Cooling System

Abstract

To suppress deterioration of cooling capacity in a high-temperature environment.SOLUTION: A circulation flow passage 11 in which a refrigerant circulates is formed by annularly connecting a steam generator 21 evaporating the refrigerant, a first ejector 22 mixing and discharging a first drive current X1 supplied from the steam generator 21 and a first suction flow Y1 sucked by the first drive current X1, a condenser 24 condensing the refrigerant by exchanging heat between the refrigerant discharged from the first ejector 22 and cooling fluid Q2 and a pump 25 sending out the refrigerant condensed by the condenser 24 to the steam generator 21. A branch flow passage 12 branched from a portion between the condenser 24 and the pump 25 of the circulation flow passage 11 includes: an expander 31 decompressing the refrigerant condensed by the condenser 24; and an evaporator 32 evaporating the refrigerant decompressed by the expander 31 by exchanging heat with a cooled medium Q3. An auxiliary mechanism 40a sucks the refrigerant discharged from a second ejector 43 and then supplies the refrigerant to the condenser 24.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cooling system. [Background technology]

[0002] A cooling system using an ejector that mixes a suction flow generated by a driving flow with the driving flow and discharges the mixed suction flow has been proposed. For example, Patent Document 1 discloses a configuration in which a conventional cooling system and a cooling system using an ejector are mutually cascaded. The refrigerant discharged from the ejector is condensed by a condenser. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-533046 A Summary of the Invention [Problem to be solved by the invention]

[0004] A condenser that condenses a refrigerant utilizes a cooling fluid such as cooling water or air. For example, in a high-temperature environment such as summer, the temperature of the cooling fluid rises, and the temperature of the refrigerant in the condenser rises, which may result in an increase in the pressure of the discharge flow of the ejector (hereinafter referred to as "back pressure"). When the back pressure increases, the flow rate of the suction flow sucked into the ejector decreases, resulting in a problem of a decrease in cooling capacity. In consideration of the above circumstances, one aspect of the present invention aims to suppress a decrease in cooling capacity in a high-temperature environment. [Means for solving the problem]

[0005] A cooling system according to one embodiment of the present invention includes a steam generator that evaporates a refrigerant by heat exchange with a heat source, a first ejector that introduces the refrigerant evaporated in the steam generator from a first inlet as a first driving flow, mixes it with a first suction flow introduced from a first suction port, and discharges it from a first discharge port, a condenser that condenses the refrigerant discharged from the first ejector by heat exchange with a cooling fluid, and a pump that sends the refrigerant condensed by the condenser to the steam generator, a circulation flow path formed by connecting these in a ring shape, a flow path that connects a branch point between the condenser and the pump in the circulation flow path to the first suction port, the branch flow path including an expander that depressurizes the refrigerant condensed by the condenser and an evaporator that evaporates the refrigerant depressurized by the expander through heat exchange with a cooled medium and supplies it to the first ejector as the first suction flow, and an auxiliary mechanism that draws in the refrigerant discharged from the first ejector and supplies it to the condenser.

[0006] In the above aspect, the first driving flow of the refrigerant introduced from the first inlet of the first ejector sucks in the refrigerant in the branch flow passage, thereby cooling the medium to be cooled. The back pressure of the first ejector is reduced by sucking in the refrigerant discharged from the first ejector by the auxiliary mechanism. Therefore, even in an environment where the cooling fluid used in the condenser becomes hot, the flow rate of the first suction flow by the first ejector is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0007] In a specific aspect of the present invention, the auxiliary mechanism includes an auxiliary flow path that connects a portion of the circulation flow path between the steam generator and the first ejector and a portion of the circulation flow path between the first ejector and the condenser, and a second ejector that is installed in the auxiliary flow path and introduces the refrigerant flowing through the auxiliary flow path as a second driving flow from a second inlet, mixes the refrigerant discharged from the first discharge port and introduced from a second suction port, and discharges the refrigerant from a second discharge port. In the above aspect, the refrigerant discharged from the first ejector is sucked into the second ejector by the second driving flow. The back pressure of the first ejector is reduced by the suction by the second ejector. Therefore, even in an environment where the cooling fluid of the condenser becomes high temperature, the flow rate of the first suction flow by the first ejector is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained. In addition, the second driving flow supplied from the steam generator to the second ejector is a gas-phase refrigerant. Therefore, the capacity required of the pump can be reduced compared to a configuration in which the auxiliary flow path is connected to a portion of the circulation flow path between the pump and the steam generator (a configuration in which liquid phase refrigerant is supplied to the second ejector).

[0008] In a specific aspect of the present invention, the auxiliary mechanism includes an auxiliary flow path that connects a portion of the circulation flow path between the pump and the steam generator and a portion of the circulation flow path between the first ejector and the condenser, and a second ejector that is installed in the auxiliary flow path and introduces the refrigerant flowing through the auxiliary flow path as a second driving flow from a second inlet, discharges the refrigerant from the first discharge port, mixes it with a second suction flow introduced from a second suction port, and discharges it from a second discharge port. In the above aspect, the refrigerant discharged from the first ejector is sucked into the second ejector by the second driving flow. The back pressure of the first ejector is reduced by the suction by the second ejector. Therefore, even in an environment where the cooling fluid of the condenser becomes hot, the flow rate of the first suction flow by the first ejector is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained. In addition, compared to a configuration in which an auxiliary flow path is connected to a portion of the circulation flow path between the steam generator and the first ejector, the flow rate of the refrigerant supplied to the steam generator is reduced, thereby reducing the heat exchange capacity required of the steam generator.

[0009] In a specific aspect of the present invention, the auxiliary mechanism includes an auxiliary flow path that connects a portion of the circulation flow path on the discharge side of the first ejector and a portion of the circulation flow path upstream of the condenser, and a compressor that is installed in the auxiliary flow path and sends the refrigerant discharged from the first ejector to the condenser. In the above aspect, the refrigerant discharged from the first ejector is sucked by the compressor. The back pressure of the first ejector is reduced by the suction by the compressor. Therefore, even in an environment where the cooling fluid of the condenser becomes hot, the flow rate of the first suction flow by the first ejector is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained. In addition, the back pressure of the first ejector can be changed stepwise or continuously by controlling the rotation speed of the compressor.

[0010] A cooling system according to a specific aspect of the present invention includes a control unit that switches between passing and blocking the refrigerant flowing through the auxiliary flow path. In the above aspect, the control unit switches between passing and blocking the refrigerant flowing through the auxiliary mechanism, thereby switching between a state in which the refrigerant discharged from the first ejector is sucked in and supplied to the condenser, and a state in which the suction is stopped.

[0011] A cooling system according to a specific aspect of the present invention includes a temperature detection unit that detects the temperature of the cooling fluid, and the control unit controls the state of the auxiliary mechanism according to the temperature detected by the temperature detection unit. In the above aspect, the control unit controls the state of the auxiliary mechanism according to the temperature of the cooling fluid, thereby reducing the burden on an administrator of manually changing the state of the auxiliary mechanism.

[0012] In a specific aspect of the present invention, a check valve is provided between a first portion of the circulation flow path where the refrigerant discharged from the first ejector is sucked by the auxiliary mechanism and a second portion of the circulation flow path where the refrigerant is supplied from the auxiliary mechanism, the check valve allowing the refrigerant to pass from the first portion toward the second portion and preventing the refrigerant from passing from the second portion toward the first portion. In the above aspect, when the back pressure of the first ejector is reduced by suction by the auxiliary mechanism, a backflow of the refrigerant in the circulation flow path can be prevented. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a configuration diagram of a cooling system according to a first embodiment. [Diagram 2] FIG. [Diagram 3] FIG. 4 is a block diagram illustrating a configuration for controlling an assist mechanism. [Figure 4] 6 is a graph illustrating an example of the relationship between the temperature of the cooling fluid and the back pressure of the first ejector. [Diagram 5] FIG. 11 is a configuration diagram of a cooling system according to a comparative example. [Figure 6] FIG. 11 is a configuration diagram of a cooling system according to a second embodiment. [Figure 7] FIG. 11 is a configuration diagram of a cooling system according to a third embodiment. [Figure 8] FIG. 13 is an explanatory diagram of an operating state in the third embodiment. [Figure 9] 13 is a graph illustrating a relationship between the temperature of the cooling fluid and the back pressure of the first ejector in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A: First embodiment FIG. 1 is a configuration diagram of a cooling system 100 according to a first embodiment of the present invention. The cooling system 100 is a system for cooling 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 illustrated in FIG. 1, the cooling system 100 of the first embodiment includes a circulation flow path 11 and a branch flow path 12. A refrigerant flows through the circulation flow path 11 and the branch flow path 12.

[0015] A steam generator 21, a first ejector 22, a check valve 23, a condenser 24, and a pump 25 are installed in the above order in the circulation flow path 11. The refrigerant in the circulation flow path 11 moves in the order of the steam generator 21 → the first ejector 22 → the check valve 23 → the condenser 24 → the pump 25 → the steam generator 21. That is, the circulation flow path 11 is formed by connecting the steam generator 21, the first ejector 22, the condenser 24, and the pump 25 in a ring shape.

[0016] The steam generator 21 is a heat exchanger (recovery device) that evaporates a refrigerant by exchanging heat 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 factory wastewater or used cooling water.

[0017] The first ejector 22 includes a first inlet 22a, a first suction port 22b, and a first outlet 22c. The gas-phase refrigerant discharged from the steam generator 21 is supplied to the first inlet 22a as a first driving flow X1. The first ejector 22 draws the refrigerant in the branch passage 12 as a first suction flow Y1 from the first suction port 22b due to a static pressure drop caused by the first driving flow X1. The first driving flow X1 supplied to the first inlet 22a and the first suction flow Y1 supplied to the first suction port 22b are mixed, and the mixed gas-phase refrigerant is pressurized by a diffuser and then discharged from the first outlet 22c. As described above, the first ejector 22 of the first embodiment introduces the refrigerant evaporated in the steam generator 21 as the first driving flow X1 from the first inlet 22a, mixes it with the first suction flow Y1 introduced from the first suction port 22b, and discharges it from the first discharge port 22c.

[0018] The check valve 23 is installed between the first ejector 22 and the condenser 24. Specifically, the check valve 23 is installed between a portion N1 located downstream of the first ejector 22 in the circulation flow path 11 and a portion N2 located between the portion N1 and the condenser 24. The check valve 23 is a valve mechanism that passes refrigerant in the forward direction from the portion N1 to the portion N2 and blocks refrigerant in the reverse direction from the portion N2 to the portion N1. The portion N1 is an example of the "first portion" and the portion N2 is an example of the "second portion".

[0019] The condenser 24 condenses the gas phase refrigerant discharged from the first ejector 22. Specifically, the condenser 24 condenses the refrigerant by heat exchange between the cooling fluid Q2 supplied to the heat dissipation flow path 92 and the refrigerant in the circulation flow path 11. 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.

[0020] The pump 25 is a liquid-phase pump that sends the liquid-phase refrigerant condensed by the condenser 24 to the steam generator 21. The refrigerant in the circulation flow path 11 is pressurized by the pump 25 to a driving pressure of the first ejector 22.

[0021] The branch flow passage 12 is a flow passage branched from the circulation flow passage 11. That is, a part of the refrigerant flowing through the circulation flow passage 11 is supplied to the branch flow passage 12. Specifically, the branch flow passage 12 connects a portion N3 between the condenser 24 and the pump 25 of the circulation flow passage 11 and the first suction port 22b of the first ejector 22. That is, the branch flow passage 12 is a flow passage that supplies the refrigerant that becomes the first suction flow Y1 to the first ejector 22. The portion N3 corresponds to a branch point between the circulation flow passage 11 and the branch flow passage 12. The branch flow passage 12 is a flow passage that includes an expander 31 and an evaporator 32. The evaporator 32 is located between the expander 31 and the first suction port 22b of the first ejector 22.

[0022] A portion of the refrigerant condensed by the condenser 24 is supplied to the expander 31. The expander 31 expands the refrigerant in the branch passage 12 by reducing its pressure. Any type of pressure reducing mechanism, such as an electronic expansion valve, a manual expansion valve, a constant pressure expansion valve, an orifice, or a capillary, is used as the expander 31.

[0023] The evaporator 32 is a heat exchanger that evaporates a refrigerant by heat exchange between the cooled medium Q3 supplied to the cooled flow path 93 and a liquid-phase medium decompressed by the expander 31. The evaporator 32 supplies the evaporated gas-phase refrigerant as a first suction flow Y1 to the first suction port 22b of the first ejector 22. The cooled medium Q3 is cooled by utilizing the latent heat of the refrigerant whose pressure has been reduced by suction from the first ejector 22.

[0024] As described above, when the temperature T of the cooling fluid Q2 rises in a high-temperature environment, the condensation temperature of the refrigerant rises, which may increase the pressure (back pressure B) of the discharge flow of the first ejector 22. When the back pressure B of the first ejector 22 rises, the flow rate of the first suction flow Y1 sucked into the first ejector 22 (i.e., the flow rate of the refrigerant flowing through the branch flow path 12) decreases, resulting in a problem that the ability of the cooling system 100 to cool the cooled medium Q3 (hereinafter referred to as "cooling ability") decreases.

[0025] Increasing the pressure of the first driving flow X1 increases the flow rate of the first suction flow Y1. However, since the pressure of the first driving flow 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 first driving flow X1. Another possible method is to increase the flow rate of the hot water Q1 to suppress a decrease in the temperature of the hot water Q1 and increase the evaporation temperature of the refrigerant to increase the pressure of the first driving flow X1. However, this increases the power required for the pump 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.

[0026] In consideration of the above circumstances, the cooling system 100 of the first embodiment includes an auxiliary mechanism 40a that draws in the refrigerant discharged from the first ejector 22 and supplies the refrigerant to the condenser 24. The back pressure B of the first ejector 22 decreases due to the suction of the refrigerant by the auxiliary mechanism 40a. Therefore, even in an environment where the cooling fluid Q2 becomes hot, the flow rate of the first suction flow Y1 by the first ejector 22 is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0027] 1, the auxiliary mechanism 40a of the first embodiment includes an auxiliary flow path 41a, a switching mechanism 42, a second ejector 43, and a suction flow path 44. The auxiliary flow path 41a is a flow path that connects a portion N4 of the circulation flow path 11 between the steam generator 21 and the first ejector 22 and a portion N2 of the circulation flow path 11 between the first ejector 22 and the condenser 24. The switching mechanism 42 and the second ejector 43 are installed in the auxiliary flow path 41a. Specifically, the switching mechanism 42 is located between the portion N4 of the circulation flow path 11 and the second ejector 43.

[0028] The switching mechanism 42 is an on-off valve that switches between passing and blocking the refrigerant in the auxiliary flow path 41a. That is, the switching mechanism 42 is set to either an open state in which the refrigerant supplied from the steam generator 21 to the auxiliary flow path 41a passes through, or a blocked state in which the refrigerant in the auxiliary flow path 41a is blocked. When the switching mechanism 42 is in the open state, a part of the refrigerant discharged from the steam generator 21 is supplied to the first ejector 22, and another part of the refrigerant passes through the switching mechanism 42 and is supplied to the second ejector 43. On the other hand, when the switching mechanism 42 is in the blocked state, the refrigerant discharged from the steam generator 21 is supplied only to the first ejector 22. That is, the supply of the refrigerant to the second ejector 43 is stopped.

[0029] The second ejector 43 includes a second inlet 43a, a second suction port 43b, and a second outlet 43c. The suction flow path 44 is a flow path that connects the portion N1 of the circulation flow path 11 and the second suction port 43b of the second ejector 43. That is, the first outlet 22c of the first ejector 22 and the second suction port 43b of the second ejector 43 are mutually communicated via the suction flow path 44. In addition, the second outlet 43c of the second ejector 43 is communicated with the portion N2 of the circulation flow path 11.

[0030] The refrigerant that has passed through the switching mechanism 42 in the open state is supplied to the second inlet 43a of the second ejector 43 as the second driving flow X2. Due to a static pressure drop generated in the second ejector 43 by the second driving flow X2, the refrigerant discharged from the first ejector 22 is sucked into the second suction port 43b through the suction flow path 44. That is, the second ejector 43 introduces the refrigerant flowing through the auxiliary flow path 41a from the second inlet 43a as the second driving flow X2, mixes it with the second suction flow Y2 discharged from the first discharge port 22c and introduced from the second suction port 43b, and discharges it from the second discharge port 43c. The back pressure B of the first ejector 22 is reduced by the suction by the second ejector 43.

[0031] In the above configuration, when the switching mechanism 42 is in the shutoff state, the flow of the refrigerant in the auxiliary flow path 41a is shut off by the switching mechanism 42, so that the second driving flow X2 and the second suction flow Y2 are not generated in the second ejector 43. That is, by controlling the switching mechanism 42 to the shutoff state, the auxiliary mechanism 40a is set to a state in which the suction of the refrigerant discharged from the first ejector 22 is stopped (hereinafter referred to as the "stop state"). In the stop state, the refrigerant in the branch flow path 12 is sucked into the first ejector 22 by the circulation of the refrigerant in the circulation flow path 11, so that the cooled medium Q3 is cooled. The refrigerant discharged from the first ejector 22 passes through the check valve 23 and is supplied to the condenser 24.

[0032] On the other hand, when the switching mechanism 42 is in the open state, as illustrated in Fig. 2, the refrigerant discharged from the steam generator 21 is supplied to both the first ejector 22 and the second ejector 43. The characteristics of each of the first ejector 22 and the second ejector 43 are selected so that the flow rate of the portion of the refrigerant discharged from the steam generator 21 that is supplied to the second ejector 43 exceeds the flow rate of the portion that is supplied to the first ejector 22. That is, the characteristics of the first ejector 22 and the characteristics of the second ejector 43 may be different.

[0033] A first driving flow X1 is generated by supplying a refrigerant to the first inlet 22a of the first ejector 22. The first driving flow X1 draws the refrigerant in the branch passage 12 into the first suction port 22b, thereby cooling the cooled medium Q3. A second driving flow X2 is generated by supplying a refrigerant to the second inlet 43a of the second ejector 43 via the switching mechanism 42. The refrigerant discharged from the first ejector 22 is drawn from the suction passage 44 into the second suction port 43b by the second driving flow X2. That is, the second ejector 43 mixes the second driving flow X2 and the second suction flow Y2 and discharges them. The refrigerant mixed by the second ejector 43 is supplied to the condenser 24 via the portion N2. As can be understood from the above explanation, when the switching mechanism 42 is controlled to the open state, the auxiliary mechanism 40a is set to a state (hereinafter referred to as the “operating state”) in which it draws in the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24.

[0034] As illustrated above, the auxiliary mechanism 40a of the first embodiment switches between an operating state in which the auxiliary mechanism 40a sucks in the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24, and a stopped state in which the suction is stopped. In the operating state, the back pressure B of the first ejector 22 is reduced by the suction by the second ejector 43.

[0035] In addition, in the operating state, the back pressure B of the first ejector 22 decreases, and therefore the pressure in the portion N1 of the circulation flow path 11 may become lower than the pressure in the portion N2. However, the backflow of the refrigerant from the portion N2 to the portion N1 is prevented by the check valve 23. In the operating state, a part of the refrigerant discharged from the first ejector 22 may be supplied to the condenser 24 via the check valve 23.

[0036] Fig. 3 is a block diagram illustrating a configuration for controlling the auxiliary mechanism 40a (switching mechanism 42). As illustrated in Fig. 3, the cooling system 100 includes 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 is used as the temperature detection unit 51.

[0037] The control unit 52 controls the state of the auxiliary mechanism 40a in response to the temperature T detected by the temperature detection unit 51. Specifically, the control unit 52 controls the switching mechanism 42 to either an open state or a cut-off state in response to the temperature T. 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).

[0038] When the temperature T of the cooling fluid Q2 is below a predetermined threshold value RH, the control unit 52 maintains the switching mechanism 42 in the cut-off 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 changes the switching mechanism 42 from the cut-off state to the open state. That is, the control unit 52 transitions the auxiliary mechanism 40a from the stopped state to the operating state of FIG. 2. On the other hand, when the temperature T of the cooling fluid Q2 changes from a value above a predetermined threshold value RL to a value below the threshold value RL, the control unit 52 changes the switching mechanism 42 from the open state to the cut-off state. That is, the control unit 52 transitions the auxiliary mechanism 40a from the operating state to the stopped state. The threshold value RL is set to a value equal to the threshold value RH (RL=RH) or a value below the threshold value RH (RL <RH)である。

[0039] As described above, when the auxiliary mechanism 40a is in operation, the refrigerant discharged from the first ejector 22 is sucked by the auxiliary mechanism 40a, thereby decreasing the back pressure B of the first ejector 22. Therefore, even in an environment where the cooling fluid Q2 used in the condenser 24 has a high temperature, the flow rate of the first suction flow Y1 by the first ejector 22 is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0040] FIG. 4 is a graph showing the relationship between the temperature T of the cooling fluid Q2 and the back pressure B of the first ejector 22. In FIG. 4, the characteristics of the first embodiment are shown by a solid line, and the characteristics of the comparative example are shown by a dashed line. As illustrated in FIG. 5, the comparative example is a configuration in which the auxiliary mechanism 40a and the check valve 23 are omitted from the first embodiment. The operation limit Bmax in FIG. 4 is the maximum value of the back pressure B for achieving the target cooling capacity. That is, when the back pressure B exceeds the operation limit Bmax, the flow rate of the first suction flow Y1 in the first ejector 22 is not sufficiently ensured, and as a result, the target cooling capacity cannot be realized.

[0041] 4, the back pressure B of the first ejector 22 varies according to the temperature T of the cooling fluid Q2. Specifically, the higher the temperature T, the higher the back pressure B. In contrast, when the temperature T of the cooling fluid Q2 rises to a predetermined temperature T1 on the high temperature side, the back pressure B reaches the operation limit Bmax. Therefore, in an environment where the temperature exceeds T1, the target cooling capacity cannot be achieved.

[0042] On the other hand, in the first embodiment, the auxiliary mechanism 40a transitions to the operating state at the stage where the temperature T of the cooling fluid Q2 reaches the threshold value RH from the low temperature side. That is, in an environment where the temperature T exceeds the threshold value RH, as illustrated in FIG. 4, the back pressure B of the first ejector 22 is reduced compared to the comparative example. For example, in the comparative example, the back pressure B reaches the operating limit Bmax at the temperature T1, whereas in the first embodiment, the back pressure B at the temperature T1 is below the operating limit Bmax. Therefore, in the first embodiment, the target cooling capacity can be achieved even in an environment where the cooling fluid Q2 exceeds the temperature T1. That is, according to the first embodiment, the temperature range in which the cooling system 100 can operate can be expanded.

[0043] FIG. 6 of Patent Document 1 discloses a cooling system including a first ejector and a second ejector. Specifically, the discharge flow of the first ejector is compressed by a compressor, and the compressed driving flow is supplied to the second ejector, so that the discharge flow of the first ejector is sucked in. However, the technology of Patent Document 1 requires a compressor that generates the driving flow of the second ejector by compressing the discharge flow of the first ejector. In contrast to the technology of Patent Document 1, the first embodiment does not require a compressor that compresses the discharge flow of the first ejector, so there is an advantage that the scale of the cooling system can be easily reduced compared to Patent Document 1.

[0044] B: Second embodiment A second embodiment of the present invention will be described. Note that, in the configurations exemplified below, for elements whose functions are similar to those of the first embodiment, the reference numerals used in the description of the first embodiment will be used and detailed descriptions of each will be omitted as appropriate.

[0045] Fig. 6 is a configuration diagram of a cooling system 100 according to a second embodiment. In the second embodiment, the auxiliary mechanism 40a in the first embodiment is replaced with an auxiliary mechanism 40b in Fig. 6. The auxiliary mechanism 40b sucks the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24, similar to the auxiliary mechanism 40a.

[0046] As illustrated in FIG. 6, the auxiliary mechanism 40b of the second embodiment has a configuration in which the auxiliary flow path 41a in the auxiliary mechanism 40a of the first embodiment is replaced with an auxiliary flow path 41b. The configuration other than the auxiliary flow path 41b is the same as that of the first embodiment. In the first embodiment, the upstream end of the auxiliary flow path 41a is connected to a portion N4 of the circulation flow path 11 downstream of the steam generator 21. In the second embodiment, as illustrated in FIG. 6, the upstream end of the auxiliary flow path 41b is connected to a portion N5 of the circulation flow path 11 between the pump 25 and the steam generator 21. That is, the auxiliary flow path 41b of the second embodiment is a flow path that connects the portion N5 of the circulation flow path 11 between the pump 25 and the steam generator 21 and the portion N2 of the circulation flow path 11 between the first ejector 22 and the condenser 24. A switching mechanism 42 and a second ejector 43 are installed in the auxiliary flow path 41b.

[0047] The functions of the switching mechanism 42, the second ejector 43, and the suction flow path 44 are the same as those in the first embodiment. The switching mechanism 42 switches between passing and blocking the refrigerant in the auxiliary flow path 41b. Specifically, as in the first embodiment, the control unit 52 controls the state of the switching mechanism 42 according to the temperature T detected by the temperature detection unit 51. When the switching mechanism 42 is in an open state, a part of the liquid-phase refrigerant discharged from the pump 25 is supplied to the steam generator 21, and another part of the refrigerant passes through the switching mechanism 42 and is supplied to the second ejector 43. On the other hand, when the switching mechanism 42 is in a blocked state, the refrigerant discharged from the pump 25 is supplied only to the steam generator 21.

[0048] The second ejector 43 mixes and discharges the second driving flow X2 that has passed through the switching mechanism 42 in the open state and the second suction flow Y2 that is sucked from the first discharge port 22c of the first ejector 22 by the second driving flow X2. The second ejector 43 of the first embodiment is supplied with the first driving flow X1 in gas phase and the first suction flow Y1 in gas phase. On the other hand, the second embodiment is similar to the first embodiment in that the gas phase refrigerant is supplied to the second suction port 43b of the second ejector 43, but is different from the first embodiment in that the liquid phase refrigerant delivered from the pump 25 is supplied to the second inlet 43a. That is, the second ejector 43 of the second embodiment is a two-phase flow ejector that mixes the second driving flow X2 in liquid phase and the second suction flow Y2 in gas phase.

[0049] When the switching mechanism 42 is in the shutoff state, the flow of the refrigerant in the auxiliary flow path 41a is shut off by the switching mechanism 42, so that the second driving flow X2 and the second suction flow Y2 are not generated in the second ejector 43. That is, the auxiliary mechanism 40b is set to a stopped state. On the other hand, when the switching mechanism 42 is in an open state, the liquid-phase refrigerant delivered from the pump 25 is supplied to the steam generator 21 and the second ejector 43. Therefore, the auxiliary mechanism 40b is set to an operating state in which the auxiliary mechanism 40b sucks in the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24.

[0050] As described above, in the second embodiment, similarly to the first embodiment, the first driving flow X1 of the refrigerant supplied from the steam generator 21 to the first ejector 22 draws in the refrigerant in the branch passage 12, thereby cooling the cooled medium Q3. In addition, in the operating state of the auxiliary mechanism 40b, as described with reference to Fig. 4, the back pressure B of the first ejector 22 is reduced by drawing in the refrigerant discharged from the first ejector 22 by the auxiliary mechanism 40b. Therefore, even in an environment where the cooling fluid Q2 used in the condenser 24 has a high temperature, the flow rate of the first suction flow Y1 by the first ejector 22 is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0051] In the second embodiment, in the operating state of the auxiliary mechanism 40b, a part of the refrigerant discharged from the pump 25 is supplied to the second ejector 43. That is, compared to the first embodiment in which the auxiliary flow path 41a is connected to the portion N4 between the steam generator 21 and the first ejector 22 of the circulation flow path 11, the flow rate of the refrigerant supplied to the steam generator 21 in the operating state is reduced. Therefore, there is an advantage that the heat exchange capacity required of the steam generator 21 can be reduced. On the other hand, in the first embodiment, in the operating state of the auxiliary mechanism 40a, the second driving flow X2 supplied from the steam generator 21 to the second ejector 43 is a gas-phase refrigerant. Therefore, compared to the second embodiment in which the auxiliary flow path 41b is connected to the portion N5 between the pump 25 and the steam generator 21 of the circulation flow path 11 (the configuration in which the liquid-phase refrigerant is supplied to the second ejector 43), there is an advantage that the capacity required of the pump 25 can be reduced.

[0052] C: Third embodiment Fig. 7 is a configuration diagram of a cooling system 100 according to a third embodiment. In the third embodiment, the auxiliary mechanism 40a in the first embodiment is replaced with an auxiliary mechanism 40c in Fig. 7. The auxiliary mechanism 40c, like the auxiliary mechanism 40a or the auxiliary mechanism 40b described above, draws in the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24. As illustrated in Fig. 7, the auxiliary mechanism 40c of the second embodiment includes an auxiliary flow path 41c and a compressor 46.

[0053] The auxiliary flow path 41c is a flow path that connects a portion N1 of the circulation flow path 11 on the discharge side of the first ejector 22 and a portion N2 of the circulation flow path 11 upstream of the condenser 24. The configuration in which the check valve 23 is provided between the portion N1 and the portion N2 in the circulation flow path 11 is similar to that in the first embodiment.

[0054] The compressor 46 is installed in the auxiliary flow path 41c. The compressor 46 is a pump that sends the gas phase refrigerant discharged from the first ejector 22 to the condenser 24. For example, any type of compressor 46 that pressurizes and sends the refrigerant in the auxiliary flow path 41c by the rotational motion of a rotor or the reciprocating motion of a piston may be used. The rotation speed of the compressor 46 in the third embodiment changes in response to an instruction from the control unit 52.

[0055] When the compressor 46 is stopped, the flow of refrigerant in the auxiliary flow path 41c is blocked by the compressor 46. In the above state, the auxiliary mechanism 40c is set to a stopped state in which the suction of the refrigerant discharged from the first ejector 22 is stopped. In the stopped state, the refrigerant in the branch flow path 12 is sucked into the first ejector 22 by the circulation of the refrigerant in the circulation flow path 11, thereby cooling the cooled medium Q3. The refrigerant discharged from the first ejector 22 passes through the check valve 23 and is supplied to the condenser 24.

[0056] 8, the refrigerant discharged from the first ejector 22 is sucked by the compressor 46 and sent to the condenser 24. That is, the auxiliary mechanism 40c is set to an operating state in which the auxiliary mechanism 40c sucks the refrigerant discharged from the first ejector 22 and supplies it to the condenser 24.

[0057] As illustrated above, the auxiliary mechanism 40c of the third embodiment is switched between an operating state and a stopped state. In the operating state, the back pressure B of the first ejector 22 is reduced by suction by the compressor 46. The degree to which the auxiliary mechanism 40c reduces the back pressure B of the first ejector 22 in the operating state varies depending on the rotation speed of the compressor 46. Specifically, the higher the rotation speed of the compressor 46, the greater the degree to which the auxiliary mechanism 40c reduces the back pressure B of the first ejector 22. In addition, in the operating state, the pressure in the portion N1 of the circulation flow passage 11 may fall below the pressure in the portion N2, but as in the first embodiment, the check valve 23 prevents the refrigerant from flowing back from the portion N2 to the portion N1. In addition, in the operating state, a part of the refrigerant discharged from the first ejector 22 may be supplied to the condenser 24 via the check valve 23.

[0058] The control unit 52 of the third embodiment controls the state of the auxiliary mechanism 40c according to the temperature T detected by the temperature detection unit 51, as in the first embodiment. Specifically, the control unit 52 operates the compressor 46 when the temperature T of the cooling fluid Q2 changes from a value below a predetermined threshold value RH to a value above the threshold value RH. That is, the control unit 52 transitions the auxiliary mechanism 40c from a stopped state to an operating state. In addition, in the operating state, the control unit 52 controls the rotation speed of the compressor 46 according to the temperature T. Specifically, the more the temperature T rises in a range above the threshold value RH, the more the rotation speed of the compressor 46 is increased. On the other hand, the control unit 52 stops the operation of the compressor 46 when the temperature T changes from a value above a predetermined threshold value RL (RL≦RH) to a value below the threshold value RL. That is, the control unit 52 transitions the auxiliary mechanism 40c from an operating state to a stopped state.

[0059] Fig. 9 is a graph showing the relationship between the temperature T of the cooling fluid Q2 and the back pressure B of the first ejector 22 in the third embodiment. In Fig. 9, similar to Fig. 4, the characteristics of the third embodiment are shown by a solid line, and the characteristics of the comparative example shown in Fig. 5 are shown by a dashed line.

[0060] In the third embodiment, the auxiliary mechanism 40c transitions to an operating state when the temperature T of the cooling fluid Q2 reaches the threshold value RH. That is, in an environment where the temperature T exceeds the threshold value RH, the back pressure B of the first ejector 22 is reduced compared to the comparative example. Specifically, while the back pressure B reaches the operating limit Bmax at the temperature T1 in the comparative example, in the third embodiment, the back pressure B at the temperature T1 falls below the operating limit Bmax. That is, in the first embodiment, the target cooling capacity can be achieved even in an environment where the cooling fluid Q2 exceeds the temperature T1. That is, according to the third embodiment, the temperature range in which the cooling system 100 can operate can be expanded, similarly to the first embodiment.

[0061] In the third embodiment, as can be seen from Fig. 9, the rotation speed of the compressor 46 is controlled in response to the temperature T so that the back pressure B of the first ejector 22 is maintained constant with respect to changes in the temperature T within a range exceeding the threshold value RH. Specifically, the higher the temperature T, the greater the degree to which the auxiliary mechanism 40c reduces the back pressure B. The temperature T2 in Fig. 9 is the temperature T at which the rotation speed of the compressor 46 reaches a maximum value when the rotation speed is changed in response to the temperature T. That is, in an environment in which the temperature T of the cooling fluid Q2 exceeds the temperature T2, the rotation speed of the compressor 46 is maintained at a maximum value, and therefore the back pressure B of the first ejector 22 changes in response to the temperature T.

[0062] As described above, in the third embodiment, similarly to the first embodiment, the first driving flow X1 of the refrigerant supplied from the steam generator 21 to the first ejector 22 draws in the refrigerant in the branch passage 12, thereby cooling the cooled medium Q3. In addition, in the operating state of the auxiliary mechanism 40c, the back pressure B of the first ejector 22 is reduced by drawing in the refrigerant discharged from the first ejector 22 by the auxiliary mechanism 40c. Therefore, even in an environment where the cooling fluid Q2 used in the condenser 24 has a high temperature, the flow rate of the first suction flow Y1 by the first ejector 22 is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0063] In the third embodiment, the rotation speed of the compressor 46 is controlled in response to the temperature T, so that it is possible to change in a stepwise or continuous manner the degree to which the auxiliary mechanism 40c reduces the back pressure B of the first ejector 22. Therefore, as illustrated in FIG. 9, it is possible to maintain the back pressure B constant with respect to the change in temperature T.

[0064] D: Variation Specific modified embodiments added to each of the above-mentioned embodiments are exemplified below. Two or more embodiments selected from the following examples may be appropriately combined as long as they are not mutually contradictory.

[0065] (1) In the first and second embodiments, the switching mechanism 42 is controlled to be in a binary manner between an open state and a shutoff state, but the switching mechanism 42 may be controlled to be in one of multiple stages between the open state and the shutoff state. For example, an adjustment valve that adjusts the flow rate of the refrigerant in the auxiliary flow path 41a (or the auxiliary flow path 41b) stepwise or continuously may be used as the switching mechanism 42. According to the above configuration, the difference between the back pressure B of the first ejector 22 in the operating state and the back pressure B of the first ejector 22 in the stopped state can be reduced. That is, in the first and second embodiments, the back pressure B of the first ejector 22 can be controlled in the same manner as in the third embodiment (FIG. 9).

[0066] (2) In the third embodiment, the rotation speed of the compressor 46 is controlled according to the temperature T, but the operation / stop of the compressor 46 may be controlled in a binary manner. For example, the control unit 52 operates the compressor 46 when the temperature T of the cooling fluid Q2 exceeds the threshold value RH, and stops the compressor 46 when the temperature T falls below the threshold value RL. The rotation speed of the compressor 46 during operation is constant. The above configuration has the advantage of simplifying the control of the auxiliary mechanism 40c.

[0067] (3) In each of the above-described embodiments, the auxiliary mechanism 40 (40a, 40b, 40c) is controlled according to the temperature T of the cooling fluid Q2. However, the index applied to the control of the auxiliary mechanism 40 is not limited to the temperature T. For example, the pressure of the refrigerant in a portion (e.g., portion N2) upstream of the condenser 24 in the circulation flow path 11 is linked to the temperature T of the cooling fluid Q2. Therefore, the control unit 52 may control the auxiliary mechanism 40 according to the pressure of the refrigerant in the portion N2. For example, the control unit 52 controls the auxiliary mechanism 40 to an operating state when the pressure of the portion N2 exceeds the threshold RH, and controls the auxiliary mechanism 40 to a stopped state when the pressure of the portion N2 is below the threshold RL. In addition, the flow rate of the first suction flow Y1 in the first ejector 22 is linked to the temperature T of the cooling fluid Q2. Therefore, the control unit 52 may control the auxiliary mechanism 40 according to the flow rate of the first suction flow Y1. For example, the control unit 52 controls the auxiliary mechanism 40 to an operating state when the flow rate of the first suction flow Y1 exceeds the threshold RH, and controls the auxiliary mechanism 40 to a stopped state when the flow rate falls below the threshold RL. As can be understood from the above examples, any index linked to the temperature T of the cooling fluid Q2 (for example, the temperature T itself, the pressure of the portion N2, or the flow rate of the first suction flow Y1) is applied to the control of the auxiliary mechanism 40.

[0068] (4) In each of the above-mentioned embodiments, the control unit 52 controls the auxiliary mechanism 40 (40a, 40b, 40c), but the method of controlling the state of the auxiliary mechanism 40 is not limited to the above examples. For example, a configuration in which the state of the auxiliary mechanism 40 is changed in response to a manual operation by an administrator of the cooling system 100 is also assumed. For example, in the first and second embodiments, the administrator may manually operate the switching mechanism 42 to set the auxiliary mechanism 40 to either an open state or a blocked state. In addition, in the third embodiment, the administrator may manually operate the compressor 46 to switch between operation / stop (or the rotation speed during operation) of the compressor 46. Note that, according to the configuration in which the control unit 52 controls the state of the auxiliary mechanism 40 as in each of the above-mentioned embodiments, 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 auxiliary mechanism 40 from a stopped state to an operating state and the process of changing the auxiliary mechanism 40 from an operating state to a stopped state, and the administrator may execute the other process manually. [Explanation of symbols]

[0069] 100...cooling system, 11...circulation flow path, 12...branch flow path, 21...steam generator, 22...first ejector, 22a...first inlet, 22b...first suction port, 22c...first discharge port, 23...check valve, 24...condenser, 25...pump, 31...expander, 32...evaporator, 40a, 40b, 40c...auxiliary mechanism, 41a, 41b, 41c...auxiliary flow path, 42...switching mechanism, 43...second ejector, 43a...second inlet, 43b...second suction port, 43c...second discharge port, 44...suction flow path, 46...compressor, 51...temperature detection unit, 52...control unit, 91...hot water flow path, 92...heat dissipation flow path, 93...cooled flow path.

Claims

1. a circulation flow path including a steam generator that evaporates a refrigerant by heat exchange with a heat source, a first ejector that introduces the refrigerant evaporated in the steam generator from a first inlet as a first driving flow, mixes the refrigerant with a first suction flow introduced from a first suction port, and discharges the refrigerant from a first discharge port, a condenser that condenses the refrigerant discharged from the first ejector by heat exchange with a cooling fluid, and a pump that sends the refrigerant condensed by the condenser to the steam generator, connected in a ring shape; a branch flow path connecting a branch point between the condenser and the pump in the circulation flow path and the first suction port, the branch flow path including an expander that reduces the pressure of the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant reduced in pressure by the expander through heat exchange with a cooled medium and supplies the refrigerant to the first ejector as the first suction flow; an auxiliary mechanism that draws in the refrigerant discharged from the first ejector and supplies the refrigerant to the condenser; Equipped with The auxiliary mechanism includes: an auxiliary flow path connecting a third portion of the circulation flow path between the steam generator and the first ejector and a portion of the circulation flow path between the first ejector and the condenser; a second ejector that is installed in the auxiliary flow path, introduces the refrigerant flowing through the auxiliary flow path from a second inlet as a second driving flow, mixes the refrigerant with a second suction flow discharged from the first discharge port and introduced from a second suction port, and discharges the mixed refrigerant from the second discharge port, The circulation flow path includes a portion that connects the first discharge port and the condenser without passing through the second ejector. Cooling system.

2. a circulation flow path including a steam generator that evaporates a refrigerant by heat exchange with a heat source, a first ejector that introduces the refrigerant evaporated in the steam generator from a first inlet as a first driving flow, mixes the refrigerant with a first suction flow introduced from a first suction port, and discharges the refrigerant from a first discharge port, a condenser that condenses the refrigerant discharged from the first ejector by heat exchange with a cooling fluid, and a pump that sends the refrigerant condensed by the condenser to the steam generator, connected in a ring shape; a branch flow path connecting a branch point between the condenser and the pump in the circulation flow path and the first suction port, the branch flow path including an expander that reduces the pressure of the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant reduced in pressure by the expander through heat exchange with a cooled medium and supplies the refrigerant to the first ejector as the first suction flow; an auxiliary mechanism that draws in the refrigerant discharged from the first ejector and supplies the refrigerant to the condenser; Equipped with The auxiliary mechanism includes: an auxiliary flow path connecting a third portion of the circulation flow path between the pump and the steam generator and a portion of the circulation flow path between the first ejector and the condenser; a second ejector that is installed in the auxiliary flow path, introduces the refrigerant flowing through the auxiliary flow path from a second inlet as a second driving flow, mixes the refrigerant with a second suction flow discharged from the first discharge port and introduced from a second suction port, and discharges the mixed refrigerant from the second discharge port, The circulation flow path includes a portion that connects the first discharge port and the condenser without passing through the second ejector. Cooling system.

3. A control unit that switches between passing and blocking the coolant flowing through the auxiliary flow path. The cooling system of claim 1 or claim 2, comprising:

4. The auxiliary mechanism includes: a switching mechanism that is disposed between the third portion and the second ejector and that switches between passing and blocking the refrigerant in the auxiliary flow path, The control unit controls the switching mechanism. The cooling system of claim 3.

5. A temperature detector is provided for detecting a temperature of the cooling fluid, The control unit controls a state of the assist mechanism in response to the temperature detected by the temperature detection unit. The cooling system of claim 3 or claim 4.

6. A check valve is provided between a first portion of the circulation flow path, where the refrigerant discharged from the first ejector is sucked by the auxiliary mechanism, and a second portion of the circulation flow path, where the refrigerant is supplied from the auxiliary mechanism, to allow the refrigerant to pass from the first portion toward the second portion and to prevent the refrigerant from passing from the second portion toward the first portion. The cooling system according to any one of claims 1 to 5.

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