JP2024049917A - Secondary refrigerant refrigeration system and method for adjusting pressure of secondary refrigerant - Google Patents

Abstract

[Problem] To adjust the pressure of a load-side evaporator in a load-side secondary refrigerant circuit. [Solution] A secondary refrigerant refrigeration system according to at least one embodiment of the present disclosure includes a primary refrigerant circuit in which a primary refrigerant circulates and in which a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator are arranged, a load-side secondary refrigerant circuit including a load-side evaporator and circulating the load-side secondary refrigerant to the load-side evaporator and the primary refrigerant evaporator, a condensing-side secondary refrigerant circuit including a condensing-side condenser and circulating a condensing-side secondary refrigerant that is the same refrigerant as the load-side secondary refrigerant to the condensing-side condenser and the primary refrigerant condenser, and a gas-phase portion connection flow path that connects a gas-phase portion of the load-side secondary refrigerant circuit to a gas-phase portion of the condensing-side secondary refrigerant circuit. [Selected Figure] FIG.

Description

The present disclosure relates to a secondary refrigerant refrigeration system and a method for adjusting the pressure of a secondary refrigerant.

A secondary refrigerant refrigeration system is known that includes a primary refrigerant circuit that includes an evaporator and through which a primary refrigerant circulates, and a secondary refrigerant circuit that supplies the secondary refrigerant cooled by the primary refrigerant in the evaporator to a cooling load (see, for example, Patent Document 1).

JP 2012-007757 A

It is desirable to control the pressure of the secondary refrigerant in an evaporator that mainly uses the latent heat of the secondary refrigerant for cooling, such as in the secondary refrigerant refrigeration system described in Patent Document 1. For example, in order to perform defrosting in the evaporator, it is conceivable to increase the pressure of the secondary refrigerant in the evaporator and condense the secondary refrigerant in the evaporator at a temperature of 0° C. or higher.
Furthermore, when the pressure of the secondary refrigerant in the evaporator increases due to an unintended increase in the cooling load or the like, it is necessary to reduce the pressure of the secondary refrigerant in the evaporator.

In view of the above circumstances, at least one embodiment of the present disclosure aims to adjust the pressure of the load-side evaporator in the load-side secondary refrigerant circuit.

(1) A secondary refrigerant refrigeration system according to at least one embodiment of the present disclosure,
a primary refrigerant circuit in which a primary refrigerant circulates and in which a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator are disposed;
A load side secondary refrigerant circuit including a load side evaporator and circulating a load side secondary refrigerant through the load side evaporator and the primary refrigerant evaporator;
a condensation-side secondary refrigerant circuit including a condensation-side condenser and circulating a condensation-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, through the condensation-side condenser and the primary refrigerant condenser;
A gas phase portion connecting flow path connecting a gas phase portion of the load side secondary refrigerant circuit and a gas phase portion of the condensation side secondary refrigerant circuit;
Equipped with.

(2) A method for adjusting a pressure of a secondary refrigerant according to at least one embodiment of the present disclosure,
A method for adjusting pressure of a secondary refrigerant in a secondary refrigerant refrigeration system, comprising:
The secondary refrigerant refrigeration system comprises:
a primary refrigerant circuit in which a primary refrigerant circulates and in which a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator are disposed;
A load side secondary refrigerant circuit including a load side evaporator and circulating a load side secondary refrigerant through the load side evaporator and the primary refrigerant evaporator;
a condensation-side secondary refrigerant circuit including a condensation-side condenser and circulating a condensation-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, through the condensation-side condenser and the primary refrigerant condenser;
A gas phase portion connecting flow path connecting a gas phase portion of the load side secondary refrigerant circuit and a gas phase portion of the condensation side secondary refrigerant circuit;
Equipped with
The pressure of the load side evaporator is adjusted by supplying secondary refrigerant from either the load side secondary refrigerant circuit or the condensation side secondary refrigerant circuit to the other secondary refrigerant circuit via the gas phase section connection flow path.

According to at least one embodiment of the present disclosure, the pressure of the load side evaporator in the load side secondary refrigerant circuit can be adjusted.

FIG. 1 is a schematic diagram of a secondary refrigerant refrigeration system according to some embodiments. FIG. 13 is a diagram for explaining transfer of secondary refrigerant liquid using an intermediate refrigerant tank.

Hereinafter, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present disclosure.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only express such a configuration strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

Figure 1 is a system diagram of a secondary refrigerant refrigeration system according to some embodiments. The secondary refrigerant refrigeration system 1 according to some embodiments includes a primary refrigerant circuit 10, a load side secondary refrigerant circuit 30, and a condensation side secondary refrigerant circuit 50.

(Primary refrigerant circuit 10)
In the secondary refrigerant refrigeration system 1 according to some embodiments, the primary refrigerant circuit 10 is a refrigerant circuit that includes a primary refrigerant compressor 11, a primary refrigerant condenser 13, an expansion valve 15, and a primary refrigerant evaporator 17, and that constitutes a refrigeration cycle in which the primary refrigerant circulates. In the primary refrigerant circuit 10, the primary refrigerant compressed by the primary refrigerant compressor 11 is sent to the primary refrigerant condenser 13 that functions as a condenser of the primary refrigerant circuit 10. In the primary refrigerant condenser 13, the primary refrigerant is cooled and condensed by the condensation-side secondary refrigerant of the condensation-side secondary refrigerant circuit 50. The condensed primary refrigerant liquid is reduced in pressure through the expansion valve 15 and sent to the primary refrigerant evaporator 17 that functions as an evaporator of the primary refrigerant circuit 10. In the primary refrigerant evaporator 17, the primary refrigerant liquid absorbs heat from the load-side secondary refrigerant of the load-side secondary refrigerant circuit 30 and vaporizes. The vaporized primary refrigerant is compressed again by the primary refrigerant compressor 11.

In some embodiments of the secondary refrigeration system 1, the primary refrigerant may be of any composition.
In some embodiments of the secondary refrigerant refrigeration system 1 , the primary refrigerant circuit 10 is located, for example, in the chiller 3 .

(Load side secondary refrigerant circuit 30)
In the secondary refrigerant refrigeration system 1 according to some embodiments, the load side secondary refrigerant circuit 30 is a refrigerant circuit in which a load side secondary refrigerant tank 31, a refrigerant pump 33, and a load side evaporator 35 are arranged, the load side secondary refrigerant circulates, and latent heat exchange is performed in the load side evaporator 35. In the load side secondary refrigerant circuit 30, the load side secondary refrigerant liquid from the load side secondary refrigerant tank 31 is sent by the refrigerant pump 33 to the load side evaporator 35 that functions as an evaporator of the load side secondary refrigerant circuit 30. In the secondary refrigerant refrigeration system 1 shown in FIG. 1, the number of load side evaporators 35 arranged in parallel in the load side secondary refrigerant circuit 30 is three, but may be two or less, or may be four or more.
For ease of explanation, it is assumed that one of the three load side evaporators 35 is a first load side evaporator 35A, another is a second load side evaporator 35B, and still another is a third load side evaporator 35C.

In the load side evaporator 35, at least a part of the load side secondary refrigerant liquid is vaporized by latent heat exchange with the object to be cooled, and flows out of the load side evaporator 35 in a gas-liquid mixed state. In the secondary refrigerant refrigeration system 1 shown in Figure 1, when the load side evaporator 35 is used to cool the air in a refrigerated warehouse, for example, the load side evaporator 35 is an air cooler.
The load side secondary refrigerant in a gas-liquid mixed state flowing out of the load side evaporator 35 is sent to the load side secondary refrigerant tank 31. In the load side secondary refrigerant tank 31, the load side secondary refrigerant is separated into gas and liquid, and the gas phase load side secondary refrigerant is cooled by the primary refrigerant of the primary refrigerant circuit 10 in the primary refrigerant evaporator 17 and liquefied, and returns to the load side secondary refrigerant tank 31. The liquefied load side secondary refrigerant is sent to the load side evaporator 35 by the refrigerant pump 33.
In addition, the load side secondary refrigerant circuit 30 in the present invention includes a line in which the load side secondary refrigerant liquid is sent from the load side secondary refrigerant tank 31 to the load side evaporator 35 by the refrigerant pump 33, where a portion of it vaporizes and becomes a gas-liquid mixed state and returns to the load side secondary refrigerant tank 31, and a line in which the gas phase load side secondary refrigerant is cooled by the primary refrigerant of the primary refrigerant circuit 10 from the load side secondary refrigerant tank 31 and liquefied, and returns to the load side secondary refrigerant tank 31.

In the load side secondary refrigerant circuit 30 according to some embodiments, the load side secondary refrigerant tank 31 is provided with a level sensor 61 for detecting the liquid level of the load side secondary refrigerant in the load side secondary refrigerant tank 31. Also, in the load side secondary refrigerant circuit 30 according to some embodiments, each load side evaporator 35 is provided with an inlet side shutoff valve 71 capable of closing the inlet side refrigerant flow path 37i connected to the inlet of the load side evaporator 35, and an outlet side shutoff valve 72 capable of closing the outlet side refrigerant flow path 37o connected to the outlet of the load side evaporator 35.
During normal operation of the load side secondary refrigerant circuit 30, each of the inlet side shut-off valves 71 and each of the outlet side shut-off valves 72 are open.

In some embodiments, the load side secondary refrigerant circuit 30 is provided with a pressure sensor 62 for detecting the pressure of the load side secondary refrigerant in the refrigerant flow path 38 downstream of each outlet side shutoff valve 72 and upstream of the load side secondary refrigerant tank 31.

(Condensation side secondary refrigerant circuit 50)
In the secondary refrigerant refrigeration system 1 according to some embodiments, the condensation side secondary refrigerant circuit 50 is a refrigerant circuit in which a condensation side secondary refrigerant tank 51, a refrigerant pump 53, and a condensation side condenser 55 are arranged, the condensation side secondary refrigerant circulates, and latent heat exchange is performed in the condensation side condenser 55. In the condensation side secondary refrigerant circuit 50, the condensation side secondary refrigerant liquid from the condensation side secondary refrigerant tank 51 is sent to the primary refrigerant condenser 13 by the refrigerant pump 53. In the primary refrigerant condenser 13, the condensation side secondary refrigerant liquid absorbs heat from the primary refrigerant of the primary refrigerant circuit 10 and vaporizes. The vaporized condensation side secondary refrigerant is sent to the condensation side condenser 55. In the condensation side condenser 55, the condensation side secondary refrigerant is cooled by outside air blown by the cooling fan 57 and liquefied. The liquefied condensation side secondary refrigerant returns to the condensation side secondary refrigerant tank 51.

In some embodiments of the condensation side secondary refrigerant circuit 50, the condensation side secondary refrigerant tank 51 is provided with a level sensor 63 for detecting the liquid level of the condensation side secondary refrigerant in the condensation side secondary refrigerant tank 51.

In some embodiments of the secondary refrigerant refrigeration system 1, the load side secondary refrigerant and the condensation side secondary refrigerant are the same refrigerant. That is, the components of the load side secondary refrigerant are the same as the components of the condensation side secondary refrigerant. For example, if the load side secondary refrigerant is _CO2 refrigerant, the condensation side secondary refrigerant is _CO2 refrigerant; for example, if the load side secondary refrigerant is _NH3 refrigerant, the condensation side secondary refrigerant is _NH3 refrigerant; for example, if the load side secondary refrigerant is R134a, the condensation side secondary refrigerant is R134a.
In the following description, the load side secondary refrigerant and the condensation side secondary refrigerant will also be simply referred to as the secondary refrigerant when there is no need to particularly distinguish between the load side secondary refrigerant and the condensation side secondary refrigerant.

(Gas phase section connection flow path 81)
In some embodiments, the secondary refrigerant refrigeration system 1 is provided with a gas phase section connection flow path 81 that connects a gas phase section 32 (hereinafter also simply referred to as the "gas phase section 32") including a gas-liquid mixed state of the load side secondary refrigerant circuit 30 and a gas phase section 52 of the condensation side secondary refrigerant circuit 50.
The gas phase connection passage 81 is connected to the load side secondary refrigerant circuit 30, for example to each load side evaporator 35, via a first opening/closing valve 73 to the outlet side refrigerant passage 37o between the outlet of the load side evaporator 35 and the outlet side shut-off valve 72.
With respect to the load side secondary refrigerant circuit 30, the gas phase connection flow path 81 is preferably connected via the second opening/closing valve 74 to a refrigerant flow path 38 downstream of each outlet side shut-off valve 72 and upstream of the load side secondary refrigerant tank 31, but it may also be connected to the refrigerant flow path 40 that connects the gas phase portion 39 of the load side secondary refrigerant circuit 30, i.e., the gas phase portion of the load side secondary refrigerant tank 31 and the primary refrigerant evaporator 17.
The gas phase section connecting flow passage 81 is connected to the refrigerant flow passage 56 downstream of the primary refrigerant condenser 13 and upstream of the condensation side condenser 55 with respect to the condensation side secondary refrigerant circuit 50 , for example.
During normal operation of the load side secondary refrigerant circuit 30, the first on-off valves 73 and the second on-off valves 74 are each closed.
The function of the gas phase section connecting flow path 81 will be described in detail later.

(Liquid phase section connecting flow path 83)
In some embodiments, the secondary refrigerant refrigeration system 1 is provided with a liquid phase section connecting flow path 83 that connects the liquid phase section 34 of the load side secondary refrigerant circuit 30 and the liquid phase section 54 of the condensation side secondary refrigerant circuit 50.
In the secondary refrigerant refrigeration system 1 shown in FIG. 1, the liquid phase section connecting flow path 83 includes, for example, a first liquid phase section connecting flow path 83A and a second liquid phase section connecting flow path 83B.
The first liquid phase part connecting flow path 83A and the second liquid phase part connecting flow path 83B are connected to the load side secondary refrigerant tank 31 of the load side secondary refrigerant circuit 30.
Furthermore, the first liquid phase part connecting flow path 83A and the second liquid phase part connecting flow path 83B are connected to a condensation side secondary refrigerant tank 51 with respect to the condensation side secondary refrigerant circuit 50 .
The first liquid phase section connecting flow path 83A is provided with a liquid return pump 84 for sending secondary refrigerant liquid from the load side secondary refrigerant tank 31 to the condensation side secondary refrigerant tank 51, a first pump valve 75, and a second pump valve 79. The first pump valve 75 is provided on the discharge side of the liquid return pump 84, and the second pump valve 79 is provided on the suction side of the liquid return pump 84.
The second liquid phase section connecting flow path 83B is provided with a liquid return valve 76 for returning the secondary refrigerant liquid from the condensation side secondary refrigerant tank 51 to the load side secondary refrigerant tank 31.

In addition, the secondary refrigerant refrigeration system 1 shown in Figure 1 is provided with a connection flow path 85 that connects the first liquid phase section connection flow path 83A and the second liquid phase section connection flow path 83B, and a discharge flow path 86 that connects the first liquid phase section connection flow path 83A downstream of the liquid return pump 84 and the load side secondary refrigerant tank 31.
The connection flow path 85 connects the second liquid phase part connection flow path 83B between the condensation side secondary refrigerant tank 51 and the liquid return valve 76, and the first liquid phase part connection flow path 83A between the second pump valve 79 and the liquid return pump 84. The connection flow path 85 is provided with a connection valve 77.

The discharge flow path 86 connects the first liquid phase connection flow path 83A between the liquid return pump 84 and the first pump valve 75 to the load side secondary refrigerant tank 31. The discharge flow path 86 is provided with a third pump valve 78.

During normal operation of the secondary refrigerant refrigeration system 1, the first pump valve 75, the second pump valve 79, the third pump valve 78, the connection valve 77, and the liquid return valve 76 are all closed, and the liquid return pump 84 is stopped.

A secondary refrigerant refrigeration system 1 according to some embodiments includes a control device 90 for controlling each part of the secondary refrigerant refrigeration system 1. The control device 90 includes a processor 91 that executes various arithmetic processing, and a memory 93 that non-temporarily or temporarily stores various data processed by the processor 91. The processor 91 is realized by a CPU, a GPU, an MPU, a DSP, various other arithmetic devices, or a combination of these. The memory 93 is realized by a ROM, a RAM, a flash memory, or a combination of these.
In the following description, the control contents of the control device 90 will be described mainly with respect to the operation when defrosting the load side evaporator 35 and the operation when the pressure rises in the load side secondary refrigerant circuit 30. The control contents of the control device 90 will be described in detail later.

(Regarding defrosting of the load side evaporator 35)
When the load-side evaporator 35 is, for example, an air cooler, frost accumulates on the surface of the load-side evaporator 35, gradually decreasing the heat exchange efficiency. Therefore, it is necessary to perform defrosting periodically. In the secondary refrigerant refrigeration system 1 according to some embodiments, the condensation-side secondary refrigerant of the condensation-side secondary refrigerant circuit 50 is guided to the load-side evaporator 35 as follows, thereby defrosting the load-side evaporator 35. Hereinafter, the case of defrosting the first load-side evaporator 35A will be described as an example.

In the secondary refrigerant refrigeration system 1 according to some embodiments, when defrosting the first load evaporator 35A, first, the inlet shutoff valve 71 provided in the inlet refrigerant passage 37i connected to the inlet of the first load evaporator 35A is closed to evaporate the load secondary refrigerant liquid remaining in the first load evaporator 35A. Then, the outlet shutoff valve 72 provided in the outlet refrigerant passage 37o connected to the outlet of the first load evaporator 35A is closed.
Thereafter, the first on-off valve 73 is opened to guide the condensation side secondary refrigerant gas through the gas phase portion connecting passage 81 to the first load side evaporator 35A.

During normal operation of the load side secondary refrigerant circuit 30 and the condensing side secondary refrigerant circuit 50, the pressure of the gas phase section 52 in the condensing side secondary refrigerant circuit 50 is higher than the pressure of the gas phase section 32 in the load side secondary refrigerant circuit 30. Therefore, by opening the first on-off valve 73, the condensing side secondary refrigerant gas is supplied to the first load side evaporator 35A through the gas phase section connecting passage 81.
Then, by condensing the condensation side secondary refrigerant gas, which has a pressure higher than the pressure of the gas phase section 32 in the load side secondary refrigerant circuit 30, in the first load side evaporator 35A, defrosting can be performed using the condensation heat generated inside the first load side evaporator 35A.
As a result, the condensation side secondary refrigerant gas is condensed in the first load side evaporator 35A, and defrosting can be performed in a relatively short time by condensation heat transfer with a relatively high heat transfer coefficient. In addition, since the condensation side secondary refrigerant gas at a relatively high temperature (about 30°C) is supplied to the first load side evaporator 35A, the sensible heat of the condensation side secondary refrigerant gas can melt the frost, which contributes to shortening the time required for defrosting.
Furthermore, in some embodiments of the secondary refrigerant refrigeration system 1, defrosting is performed using the condensation side secondary refrigerant gas introduced into the first load side evaporator 35A, so that the entire first load side evaporator 35A can be heated relatively evenly from inside the first load side evaporator 35A and less unmelted material remains during defrosting, thereby shortening the time until defrosting is completed, i.e., the time required for defrosting.

At that time, the pressure of the gas phase section 52 in the condensation side secondary refrigerant circuit 50 decreases as the condensation side secondary refrigerant gas is supplied to the first load side evaporator 35A, thereby reducing the load on the condensation side condenser 55 and reducing the fan power of the cooling fan 57.
In this way, in the secondary refrigerant refrigeration system 1 according to some embodiments, the sensible heat for heating the first load side evaporator 35A and the heat of melting frost can be recovered in the form of a reduction in the fan power of the cooling fan 57.
When defrosting the second load side evaporator 35B or the third load side evaporator 35C, the valves may be operated in the same manner as when defrosting the first load side evaporator 35A described above.

As described above, the condensation side secondary refrigerant of the condensation side secondary refrigerant circuit 50 is introduced into the load side evaporator 35, whereby the condensation side secondary refrigerant and the load side secondary refrigerant are mixed, but this is not a problem because the components of the condensation side secondary refrigerant and the load side secondary refrigerant are the same.

Furthermore, when defrosting the load side evaporator 35, as described above, the inlet side refrigerant flow path 37i closes the inlet side shut-off valve 71, so that the refrigerant liquid condensed in the load side evaporator 35 accumulates in the load side evaporator 35, which may make it difficult to defrost the surface of the load side evaporator 35 in the area where the liquid has accumulated.
Therefore, it is preferable that the load side evaporator 35 is provided with a storage section capable of storing the refrigerant liquid condensed during defrosting.

When defrosting the load-side evaporator 35, the opening and closing operations of the valves may be performed manually or automatically.
When the above-mentioned valve opening and closing operations are performed automatically during the defrosting of the load-side evaporator 35, the control device 90 controls the opening and closing of each valve as follows. The following describes an example in which the first load-side evaporator 35A is defrosted.

For example, when a signal instructing the start of defrosting of the first load side evaporator 35A is input, the control device 90 outputs a control signal for closing the inlet side shut-off valve 71 provided in the inlet side refrigerant passage 37i connected to the inlet of the first load side evaporator 35A to the inlet side shut-off valve 71. This causes the inlet side shut-off valve 71 to close.
The signal to instruct the start of defrosting of the first load side evaporator 35A may be, for example, a signal input by an operator, i.e., a signal output when an operator performs an operation to instruct the start of defrosting. Alternatively, the signal to instruct the start of defrosting of the first load side evaporator 35A may be, for example, a signal automatically output after a certain period of normal operation.

Then, the control device 90 waits for the time required for the load-side secondary refrigerant liquid remaining in the first load-side evaporator 35A to evaporate, and then outputs a control signal to the outlet-side shut-off valve 72 provided in the outlet-side refrigerant flow path 37o connected to the outlet of the first load-side evaporator 35A to close the outlet-side shut-off valve 72. This closes the outlet-side shut-off valve 72.

Then, the control device 90 outputs a control signal to the first on-off valve 73 to open the first on-off valve 73. This causes the first on-off valve 73 to open, and the condensation side secondary refrigerant gas flows into the first load side evaporator 35A via the gas phase section connection flow path 81.

Whether or not defrosting is complete can be determined, for example, by confirming that the pressure inside the first load side evaporator 35A does not fall below the pressure corresponding to the freezing point, even when the supply of condensation side secondary refrigerant gas to the first load side evaporator 35A is stopped by closing the first on-off valve 73.
In this case, for example, the control device 90 outputs a control signal to the first opening/closing valve 73 to open the first opening/closing valve 73 as described above, and then outputs a control signal to close the first opening/closing valve 73 after a time period that is preset as the time required for defrost has elapsed.
If defrosting is not completed, the pressure in the first load side evaporator 35A gradually decreases to a pressure equal to or lower than the freezing point after the first on-off valve 73 is closed. If defrosting is completed, the pressure in the first load side evaporator 35A gradually decreases to a pressure equal to or lower than the freezing point after the first on-off valve 73 is closed, but does not become equal to or lower than the pressure equal to the freezing point.
In other words, after outputting a control signal to close the first opening/closing valve 73, if the pressure detection value in the first load side evaporator 35A detected by a pressure sensor not shown is below the pressure corresponding to the freezing point after a predetermined waiting time has elapsed, the control device 90 may determine that defrosting has not been completed, and if the detection value exceeds the pressure corresponding to the freezing point, it may determine that defrosting has been completed.

Also, a temperature sensor may be attached to a location on the surface of the first load side evaporator 35A that is least likely to be heated during defrosting, and the control device 90 may determine the end of defrosting based on the detected value of the temperature sensor. That is, the control device 90 outputs a control signal to open the first opening/closing valve 73 as described above, and then outputs a control signal to close the first opening/closing valve 73 after a time period that is preset as the time required for defrosting has elapsed.
If defrosting is not completed, the surface temperature of the first load side evaporator 35A gradually drops to below the freezing point after the first on-off valve 73 is closed. If defrosting is completed, the surface temperature of the first load side evaporator 35A does not drop to below the freezing point after the first on-off valve 73 is closed.
In other words, the control device 90 may determine that defrosting is completed after a predetermined waiting time has elapsed after outputting a control signal to close the first opening/closing valve 73 and when it determines that the surface temperature of the first load side evaporator 35A detected by the temperature sensor exceeds the freezing point.

In some embodiments of the secondary refrigerant refrigeration system 1, the load side evaporator 35 may be an air cooler for cooling air as described above. This allows the load side evaporator 35 to be used as an air cooler for cooling air, and makes it easier to defrost the air cooler.

In the secondary refrigerant refrigeration system 1 according to some embodiments, as described above, when defrosting the load side evaporator 35, the condensation side secondary refrigerant gas is guided to the load side evaporator 35 to adjust (increase) the pressure of the load side evaporator 35, thereby enabling defrosting to be performed uniformly and in a relatively short time over the entire surface of the load side evaporator 35. Therefore, in the secondary refrigerant refrigeration system 1 according to some embodiments, an electric heater or the like is not required for defrosting.

In some embodiments of the method for adjusting the pressure of the secondary refrigerant in the secondary refrigerant refrigeration system 1, the pressure of the load side evaporator 35 is adjusted by supplying the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection flow path 81. This allows the pressure of the load side evaporator 35 to be adjusted.

(When the pressure in the load side secondary refrigerant circuit 30 rises)
When the pressure in the load-side secondary refrigerant circuit 30 excessively increases due to an unintended increase in cooling load, it is necessary to reduce the pressure in the load-side secondary refrigerant circuit 30. In a conventional secondary refrigerant circuit, the pressure in the secondary refrigerant circuit is maintained by releasing the secondary refrigerant to the atmosphere from a safety valve provided in the secondary refrigerant circuit. However, when the unintended increase in cooling load is subsequently eliminated, the amount of secondary refrigerant in the secondary refrigerant circuit may be insufficient during normal operation of the load-side secondary refrigerant circuit 30.
In some embodiments of the secondary refrigerant refrigeration system 1, the pressure of the load side secondary refrigerant circuit 30 is maintained by releasing the load side secondary refrigerant gas in the load side secondary refrigerant circuit 30 to the condensation side secondary refrigerant circuit 50 as follows.

In the secondary refrigerant refrigeration system 1 according to some embodiments, when the control device 90 determines that the pressure of the load side secondary refrigerant detected by the pressure sensor 62 exceeds a preset threshold, the control device 90 outputs a control signal to the second on-off valve 74 to open the second on-off valve 74. This opens the second on-off valve 74, and the load side secondary refrigerant gas flows into the condensation side secondary refrigerant circuit 50 via the gas phase section connection flow path 81. This allows the pressure of the load side secondary refrigerant circuit 30 to be reduced.
In the condensation side secondary refrigerant circuit 50, the load side secondary refrigerant gas from the load side secondary refrigerant circuit 30 is condensed in the condensation side condenser 55 by operating the cooling fan 57, thereby suppressing the pressure increase in the condensation side secondary refrigerant circuit 50.

In the secondary refrigerant refrigeration system 1 according to some embodiments, as described above, the pressure of the load side evaporator 35 can be adjusted (reduced) by releasing the load side secondary refrigerant gas to the condensation side secondary refrigerant circuit 50. In the secondary refrigerant refrigeration system 1 according to some embodiments, the load side secondary refrigerant gas is not released to the atmosphere. This reduces the amount of refrigerant in the load side secondary refrigerant, but as described below, the secondary refrigerant liquid can be transferred from the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30 to eliminate the shortage of secondary refrigerant in the load side secondary refrigerant circuit 30, so there is no need to newly add secondary refrigerant to the load side secondary refrigerant circuit 30.

As described above, the load side secondary refrigerant is introduced into the condensation side secondary refrigerant circuit 50, whereby the condensation side secondary refrigerant and the load side secondary refrigerant are mixed, but this is not a problem because the components of the condensation side secondary refrigerant and the load side secondary refrigerant are the same.

According to some embodiments of the secondary refrigerant refrigeration system 1, the pressure of the load side evaporator 35 can be adjusted by supplying the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81.

In addition, according to the secondary refrigerant refrigeration system 1 according to some embodiments, for example, when defrosting the load side evaporator 35, the pressure inside the load side evaporator 35 can be increased with a relatively small supply of condensation side secondary refrigerant by closing the inlet side shutoff valve 71 and the outlet side shutoff valve 72, so that defrosting can be performed efficiently.

In some embodiments of the secondary refrigerant refrigeration system 1, the connection position of the gas phase connection flow passage 81 in the load side secondary refrigerant circuit 30 is downstream of the inlet side shut-off valve 71 and upstream of the outlet side shut-off valve 72. As a result, when defrosting the load side evaporator 35, for example, by closing the inlet side shut-off valve 71 and the outlet side shut-off valve 72, the pressure inside the load side evaporator 35 can be increased with a relatively small supply of condensation side secondary refrigerant, allowing efficient defrosting.

The secondary refrigerant refrigeration system 1 according to some embodiments includes a first on-off valve 73 and a second on-off valve 74 as connection flow passage shutoff valves capable of closing the gas phase connection flow passage 81. As a result, when it is not necessary to supply the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection flow passage 81, the first on-off valve 73 and the second on-off valve 74 as connection flow passage shutoff valves can be closed to block the flow of secondary refrigerant between the load side secondary refrigerant circuit 30 and the condensation side secondary refrigerant circuit 50.

(Transfer of secondary refrigerant liquid from the load side secondary refrigerant circuit 30 to the condensation side secondary refrigerant circuit 50)
As described above, when defrosting is performed, the condensation side secondary refrigerant flows into the load side secondary refrigerant circuit 30, so the secondary refrigerant in the condensation side secondary refrigerant circuit 50 decreases and the secondary refrigerant in the load side secondary refrigerant circuit 30 increases. Therefore, it is necessary to return the secondary refrigerant in the load side secondary refrigerant circuit 30 to the condensation side secondary refrigerant circuit 50.

During normal operation of the load side secondary refrigerant circuit 30 and the condensation side secondary refrigerant circuit 50, the pressure in the condensation side secondary refrigerant circuit 50 is higher than the pressure in the load side secondary refrigerant circuit 30. Therefore, in order to return the secondary refrigerant in the load side secondary refrigerant circuit 30 to the condensation side secondary refrigerant circuit 50, for example, a liquid return pump 84 must be used.

In the secondary refrigerant refrigeration system 1 according to some embodiments, when the control device 90 determines that the liquid level of the secondary refrigerant in the load side secondary refrigerant tank 31 detected by the level sensor 61 has exceeded a preset threshold, or when the control device 90 determines that the liquid level of the secondary refrigerant in the condensation side secondary refrigerant tank 51 detected by the level sensor 63 has fallen below a preset threshold, the control device 90 outputs a drive signal for the liquid return pump 84 to the liquid return pump 84 and outputs a control signal for opening the first pump valve 75 and the second pump valve 79 to the first pump valve 75 and the second pump valve 79. As a result, the liquid return pump 84 starts operating, and the first pump valve 75 and the second pump valve 79 are opened. Thus, the load side secondary refrigerant liquid in the load side secondary refrigerant tank 31 flows into the condensation side secondary refrigerant tank 51 through the first liquid phase connection flow path 83A. Thus, the shortage of secondary refrigerant in the condensation side secondary refrigerant circuit 50 is resolved.

The operation of the liquid return pump 84 and the operation of the first pump valve 75 and the second pump valve 79 may be performed automatically as described above, or may be performed manually.

(Transfer of secondary refrigerant liquid from the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30)
As described above, when the load side secondary refrigerant is released to the condensation side secondary refrigerant circuit 50 when the pressure of the load side secondary refrigerant circuit 30 rises, the load side secondary refrigerant flows into the condensation side secondary refrigerant circuit 50, so the secondary refrigerant in the load side secondary refrigerant circuit 30 decreases and the secondary refrigerant in the condensation side secondary refrigerant circuit 50 increases. Therefore, it is necessary to return the secondary refrigerant in the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30.

In the secondary refrigerant refrigeration system 1 according to some embodiments, when the control device 90 determines that the liquid level of the secondary refrigerant in the condensation side secondary refrigerant tank 51 detected by the level sensor 63 has exceeded a preset threshold, or when the control device 90 determines that the liquid level of the secondary refrigerant in the load side secondary refrigerant tank 31 detected by the level sensor 61 has fallen below a preset threshold, the control device 90 outputs a control signal to the liquid return valve 76 to open the liquid return valve 76. This causes the liquid return valve 76 to be opened.
As described above, during normal operation of the load side secondary refrigerant circuit 30 and the condensation side secondary refrigerant circuit 50, the pressure in the condensation side secondary refrigerant circuit 50 is higher than the pressure in the load side secondary refrigerant circuit 30. Therefore, when the liquid return valve 76 opens, the condensation side secondary refrigerant liquid in the condensation side secondary refrigerant tank 51 flows into the load side secondary refrigerant tank 31 via the second liquid phase section connecting passage 83B. Therefore, the shortage of secondary refrigerant in the load side secondary refrigerant circuit 30 is resolved.

The liquid return valve 76 may be operated automatically as described above, or may be operated manually.

In addition, if it is necessary to transfer secondary refrigerant liquid from the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30 when the pressure in the condensation side secondary refrigerant circuit 50 is lower than the pressure in the load side secondary refrigerant circuit 30 for some reason, the secondary refrigerant liquid may be transferred from the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30 using a liquid return pump 84 as follows.

In the secondary refrigerant refrigeration system 1 according to some embodiments, when the control device 90 determines that the liquid level of the secondary refrigerant in the condensation side secondary refrigerant tank 51 detected by the level sensor 63 has exceeded a preset threshold, or when the control device 90 determines that the liquid level of the secondary refrigerant in the load side secondary refrigerant tank 31 detected by the level sensor 61 has fallen below a preset threshold, the control device 90 outputs a drive signal for the liquid return pump 84 to the liquid return pump 84 and outputs a control signal for opening the connection valve 77 and the third pump valve 78 to the connection valve 77 and the third pump valve 78. As a result, the liquid return pump 84 starts operating, and the connection valve 77 and the third pump valve 78 are opened. As a result, the load side secondary refrigerant liquid in the condensation side secondary refrigerant tank 51 flows into the load side secondary refrigerant tank 31 via the second liquid phase connection flow path 83B, the connection flow path 85, the liquid return pump 84, and the discharge flow path 86.

The operation of the liquid return pump 84 and the connection valve 77 and third pump valve 78 may be performed automatically as described above, or may be performed manually.

In the secondary refrigerant refrigeration system 1 shown in FIG. 1, instead of providing the connection flow path 85 and the discharge flow path 86, a pump may be provided in the second liquid phase section connection flow path 83B, and the secondary refrigerant in the condensation side secondary refrigerant tank 51 may be pumped to the load side secondary refrigerant circuit 30 by this pump.

(Transport of secondary refrigerant liquid using an intermediate refrigerant tank)
As described above, after performing defrosting, it is necessary to return the secondary refrigerant in the load side secondary refrigerant circuit 30 to the condensing side secondary refrigerant circuit 50. During normal operation of the load side secondary refrigerant circuit 30 and the condensing side secondary refrigerant circuit 50, the pressure in the condensing side secondary refrigerant circuit 50 is higher than the pressure in the load side secondary refrigerant circuit 30. Therefore, in the above embodiment, the liquid return pump 84 is used to return the secondary refrigerant liquid to the condensing side secondary refrigerant circuit 50.
In the embodiment described below, the secondary refrigerant in the load side secondary refrigerant circuit 30 can be returned to the condensation side secondary refrigerant circuit 50 without using the liquid return pump 84 .

2 is a diagram for explaining the transfer of secondary refrigerant liquid using an intermediate refrigerant tank. In the secondary refrigerant refrigeration system 1 according to some embodiments, only a configuration required for transferring secondary refrigerant liquid from the load side secondary refrigerant tank 31 to the condensation side secondary refrigerant tank 51 using the intermediate refrigerant tank 41 is shown in FIG.
In the embodiment shown in Fig. 2, the secondary refrigerant refrigeration system 1 includes an intermediate refrigerant tank 41. In the embodiment shown in Fig. 2, the height position of the load side secondary refrigerant tank 31 is set to be higher than the height position of the intermediate refrigerant tank 41, and the height position of the condensation side secondary refrigerant tank 51 is set to be lower than the height position of the intermediate refrigerant tank 41.

In the embodiment shown in FIG. 2, the secondary refrigerant refrigeration system 1 includes a first gas-phase connection flow path 42 that connects the gas phase portion of the load side secondary refrigerant tank 31 and the gas phase portion of the intermediate refrigerant tank 41, a first gas-phase opening/closing valve 46 provided in the first gas-phase connection flow path 42, a first liquid-phase connection flow path 43 that connects the liquid phase portion of the load side secondary refrigerant tank 31 and the liquid phase portion of the intermediate refrigerant tank 41, and a first liquid-phase opening/closing valve 47 provided in the first liquid-phase connection flow path 43.

In the embodiment shown in FIG. 2, the secondary refrigerant refrigeration system 1 is provided with a gas-phase second connection flow path 44 that connects the gas phase portion of the condensation side secondary refrigerant tank 51 and the gas phase portion of the intermediate refrigerant tank 41, a gas-phase second opening/closing valve 48 provided in the gas-phase second connection flow path 44, a liquid-phase second connection flow path 45 that connects the liquid phase portion of the condensation side secondary refrigerant tank 51 and the liquid phase portion of the intermediate refrigerant tank 41, and a liquid-phase second opening/closing valve 49 provided in the liquid-phase second connection flow path 45.

During normal operation of the secondary refrigerant refrigeration system 1 shown in FIG. 2, the first gas phase on-off valve 46, the first liquid phase on-off valve 47, the second gas phase on-off valve 48, and the second liquid phase on-off valve 49 are closed.

In the secondary refrigerant refrigeration system 1 shown in FIG. 2, when the control device 90 determines that the liquid level of the secondary refrigerant in the condensation side secondary refrigerant tank 51 detected by the level sensor 63 has fallen below a preset threshold, or when the control device 90 determines that the liquid level of the secondary refrigerant in the load side secondary refrigerant tank 31 detected by the level sensor 61 has exceeded a preset threshold, the control device 90 outputs a control signal to the gas phase side first opening and closing valve 46 to open the gas phase side first opening and closing valve 46. As a result, the gas phase side first opening and closing valve 46 is opened, and the secondary refrigerant gas flows through the gas phase side first connection flow path 42, so that the pressures of the gas phase portion of the load side secondary refrigerant tank 31 and the gas phase portion of the intermediate refrigerant tank 41 become equal.

The control device 90 waits for a preset time required for the pressures in the gas phase portion of the load side secondary refrigerant tank 31 and the gas phase portion of the intermediate refrigerant tank 41 to become equal, and then outputs a control signal to the liquid phase first on-off valve 47 to open the liquid phase first on-off valve 47. This opens the liquid phase first on-off valve 47, and the secondary refrigerant liquid in the load side secondary refrigerant tank 31 flows into the intermediate refrigerant tank 41 via the liquid phase first connection flow path 43 due to the head difference of the secondary refrigerant liquid between the load side secondary refrigerant tank 31 and the intermediate refrigerant tank 41.

When the control device 90 determines that the liquid level of the secondary refrigerant in the load side secondary refrigerant tank 31 detected by the level sensor 61 has fallen below a preset threshold value for the transfer of secondary refrigerant liquid, it outputs a control signal to the gas phase first opening/closing valve 46 and the liquid phase first opening/closing valve 47 to close the gas phase first opening/closing valve 46 and the liquid phase first opening/closing valve 47. This causes the gas phase first opening/closing valve 46 and the liquid phase first opening/closing valve 47 to be closed.

The control device 90 then outputs a control signal to the gas phase second on-off valve 48 to open the gas phase second on-off valve 48. This causes the gas phase second on-off valve 48 to open, and the secondary refrigerant gas flows through the gas phase second connection flow path 44, so that the pressures of the gas phase portion of the condensation side secondary refrigerant tank 51 and the gas phase portion of the intermediate refrigerant tank 41 become equal.

The control device 90 waits for a preset time required for the pressures of the gas phase portion of the condensation side secondary refrigerant tank 51 and the gas phase portion of the intermediate refrigerant tank 41 to become equal, and then outputs a control signal to the liquid phase side second on-off valve 49 to open the liquid phase side second on-off valve 49. This opens the liquid phase side second on-off valve 49, and the secondary refrigerant liquid in the intermediate refrigerant tank 41 flows into the condensation side secondary refrigerant tank 51 via the liquid phase side second connection flow path 45 due to the head difference of the secondary refrigerant liquid between the intermediate refrigerant tank 41 and the condensation side secondary refrigerant tank 51.

When the control device 90 determines that the liquid level of the secondary refrigerant in the condensation side secondary refrigerant tank 51 detected by the level sensor 63 has exceeded a preset threshold value for the transfer of the secondary refrigerant liquid, it outputs a control signal to the gas phase side second on-off valve 48 and the liquid phase side second on-off valve 49 to close the gas phase side second on-off valve 48 and the liquid phase side second on-off valve 49. This closes the gas phase side second on-off valve 48 and the liquid phase side second on-off valve 49, completing the transfer of the secondary refrigerant liquid using the intermediate refrigerant tank 41.

The operation of the first gas phase side on-off valve 46, the first liquid phase side on-off valve 47, the second gas phase side on-off valve 48, and the second liquid phase side on-off valve 49 may be performed automatically as described above, or may be performed manually.

In addition, even if it is necessary to transfer the secondary refrigerant liquid from the condensation side secondary refrigerant circuit 50 to the load side secondary refrigerant circuit 30 when the pressure in the condensation side secondary refrigerant circuit 50 is lower than the pressure in the load side secondary refrigerant circuit 30 for some reason, the secondary refrigerant liquid can be transferred using the intermediate refrigerant tank 41. However, in this case, the height position of the load side secondary refrigerant tank 31 must be set to be lower than the height position of the intermediate refrigerant tank 41, and the height position of the condensation side secondary refrigerant tank 51 must be set to be higher than the height position of the intermediate refrigerant tank 41. Therefore, it is preferable to appropriately select the height position relationship between the load side secondary refrigerant tank 31, the intermediate refrigerant tank 41, and the condensation side secondary refrigerant tank 51 in the facility to which this system is applied.

The secondary refrigerant refrigeration system 1 shown in FIG. 1 includes a liquid phase section connecting flow passage 83 that connects the liquid phase section 34 of the load side secondary refrigerant circuit 30 and the liquid phase section 54 of the condensation side secondary refrigerant circuit 50 .
The secondary refrigerant refrigeration system 1 shown in Figure 2 further includes, as the liquid phase section connecting flow path 83, a first liquid phase side connecting flow path 43 and a second liquid phase side connecting flow path 45 instead of the first liquid phase section connecting flow path 83A.
This allows the secondary refrigerant from either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to be supplied to the other secondary refrigerant circuit via the gas phase section connection flow path 81, and then the supplied secondary refrigerant can be returned in the form of refrigerant liquid from the other secondary refrigerant circuit to either one of the secondary refrigerant circuits.

In the secondary refrigerant refrigeration system 1 shown in FIG. 2, the height positions of the load side secondary refrigerant tank 31, the intermediate refrigerant tank 41, and the condensation side secondary refrigerant tank 51 are set as described above, so that refrigerant liquid can be returned from the load side secondary refrigerant tank 31 to the condensation side secondary refrigerant tank 51 via the intermediate refrigerant tank 41 without using a pump.

The present disclosure is not limited to the above-described embodiments, but also includes variations of the above-described embodiments and appropriate combinations of these embodiments.

The contents described in each of the above embodiments can be understood, for example, as follows.
(1) The secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure includes a primary refrigerant circuit 10 in which a primary refrigerant circulates and in which a primary refrigerant compressor 11, a primary refrigerant condenser 13, and a primary refrigerant evaporator 17 are arranged. The secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure includes a load side secondary refrigerant circuit 30 including a load side evaporator 35 and circulating the load side secondary refrigerant to the load side evaporator 35 and the primary refrigerant evaporator 17. The secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure includes a condensation side condenser 55 and a condensation side secondary refrigerant circuit 50 including a condensation side condenser 55 and circulating the condensation side secondary refrigerant, which is the same refrigerant as the load side secondary refrigerant, to the condensation side condenser 55 and the primary refrigerant condenser 13. The secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure includes a gas phase portion connection flow path 81 that connects the gas phase portion 32 of the load side secondary refrigerant circuit 30 and the gas phase portion 52 of the condensation side secondary refrigerant circuit 50.

According to the above configuration (1), the pressure of the load side evaporator 35 can be adjusted by supplying the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase section connection flow path 81.

(2) In some embodiments, the configuration of (1) above may include an inlet-side shutoff valve 71 capable of closing the inlet-side refrigerant flow path 37i connected to the inlet of the load-side evaporator 35, and an outlet-side shutoff valve 72 capable of closing the outlet-side refrigerant flow path 37o connected to the outlet of the load-side evaporator 35.

According to the above configuration (2), for example, when defrosting the load side evaporator 35, the inlet side shutoff valve 71 and the outlet side shutoff valve 72 can be closed to increase the pressure inside the load side evaporator 35 with a relatively small supply of condensation side secondary refrigerant, so that defrosting can be performed efficiently.

(3) In some embodiments, in the configuration of (2) above, the connection position of the gas phase connection passage 81 in the load side secondary refrigerant circuit 30 may be downstream of the inlet side shutoff valve 71 and upstream of the outlet side shutoff valve 72.

According to the above configuration (3), for example, when defrosting the load side evaporator 35, the inlet side shutoff valve 71 and the outlet side shutoff valve 72 can be closed to increase the pressure inside the load side evaporator 35 with a relatively small supply of condensation side secondary refrigerant, so that defrosting can be performed efficiently.

(4) In some embodiments, in any of the configurations (1) to (3) above, it is preferable to provide a connection flow passage shutoff valve (first opening/closing valve 73, second opening/closing valve 74) that can close the gas phase section connection flow passage 81.

According to the above configuration (4), when it is not necessary to supply the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase section connection flow path 81, the connection flow path shutoff valves (first opening/closing valve 73, second opening/closing valve 74) can be closed to block the flow of secondary refrigerant between the load side secondary refrigerant circuit 30 and the condensation side secondary refrigerant circuit 50.

(5) In some embodiments, in any of the configurations (1) to (4) above, a liquid phase section connection flow path 83 may be provided that connects the liquid phase section 34 of the load side secondary refrigerant circuit 30 and the liquid phase section 54 of the condensation side secondary refrigerant circuit 50.

According to the above configuration (5), the secondary refrigerant from either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 can be supplied to the other secondary refrigerant circuit via the gas phase section connection flow path 81, and then the supplied secondary refrigerant can be returned in the form of refrigerant liquid from the other secondary refrigerant circuit to either one of the secondary refrigerant circuits.

(6) In some embodiments, the configuration of (5) above may further include a load side secondary refrigerant tank 31 provided in the load side secondary refrigerant circuit 30, a condensation side secondary refrigerant tank 51 provided in the condensation side secondary refrigerant circuit 50, and an intermediate refrigerant tank 41 provided in the middle of the liquid phase section connection flow path (liquid phase side first connection flow path 43, liquid phase side second connection flow path 45). The height position of the load side secondary refrigerant tank 31 may be higher than the height position of the intermediate refrigerant tank 41, and the height position of the condensation side secondary refrigerant tank 51 may be lower than the height position of the intermediate refrigerant tank 41.

According to the configuration (6) above, the refrigerant liquid can be returned from the load side secondary refrigerant tank 31 to the condensation side secondary refrigerant tank 51 via the intermediate refrigerant tank 41 without using a pump.

(7) In some embodiments, in any of the configurations (1) to (6) above, the load-side evaporator 35 may be an air cooler for cooling air.

According to the above configuration (7), the load-side evaporator 35 can be used as an air cooler for cooling air. Also, according to the above configuration (7), it becomes easier to defrost the air cooler.

(8) A method for adjusting the pressure of a secondary refrigerant according to at least one embodiment of the present disclosure is a method for adjusting the pressure of a secondary refrigerant in a secondary refrigerant refrigeration system 1. The secondary refrigerant refrigeration system 1 includes a primary refrigerant circuit 10 in which a primary refrigerant circulates and in which a primary refrigerant compressor 11, a primary refrigerant condenser 13, and a primary refrigerant evaporator 17 are arranged. The secondary refrigerant refrigeration system 1 includes a load side evaporator 35 and a load side secondary refrigerant circuit 30 that circulates the load side secondary refrigerant to the load side evaporator 35 and the primary refrigerant evaporator 17. The secondary refrigerant refrigeration system 1 includes a condensation side condenser 55 and a condensation side secondary refrigerant circuit 50 that circulates the condensation side secondary refrigerant, which is the same refrigerant as the load side secondary refrigerant, to the condensation side condenser 55 and the primary refrigerant condenser 13. The secondary refrigerant refrigeration system 1 includes a gas phase section connection flow path 81 that connects the gas phase section 32 of the load side secondary refrigerant circuit 30 and the gas phase section 52 of the condensation side secondary refrigerant circuit 50. In at least one embodiment of the method for adjusting the pressure of the secondary refrigerant according to the present disclosure, the pressure of the load side evaporator 35 is adjusted by supplying the secondary refrigerant of either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection flow path 81.

According to the above method (8), the pressure of the load side evaporator 35 can be adjusted by supplying the secondary refrigerant from either the load side secondary refrigerant circuit 30 or the condensation side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase section connection flow path 81.

1 Secondary refrigerant refrigeration system 10 Primary refrigerant circuit 11 Primary refrigerant compressor 13 Primary refrigerant condenser 17 Primary refrigerant evaporator 30 Load side secondary refrigerant circuit 31 Load side secondary refrigerant tank 32, 33 Gas phase section 34 Liquid phase section 35 Load side evaporator 41 Intermediate refrigerant tank 50 Condensation side secondary refrigerant circuit 51 Condensation side secondary refrigerant tank 52 Gas phase section 54 Liquid phase section 55 Condensation side condenser 71 Inlet side shutoff valve 72 Outlet side shutoff valve 81 Gas phase section connection flow path 83 Liquid phase section connection flow path

Claims (8)

a primary refrigerant circuit in which a primary refrigerant circulates and in which a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator are disposed;
A load side secondary refrigerant circuit including a load side evaporator and circulating a load side secondary refrigerant through the load side evaporator and the primary refrigerant evaporator;
a condensation-side secondary refrigerant circuit including a condensation-side condenser and circulating a condensation-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, through the condensation-side condenser and the primary refrigerant condenser;
A gas phase portion connecting flow path connecting a gas phase portion of the load side secondary refrigerant circuit and a gas phase portion of the condensation side secondary refrigerant circuit;
A secondary refrigerant refrigeration system comprising: an inlet side shutoff valve capable of closing an inlet side refrigerant flow passage connected to an inlet of the load side evaporator;
an outlet side shutoff valve capable of closing an outlet side refrigerant flow path connected to the outlet of the load side evaporator;
Equipped with
10. The secondary refrigerant refrigeration system of claim 1. A connection position of the gas phase portion connection flow path in the load side secondary refrigerant circuit is downstream of the inlet side shut-off valve and upstream of the outlet side shut-off valve.
3. The secondary refrigerant refrigeration system of claim 2. a connection flow passage closing valve capable of closing the gas phase portion connection flow passage;
Equipped with
A secondary refrigerant refrigeration system according to any one of claims 1 to 3. a liquid phase portion connecting flow path connecting a liquid phase portion of the load side secondary refrigerant circuit and a liquid phase portion of the condensation side secondary refrigerant circuit;
Equipped with
A secondary refrigerant refrigeration system according to any one of claims 1 to 3. A load side secondary refrigerant tank provided in the load side secondary refrigerant circuit;
a condensation side secondary refrigerant tank provided in the condensation side secondary refrigerant circuit;
an intermediate refrigerant tank provided in the middle of the liquid phase portion connecting flow path;
Equipped with
The height position of the load side secondary refrigerant tank is higher than the height position of the intermediate refrigerant tank,
The height position of the condensation side secondary refrigerant tank is lower than the height position of the intermediate refrigerant tank.
6. The secondary refrigerant refrigeration system of claim 5. The load side evaporator is an air cooler for cooling air.
A secondary refrigerant refrigeration system according to any one of claims 1 to 3. A method for adjusting pressure of a secondary refrigerant in a secondary refrigerant refrigeration system, comprising:
The secondary refrigerant refrigeration system comprises:
a primary refrigerant circuit in which a primary refrigerant circulates and in which a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator are disposed;
A load side secondary refrigerant circuit including a load side evaporator and circulating a load side secondary refrigerant through the load side evaporator and the primary refrigerant evaporator;
a condensation-side secondary refrigerant circuit including a condensation-side condenser and circulating a condensation-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, through the condensation-side condenser and the primary refrigerant condenser;
A gas phase portion connecting flow path connecting a gas phase portion of the load side secondary refrigerant circuit and a gas phase portion of the condensation side secondary refrigerant circuit;
Equipped with
The pressure of the load side evaporator is adjusted by supplying the secondary refrigerant of either the load side secondary refrigerant circuit or the condensation side secondary refrigerant circuit to the other secondary refrigerant circuit via the gas phase section connection flow path.
How to regulate the pressure of the secondary refrigerant.

Images