Cooling system

Abstract

To provide a cooling system capable of suppressing the effects of heat between a compressor and an expander.SOLUTION: A cooling system 10 includes a circulation flow path 12 where refrigerant gas flows, a screw type compressor 21 for discharging the refrigerant gas, a precooler included in a cooler unit 29, a screw type expander 22 for expanding the refrigerant gas cooled by the precooler, and a brine cooler using cold of the refrigerant gas flowing out of the expander for cooling cooled objects, the precooler and the brine cooler being unitized as a cooler unit 29, the compressor 21 including a compressor body 21a and a compressor drive part 21b, the expander 22 including an expander body 22a and an expander driven part 22b, the compressor 21 being arranged above the expander 22.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a cooling system that uses a refrigerant gas. [Background technology]

[0002] Conventionally, refrigerators and chillers have sometimes used a so-called air-type refrigeration cycle that does not include a liquefaction process.

[0003] The cold air supply unit disclosed in Patent Document 1 comprises an air compressor / expander, a water-to-air heat exchanger, an air-to-air heat exchanger, and air piping housed within a single rectangular casing. The air compressor / expander is comprised of an electric motor as a prime mover, a compressor, a gearbox, and an expander, all integrated together, and is installed on the casing base. The water-to-air heat exchanger and air-to-air heat exchanger are located in the upper space within the casing. The air piping connects the air compressor / expander, the water-to-air heat exchanger, and the air-to-air heat exchanger, and is arranged to fit within the casing. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-210484 Summary of the Invention [Problem to be solved by the invention]

[0005] In the cold air supply unit disclosed in Patent Document 1, the compressor is disposed on one side of the gearbox and the expander is disposed on the other side, which requires a large installation area for the air compression and expansion device, making it difficult to reduce the size of the entire unit.

[0006] Here, in the above-mentioned cold air supply unit, it is possible to reduce the size of the entire unit by narrowing the distance between the compressor and the expander.

[0007] However, in the above-mentioned cold air supply unit, it is difficult to place the compressor and the expander close to each other. That is, the compressor reaches a high temperature (for example, several tens to several hundred degrees Celsius), while the expander reaches a low temperature (for example, several tens to several hundred degrees Celsius below zero). Therefore, in the above-mentioned cold air supply unit, if the compressor, which reaches a high temperature, and the expander, which reaches a low temperature, are forcibly placed close to each other in order to reduce the size of the unit, there is a concern that thermal problems may occur between the compressor and the expander.

[0008] The present invention has been made in view of the above-mentioned problems, and has an object to suppress the influence of heat between the compressor and the expander. [Means for solving the problem]

[0009] A cooling system according to one aspect of the present invention is a cooling system that cools an object to be cooled using a refrigerant gas, and includes a circulation flow path, a screw compressor, a precooler, a screw expander, and a cooling unit. The circulation flow path has a high-pressure gas flow path and a low-pressure gas flow path, and the refrigerant gas flows through the circulation flow path. The screw compressor compresses the refrigerant gas and discharges it toward the high-pressure gas flow path. The precooler exchanges heat between the refrigerant gas in the high-pressure gas flow path and the refrigerant gas in the low-pressure gas flow path. The screw expander expands the refrigerant gas from the high-pressure gas flow path cooled by the precooler and discharges the refrigerant gas into the low-pressure gas flow path. The cooling unit cools the object to be cooled in the low-pressure gas flow path using the cold energy of the refrigerant gas discharged from the expander.

[0010] The compressor includes a compressor main body having a screw rotor and a compressor drive unit having a motor and driving the screw rotor in the compressor main body, and the expander includes an expander main body having a screw rotor and an expander driven unit having a generator and driven by the screw rotor in the expander main body.

[0011] In the cooling system according to this aspect, the compressor is disposed above the expander.

[0012] In the cooling system according to the above embodiment, the compressor is positioned above the expander, so that the compressor and expander can be positioned closer together than when both are positioned on the base of the casing as in Patent Document 1.

[0013] In addition, in the cooling system according to the above aspect, the compressor, which becomes hot during operation, is disposed above the expander, which becomes cold during operation, so that even when the compressor and expander are disposed close to each other, the heat generated by the compressor can be prevented from being transferred to the expander. Therefore, in the cooling system according to the above aspect, the compressor and expander can be disposed close to each other while preventing thermal problems from occurring.

[0014] In the cooling system according to the above aspect, the compressor and the expander may be arranged such that a rotation axis of the compressor main body and a rotation axis of the expander main body are substantially parallel to each other.

[0015] In the cooling system according to the above aspect, the rotation axes of the compressor body and the expander body are arranged so as to be approximately parallel to each other, thereby preventing the space required for arranging the compressor and the expander from becoming unnecessarily large.

[0016] In the cooling system according to the above aspect, the cooling unit may be configured with a first heat exchanger. Also, the precooler may be configured with a second heat exchanger. Furthermore, the second heat exchanger may be disposed above the first heat exchanger.

[0017] In the cooling system according to the above aspect, the second heat exchanger into which the high-temperature gas flows is disposed above the first heat exchanger constituting the cooling unit, so that the heat generated in the second heat exchanger can be prevented from being transferred to the first heat exchanger. Therefore, in the cooling system according to the above aspect, even if the cooling unit is disposed close to the first heat exchanger, the cooling efficiency of the cooling unit can be prevented from being reduced by the heat generated in the second heat exchanger.

[0018] In the cooling system according to the above aspect, the first heat exchanger and the second heat exchanger may be integrally configured.

[0019] In the cooling system according to the above aspect, the first heat exchanger and the second heat exchanger are integrally configured, so the entire system can be made more compact than when the first heat exchanger and the second heat exchanger are provided separately and arranged with a space between them. In other words, if the first heat exchanger and the second heat exchanger are not integrally configured, frames, brackets, etc. are needed to install them, and this requires space.

[0020] On the other hand, in the cooling system according to the above aspect, in which the first heat exchanger and the second heat exchanger are integrally configured, there is no need for a frame or bracket for separately arranging the first heat exchanger and the second heat exchanger, and therefore the cooling system according to the above aspect is advantageous in that the entire system can be made even more compact.

[0021] The cooling system according to the above aspect may further include a gas cooler provided in the high-pressure gas path between the compressor and the precooler, for cooling the refrigerant gas in the high-pressure gas path flowing from the compressor to the precooler. The gas cooler may be a third heat exchanger. The third heat exchanger may be disposed above the second heat exchanger.

[0022] In the cooling system according to the above aspect, the third heat exchanger is disposed above the second heat exchanger constituting the precooler, thereby suppressing heat transfer from the gas cooler into which high-temperature refrigerant gas flows to the precooler.

[0023] In the cooling system according to the above aspect, the object to be cooled may be brine, and the cooling system may further include a brine circulation device that circulates the brine between the cooling unit and a demand-side heat load. The brine circulation device may also include a brine tank that stores the brine, a brine pump that circulates the brine, and a heater that adjusts the temperature of the brine that flows into the demand-side heat load. In this case, the brine tank, the brine pump, and the heater in the brine circulation device may be located below the expander and the cooling unit.

[0024] In the cooling system according to the above aspect, the brine tank, brine pump, and heater are arranged below the expander and cooling unit, so that these components of the brine circulation device are prevented from being affected by heat from the expander and cooling unit.

[0025] The cooling system according to the above aspect may further include a heat insulating material that covers the surfaces of the expander, the cooling section, and the precooler.

[0026] In the cooling system according to the above aspect, the expansion machine, the cooling section, and the precooler are covered with heat insulating materials, so that it is possible to prevent heat from entering these parts from the outside.

[0027] In the cooling system according to the above aspect, the refrigerant gas may be nitrogen gas.

[0028] In the cooling system according to the above aspect, nitrogen gas is used as the refrigerant gas, so that the global warming potential (GWP) can be set to "0".

[0029] The cooling system according to the above aspect may further include a fan that generates an airflow from below the expander toward above it.

[0030] In the cooling system according to the above aspect, since the fan is provided, the temperature around the compressor can be lowered by the cold heat of the expander, and therefore the cooling system according to the above aspect can drive the compressor with high efficiency. [Effects of the Invention]

[0031] In the cooling system according to each of the above aspects, the influence of heat between the compressor and the expander can be suppressed. [Brief explanation of the drawings]

[0032] [Figure 1] 1 is a diagram schematically illustrating a cooling system according to a first embodiment. [Figure 2] FIG. 2 is a front view showing the arrangement of each part in the cooling system. [Figure 3] FIG. 2 is a side view showing the arrangement of the main parts of the cooling system. [Figure 4] FIG. 2 is a schematic diagram showing an arrangement of a rotary shaft of a compressor and a rotary shaft of an expander. [Figure 5] FIG. 2 is a partial front view showing the arrangement of a brine cooler and a precooler in the cooler unit. [Figure 6] FIG. 2 is a schematic diagram showing a connection between a brine cooler and a precooler and a compressor and an expander. [Figure 7] FIG. 10 is a schematic diagram showing a modified example of the connection between the brine cooler and precooler and the compressor and expander. [Figure 8] FIG. 2 is a front view showing the arrangement of an aftercooler relative to a precooler. [Figure 9] FIG. 2 is a schematic diagram for explaining a shaft seal configuration for a rotating shaft of a compressor. [Figure 10] FIG. 2 is a schematic diagram for explaining a shaft seal configuration of a rotary shaft of an expander. [Figure 11]FIG. 10 is a front view showing the configuration of a cooling system according to a first modified example. [Figure 12] FIG. 10 is a front view showing the configuration of a cooling system according to a second modification. [Figure 13] FIG. 6 is a diagram schematically illustrating a cooling system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0033] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are merely illustrative of the present invention, and the present invention is not limited to the following embodiments except for the essential configuration.

[0034] [First embodiment] 1. Schematic configuration of cooling system 10 The schematic configuration of a cooling system 10 according to this embodiment will be described with reference to FIG.

[0035] As shown in Fig. 1, cooling system 10 is a system configured to circulate refrigerant gas within a circulation flow path 12, lower the temperature of the refrigerant gas, and use the lowered temperature refrigerant gas to cool an object to be cooled. The object to be cooled in cooling system 10 according to this embodiment is brine. Cooling system 10 includes a brine circulation device 14 through which brine is circulated. Although not shown, the cooled brine is sent to a demand-side heat load to be cooled, and cools the demand-side heat load with cold energy.

[0036] In this embodiment, nitrogen gas is used as an example of the refrigerant gas circulating through the circulation flow path 12. However, the refrigerant gas is not limited to nitrogen gas, and may be, for example, air or HFC (hydrofluorocarbon).

[0037] The cooling system 10 includes a compressor 21, an aftercooler 27, an expander 22, and a brine cooler 23, which are arranged in the order of refrigerant gas flow in the circulation flow path 12. As the compressor 21 and the expander 22 are driven, the refrigerant gas flows through the circulation flow path 12 in this order: compressor 21, expander 22, and brine cooler 23. The refrigerant gas in the circulation flow path 12 undergoes a compression process and an expansion process, but does not undergo a phase change of the refrigerant gas such as condensation or evaporation, and flows in a gaseous state without any phase change. In other words, the cooling system 10 according to this embodiment is not a vapor compression cooling system, and is a system that does not include a condenser or an evaporator.

[0038] The circulation flow path 12 is composed of, in the flow direction of the refrigerant gas, a high-pressure gas flow path section 12a that is a section from the compressor 21 to the expander 22, and a low-pressure gas flow path section 12b that is a section from the expander 22 to the compressor 21. The high-pressure gas flow path section 12a is a section through which refrigerant gas compressed by the compressor 21 and thus attains high pressure flows. The low-pressure gas flow path section 12b is a section through which refrigerant gas expanded by the expander 22 and thus attains low pressure flows.

[0039] The compressor 21 is a screw-type compressor equipped with a pair of screw rotors. In a screw-type compressor, the volume of a compression chamber formed between the pair of screw rotors gradually decreases as the screw rotors rotate. The refrigerant gas introduced into the compressor 21 through the low-pressure gas flow path 12b is compressed thereby.

[0040] In the cooling system 10, the aftercooler 27 is a gas cooler that cools the refrigerant gas discharged from the compressor 21. In this embodiment, the aftercooler 27 is configured as a heat exchanger (third heat exchanger). For example, a plate heat exchanger, a finned tube heat exchanger, or a microchannel heat exchanger is used as the heat exchanger that configures the aftercooler 27. In the aftercooler 27, heat is exchanged between the refrigerant gas and a cooling fluid (water, for example), thereby cooling the refrigerant gas. That is, the aftercooler 27 removes excess heat from the refrigerant gas that has been heated by compression in the compressor 21.

[0041] A screw-type expander equipped with a pair of screw rotors is used as the expander 22. In a screw-type expander, the volume of an expansion chamber formed between the pair of screw rotors gradually increases as the screw rotors rotate. The refrigerant gas introduced into the expander 22 through the high-pressure gas flow path 12a is expanded by the expansion chamber.

[0042] The brine cooler 23 is a heat exchanger (first heat exchanger) that exchanges heat between the refrigerant gas flowing through the low-pressure gas passage section 12b and the brine (object to be cooled) flowing through the brine circulation device 14. In this embodiment, the heat exchanger that constitutes the brine cooler 23 may be, for example, a plate-type heat exchanger, a fin-tube-type heat exchanger, or a microchannel-type heat exchanger. In the brine cooler 23, the brine, which is the object to be cooled, is cooled by using the cold energy of the refrigerant gas flowing out from the expander 22. That is, in this embodiment, the brine cooler 23 is provided as a cooling section 25 that cools the brine.

[0043] The brine circulation device 14 is a device that circulates brine between the cooling unit 25 (brine cooler 23) and a demand-side heat load. The brine circulation device 14 includes a brine pipe 31, a brine pump 32, a brine tank 33, and a heater 34. The brine pipe 31 is provided so as to form a closed loop between the demand-side heat load (not shown) to be cooled and the brine cooler 23.

[0044] The brine pump 32 is a pump that circulates the brine in the brine pipe 31. That is, the brine in the brine pipe 31 is circulated in a closed loop by driving the brine pump 32.

[0045] The brine tank 33 is a storage tank for storing brine, which is provided between a demand heat load (not shown) in the brine circulation path and the brine pump 32. The brine stored in the brine tank 33 is sent to the brine cooler 23 by driving the brine pump 32.

[0046] The heater 34 is inserted between the brine cooler 23 and a demand heat load (not shown) in the brine distribution path, and adjusts the temperature of the brine based on the demand of the demand heat load. The location of the heater 34 is not limited to the location shown in Figure 1, and may be located downstream of the brine tank 33 in the brine distribution path.

[0047] The brine piping 31 has an inlet flow path section 31a, which is a section for introducing brine into the brine cooler 23, and an outlet flow path section 31b, which is a section for discharging brine from the brine cooler 23. The brine tank 33 and the brine pump 32 are provided in the inlet flow path section 31a. The heater 34 is provided in the outlet flow path section 31b. However, as described above, the heater 34 may be provided anywhere downstream of the brine tank 33 in the brine distribution path.

[0048] In addition to the above-described configuration, the cooling system 10 also includes a precooler 28. The precooler 28 is arranged in the circulation flow path 12 so as to be connected to the high-pressure gas flow path portion 12a and the low-pressure gas flow path portion 12b. In this embodiment, the precooler 28 is configured as a heat exchanger (second heat exchanger). For example, a plate heat exchanger, a fin-tube heat exchanger, a microchannel heat exchanger, or the like is used as the heat exchanger that constitutes the precooler 28.

[0049] The precooler 28 is provided to exchange heat between the refrigerant gas flowing between the aftercooler 27 and the expander 22 in the high-pressure gas passage section 12a and the refrigerant gas flowing in the low-pressure gas passage section 12b. That is, in the precooler 28, the refrigerant gas before flowing into the expander 22 is cooled using the cold energy of the refrigerant gas after the brine cooler 23 supplies cold energy to the brine. In the cooling system 10, the precooler 28 and the brine cooler 23 are housed in a single housing and unitized as a cooler unit 29.

[0050] Although detailed illustrations are omitted here, the cooling system 10 according to this embodiment further includes a heat insulating material (not shown) that covers the surfaces of the expander 22, the brine cooler 23, and the precooler 28. This makes it possible to minimize the influence of the external environment on the refrigerant gas and brine in each of the expander 22, the brine cooler 23, and the precooler 28.

[0051] 2. Arrangement of Components in Cooling System 10 The arrangement of each part of the cooling system 10 will be described with reference to Figures 2 and 3. In the following figures, including Figures 2 and 3, "+Z" indicates the vertically upward direction, and "-Z" indicates the vertically downward direction. Furthermore, "X direction" and "Y direction" indicate the horizontal direction. In Figure 2, the flow of refrigerant gas is indicated by arrows.

[0052] As shown in FIGS. 2 and 3, in the cooling system 10, the gas pipes 12a-12g that constitute the circulation flow path 12, the brine circulation device 14, the compressor 21, the expander 22, the aftercooler 27, and the cooler unit 29 are housed inside a single housing 40. The housing 40 is formed into a box shape by an upper frame 40a, a lower frame 40b, and side frames 40c. The housing 40 also includes an intermediate frame 40d that connects the side frames 40c to each other. The intermediate frame 40d is disposed between the upper frame 40a and the lower frame 40b so as to extend in the X direction, etc. The components 12, 14, 21, 22, 27, and 29 that constitute the cooling system 10 are disposed between the upper frame 40a and the lower frame 40b in the Z direction. Furthermore, the components 12, 14, 21, 22, 27, and 29 that make up the cooling system 10 are disposed between the side frames 40c in the X and Y directions. Although not shown in detail, the components 12, 14, 21, 22, 27, and 29 are attached to the frames 40a, 40b, and 40c or the intermediate frame 40d directly or via brackets.

[0053] The brine circulation device 14 is disposed on the lower frame 40b. As shown in FIGS. 2 and 3, the brine circulation device 14 has a rectangular box-shaped outer case. A portion of the brine piping 31, a brine pump 32, a brine tank 33, and a heater 34 are housed inside the outer case of the brine circulation device 14. A heat insulating material is attached to the box (outer case) of the brine circulation device 14. That is, the outside of each component housed inside the outer case (a portion of the brine piping 31, the brine pump 32, the brine tank 33, and the heater 34) is covered with a heat insulating material. However, each component of the brine circulation device 14 (a portion of the brine piping 31, the brine pump 32, the brine tank 33, and the heater 34) may also be individually covered with a heat insulating material.

[0054] Furthermore, some of the components of the brine circulation device 14 do not need to be housed in the exterior case. In this case, some of the components of the brine circulation device 14 that are arranged outside the exterior case may be arranged outside the housing 40.

[0055] Inside the housing 40, the expander 22 and the compressor 21 are disposed above the brine circulation device 14. In other words, the brine circulation device 14, which includes the brine pump 32, the brine tank 33, and the heater 34, is disposed below the expander 22 and the compressor 21.

[0056] The compressor 21 and the expander 22 are arranged in a vertical relationship such that the compressor 21 is disposed at a higher position than the expander 22.

[0057] 2, the compressor 21 includes a compressor main body 21a and a compressor drive unit 21b. The compressor main body 21a has the pair of screw rotors. The compressor drive unit 21b has a motor that generates a driving force for driving the pair of screw rotors.

[0058] The expander 22 includes an expander main body 22a and an expander driven part 22b. The expander main body 22a has the pair of screw rotors. The expander driven part 22b has a generator that generates electricity by rotation of the screw rotors.

[0059] In this embodiment, both the compressor body 21a and the compressor driving section 21b of the compressor 21 are disposed so as to be located higher than both the expander body 22a and the expander driven section 22b of the expander 22. However, with regard to the vertical arrangement of the compressor 21 and the expander 22, it is sufficient that at least the compressor body 21a of the compressor 21 is disposed higher than the expander body 22a of the expander 22.

[0060] A lubricating oil device 30 is disposed in the housing 40 between the brine circulation device 14 and the expander 22 in the vertical direction. The lubricating oil device 30 supplies lubricating oil to bearings of the compressor 21, the expander 22, and the like. The location of the lubricating oil device 30 is not limited to the location shown in FIGS. 2 and 3, and it may be located outside the housing 40.

[0061] Inside the housing 40, the cooler unit 29 and the aftercooler 27 are arranged above the brine circulation device 14. In other words, the brine circulation device 14, which includes the brine pump 32, the brine tank 33, and the heater 34, is arranged below the cooler unit 29. In other words, the brine circulation device 14 is arranged below the brine cooler 23 (cooling section 25) included in the cooler unit 29.

[0062] Aftercooler 27 constituting the gas cooler is disposed above cooler unit 29. That is, the first heat exchanger constituting aftercooler 27 is disposed above the second heat exchanger constituting precooler 28 included in cooler unit 29.

[0063] The aftercooler 27 and the cooler unit 29 are arranged at a distance on the +X side from the compressor 21 and the expander 22. The aftercooler 27 is arranged in a range that partially overlaps with the compressor 21 in the height direction. The aftercooler 27 is arranged so that its upper end is lower than the upper end of the compressor 21. The cooler unit 29 is arranged in a range that partially overlaps with the compressor 21 and the front part of the expander 22 in the height direction.

[0064] The high-pressure gas passage section 12a has gas pipes 12c to 12e. As shown in FIG. 2, the gas pipe 12c is a pipe that connects the compressor 21 and the aftercooler 27. The gas pipe 12d is a pipe that connects the aftercooler 27 and the precooler 28 (see FIG. 1) of the cooler unit 29. The gas pipe 12e is a pipe that connects the precooler 28 (see FIG. 1) of the cooler unit 29 and the expander 22. The low-pressure gas passage section 12b has gas pipes 12f and 12g. The gas pipe 12f is a pipe that connects the expander 22 and the brine cooler 23 (see FIG. 1) of the cooler unit 29. The gas pipe 12g is a pipe that connects the precooler 28 (see FIG. 1) of the cooler unit 29 and the compressor 21. Here, the gas pipe 12f is positioned lower than the gas pipe 12e because, when the cooling system 10 is operating, the refrigerant gas flowing through the gas pipe 12e becomes hotter than the refrigerant gas flowing through the gas pipe 12f.

[0065] The brine cooler 23 (see FIG. 1) of the cooler unit 29 and the brine circulation device 14 are connected by a pipe constituting the inlet flow path portion 31a and a pipe constituting the outlet flow path portion 31b.

[0066] In this embodiment, the gas pipes 12c to 12g and the flow path portions 31a and 31b are housed in the housing 40. However, some of the gas pipes 12c to 12g and the flow path portions 31a and 31b may be disposed outside the housing 40.

[0067] 3. Arrangement of the Rotating Shaft of the Compressor Body 21a and the Rotating Shaft of the Expander Body 22a The arrangement of the rotary shaft of the compressor body 21a and the rotary shaft of the expander body 22a will be described with reference to FIG.

[0068] As described above, the compressor body 21a of the compressor 21 and the expander body 22a of the expander 22 each have a pair of screw rotors. As shown in Fig. 4, the pair of screw rotors in the compressor body 21a are configured to be rotationally driven by a rotation shaft Ax21 arranged along the X direction. The pair of screw rotors in the expander body 22a are configured to be rotationally driven by a rotation shaft Ax22 arranged along the X direction.

[0069] 4, the rotation shaft Ax21 of the compressor 21 and the rotation shaft Ax22 of the expander 22 are disposed so as to extend horizontally (perpendicular to the vertical direction). However, each of the rotation shaft Ax21 and the rotation shaft Ax22 does not have to be disposed so as to extend completely horizontally.

[0070] The compressor 21 and the expander 22 are arranged such that the rotation axes Ax21 and Ax22 are substantially parallel to each other. Note that the rotation axes Ax21 and Ax22 do not have to be completely parallel to each other. For example, when manufacturing the cooling unit 10, an assembly error between the compressor 21 and the expander 22 is allowed.

[0071] 4. Arrangement of the brine cooler 23 and the precooler 28 in the cooler unit 29 The arrangement of the brine cooler 23 and the precooler 28 in the cooler unit 29 will be described with reference to FIG.

[0072] As described above, the cooler unit 29 is configured such that the brine cooler 23 and the precooler 28 are unitized. As shown in Fig. 5, in the cooler unit 29, the second heat exchanger that constitutes the precooler 28 is disposed above the first heat exchanger that constitutes the brine cooler 23 (cooling section 25). Note that Fig. 5 shows the cooler unit 29 in which the brine cooler 23 and the precooler 28 are housed in a single housing (exterior case), but this is not limiting. In other words, it is sufficient that the brine cooler 23 and the precooler 28 are unitized, and it is not essential that they be housed in a single exterior case.

[0073] In this embodiment, a gap is provided between the precooler 28 and the brine cooler 23 in the vertical direction. The brine cooler 23 and the precooler 23 are connected by a gas pipe 12h arranged in the gap. The gas pipe 12h is a pipe included in the low-pressure gas flow path section 12b.

[0074] The connection between the brine cooler 23 and the precooler 28 will be described with reference to Figures 6 and 7. Figure 6 is a diagram showing the connection used in this embodiment, and Figure 7 is a diagram showing a connection in a modified example.

[0075] As shown in Fig. 6, in the cooling system 10 according to this embodiment, the refrigerant gas discharged from the expander 22 is introduced into the brine cooler 23 to cool the brine. In this case, the brine cooler 23 is configured so that the refrigerant gas flows from bottom to top within the brine cooler 23, and the brine flows from top to bottom. The refrigerant gas discharged upward from the brine cooler 23 is introduced directly into the precooler 28, where it exchanges heat with the refrigerant gas in the path from the compressor 21 to the expander 22. In this case, the precooler 28 is configured so that the refrigerant gas flows from bottom to top within the precooler 28.

[0076] In contrast, as shown in Fig. 7, in the cooling system 10 according to the modified example, the refrigerant gas discharged from the expander 22 is introduced into the brine cooler 23. In the brine cooler 23, the refrigerant gas flows downward, and the brine flows upward, similar to the configuration shown in Fig. 6. The refrigerant gas that has cooled the brine is once discharged to the outside of the cooler unit 29 (indicated by A in Fig. 7).

[0077] The refrigerant gas discharged to the outside of cooler unit 29 is introduced into precooler 28 and exchanges heat with the refrigerant gas in the path from compressor 21 to expander 22. In this case, precooler 28 of the modified example is also configured so that the refrigerant gas flows from the bottom to the top within precooler 28.

[0078] In the configuration shown in Fig. 6 and the configuration shown in Fig. 7, the refrigerant gas and brine flow in a countercurrent relationship in both the brine cooler 23 of the embodiment and the modified brine cooler 23. Therefore, whether the configuration shown in Fig. 6 or the modified configuration shown in Fig. 7 is adopted, heat exchange with high temperature efficiency is possible in the brine cooler 23. Note that in the configuration shown in Fig. 6 or the modified configuration shown in Fig. 7, the refrigerant gas and brine in the brine cooler 23 can also be configured to flow in a parallel current relationship.

[0079] 5. Arrangement of the precooler 28 and aftercooler 27 of the cooler unit 29 The arrangement of the precooler 28 and the aftercooler 27 of the cooler unit 29 will be described with reference to FIG.

[0080] As shown in FIG. 8, the precooler 28 is disposed so as to be located above the brine cooler 23, and is disposed in an upper portion inside the unit case that constitutes the exterior of the cooler unit 29.

[0081] On the other hand, the aftercooler 27 is disposed above the cooler unit 29 with a gap therebetween. However, the gap between the cooler unit 29 and the aftercooler 27 is not necessarily required.

[0082] In the cooling system 10 according to this embodiment, the third heat exchanger constituting the aftercooler 27 is disposed above the second heat exchanger constituting the precooler .

[0083] 6. Shaft seal structure of each rotating shaft 21h, 22h of the compressor 21 and the expander 22 The shaft seal structures of the rotary shafts 21h and 22h of the compressor 21 and the expander 22 will be described with reference to FIGS.

[0084] As shown in Fig. 9, the compressor 21 has a compression unit 21c in a compressor body 21a, and a motor 21d and an inverter 21e in a compressor drive unit 21b. The compression unit 21c has a pair of screw rotors. The motor 21d generates a driving force for driving the pair of screw rotors. The inverter 21e adjusts the rotation speed of the motor 21d to a preset reference frequency.

[0085] The drive shaft 21g of the motor 21d is connected to the rotary shaft 21h of the compression unit 21c via the speed increase / decrease gear 21i. However, the rotary shaft 21h of the compressor body 21a may be directly connected to the drive shaft 21g of the motor 21d.

[0086] The rotating shaft 21h of the compressor body 21a is disposed so as to extend from the screw rotor on both sides in the axial direction. A bearing 21k and a shaft seal 21j are provided on the rotating shaft 21h. The bearing 21k supports the rotating shaft 21h so that it can rotate freely. The shaft seal 21j is provided on the rotating shaft 21h between the bearing 21k and the compression section 21c, and prevents oil from the bearing 21k from flowing into the compression section 21c. In other words, in the oil-free compressor 21, the shaft seal 21j is provided to prevent oil from the bearing 21c from entering the screw rotor of the compression section 21c.

[0087] A supply path 37 for supplying a seal gas from a supply source (not shown) and a discharge path 38 for discharging the seal gas supplied to the shaft seal 21j into the atmosphere are connected to the shaft seal 21j. In this embodiment, nitrogen gas, the same as the refrigerant gas, is used as the seal gas. However, when air is used as the refrigerant gas, air is also used as the seal gas.

[0088] Next, as shown in Fig. 10, the expander 22 has an expansion section 22c in an expander main body 22a, and an expander driven section 22b having a generator 22d and an inverter 22e. The expansion section 22c has a pair of screw rotors. The generator 22d is driven by the pair of screw rotors. Electric power generated by the generator 22d as the screw rotors rotate is converted by the inverter 22e and supplied to other sections of the cooling system 10 or to outside the system.

[0089] An input shaft 22g of the generator 22d is connected to a rotating shaft 22h of the expansion section 22c. The input shaft 22g and the rotating shaft 22f may be connected via a speed increase / decrease gear interposed therebetween, or may be directly connected.

[0090] The expander body 22a has a rotating shaft 22h arranged to extend axially from the screw rotor of the expansion section 22c on both sides. The rotating shaft 22h is also provided with a bearing (not shown) and a shaft seal 22j. The bearing supports the rotating shaft 22h so that it can rotate freely. The shaft seal 22j is provided between the bearing of the rotating shaft 22h and the expansion section 22c, and prevents oil from the bearing from flowing into the expansion section 22c.

[0091] A supply path 42 for supplying a seal gas from a supply source (not shown) and a discharge path 43 for releasing the seal gas supplied to the shaft seal 22j into the atmosphere are connected to the shaft seal 22j. In this embodiment, nitrogen gas, which is the same as the refrigerant gas, is used as the seal gas. However, when air is used as the refrigerant gas, air is also used as the seal gas.

[0092] 7.Effects In the cooling system 10 according to this embodiment, the compressor 21 and the expander 22 are disposed at different positions in the vertical direction. Therefore, in the cooling system 10, the compressor 21 and the expander 22 can be disposed closer to each other than when the compressor and the expander are disposed side by side and on the bottom plate of the casing as in Patent Document 1. That is, in the cold air supply unit of Patent Document 1, the compressor is disposed on one side of the gearbox, and the expander is disposed on the opposite side of the gearbox. Therefore, in the cold air supply unit of Patent Document 1, there is a limit to how close the compressor and the expander can be disposed.

[0093] In contrast, in the cooling system 10 according to this embodiment, the compressor 21 and the expander 22 are arranged at different positions in the vertical direction. Therefore, in the cooling system 10, the compressor 21 and the expander 22 can be arranged closer to each other than in the unit of Patent Document 1, in which the compressor and the expander are arranged horizontally with a gearbox sandwiched between them.

[0094] Furthermore, in the cooling system 10, the compressor 21, which becomes hot during operation of the system, is disposed above the expander 22, which becomes cold during operation, and therefore it is possible to prevent heat generated in the compressor 21 from being transferred to the expander 22. Therefore, in the cooling system 10, it is possible to dispose the compressor 21 and the expander 22 close to each other while preventing thermal problems from occurring between the compressor 21 and the expander 22.

[0095] Furthermore, in the cooling system 10 according to this embodiment, the rotation axes Ax21 and Ax22 of the compressor body 21a and the expander body 22a are arranged so as to be approximately parallel to each other, thereby preventing the arrangement space for the compressor 21 and the expander 22 from becoming unnecessarily large.

[0096] Furthermore, in the cooling system 10 according to this embodiment, the precooler (second heat exchanger) 28 into which high-temperature gas flows is disposed above the brine cooler (first heat exchanger) 23 that constitutes the cooling unit 25. Therefore, in the cooling system 10, it is possible to prevent the heat generated in the precooler 28 from being transferred to the brine cooler 23. Therefore, in the cooling system 10, even if the brine cooler 23 is disposed close to the precooler 28, it is possible to prevent the cooling efficiency of the brine cooler 23 from being reduced due to the heat generated in the precooler 28.

[0097] Furthermore, in the cooling system 10 according to this embodiment, the brine cooler (first heat exchanger) 23 and the precooler (second heat exchanger) 28 are unitized and configured as an integrated cooler unit 29. Therefore, in the cooling system 10, the entire system 10 can be made more compact than when the brine cooler 23 and the precooler 28 are not unitized but provided separately and arranged with a space between them. In other words, if the brine cooler 23 and the precooler 28 were not configured as an integrated unit, frames, brackets, etc. would be needed to fix them to the housing 40, and space would be required for this.

[0098] On the other hand, in this embodiment, the brine cooler 23 and the precooler 28 are unitized (integrated), so there is no need for a frame or bracket for separately arranging the brine cooler 23 and the precooler 28. Therefore, the cooling system 10 is advantageous in that the entire system can be made even more compact.

[0099] Furthermore, in the cooling system 10 according to this embodiment, the aftercooler (third heat exchanger) 27 is disposed vertically above the precooler (second heat exchanger) 28. Therefore, in the cooling system 10, heat transfer from the gas cooler (aftercooler 27) into which high-temperature refrigerant gas flows to the precooler 28 can be suppressed.

[0100] Furthermore, in the cooling system 10 according to this embodiment, the brine tank 22, the brine pump 32, and the heater 34 are arranged below the expander 22 and the brine cooler 23 (cooling section 25), so that the components 32, 33, and 34 of the brine circulation device 14 can be prevented from being affected by heat from the expander 22 and the brine cooler 23.

[0101] In addition, the cooling system 10 according to this embodiment is provided with insulating materials covering the surfaces of the expander 22, the brine cooler 23 (cooling section 25), and the precooler 28, thereby preventing heat from entering these parts 22, 23, and 28 from the outside.

[0102] Furthermore, in the cooling system 10 according to this embodiment, nitrogen gas is used as the refrigerant gas, so that the global warming potential (GWP) can be set to "0".

[0103] As described above, in the cooling system 10 according to this embodiment, the influence of heat between the compressor 21 and the expander 22 can be suppressed.

[0104] [Variation 1] A cooling system 10 according to Modification 1 will be described with reference to Fig. 11. The cooling system 10 according to this modification is different from the first embodiment in that it further includes a fan 60, but other configurations are the same as those of the first embodiment.

[0105] 11, the cooling system 10 according to this modification further includes a fan 60 disposed above the brine circulation device 14. The fan 60 is disposed below the expander 22, and generates an airflow Flow directed upward from a position below the expander 22.

[0106] The cooling system 10 according to this modification has the same configuration as the cooling system 10 of the first embodiment, except that it includes the fan 60 as described above, and therefore can achieve the same effects as the first embodiment.

[0107] Furthermore, the cooling system 10 according to this modification includes the fan 60 that is disposed below the expander 22 and generates an upward airflow Flow, so that the temperature around the compressor 21 can be lowered by the cold heat of the expander 22. Therefore, in the cooling system 10, the compressor 21 can be driven more efficiently.

[0108] [Variation 2] The cooling system 10 according to the second modification will be described with reference to Fig. 12. The cooling system 10 according to this modification is different from the first modification in the location where the fan 60 is disposed, but other configurations are the same as those of the first modification.

[0109] 12, in the cooling system 10 according to this modification, the fan 60 is disposed above the compressor 21. In this modification as well, the fan 60 generates an airflow Flow that flows from the expander 22 toward the compressor 21.

[0110] The cooling system 10 of this modified example also has the same configuration as the cooling system 10 of the first embodiment, as with modified example 1, except that it is equipped with a fan 60, and therefore can achieve the same effects as the first embodiment.

[0111] Furthermore, in the cooling system 10 according to this modification, unlike the first modification, the fan 60 is disposed above the compressor 22, but the airflow Flow still allows the cold heat of the expander 22 to lower the temperature around the compressor 21. Therefore, the cooling system 10 according to this modification can also drive the compressor 21 with higher efficiency.

[0112] [Second embodiment] A cooling system 10 according to a second embodiment will be described with reference to FIG.

[0113] In the first embodiment, the brine cooler 23 provided in the circulation flow path 12 functions as a cooling unit 25 that cools the brine. In contrast, the cooling system 10 according to this embodiment does not include the brine cooler 23 that cools the brine with a refrigerant gas, but instead includes a cooler 50 that functions as the cooling unit 25. Except for the above-mentioned differences, the cooling system 10 according to this embodiment can adopt the same configuration as the first embodiment or the configurations of the above-mentioned modified examples 1 and 2.

[0114] In the cooling system 10 according to this embodiment, the cooler 50 is provided in the low-pressure gas flow path portion 12c of the circulation flow path 12. The cooler 50 is thermally connected to an object to be cooled 500. That is, the cooler 50 cools the object to be cooled 500 by the cold energy of the refrigerant gas.

[0115] Specific examples of the object to be cooled 500 may be a thermal load itself such as a machine or water, or may be a pipe through which a fluid (such as air) for cooling the thermal load flows.

[0116] The cooling system 10 of this embodiment differs from the first embodiment in that it cools the object to be cooled 500 rather than cooling the brine supplied to the demand heat load as described above, but the other configurations are the same, so it can achieve the same effects as the first embodiment.

[0117] [Other variations] The first embodiment, the second embodiment, and the first and second modifications are merely illustrative of the present invention, and it should be understood that the present invention is not limited to the above-described disclosures. Therefore, the present invention allows for various modifications and additions to the configuration, and also allows for appropriate combinations of the above-described disclosures.

[0118] In the first embodiment, the second embodiment, and the first and second modifications, the rotation axis Ax21 of the compressor 21 and the rotation axis Ax22 of the expander 22 are configured to be substantially parallel to each other, but the present invention is not limited to this. The rotation axis Ax21 and the rotation axis Ax22 may be arranged to be at an angle to each other.

[0119] Furthermore, in the first embodiment, the second embodiment, and the first and second modifications, a configuration is adopted in which the precooler 28 is arranged above the brine cooler 23, but in the present invention, it is not essential that the precooler 28 be arranged above the brine cooler 23. For example, it is also possible to employ a configuration in which the vertical positional relationship between the precooler 28 and the brine cooler 23 is reversed, or a configuration in which they are arranged side by side in the horizontal direction.

[0120] Furthermore, in the first embodiment, the second embodiment, and the first and second modifications, the brine cooler 23 and the precooler 28 are unitized as the cooler unit 29, but the present invention is not limited to this. The brine cooler 23 and the precooler 28 may be disposed separately without being unitized.

[0121] Furthermore, in the first embodiment, the second embodiment, and the first and second modifications, a configuration is adopted in which the aftercooler 27 is disposed above the precooler 28, but in the present invention, it is not essential that the aftercooler 27 be disposed above the precooler 28. For example, a configuration in which the vertical positional relationship between the aftercooler 27 and the precooler 28 is reversed, or a configuration in which they are disposed side by side in the horizontal direction, may also be adopted.

[0122] Furthermore, in the first embodiment, the second embodiment, and the first and second modifications, the brine circulation device 14 is arranged below the expander 22 and the brine cooler 23, but the present invention is not limited to this. For example, it is also possible to employ a configuration in which the brine circulation device 14 and the brine cooler 23 are arranged vertically inversely, or arranged side by side in the horizontal direction.

[0123] Furthermore, in the first embodiment, the second embodiment, and the first and second modifications, the components 12, 14, 21, 22, 27, and 29 that make up the cooling system 10 are housed inside a single housing 40, but the present invention is not limited to this. Each of the components 12, 14, 21, 22, 27, and 29 may be arranged separately without the housing 40. [Explanation of symbols]

[0124] 10 Cooling System 12 Reflux channel 12a High-pressure gas flow path 12b Low-pressure gas flow path 14 Brine circulation device 21 Compressor 21a Compressor body 21b Compressor drive unit 21d Motor 22 Expander 22a Expander body 22b Expander driven part 22d Generator 25 Cooling section 27 Aftercooler (gas cooler) 28 Precooler 32 Brine pump 33 Brine Tank 34 Heater 40 cabinets 50 cooler 60 fans 500 cooling object Ax21 Rotation axis Ax22 Rotation axis

Claims

1. A cooling system that cools an object to be cooled using a refrigerant gas, a circulation flow path having a high-pressure gas flow path portion and a low-pressure gas flow path portion, through which the refrigerant gas flows; a screw-type compressor that compresses the refrigerant gas and discharges the refrigerant gas toward the high-pressure gas flow path; a precooler for exchanging heat between the refrigerant gas in the high-pressure gas flow path and the refrigerant gas in the low-pressure gas flow path; a screw-type expander that expands the refrigerant gas from the high-pressure gas flow path portion cooled by the precooler and flows the refrigerant gas into the low-pressure gas flow path portion; a cooling section in the low-pressure gas flow path section that cools an object to be cooled using cold energy of the refrigerant gas flowing out from the expander; Equipped with The compressor is a compressor body having a screw rotor; a compressor drive unit having a motor and driving the screw rotor in the compressor body; Equipped with The expander is an expander body having a screw rotor; an expander driven unit having a generator and driven by the screw rotor in the expander body; Equipped with A refrigeration system wherein the compressor is disposed above the expander.

2. The cooling system according to claim 1 , wherein the compressor and the expander are arranged such that a rotation axis of the compressor body and a rotation axis of the expander body are substantially parallel to each other.

3. the cooling unit is composed of a first heat exchanger, the precooler is comprised of a second heat exchanger; The cooling system according to claim 1 or 2, wherein the second heat exchanger is disposed above the first heat exchanger.

4. The cooling system according to claim 3 , wherein the first heat exchanger and the second heat exchanger are integrally configured.

5. a gas cooler provided in the high-pressure gas flow path between the compressor and the precooler and configured to cool the refrigerant gas in the high-pressure gas flow path from the compressor to the precooler; the gas cooler is composed of a third heat exchanger; The cooling system of claim 3 , wherein the third heat exchanger is disposed above the second heat exchanger.

6. the object to be cooled is brine, The system further includes a brine circulation device that circulates the brine between the cooling unit and a demand-side heat load, The brine circulation device is a brine tank for storing the brine; a brine pump for circulating the brine; a heater that adjusts the temperature of the brine that flows into the demand-side heat load; Equipped with The cooling system according to claim 3 , wherein the brine tank, the brine pump, and the heater in the brine circulation device are disposed below the expander and the cooling section.

7. The cooling system according to claim 3 , further comprising a heat insulating material covering the surfaces of the expander, the cooling section, and the precooler.

8. The cooling system of claim 1 , wherein the refrigerant gas is nitrogen gas.

9. The cooling system according to claim 1 , further comprising a fan that generates an airflow from below to above the expander.

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