Cooling device, and method for operating cooling device

Abstract

A cooling device for cooling a cooling chamber of a refrigeration container, said cooling device comprising: a turbine for expanding air drawn in from the cooling chamber; and a control device for controlling the operation of the turbine, wherein the control device includes a start-up operation unit that, when the cooling device is started, operates the turbine at a first rotation speed until the inlet temperature of the turbine drops below a preset inlet-side prescribed temperature, and, when the inlet temperature of the turbine is lower than the inlet-side prescribed temperature, operates the turbine at a second rotation speed greater than the first rotation speed.

Description

Cooling device and method for operating the cooling device

[0001] This disclosure relates to a cooling device for cooling a cooling chamber of a refrigerated container and a method of operating the cooling device.This application claims priority to Japanese Patent Application No. 2023-200691, filed with the Japan Patent Office on November 28, 2023, the contents of which are incorporated herein by reference.

[0002] For example, Patent Document 1 discloses a cooling device that uses an air refrigerant cycle (a system in which air drawn into a cooling chamber is cooled and the cooled air is sent out to the cooling chamber). This cooling device includes a turbine that expands and cools the air drawn into the cooling chamber.

[0003] Patent No. 3891668

[0004] When starting a cooling device, if the turbine rotation speed is suddenly increased, there is a risk that moisture contained in the air drawn in from the cooling chamber will freeze inside the turbine. Ice buildup inside the turbine reduces the flow rate of air circulating through the turbine, resulting in a decline in the performance of the cooling device. In the cooling device described in Patent Document 1, the ice builder is installed closer to the air outlet than the expander (turbine), so there is a risk of ice buildup inside the turbine when the cooling device is started. Furthermore, unlike freezers with large-capacity cooling chambers (e.g., large refrigerated warehouses), the size of the cooling device installed in a refrigerated container is limited, so it is desirable to suppress the size of the cooling device.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a cooling device and an operating method for the cooling device that can suppress performance degradation due to icing inside the turbine when started up while suppressing an increase in size.

[0006] In order to achieve the above object, the cooling device according to the present disclosure is a cooling device for cooling a cooling chamber of a refrigerated container, and includes a turbine that expands air drawn in from the cooling chamber, and a control device that controls operation of the turbine, wherein the control device includes a startup operation unit that, when the cooling device is started, operates the turbine at a first rotation speed until an inlet temperature of the turbine falls below a predetermined inlet side specified temperature, and operates the turbine at a second rotation speed higher than the first rotation speed when the inlet temperature of the turbine is below the inlet side specified temperature.

[0007] In order to achieve the above object, the cooling device according to the present disclosure is a cooling device for cooling a cooling chamber of a refrigerated container, and includes a turbine that expands air drawn in from the cooling chamber, and a control device that controls operation of the turbine, wherein the control device includes a startup operation unit that, when the cooling device is started, operates the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature, and operates the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature.

[0008] In order to achieve the above object, a cooling device according to the present disclosure is a cooling device for cooling a cooling chamber of a refrigerated container, and includes a turbine that expands air drawn in from the cooling chamber, and a control device that controls operation of the turbine, wherein the control device includes a startup operation unit that, when the cooling device is started, operates the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature, operates the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature, operates the turbine at the second rotation speed until an inlet temperature of the turbine falls below a predetermined inlet-side specified temperature, and operates the turbine at a third rotation speed higher than the second rotation speed when the inlet temperature of the turbine is below the inlet-side specified temperature.

[0009] In order to achieve the above object, a method of operating a cooling device according to the present disclosure is a method of operating a cooling device for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, the method including the steps of, when the cooling device is started, operating the turbine at a first rotation speed until an inlet temperature of the turbine falls below a predetermined inlet side specified temperature, and operating the turbine at a second rotation speed higher than the first rotation speed when the inlet temperature of the turbine is below the inlet side specified temperature.

[0010] In order to achieve the above object, a method of operating a cooling device according to the present disclosure is a method of operating a cooling device for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, the method comprising the steps of, when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature, and operating the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature.

[0011] In order to achieve the above object, a method of operating a cooling device according to the present disclosure is a method of operating a cooling device for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, the method comprising the steps of, when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature, operating the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature, operating the turbine at the second rotation speed until an inlet temperature of the turbine falls below a predetermined inlet-side specified temperature, and operating the turbine at a third rotation speed higher than the second rotation speed when the inlet temperature of the turbine is below the inlet-side specified temperature.

[0012] According to the cooling device and the method of operating the cooling device of the present disclosure, it is possible to suppress performance degradation due to icing inside the turbine when started up while suppressing an increase in size.

[0013] FIG. 1 is a diagram schematically showing an example of the configuration of a refrigerated container. FIG. 2 is a diagram schematically showing the configuration of a cooling device according to a first embodiment. FIG. 3 is a schematic functional block diagram of a control device according to a first embodiment. FIG. 4 is a diagram schematically showing the configuration of a cooling device according to a second embodiment. FIG. 5 is a schematic functional block diagram of a control device according to a second embodiment. FIG. 6 is a diagram schematically showing the configuration of a cooling device according to a third embodiment. FIG. 7 is a schematic functional block diagram of a control device according to a third embodiment. FIG. 8 is a diagram schematically showing the configuration of a turbine according to an embodiment. FIG. 9 is a diagram for explaining "having water repellency" in the present disclosure. FIG. 10 is a perspective view showing an enlarged view of a part of a scroll flow passage forming section according to an embodiment. FIG. 11 is a perspective view showing an enlarged view of a part of a nozzle flow passage forming section according to an embodiment. FIG. 12 is a diagram schematically showing the internal configuration of a turbine according to an embodiment. FIG. 13 is a flowchart showing a method of operating a cooling device according to an embodiment. FIG. 14 is a flowchart showing a method of operating a cooling device according to another embodiment. FIG. 15 is a flowchart showing a method of operating a cooling device according to yet another embodiment.

[0014] Hereinafter, a cooling device and an operating method of a cooling device according to an embodiment of the present disclosure will be described with reference to the drawings. The embodiment shows one aspect of the present disclosure, but does not limit the present disclosure and can be modified as desired within the scope of the technical concept of the present disclosure.

[0015] The cooling device according to the present disclosure cools the cooling chamber of a refrigerated container. This cooling device employs a system (air refrigerant cycle) in which air is extracted from the cooling chamber, cooled, and then sent back to the cooling chamber.

[0016] Fig. 1 is a diagram schematically illustrating an example of the configuration of a refrigerated container 100. As illustrated in Fig. 1, the refrigerated container 100 includes a main body 102 and a cooling device 1 according to the present disclosure.

[0017] The main body 102 has a rectangular cylindrical shape and includes an upper wall, a lower wall, a left wall, a right wall, and a rear wall, and is open at the front. The cooling device 1 is fitted into the front of the main body 102. The interior of the main body 102 is defined as a cooling chamber 101 by being surrounded by the upper wall, the lower wall, the left wall, the right wall, the rear wall, and the cooling device 1. Although not shown, the cooling chamber 101 may be provided with an openable door on at least one of the left wall, the right wall, and the rear wall so that workers can enter and exit the cooling chamber 101. Note that in some embodiments, the main body 102 includes a front wall, and the cooling device 1 is fitted into the front wall.

[0018] As described above, the cooling device 1 employs an air refrigerant cycle, in which air drawn in from the cooling chamber 101 (hereinafter referred to as drawn air A2) is cooled by the turbine 2 (expansion turbine) to generate cooled air A1, and this cooled air A1 is sent to the cooling chamber 101. In the embodiment illustrated in FIG. 1 , the cooling device 1 is configured to be able to maintain the temperature of the cooling chamber 101 in a range of −40° C. or higher and lower than 20° C. In other words, the refrigerated container 100 illustrated in FIG. 1 is a low-temperature container (a so-called reefer container). In some embodiments, the refrigerated container 100 is an ultra-low temperature container or a cryogenic container that is able to maintain the temperature inside the cooling chamber 101 below −40° C.

[0019] <Cooling Device> (Configuration) The configuration of the cooling device 1A (1) according to the first embodiment will be described. Fig. 2 is a diagram schematically showing the configuration of the cooling device 1A according to the first embodiment. As shown in Fig. 2, the cooling device 1A includes a turbine 2 and a control device 4. In the embodiment illustrated in Fig. 2, the cooling device 1A further includes an air line 6, a heat exchanger 8, a compressor 10, and an air cooler 12.

[0020] The air line 6 is formed of, for example, piping or ducts, and has a flow path formed therein that starts from drawing in the suction air A2 from the cooling chamber 101 and ends with sending out cooled air A1 obtained by cooling the suction air A2 to the cooling chamber 101. The air line 6 is provided with a heat exchanger 8, a compressor 10, an air cooler 12, and a turbine 2. In the flow direction of the suction air A2 through the air line 6, the suction air A2 flows through the heat exchanger 8, compressor 10, air cooler 12, heat exchanger 8, and turbine 2 in this order from the upstream side.

[0021] The heat exchanger 8 uses the suction air A2 immediately after being sucked from the cooling chamber 101 as a refrigerant via a heat transfer wall (not shown) to cool the suction air A2 compressed by the compressor 10. The suction air A2 cooled by the heat exchanger 8 is supplied to the turbine 2. The suction air A2 used as a refrigerant is brought to room temperature (15 to 30 degrees) and supplied to the compressor 10.

[0022] The compressor 10 compresses the intake air A2 that has been brought to room temperature by the heat exchanger 8, thereby increasing the temperature and pressure of the intake air A2. In the embodiment illustrated in Fig. 2, the cooling device 1 further includes a motor 14 and a pair of drive shafts 15a, 15b extending coaxially from the motor 14. The compressor 10 is connected to the motor 14 by one drive shaft 15a and is driven by the motor 14. Furthermore, power generated by the turbine 2 is transmitted to the compressor 10 via the pair of drive shafts 15a, 15b, and the power of the turbine 2 can be used as auxiliary power for driving the compressor 10.

[0023] The air cooler 12 cools (pre-cools) the intake air A2 that has been heated to a high temperature and pressurized by the compressor 10. The air cooler 12 is, for example, a fin-tube heat exchanger and includes a cooling water flow path through which cooling water flows. The air cooler 12 exchanges heat between the high-temperature and high-pressure intake air A2 and the cooling water, and cools the intake air A2 to approximately room temperature. The air cooler 12 may have any configuration as long as it can cool the intake air A2 to approximately room temperature. For example, the air cooler 12 may cool the high-temperature and high-pressure intake air A2 to approximately room temperature using cooling air instead of cooling water.

[0024] The intake air A2 cooled to about room temperature by the air cooler 12 is supplied to the heat exchanger 8. The heat exchanger 8 then exchanges heat between the intake air A2 at about room temperature and the intake air A2 immediately after being sucked in from the cooling chamber 101 (the intake air A2 cooled to about room temperature by the air cooler 12 is pre-cooled).

[0025] The turbine 2 expands the intake air A2 pre-cooled by the heat exchanger 8 to reduce the temperature and pressure of the intake air A2 (to generate cooled air A1). The turbine 2 is connected to the motor 14 by the other drive shaft 15b and is driven by the motor 14. The cooled air A1 generated by the turbine 2 flows through the air line 6 and is sent to the cooling chamber 101. The turbine 2 operates at a rotation speed corresponding to the rotation speed of the motor 14. In the present disclosure, the description will be given assuming that the rotation speed of the turbine 2 and the rotation speed of the motor 14 are equal.

[0026] The control device 4 controls the operation of the turbine 2. In one embodiment, the control device 4 is electrically connected to the motor 14 and controls the rotation speed of the turbine 2 via the motor 14. The control device 4 is a computer such as an electronic control device, and includes, for example, a processor such as a CPU or GPU (not shown), memories such as ROM and RAM, and an I / O interface. The processor of the control device 4 operates (calculates, etc.) according to instructions of a program loaded into the memory, thereby realizing each functional unit of the control device 4. Each functional unit of the control device 4 according to the first embodiment will be described with reference to FIG. 3 . In some embodiments, the control device 4 is a cloud server provided in a cloud environment.

[0027] Fig. 3 is a schematic functional block diagram of the control device 4 according to the first embodiment. As shown in Fig. 3, the control device 4 includes a startup operation unit 20A.

[0028] In the first embodiment, as illustrated in FIG. 2 , the cooling device 1A further includes an inlet temperature sensor 16 that measures an inlet temperature T1 of the turbine 2. The control device 4 is electrically connected to the inlet temperature sensor 16 and acquires the inlet temperature T1. When the cooling device 1A is started, the startup operation unit 20A operates the turbine 2 at a first rotation speed X1 until the inlet temperature T1 of the turbine 2 falls below a predetermined inlet-side specified temperature TA. Then, when the inlet temperature T1 of the turbine 2 is below the inlet-side specified temperature TA, the startup operation unit 20A operates the turbine 2 at a second rotation speed X2 that is higher than the first rotation speed X1. The startup operation unit 20A is capable of detecting the start-up of the cooling device 1A, for example, by detecting that a power source (not shown) has been turned on.

[0029] The operation of the startup operation unit 20A will be described in detail. When the cooling device 1A starts, the startup operation unit 20A instructs the motor 14 to rotate at the first rotation speed X1. When the motor 14 receives an instruction PA including the first rotation speed X1 from the startup operation unit 20A, it rotates at the first rotation speed X1. The turbine 2 also operates at the first rotation speed X1, and the cooling chamber 101 is gradually cooled. When the inlet temperature T1 becomes lower than the specified inlet temperature TA, the startup operation unit 20A instructs the motor 14 to rotate at the second rotation speed X2. When the motor 14 receives an instruction PA including the second rotation speed X2 from the startup operation unit 20A, it rotates at the second rotation speed X2. The turbine 2 also operates at the second rotation speed X2, and the cooling chamber 101 is further cooled. In the first embodiment, the second rotation speed X2 is, for example, the rated rotation speed of the turbine 2. The first rotation speed X1 is a low rotation speed that does not freeze the moisture contained in the intake air A2 supplied to the turbine 2. The specified inlet temperature TA is a temperature between −5° C. and 10° C., for example, 0° C.

[0030] (Operation and Effect) The air in the cooling chamber 101 before the cooling device 1 is started may contain moisture. Therefore, if the rotation speed of the turbine 2 is suddenly increased when the cooling device 1 is started, there is a risk that the moisture contained in the air sucked in from the cooling chamber 101 (suction air A2) will freeze inside the turbine 2. If icing occurs inside the turbine 2, the flow rate of the intake air A2 circulating inside the turbine 2 will decrease, resulting in a deterioration in the performance of the cooling device 1.

[0031] According to the first embodiment, when the cooling device 1A is started, the turbine 2 operates at the first rotation speed X1 until the inlet temperature T1 falls below the specified inlet temperature TA. Once the inlet temperature T1 is below the specified inlet temperature TA, the turbine 2 operates at the second rotation speed X2. Therefore, even if moisture contained in the intake air A2 condenses and droplets form inside the turbine 2 while the turbine 2 is operating at the first rotation speed X1, these droplets can be disposed of as needed before they freeze. After the intake air A2 is dehydrated, the turbine 2 is operated at the second rotation speed X2 (the rated operating speed). This prevents icing from forming inside the turbine 2. This prevents performance degradation of the cooling device 1A due to icing inside the turbine 2 during startup.

[0032] Incidentally, one method for treating the droplets is to guide them by suction air A2 or cooling air A1 downstream of a nozzle flow path 25 (described later) of the turbine 2 or to the cooling chamber 101, where they are frozen. In some embodiments, the cooling device 1A includes an icer that is provided downstream of the turbine 2 in the air line 6 and that freezes moisture contained in the cooling air A1. In some embodiments, the turbine 2 is configured to drain droplets formed within the turbine 2.

[0033] Furthermore, according to the first embodiment, icing inside the turbine 2 is suppressed by controlling the operation of the turbine 2, and no new device for suppressing icing is added. Therefore, it is possible to suppress an increase in size of the cooling system 1A, while suppressing a decrease in performance due to icing inside the turbine 2 when the cooling system 1A is started. In particular, the refrigerated container 100 limits the size of the cooling system 1A, so the cooling system 1A according to the present disclosure is advantageous.

[0034] Furthermore, the cooling device 1A illustrated in FIG. 2 can cool the cooling chamber 101 more quickly than the cooling device 1C described later.

[0035] <Cooling Device> (Configuration) A cooling device 1B(1) according to a second embodiment will be described. FIG. 4 is a diagram that schematically shows the configuration of the cooling device 1B according to the second embodiment. FIG. 5 is a schematic functional block diagram of a control device 4 according to the second embodiment. The cooling device 1B according to the second embodiment differs from the cooling device 1A according to the first embodiment described above in that the operation of the turbine 2 is controlled based on the outlet temperature T2 of the turbine 2. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0036] In the second embodiment, as illustrated in FIG. 4 , the cooling device 1B includes an outlet temperature sensor 17 that measures an outlet temperature T2 of the turbine 2. The control device 4 is electrically connected to the outlet temperature sensor 17 and acquires the outlet temperature T2. As illustrated in FIG. 5 , the control device 4 includes a startup operation unit 20B. When the cooling device 1 is started, the startup operation unit 20B operates the turbine 2 at a first rotation speed X1 until the outlet temperature T2 falls below a predetermined outlet-side specified temperature TB, and operates the turbine 2 at a second rotation speed X2 when the outlet temperature T2 is below the outlet-side specified temperature TB. The startup operation unit 20B is capable of detecting the start-up of the cooling device 1B, for example, by detecting that a power source (not shown) has been turned on.

[0037] The operation of the startup operation unit 20B will be described in detail. When the cooling device 1A starts, the startup operation unit 20B instructs the motor 14 to rotate at the first rotation speed X1. When the motor 14 receives an instruction PB including the first rotation speed X1 from the startup operation unit 20B, it rotates at the first rotation speed X1. The turbine 2 also operates at the first rotation speed X1, and the cooling chamber 101 is gradually cooled. When the outlet temperature T2 becomes lower than the specified outlet temperature TB, the startup operation unit 20B instructs the motor 14 to rotate at the second rotation speed X2. When the motor 14 receives an instruction PB including the second rotation speed X2 from the startup operation unit 20B, it rotates at the second rotation speed X2. The turbine 2 also operates at the second rotation speed X2, and the cooling chamber 101 is further cooled. In the second embodiment, the second rotation speed X2 is, for example, the rated rotation speed of the turbine 2. The first rotation speed X1 is a low rotation speed that does not freeze the moisture contained in the intake air A2 supplied to the turbine 2. The specified outlet temperature TB is a temperature between −5° C. and 10° C., for example, 0° C.

[0038] (Operations and Effects) According to the second embodiment, when the cooling device 1B is started, the turbine 2 operates at the first rotation speed X1 until the outlet temperature T2 falls below the specified outlet temperature TB. Once the outlet temperature T2 is below the specified outlet temperature TB, the turbine 2 operates at the second rotation speed X2. Therefore, even if moisture contained in the intake air A2 condenses and droplets form inside the turbine 2 while the turbine 2 is operating at the first rotation speed X1, these droplets can be disposed of as desired before freezing. After the intake air A2 is dehydrated, the turbine 2 is operated at the second rotation speed X2 (rated operating speed). This prevents icing from occurring inside the turbine 2. This prevents performance degradation of the cooling device 1B due to icing inside the turbine 2 during startup. A specific example of a method for disposing of droplets has been described above.

[0039] Furthermore, according to the cooling system 1B illustrated in Fig. 4, icing inside the turbine 2 is suppressed by controlling the operation of the turbine 2, and no new device for suppressing icing is added. Therefore, it is possible to suppress an increase in size of the cooling system 1B, while suppressing a decrease in performance due to icing inside the turbine 2 when the cooling system 1B is started. In particular, the cooling system 1B according to the present disclosure is advantageous because the refrigerated container 100 limits the size of the cooling system 1B.

[0040] Furthermore, the cooling device 1B illustrated in FIG. 4 can cool the cooling chamber 101 more quickly than the cooling device 1C described later.

[0041] <Cooling Device> (Configuration) A cooling device 1C (1) according to a third embodiment will be described. FIG. 6 is a diagram schematically showing the configuration of the cooling device 1C according to the third embodiment. FIG. 7 is a schematic functional block diagram of a control device 4 according to the third embodiment. The cooling device 1C according to the third embodiment differs from the cooling device 1A according to the first embodiment and the cooling device 1B according to the second embodiment in that the operation of the turbine 2 is controlled based on the inlet temperature T1 of the turbine 2 and the outlet temperature T2 of the turbine 2. In the third embodiment, the same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0042] In the third embodiment, as illustrated in FIG. 6 , the cooling device 1C includes an inlet temperature sensor 16 and an outlet temperature sensor 17. The control device 4 is electrically connected to the inlet temperature sensor 16 and the outlet temperature sensor 17, respectively, and acquires the inlet temperature T1 and the outlet temperature T2. As illustrated in FIG. 7 , the control device 4 includes a startup operation unit 20C. When the cooling device 1C is started, the startup operation unit 20C operates the turbine 2 at a first rotation speed X1 until the outlet temperature T2 falls below a specified outlet temperature TB. If the outlet temperature T2 is below the specified outlet temperature TB, the startup operation unit 20C operates the turbine 2 at a second rotation speed X2. If the inlet temperature T1 falls below the specified inlet temperature TA, the startup operation unit 20C operates the turbine 2 at the second rotation speed X2. If the inlet temperature T1 is below the specified inlet temperature TA, the startup operation unit 20C operates the turbine at a third rotation speed X3 greater than the second rotation speed X2. The startup operation unit 20C is capable of detecting the startup of the cooling device 1C, for example, by detecting that a power supply (not shown) has been turned on.

[0043] The operation of the startup operation unit 20C will be described in detail. When the cooling device 1A starts, the startup operation unit 20C instructs the motor 14 to rotate at the first rotation speed X1. When the motor 14 receives an instruction PC including the first rotation speed X1 from the startup operation unit 20C, it rotates at the first rotation speed X1. The turbine 2 also operates at the first rotation speed X1, and the cooling chamber 101 is gradually cooled. When the outlet temperature T2 falls below the specified outlet temperature TB, the startup operation unit 20C instructs the motor 14 to rotate at the second rotation speed X2. When the motor 14 receives an instruction PC including the second rotation speed X2 from the startup operation unit 20C, it rotates at the second rotation speed X2. The turbine 2 also operates at the second rotation speed X2, and the cooling chamber 101 is further cooled. The startup operation unit 20C maintains the turbine 2 operating at the second rotation speed X2 until the inlet temperature T1 falls below the specified inlet temperature TA. When the inlet temperature T1 falls below the specified inlet temperature TA, the startup operation unit 20C instructs the motor 14 to rotate at the third rotation speed X3. When the motor 14 receives the instruction PC including the third rotation speed X3 from the startup operation unit 20C, the motor 14 rotates at the third rotation speed X3. The turbine 2 is also operated at the third rotation speed X3, and the cooling chamber 101 is further cooled.

[0044] In the third embodiment, the third rotation speed X3 is, for example, the rated rotation speed of the turbine 2. The first rotation speed X1 is a low rotation speed at which moisture contained in the intake air A2 supplied to the turbine 2 does not freeze. The second rotation speed X2 is a medium rotation speed that is lower than the third rotation speed X3 and higher than the first rotation speed X1. The specified inlet temperature TA is a temperature not lower than -5 degrees and not higher than 10 degrees, for example, 0 degrees. The specified outlet temperature TB is a temperature not lower than -5 degrees and not higher than 10 degrees, for example, 0 degrees.

[0045] (Operations and Effects) According to the cooling device 1C (third embodiment) illustrated in FIG. 6 , when the cooling device 1C is started, the turbine 2 operates at the first rotation speed X1 until the outlet temperature T2 falls below the specified outlet temperature TB. If the outlet temperature T2 is below the specified outlet temperature TB, the turbine 2 operates at the second rotation speed X2. Furthermore, the turbine 2 maintains operation at the second rotation speed X2 until the inlet temperature T1 falls below the specified inlet temperature TA. If the inlet temperature T1 is below the specified inlet temperature TA, the turbine 2 operates at the third rotation speed X3. Therefore, even if moisture contained in the intake air A2 condenses and droplets form inside the turbine 2 while the turbine 2 is operating at the first rotation speed X1 or the second rotation speed X2, these droplets can be disposed of before freezing. After the intake air A2 is dehydrated, the turbine 2 is operated at the third rotation speed X3 (rated operating speed). This suppresses icing inside the turbine 2. Therefore, it is possible to suppress a decrease in performance of the cooling device 1C due to icing inside the turbine 2 when the cooling device 1C is started up. Note that a specific example of the method for treating the droplets has been described above.

[0046] 6, icing inside the turbine 2 is suppressed by controlling the operation of the turbine 2, and no additional device for suppressing icing is required. This prevents the cooling system 1C from becoming too large, while also suppressing performance degradation due to icing inside the turbine 2 when the cooling system 1C is started. In particular, the cooling system 1C according to the present disclosure is advantageous because the refrigerated container 100 limits the size of the cooling system 1C.

[0047] 6, the turbine 2 is operated at three speeds (low, medium, and high) from the first rotation speed X1 to the third rotation speed X3 according to the outlet temperature T2 and the inlet temperature T1. Therefore, compared with the cooling device 1A according to the first embodiment and the cooling device 1B according to the second embodiment, the amount of droplets formed by condensation of moisture contained in the intake air A2 can be increased. In other words, performance degradation due to icing inside the turbine 2 during startup can be further suppressed.

[0048] <Turbine> (Configuration) An example of a specific configuration of the turbine 2 will be described. Fig. 8 is a diagram schematically illustrating the configuration of the turbine 2 according to one embodiment. As illustrated in Fig. 8, the turbine 2 includes a turbine rotor 22, a scroll passage forming section 24 that forms a scroll passage 23 on the outer circumferential side of the turbine rotor 22, and a nozzle passage forming section 26 that forms a nozzle passage 25 for guiding the suction air A2 from the scroll passage 23 to the turbine rotor 22.

[0049] 8, the turbine 2 includes a casing 21 that rotatably houses a turbine rotor 22. The casing 21 has a scroll passage forming portion 24, a nozzle passage forming portion 26, and an exhaust passage forming portion 44. The turbine rotor 22 includes a plurality of rotor blades 35 that rotate when receiving the flow of suction air A2. The turbine rotor 22 is connected to a drive shaft 15b.

[0050] In the following description, the direction in which the axis O of the turbine rotor 22 extends is referred to as the axial direction D1, the drive shaft 15b side of the axial direction D1 is referred to as the rear end side of the axial direction D1, and the side opposite the rear end side is referred to as the front end side of the axial direction D1. The direction perpendicular to the axis O is referred to as the radial direction D2, the direction in the radial direction D2 that approaches the axis O is referred to as the inner side of the radial direction D2, and the direction that moves away from the axis O is referred to as the outer side of the radial direction D2.

[0051] The scroll passage forming portion 24 has a scroll passage surface 30, which is a surface facing the scroll passage 23. The scroll passage 23 is a spiral passage for guiding the intake air A2 flowing into the turbine 2 to the turbine rotor 22. The scroll passage 23 extends along a circumferential direction D3 about the axis O, outside the turbine rotor 22 in the radial direction D2 (on the outer periphery of the turbine rotor 22).

[0052] The nozzle flow path forming portion 26 has a nozzle flow path surface 32 that is a surface facing the nozzle flow path 25. The nozzle flow path 25 is a flow path for guiding the suction air A2 from the scroll flow path 23 to the turbine rotor 22 that is disposed on the inside of the scroll flow path 23 in the radial direction D2. The nozzle flow path 25 is formed between the scroll flow path 23 and the turbine rotor 22 so as to surround the outside of the turbine rotor 22 in the radial direction D2. The suction air A2 that flows into the turbine 2 flows through the scroll flow path 23 and the nozzle flow path 25 in this order, and is then guided to the turbine rotor 22 from the outside of the turbine rotor 22 in the radial direction D2.

[0053] The exhaust flow passage forming portion 44 has an outlet 46 formed at its tip end in the axial direction D1 for discharging the cooling air A1 from the turbine 2. The exhaust flow passage forming portion 44 has an exhaust flow passage 45 formed therein for sending the suction air A2 (cooling air A1) that has driven the turbine rotor 22 to rotate to the outlet 46.

[0054] In one embodiment, each of the scroll flow passage forming section 24 and the nozzle flow passage forming section 26 has water repellency. FIG. 9 is a diagram for explaining the term "having water repellency" in the present disclosure. As shown in FIG. 9 , in a state in which a droplet 202 of pure water is attached to an object 200 whose water repellency is to be measured (evaluated), let L be the tangent to the surface 203 of the droplet 202 passing through a point P1 where the surface 201 of the object 200 and the surface 203 of the droplet 202 contact each other. The angle formed by the tangent L and the surface 201 of the object 200 on the side where the droplet 202 is present is defined as the contact angle θ. In the present disclosure, "having water repellency" refers to a contact angle θ of 90 degrees or greater. Note that the method for measuring this contact angle θ is not particularly limited, and for example, it may be measured using a contact angle meter (Kyowa Interface Science Co., Ltd., product name: Fully Automatic Contact Angle Meter DMo-902).

[0055] In one embodiment, the scroll flow path forming portion 24 and the nozzle flow path forming portion 26 are each made of an aluminum alloy. In one embodiment, the scroll flow path forming portion 24 has a scroll flow path surface 30 that is water-repellent coated to form a water-repellent layer M. Furthermore, the nozzle flow path forming portion 26 has a nozzle flow path surface 32 that is water-repellent coated to form a water-repellent layer M. The casing 21 has a water-repellent coating applied to the entire surface that faces the flow path through which the suction air A2 flows, to form a water-repellent layer M. In other words, the water-repellent layer M is also formed on the surface of the discharge flow path forming portion 44 that faces the discharge flow path 45.

[0056] FIG. 10 is an enlarged perspective view of a portion of the scroll passage forming section 24 according to one embodiment. In one embodiment, as illustrated in FIG. 10 , the scroll passage forming section 24 has a scroll passage groove 36 formed on the scroll passage surface 30, the scroll passage groove 36 extending along the flow direction Da of the intake air A2 flowing through the scroll passage 23. The scroll passage groove 36 has a width W1 of 0.01 mm or more and 0.5 mm or less. The scroll passage groove 36 is formed to extend at an angle of ±45 degrees or less with respect to the flow direction Da of the intake air A2 flowing through the scroll passage 23. In the embodiment illustrated in FIG. 10 , the scroll passage forming section 24 has a plurality of scroll passage grooves 36 formed on the scroll passage surface 30. The plurality of scroll passage grooves 36 are arranged at intervals along a direction intersecting the flow direction Da of the intake air A2 flowing through the scroll passage 23. When the size of this interval (pitch) is W3, the relationship 0.9×W1<W3<1.1×W1 is satisfied.

[0057] FIG. 11 is an enlarged perspective view of a portion of the nozzle flow channel forming portion 26 according to one embodiment. In one embodiment, as illustrated in FIG. 11 , the nozzle flow channel forming portion 26 has a nozzle flow channel groove 38 formed on the nozzle flow channel surface 32, the nozzle flow channel groove 38 extending along the flow direction Db of the suction air A2 flowing through the nozzle flow channel 25. The nozzle flow channel groove 38 has a width W2 of 0.01 mm or more and 0.5 mm or less. The nozzle flow channel groove 38 is formed to extend at an angle of ±45 degrees or less with respect to the flow direction Db of the suction air A2 flowing through the nozzle flow channel 25. In the embodiment illustrated in FIG. 11 , the nozzle flow channel forming portion 26 has a plurality of nozzle flow channel grooves 38 formed on the nozzle flow channel surface 32. The plurality of nozzle flow channel grooves 38 are arranged at intervals along a direction intersecting the flow direction Db of the suction air A2 flowing through the nozzle flow channel 25. If the size of this interval (pitch) is W4, the relationship 0.9×W2<W4<1.1×W4 is satisfied.

[0058] Fig. 12 is a diagram schematically illustrating an internal configuration of a turbine 2 according to one embodiment, as viewed from the tip side in the axial direction D1. In one embodiment, as illustrated in Fig. 12 , the turbine 2 further includes a plurality of nozzle vanes 40 arranged in the nozzle flow path 25 at intervals in the circumferential direction D3. The nozzle vanes 40 have a surface 42 facing the nozzle flow path 25 that is subjected to a water-repellent coating treatment, and a water-repellent layer M is formed thereon. However, the nozzle vanes 40 do not have groove processing that forms grooves on the surface 42 facing the nozzle flow path 25. In one embodiment, the number of nozzle vanes 40 is smaller than the number of rotor blades 35.

[0059] (Functions and Effects) Of the flow paths through which the suction air A2 flows, the nozzle flow path 25 has a relatively narrow flow path cross-section, and is therefore significantly affected when droplets freeze. For this reason, it is desirable to actively suppress icing in the nozzle flow path 25. The discharge flow path 45 has a flow path cross-section larger than that of the nozzle flow path 25. Therefore, in the turbine 2 according to one embodiment, since the scroll flow path forming portion 24 and the nozzle flow path forming portion 26 are each water-repellent, even if moisture contained in the suction air A2 condenses to form droplets in the scroll flow path 23 or the nozzle flow path 25, the droplets can be guided to the discharge flow path 45, thereby suppressing icing in the nozzle flow path 25.

[0060] In the turbine 2 according to one embodiment, the scroll passage forming portion 24 and the nozzle passage forming portion 26 are each made of an aluminum alloy, which allows the turbine 2 to have water repellency. Note that the present disclosure is not limited to the scroll passage forming portion 24 and the nozzle passage forming portion 26 being made of an aluminum alloy. In some embodiments, one of the scroll passage forming portion 24 and the nozzle passage forming portion 26 is made of an aluminum alloy. The scroll passage forming portion 24 and the nozzle passage forming portion 26 may each be made of a material other than an aluminum alloy and have water repellency.

[0061] In the turbine 2 according to one embodiment, a water-repellent layer M is formed on each of the scroll flow path surface 30 and the nozzle flow path surface 32. This allows each of the scroll flow path surface 30 and the nozzle flow path surface 32 to have water-repellent properties. Note that the present disclosure is not limited to the case where the water-repellent layer M is formed on each of the scroll flow path surface 30 and the nozzle flow path surface 32. In some embodiments, the water-repellent layer M is formed on one of the scroll flow path surface 30 and the nozzle flow path surface 32.

[0062] In the turbine 2 according to one embodiment, the scroll passage forming portion 24 is made of an aluminum alloy, and a water-repellent layer M is formed on the scroll passage surface 30, thereby achieving higher water repellency than when only one of the two is provided. However, the present disclosure is not limited to this configuration. In some embodiments, the scroll passage forming portion 24 is made of an aluminum alloy, but the water-repellent layer M is not formed on the scroll passage surface 30. In some embodiments, the scroll passage forming portion 24 is made of a material that has lower water repellency than the aluminum alloy, and the water-repellent layer M is formed on the scroll passage surface 30. The same applies to the nozzle passage forming portion 26.

[0063] It is generally known that forming grooves on a water-repellent surface can enhance the water-repellency (make the surface super water-repellent). In the turbine 2 according to one embodiment, the scroll flow path surface 30 is formed with scroll flow path grooves 36, and the nozzle flow path surface 32 is formed with nozzle flow path grooves 38. This allows the scroll flow path surface 30 and the nozzle flow path surface 32 to have enhanced water-repellency.

[0064] When the turbine 2 has nozzle vanes 40, forming grooves on the surfaces of the nozzle vanes 40 to increase the water repellency of the nozzle vanes 40 may result in a decrease in performance of the nozzle vanes 40. In the turbine 2 according to one embodiment, the nozzle vanes 40 are not grooved but are subjected to a water repellent coating, and therefore can have water repellency while suppressing a decrease in performance and an increase in manufacturing costs.

[0065] In the turbine 2 according to one embodiment, the number of nozzle vanes 40 is smaller than the number of rotor blades 35. This reduces the number of nozzle vanes 40 to be subjected to the water-repellent coating treatment, thereby reducing manufacturing costs. Furthermore, the total area (wetted edge area) of the nozzle vanes 40 facing the nozzle flow passage 25 can be reduced, further suppressing icing in the nozzle flow passage 25.

[0066] In the turbine 2 according to one embodiment, both the scroll flow path forming portion 24 and the nozzle flow path forming portion 26 are configured to be water-repellent, but the present disclosure is not limited to this configuration. Only the nozzle flow path forming portion 26 may be configured to be water-repellent. In some embodiments, the nozzle flow path forming portion 26 is made of an aluminum alloy, and a nozzle flow path groove 38 having a width of 0.01 mm or more and 0.5 mm or less extending along the flow direction Db of the suction air A2 flowing through the nozzle flow path 25 is formed on the nozzle flow path forming portion 26, and the nozzle flow path surface 32 is subjected to a water-repellent coating treatment. Furthermore, the nozzle vane 40 has a surface facing the nozzle flow path 25 that is subjected to a water-repellent coating treatment, and does not have a groove processing that forms a groove on the surface facing the nozzle flow path 25.

[0067] The nozzle flow passage 25 has a narrower flow passage cross section than the other flow passages formed in the turbine 2. Therefore, it is important to guide the droplets in the nozzle flow passage 25 downstream of the nozzle flow passage 25 and prevent icing in the nozzle flow passage 25. According to the above-described configuration, the nozzle flow passage forming portion 26 is made of an aluminum alloy, and the nozzle flow passage surface 32 is subjected to a water-repellent coating, so that the nozzle flow passage surface 32 has high water repellency. Furthermore, the nozzle vane 40 is not grooved but is subjected to a water-repellent coating, so that it has water repellency while preventing performance degradation and increases in manufacturing costs. Therefore, the droplets in the nozzle flow passage 25 can be guided downstream of the nozzle flow passage 25 and prevent icing in the nozzle flow passage 25.

[0068] <Operation Method of Cooling Device> Figure 13 is a flowchart showing an operation method of the cooling device 1 according to one embodiment. The cooling device 1 includes a turbine 2 that expands air drawn in from the cooling chamber 101 of the refrigerated container 100 to cool the cooling chamber 101. As shown in Figure 13, the operation method of the cooling device 1 according to one embodiment includes a first startup operation step SA in which, when the cooling device 1 is started, the turbine 2 is operated at a first rotation speed X1 until the inlet temperature T1 of the turbine 2 falls below a specified inlet temperature TA (0 degrees), and the turbine is operated at a second rotation speed X2 when the inlet temperature T1 of the turbine 2 is below the specified inlet temperature TA. The operation method of the cooling device 1 according to this embodiment is started when the cooling device 1 is started, and is ended when the turbine 2 is operated at the second rotation speed X2.

[0069] The first startup operation step SA includes a low-speed operation step SA1, an inlet temperature determination step SA2, and a high-speed operation step SA3. In the low-speed operation step SA1, the turbine 2 is operated at a first rotation speed X1. When the cooling device 1 is started, the low-speed operation step SA1 is executed. In the inlet temperature determination step SA2, after the low-speed operation step SA1 is executed, it is determined whether the inlet temperature T1 of the turbine 2 is lower than the specified inlet temperature TA. If the inlet temperature T1 of the turbine 2 is lower than the specified inlet temperature TA (SA2: Yes), the process proceeds to the high-speed operation step SA3. If the inlet temperature T1 of the turbine 2 is equal to or higher than the specified inlet temperature TA (SA2: No), the process returns to the low-speed operation step SA1. In the high-speed operation step SA3, the turbine 2 is operated at a second rotation speed X2. When the high-speed operation step SA3 is executed, the operation method of the cooling device 1 according to one embodiment is terminated.

[0070] Fig. 14 is a flowchart showing an operating method of the cooling system 1 according to another embodiment. The cooling system 1 includes a turbine 2 that expands air drawn in from the cooling chamber 101 of the refrigerated container 100 to cool the cooling chamber 101. As shown in Fig. 14, the operating method of the cooling system 1 according to another embodiment includes a second startup operation step SB in which, when the cooling system 1 is started, the turbine 2 is operated at a first rotation speed X1 until the outlet temperature T2 of the turbine 2 falls below a specified outlet temperature TB (0°C), and the turbine 2 is operated at a second rotation speed X2 when the outlet temperature T2 of the turbine 2 is below the specified outlet temperature TB. The operating method of the cooling system 1 according to this another embodiment is started when the cooling system 1 is started, and is ended when the turbine 2 is operated at the second rotation speed X2.

[0071] The second startup operation step SB includes a low-speed operation step SB1, an outlet temperature determination step SB2, and a high-speed operation step SB3. In the low-speed operation step SB1, the turbine 2 is operated at a first rotation speed X1. When the cooling device 1 is started, the low-speed operation step SB1 is executed. In the outlet temperature determination step SB2, after the execution of the low-speed operation step SB1, it is determined whether the outlet temperature T2 of the turbine 2 is lower than the specified outlet temperature TB. If the outlet temperature T2 of the turbine 2 is lower than the specified outlet temperature TB (SB2: Yes), the process proceeds to the high-speed operation step SB3. If the outlet temperature T2 of the turbine 2 is equal to or higher than the specified outlet temperature TB (SA2: No), the process returns to the low-speed operation step SB1. In the high-speed operation step SB3, the turbine 2 is operated at a second rotation speed X2. When the high-speed operation step SB3 is executed, the operation method of the cooling device 1 according to another embodiment ends.

[0072] Fig. 15 is a flowchart showing an operation method of the cooling system 1 according to yet another embodiment. The cooling system 1 includes a turbine 2 that expands air drawn in from the cooling chamber 101 of the refrigerated container 100 to cool the cooling chamber 101. As shown in Fig. 15, the operation method of the cooling system 1 according to yet another embodiment includes a third startup operation step SC in which, when the cooling system 1 is started, the turbine 2 is operated at a first rotation speed X1 until an outlet temperature T2 of the turbine 2 falls below a specified outlet temperature TB (0°C), the turbine 2 is operated at a second rotation speed X2 when the outlet temperature T2 of the turbine 2 is below the specified outlet temperature TB, the turbine 2 is operated at the second rotation speed X2 until an inlet temperature T1 of the turbine 2 falls below a specified inlet temperature TA (0°C), and the turbine 2 is operated at a third rotation speed X3 when the inlet temperature T1 of the turbine 2 is below the specified inlet temperature TA.

[0073] The third startup operation step SC includes a low-speed operation step SC1, an outlet temperature determination step SC2, a medium-speed operation step SC3, an inlet temperature determination step SC4, and a high-speed operation step SC5. In the low-speed operation step SC1, the turbine 2 is operated at the first rotation speed X1. When the cooling device 1 is started, the low-speed operation step SC1 is executed. In the outlet temperature determination step SC2, after the low-speed operation step SC1 is executed, it is determined whether the outlet temperature T2 of the turbine 2 is lower than the specified outlet temperature TB. If the outlet temperature T2 of the turbine 2 is lower than the specified outlet temperature TB (SC2: Yes), the process proceeds to the medium-speed operation step SC3. If the outlet temperature T2 of the turbine 2 is equal to or higher than the specified outlet temperature TB (SC2: No), the process returns to the low-speed operation step SC1. In the medium-speed operation step SC3, the turbine 2 is operated at the second rotation speed X2. In the inlet temperature determination step SC4, after the medium-speed operation step SC3 is performed, it is determined whether the inlet temperature T1 of the turbine 2 is less than the specified inlet temperature TA. If the inlet temperature T1 of the turbine 2 is less than the specified inlet temperature TA (SC4: Yes), the process proceeds to the high-speed operation step SC5. If the inlet temperature T1 of the turbine 2 is equal to or greater than the specified inlet temperature TA (SC4: No), the process returns to the medium-speed operation step SC3. In the high-speed operation step SC5, the turbine 2 is operated at the third rotation speed X3. When the high-speed operation step SC5 is performed, the method for operating the cooling device 1 according to yet another embodiment is completed.

[0074] The contents described in each of the above embodiments can be understood, for example, as follows.

[0075] [1] A cooling device (1A) according to the present disclosure is a cooling device for cooling a cooling chamber (101) of a refrigerated container (100), and includes a turbine (2) that expands air (A2) drawn in from the cooling chamber, and a control device (4) that controls operation of the turbine, wherein the control device includes a startup operation unit (20A) that, when the cooling device is started, operates the turbine at a first rotation speed (X1) until an inlet temperature (T1) of the turbine falls below a predetermined inlet-side specified temperature (TA), and operates the turbine at a second rotation speed (X2) higher than the first rotation speed when the inlet temperature of the turbine is below the inlet-side specified temperature.

[0076] Before the cooling device is started, the air in the cooling chamber may contain moisture. Therefore, if the turbine rotation speed is suddenly increased when the cooling device is started, the moisture contained in the air drawn in from the cooling chamber may freeze inside the turbine. Ice formation inside the turbine reduces the flow rate of air circulating through the turbine, resulting in a decrease in the performance of the cooling device. According to the configuration described in [1] above, when the cooling device is started, the turbine operates at a first rotation speed until the turbine inlet temperature drops below a specified inlet temperature. If the turbine inlet temperature falls below the specified inlet temperature, the turbine operates at a second rotation speed. Therefore, by appropriately setting the specified inlet temperature, even if the moisture contained in the air drawn in from the cooling chamber condenses and forms droplets, ice formation inside the turbine can be suppressed. Therefore, a decrease in the performance of the cooling device due to ice formation inside the turbine can be suppressed when the cooling device is started.

[0077] Furthermore, according to the configuration described in [1] above, icing inside the turbine is suppressed by controlling the operation of the turbine, and no additional device for suppressing icing is required. This prevents the cooling device from becoming too large and also prevents performance degradation due to icing inside the turbine when the device is started. In particular, the cooling device according to the present disclosure is advantageous because refrigerated containers limit the size of the cooling device.

[0078] [2] A cooling device (1B) according to the present disclosure is a cooling device for cooling a cooling chamber (101) of a refrigerated container (100), and includes a turbine (2) that expands air (A2) drawn in from the cooling chamber, and a control device (4) that controls operation of the turbine, wherein the control device includes a startup operation unit (20B) that, when the cooling device is started, operates the turbine at a first rotation speed (X1) until an outlet temperature (T2) of the turbine falls below a predetermined outlet-side specified temperature (TB), and operates the turbine at a second rotation speed (X2) higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature.

[0079] According to the configuration described in [2] above, when the cooling device is started, the turbine operates at the first rotation speed until the turbine outlet temperature falls below the specified outlet temperature, and then operates at the second rotation speed when the turbine outlet temperature falls below the specified outlet temperature. Therefore, by appropriately setting the specified outlet temperature, even if moisture contained in the air drawn in from the cooling chamber condenses and forms droplets, ice formation inside the turbine can be suppressed. Therefore, degradation of the cooling device's performance due to ice formation inside the turbine can be suppressed when the cooling device is started.

[0080] Furthermore, according to the configuration described in [2] above, icing inside the turbine is suppressed by controlling the operation of the turbine, and no additional device for suppressing icing is required. This prevents the cooling device from becoming too large and also prevents performance degradation due to icing inside the turbine when the device is started. In particular, since refrigerated containers limit the size of cooling devices, the cooling device according to the present disclosure is advantageous.

[0081] [3] A cooling device (1C) according to the present disclosure is a cooling device for cooling a cooling chamber (101) of a refrigerated container (100), comprising: a turbine (2) for expanding air (A2) drawn in from the cooling chamber; and a control device (4) for controlling operation of the turbine, wherein the control device includes a startup operation unit (20C) that, when the cooling device is started, operates the turbine at a first rotation speed (X1) until an outlet temperature (T2) of the turbine falls below a predetermined outlet-side specified temperature (TB), operates the turbine at a second rotation speed (X2) higher than the first rotation speed if the outlet temperature of the turbine is below the outlet-side specified temperature, operates the turbine at the second rotation speed until an inlet temperature (T1) of the turbine falls below a predetermined inlet-side specified temperature (TA), and operates the turbine at a third rotation speed (X3) higher than the second rotation speed if the inlet temperature of the turbine is below the inlet-side specified temperature.

[0082] According to the configuration described in [3] above, when the cooling device is started, the turbine operates at a first rotation speed until the turbine outlet temperature falls below a specified outlet temperature. If the turbine outlet temperature falls below the specified outlet temperature, the turbine operates at a second rotation speed. Furthermore, the turbine operates at a second rotation speed until the turbine inlet temperature falls below the specified inlet temperature. If the turbine inlet temperature falls below the specified inlet temperature, the turbine operates at a third rotation speed. Therefore, by appropriately setting the specified outlet temperature and specified inlet temperature, icing inside the turbine can be suppressed even if moisture contained in the air drawn in from the cooling chamber condenses to form droplets. Therefore, degradation of the cooling device's performance due to icing inside the turbine can be suppressed when the cooling device is started.

[0083] Furthermore, according to the configuration described in [3] above, icing inside the turbine is suppressed by controlling the operation of the turbine, and no additional device for suppressing icing is required. This prevents the cooling device from becoming larger, while also suppressing performance degradation due to icing inside the turbine when it is started. In particular, since refrigerated containers limit the size of cooling devices, the cooling device according to the present disclosure is advantageous.

[0084] Furthermore, according to the configuration described in [3] above, the turbine is operated at three stages from the first rotation speed to the third rotation speed depending on the turbine outlet temperature and inlet temperature, so that the amount of droplets (hereinafter referred to as droplets) formed by condensation of moisture contained in the air sucked in from the cooling chamber can be increased compared to [1] and [2] above.

[0085] [4] In some embodiments, in the configuration described in any one of [1] to [3] above, the turbine includes a turbine rotor (22), a scroll passage forming section (24) that forms a scroll passage (23) on the outer periphery of the turbine rotor, and a nozzle passage forming section (26) that forms a nozzle passage (25) for guiding the air from the scroll passage to the turbine rotor, and each of the scroll passage forming section and the nozzle passage forming section is water-repellent.

[0086] The nozzle flow path has a narrow cross section, and is significantly affected when droplets freeze. For this reason, it is desirable to actively suppress icing in the nozzle flow path. According to the configuration described in [4] above, the scroll flow path forming portion and the nozzle flow path forming portion each have water repellency, so that droplets can be guided to the downstream side of the turbine rather than the nozzle flow path, thereby suppressing icing in the nozzle flow path.

[0087] [5] In some embodiments, in the configuration described in [4] above, the scroll passage forming portion and the nozzle passage forming portion are each made of an aluminum alloy.

[0088] According to the configuration described in [5] above, each of the scroll flow passage forming portion and the nozzle flow passage forming portion can have water repellency.

[0089] [6] In some embodiments, in the configuration described in [4] or [5] above, the scroll flow path forming portion has a surface (30) facing the scroll flow path that is subjected to a water-repellent coating treatment, and the nozzle flow path forming portion has a surface (32) facing the nozzle flow path that is subjected to a water-repellent coating treatment.

[0090] According to the configuration described in [6] above, the surface facing the scroll flow path and the surface facing the nozzle flow path can each have water repellency.

[0091] [7] In some embodiments, in the configuration described in any one of [4] to [6] above, the scroll flow path forming part has a scroll flow path groove (36) formed on a surface facing the scroll flow path, the scroll flow path groove extending along the flow direction (Da) of the air flowing through the scroll flow path, and the scroll flow path groove has a width (W1) of 0.01 mm or more and 0.5 mm or less.

[0092] It is generally known that forming grooves on a water-repellent surface can enhance the water-repellency (make the surface super-water-repellent). According to the configuration described in [7] above, the water-repellency of the surface facing the scroll flow path can be further enhanced.

[0093] [8] In some embodiments, in the configuration described in any one of [4] to [7] above, the nozzle flow path forming portion has a nozzle flow path groove (38) formed on a surface facing the nozzle flow path, the nozzle flow path groove extending along the flow direction (Db) of the air flowing through the nozzle flow path, and the nozzle flow path groove has a width (W2) of 0.01 mm or more and 0.5 mm or less.

[0094] According to the configuration described in [8] above, the water repellency of the surface facing the nozzle flow path can be further improved.

[0095] [9] In some embodiments, in the configuration described in any one of [4] to [8] above, the turbine further includes a plurality of nozzle vanes (40) arranged in the nozzle flow path at intervals in the circumferential direction (D3) of the turbine rotor, and the nozzle vanes are subjected to a water-repellent coating treatment on the surface facing the nozzle flow path, and are not subjected to groove processing to form grooves on the surface facing the nozzle flow path.

[0096] According to the configuration described in [9] above, a turbine having nozzle vanes can be employed. Furthermore, the nozzle vanes are not grooved but are water-repellent coated, so that they can be water-repellent while suppressing performance degradation and increases in manufacturing costs.

[0097]

[10] In some embodiments, in the configuration described in [9] above, the turbine rotor includes a plurality of rotor blades (35), and the number of the plurality of nozzle vanes is less than the number of the rotor blades.

[0098] According to the configuration described in

[10] above, the number of nozzle vanes to be subjected to the water-repellent coating treatment can be reduced, thereby reducing manufacturing costs. Furthermore, the total area (wetted edge area) of the nozzle vanes facing the nozzle flow path can be reduced, thereby further suppressing ice buildup in the nozzle flow path.

[0099]

[11] In some embodiments, in the configuration described in any one of [1] to [3] above, the turbine includes: a turbine rotor; a scroll passage forming section that forms a scroll passage on the outer periphery of the turbine rotor; a nozzle passage forming section that forms a nozzle passage for guiding the air from the scroll passage to the turbine rotor; and a plurality of nozzle vanes that are arranged at intervals in the nozzle passage in the circumferential direction of the turbine rotor, wherein the nozzle passage forming section is made of an aluminum alloy, and the nozzle passage forming section has a nozzle passage groove formed on a surface facing the nozzle passage, the nozzle passage groove having a width of 0.01 mm to 0.5 mm extending along the flow direction of the air circulating through the nozzle passage, and the surface facing the nozzle passage is treated with a water-repellent coating, and the nozzle vane has a surface facing the nozzle passage that is treated with a water-repellent coating, and is not treated with a groove processing that forms a groove on the surface facing the nozzle passage.

[0100] The nozzle flow passage has a narrower flow passage cross section than other flow passages formed in the turbine. Therefore, it is important to guide droplets in the nozzle flow passage downstream of the nozzle flow passage and prevent icing from forming on the nozzle flow passage. According to the configuration described in

[11] above, the nozzle flow passage forming portion is made of an aluminum alloy, and a water-repellent coating is applied to the surface facing the nozzle flow passage, thereby providing high water repellency. Furthermore, the nozzle vane is not grooved but is water-repellent coated, thereby providing water repellency while preventing performance degradation and increases in manufacturing costs. Therefore, droplets in the nozzle flow passage can be guided downstream of the nozzle flow passage and preventing icing from forming on the nozzle flow passage.

[0101]

[12] A method of operating a cooling device according to the present disclosure, for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, includes the steps of: when the cooling device is started, operating the turbine at a first rotation speed until an inlet temperature of the turbine falls below a predetermined inlet-side specified temperature; and operating the turbine at a second rotation speed higher than the first rotation speed when the inlet temperature of the turbine is below the predetermined inlet-side temperature (SA).

[0102] According to the method described in

[12] above, the same effect as that described in [1] above can be achieved.

[0103]

[13] A method of operating a cooling device according to the present disclosure, for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, includes the steps of: when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature; and operating the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature (SB).

[0104] According to the method described in

[13] above, the same effect as that described in [2] above can be achieved.

[0105]

[14] A method of operating a cooling device according to the present disclosure, for cooling a cooling chamber of a refrigerated container, the method of operating a cooling device having a turbine that expands air drawn in from the cooling chamber, includes the steps (SC) of, when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet-side specified temperature, operating the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet-side specified temperature, operating the turbine at the second rotation speed until an inlet temperature of the turbine falls below a predetermined inlet-side specified temperature, and operating the turbine at a third rotation speed higher than the second rotation speed when the inlet temperature of the turbine is below the inlet-side specified temperature.

[0106] According to the method described in

[14] above, the same effect as that described in [3] above can be achieved.

[0107] REFERENCE SIGNS LIST 1 Cooling device 1A Cooling device (first embodiment) 1B Cooling device (second embodiment) 1C Cooling device (third embodiment) 2 Turbine 4 Control device 6 Air line 8 Heat exchanger 10 Compressor 12 Air cooler 14 Motor 15a Drive shaft 15b Drive shaft 16 Inlet temperature sensor 17 Outlet temperature sensor 20A Start-up operation unit (first embodiment) 20B Start-up operation unit (second embodiment) 20C Start-up operation unit (third embodiment) 21 Casing 22 Turbine rotor 23 Scroll passage 24 Scroll passage forming unit 25 Nozzle passage 26 Nozzle passage forming unit 30 Scroll passage surface 32 Nozzle passage surface 35 Rotor blade 36 Scroll passage groove 38 Nozzle passage groove 40 Nozzle vane 42 Nozzle vane surface 45 Exhaust passage 44 Exhaust passage forming unit 46 Outlet 100 Refrigeration container 101 Cooling chamber 102 Main body 200 Object 201 Surface of object 202 Droplet 203 Surface of droplet A1 Cooled air A2 Suction air D1 Axial direction D2 Radial direction D3 Circumferential direction Da Flow direction of suction air (scroll passage) Db Flow direction of suction air (nozzle passage) L Tangent M Water-repellent layer O Axis P1 Point PA Indication (first embodiment) PB Indication (second embodiment) PC Indication (third embodiment) T1 Inlet temperature T2 Outlet temperature TA Inlet-side specified temperature TB Outlet-side specified temperature W1 Width of scroll passage groove W2 Width of nozzle passage groove X1 First rotation speed (low speed) X2 Second rotation speed (medium speed) X3 Third rotation speed (high speed) SA First startup operation step SA1: Low speed operation step SA2: Inlet temperature determination step SA3: High speed operation step SB: Second startup operation step SB1: Low speed operation step SB2: Outlet temperature determination step SB3: High speed operation step SC: Third startup operation step SC1: Low speed operation step SC2: Outlet temperature determination step SC3: Medium speed operation step SC4: Inlet temperature determination step SC5: High speed operation step

Claims

1. A cooling device for cooling a cooling chamber of a refrigerated container, comprising: a turbine that expands air drawn in from the cooling chamber; and a control device that controls operation of the turbine, the control device including a startup operation unit that, when the cooling device is started up, operates the turbine at a first rotation speed until the inlet temperature of the turbine falls below a preset inlet side specified temperature, and operates the turbine at a second rotation speed higher than the first rotation speed when the inlet temperature of the turbine is below the inlet side specified temperature.

2. A cooling device for cooling a cooling chamber of a refrigerated container, comprising: a turbine that expands air drawn in from the cooling chamber; and a control device that controls the operation of the turbine, the control device including a startup operation unit that, when the cooling device is started up, operates the turbine at a first rotation speed until the outlet temperature of the turbine falls below a preset outlet side specified temperature, and operates the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet side specified temperature.

3. A cooling device for cooling a cooling chamber of a refrigerated container, comprising: a turbine that expands air drawn in from the cooling chamber; and a control device that controls operation of the turbine, the control device including a startup operation unit that, when the cooling device is started up, operates the turbine at a first rotation speed until an outlet temperature of the turbine falls below a preset outlet side specified temperature, operates the turbine at a second rotation speed higher than the first rotation speed if the outlet temperature of the turbine is below the outlet side specified temperature, operates the turbine at the second rotation speed until an inlet temperature of the turbine falls below a preset inlet side specified temperature, and operates the turbine at a third rotation speed higher than the second rotation speed if the inlet temperature of the turbine is below the inlet side specified temperature.

4. A cooling device as claimed in any one of claims 1 to 3, wherein the turbine includes a turbine rotor, a scroll flow passage forming section which forms a scroll flow passage on the outer circumferential side of the turbine rotor, and a nozzle flow passage forming section which forms a nozzle flow passage for guiding the air from the scroll flow passage to the turbine rotor, each of the scroll flow passage forming section and the nozzle flow passage forming section being water repellent.

5. The cooling device according to claim 4, wherein the scroll passage forming portion and the nozzle passage forming portion are each made of an aluminum alloy.

6. The cooling device according to claim 4, wherein the scroll flow passage forming portion has a surface facing the scroll flow passage that is treated with a water-repellent coating, and the nozzle flow passage forming portion has a surface facing the nozzle flow passage that is treated with a water-repellent coating.

7. A cooling device as described in claim 4, wherein the scroll passage forming portion has a scroll passage groove formed on a surface facing the scroll passage, the scroll passage groove extending along the flow direction of the air circulating through the scroll passage, and the scroll passage groove has a width of 0.01 mm or more and 0.5 mm or less.

8. A cooling device as described in claim 4, wherein the nozzle flow path forming portion has a nozzle flow path groove formed on a surface facing the nozzle flow path, the nozzle flow path groove extending along the flow direction of the air flowing through the nozzle flow path, and the nozzle flow path groove has a width of 0.01 mm or more and 0.5 mm or less.

9. A cooling device as described in claim 4, wherein the turbine further includes a plurality of nozzle vanes arranged in the nozzle flow passage at intervals in the circumferential direction of the turbine rotor, and the nozzle vanes have a water-repellent coating treatment applied to a surface facing the nozzle flow passage, and the surface facing the nozzle flow passage is not grooved to form a groove.

10. The cooling device according to claim 9, wherein the turbine rotor includes a plurality of rotor blades, and the number of nozzle vanes is less than the number of the rotor blades.

11. The cooling device according to any one of claims 1 to 3, wherein the turbine includes: a turbine rotor; a scroll flow passage forming section which forms a scroll flow passage on the outer circumferential side of the turbine rotor; a nozzle flow passage forming section which forms a nozzle flow passage for guiding the air from the scroll flow passage to the turbine rotor; and a plurality of nozzle vanes which are arranged at intervals in the circumferential direction of the turbine rotor in the nozzle flow passage, wherein the nozzle flow passage forming section is made of an aluminum alloy, wherein the nozzle flow passage forming section has a surface facing the nozzle flow passage formed with a nozzle flow passage groove having a width of 0.01 mm or more and 0.5 mm or less extending along the flow direction of the air flowing through the nozzle flow passage, and wherein the surface facing the nozzle flow passage is treated with a water-repellent coating, and wherein the nozzle vane has a surface facing the nozzle flow passage treated with a water-repellent coating, and wherein the surface facing the nozzle flow passage is not treated with groove processing to form a groove.

12. A method for operating a cooling device for cooling a cooling chamber of a refrigerated container, the method comprising the steps of: when the cooling device is started, operating the turbine at a first rotation speed until an inlet temperature of the turbine falls below a preset inlet side specified temperature; and operating the turbine at a second rotation speed higher than the first rotation speed when the inlet temperature of the turbine is below the inlet side specified temperature.

13. A method for operating a cooling device for cooling a cooling chamber of a refrigerated container, the method comprising the steps of: when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a preset outlet side specified temperature; and operating the turbine at a second rotation speed higher than the first rotation speed when the outlet temperature of the turbine is below the outlet side specified temperature.

14. A method for operating a cooling device for cooling a cooling chamber of a refrigerated container, the method comprising the steps of: when the cooling device is started, operating the turbine at a first rotation speed until an outlet temperature of the turbine falls below a predetermined outlet side specified temperature, operating the turbine at a second rotation speed higher than the first rotation speed if the outlet temperature of the turbine is below the outlet side specified temperature, operating the turbine at the second rotation speed until an inlet temperature of the turbine falls below a predetermined inlet side specified temperature, and operating the turbine at a third rotation speed higher than the second rotation speed if the inlet temperature of the turbine is below the inlet side specified temperature.

Images