Refrigeration system

Abstract

To provide a refrigeration system that can improve the robustness of a refrigeration system equipped with an electric motor. [Solution] A refrigeration system for cooling a heat transfer medium for supplying cooling energy to a cooling target, comprising: a turbomachinery equipped with a turbine, a compressor, and an electric motor; a closed loop including a compressed fluid line for guiding compressed fluid compressed by the compressor to the turbine, and an expanded fluid line for guiding expanded fluid expanded by the turbine to the compressor; a cooler for cooling the compressed fluid flowing through the compressed fluid line; a heat transfer medium cooler for performing heat exchange between the expanded fluid flowing through the expanded fluid line and the heat transfer medium; a regenerative heat exchanger for performing heat exchange between the compressed fluid that has passed through the cooler and the expanded fluid that has passed through the heat transfer medium cooler; and an electric motor cooling line for extracting compressed fluid from between the cooler and the regenerative heat exchanger in the compressed fluid line and supplying it to a casing housing the electric motor.

Description

Technical Field

[0001] The present disclosure relates to a refrigeration system.

Background Art

[0002] Some refrigeration systems for cooling a heat medium for supplying thermal energy to a cooling target include a closed loop in which a fluid (refrigerant) that exchanges heat with the heat medium through an indirect heat exchanger circulates (for example, Patent Document 1). The closed loop may be provided with the indirect heat exchanger, a turbine, a compressor, a water-cooled heat exchanger for cooling the heat medium, and a regenerative heat exchanger for exchanging heat between the fluid circulating in the closed loop. Further, the refrigeration system may include an electric motor for rotating the compressor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] During operation of the refrigeration system, a refrigerant such as cooling water or cooling gas cooled by equipment outside the refrigeration system may be used to cool the electric motor that generates heat. In this case, since the cooling temperature of the electric motor may change depending on the state of the equipment outside the refrigeration system, there is a risk that the cooling of the electric motor becomes unstable. If the cooling of the electric motor is unstable, there is a risk of causing thermal degradation of the electric motor, and thus the robustness of the refrigeration system may be impaired.

[0005] In view of the above circumstances, at least one embodiment of the present disclosure aims to provide a refrigeration system that can improve the robustness of a refrigeration system including an electric motor.

Means for Solving the Problems

[0006] A refrigeration system according to at least one embodiment of this disclosure is A refrigeration system for cooling a heat transfer medium that supplies cold energy to an object to be cooled, A turbomachinery equipped with a turbine, compressor and electric motor, A closed loop including a compressed fluid line for guiding the compressed fluid, which is the fluid compressed by the compressor, to the turbine, and an expanded fluid line for guiding the expanded fluid, which is the fluid expanded by the turbine, to the compressor, A cooler configured to cool the compressed fluid flowing through the compressed fluid line, A heat transfer medium cooler configured to perform heat exchange between the expanding fluid flowing in the expansion fluid line and the heat transfer medium, A regenerative heat exchanger configured to perform heat exchange between the compressed fluid that has passed through the cooler and the expanded fluid that has passed through the heat transfer cooler, The system includes an electric motor cooling line for extracting the compressed fluid from between the cooler and the regenerative heat exchanger of the compressed fluid line and supplying it to a casing that houses the electric motor. [Effects of the Invention]

[0007] According to at least one embodiment of the present disclosure, a refrigeration system is provided that can improve the robustness of a refrigeration system equipped with an electric motor. [Brief explanation of the drawing]

[0008] [Figure 1] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view along the axis of a turbomachinery in a refrigeration system according to one embodiment of the present disclosure. [Figure 3] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 4] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 5] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 6] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 7] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 8] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 9] This figure schematically shows a refrigeration system according to one embodiment of the present disclosure. [Figure 10] Figure 9 is an explanatory diagram illustrating the opening and closing operation of the valve shown. [Modes for carrying out the invention]

[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 one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view of the refrigeration system 1 according to one embodiment of the present disclosure along the axis LA of the turbomachinery 2. Figure 2 shows a cross-section including the axis LA of the rotating shaft 25 of the turbomachinery 2. Some embodiments of the refrigeration system 1 are for cooling a heat transfer medium for supplying cold energy to an object to be cooled. The refrigeration system 1, as shown in Figure 1, comprises a turbomachinery 2, a closed-loop 3, a cooler 4, a heat transfer medium cooler 5, and a regenerative heat exchanger 6.

[0011] As shown in FIGS. 1 and 2, the turbomachine 2 includes a turbine 21 for expanding a fluid for cooling a heat medium, a compressor 22 for compressing the fluid, an electric motor 23 for rotating the compressor 22, and a casing 24 for accommodating at least the electric motor 23. The compressed fluid compressed by the compressor 22 is heated and pressurized to a relatively high temperature and pressure compared to before being introduced into the compressor 22. The expanded fluid expanded by the turbine 21 is cooled and depressurized to a relatively low temperature and pressure compared to before being introduced into the turbine 21.

[0012] The closed loop 3 is a flow path for circulating a fluid for cooling a heat medium. As shown in FIG. 1, the closed loop 3 includes a compressed fluid line 31 and an expanded fluid line 32. The compressed fluid line 31 is a flow path for guiding the compressed fluid, which is the fluid compressed by the compressor 22, from the compressor 22 to the turbine 21. The expanded fluid line 32 is a flow path for guiding the expanded fluid, which is the fluid expanded by the turbine 21, from the turbine 21 to the compressor 22.

[0013] The fluid for cooling the heat medium is preferably a refrigerant that liquefies at a relatively low temperature. Examples of such a refrigerant include any one selected from helium, hydrogen, neon, nitrogen, argon, oxygen, air, hydrocarbons, or a mixture of two or more of them. By using a refrigerant that liquefies at a relatively low temperature (for example, any one selected from helium, hydrogen, neon, nitrogen, argon, oxygen, air, hydrocarbons, or a mixture of two or more of them) as the fluid for cooling the heat medium, the temperature range that the refrigeration system 1 can handle can be expanded to a region including extremely low temperatures and ultra-low temperatures.

[0014] (Rotating shaft) As shown in FIGS. 1 and 2, the turbomachine 2 includes a rotating shaft 25. The rotating shaft 25 extends along the axis LA of the rotating shaft 25. In the illustrated embodiment, on one side in the extending direction of the rotating shaft 25, the above-described turbine (turbine wheel) 21 is attached. On the other side in the extending direction of the rotating shaft 25, the above-described compressor (compressor impeller) 22 is attached. In other words, the turbine 21 and the compressor 22 are coaxially arranged with each other via the rotating shaft 25 which is the output shaft of the electric motor 23, and are respectively connected to the rotating shaft 25. The casing 24 is configured to be able to accommodate the turbine 21, the compressor 22, and the rotating shaft 25.

[0015] Hereinafter, the direction in which the axis LA of the rotating shaft 25 extends is defined as the axial direction of the rotating shaft 25 (turbomachine 2), the direction orthogonal to the axis LA is defined as the radial direction of the rotating shaft 25 (turbomachine 2), and the circumferential direction around the axis LA is defined as the circumferential direction of the rotating shaft 25 (turbomachine 2).

[0016] (Electric motor) The electric motor 23 is provided between the turbine 21 and the compressor 22 and is configured to generate a rotational force for rotating the rotating shaft 25. The electric motor 23 includes a rotor 231 attached to the rotating shaft 25 and a stator 232 disposed with a gap therebetween so as to cover the outer peripheral side of the rotor 231.

[0017] The rotor 231 is provided so as to be rotatable integrally with the rotating shaft 25. Examples of the rotor 231 include a permanent magnet. The stator 232 is supported by the casing 24. Examples of the stator 232 include a stationary coil. The electric motor 23 is adapted to be 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 rotate the rotating shaft 25, the turbine 21, and the compressor 22.

[0018] (Casing) In the illustrated embodiment, as shown in Figure 2, the casing 24 has a turbine housing chamber 11 for rotatably housing the turbine 21, a compressor housing chamber 12 for rotatably housing the compressor 22, and a motor housing chamber 13 for housing the electric motor 23 (rotor 231 and stator 232).

[0019] In the illustrated embodiment, the casing 24 includes an outer wall 14 defining the outer circumferential surface of the motor housing chamber 13, a turbine-side partition wall 15 separating the turbine housing chamber 11 from the motor housing chamber 13, a compressor-side partition wall 16 separating the compressor housing chamber 12 from the motor housing chamber 13, a turbine casing 17 forming the turbine housing chamber 11 between itself and the turbine-side partition wall 15, and a compressor casing 18 forming the compressor housing chamber 12 between itself and the compressor-side partition wall 16. The motor housing chamber 13 is formed by the outer wall 14, the turbine-side partition wall 15, and the compressor-side partition wall 16.

[0020] The turbine-side partition wall 15 may be formed separately from the turbine casing 17 and the outer wall 14, or it may be formed integrally with either the turbine casing 17 or the outer wall 14. Similarly, the compressor-side partition wall 16 may be formed separately from the compressor casing 18 and the outer wall 14, or it may be formed integrally with either the compressor casing 18 or the outer wall 14.

[0021] In the illustrated embodiment, the turbine casing 17 (casing 24) has a turbine-side inlet passage 172 for guiding fluid from a turbine-side inlet 171 formed on the outer surface of the turbine casing 17 to the turbine housing chamber 11, and a turbine-side outlet passage 174 for guiding fluid from the turbine housing chamber 11 to a turbine-side outlet 173 formed on the outer surface of the turbine casing 17. In the embodiment shown in Figure 2, the turbine-side inlet passage 172 includes a turbine scroll passage 172A, which is a spiral-shaped passage provided on the outer circumference of the turbine 21 and extending along the circumferential direction of the rotating shaft 25. The turbine-side outlet passage 174 extends along the axial direction of the rotating shaft 25.

[0022] The fluid introduced from outside the casing 24 (compressed fluid line 31) via the turbine-side inlet 171 flows through the turbine-side inlet passage 172 before being guided to the turbine 21. After passing through the turbine 21, the fluid flows through the turbine-side outlet passage 174 before being discharged to the outside of the casing 24 (expansion fluid line 32) via the turbine-side outlet 173.

[0023] In the illustrated embodiment, the compressor casing 18 (casing 24) has a compressor-side inlet passage 182 for guiding fluid from a compressor-side inlet 181 formed on the outer surface of the compressor casing 18 to the compressor housing chamber 12, and a compressor-side outlet passage 184 for guiding fluid from the compressor housing chamber 12 to a compressor-side outlet 183 formed on the outer surface of the compressor casing 18. In the embodiment shown in Figure 2, the compressor-side outlet passage 184 includes a compressor scroll passage 184A, which is a spiral-shaped passage provided on the outer circumference of the compressor 22 and extending along the circumferential direction of the rotating shaft 25. The compressor-side inlet passage 182 extends along the axial direction of the rotating shaft 25.

[0024] By rotating the compressor 22, fluid is drawn in from outside the casing 24 (expansion fluid line 32) via the compressor-side inlet 181. The drawn-in fluid flows through the compressor-side inlet passage 182 before being guided to the compressor 22. After passing through the compressor 22, the fluid flows through the compressor-side outlet passage 184 before being discharged to the outside of the casing 24 (compression fluid line 31) via the compressor-side outlet 183.

[0025] (turbine) The turbine (turbine wheel) 21 is configured to guide fluid, which is drawn from the outside in the radial direction of the rotating shaft 25, in a first axial direction along the axial direction of the rotating shaft 25. The turbine 21 is mounted so as to be rotatable integrally with the rotating shaft 25 about the axis LA of the rotating shaft 25. The turbine 21 rotates due to the fluid guided into it, thereby assisting the rotation of the compressor 22.

[0026] In the illustrated embodiment, the turbine 21 includes a substantially frustoconical hub 211 having a hub surface 212 oriented toward a first direction, as shown in Figure 2, and a plurality of turbine blades 213 rising from the hub surface 212. The hub surface 212 is formed in a concave curve, with the distance from the axis LA decreasing as it moves toward the first direction. Each of the plurality of turbine blades 213 is spaced apart from the other turbine blades 213 in the circumferential direction of the rotating shaft 25.

[0027] (Compressor) The compressor (compressor impeller) 22 is configured to guide fluid, which is guided in a first direction along the axial direction of the rotating shaft 25, to the radially outer side of the rotating shaft 25. The compressor 22 is mounted to rotate integrally with the rotating shaft 25 about the axis LA of the rotating shaft 25. The compressor 22 rotates by the turbine 21 and the electric motor 23, thereby drawing fluid into the casing 24 and compressing the fluid guided to the compressor 22.

[0028] In the illustrated embodiment, the compressor 22 includes a substantially frustoconical hub 221 having a hub surface 222 oriented toward a second direction, as shown in Figure 2, and a plurality of compressor blades 223 rising from the hub surface 222. The hub surface 222 is formed in a concave curve, with the distance from the axis LA decreasing as it moves toward the second direction. Each of the plurality of compressor blades 223 is spaced apart from the other compressor blades 223 in the circumferential direction of the rotating shaft 25.

[0029] The compressed fluid line 31 has its upstream end connected to the compressor-side discharge port 183 and its downstream end connected to the turbine-side inlet 171. The compressed fluid compressed by the compressor 22 is guided to the turbine 21 through the compressed fluid line 31.

[0030] The expansion fluid line 32 has its upstream end connected to the turbine-side discharge port 173 and its downstream end connected to the compressor-side inlet 181. The expansion fluid expanded by the turbine 21 is guided to the compressor 22 through the expansion fluid line 32.

[0031] (cooler) The cooler 4 is configured to cool the compressed fluid flowing through the compressed fluid line 31. In the illustrated embodiment, the cooler 4 includes at least a heat exchange section 41 configured to exchange heat between the compressed fluid flowing through the compressed fluid line 31 and a coolant (e.g., a cooling liquid such as water) that is cooler than the compressed fluid. The compressed fluid flowing through the compressed fluid line 31 is cooled by heat transfer in the cooler 4. The compressed fluid cooled by the cooler 4 is introduced into the regenerative heat exchanger 6 through the compressed fluid line 31.

[0032] In the illustrated embodiment, the cooler 4 includes a refrigerant circulation line 42 for circulating refrigerant and a cooling device 43 for cooling the refrigerant flowing through the refrigerant circulation line 42. The refrigerant circulation line 42 is a flow path for returning refrigerant taken from the heat exchange unit 41 to the heat exchange unit 41. The refrigerant circulation line 42 is provided with a refrigerant pump 44 for supplying refrigerant in the refrigerant circulation line 42 and a radiator 45. The cooling device 43 includes a radiator 45 and a fan 46 for air-cooling the radiator 45.

[0033] The refrigerant, which has been heated by heat exchange with the compressed fluid flowing through the compressed fluid line 31 in the heat exchange section 41, is guided to the refrigerant circulation line 42 by the refrigerant pump 44, cooled by the cooling device 43 including the radiator 45, and then guided back to the heat exchange section 41.

[0034] The refrigerant circulating in the refrigerant circulation line 42 is not limited to liquid form and may be gaseous. The refrigerant circulating in the refrigerant circulation line 42 may be a fluorine-based refrigerant (refrigerant gas) such as R-1234ZE, or an antifreeze such as glycol water. It is preferable that the refrigerant circulating in the refrigerant circulation line 42 has a lower freezing point than water.

[0035] (heat medium cooler) The heat transfer medium cooler 5 is configured to perform heat exchange between the expanding fluid flowing through the expansion fluid line 32 and the heat transfer medium. Heat transfer in the heat transfer medium cooler 5 heats the expanding fluid and cools the heat transfer medium. The heat transfer medium cooled by the heat transfer medium cooler 5 is then led to the heat transfer medium supply destination. At the heat transfer medium supply destination, cold energy is transferred from the heat transfer medium to the object to be cooled, thereby cooling the object.

[0036] (Regenerative heat exchanger) The regenerative heat exchanger 6 is configured to exchange heat between the compressed fluid that has passed through the cooler 4 and the expanded fluid that has passed through the heat transfer medium cooler 5. Through heat transfer in the regenerative heat exchanger 6, the compressed fluid is cooled and the expanded fluid is heated. The compressed fluid cooled by the cooler 4 and the regenerative heat exchanger 6 is introduced into the turbine 21. The expanded fluid heated by the heat transfer medium cooler 5 and the regenerative heat exchanger 6 is introduced into the compressor 22.

[0037] The cooler 4, the heat transfer medium cooler 5, and the regenerative heat exchanger 6 are configured to transfer heat between two fluids at different temperatures separated by a heat transfer wall. The refrigeration system 1 is configured to allow fluid to circulate within a closed circuit 10, which consists of the turbomachinery 2, the closed loop 3, the cooler 4, the heat transfer medium cooler 5, and the regenerative heat exchanger 6. By forming a closed circuit 10 with the components of the refrigeration system 1, leakage of fluid to the outside of the refrigeration system 1 can be suppressed.

[0038] (Electric motor cooling line) In some embodiments of the refrigeration system 1, as shown in Figure 1, an electric motor cooling line 7 is provided. The electric motor cooling line 7 is a passage for extracting compressed fluid from between the cooler 4 and the regenerative heat exchanger 6 of the compressed fluid line 31 and supplying it to the casing 24 that houses the electric motor 23. The compressed fluid line 31, the expansion fluid line 32, and the electric motor cooling line 7 may be formed by piping, and the piping may be composed of multiple sections connected via flanges or the like.

[0039] Inside the casing 24, a motor-side inlet passage 242 is formed to guide fluid from a motor-side inlet 241 formed on the outer surface of the casing 24 to the motor housing chamber 13. The electric motor cooling line 7 has its upstream end 71 connected between the cooler 4 and the regenerative heat exchanger 6 of the compressed fluid line 31, and its downstream end 72 connected to the motor-side inlet 241. The compressed fluid supplied to the casing 24 through the electric motor cooling line 7 is guided to the motor housing chamber 13 through the motor-side inlet passage 242, and in the motor housing chamber 13, it cools the electric motor 23.

[0040] In this embodiment, the refrigeration system 1 uses the compressed fluid flowing between the cooler 4 and the regenerative heat exchanger 6 of the compressed fluid line 31 to cool the electric motor 23, enabling stable cooling of the electric motor 23 regardless of the operating state of the turbomachinery 2. This improves the robustness of the refrigeration system 1. If a fluid cooled by an external device of the refrigeration system 1 were used to cool the electric motor 23, the cooling temperature of the electric motor 23 might change depending on the state of the device, potentially leading to unstable cooling of the electric motor 23. Furthermore, the compressed fluid flowing between the cooler 4 and the regenerative heat exchanger 6 of the compressed fluid line 31 is at a temperature more suitable for use as a refrigerant for cooling the electric motor 23 compared to the compressed fluid flowing upstream of the cooler 4 of the compressed fluid line 31, or the compressed fluid flowing downstream of the regenerative heat exchanger 6 of the compressed fluid line 31.

[0041] In some embodiments of the refrigeration system 1, as shown in Figure 1, a return line 8 is provided to return the compressed fluid supplied to the casing 24 by the electric motor cooling line 7 back from the casing 24 to the downstream side of the heat transfer medium cooler 5 in the expansion fluid line 32. The return line 8 may be formed by piping, and the piping may consist of multiple sections connected via flanges or the like.

[0042] In the illustrated embodiment, the downstream end 82 of the return line 8 is connected downstream of the regenerative heat exchanger 6 of the expansion fluid line 32. If the downstream end 82 of the return line 8 were connected upstream of the regenerative heat exchanger 6 of the expansion fluid line 32, the temperature difference between the two fluids exchanging heat in the regenerative heat exchanger 6 would be smaller due to the fluid introduced to the regenerative heat exchanger 6 through the return line 8, compared to when it is connected downstream of the regenerative heat exchanger 6 of the expansion fluid line 32, which could lead to a decrease in the refrigeration performance of the refrigeration system 1. By connecting the downstream end 82 of the return line 8 downstream of the regenerative heat exchanger 6 of the expansion fluid line 32, it is possible to suppress the reduction in the temperature difference between the two fluids exchanging heat in the regenerative heat exchanger 6 due to the fluid introduced to the expansion fluid line 32 through the return line 8.

[0043] Inside the casing 24, a motor-side outlet channel 244 is formed to guide fluid from the motor housing chamber 13 to a motor-side outlet 243 formed on the outer surface of the casing 24. The return line 8 has its upstream end 81 connected to the motor-side outlet 243 and its downstream end 82 connected downstream of the heat transfer medium cooler 5 of the expansion fluid line 32. Due to the pressure difference between the upstream end 71 of the electric motor cooling line 7 and the downstream end 82 of the return line 8, a portion of the fluid flowing through the closed loop 3 is drawn out of the closed loop 3 into the electric motor cooling line 7, and flows from the upstream end 71 of the electric motor cooling line 7 towards the downstream end 82 of the return line 8.

[0044] In this embodiment, the refrigeration system 1 can return the fluid used to cool the electric motor 23 to the closed loop 3 via the return line 8. By making the electric motor cooling line 7, the return line 8, and the casing 24 part of the closed circuit 10 that the refrigeration system 1 is configured as, the leakage of fluid to the outside of the refrigeration system 1 can be suppressed, thereby improving the robustness of the refrigeration system 1.

[0045] The fact that the casing 24 constitutes part of the closed circuit 10 means that the fluid supply and discharge systems (motor housing chamber 13, motor-side inlet passage 242, and motor-side outlet passage 244) used to cool the electric motor 23, which are formed inside the casing 24, do not communicate with the space outside the casing 24 or with the outside of the closed circuit 10. However, since the fluid supply and discharge systems for the turbine 21 (turbine housing chamber 11, turbine-side inlet passage 172, and turbine-side outlet passage 174) and the compressor 22 (compressor housing chamber 12, compressor-side inlet passage 182, and compressor-side outlet passage 184), which are formed inside the casing 24, constitute part of the closed circuit 10, the fluid supply and discharge systems used to cool the electric motor 23 may communicate with each other.

[0046] (Turbine-side bearing, compressor-side bearing) In some embodiments, the turbomachinery 2 includes, as shown in Figure 2, at least one turbine-side bearing 26 configured to rotatably support a rotating shaft 25 between a turbine 21 and an electric motor 23, and at least one compressor-side bearing 27 configured to rotatably support a rotating shaft 25 between a compressor 22 and an electric motor 23.

[0047] In the embodiment shown in Figure 2, the at least one turbine-side bearing 26 includes a radial bearing 26A configured to receive the radial load of the rotating shaft 25 and a thrust bearing 28 configured to receive the thrust load of the rotating shaft 25. The at least one compressor-side bearing 27 includes a radial bearing 27A configured to receive the radial load of the rotating shaft 25. In other embodiments, the compressor-side bearing 27 may include a radial bearing 27A and a thrust bearing 28, and the turbine-side bearing 26 may include a radial bearing 26A.

[0048] Each of the turbine-side bearings 26 and compressor-side bearings 27 is supported by the casing 24. The rotor 231 is mounted on the rotating shaft 25 between the turbine-side bearing 26 closest to the compressor 22 and the compressor-side bearing 27 closest to the turbine 21. The rotating shaft 25 is supported by the turbine-side bearings 26 and compressor-side bearings 27, allowing it to rotate about its axis LA.

[0049] Inside the casing 24, there is a turbine-side communication hole 151 that connects the turbine housing chamber 11 and the motor housing chamber 13, and a compressor-side communication hole 161 that connects the compressor housing chamber 12 and the motor housing chamber 13. The turbine-side communication hole 151 and the compressor-side communication hole 161 extend along the direction in which the rotating shaft 25 extends, and the rotating shaft 25 is inserted through them.

[0050] The turbine-side partition wall 15 and the compressor-side partition wall 16 are formed in an annular shape extending along the circumferential direction of the rotating shaft 25. The turbine-side communication hole 151 is formed by the inner circumferential surface of the turbine-side partition wall 15. The compressor-side communication hole 161 is formed by the inner circumferential surface of the compressor-side partition wall 16.

[0051] The turbine-side bearing 26 described above is installed in the turbine-side communication hole 151. The compressor-side bearing 27 described above is installed in the compressor-side communication hole 161. In the embodiment shown in Figure 2, the turbine-side communication hole 151 includes a thrust bearing housing chamber 151A for housing the thrust bearing 28. If the compressor-side bearing 27 includes the thrust bearing 28, the compressor-side communication hole 161 may also include the thrust bearing housing chamber 151A.

[0052] The motor-side inlet passage 242 and the motor-side outlet passage 244 may be directly connected to the motor housing chamber 13, or they may be connected to either the turbine-side communication hole 151 or the compressor-side communication hole 161 and connected to the motor housing chamber 13 via the turbine-side communication hole 151 or the compressor-side communication hole 161.

[0053] In the embodiment shown in Figure 2, the motor-side inlet passage 242 is connected to the turbine-side communication hole 151 or the compressor-side communication hole 161, specifically the communication hole on the side that does not include the thrust bearing housing chamber 151A (in the illustrated example, the compressor-side communication hole 161), at a position further away from the motor housing chamber 13 than all of the compressor-side bearings 27 (bearings). The motor-side outlet passage 244 is connected to the motor housing chamber 13. The motor-side outlet passage 244 also communicates with the thrust bearing housing chamber 151A. In this case, the turbine-side bearing 26 and the compressor-side bearing 27 are cooled by fluid introduced to the turbine-side communication hole 151 and the compressor-side communication hole 161 through the electric motor cooling line 7 and the motor-side inlet passage 242.

[0054] In the embodiment shown in Figure 2, a bearing-side inlet passage 102 is formed inside the casing 24. One end of the passage is connected to a bearing-side inlet 101 formed on the outer surface of the casing 24, and the other end is connected to the turbine-side communication hole 151 or the compressor-side communication hole 161, specifically the communication hole on the side containing the thrust bearing housing chamber 151A (in the illustrated example, the turbine-side communication hole 151), at a position further away from the motor housing chamber 13 than all the turbine-side bearings 26, including the thrust bearing 28. The refrigeration system 1 includes a bearing cooling line 103 that branches off from the electric motor cooling line 7 and is connected to the bearing-side inlet 101.

[0055] The thrust bearing 28 is cooled by fluid introduced into the thrust bearing housing chamber 151A through the bearing cooling line 103 and the bearing-side inlet passage 102. The fluid that has cooled the thrust bearing 28 is returned to the closed loop 3 through the motor-side outlet passage 244 and the return line 8.

[0056] In some embodiments of the refrigeration system 1, the turbomachinery 2 described above uses gas bearings for the bearings (radial bearing 26A, radial bearing 27A, thrust bearing 28) that rotatably support the rotating shaft 25. By using gas bearings as the bearings (radial bearing 26A, radial bearing 27A, thrust bearing 28) of the turbomachinery 2, oil-free operation can be achieved. This avoids the problem of reduced oil fluidity at low temperatures, thereby improving the reliability of the refrigeration system 1 at low temperatures. Furthermore, since the refrigeration system 1 does not require a mechanism or structure for supplying oil to the bearings (radial bearing 26A, radial bearing 27A, thrust bearing 28), the turbomachinery 2 can be miniaturized, and consequently, the refrigeration system 1 can be miniaturized.

[0057] (Fluid replenishment line) Figures 3 to 7 are schematic diagrams showing a refrigeration system 1 according to one embodiment of the present disclosure. In some embodiments of the refrigeration system 1, as shown in Figures 3 to 7, a fluid replenishment line 9 is provided for replenishing the fluid flowing through the closed loop 3. The fluid replenishment line 9 has its upstream end connected to a fluid supply source and its downstream end connected to the closed circuit 10 that constitutes the refrigeration system 1. In the illustrated embodiments, the fluid supply source is a fluid storage device (storage tank) 91 provided by the refrigeration system 1 and configured to store fluid. The refrigeration system 1 may also include an on-off valve 92 for opening and closing the fluid replenishment line 9. The on-off valve 92 may be a manual on-off valve that can be switched on and off manually. By opening and closing the on-off valve 92, fluid can be intermittently supplied to the closed circuit 10 through the fluid replenishment line 9.

[0058] The refrigeration system 1 is equipped with a fluid replenishment line 9, which allows the fluid in the closed circuit 10 to be refilled without having to open the closed circuit 10, such as by dismantling the piping, if the fluid level in the closed circuit 10 decreases during maintenance or in the event of a malfunction. This improves the operational reliability of the refrigeration system 1.

[0059] The downstream end of the fluid replenishment line 9 is preferably connected to a location where the fluid temperature is 0°C or higher during operation of the refrigeration system 1, and more preferably to a location where the temperature is ambient (0°C to 40°C). If the downstream end of the fluid replenishment line 9 is connected to a location where the fluid temperature is below 0°C during operation of the refrigeration system 1, there is a risk that the amount of heat radiated to the outside of the refrigeration system 1 will increase by the amount of the fluid replenishment line 9. On the other hand, if the downstream end of the fluid replenishment line 9 is connected to a location where the fluid temperature is 0°C or higher during operation of the refrigeration system 1, the amount of heat radiated to the outside of the refrigeration system 1 can be suppressed. Furthermore, if the downstream end of the fluid replenishment line 9 is connected to a location where the fluid temperature is ambient during operation of the refrigeration system 1, heat input from the outside of the refrigeration system 1 and heat dissipation to the outside of the refrigeration system 1 can be suppressed, the refrigeration performance of the refrigeration system 1 can be maintained, and the reliability of the refrigeration system 1 can be improved.

[0060] Locations where the fluid temperature exceeds 0°C during operation of the refrigeration system 1 include the downstream side of the regenerative heat exchanger 6 in the expansion fluid line 32, the upstream side of the regenerative heat exchanger 6 in the compression fluid line 31, the electric motor cooling line 7, the return line 8, the motor housing chamber 13, the motor-side inlet passage 242, and the motor-side outlet passage 244.

[0061] During operation of the refrigeration system 1, the fluid temperature becomes ambient temperature in the following locations: downstream of the regenerative heat exchanger 6 in the expansion fluid line 32, the return line 8, the motor housing chamber 13, and the motor-side outlet passage 244.

[0062] In the embodiment shown in Figure 3, the downstream end of the fluid replenishment line 9(9A) is connected to the electric motor cooling line 7. In the embodiment shown in Figure 4, the downstream end of the fluid replenishment line 9(9B) is connected to the return line 8. In the embodiment shown in Figure 5, the downstream end of the fluid replenishment line 9(9C) is connected to the motor housing chamber 13. In some other embodiments, the downstream end of the fluid replenishment line 9 may be connected to the motor-side inlet passage 242 or the motor-side outlet passage 244.

[0063] In the embodiment shown in Figure 6, the downstream end of the fluid replenishment line 9(9D) is connected upstream of the regenerative heat exchanger 6 of the compressed fluid line 31. The downstream end of the fluid replenishment line 9(9D) may be connected between the cooler 4 and the regenerative heat exchanger 6 of the compressed fluid line 31, as shown in the illustrated example, or it may be connected upstream of the cooler 4 of the compressed fluid line 31. In the embodiment shown in Figure 7, the downstream end of the fluid replenishment line 9(9E) is connected downstream of the regenerative heat exchanger 6 of the expansion fluid line 32.

[0064] The lines constituting the closed circuit 10 described above can be divided into high-pressure lines where the fluid pressure is relatively high during the operation of the refrigeration system 1, and low-pressure lines where the fluid pressure is relatively low during the operation of the refrigeration system 1. Examples of high-pressure lines include the compressed fluid line 31, the electric motor cooling line 7, and the motor-side inlet passage 242. Examples of low-pressure lines include the expanded fluid line 32, the return line 8, the motor housing chamber 13, and the motor-side outlet passage 244.

[0065] The downstream end of the fluid replenishment line 9 is preferably connected to a low-pressure line where the fluid pressure is relatively low during the operation of the refrigeration system 1. If the downstream end of the fluid replenishment line 9 is connected to a high-pressure line, there is a high possibility that fluid will flow back from the high-pressure line to the fluid replenishment line 9. In contrast, if the downstream end of the fluid replenishment line 9 is connected to a low-pressure line, there is a low possibility that fluid will flow back from the low-pressure line to the fluid replenishment line 9, thus improving the reliability of fluid replenishment via the fluid replenishment line 9 during the operation of the refrigeration system 1.

[0066] In some embodiments of the refrigeration system 1, the fluid flowing through the closed loop 3 is pressurized to a state higher than atmospheric pressure by the fluid replenished via the fluid replenishment line 9 described above. In one embodiment, the fluid stored in the fluid storage device 91 described above is kept at a relatively high pressure so that the fluid flowing through the closed loop 3 is pressurized when the fluid is replenished via the fluid replenishment line 9. In another embodiment, a compressor for pressurizing the fluid is provided in the fluid replenishment line 9 described above, and the fluid flowing through the fluid replenishment line 9 is pressurized by the compressor so that the fluid flowing through the closed loop 3 is pressurized when the fluid is replenished via the fluid replenishment line 9.

[0067] In the refrigeration system 1 according to this embodiment, the refrigeration capacity of the refrigeration system 1 can be improved by pressurizing the closed circuit 10, such as the closed loop 3, which is composed of the refrigeration system 1, with the fluid replenished via the fluid replenishment line 9, thereby enabling the refrigeration system 1 to be made smaller and have a larger capacity.

[0068] (Anomaly notification device) Figure 8 is a schematic diagram showing a refrigeration system 1 according to one embodiment of the present disclosure. As shown in Figure 8, a refrigeration system 1 according to several embodiments includes a pressure acquisition device (pressure sensor) 202 configured to acquire the pressure of the fluid flowing through the low-pressure line described above (any of the expansion fluid line 32, return line 8 (illustrated example), motor housing chamber 13, or motor-side outlet passage 244), and an abnormality notification device 203 configured to notify of an abnormality when the fluid pressure acquired by the pressure acquisition device 202 falls below a predetermined pressure.

[0069] In the embodiment shown in Figure 8, the refrigeration system 1 includes a notification control device (controller) 204 configured to control the notification operation of the abnormal notification device 203 according to the fluid pressure acquired by the pressure acquisition device 202.

[0070] The notification control device 204 is an electronic control unit for controlling the notification operation of the abnormal notification device 203. The notification control device 204 may be composed of analog circuits that can be manufactured relatively inexpensively, or it may be composed of a microcomputer consisting of a CPU (processor) (not shown), memory such as ROM or RAM, storage devices such as external storage devices, I / O interfaces, communication interfaces, etc. If the notification control device 204 is composed of a microcomputer, the processor operates (calculations, etc.) according to the instructions of the program loaded into memory to realize the processing for controlling the notification operation of the abnormal notification device 203.

[0071] The notification control device 204 is configured to acquire the fluid pressure (pressure signal) acquired by the pressure acquisition device 202 via wired or wireless communication. The notification control device 204 compares a preset pressure with the fluid pressure acquired by the pressure acquisition device 202, and is configured to instruct the abnormality notification device 203 to notify of an abnormality when the fluid pressure acquired by the pressure acquisition device 202 falls below the preset pressure. The abnormality notification device 203 is configured to notify of an abnormality in response to an instruction (instruction signal) from the notification control device 204. The abnormality notification device 203 is configured to output at least one of light, sound, or voice as a means of notifying an abnormality.

[0072] Furthermore, if the refrigeration system 1 is configured such that the abnormality notification device 203 performs notification operations according to the fluid pressure acquired by the pressure acquisition device 202, then the notification control device 204 may not be provided.

[0073] Compared to the high-pressure line, where pressure fluctuations are large depending on the operating state of the turbomachinery 2, it is easier to detect fluid leakage from the closed circuit 10 in the low-pressure line. The pressure acquisition device 202 monitors the pressure of the fluid flowing through the low-pressure line, and when the pressure drops below a predetermined pressure, the abnormality notification device 203 notifies the abnormality, thereby informing those who manage the operation and maintenance of the refrigeration system 1 of fluid leakage from the closed circuit 10. This embodiment (the embodiment shown in Figure 8) can be appropriately combined with the embodiments described above (the embodiments shown in Figures 1 to 7).

[0074] (Open / close valve) Figure 9 is a schematic diagram showing a refrigeration system 1 according to one embodiment of the present disclosure. As shown in Figure 9, a refrigeration system 1 according to several embodiments includes a fluid replenishment line 9 to which a fluid storage device 91 is connected at the upstream end, an on-off valve 92 for opening and closing the fluid replenishment line 9, and a pressure acquisition device (pressure sensor) 202 configured to acquire the pressure of the fluid flowing through the low-pressure line 201 (any of the expansion fluid line 32, return line 8 (illustrated example), motor housing chamber 13, or motor-side outlet passage 244).

[0075] Figure 10 is an explanatory diagram illustrating the opening and closing operation of the on-off valve 92 shown in Figure 9. Figure 10 shows a graph with time T on the horizontal axis and the fluid pressure P acquired by the pressure acquisition device 202 on the vertical axis. As shown in Figure 10, the on-off valve 92 is configured to open when the fluid pressure P acquired by the pressure acquisition device 202 falls below a predetermined pressure (set lower limit pressure TPL), and to close when the fluid pressure acquired by the pressure acquisition device 202 rises above the predetermined pressure (set lower limit pressure TPL) to a filling upper limit pressure (set upper limit pressure TPU).

[0076] In the embodiment shown in Figure 9, the refrigeration system 1 includes an on / off control device (controller) 205 configured to control the opening and closing operation of the on / off valve 92 in accordance with the fluid pressure acquired by the pressure acquisition device 202.

[0077] The opening / closing control device 205 is an electronic control unit for controlling the opening and closing operation of the on / off valve 92. The opening / closing control device 205 may be composed of analog circuits that can be manufactured relatively inexpensively, or it may be composed of a microcomputer consisting of a CPU (processor) (not shown), memory such as ROM or RAM, storage devices such as external storage devices, I / O interfaces, communication interfaces, etc. If the opening / closing control device 205 is composed of a microcomputer, the processor operates (calculates, etc.) according to the instructions of a program loaded into memory to realize the processing for controlling the opening and closing operation of the on / off valve 92.

[0078] The on / off control device 205 is configured to acquire the fluid pressure (pressure signal) acquired by the pressure acquisition device 202 via wired or wireless communication. The on / off control device 205 compares a preset pressure (set lower limit pressure TPL) with the fluid pressure acquired by the pressure acquisition device 202, and when the fluid pressure acquired by the pressure acquisition device 202 falls below the set lower limit pressure TPL (time T1), it is configured to instruct the on / off valve 92 to open. The on / off control device 205 also compares a preset pressure (set upper limit pressure TPU) with the fluid pressure acquired by the pressure acquisition device 202, and when the fluid pressure acquired by the pressure acquisition device 202 rises above the set upper limit pressure TPU (time T2), it is configured to instruct the on / off valve 92 to close. The on / off valve 92 is configured to open and close in response to instructions (instruction signals) from the on / off control device 205.

[0079] If the refrigeration system 1 is a self-controlled valve configured to open and close in accordance with the fluid pressure acquired by the pressure acquisition device 202, then it is not necessary to provide an opening / closing control device 205.

[0080] The low-pressure line 201 is easier to detect fluid leakage from the closed circuit 10 compared to the high-pressure line, which experiences large pressure fluctuations depending on the operating state of the turbomachinery 2. The pressure acquisition device 202 monitors the pressure of the fluid flowing through the low-pressure line 201, and the on-off valve 92 opens and closes according to the pressure, so that when the fluid in the closed circuit 10 becomes insufficient, fluid is automatically replenished via the fluid replenishment line 9. This embodiment (the embodiment shown in Figure 9) can be appropriately combined with the embodiments described above (the embodiments shown in Figures 1 to 8).

[0081] In some embodiments of the refrigeration system 1, the regenerative heat exchanger 6 described above is a plate heat exchanger, a printed circuit type heat exchanger, or a laminated heat exchanger. The regenerative heat exchanger 6 is relatively large within the refrigeration system 1. By using a plate heat exchanger, a printed circuit type heat exchanger, or a laminated heat exchanger for the regenerative heat exchanger 6, the size of the regenerative heat exchanger 6, and consequently the size of the refrigeration system 1, can be reduced.

[0082] 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 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. Furthermore, in this specification, expressions describing shapes such as quadrilaterals and cylindrical shapes shall not only represent geometrically precise quadrilaterals and cylindrical shapes, but also shapes that include uneven surfaces, chamfered surfaces, etc., to the extent that the same effect can be achieved. Furthermore, in this specification, the expressions “equipment,” “includes,” or “possess” of a component are not exclusive expressions that exclude the existence of other components.

[0083] 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.

[0084] The contents described in some of the embodiments above can be understood, for example, as follows:

[0085] [1] A refrigeration system (1) according to at least one embodiment of the present disclosure is A refrigeration system (1) for cooling a heat transfer medium for supplying cold energy to an object to be cooled, A turbomachinery (2) comprising a turbine (21), a compressor (22), and an electric motor (23), A closed loop (3) includes a compressed fluid line (31) for guiding the compressed fluid, which is the fluid compressed by the compressor (22), to the turbine (21), and an expanded fluid line (32) for guiding the expanded fluid, which is the fluid expanded by the turbine (21), to the compressor (22), A cooler (4) configured to cool the compressed fluid flowing through the compressed fluid line (31), A heat transfer medium cooler (5) is configured to perform heat exchange between the expanding fluid flowing in the expansion fluid line (32) and the heat transfer medium, A regenerative heat exchanger (6) is configured to perform heat exchange between the compressed fluid that has passed through the cooler (4) and the expanded fluid that has passed through the heat transfer cooler (5), The system includes an electric motor cooling line (7) for extracting the compressed fluid from between the cooler (4) and the regenerative heat exchanger (6) of the compressed fluid line (31) and supplying it to a casing (24) that houses the electric motor (23).

[0086] According to the configuration described in [1] above, by using the compressed fluid flowing between the cooler (4) and the regenerative heat exchanger (6) of the compressed fluid line (31) to cool the electric motor (23), stable cooling of the electric motor (23) becomes possible regardless of the operating state of the turbomachinery (2). This improves the robustness of the refrigeration system (1). If a fluid cooled by an external device of the refrigeration system (1) were used to cool the electric motor (23), the cooling temperature of the electric motor (23) may change depending on the state of the device, which could lead to unstable cooling of the electric motor (23). Furthermore, the compressed fluid flowing between the cooler (4) and the regenerative heat exchanger (6) of the compressed fluid line (31) is at a temperature more suitable for use as a refrigerant for cooling the electric motor (23) compared to the compressed fluid flowing upstream of the cooler (4) of the compressed fluid line (31) or the compressed fluid flowing downstream of the regenerative heat exchanger (6) of the compressed fluid line (31).

[0087] [2] In some embodiments, the refrigeration system (1) described in [1] above, The system further includes a return line (8) for returning the compressed fluid supplied to the casing (24) by the electric motor cooling line (7) from the casing (24) to the downstream side of the expansion fluid line (32) beyond the heat transfer medium cooler (5).

[0088] According to the configuration described in [2] above, the return line (8) allows the fluid used to cool the electric motor (23) to be returned to the closed loop (3). By making the electric motor cooling line (7), the return line (8), and the casing (24) part of the closed circuit (10) formed by the refrigeration system (1), leakage of fluid to the outside of the refrigeration system (1) can be suppressed, thereby improving the robustness of the refrigeration system (1).

[0089] [3] In some embodiments, the refrigeration system (1) described in [2] above, The system further includes a fluid replenishment line (9) for replenishing the fluid flowing through the closed loop (3), The fluid replenishment line (9) was connected to the electric motor cooling line (7) or the return line (8).

[0090] According to the configuration described in [3] above, the electric motor cooling line (7) and the return line (8) are locations where the fluid temperature is 0°C or higher during operation of the refrigeration system (1), and the amount of heat dissipated to the outside of the refrigeration system (1) when the fluid replenishment line (9) is connected can be suppressed.

[0091] [4] In some embodiments, the refrigeration system (1) described in [3] above, The fluid replenishment line (9) was connected to the return line (8).

[0092] According to the configuration described in [4] above, the return line (8) is a point where the fluid temperature is at room temperature during operation of the refrigeration system (1), and when the fluid replenishment line (9) is connected, heat input from outside the refrigeration system (1) and heat dissipation to the outside of the refrigeration system (1) can be suppressed. As a result, the refrigeration system (1) can maintain its refrigeration performance, thereby improving its reliability. In addition, the return line (8) is a low-pressure line where the fluid pressure is relatively low during operation of the refrigeration system (1), and there is a low possibility of fluid flowing back into the fluid replenishment line (9) when the fluid replenishment line (9) is connected, thus improving the reliability of fluid replenishment via the fluid replenishment line (9) during operation of the refrigeration system (1).

[0093] [5] In some embodiments, the refrigeration system (1) described in [2] above, The system further includes a fluid replenishment line (9) for replenishing the fluid flowing through the closed loop (3), Inside the casing (24), there is a motor housing chamber (13) for housing the electric motor (23), a motor-side inlet passage (242) for guiding the fluid from the electric motor cooling line (7) to the motor housing chamber (13), and a motor-side outlet passage (244) for guiding the fluid from the motor housing chamber (13) to the return line (8). The fluid replenishment line (9) was connected to the motor housing chamber (13) or the motor-side outlet passage (244).

[0094] According to the configuration described in [5] above, the motor housing chamber (13) and the motor-side outlet passage (244) are locations where the fluid temperature is at room temperature during operation of the refrigeration system (1), and when the fluid replenishment line (9) is connected, heat input from outside the refrigeration system (1) and heat dissipation to the outside of the refrigeration system (1) can be suppressed. As a result, the refrigeration system (1) can maintain its refrigeration performance, thereby improving its reliability. In addition, the motor housing chamber (13) and the motor-side outlet passage (244) are low-pressure lines where the fluid pressure is relatively low during operation of the refrigeration system (1), and when the fluid replenishment line (9) is connected, there is a low possibility of fluid flowing back into the fluid replenishment line (9), thus improving the reliability of fluid replenishment via the fluid replenishment line (9) during operation of the refrigeration system (1).

[0095] [6] In some embodiments, the refrigeration system (1) described in [2] above, The system further includes a fluid replenishment line (9) for replenishing the fluid flowing through the closed loop (3), The fluid replenishment line (9) was connected to the expansion fluid line (32) downstream of the regenerative heat exchanger (6), or to the compression fluid line (31) upstream of the regenerative heat exchanger (6).

[0096] According to the configuration described in [6] above, the area downstream of the regenerative heat exchanger (6) in the expansion fluid line (32) and the area upstream of the regenerative heat exchanger (6) in the compression fluid line (31) are locations where the fluid temperature is 0°C or higher during operation of the refrigeration system (1), and the amount of heat released to the outside of the refrigeration system (1) when the fluid replenishment line (9) is connected can be suppressed.

[0097] [7] In some embodiments, the refrigeration system (1) described in [6] above, The fluid replenishment line (9) was connected downstream of the regenerative heat exchanger (6) on the expansion fluid line (32).

[0098] According to the configuration described in [7] above, the part of the expansion fluid line (32) downstream of the regenerative heat exchanger (6) is at room temperature during operation of the refrigeration system (1), and when the fluid replenishment line (9) is connected, heat input from outside the refrigeration system (1) and heat dissipation to the outside of the refrigeration system (1) can be suppressed. As a result, the refrigeration system (1) can maintain its refrigeration performance, thereby improving its reliability. In addition, the expansion fluid line (32) is a low-pressure line where the fluid pressure is relatively low during operation of the refrigeration system (1), and there is a low possibility of fluid flowing back into the fluid replenishment line (9) when the fluid replenishment line (9) is connected, thus improving the reliability of fluid replenishment via the fluid replenishment line (9) during operation of the refrigeration system (1).

[0099] [8] In some embodiments, the refrigeration system (1) is as described in any of [3] to [7] above, The fluid supplied via the fluid replenishment line (9) is configured to pressurize the fluid flowing through the closed loop (3) to a pressure higher than atmospheric pressure.

[0100] According to the configuration described in [8] above, the refrigeration capacity of the refrigeration system (1) can be improved by pressurizing the closed circuit (10) that constitutes the refrigeration system (1), such as a closed loop (3), with the fluid replenished via the fluid replenishment line (9), thereby enabling the refrigeration system (1) to be made smaller and have a larger capacity.

[0101] [9] In some embodiments, the refrigeration system (1) described in any of [2] to [8] above, The return line (8) was connected downstream of the regenerative heat exchanger (6) in the expansion fluid line (32).

[0102] According to the configuration described in [9] above, by connecting the downstream end (82) of the return line (8) downstream of the regenerative heat exchanger (6) of the expansion fluid line (32), it is possible to suppress the reduction in the temperature difference between the two fluids performing heat exchange in the regenerative heat exchanger (6) due to the fluid introduced into the expansion fluid line (32) through the return line (8).

[0103]

[10] In some embodiments, the refrigeration system (1) is as described in any of [2] to [9] above, A pressure acquisition device (202) configured to acquire the pressure of the fluid flowing through the expansion fluid line (32) or the return line (8), The system further includes an abnormality notification device (203) configured to notify of an abnormality when the pressure of the fluid acquired by the pressure acquisition device (202) falls below a predetermined pressure.

[0104] According to the configuration described in

[10] above, the expansion fluid line (32) and the return line (8) are low-pressure lines where the fluid pressure is relatively low during operation of the refrigeration system (1). Compared to high-pressure lines, which experience large pressure changes depending on the operating state of the turbomachinery (2), it is easier to detect fluid leakage from the closed circuit (10) in low-pressure lines. The pressure acquisition device (202) monitors the pressure of the fluid flowing through the low-pressure line, and when the pressure drops below a predetermined pressure, the abnormality notification device (203) notifies the abnormality, thereby informing those who manage the operation and maintenance of the refrigeration system (1) of fluid leakage from the closed circuit (10).

[0105]

[11] In some embodiments, the refrigeration system (1) described in any of [3] to [9] above, A fluid storage device (91) configured to store the aforementioned fluid, the fluid storage device (91) to which the fluid replenishment line (9) is connected, A pressure acquisition device (202) configured to acquire the pressure of the fluid flowing through the expansion fluid line (32) or the return line (8), The system further comprises an on / off valve (92) for opening and closing the fluid replenishment line (9), The on-off valve (92) is configured to open when the pressure of the fluid acquired by the pressure acquisition device (202) falls below a predetermined pressure, and to close when the pressure of the fluid acquired by the pressure acquisition device (202) rises above a filling upper limit pressure which is higher than the predetermined pressure.

[0106] According to the configuration described in

[11] above, the expansion fluid line (32) and the return line (8) are low-pressure lines where the fluid pressure is relatively low during operation of the refrigeration system (1). Low-pressure lines are easier to detect fluid leakage from the closed circuit (10) than high-pressure lines, which experience large pressure changes depending on the operating state of the turbomachinery (2). A pressure acquisition device (202) monitors the pressure of the fluid flowing through the low-pressure lines, and the on-off valve (92) opens and closes according to the pressure, so that when the fluid in the closed circuit (10) becomes insufficient, fluid is automatically replenished via the fluid replenishment line (9).

[0107]

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

[11] above, The turbomachinery (2) is Rotating shaft (25) and The turbine (21) is attached to one side of the rotating shaft (25), The compressor (22) is attached to the other side of the rotating shaft (25), The electric motor (23) is provided between the compressor (22) and the turbine (21), and includes a rotor (231) attached to the rotating shaft (25) and a stator (232) positioned between the rotor (231) and the rotor (231) with a gap in between so as to cover the outer circumference of the rotor (231), The system comprises a motor housing chamber (13) for housing the electric motor (23), and a casing (24) having a motor-side inlet passage (242) for guiding the fluid from the electric motor cooling line (7) to the motor housing chamber (13).

[0108] According to the configuration described in

[12] above, the electric motor (23) can be cooled by the fluid introduced into the motor housing chamber (13) through the electric motor cooling line (7) and the motor side inlet passage (242).

[0109]

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

[12] above, The turbomachinery (2) includes gas bearings (26, 27, 28) that rotatably support the rotating shaft (25).

[0110] According to the configuration described in

[13] above, by employing gas bearings as the bearings (26, 27, 28) of the turbomachinery (2), an oil-free system can be achieved. This avoids the problem of reduced oil fluidity at low temperatures, thereby improving the reliability of the refrigeration system (1) at low temperatures. Furthermore, since the refrigeration system (1) does not require a mechanism or structure for supplying oil to the bearings (26, 27, 28), the turbomachinery (2) can be made smaller, and consequently, the refrigeration system (1) can be made smaller. [Explanation of Symbols]

[0111] 1. Refrigeration System 2 Turbomachinery 3. Closed-loop 4 Cooler 5 Heat medium cooler 6 Regenerative heat exchanger 7 Electric motor cooling line 8. Return line 9. Fluid replenishment line 10 Closed circuit 11 Turbine housing 12 Compressor housing room 13 Motor housing 14 Exterior Walls 15. Turbine-side partition wall 16 Compressor-side partition wall 17 Turbine Casing 18 Compressor casing 21 Turbine 22 Compressors 23 Electric motor 24 Casing 25 rotation shaft 26 Turbine-side bearing 26A, 27A radial bearings 27 Compressor-side bearing 28 Thrust bearings 31 Compressed fluid line 32 Expansion fluid line 41 Heat exchange section 42 Refrigerant circulation line 43 Cooling device 44 Refrigerant pump 45 Radiator 46 Fans 91 Fluid storage device 92 Shut-off valves 103 Bearing cooling line 201 Low-voltage line 202 Pressure acquisition device 203 Anomaly notification device 204 Notification control device 205 Opening / closing control device

Claims

1. A refrigeration system for cooling a heat transfer medium that supplies cold energy to an object to be cooled, A turbomachinery equipped with a turbine, compressor and electric motor, A closed loop including a compressed fluid line for guiding the compressed fluid, which is the fluid compressed by the compressor, to the turbine, and an expanded fluid line for guiding the expanded fluid, which is the fluid expanded by the turbine, to the compressor, A cooler configured to cool the compressed fluid flowing through the compressed fluid line, A heat transfer medium cooler configured to perform heat exchange between the expanding fluid flowing in the expansion fluid line and the heat transfer medium, A regenerative heat exchanger configured to perform heat exchange between the compressed fluid that has passed through the cooler and the expanded fluid that has passed through the heat transfer cooler, The system includes an electric motor cooling line for extracting the compressed fluid from between the cooler and the regenerative heat exchanger of the compressed fluid line and supplying it to a casing that houses the electric motor. Refrigeration system.

2. The system further includes a return line for returning the compressed fluid supplied to the casing by the electric motor cooling line back from the casing to the downstream side of the expansion fluid line beyond the heat transfer medium cooler. The refrigeration system according to claim 1.

3. The system further comprises a fluid replenishment line for replenishing the fluid flowing through the closed loop, The fluid replenishment line is connected to the electric motor cooling line or the return line, The refrigeration system according to claim 2.

4. The fluid replenishment line is connected to the return line, The refrigeration system according to claim 3.

5. The system further comprises a fluid replenishment line for replenishing the fluid flowing through the closed loop, The casing is formed with a motor housing chamber for housing the electric motor, a motor-side inlet passage for guiding the fluid from the electric motor cooling line to the motor housing chamber, and a motor-side outlet passage for guiding the fluid from the motor housing chamber to the return line. The fluid replenishment line is connected to the motor housing chamber or the motor-side outlet passage, The refrigeration system according to claim 2.

6. The system further comprises a fluid replenishment line for replenishing the fluid flowing through the closed loop, The fluid replenishment line is connected downstream of the regenerative heat exchanger in the expansion fluid line, or upstream of the regenerative heat exchanger in the compression fluid line. The refrigeration system according to claim 2.

7. The fluid replenishment line is connected downstream of the regenerative heat exchanger in the expansion fluid line. The refrigeration system according to claim 6.

8. The fluid supplied via the fluid replenishment line is configured to pressurize the fluid flowing through the closed loop to a pressure higher than atmospheric pressure. A refrigeration system according to any one of claims 3 to 7.

9. The return line is connected downstream of the regenerative heat exchanger in the expansion fluid line. A refrigeration system according to any one of claims 2 to 7.

10. A pressure acquisition device configured to acquire the pressure of the fluid flowing through the expansion fluid line or the return line, The system further comprises an abnormality notification device configured to notify of an abnormality when the pressure of the fluid acquired by the pressure acquisition device falls below a predetermined pressure. A refrigeration system according to any one of claims 2 to 7.

11. A fluid storage device configured to store the aforementioned fluid, the fluid storage device to which the fluid replenishment line is connected, A pressure acquisition device configured to acquire the pressure of the fluid flowing through the expansion fluid line or the return line, The system further comprises an on / off valve for opening and closing the fluid replenishment line, The on-off valve is configured to open when the pressure of the fluid acquired by the pressure acquisition device falls below a predetermined pressure, and to close when the pressure of the fluid acquired by the pressure acquisition device rises above a filling upper pressure that is higher than the predetermined pressure. A refrigeration system according to any one of claims 3 to 7.

12. The aforementioned turbo machine, Rotating shaft and The turbine attached to one side of the rotating shaft, The compressor is attached to the other side of the rotating shaft, The electric motor is provided between the compressor and the turbine, and includes a rotor attached to the rotating shaft and a stator positioned between the rotor and the rotor with a gap in between so as to cover the outer circumference of the rotor. A refrigeration system according to any one of claims 1 to 7, comprising: a motor housing chamber for housing the electric motor; and a casing having a motor-side inlet passage formed therein for guiding the fluid from the electric motor cooling line to the motor housing chamber.

13. The turbomachinery includes a gas bearing that rotatably supports the rotating shaft. The refrigeration system according to claim 12.

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