Refrigeration system

Abstract

This refrigeration system is provided with a refrigerated warehouse comprising a refrigerated space, and a refrigerator able to cool gas drawn in from the refrigerated space. The refrigerator comprises: an inlet line for guiding gas from the refrigerated space to a compressor; a compressed gas line for guiding gas from the compressor to a turbine; an outlet line for guiding gas from the turbine to the refrigerated space; and a heat exchanger for exchanging heat between the gas flowing through the inlet line and the gas flowing through the compressed gas line. The inlet line comprises an inlet-side inner pipe that is provided to the refrigerated space and has an air intake. The refrigeration system is further provided with a warm air line for guiding compressed gas flowing upstream of the heat exchanger in the compressed gas line to the refrigerated space, and a warm air flow rate adjustment device able to adjust the flow rate of compressed gas flowing through the warm air line. The warm air line comprises a warm air line-side inner pipe that is provided to the refrigerated space and has an outlet for discharging circulating gas toward the air intake.

Description

Refrigeration system

[0001] The present disclosure relates to a refrigeration system. The present application claims priority based on Japanese Patent Application No. 2025-049526 filed with the Japan Patent Office on March 25, 2025, the content of which is incorporated herein by reference.

[0002] Patent Document 1 discloses a refrigerated warehouse having therein a refrigeration space that is an object to be cooled, and an air refrigerant refrigeration apparatus for cooling air extracted from the refrigeration space. Patent Document 1 discloses that a defroster is provided in a pipe connecting an expansion turbine and the refrigerated warehouse in order to remove frost formed by condensation in an air refrigerant that has been adiabatically expanded by the expansion turbine and cooled to a low temperature.

[0003] Japanese Patent No. 4241699

[0004] If a device for removing drain generated by a defroster or defrosting is provided in a cycle for extracting and circulating air present in the refrigeration space of a refrigerator, there is a risk of causing pressure loss in the refrigerator. Further, even if a device for removing drain generated by a defroster or defrosting is provided in the above cycle, frost adhering to air inlets and outlets provided in the refrigeration space cannot be removed, so it is necessary to periodically manually remove frost adhering to the inlets and outlets, which poses a problem in terms of maintainability of defrosting of the refrigerator.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a refrigeration system capable of improving the maintainability of defrosting of a refrigerator.

[0006] A refrigeration system according to at least one embodiment of the present disclosure comprises a cold storage warehouse having a cold storage space to be cooled, and at least one chiller configured to cool a circulating gas drawn in from the cold storage space, wherein the chiller includes: a compressor configured to compress the circulating gas; a turbine configured to expand the circulating gas; an inlet line for leading the circulating gas from the cold storage space to the compressor; a compressed gas line for leading the compressed gas, which is the circulating gas compressed by the compressor, to the turbine; an outlet line for leading the circulating gas, which has been expanded by the turbine, to the cold storage space; and a heat exchanger configured to perform heat exchange between the circulating gas flowing through the inlet line and the compressed gas flowing through the compressed gas line, wherein the inlet line includes an inlet-side inner pipe provided in the cold storage space and having a suction port for drawing in the circulating gas from the cold storage space, and the refrigeration system includes a warm air line for drawing out the compressed gas flowing upstream of the heat exchanger in the compressed gas line and leading it to the cold storage space. The system further comprises a warm air flow rate adjustment device configured to adjust the flow rate of the compressed gas flowing through the warm air line, wherein the warm air line includes a warm air line side inner pipe provided in the refrigeration space and having a discharge port for discharging the circulating gas toward the intake port.

[0007] According to at least one embodiment of the present disclosure, a refrigeration system is provided that can improve the maintainability of defrosting the refrigeration unit.

[0008] This is a schematic diagram illustrating a refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram illustrating a modified example of the refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram illustrating a modified example of the refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram showing the outlet side inner pipe and outlet side drain receiving section shown in Figures 1 to 3 viewed from above. This is a schematic diagram illustrating a modified example of the refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram showing a modified example of the refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram showing the nozzle, outlet side inner pipe and outlet side drain receiving section of the outlet side water spraying device shown in Figure 6 viewed from above. This is a schematic diagram illustrating a modified example of the refrigeration system according to the first embodiment of this disclosure. This is a schematic diagram illustrating a refrigeration system according to the second embodiment of this disclosure. This is a schematic diagram showing the inlet side inner pipe and inlet side drain receiving section shown in Figure 9 viewed from above. This is a schematic diagram illustrating a refrigeration system according to the second embodiment of this disclosure. Figure 12 is a schematic diagram showing the nozzle, inlet side inner pipe and inlet side drain receiving section of the inlet side water spraying device shown in Figure 11 viewed from above. This is a schematic diagram illustrating a refrigeration system according to a second embodiment of the present disclosure. This is a schematic diagram illustrating a refrigeration system according to a first embodiment of the present disclosure. This is a schematic diagram illustrating a refrigeration system according to a first embodiment of the present disclosure. This is a schematic diagram illustrating a refrigeration system according to a first embodiment of the present disclosure. This is an explanatory diagram for illustrating the intake filter shown in Figure 16. This is an explanatory diagram for illustrating the compressor filter shown in Figure 16. This is a schematic diagram illustrating a refrigeration system according to a first embodiment of the present disclosure. This is a schematic diagram illustrating a refrigeration system according to a first embodiment of the present disclosure.

[0009] 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.

[0010] (Refrigeration System) Figure 1 is a schematic diagram showing a refrigeration system 1 according to a first embodiment of the present disclosure. As shown in Figure 1, some embodiments of the refrigeration system 1 include a cold storage warehouse 2 having a cold storage space 20 to be cooled inside, and at least one refrigerator 3 configured to cool circulating gas drawn in from the cold storage space 20. The refrigerator 3 cools the cold storage space 20 by cooling the circulating gas drawn in from the cold storage space 20 and then returning it to the cold storage space 20.

[0011] (Refrigeration Unit) The refrigerator unit 3, as shown in Figure 1, includes a compressor 41 configured to compress the circulating gas, a turbine 42 configured to expand the circulating gas, an inlet line 5, a compressed gas line 6, an outlet line 7, a heat exchanger 8, a warm air line 11, and a warm air flow rate adjustment device 12.

[0012] (Inlet line, compressed gas line, outlet line) The inlet line 5, as shown in Figure 1, is a flow path for guiding circulating gas from the refrigerated space 20 to the compressor 41. The compressed gas line 6, as shown in Figure 1, is a flow path for guiding the compressed gas, which is the circulating gas compressed by the compressor 41, to the turbine 42. The outlet line 7 is a flow path for guiding the circulating gas, which has been expanded by the turbine 42, back to the refrigerated space 20.

[0013] As shown in Figure 1, the inlet line 5 includes an inlet-side inner pipe 51 provided in the refrigeration space 20 and an inlet-side outer pipe 52 provided outside the refrigerated warehouse 2 (refrigeration space 20). The inlet-side inner pipe 51 has a suction port 53 (opening) for drawing circulating gas from the refrigeration space 20 into the interior of the inlet-side inner pipe 51. The suction port 53 is formed at the upstream end of the cylindrical inlet-side inner pipe 51. The upstream end of the inlet-side outer pipe 52 is connected to the downstream end of the inlet-side inner pipe 51, and its downstream end is connected to the heat exchanger 8.

[0014] The compressed gas line 6 is located outside the cold storage warehouse 2 (cold space 20). The upstream end of the compressed gas line 6 is connected to the compressor 41, and the downstream end is connected to the turbine 42.

[0015] As shown in Figure 1, the outlet line 7 includes an outlet-side inner pipe 71 provided in the refrigerated space 20 and an outlet-side outer pipe 72 provided outside the refrigerated warehouse 2 (refrigerated space 20). The outlet-side inner pipe 71 has a blowout outlet 73 (opening) for guiding circulating gas from inside the outlet-side inner pipe 71 into the refrigerated space 20. The blowout outlet 73 is formed at the downstream end of the cylindrical outlet-side inner pipe 71. The outlet-side outer pipe 72 has its upstream end connected to the turbine 42 and its downstream end connected to the upstream end of the outlet-side inner pipe 71.

[0016] (Turbomachinery) In the illustrated embodiment, the refrigerator 3 described above includes a turbomachinery 4, as shown in Figure 1. The turbomachinery 4 includes the compressor 41 described above, the turbine 42 described above, a rotating shaft 43, and an electric motor 44, as shown in Figure 1. The rotating shaft 43 is connected to the compressor 41 and the turbine 42. The electric motor 44 is configured to generate a rotational force that rotates the rotating shaft 43.

[0017] In the illustrated embodiment, the impeller of the compressor 41 is attached to one side of the rotating shaft 43, and the wheel (turbine wheel) of the turbine 42 is attached to the other side of the rotating shaft 43. In other words, the compressor 41 and the turbine 42 are arranged coaxially with each other via the rotating shaft 43, which is the output shaft of the electric motor 44, and are connected to the rotating shaft 43, respectively.

[0018] The electric motor 44 is supplied with current from a power source such as a generator (not shown), and is driven by the current supplied from the power source to drive (rotate) the rotating shaft 43, the compressor 41, and the turbine 42.

[0019] By driving the compressor 41, the gas in the refrigerated space 20 is drawn into the inlet line 5 via the intake port 53 and guided to the compressor 41. The compressor 41 is configured to compress the circulating gas, which is the gas drawn in from the refrigerated space 20 via the intake port 53. The circulating gas compressed by the compressor 41 is heated and pressurized higher than before it was introduced into the compressor 41, becoming a gas at a relatively high temperature and pressure.

[0020] The compressed gas, which is a circulating gas compressed by the compressor 41, is led to the turbine 42 via the compressed gas line 6. The turbine 42 is configured to expand the compressed gas that has been led to it. The circulating gas expanded by the turbine 42 is cooled and depressurized compared to before it was introduced into the turbine 42, becoming a relatively low-temperature, low-pressure fluid.

[0021] (Heat Exchanger) The heat exchanger 8 is configured to exchange heat between the circulating gas flowing through the inlet line 5 and the compressed gas flowing through the compressed gas line 6. The heat exchanger 8 is configured so that heat is transferred between two gases with different temperatures separated by a heat transfer wall. Through heat transfer in the heat exchanger 8, the compressed gas flowing through the compressed gas line 6 is cooled and the circulating gas flowing through the inlet line 5 is heated. The circulating gas heated by the heat exchanger 8 is introduced into the compressor 41. The compressed gas cooled by the heat exchanger 8 is introduced into the turbine 42.

[0022] (Cooler) In the illustrated embodiment, the refrigerator 3 described above further includes a cooler 9 configured to cool the compressed gas flowing upstream of the heat exchanger 8 (compressor 41 side) of the compressed gas line 6. The cooler 9 is configured to exchange heat between the compressed gas flowing upstream of the heat exchanger 8 of the compressed gas line 6 and a coolant (for example, water) that is colder than the compressed gas. The cooler 9 is configured so that two fluids with different temperatures (compressed gas and coolant) transfer heat across a heat transfer wall.

[0023] Heat transfer in the cooler 9 cools the compressed gas flowing upstream of the heat exchanger 8 in the compressed gas line 6. The compressed gas cooled by the cooler 9 is then introduced into the heat exchanger 8 through the compressed gas line 6.

[0024] In the illustrated embodiment, the refrigerator 3 includes a coolant line 91 for circulating coolant and a cooling device 92 for cooling the coolant flowing through the coolant line 91. The coolant line 91 is a passage for returning the coolant taken from the cooler 9 to the cooler 9. The coolant line 91 is provided with a coolant pump 93 for supplying coolant in the coolant line 91 and a radiator 94. The cooling device 92 includes a radiator 94 and a fan 95 for air-cooling the radiator 94.

[0025] The coolant, which has been heated by heat transfer in the cooler 9, is guided to the coolant line 91 by the coolant pump 93, cooled by the cooling system 92 including the radiator 94, and then guided back to the cooler 9.

[0026] (Warm air line) The warm air line 11 is a flow path for extracting compressed gas (circulating gas) flowing upstream of the heat exchanger 8 of the compressed gas line 6 and guiding it to the refrigerated space 20. The warm air line 11 includes a warm air line side inner pipe 111 provided in the refrigerated space 20 and a warm air line side outer pipe 112 provided outside the refrigerated warehouse 2 (refrigerated space 20). The warm air line side inner pipe 111 has a discharge port 113 (opening) for discharging circulating gas from inside the warm air line side inner pipe 111 toward the intake port 53. The discharge port 113 is formed at the downstream end of the cylindrical warm air line side inner pipe 111.

[0027] In the illustrated embodiment, the upstream end of the warm air line 11 is connected upstream of the cooler 9 of the compressed gas line 6. In this case, by connecting the upstream end of the warm air line 11 upstream of the cooler 9 of the compressed gas line 6, the refrigeration system 1 can circulate high-temperature circulating gas (warm air) in the warm air line 11 compared to when it is connected between the cooler 9 and the heat exchanger 8 of the compressed gas line 6, thereby promoting defrosting of the chiller 3 by the warm air. In some other embodiments, the upstream end of the warm air line 11 may be connected between the cooler 9 and the heat exchanger 8 of the compressed gas line 6.

[0028] In the embodiment shown in Figure 1, the warm air line side outer pipe 112 has its upstream end connected upstream of the cooler 9 of the compressed gas line 6, and its downstream end connected to the upstream end of the warm air line side inner pipe 111.

[0029] In the embodiment shown in Figure 1, the warm air line side inner pipe 111 is positioned along the inlet side inner pipe 51 for at least a portion of its length. The warm air line side inner pipe 111 is positioned such that the discharge port 113 faces the suction port 53, and the extension line LA1, which extends the central axis of the discharge port 113 in the discharge direction, passes through the suction port 53.

[0030] (Warm air flow rate adjustment device) The warm air flow rate adjustment device 12 is configured to adjust the flow rate of compressed gas (circulating gas) flowing through the warm air line 11. In the illustrated embodiment, the warm air flow rate adjustment device 12 is a flow rate adjustment valve 121 provided in the warm air line 11. The flow rate adjustment valve 121 is configured to adjust the flow rate of circulating gas guided downstream of the flow rate adjustment valve 121 (towards the discharge port 113) via the warm air line 11 by changing the opening degree of a valve body located in the warm air line 11. The flow rate adjustment valve 121 may be an on-off valve whose opening degree can be adjusted to fully closed and fully open, or it may be an opening degree adjustment valve whose opening degree can be adjusted to fully closed, fully open and at least one intermediate opening degree between these.

[0031] (Opening and closing of valves during normal operation) During normal operation of the chiller 3, the flow control valve 121 is closed. During normal operation of the chiller 3, the circulating gas flows through the inlet line 5, the compressed gas line 6, and the outlet line 7, without passing through the warm air line 11.

[0032] (Opening and closing of valves during defrost operation) During defrost operation of the chiller 3, the flow control valve 121 is open. During defrost operation of the chiller 3, warm air (circulating gas) that has become relatively high temperature and pressure by being compressed by the compressor 41 passes through the warm air line 11 and is led to the refrigerated space 20 from the discharge port 113. The warm air (circulating gas) led to the refrigerated space 20 from the discharge port 113 is drawn into the inlet inner pipe 51 via the suction port 53, flows downstream through the inlet line 5, compressed gas line 6 and outlet line 7, and is then led to the refrigerated space 20 via the blow outlet 73. The warm air flowing through the inlet line 5, compressed gas line 6 and outlet line 7 melts the frost attached to the chiller 3, especially the inlet line 5 including the inlet inner pipe 51 and the outlet line 7 including the outlet inner pipe 71.

[0033] In this embodiment, the refrigeration system 1 discharges warm air (relatively high temperature and high pressure compressed gas) flowing through the warm air line 11 from the discharge port 113 toward the suction port 53, thereby drawing the warm air into the inlet inner pipe 51 via the suction port 53. The refrigeration system 1 can melt the frost adhering to the chiller 3, particularly the inlet line 5 including the inlet inner pipe 51 and the outlet line 7 including the outlet inner pipe 71, with the warm air drawn in through the suction port 53. In this embodiment, the refrigeration system 1 can melt the frost adhering to the inlet inner pipe 51 and the outlet inner pipe 71 located inside the cold storage warehouse 2 when melting the frost adhering to the chiller 3, thereby improving the maintainability of defrosting the chiller 3.

[0034] Figures 2 and 3 are schematic diagrams illustrating modified examples of the refrigeration system 1 according to the first embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figures 2 and 3, the warm air line 11 described above includes a first warm air line 13 and a second warm air line 14 (14A, 14B).

[0035] (First warm air line) The first warm air line 13 is a flow path that extracts circulating gas from the upstream side of the heat exchanger 8 of the compressed gas line 6 and guides it to the downstream side of the heat exchanger 8 of the compressed gas line 6.

[0036] In the illustrated embodiment, the upstream end of the first warm air line 13 is connected upstream of the cooler 9 of the compressed gas line 6. In this case, by connecting the upstream end of the first warm air line 13 upstream of the cooler 9 of the compressed gas line 6, the refrigeration system 1 can circulate high-temperature circulating gas (warm air) in the first warm air line 13 compared to when it is connected between the cooler 9 and the heat exchanger 8, thereby promoting defrosting of the chiller 3 by the warm air. In some other embodiments, the upstream end of the first warm air line 13 may be connected between the cooler 9 and the heat exchanger 8 of the compressed gas line 6.

[0037] (Second warm air line) The second warm air line 14 (14A) has a warm air line side inner pipe 111 and a warm air line side outer pipe 112. In the embodiment shown in Figure 2, the upstream end of the warm air line side outer pipe 112 of the second warm air line 14 (14A) is connected downstream of the heat exchanger 8 of the compressed gas line 6. In the embodiment shown in Figure 3, the upstream end of the warm air line side outer pipe 112 of the second warm air line 14 (14B) is connected to the outlet side outer pipe 72 (outlet line 7).

[0038] The flow control valve 121 provided in the warm air line 11 as described above includes a first warm air flow control valve 122 provided in the first warm air line 13 and a second warm air flow control valve 123 provided in the second warm air line 14 (14A, 14B).

[0039] (Opening and closing of valves during normal operation) During normal operation of the chiller 3, the first warm air flow control valve 122 and the second warm air flow control valve 123 are closed. During normal operation of the chiller 3, the circulating gas flows through the inlet line 5, the compressed gas line 6 and the outlet line 7, without passing through the first warm air line 13 and the second warm air line 14.

[0040] (Opening and closing of valves during defrosting operation on the turbine side) During defrosting operation on the turbine 42 side of the chiller 3, the second warm air flow control valve 123 is closed and the first warm air flow control valve 122 is open. During defrosting operation on the turbine 42 side of the chiller 3, warm air (compressed gas) that has become relatively high temperature and pressure due to compression by the compressor 41 is guided through the first warm air line 13 to the turbine 42 and outlet line 7, thereby melting the frost attached to the turbine 42 and outlet line 7.

[0041] (Opening and closing of valves during defrost operation on the heat exchanger side) During defrost operation on the heat exchanger 8 side of the chiller 3, the first warm air flow control valve 122 and the second warm air flow control valve 123 are open. During defrost operation on the heat exchanger 8 side of the chiller 3, warm air (compressed gas) that has become relatively high temperature and pressure due to compression by the compressor 41 is guided to the refrigerated space 20 from the discharge port 113 after passing through the first warm air line 13 and the second warm air line 14. The warm air (circulating gas) guided to the refrigerated space 20 from the discharge port 113 is drawn into the inlet side inner pipe 51 via the suction port 53, flows downstream through the inlet line 5, compressed gas line 6 and outlet line 7, and is then guided to the refrigerated space 20 via the blow outlet 73. The warm air flowing through the inlet line 5, compressed gas line 6 and outlet line 7 melts the frost attached to the chiller 3, especially the inlet line 5 and the heat exchanger 8.

[0042] In this embodiment, the refrigeration system 1 includes a first warm air line 13 and a second warm air line 14 in the warm air line 11, which allows the path of warm air in the chiller 3 to be changed. This enables defrosting operation on the turbine 42 side of the chiller 3 and defrosting operation on the heat exchanger 8 side of the chiller 3. During defrosting operation on the turbine 42 side of the chiller 3, the warm air passing through the first warm air line 13 (but not the second warm air line 14) can melt the frost attached to the turbine 42 and the outlet line 7. During defrosting operation on the heat exchanger 8 side of the chiller 3, the warm air passing through the first warm air line 13 and the second warm air line 14 can melt the frost attached to the inlet line 5 and the heat exchanger 8.

[0043] As shown in FIGS. 1 to 3, a refrigeration system 1 according to some embodiments includes the above-described refrigerated warehouse 2, the above-described refrigerator 3, an outlet-side drain receiving portion 15, and an outlet-side drain line 16.

[0044] (Outlet-side Drain Receiver) FIG. 4 is a schematic top view of an outlet-side inner pipe 71 and the outlet-side drain receiving portion 15 shown in FIGS. 1 to 3. The outlet-side drain receiving portion 15 is disposed below the outlet-side inner pipe 71 so as to receive drain flowing down from the outlet-side inner pipe 71. As shown in FIGS. 1 to 3, the outlet-side drain receiving portion 15 has an outlet-side recess 151 that opens upward. The air outlet 73 of the outlet-side inner pipe 71 is disposed inside the outer peripheral edge 152 of the outlet-side recess 151 in the top view as shown in FIG. 4. The drain flowing down from the air outlet 73 of the outlet-side inner pipe 71 is received by the outlet-side recess 151.

[0045] In the illustrated embodiment, the outlet-side drain receiving portion 15 extends along the horizontal direction, and includes a bottom portion 154 having an upper surface 153 that constitutes the bottom surface of the outlet-side recess 151, and a cylindrical projecting portion 155 that projects upward from the outer peripheral edge of the bottom portion 154. The projecting portion 155 has an inner peripheral surface 156 that constitutes the inner wall surface of the outlet-side recess 151. A drain discharge hole 157 for discharging drain is formed in the upper surface 153 of the bottom portion 154.

[0046] (Outlet-side Drain Line) The outlet-side drain line 16 is a flow path for guiding drain from the outlet-side drain receiving portion 15 to the outside of the refrigerated warehouse 2. In the illustrated embodiment, the outlet-side drain line 16 has an upstream end connected to the drain discharge hole 157, and a downstream end disposed outside the refrigerated warehouse 2. The drain that has flowed down into the outlet-side recess 151 flows through the outlet-side drain line 16 and is discharged to the outside of the refrigerated warehouse 2.

[0047] The refrigeration system 1 according to the present embodiment can guide drain generated by melting frost adhering to the refrigerator 3, particularly the inlet-side inner pipe 51 and the outlet-side inner pipe 71 arranged inside the refrigeration warehouse 2, to the refrigeration space 20 via the outlet-side inner pipe 71. The refrigeration system 1 can discharge the drain guided to the refrigeration space 20 via the outlet-side inner pipe 71 to the outside of the refrigeration warehouse 2 by means of the outlet-side drain receiving portion 15 and the outlet-side drain line 16. In the refrigeration system 1 according to the present embodiment, it is not necessary to provide a mechanism for recovering drain that causes pressure loss in the flow path through which the circulating gas flows in the refrigerator 3, so pressure loss in the refrigerator 3 can be suppressed.

[0048] (Inclination of outlet-side inner pipe) FIG. 5 is a diagram schematically illustrating a modified example of the refrigeration system 1 according to the first embodiment of the present disclosure. In the refrigeration system 1 according to some embodiments, as shown in FIG. 5, at least a part of the outlet-side inner pipe 71 described above is inclined so as to be positioned lower toward the air outlet 73. At least a part of the outlet-side inner pipe 71 is inclined with respect to the horizontal direction so as to gradually become lower toward the downstream end where the air outlet 73 is formed. In the embodiment shown in FIG. 5, the outlet-side inner pipe 71 is inclined from the upstream end to the downstream end thereof, and does not have any portion extending along the horizontal direction.

[0049] In the refrigeration system 1 according to the present embodiment, by inclining the outlet-side inner pipe 71 so as to be positioned lower toward the air outlet 73, the drain inside the outlet-side inner pipe 71 easily flows down toward the air outlet 73, and the drain discharge performance of the outlet-side inner pipe 71 can be improved. Note that in some other embodiments, the outlet-side inner pipe 71 may extend along the horizontal direction. The modified example of the refrigeration system 1 shown in FIG. 5 is applicable to the refrigeration system 1 shown in FIGS. 1 to 4.

[0050] (Outlet-side water spraying device) FIG. 6 is a diagram schematically illustrating a modified example of the refrigeration system 1 according to the first embodiment of the present disclosure. The refrigeration system 1 according to some embodiments includes, as shown in FIG. 5, an outlet-side water spraying device 31 configured to spray water from above onto the outlet-side drain receiving portion 15 described above.

[0051] The outlet-side water spraying device 31 has a nozzle 311 for spraying water, and sprays water supplied by a pump (not shown) or the like towards the outlet-side drain receiving section 15 located below. The nozzle 311 may be positioned above the outlet-side inner pipe 71, and may spray water onto the portion of the outlet-side inner pipe 71 including the outlet 73. The water sprayed by the outlet-side water spraying device 31 may be at room temperature (0°C to 40°C) or it may be hot water above room temperature.

[0052] Figure 7 is a schematic view from above of the nozzle 311, outlet inner pipe 71, and outlet drain receiving section 15 of the outlet water spraying device 31 shown in Figure 6. The area where the water sprayed by the outlet water spraying device 31 is diffused (water diffusion area WA1) is located inside the outer edge 152 of the outlet recess 151 at the height of the upper end (outer edge 152) of the outlet recess 151, as shown in Figure 7. In this case, the water sprayed by the outlet water spraying device 31 is received in the outlet recess 151.

[0053] In this embodiment, the refrigeration system 1 can melt frost adhering to the outlet drain receiving section 15 by spraying water from above onto the outlet drain receiving section 15 using the outlet water spraying device 31. Modifications of the refrigeration system 1 shown in Figures 6 and 7 are applicable to the refrigeration system 1 shown in Figures 1 to 5.

[0054] (Outlet side heating heater) Figure 8 is a schematic diagram showing a modified example of the refrigeration system 1 according to the first embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figure 8, an outlet side heating heater 32 is provided which is configured to heat the outlet side drain receiving section 15 described above.

[0055] Examples of outlet-side heating heaters 32 include resistance heaters and induction heaters. In the embodiment shown in Figure 8, the outlet-side heating heater 32 has a resistor 321, such as a metal wire, that generates heat when energized. The resistor 321 may be housed in a space formed inside the outlet-side drain receiving section 15 (see Figure 8), or it may be attached to the outer surface of the outlet-side drain receiving section 15. The outlet-side heating heater 32 generates heat in the resistor 321 by current supplied to the resistor 321 from a power source (not shown), and the generated heat heats the outlet-side drain receiving section 15 by radiation, convection, and conduction.

[0056] In this embodiment, the refrigeration system 1 can melt frost adhering to the outlet drain receiving section 15 by heating the outlet drain receiving section 15 with the outlet heating heater 32. Note that a modified version of the refrigeration system 1 shown in Figure 8 is applicable to the refrigeration system 1 shown in Figures 1 to 5.

[0057] (Refrigeration System According to a Second Embodiment) Figure 9 is a schematic diagram showing a refrigeration system 1 according to a second embodiment of the present disclosure. As shown in Figure 9, some embodiments of the refrigeration system 1 include the above-described refrigerated warehouse 2, the above-described at least one refrigeration unit 3, the above-described outlet drain receiving section 15, the above-described outlet drain line 16, the above-described inlet drain receiving section 17, and the inlet drain line 18. The refrigeration system 1 according to the second embodiment shown in Figure 9 differs from the refrigeration system 1 according to the first embodiment shown in Figure 1 in that it includes an inlet drain receiving section 17 and an inlet drain line 18.

[0058] (Inlet side drain receiver) Figure 10 is a schematic view of the inlet side inner pipe 51 and the inlet side drain receiver 17 shown in Figure 9, viewed from above. The inlet side drain receiver 17 is positioned below the inlet side inner pipe 51 to receive the drain flowing down from the inlet side inner pipe 51. As shown in Figures 9 and 10, the inlet side drain receiver 17 has an inlet side recess 171 that opens upward. The suction port 53 of the inlet side inner pipe 51 is positioned inside the outer peripheral edge 172 of the inlet side recess 171 when viewed from above as shown in Figure 9. The drain flowing down from the suction port 53 of the inlet side inner pipe 51 is received by the inlet side recess 171.

[0059] In the illustrated embodiment, the inlet-side drain receiving portion 17 includes a bottom portion 174 that extends horizontally and has an upper surface 173 that constitutes the bottom surface of the inlet-side recess 171, and a cylindrical projection 175 that protrudes upward from the outer peripheral edge of the bottom portion 174. The projection 175 has an inner circumferential surface 176 that constitutes the inner wall surface of the inlet-side recess 171. A drain discharge hole 177 for discharging drain is formed in the upper surface 173 of the bottom portion 174.

[0060] (Inlet side drain line) The inlet side drain line 18 is a flow path for guiding drain from the inlet side drain receiving section 17 to the outside of the cold storage warehouse 2. In the illustrated embodiment, the upstream end of the inlet side drain line 18 is connected to the drain discharge hole 177, and the downstream end is located outside the cold storage warehouse 2. The drain that flows down into the inlet side recess 171 flows through the inlet side drain line 18 and is discharged to the outside of the cold storage warehouse 2.

[0061] In this embodiment, the refrigeration system 1 is able to receive the drain that flows down from the inlet inner pipe 51, which is generated by melting frost adhering to the inlet inner pipe 51, via the inlet-side drain receiving section 17, thereby preventing the drain from falling onto the objects to be frozen placed in the refrigeration space 20. The inlet-side drain line 18 allows the drain received by the inlet-side drain receiving section 17 to be discharged to the outside of the refrigeration warehouse 2. Note that the refrigeration system 1 shown in Figure 9 can be modified versions of the refrigeration system 1 shown in Figures 2 to 8.

[0062] (Inlet side water spraying device) Figure 11 is a schematic diagram showing a modified example of a refrigeration system according to a second embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figure 11, in addition to the configuration of the refrigeration system 1 shown in Figure 9, an inlet side water spraying device 33 is provided which is configured to spray water onto the inlet side inner pipe 51 described above from above.

[0063] The inlet-side water spraying device 33 has a nozzle 331 for spraying water, and the nozzle 331 sprays water supplied by a pump (not shown) or the like toward the inlet-side inner pipe 51 located below. The nozzle 331 is configured to spray water onto the portion of the inlet-side inner pipe 51 including the suction port 53. The water sprayed by the inlet-side water spraying device 33 may be at room temperature (0°C to 40°C) or it may be hot water exceeding room temperature.

[0064] Figure 12 is a schematic view from above of the nozzle 331, inlet inner pipe 51, and inlet drain receiving section 17 of the inlet side water spraying device 33 shown in Figure 11. The area where the water sprayed by the inlet side water spraying device 33 is diffused (water diffusion area WA2) is located inside the outer edge 172 of the inlet side recess 171 at the height of the upper end (outer edge 172) of the inlet side recess 171, as shown in Figure 11. In this case, the water sprayed by the outlet side water spraying device 31 is received in the inlet side recess 171.

[0065] In this embodiment, the refrigeration system 1 can melt frost adhering to the inlet inner pipe 51 and the inlet drain receiving section 17 by spraying water from above onto the inlet inner pipe 51 using the inlet water spraying device 33. Note that the refrigeration system 1 shown in Figure 11 can be modified versions of the refrigeration system 1 shown in Figures 2 to 8.

[0066] (Inlet side heating heater) Figure 13 is a schematic diagram showing a modified example of the refrigeration system 1 according to the second embodiment of the present disclosure. As shown in Figure 13, some embodiments of the refrigeration system 1 include, in addition to the configuration of the refrigeration system 1 shown in Figure 9, an inlet side heating heater 34 configured to heat the inlet side drain receiving section 17 described above.

[0067] Examples of inlet-side heating heaters 34 include resistance heaters and induction heaters. In the embodiment shown in Figure 13, the inlet-side heating heater 34 has a resistor 341, such as a metal wire, that generates heat when energized. The resistor 341 may be housed in a space formed inside the inlet-side drain receiving section 17 (see Figure 12), or it may be attached to the outer surface of the inlet-side drain receiving section 17. The inlet-side heating heater 34 generates heat in the resistor 341 by current supplied to the resistor 341 from a power source (not shown), and the generated heat heats the inlet-side drain receiving section 17 by radiation, convection, and conduction.

[0068] As shown in Figure 13, the inlet-side heating heater 34 may further include a resistor 342, such as a metal wire, attached to the outer surface of the inlet-side inner tube 51, which generates heat when energized. The inlet-side heating heater 34 may generate heat in the resistor 342 by current supplied to the resistor 342 from a power source (not shown), and then heat the inlet-side inner tube 51 by radiation, convection, or conduction of the generated heat.

[0069] In this embodiment, the refrigeration system 1 can melt frost adhering to the inlet-side drain receiving section 17 by heating the inlet-side heating heater 34. Note that the refrigeration system 1 shown in Figure 13 can be modified versions of the refrigeration system 1 shown in Figures 2 to 8.

[0070] (Direction of the suction port) Figure 14 is a schematic diagram showing a modified example of a refrigeration system 1 according to one embodiment of the present disclosure. In some embodiments of the refrigeration system 1, the inlet side inner pipe 51 described above is configured such that the suction port 53 is directed upward, as shown in Figure 14.

[0071] In the inlet-side inner pipe 51, the central axis of the suction port 53 is inclined with respect to the horizontal direction. In the illustrated embodiment, the central axis of the suction port 53 extends along the vertical direction in the inlet-side inner pipe 51. In the warm air line-side inner pipe 111, the discharge port 113 is located above the suction port 53, and the discharge port 113 is configured to point downward.

[0072] In this embodiment, the refrigeration system 1 can prevent drain from the inlet side inner pipe 51 from flowing out into the refrigerated space 20 through the inlet 53 by orienting the suction port 53 upward. A modified version of the refrigeration system 1 shown in Figure 14 is applicable to the refrigeration system 1 shown in Figures 1 to 13.

[0073] (Inclination of the inlet side inner pipe) Figure 15 is a schematic diagram showing a modified example of a refrigeration system 1 according to one embodiment of the present disclosure. In some embodiments of the refrigeration system 1, the inlet side inner pipe 51 described above is inclined such that at least a portion of it is located upward as it approaches the suction port 53, as shown in Figure 15.

[0074] At least a portion of the inlet-side inner pipe 51 is inclined horizontally such that it gradually becomes higher towards the upstream end where the suction port 53 is formed.

[0075] In this embodiment of the refrigeration system 1, the inlet inner pipe 51 is inclined so that it is positioned upward as it approaches the suction port 53, which makes it easier for the drain in the inlet inner pipe 51 to flow down towards the heat exchanger 8, thereby improving the drain discharge performance of the inlet inner pipe 51. In some other embodiments, the inlet inner pipe 51 may extend along the horizontal direction. Modifications of the refrigeration system 1 shown in Figure 15 are applicable to the refrigeration system 1 shown in Figures 1 to 14.

[0076] Figure 16 is a schematic diagram showing a refrigeration system 1 according to one embodiment of the present disclosure. Figure 17 is an explanatory diagram for illustrating the suction port filter 531 shown in Figure 16. Figure 18 is an explanatory diagram for illustrating the compressor filter 533 shown in Figure 16. In some embodiments of the refrigeration system 1 described above, as shown in Figures 16 and 17, a suction port filter 531 is provided at the suction port 53 and has an opening smaller than the size of the suction port 53. In one embodiment, the opening MS1 of the suction port filter 531 is 0.5 mm or more and 1.5 mm or less.

[0077] In this embodiment, the refrigeration system 1 is provided with an intake filter 531 at the intake port 53, which allows frost to form on the intake filter 531. In this case, the refrigeration system 1 can prevent frost from entering the inside of the inlet-side inner pipe 51 by the intake filter 531, thereby extending the period during which the refrigerator 3 can operate normally without defrosting.

[0078] A heating element 532 may be provided on the intake filter 531. In this case, the refrigeration system 1 can melt the frost adhering to the intake filter 531 using the heating element 532.

[0079] In some embodiments of the refrigeration system 1 described above, as shown in Figures 16 to 18, the system includes the aforementioned intake filter 531 and a compressor filter 533 provided downstream of the heat exchanger 8 in the inlet line 5, and having a smaller mesh opening than the intake filter 531. In one embodiment, the mesh opening MS2 of the compressor filter 533 is 100 μm or less.

[0080] In this embodiment, the refrigeration system 1, with its compressor filter 533, can suppress the mixing of non-gas phase substances into the circulating gas introduced to the compressor 41.

[0081] Figure 19 is a schematic diagram showing a refrigeration system 1 according to one embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figure 19, an inlet temperature sensor 101 configured to measure the temperature of circulating gas flowing upstream of the heat exchanger 8 in the inlet line 5, or an outlet temperature sensor 102 configured to measure the temperature of circulating gas flowing in the outlet line 7 is provided. The refrigerator 3 described above includes the electric motor 44 described above and the rotational speed control device 45 described above.

[0082] The rotation speed control device 45 is configured to increase the rotation speed of the electric motor 44 within a range below the rated rotation speed when the measured values ​​of the temperature sensors 101 and 102 are below a predetermined temperature during defrosting operation to melt frost attached to the refrigerator 3.

[0083] The rotation speed control device 45 may be configured to increase the rotation speed of the electric motor 44 within a range below the rated rotation speed if the measurement value of the inlet side temperature sensor 101 is below a predetermined temperature (first predetermined temperature). The rotation speed control device 45 may be configured to increase the rotation speed of the electric motor 44 within a range below the rated rotation speed if the measurement value of the outlet side temperature sensor 102 is below a predetermined temperature (second predetermined temperature). The rotation speed control device 45 may be configured to increase the rotation speed of the electric motor 44 within a range below the rated rotation speed if the measurement value of the inlet side temperature sensor 101 is below a predetermined temperature (first predetermined temperature) AND the measurement value of the outlet side temperature sensor 102 is below a predetermined temperature (second predetermined temperature).

[0084] In this embodiment, the refrigeration system 1, when the chiller 3 is in defrost mode, can prompt the chiller 3 to enter the defrost state by increasing the rotation speed of the electric motor 44 using the rotation speed control device 45 if the measured values ​​of the temperature sensors 101 and 102 are below a predetermined temperature, assuming that the chiller 3 is not in the defrost state. The refrigeration system 1 can automatically check whether the chiller 3 is in the defrost state and control the rotation speed if the chiller 3 is not in the defrost state, thus achieving highly reliable defrost operation without the need for visual inspection or manual operation that can lead to human error.

[0085] Figure 20 is a schematic diagram showing a refrigeration system 1 according to one embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figure 20, the at least one refrigerator 3 described above includes a plurality of refrigerators 3 configured to cool circulating gas drawn in from the same refrigeration space 20.

[0086] In the refrigeration system 1, among a plurality of refrigerators 3, those refrigerators 3 that are subject to defrosting operation to melt frost accumulated on them are designated as target refrigerators, and those refrigerators 3 that are not subject to defrosting operation are designated as non-target refrigerators. If there are no non-target refrigerators, the system is configured to ensure that at least one of the target refrigerators performs normal operation.

[0087] In the embodiment shown in Figure 20, the refrigeration system 1 includes an operation control device 103 configured to control the operation of each of the multiple refrigerators 3. The operation control device 103 (controller) is an electronic control unit for controlling the operation of each of the multiple refrigerators 3. The operation control device 103 may be configured as a microcomputer including an input device (input interface), an output device (output interface), a storage device (such as ROM or RAM memory, or an external storage device), and an arithmetic unit (CPU). The operation control device 103 realizes the operation control described later by having the CPU operate (for example, by performing calculations on data) according to instructions of a program loaded into the main memory of the above-mentioned memory.

[0088] The operation control device 103 is capable of acquiring operation mode information indicating whether the current operating mode of each of the multiple chillers 3 is normal operation or defrost operation. Based on the operation mode information, the operation control device 103 identifies whether each of the multiple chillers 3 is a target chiller or a non-target chiller, and adjusts the transition of each of the multiple chillers 3 to defrost operation so that at least one chiller 3 is in normal operation. Alternatively, the operation control device 103 may pre-set a minimum number of chillers 3 that will operate in normal operation, and adjust the transition of each of the multiple chillers 3 to defrost operation so that at least that minimum number of chillers 3 are in normal operation.

[0089] In this embodiment, the refrigeration system 1 can prevent all refrigerators 3 from stopping for defrosting by allowing at least one of the target refrigerators to operate normally when there are no non-target refrigerators. This improves the robustness of cooling the refrigerated space 20 when multiple refrigerators 3 are operated for the same refrigerated space 20.

[0090] In this specification, expressions describing relative or absolute arrangements such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" shall not only describe such arrangements strictly, but also describe states of relative displacement with tolerances or angles or distances sufficient to achieve the same function. For example, expressions describing things being in an equal state such as "identical," "equal," and "homogeneous" shall not only describe states of being strictly equal, but also describe states where tolerances or differences exist to the extent that the same function is achieved. Furthermore, in this specification, expressions describing shapes such as quadrilaterals or cylindrical shapes shall not only describe geometrically precise quadrilaterals or cylindrical shapes, but also describe shapes including concave and concave parts, chamfered parts, etc., to the extent that the same effect is achieved. In addition, in this specification, expressions such as "equipment," "includes," or "possesses" a component are not exclusive expressions that exclude the existence of other components.

[0091] 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.

[0092] The contents described in some of the embodiments above can be understood, for example, as follows:

[0093] [1] A refrigeration system (1) according to at least one embodiment of the present disclosure comprises: a cold storage warehouse (2) having a cold storage space (20) to be cooled inside; and at least one refrigerator (3) configured to cool a circulating gas drawn in from the cold storage space (20), wherein the refrigerator (3) comprises: a compressor (41) configured to compress the circulating gas; a turbine (42) configured to expand the circulating gas; an inlet line (5) for leading the circulating gas from the cold storage space (20) to the compressor (41); a compressed gas line (6) for leading the compressed gas, which is the circulating gas compressed by the compressor (41), to the turbine (42); and an outlet line (7) for leading the circulating gas, which has been expanded by the turbine (42), back into the cold storage space (20). The refrigeration system (1) includes a heat exchanger (8) configured to perform heat exchange between the circulating gas flowing through the inlet line (5) and the compressed gas flowing through the compressed gas line (6), wherein the inlet line (5) includes an inlet-side inner pipe (51) provided in the refrigeration space (20) and having a suction port (53) for drawing the circulating gas from the refrigeration space (20), the outlet line (7) includes an outlet-side inner pipe (71) provided in the refrigeration space (20) and having a blow outlet (73) for guiding the circulating gas into the refrigeration space, and further comprises a warm air line (11) for extracting the compressed gas flowing upstream of the heat exchanger (8) in the compressed gas line (6) and guiding it into the refrigeration space (20), and a warm air flow rate adjustment device (12) configured to adjust the flow rate of the compressed gas flowing through the warm air line (11), The warm air line (11) includes a warm air line side inner pipe (111) provided in the refrigeration space (20) and having a discharge port (113) for discharging the circulating gas toward the intake port (53).

[0094] According to the configuration described in [1] above, the refrigeration system (1) discharges warm air (relatively high temperature and high pressure compressed gas) flowing through the warm air line (11) from the discharge port (113) toward the intake port (53), thereby drawing warm air into the inlet inner pipe (51) via the intake port (53). The refrigeration system (1) can melt frost attached to the chiller (3), particularly the inlet line (5) including the inlet inner pipe (51) and the outlet line (7) including the outlet inner pipe (71), with the warm air drawn in via the intake port (53). According to the configuration described in [1] above, when the refrigeration system (1) melts frost attached to the chiller (3), it can also melt frost attached to the inlet inner pipe (51) and the outlet inner pipe (71) located inside the cold storage warehouse (2), thereby improving the maintainability of defrosting the chiller (3).

[0095] [2] In some embodiments, the refrigeration system (1) described in [1] above, wherein the outlet line (7) includes an outlet inner pipe (71) provided in the refrigeration space (20) and having an outlet (73) for introducing the circulating gas into the refrigeration space (20), the refrigeration system (1) includes an outlet drain receiving section (15) provided in the refrigeration space (20) and positioned below the outlet inner pipe (71) to receive the drain flowing down from the outlet inner pipe (71), and an outlet drain line (16) for introducing the drain from the outlet drain receiving section (15) to the outside of the refrigerated warehouse (2).

[0096] According to the configuration described in [2] above, the refrigeration system (1) can guide the drain generated by melting frost attached to the inlet inner pipe (51) and outlet inner pipe (71), which are located inside the refrigerator (3), particularly the cold storage warehouse (2), into the cold storage space (20) via the outlet inner pipe (71). The refrigeration system (1) can discharge the drain that has been guided into the cold storage space (20) via the outlet inner pipe (71) to the outside of the cold storage warehouse (2) using the outlet drain receiving section (15) and the outlet drain line (16). According to the configuration described in [2] above, the refrigeration system (1) does not need to provide a mechanism for recovering drain that causes pressure loss in the flow path of the circulating gas in the refrigerator (3), thus suppressing the pressure loss of the refrigerator (3).

[0097] [3] In some embodiments, the refrigeration system (1) described in [2] above is further comprising an outlet water spraying device (31) configured to spray water onto the outlet drain receiving section (17) from above.

[0098] According to the configuration described in [3] above, the refrigeration system (1) can melt frost adhering to the outlet drain receiving section (17) by spraying water from above onto the outlet drain receiving section (17) using the outlet water spraying device (31).

[0099] [4] In some embodiments, the refrigeration system (1) described in [2] above is further comprising an outlet heating heater (32) configured to heat the outlet drain receiving section (17).

[0100] According to the configuration described in [4] above, the refrigeration system (1) can melt the frost adhering to the outlet drain receiving section (17) by heating the outlet drain receiving section (17) with the outlet heating heater (32).

[0101] [5] In some embodiments, the refrigeration system (1) described in any of [1] to [4] above, wherein the outlet line (7) includes an outlet-side inner pipe (71) provided in the refrigeration space (20) and having an outlet (73) for introducing the circulating gas into the refrigeration space (20), the outlet-side inner pipe (71) is inclined such that at least a portion of it is located downward toward the outlet (73).

[0102] According to the configuration of [5] above, the refrigeration system (1) is configured such that the outlet inner pipe (71) is tilted downwards as it approaches the outlet (73), which makes it easier for the drain in the outlet inner pipe (71) to flow down toward the outlet (73), thereby improving the drain discharge performance of the outlet inner pipe (71).

[0103] [6] In some embodiments, the refrigeration system (1) described in any of [1] to [5] above further comprises: an inlet-side drain receiving section (17) provided in the refrigeration space (20) and positioned below the inlet-side inner pipe (51) to receive drain flowing down from the inlet-side inner pipe (51); and an inlet-side drain line (18) for guiding the drain from the inlet-side drain receiving section (17) to the outside of the refrigerated warehouse (2).

[0104] According to the configuration described in [6] above, the refrigeration system (1) can receive the drain generated by melting the frost adhering to the inlet inner pipe (51) and flowing down from the inlet inner pipe (51) by the inlet side drain receiving section (17), thereby preventing the drain from falling onto the objects to be frozen placed in the refrigeration space (20). The inlet side drain line (18) allows the drain received by the inlet side drain receiving section (17) to be discharged to the outside of the refrigerated warehouse (2).

[0105] [7] In some embodiments, the refrigeration system (1) described in [6] above is further comprising an inlet water spraying device (33) configured to spray water onto the inlet inner pipe (51) from above.

[0106] According to the configuration described in [7] above, the refrigeration system (1) can melt frost adhering to the inlet inner pipe (51) and the inlet drain receiving section (17) by spraying water from above onto the inlet inner pipe (51) using the inlet water spraying device (33).

[0107] [8] In some embodiments, the refrigeration system (1) described in [6] above is further comprising an inlet heating heater (34) configured to heat the inlet drain receiving section (17).

[0108] According to the configuration described in [8] above, the refrigeration system (1) can melt the frost adhering to the inlet drain receiving section (17) by heating the inlet drain receiving section (17) with the inlet heating heater (34).

[0109] [9] In some embodiments, the refrigeration system (1) described in any of [1] to [8] above is configured such that the inlet inner pipe (51) has an inlet (53) that points upward.

[0110] According to the configuration described in [9] above, the refrigeration system (1) can prevent the drain in the inlet inner pipe (51) from flowing out into the refrigerated space (20) through the suction port (53) by orienting the suction port (53) upward.

[0111]

[10] In some embodiments, the refrigeration system (1) described in any of [1] to [9] above is configured such that the inlet inner pipe (51) is inclined such that at least a portion of it is positioned upward toward the suction port (53).

[0112] According to the configuration of

[10] above, the refrigeration system (1) is configured such that the inlet inner pipe (51) is tilted upward as it approaches the suction port (53), which makes it easier for the drain in the inlet inner pipe (51) to flow down towards the heat exchanger (8), thereby improving the drain discharge performance of the inlet inner pipe (51).

[0113]

[11] In some embodiments, the refrigeration system (1) described in any of [1] to

[10] above, wherein the chiller (3) further includes a cooler (9) configured to perform heat exchange between the compressed gas flowing upstream of the heat exchanger (8) of the compressed gas line (6) and a coolant, and the warm air line (11) has its upstream end connected upstream of the cooler (9) of the compressed gas line (6).

[0114] According to the configuration described in

[11] above, the refrigeration system (1) connects the upstream end of the warm air line (11) upstream of the cooler (9) of the compressed gas line (6). Compared to the case where it is connected between the cooler (9) and the heat exchanger (8) of the compressed gas line (6), high-temperature circulating gas (warm air) can be flowed through the warm air line (11), and defrosting of the chiller (3) by the warm air is promoted.

[0115]

[12] In some embodiments, a refrigeration system (1) according to any one of [1] to

[11] above, wherein the warm air line (11) includes: a first warm air line (13) for drawing the circulating gas from the compressed gas line (6) upstream of the heat exchanger (8) and leading it to the compressed gas line (6) downstream of the heat exchanger (8); and a second warm air line (14A) connected to the compressed gas line (6) downstream of the heat exchanger (8) and having a warm air line side inner pipe (111).

[0116] According to the configuration described in

[12] above, the refrigeration system (1) can change the path of warm air in the chiller (3) by having the warm air line (11) include the first warm air line (13) and the second warm air line (14A), thereby enabling defrost operation on the turbine (42) side of the chiller (3) and defrost operation on the heat exchanger (8) side of the chiller (3).

[0117]

[13] In some embodiments, the refrigeration system (1) described in any of [1] to

[11] above, wherein the warm air line (11) includes: a first warm air line (13) for drawing the circulating gas from the compressed gas line (6) upstream of the heat exchanger (8) and leading it to the compressed gas line (6) downstream of the heat exchanger (8); and a second warm air line (14B) connected to the outlet line (7) and having an inner pipe (111) on the warm air line side.

[0118] According to the configuration described in

[13] above, the refrigeration system (1) can change the path of warm air in the chiller (3) by having the warm air line (11) include the first warm air line (13) and the second warm air line (14B), thereby enabling defrost operation on the turbine (42) side of the chiller (3) and defrost operation on the heat exchanger (8) side of the chiller (3).

[0119]

[14] In some embodiments, the refrigeration system (1) described in any of [1] to

[13] above is provided in the suction port (53) and comprises a suction port filter (531) having an opening smaller than the size of the suction port (53).

[0120] According to the configuration described in

[14] above, the refrigeration system (1) can allow frost to form on the intake filter (531) by providing an intake filter (531) at the intake port (53). In this case, the refrigeration system (1) can prevent frost from entering the inside of the inlet-side inner pipe 51 by the intake filter (531), thereby extending the period during which the refrigerator (3) can operate normally without defrosting.

[0121]

[15] In some embodiments, the refrigeration system (1) described in

[14] above is provided with a heating element (532) in the intake filter (531).

[0122] According to the configuration described in

[15] above, the refrigeration system (1) can melt the frost adhering to the intake filter (531) by the heating element heater (532).

[0123]

[16] In some embodiments, the refrigeration system (1) described in

[14] or

[15] above is further comprising a compressor filter (533) located downstream of the heat exchanger (8) in the inlet line (5) and having a smaller mesh opening than the suction filter (531).

[0124] According to the configuration described in

[16] above, the refrigeration system (1) can suppress the mixing of non-gas phases into the circulating gas led to the compressor (41) by the compressor filter (533).

[0125]

[17] In some embodiments, a refrigeration system (1) according to any of [1] to

[16] above, comprising temperature sensors (101, 102) configured to measure the temperature of the circulating gas flowing through the outlet line (7) or the temperature of the circulating gas flowing upstream of the heat exchanger (8) in the inlet line (5), wherein the refrigerator (3) includes an electric motor (44) configured to generate a rotational force to rotate the compressor (41), and a rotational speed control device (45) for controlling the rotational speed of the electric motor (44), wherein the rotational speed control device (45) is configured to increase the rotational speed of the electric motor (44) within a range below the rated rotational speed when the measurement value of the temperature sensor (101) is below a predetermined temperature during defrost operation to melt frost adhering to the refrigerator (3).

[0126] According to the configuration described in

[17] above, when the refrigerator (3) is in defrost mode, if the temperature sensor (101, 102) readings are below a predetermined temperature, the refrigeration system (1) can assume that the refrigerator (3) is not in defrost mode and increase the rotational speed of the electric motor (44) using the rotational speed control device (45) to encourage the refrigerator (3) to enter defrost mode. The refrigeration system (1) can automatically check whether the refrigerator (3) is in defrost mode and control the rotational speed if the refrigerator (3) is not in defrost mode, thus enabling highly reliable defrost operation without the need for visual inspection or manual operation which can lead to human error.

[0127]

[18] In some embodiments, the refrigeration system (1) described in any of [1] to

[17] above, wherein the at least one refrigerator (3) includes a plurality of refrigerators (3) configured to cool circulating gas drawn in from the same refrigeration space (20), and the refrigeration system (1) is configured such that, among the plurality of refrigerators (3), a refrigerator (3) that is subject to defrosting operation to melt frost attached to the refrigerator (3) is designated as a target refrigerator, and a refrigerator (3) that is not subject to defrosting operation is designated as a non-target refrigerator, and if there are no non-target refrigerators, at least one of the target refrigerators is configured to perform normal operation.

[0128] According to the configuration described in

[18] above, the refrigeration system (1) can prevent all refrigerators (3) from stopping for defrosting by allowing at least one of the target refrigerators to operate normally when there are no non-target refrigerators. This makes it possible to improve the robustness of cooling the refrigerated space (20) when multiple refrigerators (3) are operated for the same refrigerated space (20).

[0129] 1 Refrigeration system 2 Cold storage warehouse 3 Refrigerator 4 Turbomachinery 5 Inlet line 6 Compressed gas line 7 Outlet line 8 Heat exchanger 9 Cooler 11 Warm air line 12 Warm air flow rate adjustment device 13 First warm air line 14 Second warm air line 15 Outlet side drain receiving section 16 Outlet side drain line 17 Inlet side drain receiving section 18 Inlet side drain line 20 Refrigerated space 31 Outlet side water spraying device 32 Outlet side heating heater 33 Inlet side water spraying device 34 Inlet side heating heater 41 Compressor 42 Turbine 43 Rotating shaft 44 Electric motor 51 Inlet side inner pipe 53 Suction port 71 Outlet side inner pipe 73 Outlet 111 Warm air line side inner pipe 113 Discharge port

Claims

1. A refrigeration system comprising: a cold storage warehouse having a cold storage space to be cooled inside; and at least one chiller configured to cool circulating gas drawn in from the cold storage space, wherein the chiller includes: a compressor configured to compress the circulating gas; a turbine configured to expand the circulating gas; an inlet line for leading the circulating gas from the cold storage space to the compressor; a compressed gas line for leading the compressed gas, which is the circulating gas compressed by the compressor, to the turbine; an outlet line for leading the circulating gas, which has been expanded by the turbine, to the cold storage space; and a heat exchanger configured to perform heat exchange between the circulating gas flowing through the inlet line and the compressed gas flowing through the compressed gas line, wherein the inlet line includes an inlet-side inner pipe provided in the cold storage space and having a suction port for drawing in the circulating gas from the cold storage space; and the refrigeration system includes a warm air line for drawing out the compressed gas flowing upstream of the heat exchanger in the compressed gas line and leading it to the cold storage space. A refrigeration system further comprising a warm air flow rate adjustment device configured to adjust the flow rate of the compressed gas flowing through the warm air line, wherein the warm air line includes a warm air line side inner pipe provided in the refrigeration space and having a discharge port for discharging the circulating gas toward the intake port.

2. The refrigeration system according to claim 1, wherein the outlet line includes an outlet-side inner pipe provided in the refrigeration space and having an outlet for introducing the circulating gas into the refrigeration space, and the refrigeration system comprises an outlet-side drain receiving section provided in the refrigeration space and positioned below the outlet-side inner pipe to receive drain flowing down from the outlet-side inner pipe, and an outlet-side drain line for introducing the drain from the outlet-side drain receiving section to the outside of the refrigerated warehouse.

3. The refrigeration system according to claim 2, further comprising an outlet water spraying device configured to spray water from above onto the outlet side drain receiving portion.

4. The refrigeration system according to claim 2, further comprising an outlet heating heater configured to heat the outlet side drain receiving portion.

5. The refrigeration system according to any one of claims 1 to 4, wherein the outlet line includes an outlet-side inner pipe provided in the refrigeration space and having an outlet for introducing the circulating gas into the refrigeration space, and the outlet-side inner pipe is inclined such that at least a portion of it is located downward toward the outlet.

6. The refrigeration system according to any one of claims 1 to 4, comprising: an inlet-side drain receiving section provided in the refrigeration space and positioned below the inlet-side inner pipe to receive drain flowing down from the inlet-side inner pipe; and an inlet-side drain line for guiding the drain from the inlet-side drain receiving section to the outside of the refrigerated warehouse.

7. The refrigeration system according to claim 6, further comprising an inlet water spraying device configured to spray water onto the inlet inner pipe from above.

8. The refrigeration system according to claim 6, further comprising an inlet heating heater configured to heat the inlet side drain receiving section.

9. The refrigeration system according to any one of claims 1 to 4, wherein the inlet inner pipe is configured such that the suction port points upward.

10. The refrigeration system according to any one of claims 1 to 4, wherein at least a portion of the inlet inner pipe is inclined to be positioned upward toward the suction port.

11. The refrigeration system according to any one of claims 1 to 4, further comprising a cooler configured to perform heat exchange between the compressed gas flowing upstream of the heat exchanger in the compressed gas line and a coolant, wherein the warm air line has its upstream end connected upstream of the cooler in the compressed gas line.

12. The refrigeration system according to any one of claims 1 to 4, wherein the warm air line includes a first warm air line for extracting the circulating gas from the compressed gas line upstream of the heat exchanger and guiding it to the compressed gas line downstream of the heat exchanger, and a second warm air line connected to the compressed gas line downstream of the heat exchanger and having an inner pipe on the warm air line side.

13. The refrigeration system according to any one of claims 1 to 4, wherein the warm air line includes a first warm air line for extracting the circulating gas from the compressed gas line upstream of the heat exchanger and guiding it to the compressed gas line downstream of the heat exchanger, and a second warm air line connected to the outlet line and having an inner pipe on the warm air line side.

14. The refrigeration system according to any one of claims 1 to 4, comprising a suction port filter provided at the suction port, having a mesh opening smaller than the size of the suction port.

15. The refrigeration system according to claim 14, wherein the intake filter is provided with a heating element.

16. The refrigeration system according to claim 14, further comprising a compressor filter provided downstream of the heat exchanger in the inlet line and having a smaller mesh opening than the intake filter.

17. A refrigeration system according to any one of claims 1 to 4, comprising a temperature sensor configured to measure the temperature of the circulating gas flowing in the outlet line or the temperature of the circulating gas flowing upstream of the heat exchanger in the inlet line, wherein the chiller includes an electric motor configured to generate a rotational force to rotate the compressor, and a rotational speed control device for controlling the rotational speed of the electric motor, wherein the rotational speed control device is configured to increase the rotational speed of the electric motor within a range below the rated rotational speed when the temperature sensor reading is below a predetermined temperature during defrosting operation to melt frost adhering to the chiller.

18. The refrigeration system according to any one of claims 1 to 4, wherein the at least one refrigerator includes a plurality of refrigerators configured to cool a circulating gas drawn in from the same refrigerated space, and the refrigeration system is configured such that, among the plurality of refrigerators, a refrigerator that is subject to defrosting operation to melt frost attached to the refrigerator is designated as a target refrigerator, and a refrigerator that is not subject to defrosting operation is designated as a non-target refrigerator, and if there are no non-target refrigerators, at least one of the target refrigerators is configured to perform normal operation.

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