal of the pressure sensor is input, the first on-off valve, And a controller that operates the second on-off valve to maintain the refrigerant gas pressure in the suction side refrigerant gas passage within a set range.

In such a configuration, when the detected value of the pressure sensor falls below the set range during operation of the apparatus, the first on-off valve is opened, the refrigerant gas is supplied to the compressor suction side refrigerant gas passage, and the detected value of the pressure sensor is set. If it exceeds the range, the second on-off valve opens, and excess refrigerant gas is recovered from the refrigerant gas passage to the expansion tank. As a result, the refrigerant gas pressure in the refrigerant gas passage can be accurately maintained within the set range.

In the apparatus of the present invention, the expansion tank contains a hollow stretchable body in which gas is sealed inside a stretchable hollow hermetic membrane, and the hollow stretchable body is placed in accordance with the refrigerant gas pressure in the compressor suction side refrigerant gas path. The refrigerant gas pressure in the compressor suction side refrigerant gas passage may be configured to be expanded and contracted to be maintained within a set range. As a result, when the refrigerant gas pressure in the compressor suction side refrigerant gas path falls below the set range, the hollow expandable body automatically expands and supplies the refrigerant gas to the compressor suction side refrigerant gas path. Conversely, if the compressor suction side refrigerant gas pressure rises above the set range, the refrigerant gas around the hollow stretchable body compresses the hollow stretchable body, so that the hollow stretchable body automatically contracts and the compressor suction side refrigerant is compressed. Recover the refrigerant gas from the gas path.

With this configuration, it is not necessary to provide a pressure reducing valve or an on-off valve in the compressor suction side refrigerant gas passage, and the refrigerant gas pressure in the refrigerant gas passage is kept within a set range without requiring complicated control such as valve operation. Can be maintained. Moreover, the compressor suction side refrigerant gas pressure can be automatically set by predetermining the gas pressure of the hollow stretchable body in accordance with the size of the expansion tank.

The operation method of the present invention using the apparatus of the present invention includes a step of detecting a refrigerant gas pressure in the suction side refrigerant gas path with a pressure sensor, and a suction side refrigerant from the expansion tank when the refrigerant gas pressure falls below a set range. Supplying the refrigerant gas to the gas passage and returning the refrigerant gas pressure to the set range; and when the refrigerant gas pressure exceeds the set range, discharging the refrigerant gas from the discharge side refrigerant gas passage to the expansion tank, Returning the refrigerant gas pressure in the refrigerant gas path to the set range.

In the method of the present invention, the refrigerant gas is supplied / discharged between the closed system refrigerant gas supply / discharge device and the closed type refrigerant gas passage via the expansion tank, so that the compressor suction side refrigerant gas pressure is adjusted. It becomes possible. As a result, the expansion tank can be kept below 0.2 MPa (gauge pressure), which is the pressure outside the high-pressure gas safety method. Further, wear due to the release of the refrigerant gas to the atmosphere (external) is eliminated, and the external air is not mixed into the refrigerant gas path. Therefore, if the dry gas is sealed in the expansion tank, the moisture of the external air is not mixed in the refrigerant gas, so that the operation can always be performed at or above the outdoor temperature of the refrigerant gas. Therefore, no dehumidifier is required. Further, since the sealed refrigerant gas supply / discharge device is used, there is no wear of the refrigerant gas.

According to the present invention, the feature is that the refrigerant gas pressure in the expansion tank is higher than the refrigerant gas pressure in the compressor suction side refrigerant gas passage and lower than the refrigerant gas pressure in the compressor discharge side refrigerant gas passage (0.2 MPa (gauge). Pressure))), the refrigerant gas pressure in the compressor suction-side refrigerant gas passage can be adjusted smoothly, and it is not necessary to install a dehumidifier. Supply and discharge can be performed smoothly. Moreover, even a closed-type device can be used as a device having the same design specifications (such as pressure) as an open-type device, and the expansion tank is kept below 0.2 MPa (gauge pressure), which is a pressure not applied to the high-pressure gas safety law. Can be low cost.

1 is a system diagram of a closed air refrigerant refrigeration apparatus according to a first embodiment in which the present invention is applied to an air refrigerant refrigeration apparatus. It is a system diagram of a closed type air refrigerant refrigeration apparatus according to a second embodiment in which the present invention is applied to an air refrigerant refrigeration apparatus.

Hereinafter, the present invention will be described in detail using embodiments shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in this embodiment are not intended to limit the scope of the present invention to that unless otherwise specified.

(Embodiment 1)
A first embodiment in which the present invention is applied to an air refrigerant refrigeration apparatus will be described with reference to FIG. In the closed-type air refrigerant refrigeration apparatus 10A according to the present embodiment shown in FIG. 1, refrigerant air passages 12a to 12f through which refrigerant air circulates are provided. A type heat exchanger 16, a heat recovery heat exchanger 18, and a brine cooler 20 are provided. The compression / expansion unit 14 includes a compressor 22, a motor 24, and an expander 26. The compressor 22 and the expander 26 are coupled to a rotating shaft 24a of the motor 24 and rotate coaxially.

The compressor discharge side refrigerant air passage 12 b connected to the discharge port of the compressor 22 is connected to the inlet of the high temperature side passage of the water-cooled heat exchanger 16. The outlet of the high temperature side passage is connected to the refrigerant air passage 12c, and the other end of the refrigerant air passage 12c is connected to the inlet of the high temperature side passage of the heat recovery heat exchanger 18. The outlet of the high temperature side passage is connected to the refrigerant air passage 12d, and the other end of the refrigerant air passage 12d is connected to the inlet of the expander 26.

The outlet of the expander 26 is connected to the refrigerant air passage 12e, and the other end of the refrigerant air passage 12e is connected to the inlet of the brine cooler 20. The refrigerant air passage 12 f is connected to the outlet of the brine cooler 20, and the other end of the refrigerant air passage 12 f is connected to the inlet of the low temperature side passage of the heat recovery heat exchanger 18. The outlet of the low temperature side flow path is connected to the compressor suction side refrigerant air path 12 a, and the other end of the compressor suction side refrigerant air path 12 a is connected to the suction port of the compressor 22.

A cooling water circulation path 28 is connected to the inlet and outlet of the low temperature side channel of the water-cooled heat exchanger 16. The cooling water circulation path 28 is provided with a cooling tower 30, a pump 32, and a flow rate adjusting valve 34. The cooling water is cooled by the cooling tower 30 and circulated in the direction of the arrow by the pump 32. The cooling water circulation path 28 is appropriately supplemented with makeup water c such as well water and industrial water.
A brine circulation path 36 is disposed inside the brine cooler 20. The brine circulation path 36 is connected to a heat exchange pipe 38 disposed inside the freezer 40.

In addition, a sealed expansion tank 51 is provided that encloses refrigerant air at a pressure equal to or higher than atmospheric pressure and has no open port to the outside. The expansion tank 51 and the compressor suction side refrigerant air passage 12a communicate with each other through a compressor suction side connection (replenishment) passage 52, and the expansion tank 51 and the compressor discharge side refrigerant air passage 12b connect to the compressor discharge side connection ( (Recovery) Communicating through a path 54. The compressor suction side connection (replenishment) path 52 is provided with a pressure reducing valve 56 and an electromagnetic valve 58, and the compressor discharge side connection (recovery) path 54 is provided with an electromagnetic valve 60. The expansion tank 51 is filled with dry air or nitrogen gas having a dew point lower than the operating temperature condition of the refrigeration apparatus. The pressure in the expansion tank 51 is set higher than the refrigerant air pressure in the compressor suction side refrigerant air passage 12a and lower than the refrigerant air pressure in the compressor discharge side refrigerant air passage 12b.

Further, a pressure sensor 62 for detecting refrigerant air pressure is provided in the compressor suction side refrigerant air passage 12a. The controller 64 inputs the detection signal of the pressure sensor 62 and controls the opening / closing operation of the electromagnetic valves 58 and 60. The expansion tank 51, the compressor suction side connection path 52, the compressor discharge side connection path 54, and the devices equipped thereto constitute a closed system refrigerant air supply / discharge device 50.

In such a configuration, the refrigerant air is compressed by the compressor 22 and discharged at a high temperature and a high pressure. The refrigerant air that has become high temperature and pressure is primarily cooled by cooling water in the water-cooled heat exchanger 16. The primary cooled refrigerant air is secondarily cooled by the refrigerant air returned from the brine cooler 20 in the heat recovery heat exchanger 18. The secondary-cooled refrigerant air is expanded by the expander 26 and becomes cryogenic and low-pressure refrigerant air.

The low-temperature and low-pressure refrigerant air is supplied to the brine cooler 20 through the refrigerant gas passage 12e, and the brine cooler 20 exchanges heat with the brine circulating in the brine circulation passage 36, thereby cooling the brine. The cooled brine is sent to the heat exchange pipe 38 in the freezer 40, and the atmosphere in the freezer 40 is cooled to, for example, −50 ° C. to −100 ° C. As a result, the object to be cooled such as food stored in the freezer 40 is stored frozen. The refrigerant air after being used for cooling the brine by the brine cooler 20 reaches the heat recovery heat exchanger 18 via the refrigerant air passage 12f. The heat recovery heat exchanger 18 exchanges heat with the refrigerant air before being sent to the expander 26, cools the refrigerant air, and then passes through the compressor suction side refrigerant air passage 12a to the suction port of the compressor 22. Sent.

When the operation of the closed-type air refrigerant refrigeration apparatus 10A is started, the refrigerant air in the refrigerant air passages 12d to 12f gradually cools, and at the same time, the volume of the refrigerant air decreases, and the density increases as the volume decreases. I will do it. For this reason, the refrigerant air pressure in the refrigerant air passages 12a, 12e, and 12f gradually decreases, becomes negative in the compressor suction side refrigerant air passage 12a, and falls below the set range. Therefore, this is detected by the pressure sensor 62 and the electromagnetic valve 58 is opened by the controller 64. As a result, the refrigerant air sealed in the expansion tank 51 is supplied to the compressor suction side refrigerant air path 12a via the compressor suction side connection (replenishment) path 52, and the refrigerant air pressure in the compressor suction side refrigerant air path 12a is reduced. Return to the setting range.

Also, if the refrigerant air pressure in the compressor suction side refrigerant air passage 12a rises due to an increase in the ambient temperature of the refrigeration system, the operation may not be started. Therefore, when the refrigerant air pressure exceeds the set range, this is detected by the pressure sensor 62 and the electromagnetic valve 60 is opened by the controller 64. As a result, the refrigerant air in the compressor discharge side refrigerant air passage 12b is returned to the expansion tank 51 via the compressor discharge side connection (collection) passage 54, and the refrigerant air pressure in the compressor suction side refrigerant air passage 12a is returned to the set range. .

According to the present embodiment, the refrigerant air pressure of the compressor suction side refrigerant air passage 12a of the closed-type air refrigerant refrigeration apparatus 10A can be adjusted within a set range, so that switching to an open-type air refrigerant refrigeration apparatus is possible. become. Therefore, one air refrigerant type refrigeration device can be used as both a closed type and an open type air refrigerant type refrigeration device, and the expansion tank 51 is 0.2 MPa (gauge pressure), which is a pressure not applied to the high-pressure gas safety method. Since it can hold below, it becomes low-cost.

Further, since the refrigerant air is supplied and discharged between the closed-system refrigerant air supply / discharge device 50 and the compressor suction-side refrigerant air passage 12a, the refrigerant air is not worn and the external air is not mixed into the refrigerant gas. Since there is no moisture in the external air in the refrigerant gas, it can always be operated above the outdoor temperature of the refrigerant gas. Therefore, no dehumidifier is required. Furthermore, since the refrigerant air is not released to the outside, the refrigerant air is not worn.

Further, the refrigerant air is supplied from the expansion tank 51 to the low-pressure compressor suction-side refrigerant air passage 12a, and the refrigerant air in the compressor discharge-side refrigerant gas passage 12b is connected to the compressor discharge-side connection from the compressor discharge-side refrigerant air passage 12b ( Since the refrigerant is discharged to the low-pressure expansion tank 51 via the recovery) passage 54, the refrigerant air can be smoothly supplied and discharged from these refrigerant air passages.
Further, the refrigerant air pressure in the compressor suction side refrigerant air passage 12a is detected by the pressure sensor 62, and the electromagnetic valves 58 and 60 are opened and closed by the controller 64 so that the detected pressure value falls within the set range. The refrigerant air pressure in the refrigerant air passage 12a can be accurately maintained within the set range.

In this embodiment, air is used as the refrigerant gas, but nitrogen gas may be used instead of air. In this case, nitrogen gas is sealed in the expansion tank 51.
Further, the controller 64 controls the opening degree of the flow rate adjusting valve 34 to adjust the flow rate of the cooling water flowing through the cooling water circulation path 28, thereby adjusting the cooling capacity of the water-cooled heat exchanger 16. .

(Embodiment 2)
Next, a second embodiment in which the present invention is applied to an air refrigerant refrigeration apparatus will be described with reference to FIG. In the closed-type air refrigerant refrigeration apparatus 10B of the present embodiment, a hollow elastic body 74 in which a gas g is enclosed in an expansion / contraction hollow sealed membrane inside an expansion tank 72 constituting the closed-system refrigerant air supply / exhaust device 70. Built in. The sealing film may be made of, for example, rubber, and air or nitrogen gas can be used as the gas g enclosed in the hollow stretchable body 74.

Further, in the closed system refrigerant air supply / exhaust device 70 of the present embodiment, the pressure reducing valve 56 and the electromagnetic valve 58 of the first embodiment are removed from the suction side connection path 52, and the controller 64 inputs a detection signal of the pressure sensor 62. The electromagnetic valve 60 is opened and closed according to the detection signal. Other configurations are the same as those of the first embodiment.

In the present embodiment, when the refrigerant air in the compressor suction side refrigerant air passage 12a decreases, the hollow sealed membrane 72 automatically expands, and the compressor suction side refrigerant passes through the compressor suction side connection (replenishment) passage 52. Refrigerant air is supplied to the air passage 12a. Conversely, if the refrigerant air pressure in the compressor suction side refrigerant air passage 12a rises, the refrigerant air around the telescopic hollow body 74 presses the telescopic hollow body 74 from the outside, so the telescopic hollow body 74 automatically contracts. Then, the refrigerant air is recovered from the compressor suction side refrigerant air passage 12a.

When the refrigerant air pressure in the compressor suction side refrigerant air passage 12 a exceeds the set range even by the expansion and contraction of the hollow elastic body 74, the electromagnetic valve 60 is opened by the controller 64 and the compressor discharge side connection (collection) passage 54 is connected. It collect | recovers to the hollow expansion-contraction body 74, and returns the refrigerant | coolant air pressure of the compressor suction side refrigerant | coolant air path 12a to a setting range.

According to such a configuration, as in the first embodiment, in addition to being able to adjust the refrigerant air pressure of the compressor suction side refrigerant air passage 12a, a pressure reducing valve and an on-off valve are provided in the compressor suction side refrigerant air passage 12a. Need not be provided. Therefore, since complicated control for operation of these valves is not required, there is an advantage that the closed-system refrigerant air supply / exhaust device 70 can be reduced in cost. Further, by predetermining the gas pressure of the hollow stretchable body 74 according to the size of the expansion tank 72, the refrigerant air pressure of the compressor suction side refrigerant air passage 12a can be automatically set.

According to the present invention, the refrigerant gas pressure in the expansion tank is less than 0.2 MPa (gauge pressure), which is higher than the refrigerant gas pressure in the compressor suction side refrigerant gas path and lower than the refrigerant gas pressure in the compressor discharge side refrigerant gas path. By holding the refrigerant gas in the low-cost closed-type gas circulation refrigeration apparatus, the refrigerant gas pressure in the compressor suction-side refrigerant gas passage can be adjusted.

Claims (4)

The compressor and the expander connected to the single output shaft of the driving device, the cooler for cooling the compressor discharge side refrigerant gas, and the brine for cooling the cooling object with the refrigerant gas composed of air or nitrogen gas are cooled. In a closed gas circulation refrigeration apparatus comprising a brine cooler and a cold recovery heat exchanger that further cools the refrigerant gas cooled by the cooler with a return refrigerant gas from the brine cooler,
An expansion tank filled with a refrigerant gas having a pressure higher than atmospheric pressure and less than 0.2 MPa (gauge pressure) that is not applicable to the High Pressure Gas Safety Law, and the expansion tank and the compressor suction side refrigerant gas passage are connected A closed-system refrigerant gas supply / discharge device comprising a compressor suction-side connection path, a compressor discharge-side connection path connecting the expansion tank and the compressor discharge-side refrigerant gas path, and a refrigerant flowing through the compressor suction-side refrigerant gas path A pressure sensor for detecting the pressure of the gas,
Supply of refrigerant gas from the expansion tank to the compressor suction side refrigerant gas path via the compressor suction side connection path, while detecting the refrigerant gas pressure of the compressor suction side refrigerant gas path with the pressure sensor; The refrigerant gas is discharged from the discharge side refrigerant gas path to the expansion tank via the compressor discharge side connection path, and the refrigerant gas pressure of the compressor suction side refrigerant gas path is maintained within a set range. A closed-type gas circulation refrigeration device. The first on-off valve provided in the compressor suction side connection path, the second on-off valve provided in the compressor discharge side connection path, and the detection signal of the pressure sensor are input, and the first on-off valve and the first on-off valve 2. A closed-type gas circulation refrigeration apparatus according to claim 1, further comprising: a controller that operates the two on-off valves to maintain the refrigerant gas pressure in the compressor suction side refrigerant gas passage within a set range. The expansion tank incorporates a hollow stretchable body in which gas is sealed inside a stretchable hollow hermetic membrane, and the hollow stretchable body is stretched and compressed according to the refrigerant gas pressure in the refrigerant gas passage on the compressor suction side. 2. The closed-type gas circulation type refrigeration apparatus according to claim 1, wherein the refrigerant gas pressure of the machine suction side refrigerant gas passage is held within a set range. In the operation method of the closed-type gas circulation type refrigeration apparatus according to claim 1,
Detecting the refrigerant gas pressure in the compressor suction side refrigerant gas path with the pressure sensor;
When the refrigerant gas pressure falls below a set range, supplying refrigerant gas from the expansion tank to the compressor suction side refrigerant gas path via the compressor suction side connection path, and returning the refrigerant gas pressure to the set range; ,
When the refrigerant gas pressure exceeds the set range, the refrigerant gas is discharged from the compressor discharge side refrigerant gas passage to the expansion tank via the compressor discharge side connection passage, and the refrigerant gas pressure in the compressor suction side refrigerant gas passage is reduced. And a step of returning to a set range.

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