Secondary refrigerant refrigeration system and method for adjusting the pressure of the secondary refrigerant

Abstract

To adjust pressure of a load-side evaporator in a load-side secondary refrigerant circuit.SOLUTION: A secondary refrigerant refrigerator system according to at least one embodiment of the present disclosure comprises: a primary refrigerant circuit through which a primary refrigerant is circulated, and in which a primary refrigerant compressor, a primary refrigerant condenser and a primary refrigerant evaporator are arranged; a load-side secondary refrigerant circuit which includes a load-side evaporator, and circulates a load-side secondary refrigerant through the load-side evaporator and the primary refrigerant evaporator; a condensation-side secondary refrigerant circuit which includes a condensation-side condenser, and circulates a condensation-side secondary refrigerant identical to the load-side secondary refrigerant through the condensation-side condenser and the primary refrigerant condenser; and a gas phase part connection channel which connects a gas phase part of the load-side secondary refrigerant circuit and a gas phase part of the condensation-side secondary refrigerant circuit together.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a secondary refrigerant refrigeration system and a secondary refrigerant pressure adjustment method.

BACKGROUND ART

[0002] A secondary refrigerant refrigeration system is known that includes a primary refrigerant circuit in which a primary refrigerant circulates including an evaporator, and a secondary refrigerant circuit for supplying a secondary refrigerant cooled by the primary refrigerant in the evaporator to a cooling load (see, for example, Patent Document 1).

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] For example, in an evaporator that mainly uses the latent heat of the secondary refrigerant for cooling, such as the secondary refrigerant refrigeration system described in Patent Document 1, it is desired to control the pressure of the secondary refrigerant. For example, in order to perform defrosting in the evaporator, it is conceivable to increase the pressure of the secondary refrigerant in the evaporator to condense the secondary refrigerant in the evaporator at a temperature of 0°C or higher. Further, when the pressure of the secondary refrigerant in the evaporator rises due to an unintended increase in cooling load or the like, it is required to lower the pressure of the secondary refrigerant in the evaporator.

[0005] 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.

MEANS FOR SOLVING THE PROBLEMS

[0006] (1) A secondary refrigerant refrigeration system according to at least one embodiment of the present disclosure comprises: A primary refrigerant circuit in which a primary refrigerant circulates and which includes a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator, A load-side secondary refrigerant circuit including a load-side evaporator, which circulates load-side secondary refrigerant to the load-side evaporator and the primary refrigerant evaporator, A condensing-side secondary refrigerant circuit includes a condensing-side condenser, and circulates a condensing-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, to the condensing-side condenser and the primary refrigerant condenser, A gas phase connecting passage that connects the gas phase portion of the load-side secondary refrigerant circuit and the gas phase portion of the condensing-side secondary refrigerant circuit, It is equipped with.

[0007] (2) 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, The aforementioned secondary refrigerant refrigeration system is A primary refrigerant circuit in which a primary refrigerant circulates and which includes a primary refrigerant compressor, a primary refrigerant condenser, and a primary refrigerant evaporator, A load-side secondary refrigerant circuit including a load-side evaporator, which circulates load-side secondary refrigerant to the load-side evaporator and the primary refrigerant evaporator, A condensing-side secondary refrigerant circuit includes a condensing-side condenser, and circulates a condensing-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, to the condensing-side condenser and the primary refrigerant condenser, A gas phase connecting passage that connects the gas phase portion of the load-side secondary refrigerant circuit and the gas phase portion of the condensing-side secondary refrigerant circuit, Equipped with, The pressure of the load-side evaporator is adjusted by supplying the secondary refrigerant from either the load-side secondary refrigerant circuit or the condensing-side secondary refrigerant circuit to the other secondary refrigerant circuit via the gas phase connection passage. [Effects of the Invention]

[0008] 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. [Brief explanation of the drawing]

[0009] [Figure 1] This is a diagram of a secondary refrigerant refrigeration system according to several embodiments. [Figure 2] This diagram illustrates the transfer of secondary refrigerant liquid using an intermediate refrigerant tank. [Modes for carrying out the invention]

[0010] Hereinafter, several embodiments of this disclosure will be described with reference to the attached drawings. However, the dimensions, materials, shapes, relative arrangements, etc., of the components described or shown in the drawings as embodiments are not intended to limit the scope of this disclosure, but are merely illustrative examples. For example, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" should not only strictly describe such arrangements, but also describe states of relative displacement with tolerances or angles or distances that allow for the same function to be achieved. For example, expressions such as "identical," "equal," and "homogeneous" that describe things being in an equal state not only describe a state of being strictly equal, but also describe a state in which there is a tolerance or a difference that is sufficient to achieve the same function. For example, expressions describing shapes such as squares or cylinders shall not only represent geometrically precise shapes such as squares or cylinders, but also shapes that include protrusions, chamfers, etc., to the extent that the same effect can be achieved. On the other hand, expressions such as "to possess," "to be equipped with," "to have," "to include," or "to have" a single component are not exclusive expressions that exclude the existence of other components.

[0011] Figure 1 is a schematic diagram of a secondary refrigerant refrigeration system according to several embodiments. The secondary refrigerant refrigeration system 1 according to several embodiments comprises a primary refrigerant circuit 10, a load-side secondary refrigerant circuit 30, and a condensation-side secondary refrigerant circuit 50.

[0012] (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 constitutes a refrigeration cycle, in which a primary refrigerant compressor 11, a primary refrigerant condenser 13, an expansion valve 15, and a primary refrigerant evaporator 17 are arranged, and a 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 the 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 in the condensation-side secondary refrigerant circuit 50. The condensed primary refrigerant liquid is depressurized via the expansion valve 15 and sent to the primary refrigerant evaporator 17 that functions as the 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 in the load-side secondary refrigerant circuit 30 and vaporizes. The vaporized primary refrigerant is compressed again by the primary refrigerant compressor 11.

[0013] In the secondary refrigerant refrigeration system 1 according to some embodiments, a refrigerant of any composition can be used as the primary refrigerant. In the secondary refrigerant refrigeration system 1 according to some embodiments, the primary refrigerant circuit 10 is arranged, for example, inside the refrigerator 3.

[0014] (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, a load-side secondary refrigerant circulates, and latent heat 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 the evaporator of the load-side secondary refrigerant circuit 30. Note that 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 3, but it may be 2 or less, or 4 or more. For convenience of explanation, it is assumed that among the three load-side evaporators 35, one is the first load-side evaporator 35A, another is the second load-side evaporator 35B, and the remaining one is the third load-side evaporator 35C.

[0015] 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, exits the load-side evaporator 35 in a gas-liquid mixed state. In the secondary refrigerant refrigeration system 1 shown in FIG. 1, when the load-side evaporator 35 is, for example, a component for cooling air in a refrigerated warehouse, the load-side evaporator 35 is an air cooler. The load-side secondary refrigerant that has exited the load-side evaporator 35 in a gas-liquid mixed state is sent to the load-side secondary refrigerant tank 31. Inside the load-side secondary refrigerant tank 31, the load-side secondary refrigerant is separated into gas and liquid phases, and the gas-phase load-side secondary refrigerant is cooled by the primary refrigerant in the primary refrigerant circuit 10 in the primary refrigerant evaporator 17, 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. It should be noted that the load-side secondary refrigerant circuit 30 in the present invention includes a line that sends the load-side secondary refrigerant liquid from the load-side secondary refrigerant tank 31 to the load-side evaporator 35 via the refrigerant pump 33, and returns to the load-side secondary refrigerant tank 31 after a part of the refrigerant is vaporized to form a gas-liquid mixed state, and a line that cools the gas-phase load-side secondary refrigerant from the load-side secondary refrigerant tank 31 with the primary refrigerant in the primary refrigerant circuit 10 to liquefy it, and then returns it to the load-side secondary refrigerant tank 31.

[0016] 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 height of the load-side secondary refrigerant inside the load-side secondary refrigerant tank 31. Further, 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 shutoff valves 71 and each of the outlet-side shutoff valves 72 is open.

[0017] In some embodiments of the load-side secondary refrigerant circuit 30, a pressure sensor 62 is provided for detecting the pressure of the load-side secondary refrigerant in the refrigerant flow path 38 downstream of each outlet-side shut-off valve 72 and upstream of the load-side secondary refrigerant tank 31.

[0018] (Condensing side secondary refrigerant circuit 50) In some embodiments of the secondary refrigerant refrigeration system 1, the condensing secondary refrigerant circuit 50 comprises a condensing secondary refrigerant tank 51, a refrigerant pump 53, and a condensing condenser 55. The condensing secondary refrigerant circulates in this circuit, and latent heat exchange takes place in the condensing condenser 55. In the condensing secondary refrigerant circuit 50, the condensing secondary refrigerant liquid from the condensing secondary refrigerant tank 51 is sent to the primary refrigerant condenser 13 by the refrigerant pump 53. In the primary refrigerant condenser 13, the condensing secondary refrigerant liquid absorbs heat from the primary refrigerant in the primary refrigerant circuit 10 and vaporizes. The vaporized condensing secondary refrigerant is sent to the condensing condenser 55. In the condensing condenser 55, the condensing secondary refrigerant is cooled by outside air blown by a cooling fan 57 and liquefies. The liquefied condensing secondary refrigerant returns to the condensing secondary refrigerant tank 51.

[0019] In some embodiments of the condensing secondary refrigerant circuit 50, the condensing secondary refrigerant tank 51 is provided with a level sensor 63 for detecting the liquid level of the condensing secondary refrigerant in the condensing secondary refrigerant tank 51.

[0020] 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; and for example, if the load-side secondary refrigerant is R134a, the condensation-side secondary refrigerant is R134a. In the following explanation, when there is no need to distinguish between the load-side secondary refrigerant and the condensation-side secondary refrigerant, they will simply be referred to as secondary refrigerants.

[0021] (Gas phase connection channel 81) In some embodiments of the secondary refrigerant refrigeration system 1, a gas phase connecting passage 81 is provided that connects the gas phase section 32 (hereinafter also simply referred to as "gas phase section 32") of the load-side secondary refrigerant circuit 30, which includes a gas-liquid mixed state, with the gas phase section 52 of the condensing-side secondary refrigerant circuit 50. The gas phase connecting passage 81 is connected to the load-side secondary refrigerant circuit 30, for example, to each load-side evaporator 35 via the first on-off 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. The gas phase connecting passage 81 is preferably connected to the load-side secondary refrigerant circuit 30 via the second on-off valve 74 to a refrigerant passage 38 located downstream of each outlet-side shut-off valve 72 and upstream of the load-side secondary refrigerant tank 31. However, it may also be connected to the gas phase section 39 of the load-side secondary refrigerant circuit 30, i.e., to the refrigerant passage 40 connecting the gas phase section of the load-side secondary refrigerant tank 31 and the primary refrigerant evaporator 17. The gas phase connection channel 81 is connected to a refrigerant channel 56 in relation to the condensing-side secondary refrigerant circuit 50, for example, downstream of the primary refrigerant condenser 13 and upstream of the condensing-side condenser 55. During normal operation of the load-side secondary refrigerant circuit 30, the first on-off valve 73 and the second on-off valve 74 are closed, respectively. The function of the gas phase connecting channel 81 will be described in detail later.

[0022] (Liquid phase connection channel 83) In some embodiments of the secondary refrigerant refrigeration system 1, a liquid phase connecting passage 83 is provided that connects the liquid phase portion 34 of the load-side secondary refrigerant circuit 30 and the liquid phase portion 54 of the condensing-side secondary refrigerant circuit 50. In the secondary refrigerant refrigeration system 1 shown in Figure 1, the liquid phase connection channel 83 includes, for example, a first liquid phase connection channel 83A and a second liquid phase connection channel 83B. The first liquid phase connecting channel 83A and the second liquid phase connecting channel 83B are connected to the load-side secondary refrigerant tank 31 with respect to the load-side secondary refrigerant circuit 30. Furthermore, the first liquid phase connecting channel 83A and the second liquid phase connecting channel 83B are connected to the condensing side secondary refrigerant tank 51 with respect to the condensing side secondary refrigerant circuit 50. The first liquid phase connecting passage 83A is provided with a liquid return pump 84 for supplying secondary refrigerant liquid from the load-side secondary refrigerant tank 31 to the condensing-side secondary refrigerant tank 51, a first pump valve 75, and a second pump valve 79. The first pump valve 75 is located on the discharge side of the liquid return pump 84, and the second pump valve 79 is located on the suction side of the liquid return pump 84. The second liquid phase connecting channel 83B is provided with a liquid return valve 76 for returning the secondary refrigerant liquid from the condensing-side secondary refrigerant tank 51 to the load-side secondary refrigerant tank 31.

[0023] Furthermore, the secondary refrigerant refrigeration system 1 shown in Figure 1 is provided with a connecting passage 85 that connects the first liquid phase connecting passage 83A and the second liquid phase connecting passage 83B, and a discharge passage 86 that connects the first liquid phase connecting passage 83A downstream of the liquid return pump 84 to the load-side secondary refrigerant tank 31. The connecting passage 85 connects the second liquid phase connecting passage 83B between the condensing secondary refrigerant tank 51 and the liquid return valve 76, and the first liquid phase connecting passage 83A between the second pump valve 79 and the liquid return pump 84. A connecting valve 77 is provided in the connecting passage 85.

[0024] The discharge passage 86 connects the first liquid phase connecting passage 83A between the liquid return pump 84 and the first pump valve 75 to the load-side secondary refrigerant tank 31. A third pump valve 78 is provided in the discharge passage 86.

[0025] 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 connecting valve 77, and the liquid return valve 76 are all closed, and the liquid return pump 84 is stopped.

[0026] In some embodiments, the secondary refrigerant refrigeration system 1 includes a control device 90 for controlling various parts of the secondary refrigerant refrigeration system 1. The control device 90 includes a processor 91 that performs various calculations and a memory 93 that stores various data processed by the processor 91 either temporarily or non-temporarily. The processor 91 is implemented by a CPU, GPU, MPU, DSP, various other calculation devices, or a combination thereof. The memory 93 is implemented by ROM, RAM, flash memory, or a combination thereof. The following explanation will describe the control functions of the control device 90, mainly focusing on its operation when defrosting the load-side evaporator 35 and its operation when the pressure rises in the load-side secondary refrigerant circuit 30. The control functions of the control device 90 will be described in more detail later.

[0027] (Regarding defrosting of the load-side evaporator 35) If the load-side evaporator 35 is, for example, an air cooler, frost will accumulate on the surface of the load-side evaporator 35, gradually reducing its heat exchange efficiency. Therefore, it is necessary to defrost it periodically. In some embodiments of the secondary refrigerant refrigeration system 1, defrosting of the load-side evaporator 35 can be performed by guiding the condensing-side secondary refrigerant from the condensing-side secondary refrigerant circuit 50 to the load-side evaporator 35 as follows. The following explanation will use the case of defrosting the first load-side evaporator 35A as an example.

[0028] In some embodiments of the secondary refrigerant refrigeration system 1, when defrosting the first load-side evaporator 35A, first, the inlet-side shut-off valve 71 provided in the inlet-side refrigerant flow path 37i connected to the inlet of the first load-side evaporator 35A is closed to evaporate the load-side secondary refrigerant liquid remaining in the first load-side evaporator 35A. Then, 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 is closed. Subsequently, the first on-off valve 73 is opened, and the condensing side secondary refrigerant gas is guided to the first load side evaporator 35A via the gas phase connection passage 81.

[0029] During normal operation of the load-side secondary refrigerant circuit 30 and the condensing-side secondary refrigerant circuit 50, the pressure in the gas phase section 52 within the condensing-side secondary refrigerant circuit 50 is higher than the pressure in the gas phase section 32 within 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 via the gas phase section connection passage 81. Furthermore, by condensing the condensing-side secondary refrigerant gas, which is at a pressure higher than the pressure in the gas phase section 32 within the load-side secondary refrigerant circuit 30, within the first load-side evaporator 35A, defrosting can be performed using the heat of condensation generated inside the first load-side evaporator 35A. As a result, the condensing secondary refrigerant gas in the first load-side evaporator 35A condenses, allowing defrosting to be performed in a relatively short time through condensation heat transfer, which has a relatively high heat transfer coefficient. In addition, since the condensing secondary refrigerant gas at a relatively high temperature (around 30°C) is supplied to the first load-side evaporator 35A, the sensible heat of the condensing secondary refrigerant gas can melt the frost, thus contributing to a reduction in the time required for defrosting. Furthermore, in some embodiments of the secondary refrigerant refrigeration system 1, defrosting is performed using condensed secondary refrigerant gas introduced into the first load-side evaporator 35A. This allows the entire first load-side evaporator 35A to be heated relatively uniformly from the inside, reducing the amount of undissolved refrigerant during defrosting, and thus shortening the time required for defrosting to complete.

[0030] At that time, the condensing-side secondary refrigerant gas is supplied to the first load-side evaporator 35A, which lowers the pressure in the gas phase section 52 within the condensing-side secondary refrigerant circuit 50. As a result, the load on the condensing-side condenser 55 decreases, and the fan power of the cooling fan 57 decreases. Thus, in the secondary refrigerant refrigeration system 1 according to several embodiments, the sensible heat for heating the first load-side evaporator 35A and the heat of frost fusion can be recovered in the form of a reduction in the fan power of the cooling fan 57. Furthermore, when defrosting the second load-side evaporator 35B or the third load-side evaporator 35C, the same valve operation as described above for defrosting the first load-side evaporator 35A should be performed.

[0031] As described above, the condensing secondary refrigerant in the condensing secondary refrigerant circuit 50 is guided to the load-side evaporator 35, which mixes the condensing secondary refrigerant and the load-side secondary refrigerant. However, since the components of the condensing secondary refrigerant and the load-side secondary refrigerant are the same, there is no problem.

[0032] 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. This can cause condensed refrigerant liquid to accumulate inside the load-side evaporator 35, potentially making 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 be provided with a storage section capable of storing the refrigerant liquid that has condensed during defrosting.

[0033] When defrosting the load-side evaporator 35 as described above, the opening and closing operation of the valve described above may be performed manually or automatically. When the opening and closing operations of the valves described above 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 explanation will use the case of defrosting the first load-side evaporator 35A as an example.

[0034] For example, when the control device 90 receives a signal instructing the start of defrosting of the first load-side evaporator 35A, it outputs a control signal to the inlet-side shut-off valve 71, which is located in the inlet-side refrigerant flow path 37i connected to the inlet of the first load-side evaporator 35A, to close the inlet-side shut-off valve 71. As a result, the inlet-side shut-off valve 71 closes. The signal instructing the start of defrosting of the first load-side evaporator 35A may be a signal input by, for example, an operator, i.e., a signal output when an operator performs an operation to instruct the start of defrosting. Alternatively, the signal instructing the start of defrosting of the first load-side evaporator 35A may be a signal that is automatically output after, for example, normal operation has been performed for a certain period of time.

[0035] Next, the control device 90 waits for the time necessary 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, which is 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. As a result, the outlet-side shut-off valve 72 closes.

[0036] Subsequently, the control device 90 outputs a control signal to the first on-off valve 73 to open it. As a result, the first on-off valve 73 opens, and the condensing side secondary refrigerant gas flows into the first load side evaporator 35A via the gas phase connection passage 81.

[0037] Furthermore, whether or not defrosting is complete can be determined, for example, by closing the first on-off valve 73 to stop the supply of condensing secondary refrigerant gas to the first load-side evaporator 35A, and confirming that the pressure inside the first load-side evaporator 35A does not fall below the pressure corresponding to the freezing point. In this case, for example, the control device 90 outputs a control signal to the first on-off valve 73 to open the first on-off valve 73 as described above, and then outputs a control signal to close the first on-off valve 73 after a predetermined time has elapsed, for example, as the time required for defrosting. If defrosting is not complete, after closing the first on-off valve 73, the pressure inside the first load-side evaporator 35A will gradually decrease to below the pressure corresponding to the freezing point. However, if defrosting is complete, even if the pressure inside the first load-side evaporator 35A gradually decreases after closing the first on-off valve 73, it will not fall below the pressure corresponding to the freezing point. In other words, the control device 90 may, after outputting a control signal to close the first on-off valve 73, and after a predetermined waiting time has elapsed, determine that defrosting is not complete if the pressure detected by a pressure sensor (not shown) in the first load-side evaporator 35A is below the pressure corresponding to the freezing point, and determine that defrosting is complete if the detected value exceeds the pressure corresponding to the freezing point.

[0038] Alternatively, a temperature sensor may be installed on the surface of the first load-side evaporator 35A at a location that is least likely to be heated during defrosting, and the control device 90 may determine the end of defrosting based on the value detected by this temperature sensor. That is, as described above, the control device 90 outputs a control signal to the first on-off valve 73 to open it, and then outputs a control signal to close the first on-off valve 73 after a predetermined time has elapsed, for example, as the time required for defrosting. If defrosting is not complete, after closing the first on-off valve 73, the surface temperature of the first load-side evaporator 35A will gradually decrease to below freezing point. Conversely, if defrosting is complete, after closing the first on-off valve 73, the surface temperature of the first load-side evaporator 35A will not fall below freezing point. In other words, the control device 90 may determine that defrosting is complete after outputting a control signal to close the first on-off valve 73, and after a predetermined waiting period has elapsed, and after determining that the surface temperature of the first load-side evaporator 35A detected by the temperature sensor has exceeded the freezing point.

[0039] 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 also facilitates defrosting of the air cooler.

[0040] In some embodiments of the secondary refrigerant refrigeration system 1, as described above, defrosting of the load-side evaporator 35 can be performed by introducing the condensed secondary refrigerant gas to the load-side evaporator 35 and adjusting (increasing) the pressure of the load-side evaporator 35. By introducing the condensed secondary refrigerant gas to the load-side evaporator 35, heating from inside the load-side evaporator 35 is possible, and defrosting can be performed uniformly and in a relatively short time across the entire surface of the load-side evaporator 35. Therefore, in some embodiments of the secondary refrigerant refrigeration system 1, electric heaters or the like for defrosting are unnecessary.

[0041] In a secondary refrigerant pressure adjustment method in a secondary refrigerant refrigeration system 1 according to several embodiments, the pressure of the load-side evaporator 35 is adjusted by supplying the secondary refrigerant from either the load-side secondary refrigerant circuit 30 or the condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81. This allows the pressure of the load-side evaporator 35 to be adjusted.

[0042] (When the pressure in the load-side secondary refrigerant circuit 30 rises) If the pressure in the load-side secondary refrigerant circuit 30 rises excessively due to an unintended increase in cooling load, it is necessary to reduce the pressure in the load-side secondary refrigerant circuit 30. In conventional secondary refrigerant circuits, the pressure in the secondary refrigerant circuit is maintained by releasing secondary refrigerant into the atmosphere through a safety valve provided in the secondary refrigerant circuit. However, if the unintended increase in cooling load is subsequently resolved, there is a risk that the amount of secondary refrigerant in the secondary refrigerant circuit will 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 in the load-side secondary refrigerant circuit 30 is maintained by releasing the load-side secondary refrigerant gas from the load-side secondary refrigerant circuit 30 into the condensing-side secondary refrigerant circuit 50 as follows.

[0043] In some embodiments of the secondary refrigerant refrigeration system 1, 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, it outputs a control signal to the second on-off valve 74 to open the second on-off valve 74. As a result, the second on-off valve 74 opens, and the load-side secondary refrigerant gas flows into the condensing-side secondary refrigerant circuit 50 via the gas phase connection passage 81. Therefore, the pressure in the load-side secondary refrigerant circuit 30 can be reduced. In the condensing secondary refrigerant circuit 50, the cooling fan 57 is operated to condense the load-side secondary refrigerant gas from the load-side secondary refrigerant circuit 30 in the condensing-side condenser 55, thereby suppressing the pressure rise in the condensing secondary refrigerant circuit 50.

[0044] In some embodiments of the secondary refrigerant refrigeration system 1, as described above, the pressure in the load-side evaporator 35 can be adjusted (reduced) by releasing the load-side secondary refrigerant gas into the condensing-side secondary refrigerant circuit 50. In some embodiments of the secondary refrigerant refrigeration system 1, the load-side secondary refrigerant gas is not released into the atmosphere. This reduces the amount of secondary refrigerant in the load-side secondary refrigerant circuit, but as described later, the shortage of secondary refrigerant in the load-side secondary refrigerant circuit 30 can be resolved by transferring the secondary refrigerant liquid from the condensing-side secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30, so there is no need to add any additional secondary refrigerant to the load-side secondary refrigerant circuit 30.

[0045] As described above, by introducing the load-side secondary refrigerant into the condensing-side secondary refrigerant circuit 50, the condensing-side secondary refrigerant and the load-side secondary refrigerant are mixed. However, since the components of the condensing-side secondary refrigerant and the load-side secondary refrigerant are the same, there is no problem.

[0046] According to several embodiments of the secondary refrigerant refrigeration system 1, 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 condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81.

[0047] Furthermore, according to some embodiments of the secondary refrigerant refrigeration system 1, 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 condensing-side secondary refrigerant by closing the inlet-side shut-off valve 71 and the outlet-side shut-off valve 72, thereby enabling efficient defrosting.

[0048] In some embodiments of the secondary refrigerant refrigeration system 1, the connection position of the gas phase connection 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. This allows for efficient defrosting, for example, when defrosting the load-side evaporator 35, by closing the inlet-side shut-off valve 71 and the outlet-side shut-off valve 72, the internal pressure of the load-side evaporator 35 can be increased with a relatively small supply of condensing-side secondary refrigerant.

[0049] In some embodiments of the secondary refrigerant refrigeration system 1, a first on-off valve 73 and a second on-off valve 74 are provided as connection channel shut-off valves that can close the gas phase connection channel 81. As a result, when it is not necessary to supply the secondary refrigerant from either the load-side secondary refrigerant circuit 30 or the condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection channel 81, the flow of secondary refrigerant between the load-side secondary refrigerant circuit 30 and the condensing-side secondary refrigerant circuit 50 can be blocked by closing the first on-off valve 73 and the second on-off valve 74, which are connection channel shut-off valves.

[0050] (Transfer of secondary refrigerant liquid from the load-side secondary refrigerant circuit 30 to the condensing-side secondary refrigerant circuit 50) As described above, when defrosting is performed, the condensing secondary refrigerant flows into the load-side secondary refrigerant circuit 30, so the amount of secondary refrigerant in the condensing secondary refrigerant circuit 50 decreases and the amount of secondary refrigerant in the load-side secondary refrigerant circuit 30 increases. Therefore, it is necessary to return the secondary refrigerant from the load-side secondary refrigerant circuit 30 to the condensing secondary refrigerant circuit 50.

[0051] 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 order to return the secondary refrigerant from the load-side secondary refrigerant circuit 30 to the condensing-side secondary refrigerant circuit 50, it is necessary to use, for example, a liquid return pump 84.

[0052] In some embodiments of the secondary refrigerant refrigeration system 1, the control device 90, for example, when it 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 it determines that the liquid level of the secondary refrigerant in the condensing-side secondary refrigerant tank 51 detected by the level sensor 63 has fallen below a preset threshold, outputs a drive signal for the liquid return pump 84 to the liquid return pump 84 and outputs control signals to the first pump valve 75 and the second pump valve 79 to open them. As a result, the liquid return pump 84 starts operating and the first pump valve 75 and the second pump valve 79 open. Therefore, the load-side secondary refrigerant liquid in the load-side secondary refrigerant tank 31 flows into the condensing-side secondary refrigerant tank 51 via the first liquid phase connection passage 83A. Thus, the shortage of secondary refrigerant in the condensing-side secondary refrigerant circuit 50 is resolved.

[0053] 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 manually.

[0054] (Transfer of secondary refrigerant liquid from the condensing-side secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30) As described above, when the load-side secondary refrigerant circuit 30 experiences a pressure increase and the load-side secondary refrigerant is released into the condensing-side secondary refrigerant circuit 50, the load-side secondary refrigerant flows into the condensing-side secondary refrigerant circuit 50. This reduces the amount of secondary refrigerant in the load-side secondary refrigerant circuit 30 and increases the amount of secondary refrigerant in the condensing-side secondary refrigerant circuit 50. Therefore, it is necessary to return the secondary refrigerant from the condensing-side secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30.

[0055] In some embodiments of the secondary refrigerant refrigeration system 1, the control device 90 determines, for example, that the liquid level of the secondary refrigerant in the condensing-side secondary refrigerant tank 51 detected by the level sensor 63 has exceeded a preset threshold, or 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, and outputs a control signal to the liquid return valve 76 to open the liquid return valve 76. As a result, the liquid return valve 76 is opened. As described above, 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, when the liquid return valve 76 opens, the condensing-side secondary refrigerant liquid in the condensing-side secondary refrigerant tank 51 flows into the load-side secondary refrigerant tank 31 via the second liquid phase connection passage 83B. Thus, the shortage of secondary refrigerant in the load-side secondary refrigerant circuit 30 is resolved.

[0056] The liquid return valve 76 may be operated automatically as described above, or it may be operated manually.

[0057] Furthermore, if, for any reason, the pressure in the condensing-side secondary refrigerant circuit 50 is lower than the pressure in the load-side secondary refrigerant circuit 30, and it is necessary to transfer the secondary refrigerant liquid from the condensing-side secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30, the secondary refrigerant liquid may be transferred from the condensing-side secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30 using the liquid return pump 84 as described below.

[0058] In some embodiments of the secondary refrigerant refrigeration system 1, the control device 90, for example, when it determines that the liquid level of the secondary refrigerant in the condensing-side secondary refrigerant tank 51 detected by the level sensor 63 has exceeded a preset threshold, or when it 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, outputs a drive signal for the liquid return pump 84 to the liquid return pump 84 and outputs control signals to the connecting valve 77 and the third pump valve 78 to open the connecting valve 77 and the third pump valve 78. As a result, the liquid return pump 84 starts operating and the connecting valve 77 and the third pump valve 78 open. As a result, the load-side secondary refrigerant liquid in the condensing-side secondary refrigerant tank 51 flows into the load-side secondary refrigerant tank 31 via the second liquid phase connecting passage 83B, the connecting passage 85, the liquid return pump 84, and the discharge passage 86.

[0059] The operation of the liquid return pump 84, the connection valve 77, and the third pump valve 78 may be performed automatically as described above, or manually.

[0060] In addition, in the secondary refrigerant refrigeration system 1 shown in Figure 1, instead of providing a connection channel 85 and a discharge channel 86, a pump may be provided in the second liquid phase connection channel 83B, and this pump may be used to pressurize the secondary refrigerant in the condensing-side secondary refrigerant tank 51 to the load-side secondary refrigerant circuit 30.

[0061] (Transfer of secondary refrigerant liquid using an intermediate refrigerant tank) As described above, after defrosting, it is necessary to return the secondary refrigerant from 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 embodiment described above, the liquid return pump 84 was used to return the secondary refrigerant liquid to the condensing-side secondary refrigerant circuit 50. In the embodiment described below, the secondary refrigerant from the load-side secondary refrigerant circuit 30 can be returned to the condensing-side secondary refrigerant circuit 50 without using the liquid return pump 84.

[0062] Figure 2 is a diagram illustrating the transfer of secondary refrigerant liquid using an intermediate refrigerant tank. In Figure 2, among several embodiments of the secondary refrigerant refrigeration system 1, only the configuration necessary for transferring secondary refrigerant liquid from the load-side secondary refrigerant tank 31 to the condensing-side secondary refrigerant tank 51 using an intermediate refrigerant tank 41 is shown. In the embodiment shown in Figure 2, the secondary refrigerant refrigeration system 1 includes an intermediate refrigerant tank 41. In the embodiment shown in Figure 2, the height of the load-side secondary refrigerant tank 31 is set to be higher than the height of the intermediate refrigerant tank 41, and the height of the condensing-side secondary refrigerant tank 51 is set to be lower than the height of the intermediate refrigerant tank 41.

[0063] In the embodiment shown in Figure 2, the secondary refrigerant refrigeration system 1 is provided with a first gas phase connecting passage 42 that connects the gas phase portion of the load-side secondary refrigerant tank 31 to the gas phase portion of the intermediate refrigerant tank 41, a first gas phase on-off valve 46 provided in the first gas phase connecting passage 42, a first liquid phase connecting passage 43 that connects the liquid phase portion of the load-side secondary refrigerant tank 31 to the liquid phase portion of the intermediate refrigerant tank 41, and a first liquid phase on-off valve 47 provided in the first liquid phase connecting passage 43.

[0064] In the embodiment shown in Figure 2, the secondary refrigerant refrigeration system 1 is provided with a gas-phase side second connecting passage 44 that connects the gas phase portion of the condensing-side secondary refrigerant tank 51 to the gas phase portion of the intermediate refrigerant tank 41, a gas-phase side second on-off valve 48 provided in the gas-phase side second connecting passage 44, a liquid-phase side second connecting passage 45 that connects the liquid phase portion of the condensing-side secondary refrigerant tank 51 to the liquid phase portion of the intermediate refrigerant tank 41, and a liquid-phase side second on-off valve 49 provided in the liquid-phase side second connecting passage 45.

[0065] During normal operation of the secondary refrigerant refrigeration system 1 shown in Figure 2, the first on-off valve 46 on the gas phase side, the first on-off valve 47 on the liquid phase side, the second on-off valve 48 on the gas phase side, and the second on-off valve 49 on the liquid phase side are closed.

[0066] In the secondary refrigerant refrigeration system 1 shown in Figure 2, the control device 90, for example, when it determines that the liquid level of the secondary refrigerant in the condensing-side secondary refrigerant tank 51 detected by the level sensor 63 has fallen below a preset threshold, or when it 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, outputs a control signal to the gas-phase-side first on-off valve 46 to open the gas-phase-side first on-off valve 46. As a result, the gas-phase-side first on-off valve 46 opens, and secondary refrigerant gas flows through the gas-phase-side first connecting passage 42, making 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 equal.

[0067] The control device 90 waits for a predetermined time required for 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 to become equal, and then outputs a control signal to the liquid phase-side first on-off valve 47 to open it. As a result, the liquid phase-side first on-off valve 47 opens, and due to the difference in the head volume of the secondary refrigerant liquid between the load-side secondary refrigerant tank 31 and the intermediate refrigerant tank 41, the secondary refrigerant liquid in the load-side secondary refrigerant tank 31 flows into the intermediate refrigerant tank 41 via the liquid phase-side first connecting passage 43.

[0068] When the control device 90 determines that the liquid level of the secondary refrigerant in the load-side secondary refrigerant tank 31, as detected by the level sensor 61, has fallen below a preset threshold for the transfer of the secondary refrigerant liquid, it outputs control signals to the first on-off valve 46 on the gas phase side and the first on-off valve 47 on the liquid phase side to close them. As a result, the first on-off valve 46 on the gas phase side and the first on-off valve 47 on the liquid phase side are closed.

[0069] Next, the control device 90 outputs a control signal to the gas-phase side second on-off valve 48 to open it. As a result, the gas-phase side second on-off valve 48 opens, and secondary refrigerant gas flows through the gas-phase side second connecting passage 44, making the pressures of the gas phase portion of the condensing side secondary refrigerant tank 51 and the gas phase portion of the intermediate refrigerant tank 41 equal.

[0070] The control device 90 waits for a predetermined time required for the pressures of the gas phase portion of the condensing 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 it. As a result, the liquid phase side second on-off valve 49 opens, and the secondary refrigerant liquid in the intermediate refrigerant tank 41 flows into the condensing secondary refrigerant tank 51 via the liquid phase side second connecting passage 45 due to the difference in the head volume of the secondary refrigerant liquid between the intermediate refrigerant tank 41 and the condensing secondary refrigerant tank 51.

[0071] When the control device 90 determines that the liquid level of the secondary refrigerant in the condensing secondary refrigerant tank 51, as detected by the level sensor 63, exceeds a preset threshold for the transfer of the secondary refrigerant liquid, it outputs control signals to the gas-phase second on-off valve 48 and the liquid-phase second on-off valve 49 to close them. As a result, the gas-phase second on-off valve 48 and the liquid-phase second on-off valve 49 are closed, and the transfer of the secondary refrigerant liquid using the intermediate refrigerant tank 41 is completed.

[0072] The operation of the first on-off valve 46 on the gas phase side, the first on-off valve 47 on the liquid phase side, the second on-off valve 48 on the gas phase side, and the second on-off valve 49 on the liquid phase side may be performed automatically as described above, or manually.

[0073] Furthermore, even when it is necessary to transfer the secondary refrigerant liquid from the condensing secondary refrigerant circuit 50 to the load-side secondary refrigerant circuit 30 when, for some reason, the pressure in the condensing secondary refrigerant circuit 50 is lower than the pressure in the load-side secondary refrigerant circuit 30, the secondary refrigerant liquid can be transferred using the intermediate refrigerant tank 41. However, in this case, the height of the load-side secondary refrigerant tank 31 must be set lower than the height of the intermediate refrigerant tank 41, and the height of the condensing secondary refrigerant tank 51 must be set higher than the height of the intermediate refrigerant tank 41. Therefore, it is preferable to appropriately select the height relationship between the load-side secondary refrigerant tank 31, the intermediate refrigerant tank 41, and the condensing secondary refrigerant tank 51 in the facility to which this system is applied.

[0074] The secondary refrigerant refrigeration system 1 shown in Figure 1 includes a liquid phase connecting channel 83 that connects the liquid phase section 34 of the load-side secondary refrigerant circuit 30 and the liquid phase section 54 of the condensing-side secondary refrigerant circuit 50. The secondary refrigerant refrigeration system 1 shown in Figure 2 further includes a liquid phase connection channel 43 and a liquid phase second connection channel 45 in place of the first liquid phase connection channel 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 connection channel 81, and then the supplied secondary refrigerant to be returned from the other secondary refrigerant circuit to the other secondary refrigerant circuit in the form of liquid refrigerant.

[0075] In the secondary refrigerant refrigeration system 1 shown in Figure 2, the height positions of the load-side secondary refrigerant tank 31, the intermediate refrigerant tank 41, and the condensing-side secondary refrigerant tank 51 are set as described above. Therefore, the refrigerant liquid can be returned from the load-side secondary refrigerant tank 31 to the condensing-side secondary refrigerant tank 51 via the intermediate refrigerant tank 41 without the need for a pump.

[0076] This disclosure is not limited to the embodiments described above, but also includes modified forms of the embodiments described above, as well as forms that combine these forms as appropriate.

[0077] The contents described in each of the above embodiments can be understood, for example, as follows: (1) A secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure comprises a primary refrigerant circuit 10 through which a primary refrigerant circulates, and which includes a primary refrigerant compressor 11, a primary refrigerant condenser 13, and a primary refrigerant evaporator 17. A secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure comprises a load-side secondary refrigerant circuit 30 including a load-side evaporator 35 and circulating load-side secondary refrigerant to the load-side evaporator 35 and the primary refrigerant evaporator 17. A secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure comprises a condensing-side condenser 55 and circulating condensing-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, to the condensing-side condenser 55 and the primary refrigerant condenser 13. A secondary refrigerant refrigeration system 1 according to at least one embodiment of the present disclosure comprises a gas phase connecting passage 81 that connects the gas phase section 32 of the load-side secondary refrigerant circuit 30 and the gas phase section 52 of the condensing-side secondary refrigerant circuit 50.

[0078] According to the configuration described in (1) above, 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 condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81.

[0079] (2) In some embodiments, the configuration of (1) above may include an inlet shut-off valve 71 capable of shutting off the inlet refrigerant flow path 37i connected to the inlet of the load-side evaporator 35, and an outlet shut-off valve 72 capable of shutting off the outlet refrigerant flow path 37o connected to the outlet of the load-side evaporator 35.

[0080] According to the configuration described in (2) above, 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 condensing-side secondary refrigerant by closing the inlet-side shut-off valve 71 and the outlet-side shut-off valve 72, thereby enabling efficient defrosting.

[0081] (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 is preferably downstream of the inlet-side shut-off valve 71 and upstream of the outlet-side shut-off valve 72.

[0082] According to the configuration described in (3) above, 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 condensing-side secondary refrigerant by closing the inlet-side shut-off valve 71 and the outlet-side shut-off valve 72, thereby enabling efficient defrosting.

[0083] (4) In some embodiments, the configuration of (1) to (3) above may be provided with a connecting passage shut-off valve (first on-off valve 73, second on-off valve 74) capable of closing the gas phase connecting passage 81.

[0084] According to the configuration in (4) above, if it is not necessary to supply the secondary refrigerant from either the load-side secondary refrigerant circuit 30 or the condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81, the flow of secondary refrigerant between the load-side secondary refrigerant circuit 30 and the condensing-side secondary refrigerant circuit 50 can be blocked by closing the connection passage shut-off valves (first shut-off valve 73, second shut-off valve 74).

[0085] (5) In some embodiments, the configuration of (1) to (4) above may include a liquid phase connecting passage 83 that connects the liquid phase portion 34 of the load-side secondary refrigerant circuit 30 and the liquid phase portion 54 of the condensing-side secondary refrigerant circuit 50.

[0086] According to the configuration described in (5) above, the secondary refrigerant from either the load-side secondary refrigerant circuit 30 or the condensing-side secondary refrigerant circuit 50 can be supplied to the other secondary refrigerant circuit via the gas phase connection channel 81, and then the supplied secondary refrigerant can be returned from the other secondary refrigerant circuit to the other secondary refrigerant circuit in the form of a liquid refrigerant.

[0087] (6) In some embodiments, the configuration of (5) above may include a load-side secondary refrigerant tank 31 provided in the load-side secondary refrigerant circuit 30, a condensing-side secondary refrigerant tank 51 provided in the condensing-side secondary refrigerant circuit 50, and an intermediate refrigerant tank 41 provided in the middle of the liquid phase connection passage (liquid phase-side first connection passage 43, liquid phase-side second connection passage 45). The height of the load-side secondary refrigerant tank 31 is preferably higher than the height of the intermediate refrigerant tank 41, and the height of the condensing-side secondary refrigerant tank 51 is preferably lower than the height of the intermediate refrigerant tank 41.

[0088] According to the configuration described in (6) above, the refrigerant liquid can be returned from the load-side secondary refrigerant tank 31 to the condensing-side secondary refrigerant tank 51 via the intermediate refrigerant tank 41 without the need for a pump.

[0089] (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 the air.

[0090] According to the configuration in (7) above, the load-side evaporator 35 can be used as an air cooler for cooling the air. Furthermore, according to the configuration in (7) above, defrosting of the air cooler becomes easier.

[0091] (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 through which a primary refrigerant circulates, and which is equipped with a primary refrigerant compressor 11, a primary refrigerant condenser 13, and a primary refrigerant evaporator 17. The secondary refrigerant refrigeration system 1 includes a load-side evaporator 35 and a load-side secondary refrigerant circuit 30 that circulates load-side secondary refrigerant to the load-side evaporator 35 and the primary refrigerant evaporator 17. The secondary refrigerant refrigeration system 1 includes a condensing-side condenser 55 and a condensing-side secondary refrigerant circuit 50 that circulates condensing-side secondary refrigerant, which is the same refrigerant as the load-side secondary refrigerant, to the condensing-side condenser 55 and the primary refrigerant condenser 13. The secondary refrigerant refrigeration system 1 includes a gas phase connecting passage 81 that connects the gas phase section 32 of the load-side secondary refrigerant circuit 30 and the gas phase section 52 of the condensing-side secondary refrigerant circuit 50. In a secondary refrigerant pressure adjustment method according to at least one embodiment of the present disclosure, the pressure of the load-side evaporator 35 is adjusted by supplying the secondary refrigerant from either the load-side secondary refrigerant circuit 30 or the condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81.

[0092] According to the method described in (8) above, 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 condensing-side secondary refrigerant circuit 50 to the other secondary refrigerant circuit via the gas phase connection passage 81. [Explanation of Symbols]

[0093] 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 35 Load-side evaporator 41 Intermediate refrigerant tank 50 Condensing side secondary refrigerant circuit 51 Condensing side secondary refrigerant tank 52 Gas phase section 54 Liquid phase 55 Condensing side condenser 71 Inlet-side shut-off valve 72 Outlet shut-off valve 81 Gas phase connection channel 83 Liquid phase connection channel

Claims

1. A primary refrigerant circuit is provided, in which a primary refrigerant circulates, and a primary refrigerant compressor, a primary refrigerant condenser for transferring heat to the condensing secondary refrigerant, and a primary refrigerant evaporator for removing heat from the load-side secondary refrigerant, which is the same refrigerant as the condensing secondary refrigerant. A load-side secondary refrigerant circuit includes a load-side evaporator for evaporating the load-side secondary refrigerant, and circulates the load-side secondary refrigerant to the load-side evaporator and the primary refrigerant evaporator. A condensing secondary refrigerant circuit includes a condensing condenser for condensing the condensing secondary refrigerant, and circulates the condensing secondary refrigerant to the condensing condenser and the primary refrigerant condenser. A gas phase connecting passage that connects the gas phase portion of the load-side secondary refrigerant circuit and the gas phase portion of the condensing-side secondary refrigerant circuit, A secondary refrigerant refrigeration system equipped with a refrigerant.

2. An inlet-side shut-off valve capable of closing the inlet-side refrigerant flow path connected to the inlet of the load-side evaporator, An outlet-side shut-off valve capable of closing the outlet-side refrigerant flow path connected to the outlet of the load-side evaporator, Equipped with, The secondary refrigerant refrigeration system according to claim 1.

3. The connection position of the gas phase connection passage 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. The secondary refrigerant refrigeration system according to claim 2.

4. A connecting channel shut-off valve capable of closing the gas phase connecting channel, Equipped with, A secondary refrigerant refrigeration system according to any one of claims 1 to 3.

5. A liquid phase connecting channel that connects the liquid phase portion of the load-side secondary refrigerant circuit and the liquid phase portion of the condensing-side secondary refrigerant circuit, Equipped with, A secondary refrigerant refrigeration system according to any one of claims 1 to 3.

6. A load-side secondary refrigerant tank provided in the load-side secondary refrigerant circuit, A condensing secondary refrigerant tank provided in the condensing secondary refrigerant circuit, An intermediate refrigerant tank is provided in the middle of the liquid phase connection channel, Equipped with, The height of the load-side secondary refrigerant tank is higher than the height of the intermediate refrigerant tank. The height of the condensing secondary refrigerant tank is lower than the height of the intermediate refrigerant tank. The secondary refrigerant refrigeration system according to claim 5.

7. The load-side evaporator is an air cooler for cooling the air. A secondary refrigerant refrigeration system according to any one of claims 1 to 3.

8. A method for adjusting the pressure of a secondary refrigerant in a secondary refrigerant refrigeration system, The aforementioned secondary refrigerant refrigeration system is A primary refrigerant circuit is provided, in which a primary refrigerant circulates, and a primary refrigerant compressor, a primary refrigerant condenser for transferring heat to the condensing secondary refrigerant, and a primary refrigerant evaporator for removing heat from the load-side secondary refrigerant, which is the same refrigerant as the condensing secondary refrigerant. A load-side secondary refrigerant circuit includes a load-side evaporator for evaporating the load-side secondary refrigerant, and circulates the load-side secondary refrigerant to the load-side evaporator and the primary refrigerant evaporator. A condensing secondary refrigerant circuit includes a condensing condenser for condensing the condensing secondary refrigerant, and circulates the condensing secondary refrigerant to the condensing condenser and the primary refrigerant condenser. A gas phase connecting passage that connects the gas phase portion of the load-side secondary refrigerant circuit and the gas phase portion of the condensing-side secondary refrigerant circuit, Equipped with, The pressure of the load-side evaporator is adjusted by supplying the secondary refrigerant from either the load-side secondary refrigerant circuit or the condensing-side secondary refrigerant circuit to the other secondary refrigerant circuit via the gas phase connection passage. A method for adjusting the pressure of a secondary refrigerant.

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