Cooling system

Abstract

To suppress deterioration of cooling capacity in a high-temperature environment.SOLUTION: A first circulation flow passage 11 in which a first refrigerant circulates includes a first steam generator 13, a first ejector 14, a first heat exchanger 30 and a first pump 16, and a first branch flow passage 12 branched from the first circulation flow passage 11 includes a first expander 17 and an evaporator 18. A second circulation flow passage 21 in which a second refrigerant circulates includes a second steam generator 23, a second ejector 24, a second heat exchanger 25 and a second pump 26, and a second branch flow passage 22 branched from the second circulation flow passage 21 includes a second expander 27 and the first heat exchanger 30. The first heat exchanger 30 condenses the first refrigerant and evaporates the second refrigerant by exchanging heat between the first refrigerant discharged from the first ejector 14 and the second refrigerant decompressed by the first expander 17.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, a cooling system using an ejector that mixes and discharges a suction flow generated by a driving flow with the driving flow has been proposed. For example, Patent Document 1 discloses a refrigeration cycle including a low-stage ejector and a high-stage ejector. The discharge flow from the low-stage ejector is sucked by the driving flow of the high-stage ejector. The refrigerant discharged from the high-stage ejector is condensed by a condenser.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a condenser that condenses a refrigerant, a cooling fluid such as cooling water or air is used, for example. For example, in a high-temperature environment such as in summer, the temperature of the cooling fluid rises, so the temperature of the refrigerant in the condenser rises, and as a result, the pressure of the discharge flow of the ejector (hereinafter referred to as "back pressure") may rise. When the back pressure rises, there is a problem that the flow rate of the suction flow sucked by the ejector decreases and the cooling capacity decreases. In view 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 Problems

[0005] A cooling system according to one aspect of the present invention includes a first vapor generator that evaporates a first refrigerant by heat exchange with a heat source fluid, a first ejector that introduces the first refrigerant evaporated in the first vapor generator as a first driving flow from a first inlet, mixes it with a first suction flow introduced from a first suction port, and discharges it from a first discharge port, a first heat exchanger that condenses the first refrigerant discharged from the first ejector by heat exchange with a second refrigerant, and a first pump that sends the first refrigerant condensed by the first heat exchanger to the first vapor generator, which are annularly connected to form a first circulation flow path, and a flow path that branches from a first branch point between the first heat exchanger and the first pump in the first circulation flow path, the flow path including a first expander that decompresses the first refrigerant supplied from the first heat exchanger, and a first branch flow path that supplies the first refrigerant to the first suction port via an evaporator that evaporates the first refrigerant decompressed by the first expander by heat exchange with a medium to be cooled, a second vapor generator that evaporates a second refrigerant by heat exchange with a heat source fluid, a second ejector that introduces the second refrigerant evaporated in the second vapor generator as a second driving flow from a second inlet, mixes it with a second suction flow introduced from a second suction port, and discharges it from a second discharge port, a second heat exchanger that condenses the second refrigerant discharged from the second ejector by heat exchange with a cooling fluid, and a second pump that sends the second refrigerant condensed by the second heat exchanger to the second vapor generator, which are annularly connected to form a second circulation flow path, and a flow path that branches from a second branch point between the second heat exchanger and the second pump in the second circulation flow path, the flow path including a second expander that decompresses the second refrigerant supplied from the second heat exchanger, and a second branch flow path that supplies the second refrigerant to the second suction port via the first heat exchanger that evaporates the second refrigerant decompressed by the second expander by heat exchange with the first refrigerant.

[0006] In the above aspect, the second refrigerant circulates through the second steam generator, the second ejector, the second heat exchanger, and the second pump in the above order, and the first refrigerant in the first circulation flow path is cooled by heat exchange with the second refrigerant sucked into the second ejector through the second branch flow path. Further, the first refrigerant circulates through the first steam generator, the first ejector, the first heat exchanger, and the first pump in the above order, and the medium to be cooled is cooled by heat exchange with the first refrigerant sucked into the first ejector through the first branch flow path. Two-stage cooling is realized: an operation of cooling the first refrigerant using the second refrigerant and the second ejector, and an operation of cooling the medium to be cooled using the cooled first refrigerant and the first ejector. Therefore, even in an environment where the cooling fluid becomes high temperature, the flow rate of the first suction flow of the first ejector is sufficiently ensured, and as a result, sufficient cooling capacity can be maintained.

[0007] In a preferred aspect of the present invention, the first refrigerant and the second refrigerant are different types of refrigerants. For example, the saturation temperature of the first refrigerant is lower than the saturation temperature of the second refrigerant. In the above aspect, since the first refrigerant and the second refrigerant are different types of refrigerants, the discharge efficiency of the first ejector and the second ejector is maintained at a high level in both high-temperature and low-temperature environments. Therefore, sufficient cooling capacity can be realized in both high-temperature and low-temperature environments.

[0008] In a preferred aspect of the present invention, the heat source fluid that evaporates the second refrigerant in the second steam generator is introduced into the first steam generator. According to the above aspect, since the heat source fluid is shared by the first steam generator and the second steam generator, an increase in the scale of the cooling system can be suppressed as compared with a configuration in which separate heat source fluids are supplied to the first steam generator and the second steam generator.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] FIG. 1 is a configuration diagram of a cooling system 100 according to an embodiment of the present invention. The cooling system 100 is a system for cooling a medium to be cooled Q3. The medium to be cooled Q3 is a medium for the purpose of cooling by the cooling system 100 and is a fluid such as, for example, water, oil, or air. As illustrated in FIG. 1, the cooling system 100 of the present embodiment includes a first system 10, a second system 20, and a first heat exchanger 30.

[0011] The first system 10 includes a first circulation flow path 11, a first branch flow path 12, a first steam generator 13, a first ejector 14, a first pump 16, a first expander 17, and an evaporator 18. A first refrigerant circulates in the first circulation flow path 11 and the first branch flow path 12. In the first circulation flow path 11, the first steam generator 13, the first ejector 14, the first heat exchanger 30, and the first pump 16 are installed in the above order. That is, the first circulation flow path 11 annularly connects the first steam generator 13, the first ejector 14, the first heat exchanger 30, and the first pump 16.

[0012] The second system 20 includes a second circulation flow path 21, a second branch flow path 22, a second steam generator 23, a second ejector 24, a second heat exchanger 25, a second pump 26, and a second expander 27. A second refrigerant circulates in the second circulation flow path 21 and the second branch flow path 22. In the second circulation flow path 21, the second steam generator 23, the second ejector 24, the second heat exchanger 25, and the second pump 26 are installed in the above order. That is, the second circulation flow path 21 annularly connects the second steam generator 23, the second ejector 24, the second heat exchanger 25, and the second pump 26.

[0013] The first heat exchanger 30 condenses the first refrigerant in the first circulation passage 11 and evaporates the second refrigerant in the second branch passage 22 by heat exchange between the gaseous-phase first refrigerant in the first circulation passage 11 and the liquid-phase second refrigerant in the second branch passage 22. As understood from the above description, in the cooling system 100 of the present embodiment, the first system 10 and the second system 20 are interconnected via the first heat exchanger 30. In other words, the first system 10 and the second system 20 share the first heat exchanger 30. Note that the first heat exchanger 30 may be regarded as an element of one of the first system 10 and the second system 20.

[0014] The flow paths of the first system 10 (the first circulation passage 11 and the first branch passage 12) and the flow paths of the second system 20 (the second circulation passage 21 and the second branch passage 22) are separate flow paths that do not communicate with each other. That is, the first refrigerant and the second refrigerant are not mixed. Therefore, the types of the first refrigerant and the second refrigerant are selected individually. In the present embodiment, the first refrigerant used in the first system 10 and the second refrigerant used in the second system 20 are different types of refrigerants. That is, the first refrigerant and the second refrigerant differ, for example, in composition or characteristics. Specifically, the saturation temperature (condensation temperature or evaporation temperature) of the second refrigerant is higher than the saturation temperature (condensation temperature or evaporation temperature) of the first refrigerant. That is, the saturation pressure of the second refrigerant is higher than the saturation pressure of the first refrigerant.

[0015] The warm water flow path 91 in FIG. 1 is a flow path that spans the first system 10 and the second system 20. Warm water Q1 is supplied as a heat source fluid to the warm water flow path 91. The warm water Q1 is, for example, waste warm water such as factory drainage or used cooling water. The first system 10 is located downstream of the second system 20 in the warm water flow path 91. Note that the warm water flow path 91 may be individually installed for each of the first system 10 and the second system 20. Each of the first system 10 and the second system 20 will be described in detail below.

[0016] [First System 10] First, the specific configuration of the first system 10 will be described. The first vapor generator 13 of the first system 10 is a heat exchanger (recovery device) that evaporates the first refrigerant by heat exchange between the hot water Q1 supplied to the hot water flow path 91 and the first refrigerant in the first circulation flow path 11.

[0017] The first ejector 14 includes a first inlet 14a, a first suction port 14b, and a first discharge port 14c. The gaseous first refrigerant sent out from the first vapor generator 13 is supplied to the first inlet 14a as the first driving flow X1. The first ejector 14 sucks the first refrigerant in the first branch flow path 12 as the first suction flow Y1 from the first suction port 14b due to the static pressure drop generated by the first driving flow X1. The first driving flow X1 supplied to the first inlet 14a and the first suction flow Y1 supplied to the first suction port 14b are mixed, and the mixed gaseous first refrigerant is pressurized by the diffuser and then discharged from the first discharge port 14c. As described above, the first ejector 14 introduces the first refrigerant evaporated in the first vapor generator 13 as the first driving flow X1 from the first inlet 14a, mixes it with the first suction flow Y1 introduced from the first suction port 14b, and discharges it from the first discharge port 14c.

[0018] The first heat exchanger 30 condenses the gaseous first refrigerant supplied from the first ejector 14. The first pump 16 is a liquid-phase pump that sends the liquid-phase first refrigerant condensed by the first heat exchanger 30 to the first vapor generator 13. The first refrigerant in the first circulation flow path 11 is pressurized by the first pump 16 to the driving pressure of the first ejector 14.

[0019] The first branch flow path 12 is a flow path that branches off from the first circulation flow path 11. That is, a part of the first refrigerant flowing through the first circulation flow path 11 is supplied to the first branch flow path 12. Specifically, the first branch flow path 12 connects the first branch point N1 between the first heat exchanger 30 and the first pump 16 in the first circulation flow path 11 and the first suction port 14b of the first ejector 14. That is, the first branch flow path 12 is a flow path that supplies the first refrigerant that becomes the first suction flow Y1 to the first ejector 14. The first expansion device 17 and the evaporator 18 are installed in the first branch flow path 12. The evaporator 18 is located between the first expansion device 17 and the first suction port 14b of the first ejector 14.

[0020] A part of the first refrigerant condensed by the first heat exchanger 30 is supplied to the first expansion device 17. The first expansion device 17 expands by reducing the pressure of the first refrigerant in the first branch flow path 12. For example, 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 first expansion device 17.

[0021] The evaporator 18 is a heat exchanger that evaporates the first refrigerant by heat exchange between the cooled medium Q3 supplied to the cooled flow path 93 and the liquid-phase refrigerant decompressed by the first expansion device 17. The gaseous first refrigerant generated by the evaporator 18 is sucked into the first suction port 14b of the first ejector 14 as the first suction flow Y1. The latent heat of the first refrigerant whose pressure has been reduced by suction from the first ejector 14 is used to cool the cooled medium Q3.

[0022] In the above configuration, the first refrigerant of the first system 10 circulates in the first circulation flow path 11 in the order of the first steam generator 13 → the first ejector 14 → the first heat exchanger 30 → the first pump 16 → the first steam generator 13. Then, the first refrigerant branched from the first circulation flow path 11 to the first branch flow path 12 is sucked into the first suction port 14b of the first ejector 14 via the first expander 17 and the evaporator 18. By the heat exchange between the first refrigerant in the evaporator 18, the coolant Q3 in the coolant flow path 93 is cooled. As understood from the above description, the first branch flow path 12 branches from the first branch point N1 between the first heat exchanger 30 and the first pump 16 in the first circulation flow path 11, and supplies the first refrigerant to the first suction port 14b via the first expander 17 and the evaporator 18.

[0023] [Second System 20] Next, the specific configuration of the second system 20 will be described. The second steam generator 23 of the second system 20 is a heat exchanger (recovery device) that evaporates the second refrigerant by heat exchange between the hot water Q1 supplied to the hot water flow path 91 and the second refrigerant in the second circulation flow path 21. The hot water Q1 whose temperature has decreased due to the heat exchange in the second steam generator 23 (that is, the hot water Q1 that has evaporated the second refrigerant) is supplied to the first steam generator 13 of the first system 10. That is, the temperature of the hot water Q1 in the first steam generator 13 is lower than the temperature of the hot water Q1 in the second steam generator 23.

[0024] The second ejector 24 includes a second inlet 24a, a second suction port 24b, and a second discharge port 24c. The vapor-phase second refrigerant sent from the second vapor generator 23 is supplied as a second driving flow X2 to the second inlet 24a. The second ejector 24 sucks the second refrigerant in the second branch flow path 22 as a second suction flow Y2 from the second suction port 24b due to the static pressure drop generated by the second driving flow X2. The second driving flow X2 supplied to the second inlet 24a and the second suction flow Y2 supplied to the second suction port 24b are mixed, and the mixed vapor-phase second refrigerant is pressurized by a diffuser and then discharged from the second discharge port 24c. As described above, the second ejector 24 introduces the second refrigerant evaporated in the second vapor generator 23 as the second driving flow X2 from the second inlet 24a, mixes it with the second suction flow Y2 introduced from the second suction port 24b, and discharges it from the second discharge port 24c.

[0025] The second heat exchanger 25 condenses the vapor-phase second refrigerant discharged from the second ejector 24. Specifically, the second heat exchanger 25 condenses the second refrigerant by heat exchange between the second refrigerant supplied from the second ejector 24 and the cooling fluid Q2 supplied to the heat dissipation flow path 92. The cooling fluid Q2 is, for example, low-temperature industrial water or cooling water supplied from a circulating cooling tower. The second refrigerant in the second circulation flow path 21 condenses by dissipating heat to the cooling fluid Q2.

[0026] The second pump 26 is a liquid-phase pump that sends the liquid-phase second refrigerant condensed by the second heat exchanger 25 to the second vapor generator 23. The second refrigerant in the second circulation flow path 21 is pressurized by the second pump 26 to the driving pressure of the second ejector 24.

[0027] The second branch flow path 22 is a flow path that branches off from the second circulation flow path 21. That is, a part of the second refrigerant flowing through the second circulation flow path 21 is supplied to the second branch flow path 22. Specifically, the second branch flow path 22 connects the second branch point N2 between the second heat exchanger 25 and the second pump 26 in the second circulation flow path 21 and the second suction port 24b of the second ejector 24. That is, the second branch flow path 22 is a flow path that supplies the second refrigerant that becomes the second suction flow Y2 to the second ejector 24. A second expander 27 and a first heat exchanger 30 are installed in the second branch flow path 22. The first heat exchanger 30 is located between the second expander 27 and the second suction port 24b of the second ejector 24.

[0028] A part of the second refrigerant condensed by the second heat exchanger 25 is supplied to the second expander 27. The second expander 27 expands by depressurizing the second refrigerant in the second branch flow path 22. For example, 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 tube is used as the second expander 27.

[0029] The first heat exchanger 30 is supplied with the first refrigerant discharged from the first ejector 14 via the first circulation flow path 11, and the second refrigerant depressurized by the second expander 27 is supplied via the second branch flow path 22. The first heat exchanger 30 condenses the first refrigerant and evaporates the second refrigerant by heat exchange between the gaseous first refrigerant discharged from the first ejector 14 and the liquid-phase second refrigerant supplied from the second expander 27. That is, the first heat exchanger 30 functions as a condenser that condenses the first refrigerant and an evaporator that evaporates the second refrigerant. The gaseous second refrigerant generated by the first heat exchanger 30 in the second branch flow path 22 is sucked into the second suction port 24b of the second ejector 24 as the second suction flow Y2. The latent heat of the second refrigerant whose pressure has been reduced by the suction from the second ejector 24 is used to cool the first refrigerant in the first circulation flow path 11.

[0030] In the above configuration, the second refrigerant of the second system 20 circulates in the second circulation flow path 21 in the order of the second steam generator 23 → the second ejector 24 → the second heat exchanger 25 → the second pump 26 → the second steam generator 23. Then, the second refrigerant branched from the second circulation flow path 21 to the second branch flow path 22 is sucked into the second suction port 24b of the second ejector 24 via the second expander 27 and the first heat exchanger 30. By the heat exchange with the second refrigerant in the first heat exchanger 30, the first refrigerant in the first circulation flow path 11 is cooled. As understood from the above description, the second branch flow path 22 branches from the second branch point N2 between the second heat exchanger 25 and the second pump 26 in the second circulation flow path 21, and is a flow path that supplies the second refrigerant to the second suction port 24b via the second expander 27 and the first heat exchanger 30.

[0031] Figure 2 is a P-h diagram related to the cooling system 100. The state of the first refrigerant in the first system 10 is illustrated by a solid line, and the state of the second refrigerant in the second system 20 is illustrated by a dashed line.

[0032] Due to the heat exchange in the first vapor generator 13, the state of the first refrigerant in the first circulation flow path 11 transitions from state a1 to state b1. In the process where the first ejector 14 mixes and discharges the first driving flow X1 and the first suction flow Y1, the state of the first refrigerant transitions from state b1 to state c1. The pressure P at state c1 corresponds to the back pressure of the first ejector 14. Due to the heat exchange (condensation) in the first heat exchanger 30, the state of the first refrigerant in the first circulation flow path 11 transitions from state c1 to state d1. Then, the portion of the first refrigerant in the first circulation flow path 11 that is supplied to the first pump 16 is pressurized by the first pump 16, and the state of the first refrigerant transitions from state d1 to the aforementioned state a1. On the other hand, the state of the first refrigerant supplied from the first circulation flow path 11 to the first branch flow path 12 transitions from state d1 to state e1 due to the pressure reduction in the first expander 17. The state of the first refrigerant after the pressure reduction transitions from state e1 to state f1 due to the heat exchange in the evaporator 18. The gaseous first refrigerant sent out from the evaporator 18 is sucked into the first ejector 14 as the first suction flow Y1, and the state of the first refrigerant transitions from state f1 to the aforementioned state c1. State c1 corresponds to the mixing of the first driving flow X1 and the first suction flow Y1 within the first ejector 14.

[0033] Due to the heat exchange in the second steam generator 23, the state of the second refrigerant in the second circulation flow path 21 transitions from state a2 to state b2. In the process where the second ejector 24 mixes and discharges the second driving flow X2 and the second suction flow Y2, the state of the second refrigerant transitions from state b2 to state c2. The pressure P in state c2 corresponds to the back pressure of the second ejector 24. Due to the condensation in the second heat exchanger 25, the state of the second refrigerant in the second circulation flow path 21 transitions from state c2 to state d2. Then, the portion of the second refrigerant in the second circulation flow path 21 that is supplied to the second pump 26 is pressurized by the second pump 26, and the state of the second refrigerant transitions from state d2 to the aforementioned state a2. On the other hand, the state of the second refrigerant supplied from the second circulation flow path 21 to the second branch flow path 22 transitions from state d2 to state e2 due to the pressure reduction in the second expander 27. The state of the second refrigerant after the pressure reduction transitions from state e2 to state f2 due to the heat exchange in the first heat exchanger 30. The gaseous second refrigerant sent out from the first heat exchanger 30 is sucked into the second ejector 24 as the second suction flow Y2, and the state of the second refrigerant transitions from state f2 to the aforementioned state c2. State c2 corresponds to the mixing of the second driving flow X2 and the second suction flow Y2 within the second ejector 24.

[0034] Figure 3 is a configuration diagram of a cooling system related to the comparative example. The comparative example is a configuration in which the second system 20 in the first embodiment is omitted and the first heat exchanger 30 is replaced with the second heat exchanger 25. In the comparative example, the first refrigerant in the first circulation flow path 11 is condensed by the heat exchange between the first refrigerant discharged from the first ejector 14 and the cooling fluid Q2 supplied to the heat dissipation flow path 92. Only the first refrigerant is used in the comparative example.

[0035] For example, in a high-temperature environment such as in summer, the temperature of the cooling fluid Q2 rises. In the comparative example, when the temperature of the cooling fluid Q2 rises, the condensation temperature of the first refrigerant rises, which may cause the pressure of the discharge flow of the first ejector 14 (i.e., the back pressure) to rise. When the back pressure of the first ejector 14 rises, the difference between the pressure of the first suction flow Y1 and the back pressure increases, so the flow rate of the first suction flow Y1 sucked into the first ejector 14 (i.e., the flow rate of the first refrigerant flowing through the first branch flow path 12) decreases. Therefore, in the comparative example, there is a problem that the ability to cool the medium to be cooled Q3 (hereinafter referred to as "cooling capacity") in a high-temperature environment decreases.

[0036] Note that if the pressure of the first driving flow X1 is increased, the flow rate of the first suction flow Y1 will increase. However, since the pressure of the first driving flow X1 depends on the temperature difference between the warm water Q1 in the first steam generator 13 and the first refrigerant in the first circulation flow path 11, it is practically difficult to sufficiently increase the pressure of the first driving flow X1. Also, a method of suppressing a decrease in the temperature of the warm water Q1 by increasing the flow rate of the warm water Q1 and increasing the pressure of the first driving flow X1 by increasing the evaporation temperature of the first refrigerant is also conceivable. However, since the power required for the pump that supplies the warm water Q1 to the warm water flow path 91 increases, there is a problem that the scale of the entire device or the cost required for cooling increases.

[0037] In contrast to the comparative example, in the first embodiment, the cooling system 100 is composed of a first system 10 and a second system 20. In the above configuration, the second refrigerant branched from the second circulation flow path 21 to the second branch flow path 22 is sucked into the second suction port 24b of the second ejector 24 via the second expander 27 and the first heat exchanger 30. The first refrigerant in the first circulation flow path 11 is cooled by heat exchange by the first heat exchanger 30. Then, the first refrigerant cooled by the second system 20 branches from the first circulation flow path 11 to the first branch flow path 12 and is sucked into the first suction port 14b of the first ejector 14 via the first expander 17 and the evaporator 18. The medium to be cooled Q3 in the flow path to be cooled 93 is cooled by heat exchange by the evaporator 18.

[0038] As described above, in the present embodiment, the medium to be cooled Q3 is cooled by heat exchange with the first refrigerant after being cooled by the second system 20. That is, the second system 20 uses the second refrigerant to Cooling cool the first refrigerant, and a two-stage cooling is realized, which includes the operation of cooling the first refrigerant by the second system 20 and the operation of cooling the medium to be cooled Q3 by the first system 10 using the first refrigerant cooled by the second system 20. By cooling the first refrigerant in the first circulation path 11, even in an environment where the cooling fluid Q2 is at a high temperature, the back pressure of the first ejector 14 is maintained at a low pressure. That is, the difference between the pressure of the first suction flow Y1 and the back pressure in the first ejector 14 is reduced. Therefore, even in a high-temperature environment, the flow rate of the first suction flow Y1 by the first ejector 14 is sufficiently ensured, and as a result, a sufficient cooling capacity can be maintained.

[0039] FIG. 4 is a graph showing the relationship between the temperature T and the discharge efficiency E of the ejector for each of the first refrigerant and the second refrigerant. In the proportional case where only the first refrigerant is used, in an environment where the cooling fluid Q2 is at a low temperature TL, the discharge efficiency E of the first ejector 14 is maintained at a high value E1. However, in the proportional case where only the first refrigerant is used, in an environment where the cooling fluid Q2 is at a high temperature TH, the discharge efficiency E of the first ejector 14 decreases to a value E2. Therefore, under proportional conditions, a sufficient cooling capacity cannot be achieved in an environment where the cooling fluid Q2 is at a high temperature TH.

[0040] In contrast to the comparative example, in the present embodiment, different types of a first refrigerant and a second refrigerant are used. Specifically, the saturation temperature of the second refrigerant is higher than the saturation temperature of the first refrigerant. For example, in a low-temperature environment such as winter, since the first refrigerant is maintained at the low temperature TL in FIG. 4, similarly to the comparative example, the discharge efficiency E of the first ejector 14 is maintained at a high value E1. On the other hand, as understood from FIG. 4, even in an environment where the cooling fluid Q2 is at the high temperature TH, the discharge efficiency E of the second ejector 24 is maintained at a high value E3. That is, in a high-temperature environment such as summer, the first refrigerant of the first system 10 is effectively cooled by the second ejector 24 operating with a high discharge efficiency E. As described above, in the present embodiment, since different types of the first refrigerant and the second refrigerant are used, the effect of suppressing a decrease in the cooling capacity in a high-temperature environment is particularly remarkable. However, the first refrigerant and the second refrigerant may be the same type of refrigerant.

[0041] Note that FIG. 8 of Patent Document 1 discloses a cooling system including a low-stage ejector and a high-stage ejector. The discharge flow from the low-stage ejector is sucked into the high-stage ejector. In contrast to the configuration of Patent Document 1, in the first embodiment, since the first system 10 including the first ejector 14 and the second system 20 including the second ejector 24 are connected via the first heat exchanger 30, it is significantly different from the configuration disclosed in Patent Document 1.

Explanation of Reference Numerals

[0042] 100... Cooling system, 10... First system, 11... First circulation flow path, 12... First branch flow path, 13... First steam generator, 14... First ejector, 14a... First inlet, 14b... First suction port, 14c... First discharge port, 16... First pump, 17... First expander, 18... Evaporator, 20... Second system, 21... Second circulation flow path, 22... Second branch flow path, 23... Second steam generator, 24... Second ejector, 24a... Second inlet, 24b... Second suction port, 24c... Second discharge port, 25... Second heat exchanger, 26... Second pump, 27... Second expander, 30... First heat exchanger, 91... Warm water flow path, 92... Heat dissipation flow path, 93... Flow path to be cooled.

Claims

1. A first vapor generator that evaporates a first refrigerant by heat exchange with a heat source fluid, a first ejector that introduces the first refrigerant evaporated in the first vapor generator as a first driving flow from a first inlet, mixes it with a first suction flow introduced from a first suction port, and discharges it from a first discharge port, a first heat exchanger that condenses the first refrigerant discharged from the first ejector by heat exchange between the first refrigerant and a second refrigerant of a different type from the first refrigerant, and a first pump that sends the first refrigerant condensed by the first heat exchanger to the first vapor generator, which are annularly connected to form a first circulation flow path, A flow path that branches from a first branch point between the first heat exchanger and the first pump in the first circulation flow path, a first expander that decompresses the first refrigerant supplied from the first heat exchanger, and a first refrigerant is supplied to the first suction port via an evaporator that evaporates the first refrigerant decompressed by the first expander by heat exchange with a medium to be cooled. A first branch flow path, A second vapor generator that evaporates a second refrigerant by heat exchange with a heat source fluid, a second ejector that introduces the second refrigerant evaporated in the second vapor generator as a second driving flow from a second inlet, mixes it with a second suction flow introduced from a second suction port, and discharges it from a second discharge port, a second heat exchanger that condenses the second refrigerant discharged from the second ejector by heat exchange with a cooling fluid, and a second pump that sends the second refrigerant condensed by the second heat exchanger to the second vapor generator, which are annularly connected to form a second circulation flow path, A flow path that branches from a second branch point between the second heat exchanger and the second pump in the second circulation flow path, a second expander that decompresses the second refrigerant supplied from the second heat exchanger, and the second refrigerant is supplied to the second suction port via the first heat exchanger that evaporates the second refrigerant decompressed by the second expander by heat exchange with the first refrigerant. A second branch flow path Comprising The heat source fluid that has evaporated the second refrigerant in the second vapor generator is introduced into the first vapor generator via a flow path extending between the second vapor generator and the first vapor generator. Cooling system.

2. A first vapor generator that evaporates a first refrigerant by heat exchange with a heat source fluid, a first ejector that introduces the first refrigerant evaporated in the first vapor generator as a first driving flow from a first inlet and mixes it with a first suction flow introduced from a first suction port and discharges it from a first discharge port, a first heat exchanger that condenses the first refrigerant discharged from the first ejector by heat exchange with a second refrigerant, and a first pump that sends the first refrigerant condensed by the first heat exchanger to the first vapor generator, which are annularly connected to form a first circulation flow path, A flow path that branches from a first branch point between the first heat exchanger and the first pump in the first circulation flow path, and includes a first expander that decompresses the first refrigerant supplied from the first heat exchanger, and an evaporator that evaporates the first refrigerant decompressed by the first expander by heat exchange with a medium to be cooled, and supplies the first refrigerant to the first suction port via a first branch flow path, A second vapor generator that evaporates a second refrigerant by heat exchange with a heat source fluid, a second ejector that introduces the second refrigerant evaporated in the second vapor generator as a second driving flow from a second inlet and mixes it with a second suction flow introduced from a second suction port and discharges it from a second discharge port, a second heat exchanger that condenses the second refrigerant discharged from the second ejector by heat exchange with a cooling fluid, and a second pump that sends the second refrigerant condensed by the second heat exchanger to the second vapor generator, which are annularly connected to form a second circulation flow path, A flow path that branches from a second branch point between the second heat exchanger and the second pump in the second circulation flow path, and includes a second expander that decompresses the second refrigerant supplied from the second heat exchanger, and the first heat exchanger that evaporates the second refrigerant decompressed by the second expander by heat exchange with the first refrigerant, and supplies the second refrigerant to the second suction port via a second branch flow path Comprising, The heat source fluid that has evaporated the second refrigerant in the second vapor generator is introduced into the first vapor generator via a flow path extending between the second vapor generator and the first vapor generator, The saturation temperature of the first refrigerant is lower than the saturation temperature of the second refrigerant Cooling system.

Images