JP7608904B2 - Ejector and Cooling System - Google Patents

Description

The present invention relates to an ejector and a cooling system.

Ejectors that mix a suction fluid generated by a driving fluid with the driving fluid and discharge the mixture have been proposed in the past. For example, Patent Document 1 discloses an ejector that ejects high-pressure steam, which is the driving fluid, to suck in low-pressure steam, which is the suction fluid, and mixes and discharges the steam.

International Publication No. 2017/169218

Ejectors are sometimes applied to cooling systems that cool manufacturing machines in factories. In such cooling systems, a cooling fluid such as cooling water or air is used in a condenser that condenses a refrigerant. Here, when the temperature of the cooling fluid rises in a high-temperature environment such as summer, the temperature difference between the refrigerant discharged from the ejector and the cooling fluid becomes smaller, and the amount of heat transferred from the refrigerant to the cooling fluid becomes smaller. As a result, the refrigerant discharged from the ejector becomes less likely to be condensed by the condenser, and the pressure in the flow path connecting the ejector and the condenser increases. When the pressure increases, it becomes more difficult for the refrigerant to be discharged from the ejector, and the flow rate of the suction fluid, which is the refrigerant sucked into the ejector, decreases. Therefore, in a heat exchanger in which the suction fluid cools the cooled medium by heat exchange between the suction fluid and the cooled medium, the flow rate of the suction fluid that cools the cooled medium decreases, resulting in a problem that the ability to continuously cool the cooled medium (hereinafter referred to as operating ability) decreases. In consideration of the above circumstances, one aspect of the present invention aims to suppress the decrease in operating ability in a high-temperature environment.

An ejector according to one aspect of the present invention includes a confluence section where a driving fluid ejected from a nozzle and a suction fluid sucked in with the ejection of the driving fluid join together, a mixing section having a variable mechanism and outputting a mixed fluid in which the driving fluid and the suction fluid are mixed and output from the confluence section, and a diffuser section that pressurizes and discharges the mixed fluid output from the mixing section, and the variable mechanism has a flow path through which the mixed fluid flows and varies the volume of the flow path.

A cooling system according to one aspect of the present invention includes an ejector having a junction where a driving fluid and a suction fluid sucked in with the ejection of the driving fluid join together, a mixing section having a variable mechanism and outputting a mixed fluid obtained by mixing the driving fluid and the suction fluid outputted from the junction, and a diffuser section that pressurizes and discharges the mixed fluid outputted from the mixing section, a steam generator that generates the driving fluid by evaporating a refrigerant through heat exchange with a heat source, and a cooling flow rate that is a mixture of the mixed fluid and the suction fluid discharged from the ejector. The cooling system includes a condenser that converts the mixed fluid into a liquid-phase refrigerant by condensing it through heat exchange between the refrigerant and the medium, a pump that sends a portion of the liquid-phase refrigerant to the vapor generator, an expander that reduces the pressure of the other portion of the liquid-phase refrigerant, and an evaporator that generates the suction fluid by evaporating the reduced pressure refrigerant through heat exchange between the refrigerant reduced pressure by the expander and the medium to be cooled, and supplies the suction fluid to the ejector. The variable mechanism has a flow path through which the mixed fluid flows and varies the volume of the flow path.

FIG. 1 is a diagram illustrating an example of the configuration of a cooling system according to an embodiment. FIG. 2 is a cross-sectional view showing a configuration example of an ejector. FIG. FIG. FIG. 4 is a block diagram illustrating a configuration for controlling a variable mechanism. 4 is a graph showing the relationship between the temperature of a cooling fluid and the ejector efficiency of an ejector. FIG. 11 is a configuration diagram of a cooling system according to a comparative example. FIG. 11 is a cross-sectional view showing a configuration example of an ejector according to a comparative example. FIG. 13 is a perspective view showing a configuration example of an ejector according to a modified example. FIG. 11 is a cross-sectional perspective view of an ejector according to a modified example. FIG. 4 is a perspective view showing an example of the configuration of a plate-shaped portion. 13A and 13B are explanatory diagrams illustrating the operation of a variable mechanism according to a modified example. 13A and 13B are explanatory diagrams illustrating the operation of a variable mechanism according to a modified example.

Below, preferred embodiments of the present invention will be described with reference to the drawings. Note that the dimensions and scale of each part in the drawings may differ from the actual ones as appropriate. Also, the drawings may be shown diagrammatically to facilitate understanding. Furthermore, the scope of the present invention is not limited to the embodiments exemplified below, unless otherwise specified to the effect that the present invention is particularly limited.

1 is a diagram showing an example of the configuration of a cooling system 100 according to an embodiment of the present invention. The cooling system 100 is a system that cools a medium Q3 to be cooled. The medium Q3 to be cooled is a medium to be cooled by the cooling system 100, and is a fluid such as water, oil, or air.

As shown in FIG. 1, the cooling system 100 of this embodiment has a circulation flow path 11, a branch flow path 12, a steam generator 21, an ejector 22, a condenser 24, a pump 25, an expander 31, and an evaporator 32.

In the circulation flow path 11, a steam generator 21, an ejector 22, a condenser 24, and a pump 25 are installed in the above order. The refrigerant in the circulation flow path 11 moves in the order of steam generator 21 → ejector 22 → condenser 24 → pump 25 → steam generator 21. In other words, the circulation flow path 11 is formed by connecting the steam generator 21, the ejector 22, the condenser 24, and the pump 25 in a ring shape. The refrigerant that moves in the circulation flow path 11 is, for example, a fluorocarbon substitute, a hydrocarbon, carbon dioxide, or ammonia.

The steam generator 21 is a heat exchanger (recovery device) that generates a driving fluid X1 by evaporating a refrigerant through heat exchange between hot water Q1 supplied to the hot water flow path 91 as a heat source and the refrigerant in the circulation flow path 11. The hot water Q1 supplied to the hot water flow path 91 is, for example, waste hot water such as industrial wastewater or used cooling water.

The ejector 22 has an inlet 22a, a suction port 22b, and a discharge port 22c. A part of the gas-phase refrigerant discharged from the steam generator 21 is supplied to the inlet 22a as a driving fluid X1. The ejector 22 draws the refrigerant in the branch flow path 12 as a suction fluid Y1 from the suction port 22b due to a drop in static pressure caused by the driving fluid X1. The driving fluid X1 supplied to the inlet 22a and the suction fluid Y1 supplied to the suction port 22b are mixed, and the mixed gas-phase refrigerant is pressurized by a diffuser described later and discharged from the discharge port 22c. As described above, the ejector 22 of this embodiment introduces the refrigerant evaporated in the steam generator 21 as the driving fluid X1 from the inlet 22a, mixes it with the suction fluid Y1 introduced from the suction port 22b, and discharges it from the discharge port 22c. Details of the ejector 22 will be described later.

The condenser 24 condenses the gas-phase refrigerant (mixed fluid, described later) discharged from the ejector 22. Specifically, the condenser 24 condenses the refrigerant through heat exchange between the cooling fluid Q2 supplied to the heat dissipation flow path 92 and the gas-phase refrigerant in the circulation flow path 11, thereby converting the refrigerant into a liquid-phase refrigerant. The cooling fluid Q2 is, for example, low-temperature industrial water or cooling water supplied from a circulating cooling tower. The refrigerant in the circulation flow path 11 condenses by dissipating heat to the cooling fluid Q2. For example, in a high-temperature environment such as summer, the temperature T of the cooling fluid Q2 may rise.

The pump 25 is a liquid-phase pump that sends a portion of the liquid-phase refrigerant condensed by the condenser 24 to the steam generator 21. The pressure of the refrigerant in the circulation flow path 11 is increased by the pump 25 to a pressure at which the ejector 22 can suck in the suction fluid Y1.

The branch flow path 12 is a flow path branched from the circulation flow path 11. That is, another part of the liquid phase refrigerant condensed by the condenser 24 is supplied to the branch flow path 12. Specifically, the branch flow path 12 connects the portion N1 of the circulation flow path 11 between the condenser 24 and the pump 25 to the suction port 22b of the ejector 22. That is, the branch flow path 12 is a flow path that supplies the refrigerant that becomes the suction fluid Y1 to the ejector 22. The portion N1 corresponds to the branch point between the circulation flow path 11 and the branch flow path 12. The branch flow path 12 is a flow path having an expander 31 and an evaporator 32. The evaporator 32 is located between the expander 31 and the suction port 22b of the ejector 22.

The expander 31 is supplied with another portion of the liquid-phase refrigerant condensed by the condenser 24. The expander 31 expands the refrigerant by reducing its pressure. The expander 31 is any type of pressure reduction mechanism, such as an electronic expansion valve, a manual expansion valve, a constant pressure expansion valve, an orifice, or a capillary.

The evaporator 32 is a heat exchanger that generates suction fluid Y1 by evaporating the reduced pressure refrigerant through heat exchange between the cooled medium Q3 supplied to the cooled flow path 93 and a liquid phase medium reduced in pressure by the expander 31. The evaporator 32 is located between the expander 31 and the suction port 22b of the ejector 22. The evaporator 32 supplies the suction fluid Y1 to the suction port 22b of the ejector 22. The refrigerant whose pressure has been reduced by suction from the ejector 22 cools the cooled medium Q3.

Next, the ejector 22 applied to the cooling system 100 will be described in detail. FIG. 2 is a cross-sectional view showing an example of the configuration of the ejector 22, and FIG. 3 is a cross-sectional perspective view of the ejector 22. In the following description, mutually orthogonal X-axis, Y-axis, and Z-axis are assumed. The X-axis, Y-axis, and Z-axis are common to all figures exemplified in the following description. As exemplified in FIG. 2 and FIG. 3, one direction along the X-axis as viewed from an arbitrary point is denoted as the X1 direction, and the direction opposite to the X1 direction is denoted as the X2 direction. The X-axis direction is a direction including both the X1 direction and the X2 direction. Similarly, mutually opposite directions along the Y-axis from an arbitrary point are denoted as the Y1 direction and the Y2 direction. The Y-axis direction is a direction including both the Y1 direction and the Y2 direction. Moreover, mutually opposite directions along the Z-axis from an arbitrary point are denoted as the Z1 direction and the Z2 direction. The Z-axis direction is a direction including both the Z1 direction and the Z2 direction. Furthermore, the X-Y plane that includes the X-axis and Y-axis corresponds to a horizontal plane. The Z-axis is an axis that runs along the vertical direction.

The ejector 22 has a nozzle 220, a first case section 221, a confluence section 222, a mixing section 223, a first diffuser section 224, and a second diffuser section 225. These elements that make up the ejector 22 are integrally configured.

The nozzle 220 has a flow path 220a through which the driving fluid X1 flows, and is a cylindrical structure extending in the X-axis direction. The nozzle 220 has a tapered surface 220s. The tapered surface 220s gradually reduces the inner diameter of the nozzle 220 in the X1 direction. The nozzle 220 has an injection port 220b for injecting the driving fluid X1. The inlet 220c, located in the X1 direction of the nozzle 220, is connected to the circulation flow path 11.

The first case portion 221 is a housing having an annular space 221a. The annular space 221a is a space defined by the inner peripheral surface of the first case portion 221 and the outer peripheral surface of the nozzle 220. The annular space 221a surrounds the nozzle 220 around the X-axis, with the axis C1 of the ejector 22 as its center. The first case portion 221 has an opening 221b connected to the branch flow path 12. The axis C1 is the central axis of the ejector 22 that is parallel to the X-axis.

The confluence 222 is a portion of the ejector 22 whose inner diameter gradually decreases from the annular space 221a toward the X1 direction. In the confluence 222, the driving fluid X1 ejected from the nozzle 220 and the suction fluid Y1 sucked in with the ejection of the driving fluid X1 join together. The confluence 222 has an outlet 222a. The outlet 222a is the outlet of the confluence 222 through which the driving fluid X1 and the suction fluid Y1 flow. The outlet 222a is located on the boundary B1 between the confluence 222 and the rotor 2230 described below. The confluence 222 surrounds the end of the nozzle 220 located in the X1 direction around the X axis, centered on the axis C1. The boundary B1 is an example of a "first boundary".

The mixing section 223 has a second case section 223a and a variable mechanism 223b. The second case section 223a is provided between the junction section 222 and the first diffuser section 224 and is configured integrally therewith. The second case section 223a may be provided detachably with respect to the junction section 222 and the first diffuser section 224 so that the variable mechanism 223b is incorporated between the junction section 222 and the first diffuser section 224. The second case section 223a is a housing that houses the rotating body 2230 described later.

Figure 4 is a cross-sectional perspective view of the variable mechanism 223b. The variable mechanism 223b has a rotating shaft 2233b, a rotating body 2230, and a flow path 2230b. The rotating shaft 2233b protrudes in the X1 direction from the side surface of the rotating body 2230 located in the X1 direction, and protrudes in the X2 direction from the side surface located in the X2 direction. The rotating shaft 2233b enters the bearing 222b and the bearing 224c (see Figure 2). The bearing 222b is a recess provided on the side surface located in the X1 direction of the confluence section 222. The bearing 224c is a recess provided on the side surface located in the X2 direction of the first diffuser section 224. The rotating shaft 2233b is located on the axis C2. The axis C2 is an axis along the direction (X1 direction) in which the driving fluid X1 is sprayed from the nozzle 220. Therefore, the rotating shaft 2233b is configured to be along that direction.

The rotating body 2230 is a structure that is supported by the rotating shaft 2233b. "Supported" means that the confluence section 222 and the first diffuser section 224 support the rotating body 2230 via the rotating shaft 2233b. The rotating body 2230 rotates around the X-axis with the axis C2 as the center.

The flow path 2230b is a flow path that mixes the driving fluid X1 and the suction fluid Y1 output from the junction 222, and outputs the mixed fluid of the driving fluid X1 and the suction fluid Y1 (hereinafter referred to as the mixed fluid) to the first diffuser section 224. The flow path 2230b includes a first individual flow path 2231 and a second individual flow path 2232.

The first individual flow path 2231 is a through hole provided in the rotor 2230 and extending in the X-axis direction. The first individual flow path 2231 has a first opening 2231a and a second opening 2231b. The first opening 2231a is an inlet of the first individual flow path 2231 to which the driving fluid X1 and the suction fluid Y1 are input from the junction 222. The first opening 2231a is located on the boundary B1. The second opening 2231b is an outlet of the first individual flow path 2231 from which the mixed fluid is output. The second opening 2231b is located on the boundary B2 between the rotor 2230 and the first diffuser section 224 described later. The diameter of the first individual flow path 2231 is constant from the first opening 2231a to the second opening 2231b. The first individual flow path 2231 is an example of a "first through hole", and the boundary B2 is an example of a "second boundary".

The second individual flow path 2232 is a through hole provided in the rotor 2230 and extending in the X-axis direction. The second individual flow path 2232 has a third opening 2232a and a fourth opening 2232b. The third opening 2232a is an inlet of the second individual flow path 2232 to which the driving fluid X1 and the suction fluid Y1 are input from the junction 222. The third opening 2232a is located on the boundary B1. The fourth opening 2232b is an outlet of the second individual flow path 2232 from which the mixed fluid is output. The fourth opening 2232b is located on the boundary B2. The second individual flow path 2232 is composed of a first portion P1, a second portion P2, and a third portion P3. The first portion P1 is a portion of the second individual flow path 2232 whose diameter gradually decreases from the third opening 2232a to the fourth opening 2232b. The second portion P2 is a portion of the second individual flow path 2232 between the first portion P1 and the third portion P3, and has a constant diameter. The diameter of the second portion P2 is smaller than the diameter of the first individual flow path 2231. The third portion P3 is a portion of the second individual flow path 2232 whose diameter gradually increases from the second portion P2 toward the fourth opening 2232b. The second individual flow path 2232 is an example of a "second through hole."

The first diffuser section 224 is a portion of the ejector 22 whose inner diameter increases monotonically from the variable mechanism 223b (inlet 224a) in the X1 direction. The first diffuser section 224 has an inlet 224a and an outlet 224b. The inlet 224a is located on the boundary B2. The outlet 224b is located on the boundary B3 between the first diffuser section 224 and a second diffuser section 225 described below. The first diffuser section 224 according to this embodiment is a portion of the ejector 22 that extends from the boundary B2 to the boundary B3. The first diffuser section 224 is an example of a "diffuser section".

The second diffuser section 225 has an inlet 225a and an outlet 225b. The inlet 225a is located on the boundary B3, as is the outlet 224b. The outlet 225b is connected to the circulation flow path 11. The second diffuser section 225 is a part of the ejector 22 whose inner diameter is constant from the boundary B3 toward the outlet 225b, and is configured in a cylindrical shape.

Figure 5 is a block diagram illustrating a configuration for controlling the variable mechanism 223b. As illustrated in Figure 5, the cooling system 100 has a temperature detection unit 51 and a control unit 52. The temperature detection unit 51 detects the temperature T of the cooling fluid Q2 supplied to the heat dissipation flow path 92. Any type of temperature sensor can be used as the temperature detection unit 51.

The control unit 52 controls the state of the variable mechanism 223b in response to the temperature T detected by the temperature detection unit 51. Specifically, the control unit 52 controls the variable mechanism 223b to either the first communication state or the second communication state in response to the temperature T.

The "first communication state" is a state in which the junction section 222, the first individual flow path 2231, and the first diffuser section 224 are in communication. In the first communication state, the periphery of the outlet 222a and the periphery of the first opening 2231a overlap on the boundary B1, and the periphery of the inlet 224a and the periphery of the second opening 2231b overlap on the boundary B2. "Overlapping" in the first communication state means that the periphery of the outlet 222a and the periphery of the first opening 2231a coincide on the boundary B1, and the periphery of the inlet 224a and the periphery of the second opening 2231b coincide on the boundary B2.

The "second communication state" is a state in which the junction section 222, the second individual flow path 2232, and the first diffuser section 224 are in communication with each other. In the second communication state, the periphery of the outlet 222a and the periphery of the third opening 2232a overlap on the boundary B1, and the periphery of the inlet 224a and the periphery of the fourth opening 2232b overlap on the boundary B2. "Overlapping" in the second communication state means that the periphery of the outlet 222a and the periphery of the third opening 2232a coincide on the boundary B1, and the periphery of the inlet 224a and the periphery of the fourth opening 2232b coincide on the boundary B2. The state of the variable mechanism 223b shown in Figures 2 and 3 is the second communication state.

In this embodiment, as shown in FIG. 4, the diameter of the first individual flow path 2231 is constant, whereas the diameter of the second individual flow path 2232 is not constant (i.e., the second individual flow path 2232 is composed of the first portion P1, the second portion P2, and the third portion P3), so the volume of the first individual flow path 2231 and the volume of the second individual flow path 2232 are different from each other. Therefore, for example, when the variable mechanism 223b is controlled from the first communication state to the second communication state, the volume of the mixed fluid between the junction section 222 and the first diffuser section 224 changes from the volume of the first individual flow path 2231 to the volume of the second individual flow path 2232. Specifically, the volume of the mixed fluid decreases from the volume of the first individual flow path 2231 to the volume of the second individual flow path 2232.

The control unit 52 is realized by a processing circuit such as a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an ASIC (Application Specific Integrated Circuit).

When the temperature T of the cooling fluid Q2 is below a predetermined threshold value RH, the control unit 52 maintains the variable mechanism 223b in the first communication state. When the temperature T changes from a value below the threshold value RH to a value above the threshold value RH, the control unit 52 rotates the rotating body 2230 around the axis C2 to switch from the first communication state to the second communication state. On the other hand, when the temperature T of the cooling fluid Q2 changes from a value above the predetermined threshold value RL to a value below the threshold value RL, the control unit 52 rotates the rotating body 2230 around the axis C2 to switch from the second communication state to the first communication state. The threshold value RL is a value equal to the threshold value RH (RL = RH) or a value below the threshold value RH (RL < RH). By setting the threshold value RL to a value below the threshold value RH, a hysteresis characteristic can be imparted to the state transition between the first communication state and the second communication state. By providing hysteresis characteristics to the state transition, frequent switching between the first and second communication states is prevented when the temperature T rises and falls near the threshold value RH, or when the temperature T rises and falls near the threshold value RL.

When the driving fluid X1 is sprayed from the nozzle 220b into the junction 222, the pressure inside the junction 222 drops and the suction fluid Y1 is sucked into the junction 222 from the opening 221b. The driving fluid X1 and the suction fluid Y1 that have joined at the junction 222 become a mixed fluid and are output from the inlet 224a to the first diffuser section 224. The mixed fluid output to the first diffuser section 224 is pressurized by the first diffuser section 224 and discharged from the outlet 224b. The mixed fluid discharged from the outlet 224b is pressurized by the second diffuser section 225 and discharged from the outlet 225b.

As described above, when the temperature T of the cooling fluid Q2 rises in a high-temperature environment, the temperature difference between the mixed fluid discharged from the ejector 22 and the cooling fluid Q2 becomes smaller, and the amount of heat transferred from the mixed fluid to the cooling fluid Q2 becomes smaller. Therefore, the mixed fluid discharged from the ejector 22 becomes less likely to be condensed by the condenser 24, and the pressure in the circulation flow path 11 connecting the ejector 22 and the condenser 24 increases. When the pressure increases, the mixed fluid becomes less likely to be discharged from the ejector 22. Therefore, the flow rate of the suction fluid Y1 sucked into the ejector 22 (i.e., the flow rate of the refrigerant flowing through the branch flow path 12) decreases, and the ejector efficiency η decreases, resulting in a problem that the ability of the cooling system 100 to continuously cool the cooled medium Q3 (hereinafter referred to as operating ability) decreases.

The ejector efficiency η is a value that is an index of the operating capacity of the cooling system 100. In other words, if the ejector efficiency η is high, the operating capacity of the cooling system 100 is high, and if the ejector efficiency η is low, the operating capacity of the cooling system 100 is low. The ejector efficiency η is expressed, for example, by the following formula (1), where Mm, Ms, Pm, Ps, and Pd are the flow rate of the driving fluid X1 flowing into the ejector 22, the flow rate of the suction fluid Y1 sucked into the ejector 22, the pressure of the driving fluid X1 sprayed from the nozzle 220, the pressure at which the ejector 22 sucks the suction fluid Y1, and the pressure at which the mixed fluid is discharged from the outlet 224b of the first diffuser section 224, respectively. "ln" represents a logarithmic function (natural logarithm) with e as the low.

η=(Ms/Mm)・{ln(Pd/Ps)/ln(Pm/Pd)}...(1)

Increasing the pressure of the driving fluid X1 increases the flow rate of the suction fluid Y1. However, since the pressure of the driving fluid X1 depends on the temperature difference between the hot water Q1 in the steam generator 21 and the refrigerant in the circulation flow path 11, it is practically difficult to sufficiently increase the pressure of the driving fluid X1. Another possible method is to increase the flow rate of the hot water Q1 to suppress the drop in temperature of the hot water Q1 and increase the evaporation temperature of the refrigerant to increase the pressure of the driving fluid X1. However, this increases the power required for the pump 25 that supplies the hot water Q1 to the hot water flow path 91, which increases the size of the entire device or the cost required for cooling.

Considering the above circumstances, the ejector 22 provided in the cooling system 100 of this embodiment has the variable mechanism 223b controlled by the control unit 52 from the first communication state to the second communication state. Here, as described above, the first portion P1 of the second individual flow path 2232 is configured so that the diameter gradually decreases from the third opening 2232a to the fourth opening 2232b. Therefore, the flow rate of the driving fluid X1 ejected from the nozzle 220 increases when it flows from the first portion P1 to the second portion P2, and the vicinity of the boundary B4 (see FIG. 2) between the first portion P1 and the second portion P2 is depressurized by the Venturi effect. Therefore, the flow rate of the suction fluid Y1 sucked from the opening 221b to the confluence portion 222 (i.e., the flow rate of the suction fluid Y1 sucked into the ejector 22) increases compared to the first communication state. In other words, according to the ejector 22 of this embodiment, even if the flow rate of the suction fluid Y1 drawn into the ejector 22 decreases due to an increase in the temperature T of the cooling fluid Q2, the variable mechanism 223b can be switched from the first communication state to the second communication state to temporarily increase the flow rate of the suction fluid Y1 and suppress a decrease in the ejector efficiency η. Therefore, a decrease in the operating capacity of the cooling system 100 is suppressed.

Figure 6 is a graph showing the relationship between the temperature T of the cooling fluid Q2 and the ejector efficiency η of the ejector 22. In Figure 6, the characteristics of this embodiment are shown by a solid line, and the characteristics of the comparative example are shown by a dashed line. The comparative example has the same configuration as the cooling system 100 of this embodiment, except that the ejector 200 is used instead of the ejector 22, as shown in Figure 7. Figure 8 is a cross-sectional view showing an example of the configuration of the ejector 200 of the comparative example. The ejector 200 of the comparative example has the same configuration as the ejector 22, except that the configuration of the mixing section 400 is different from the mixing section 223 of the ejector 22. The mixing section 400 of the ejector 200 is a part of the ejector 200 with a constant inner diameter from the confluence section 222 to the first diffuser section 224, and is configured in a cylindrical shape.

As illustrated in FIG. 6, the ejector efficiency η of the ejector 22 varies according to the temperature T of the cooling fluid Q2. Specifically, the higher the temperature T, the lower the ejector efficiency η. In contrast, when the temperature T of the cooling fluid Q2 reaches a predetermined temperature T1 and exceeds the temperature T1, the ejector efficiency η drops sharply. Therefore, the target operating capacity cannot be achieved in an environment where the temperature exceeds T1.

On the other hand, in this embodiment, when the ejector efficiency η reaches the threshold value RH, the variable mechanism 223b is controlled from the first communication state to the second communication state. As a result, in an environment where the temperature T exceeds the threshold value RH, as shown in FIG. 6, the ejector efficiency η is less likely to decrease compared to the comparative example. Therefore, in this embodiment, the target operating capacity can be maintained even in an environment where the cooling fluid Q2 exceeds the threshold value RH. In other words, according to this embodiment, the decrease in the operating capacity of the cooling system 100 is suppressed more than in the comparative example.

2. Modifications Specific modifications to the above-mentioned embodiments are given below. Two or more modifications selected from the following examples may be combined as long as they are not mutually contradictory.

[Variation 1]
Fig. 9 is a diagram showing a configuration example of an ejector 22A according to a modified example, and Fig. 10 is a cross-sectional perspective view of the ejector 22A. Note that, in each of the embodiments exemplified below, for elements whose functions and configurations are similar to those of the above-described embodiment, the reference numerals used in the above-described embodiment are used, and detailed descriptions of each will be omitted.

As shown in Figures 9 and 10, the ejector 22A has a mixing section 300. The mixing section 300 has a variable mechanism 310. The variable mechanism 310 has a cylindrical section 320, multiple plate-like sections 330, an annular body 340, and a flow path 350. The cylindrical section 320 is a cylindrical structure extending in the X-axis direction. Multiple slits are provided in the cylindrical section 320. Each of the multiple slits extends in the X-axis direction and is provided in the cylindrical section 320 at equal intervals around the X-axis centered on the axis C1.

Each of the multiple plate-like portions 330 is embedded in each of the multiple slits of the cylindrical portion 320 and is configured to be movable radially outward and inward. "Radially outward" refers to the direction from the axis C1 toward the cylindrical portion 320, and "radially inward" refers to the direction from the cylindrical portion 320 toward the axis C1.

Figure 11 is a perspective view showing an example of the configuration of the plate-shaped portion 330. The plate-shaped portion 330 is a flat plate extending in the X-axis direction, and has a main body portion 331 and a protruding portion 332. As shown in Figure 11, the main body portion 331 is a flat plate having a plane surface 331a, a tapered surface 331b, and a tapered surface 331c. The plane surface 331a is parallel to the axis C1 of the ejector 22A and extends in the X-axis direction. The tapered surface 331b is located in the X2 direction from the plane surface 331a, and is inclined radially outward at a predetermined angle from the plane surface 331a. The tapered surface 331c is located in the X1 direction from the plane surface 331a, and is inclined radially outward at a predetermined angle from the plane surface 331a.

The protruding portion 332 is a columnar body that protrudes radially outward from the main body portion 331 and has a hook portion 333. The hook portion 333 protrudes from the protruding portion 332 in the X2 direction and passes through a slit 341 of the annular body 340 described below.

As shown in FIG. 9, the annular body 340 surrounds the outer circumferential surface of the tubular portion 320 around the X-axis and is configured to be rotatable around the X-axis with the axis C1 as the center. The annular body 340 is provided with a plurality of slits 341. As shown in FIG. 9, each of the plurality of slits 341 is provided in the annular body 340 at a predetermined interval. The slits 341 are inserted into the hook portion 333 that protrudes from the protruding portion 332 in the X2 direction.

The flow path 350 is a space defined by each of the multiple planes 331a. The flow path 350 functions in the same manner as the flow path 2230b described above, which mixes the driving fluid X1 and the suction fluid Y1. The volume of the flow path 350 changes as each of the multiple plate-like portions 330 moves radially inward and outward. The flow path 350 is an example of a "flow path."

Ejector 22A has a space (hereinafter referred to as a junction space) defined by each of the multiple tapered surfaces 331b. The junction space functions similarly to junction section 222 of the above-mentioned configuration, and is an example of a "junction section." Ejector 22A also has a space defined by each of the multiple tapered surfaces 331c. This space functions similarly to first diffuser section 224 of the above-mentioned configuration, which pressurizes and discharges the mixed fluid, and is an example of a "diffuser section."

Figures 12 and 13 are explanatory diagrams explaining the operation of the variable mechanism 310. Figure 12 is a view of the ejector 22 in the X2 direction in a state where each of the multiple plate-shaped parts 330 is located at the outermost radial position (hereinafter referred to as the expanded state). Figure 13 is a view of the ejector 22 in the X2 direction in a state where each of the multiple plate-shaped parts 330 is located at the innermost radial position (hereinafter referred to as the throttling state). In the following explanation of the operation, a case where the variable mechanism 310 transitions from the expanded state to the throttling state will be explained as an example of the operation of the variable mechanism 310. The first case part 221 is omitted from illustration in Figures 12 and 13.

In the variable mechanism 310 in the expanded state, when the ejector 22 is viewed in the X2 direction, when the annular body 340 rotates counterclockwise around the axis C2, the slit 341 slides against the hook portion 333 as the annular body 340 rotates, and the edge portion 341a of the slit 341 abuts against the hook portion 333. When the annular body 340 further rotates counterclockwise around the axis C2 with the edge portion 341a abutting against the hook portion 333, as shown in FIG. 13, each of the multiple plate-shaped portions 330 moves radially inward, reducing the volume of the flow path 350 (the area surrounded by the thick solid lines in FIG. 12 and FIG. 13), and the variable mechanism 310 enters a throttled state. Thus, in the ejector 22A according to the first modified example, the variable mechanism 310 transitions from the expanded state to the throttled state, reducing the diameter of the flow path 350. Therefore, the flow rate of the driving fluid X1 that is sprayed from the nozzle 220 and flows into the flow path 350 is higher than in the expanded state, and the pressure in the vicinity of the inlet of the flow path 350 is reduced more than in the expanded state. This causes the flow rate of the suction fluid Y1 that is sucked into the merging space from the opening 221b to be higher than in the expanded state. Therefore, the ejector 22A achieves the same effect as the ejector 22.

[Variation 2]
The ejector 22 of the above-described embodiment is not limited to the configuration exemplified in the drawings. For example, the ejector 22 may further include a positioning mechanism that positions the rotor 2230 when the variable mechanism 223b is in the first communication state or the second communication state.

[Variation 3]
The variable mechanism 223b in the above-described embodiment has two individual flow paths, but is not limited to this, and may have three or more individual flow paths having different volumes.

[Variation 4]
In the above embodiment, the control unit 52 controls the variable mechanism 223b, but the method of controlling the variable mechanism 223b is not limited to the above example. For example, the state of the variable mechanism 223b may be changed in response to a manual operation by an administrator of the cooling system 100. For example, in the above embodiment, the administrator may manually operate the variable mechanism 223b to set it to either the first communication state or the second communication state. Note that, according to the configuration in which the control unit 52 controls the state of the variable mechanism 223b as in the above embodiment, the burden on the administrator of the cooling system 100 can be reduced. Note that the control unit 52 may execute one of the process of changing the variable mechanism 223b from the first communication state to the second communication state and the process of changing the variable mechanism 223b from the second communication state to the first communication state, and the administrator may execute the other.

3. Supplementary Note The effects described in this specification are merely explanatory or exemplary and are not limiting. In other words, the present invention may have other effects that are apparent to a person skilled in the art from the description of this specification, in addition to or in place of the above effects.

The above describes in detail preferred embodiments of the present invention with reference to the attached drawings, but the present invention is not limited to such examples. It is clear that a person with ordinary knowledge in the technical field of the present invention can conceive of various modified or revised examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention.

4. Supplementary Note From the above-described exemplary embodiments, the following configurations can be understood, for example.

The ejector 22 according to one aspect (aspect 1) of the present disclosure includes a confluence section 222 where the driving fluid X1 sprayed from the nozzle 220 and the suction fluid Y1 sucked in with the spray of the driving fluid X1 are joined, a variable mechanism 223b, a mixing section 223 that outputs a mixed fluid obtained by mixing the driving fluid X1 and the suction fluid Y1 output from the confluence section 222, and a first diffuser section 224 that pressurizes and discharges the mixed fluid output from the mixing section 223, and the variable mechanism 223b has a flow path 2230b through which the mixed fluid flows and varies the volume of the flow path 2230b.

In the above embodiment, when the volume of the flow path 2230b changes due to a change in the diameter of the flow path 2230b, if the diameter of the flow path 2230b is changed to, for example, a smaller value, the flow rate of the driving fluid X1 flowing into the flow path 2230b increases compared to before the diameter of the flow path 2230b is changed to a smaller value. Therefore, the flow rate of the suction fluid Y1 sucked in with the injection of the driving fluid X1 increases compared to before the diameter of the flow path 2230b is changed to a smaller value. Therefore, according to the ejector 22, even if the flow rate of the suction fluid Y1 decreases, the flow rate of the suction fluid Y1 can be temporarily increased by changing the volume of the flow path 2230b (specifically, by changing the diameter of the flow path 2230b to a smaller value), thereby suppressing a decrease in the ejector efficiency η. Therefore, a decrease in the operating capacity of the cooling system 100 is suppressed.

According to a specific example (aspect 2) of aspect 1, the flow path 2230b includes a first individual flow path 2231 and a second individual flow path 2232 that have different volumes, and the variable mechanism 223b switches between a first communication state in which the junction 222, the first diffuser section 224, and the first individual flow path 2231 are connected, and a second communication state in which the junction 222, the first diffuser section 224, and the second individual flow path 2232 are connected. In the above aspect, when the diameter of the second individual flow path 2232 is smaller than the diameter of the first individual flow path 2231, the variable mechanism 223b is switched from the first communication state to the second communication state, thereby temporarily increasing the flow rate of the suction fluid Y1 that has decreased, and suppressing the decrease in the ejector efficiency η. Therefore, the operating capacity of the cooling system 100 is suppressed from decreasing.

According to a specific example (aspect 3) of aspect 2, the variable mechanism 223b has a rotating shaft 2233b along the direction in which the driving fluid X1 is ejected from the nozzle 220, and a rotating body 2230 supported by the rotating shaft 2233b, and the rotating body 2230 has a first through hole corresponding to the first individual flow path 2231 and a second through hole corresponding to the second individual flow path 2232. In the above aspect, the first communication state and the second communication state can be switched simply by rotating the rotating body 2230. Therefore, the first communication state and the second communication state can be quickly switched at the timing desired by the manager of the ejector 22 (for example, the time when the temperature T of the cooling fluid Q2 reaches the threshold value RH), improving the convenience of the ejector 22.

According to a specific example (aspect 4) of aspect 3, the junction 222 has an outlet 222a located at the boundary B1 between the rotor 2230 and the junction 222, the first diffuser section 224 has an inlet 224a located at the boundary B2 between the rotor 2230 and the first diffuser section 224, the first through hole has a first opening 2231a and a second opening 2231b, and the second through hole has a third opening 223 In the first communication state, the periphery of the outlet 222a overlaps with the periphery of the first opening 2231a, and the periphery of the inlet 224a overlaps with the periphery of the second opening 2231b, and in the second communication state, the periphery of the outlet 222a overlaps with the periphery of the third opening 2232a, and the periphery of the inlet 224a overlaps with the periphery of the fourth opening 2232b. With this configuration, the driving fluid X1 and the suction fluid Y1 are smoothly output from the confluence section 222 to the first through hole or the second through hole, and the mixed fluid is smoothly output from the first through hole or the second through hole to the first diffuser section 224.

The cooling system 100 according to one aspect (aspect 5) of the present disclosure includes a confluence section 222 where the driving fluid X1 and the suction fluid Y1 sucked in with the spray of the driving fluid X1 join together, a mixing section 223 having a variable mechanism 223b and outputting a mixed fluid in which the driving fluid X1 and the suction fluid Y1 are mixed and output from the confluence section 222, an ejector 22 having a first diffuser section 224 that pressurizes and discharges the mixed fluid output from the mixing section 223, a steam generator 21 that generates the driving fluid X1 by evaporating a refrigerant through heat exchange with a heat source, and a mixed fluid discharged from the ejector 22. The system is equipped with a condenser 24 that converts the mixed fluid into a liquid-phase refrigerant by condensing it through heat exchange between the combined fluid and the cooling fluid Q2, a pump 25 that sends a portion of the liquid-phase refrigerant to the steam generator 21, an expander 31 that reduces the pressure of another portion of the liquid-phase refrigerant, and an evaporator 32 that generates a suction fluid Y1 by evaporating the reduced pressure refrigerant through heat exchange between the refrigerant reduced pressure by the expander 31 and the cooled medium Q3, and supplies the suction fluid Y1 to the ejector 22. The variable mechanism 223b has a flow path 2230b through which the mixed fluid flows, and varies the volume of the flow path 2230b.

According to a specific example of aspect 5 (aspect 6), a temperature detection unit 51 is further provided that detects the temperature T of the cooling fluid Q2, and the control unit 52 controls the state of the variable mechanism 223b in accordance with the temperature T detected by the temperature detection unit 51. In this aspect, the control unit 52 controls the state of the variable mechanism 223b in accordance with the temperature T of the cooling fluid Q2, thereby reducing the burden on the administrator of manually changing the state of the variable mechanism 223b.

220... nozzle, 222... junction, 223, 300, 400... mixing section, 223b, 310... variable mechanism, 224... first diffuser section, 225... second diffuser section, 22a, 220c, 224a, 225a... inlet, 222a... outlet, 2230b... flow path, 2231... first individual flow path, 2232... second individual flow path, rotor... 2230, rotating shaft... 2233b, 2231a... first opening, 2231b... second opening, 2232a... third opening, 2232b... fourth opening, X1... driving fluid, Y1... suction fluid.

Claims (4)

a joining portion where the driving fluid jetted from the nozzle and a suction fluid that is sucked in in association with the jetting of the driving fluid join together;
a mixing section having a variable mechanism and configured to output a mixed fluid obtained by mixing the driving fluid and the suction fluid outputted from the confluence section;
a diffuser unit that pressurizes the mixed fluid output from the mixing unit and discharges the mixed fluid,
The variable mechanism is
a rotation axis along a direction in which the driving fluid is ejected from the nozzle;
a rotor having a first individual flow path and a second individual flow path having different volumes, the rotor being supported by the rotary shaft;
The variable mechanism, by rotation of the rotating body,
a first communication state in which the junction portion, the first individual flow path, and the diffuser portion are in communication with each other;
a second communication state in which the junction portion, the second individual flow path, and the diffuser portion are communicated with each other;
Switches
Ejector. the confluence portion has an outlet located at a first boundary between the rotor and the confluence portion,
the diffuser portion has an inlet located at a second boundary between the rotor and the diffuser portion,
The first individual flow path has a first opening and a second opening,
The second individual flow path has a third opening and a fourth opening,
In the first communication state, a periphery of the outlet and a periphery of the first opening overlap, and a periphery of the inlet and a periphery of the second opening overlap,
The ejector according to claim 1 , wherein in the second communication state, a periphery of the outlet overlaps with a periphery of the third opening, and a periphery of the inlet overlaps with a periphery of the fourth opening. a joining portion where the driving fluid and a suction fluid that is sucked in in association with the ejection of the driving fluid join together;
a mixing section having a variable mechanism and configured to output a mixed fluid obtained by mixing the driving fluid and the suction fluid outputted from the confluence section;
an ejector including a diffuser portion that pressurizes the mixed fluid output from the mixing portion and discharges the mixed fluid;
a vapor generator that generates the driving fluid by evaporating a refrigerant through heat exchange with a heat source;
a condenser that converts the mixed fluid discharged from the ejector into a liquid-phase refrigerant by condensing the mixed fluid through heat exchange between the mixed fluid and a cooling fluid;
a pump for delivering a portion of the liquid phase refrigerant to the steam generator;
an expander for reducing the pressure of another portion of the liquid phase refrigerant;
an evaporator that generates the suction fluid by evaporating the refrigerant decompressed by the expander through heat exchange between the refrigerant and a medium to be cooled, and supplies the suction fluid to the ejector;
The variable mechanism is
a rotation axis along a direction in which the driving fluid is ejected;
a rotor having a first individual flow path and a second individual flow path having different volumes, the rotor being supported by the rotary shaft;
The variable mechanism, by rotation of the rotating body,
a first communication state in which the junction portion, the first individual flow path, and the diffuser portion are in communication with each other;
a second communication state in which the junction portion, the second individual flow path, and the diffuser portion are communicated with each other;
Switches
Cooling system. A temperature detection unit that detects the temperature of the cooling fluid;
The cooling system according to claim 3 , further comprising: a control unit that controls the variable mechanism in response to the temperature detected by the temperature detection unit.

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