Heat source system
The heat source system addresses temperature stratification issues by switching operating modes to maintain continuous low-temperature chilled water supply and rapid storage unit restoration, enhancing system resilience during power outages and restarts.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TAKENAKA CORP
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026112891000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a heat source system including a heat source unit for cooling cold water, a heat utilization unit for utilizing the cold heat of the cold water, a cold water storage unit having a pair of connection ports and capable of storing cold water in a form in which cold water passes from one connection port to the other connection port, a cold water circulation circuit in which cold water circulates, and control means for controlling the operation.
Background Art
[0002] There is known a heat source system for circulating and supplying cold water cooled by a heat source unit to a heat utilization unit such as an air conditioner for cooling an electronic device such as a computer or a water-cooled pipe of a server rack (see, for example, Patent Document 1). The heat source system described in Patent Document 1 includes a heat source unit (chiller) for cooling cold water, a heat utilization unit (server rack) for utilizing the cold heat of the cold water, and a cold water storage unit (low-temperature tank of a buffer tank) having an upper connection port and a lower connection port and capable of storing cold water in a form in which cold water passes in a downward cold water passing direction from the upper connection port to the lower connection port, and a cold water circulation circuit in which cold water circulates. When the heat source unit is operating normally, cold water cooled by the heat source unit (hereinafter sometimes referred to as "low-temperature cold water") passes through the cold water storage unit in the downward cold water passing direction and is then supplied to the heat utilization unit, and the cold water (hereinafter sometimes referred to as "high-temperature cold water") that has passed through the heat utilization unit and has been heated is returned to the heat source unit, and cold water is circulated in the cold water circulation circuit. In such a conventional heat source system, since cold water always passes through the cold water storage unit without staying, the state of the cold water storage unit can always be maintained in a state filled with low-temperature cold water (hereinafter sometimes referred to as "low-temperature cold water full state"). Therefore, for example, even when the operation of the heat source unit stops due to a power outage or the like and cooling of cold water becomes impossible, the low-temperature cold water stored in the cold water storage unit can be continuously supplied to the heat utilization unit while passing cold water through the cold water storage unit in the downward cold water passing direction.
Prior Art Documents
[0003] [Patent Document 1] Japanese Patent Publication No. 2014-220419 [Overview of the Initiative] [Problems that the invention aims to solve]
[0004] However, in the conventional heat source system described above, immediately after the cooling source unit starts operating and the cooling of chilled water resumes, when the low-temperature chilled water cooled by the cooling source unit passes through the chilled water storage unit in the same downward chilled water flow direction as when the cooling source unit stopped operating, the temperature stratification that was maintained when the cooling source unit stopped operating is temporarily broken. This results in a problem where the temperature of the chilled water flowing out of the chilled water storage unit and supplied to the chilling utilization unit temporarily becomes higher than the temperature of the low-temperature chilled water. Furthermore, the recovery time required for the chilled water storage unit to return to a state of being full of low-temperature chilled water and for the temperature of the chilled water flowing out of the chilled water storage unit and supplied to the chilling utilization unit to drop sufficiently becomes relatively long. Therefore, if, for example, the cooling source unit stops operating again due to a power outage during that recovery time, there is a problem that low-temperature chilled water cannot be properly supplied to the chilling utilization unit. In view of these circumstances, the main objective of the present invention is to provide a heat source system for circulating and supplying chilled water cooled in a cooling source unit to a cooling utilization unit, which enables the continued supply of low-temperature chilled water to the cooling utilization unit even when the operation of the cooling source unit stops, and also enables the rapid supply of low-temperature chilled water to the cooling utilization unit and the rapid filling of the chilled water storage unit when the operation of the cooling source unit is restarted. [Means for solving the problem]
[0005] The first characteristic configuration of the present invention is a chilled water circulation circuit in which chilled water is circulated, comprising: a cooling source unit for cooling chilled water; a cooling utilization unit that utilizes the cold energy of chilled water; and a chilled water storage unit having a pair of connection ports and capable of storing chilled water in a manner that allows chilled water to pass from one connection port to the other connection port. A heat source system comprising control means for controlling operation, As a driving mode, A first operating mode in which chilled water is circulated in the chilled water circulation circuit in such a manner that chilled water cooled in the chilled water source unit is supplied to the chilled water utilization unit after passing through the chilled water storage unit, and the chilled water that has passed through the chilled water utilization unit is returned to the chilled water source unit, A second operating mode in which chilled water is circulated in the chilled water circulation circuit in which chilled water is passed through the chilled water storage section in a predetermined first chilled water passage direction, chilled water flowing out of the chilled water storage section is supplied to the cooling energy utilization section, and chilled water that has passed through the cooling energy utilization section is returned to the chilled water storage section, The system has a third operating mode in which chilled water is circulated in the chilled water circulation circuit in such a manner that chilled water is passed through the chilled water storage section in a second chilled water passage direction opposite to the first chilled water passage direction, while chilled water cooled in the cooling source section is distributed and supplied to the cooling utilization section and the chilled water that has flowed out from the high-temperature side of the chilled water storage section, respectively, and chilled water is returned to the cooling source section. The control means is characterized by performing an operation stop operation mode switching process to switch the operating mode to the second operating mode when the cooling source unit stops operating, and performing an operation start operation mode switching process to temporarily switch the operating mode to the third operating mode and then to the first operating mode when the cooling source unit starts operating during operation in the second operating mode.
[0006] According to this configuration, under normal operating conditions when the cooling source is functioning correctly, the system operates in the first operating mode described above. Cold water cooled by the cooling source passes through the cold water storage section and is supplied to the cooling utilization section. High-temperature cold water, which has been heated after passing through the cooling utilization section, is returned to the cooling source section. In this manner, cold water is circulated through the cold water circulation circuit. As a result, cold water does not stagnate in the cold water storage section, and cold water always passes through it, thus maintaining the cold water storage section at a constant state of being full of cold water. When the cooling source unit stops operating, the operating mode is switched from the first operating mode to the second operating mode by executing the above-mentioned operation stop operating mode switching process. When cooling stops due to a power outage or the like, and the cooling source unit stops operating, making it impossible to cool the chilled water, the system operates in the second operating mode, and chilled water is circulated in the chilled water circulation circuit in such a way that chilled water passes through the chilled water storage unit in a predetermined first chilled water passage direction, and the low-temperature chilled water that flows out of the chilled water storage unit is supplied to the cooling energy utilization unit, while the high-temperature chilled water that has passed through the cooling energy utilization unit is returned to the chilled water storage unit. With the system operating in the second operating mode, chilled water is stored in the chilled water storage unit while forming a temperature stratification, with low-temperature chilled water present in the downstream portion in the first chilled water passage direction and high-temperature chilled water present in the upstream portion in the first chilled water passage direction. Therefore, the low-temperature chilled water stored in the downstream portion in the first chilled water passage direction of the chilled water storage unit can be continuously supplied to the cooling energy utilization unit.
[0007] Furthermore, upon the start of operation of the cooling source unit, the operation mode is temporarily switched from the second operation mode to the third operation mode by executing the operation start-up operation mode switching process described above. Then, operation is temporarily performed in the third operation mode, and chilled water is circulated in the chilled water circulation circuit in which chilled water is circulated in the chilled water storage unit in a second chilled water passage direction opposite to the first chilled water passage direction in the second operation mode, while chilled water cooled in the cooling source unit is distributed and supplied to the upstream part of the chilled water storage unit in the second chilled water passage direction, respectively, and chilled water that has passed through the chilled water utilization unit and chilled water that has flowed out from the downstream part of the chilled water storage unit in the second chilled water passage direction is returned to the cooling source unit. As a result, in the chilled water storage section, the low-temperature chilled water cooled in the cooling source section flows into the upstream section in the second chilled water passage direction, which corresponds to the downstream section in the first chilled water passage direction where low-temperature chilled water was present in the immediately preceding second operating mode. At the same time, the high-temperature chilled water that was present in the downstream section in the second chilled water passage direction, which corresponds to the upstream section in the first chilled water passage direction in the immediately preceding second operating mode, is returned to the cooling source section and cooled without being mixed with the low-temperature chilled water. Therefore, at least a portion of the high-temperature chilled water stored in the chilled water storage section can be quickly and effectively replaced with low-temperature chilled water cooled in the cooling source section without disrupting the temperature stratification formed in the chilled water storage section.
[0008] Furthermore, since the temperature stratification formed in the chilled water storage section is maintained during operation in the third operating mode, even if the operation of the cooling source section stops again during operation in the third operating mode, by switching the operating mode from the third operating mode to the second operating mode, as described above, the low-temperature chilled water stored in the downstream portion of the chilled water storage section in the first chilled water passage direction can be continuously supplied to the cooling utilization section while temperature stratification is formed in the chilled water storage section. Then, by executing the above-mentioned operation start-up operation mode switching process, at least a portion of the high-temperature chilled water stored in the chilled water storage section is replaced with low-temperature chilled water during operation in the third operation mode, and then the operation mode is switched from the third operation mode to the first operation mode. As a result, even when starting operation in the first operation mode, the chilled water storage section can be quickly maintained at full capacity with low-temperature chilled water by supplying the chilled water used in the chilled water utilization section after passing the low-temperature chilled water cooled in the chilled water source section through the chilled water storage section.
[0009] Accordingly, the present invention provides a heat source system for circulating and supplying chilled water cooled in a cooling source unit to a cooling utilization unit, which enables the continued supply of low-temperature chilled water to the cooling utilization unit even when the cooling source unit stops operating, and also provides a technology for quickly bringing the chilled water storage unit to a state of full low-temperature chilled water while appropriately supplying low-temperature chilled water to the cooling utilization unit when the cooling source unit restarts operating.
[0010] A second characteristic feature of the present invention is that, in the first operating mode, chilled water is passed through the chilled water storage section in the first chilled water passage direction.
[0011] According to this configuration, the direction of passage of chilled water in the chilled water storage section in the first operating mode and the direction of passage of chilled water in the chilled water storage section in the second operating mode are the same as the first chilled water passage direction. As a result, when the operating mode is switched from the first operating mode to the second operating mode by executing the operation mode switching process when the cooling source unit stops operating, there is no need to change the direction of passage of chilled water in the chilled water storage section. Therefore, the supply of low-temperature chilled water stored in the downstream part of the chilled water storage section in the first chilled water passage direction can be started quickly and appropriately to the cooling utilization unit.
[0012] A third characteristic configuration of the present invention is that the chilled water storage section has, as a pair of connection ports, an upper connection port provided on the upper side and a lower connection port provided below the upper connection port, The first cold water passage direction is a downward cold water passage direction in the cold water storage section, from the upper connection port to the lower connection port. The second cold water passage direction is an upward cold water passage direction in the cold water storage section, from the lower connection port to the upper connection port.
[0013] According to this configuration, the first chilled water passage direction in the chilled water storage section during the second operating mode is a downward chilled water passage direction from the upper connection port to the lower connection port, causing low-temperature chilled water to flow out of the lower connection port and high-temperature chilled water to flow in from the upper connection port. Furthermore, the second chilled water passage direction in the chilled water storage section during the third operating mode is an upward chilled water passage direction from the lower connection port to the upper connection port, causing low-temperature chilled water to flow in from the lower connection port and high-temperature chilled water to flow out from the upper connection port. Therefore, during operation in the second and third operating modes, the temperature stratification formed in the chilled water storage section is such that high-temperature chilled water exists in the upper part adjacent to the upper connection port, and low-temperature chilled water with a higher specific gravity than the high-temperature chilled water exists in the lower part adjacent to the lower connection port. Therefore, the temperature stratification formed in the chilled water storage section can be maintained in a more favorable state by also utilizing the difference in specific gravity between the high-temperature chilled water and the low-temperature chilled water.
[0014] A fourth feature configuration of the present invention is the inclusion of a power outage detection means for detecting the occurrence of a power outage in which the supply of power to the cooling source unit is stopped, The control means determines that the operation of the cooling / heating source unit has stopped when the power outage detection means detects the occurrence of a power outage, and then executes the operation stop operation mode switching process.
[0015] According to this configuration, when the power outage detection means detects the occurrence of a power outage, the control means determines that the operation of the cooling source unit has stopped and cooling of chilled water is no longer possible, and executes the operation stop operation mode switching process. Therefore, the operation mode can be switched to the second operation mode quickly and appropriately in response to the shutdown of the cooling source unit.
[0016] The fifth characteristic configuration of the present invention includes a full water detection means for detecting that the state of the cold water storage section is a low-temperature cold water full state in which the cold water storage section is filled with low-temperature cold water below a predetermined set temperature. When the control means executes the operation start-time operation mode switching process, when the full water detection means detects that the state is the low-temperature cold water full state during operation in the third operation mode, the operation mode is switched from the third operation mode to the first operation mode.
[0017] According to this configuration, when executing the operation start-time operation mode switching process along with the start of operation of the heat source section, after the operation in the third operation mode is performed until the state of the cold water storage section becomes a low-temperature cold water full state in which it is completely filled with low-temperature cold water, the operation mode is switched from the third operation mode to the first operation mode. Therefore, at the start of operation in the first operation mode, it is possible to immediately supply low-temperature cold water to the cold heat utilization section from immediately after the switching of the operation mode in a form in which low-temperature cold water is passed through the cold water storage section that is completely in the low-temperature cold water full state.
Brief Description of the Drawings
[0018] [Figure 1] Figure showing the configuration of the heat source system of this embodiment and the operation state in the first operation mode [Figure 2] Figure showing the configuration of the heat source system of this embodiment and the operation state in the second operation mode [Figure 3] Figure showing the configuration of the heat source system of this embodiment and the operation state in the third operation mode [Figure 4] Processing flowchart of operation mode switching control
Embodiments for Carrying Out the Invention
[0019] An embodiment of the heat source system according to the present invention will be described based on the drawings. As shown in Figures 1 to 3, the heat source system of this embodiment (hereinafter referred to as "this heat source system") comprises a chilled water circulation circuit 10 through which chilled water (Wa, Wb) circulates, and a control device 50 (an example of control means) that controls the operation.
[0020] The chilled water circulation circuit 10 is provided with a cooling source unit 2, a cooling utilization unit 3, and a chilled water storage unit 4. In this embodiment, an example is shown in which multiple cooling source units 2, cooling utilization units 3, and chilled water storage units 4 are arranged in parallel, but the number of these can be changed as appropriate. As will be described in detail later, the chilled water circulation circuit 10 receives relatively low-temperature chilled water Wa cooled by the cooling source unit 2 (hereinafter referred to as "low-temperature chilled water") and relatively high-temperature chilled water Wb heated by the cooling utilization unit 3 (hereinafter referred to as "high-temperature chilled water"). In Figures 1, 2, and 3, areas through which low-temperature chilled water Wa is flowing are shown with dark hatching, and areas through which high-temperature chilled water Wb is flowing are shown with light hatching. Also, in Figures 1, 2, and 3, open valves are shown in white, and closed valves are shown in black.
[0021] The cooling source unit 2 is composed of, for example, a chiller or a refrigeration device, and cools the high-temperature chilled water Wb that flows in from the pipeline 11 to generate low-temperature chilled water Wa, and then discharges the generated low-temperature chilled water Wa into the pipeline 12.
[0022] In each of the multiple cooling source units 2, the inlet pipes 11 into which the high-temperature chilled water Wb flows are connected to a common first header 21. Meanwhile, the outlet pipes 12 from which low-temperature chilled water Wa flows out of each of the multiple cooling source units 2 are connected to a common second header 22. Furthermore, each pipe 12 is equipped with a pump P1 capable of supplying water from the cooling source unit 2 to the second header 22. The pump P1 is operated and controlled by a control device 50.
[0023] The cooling and heat utilization unit 3 is composed of, for example, an air conditioning system for suitably cooling information processing equipment such as computers and other electronic devices, or water cooling piping for server racks. It is configured to utilize the cold energy of chilled water by raising the temperature of low-temperature chilled water Wa that flows in from the conduit 18 by consuming the cold energy it contains, generating high-temperature chilled water Wb, and then discharging the generated high-temperature chilled water Wb into the conduit 19.
[0024] In each of the multiple cooling units 3, the inlet pipes 18 into which the low-temperature chilled water Wa flows are merged as appropriate and then connected to a common third header 23. On the other hand, the outlet pipes 19 into which the high-temperature chilled water Wb flows out in each of the multiple cooling units 3 are merged as appropriate and then branched and connected to a first header 21. In addition, a pipe 30 is provided to connect the first header 21 and the second header 22. A shut-off valve 28 is provided at the connection point of the pipeline 19 to the first header 21, which can open and close each connection point. Similarly, a shut-off valve 29 is provided at the pipeline 30, which can open and close the pipeline 30. By opening and closing the shut-off valve 29 with the shut-off valve 28 open, the destination of the high-temperature chilled water Wb flowing from the outlet-side pipeline 19 of the multiple cooling / heat utilization units 3 can be switched between the first header 21 and the second header 22. That is, as shown in Figures 1 and 3, when the cooling / heat utilization unit 2 is operating and high-temperature chilled water Wb is flowing from the first header 21 to the pipeline 11 leading to the cooling / heat utilization unit 2, closing the shut-off valve 29 with the shut-off valve 28 at the connection point to the first header 21 open prevents the high-temperature chilled water Wb flowing from the outlet-side pipeline 19 of the multiple cooling / heat utilization units 3 into the first header 21 from flowing into the second header 22. Therefore, the destination of the high-temperature chilled water Wb is set to the first header 21. On the other hand, as shown in Figure 2, when the operation of the cooling source unit 2 is stopped and high-temperature chilled water Wb is not flowing out from the first header 21 to the pipeline 11 leading to the cooling source unit 2, opening the on-off valve 29 while the on-off valve 28 provided at the connection to the first header 21 is open causes the high-temperature chilled water Wb that has flowed into the first header 21 from the pipeline 19 on the outlet side of the multiple cooling utilization units 3 to flow into the second header 22 through the pipeline 30, thus setting the destination of the high-temperature chilled water Wb to the second header 22. The on-off valves 28 and 29 are controlled to open and close by the control device 50.
[0025] The chilled water storage section 4 is composed of a vertically elongated, sealed tank or the like, and has a pair of connection ports 4a and 4b, and is configured to store chilled water in a manner in which chilled water passes from one side of the pair of connection ports 4a and 4b to the other side. Furthermore, the chilled water storage section 4 has a pair of connection ports 4a and 4b, an upper connection port 4a located on the upper side and a lower connection port 4b located below it. In this embodiment, the upper connection port 4a is located at the upper end of the chilled water storage section 4, and the lower connection port 4b is located at the lower end.
[0026] A pipeline 14 leading to the first header 21 and a pipeline 15 leading to the second header 22 are connected to the upper connection port 4a of the chilled water storage section 4. In this embodiment, pipelines 14 and 15 are individually connected to the upper connection port 4a of the chilled water storage section 4, but pipelines 14 and 15 may also be combined and connected to the upper connection port 4a of the chilled water storage section 4. A shut-off valve 24 is provided at the connection point of the pipeline 14 to the upper connection port 4a of the chilled water storage section 4, which can open and close the connection point. A shut-off valve 25 is provided at the connection point of the pipeline 15 to the upper connection port 4a of the chilled water storage section 4, which can open and close the connection point. Furthermore, a pump P2 is provided in the pipeline 15 that can supply water from the second header 22 side to the shut-off valve 25 side. A pipeline 16 is provided that connects the section of pipeline 15 between pump P2 and on-off valve 25 to the third header 23, and this pipeline 16 is equipped with an on-off valve 26 that can open and close the pipeline 16. A pipeline 17 leading to the third header 23 is connected to the lower connection port 4b of the chilled water storage section 4. An on-off valve 27 capable of opening and closing the connection portion of the pipeline 17 to the lower connection port 4b of the chilled water storage section 4 is provided. The on / off valves 24, 25, 26, and 27 are controlled to open and close by the control device 50, and the pump P2 is controlled to operate by the control device 50.
[0027] As will be described in more detail later, the control device 50 controls the opening and closing of the on-off valves 24, 25, 26, and 27 and the operation of the pumps P1 and P2, thereby switching the direction of passage of chilled water in the chilled water storage section 4 between a downward chilled water passage direction Fd (an example of a first chilled water passage direction, see Figures 1 and 2), where chilled water flows in from the upper connection port 4a and flows out from the lower connection port 4b, and an upward chilled water passage direction Fu (an example of a second chilled water passage direction, see Figure 3), where chilled water flows in from the lower connection port 4b and flows out from the upper connection port 4a.
[0028] This heat source system is equipped with a power outage detection device 6 (an example of a power outage detection means) that detects the occurrence of a power outage in which the supply of power E to the cooling source unit 2 is stopped. The detection result of the power outage detection device 6 (power outage detection means) is input to the control device 50. When a power outage occurs, the operation of the cooling source unit 2 stops, making it impossible to cool the chilled water in the cooling source unit 2, and the operation of the pump P1 attached to the cooling source unit 2 also stops. On the other hand, while the cooling source unit 2 and pump P1 stop operating during the power outage, the other pumps P2, on-off valves 24, 25, 26, 27, 28, 29, and control device 50 are configured to continue operating using power supplied from an emergency power source (not shown).
[0029] This heat source system is equipped with a temperature sensor 7 in each chilled water storage section 4 that detects the temperature of the chilled water stored at the upper end. When the temperature detected by this temperature sensor 7 falls below a set temperature corresponding to the temperature of the low-temperature chilled water Wa, the chilled water storage section 4 is filled with low-temperature chilled water Wa, indicating a low-temperature chilled water full state. Therefore, this temperature sensor 7 functions as a full-water detection means that detects that the chilled water storage section 4 is filled with low-temperature chilled water Wa at or below a predetermined set temperature. The detection result of the temperature sensor 7 is input to the control device 50.
[0030] This heat source system has three operating modes, each with a different chilled water circulation state in the chilled water circulation circuit 10: a first operating mode (see Figure 1), a second operating mode (see Figure 2), and a third operating mode (see Figure 3). The details of each of these operating modes will be described below.
[0031] [First operating mode] Figure 1 shows the operating state in the first operating mode. As shown in Figure 1, the first operating mode is an operating mode in which chilled water Wa and Wb are circulated in the chilled water circulation circuit 10 in which low-temperature chilled water Wa cooled in the chilled water source unit 2 is supplied to the chilled water storage unit 4 and then to the chilled water utilization unit 3, and high-temperature chilled water Wb that has passed through the chilled water utilization unit 3 is returned to the chilled water source unit 2.
[0032] In the first operating mode, the control device 50 operates pumps P1 and P2, opening valves 25, 27, and 28, and closing valves 24, 26, and 29. Then, the low-temperature chilled water Wa cooled in the cooling source unit 2 flows through pipeline 12, the second header 22, and pipeline 15 in the order described, and flows into the chilled water storage unit 4 from the upper connection port 4a. Then, in the chilled water storage unit 4, as the low-temperature chilled water Wa flows in from the upper connection port 4a, the low-temperature chilled water Wa flows out from the lower connection port 4b, and the low-temperature chilled water Wa passes in a downward chilled water flow direction Fd from the upper connection port 4a to the lower connection port 4b. The low-temperature chilled water Wa that flows out from the lower connection port 4b of the chilled water storage unit 4 then flows through pipeline 17, the third header 23, and pipeline 18 in the order described, and is supplied to the cooling utilization unit 3. Furthermore, in the first operating mode, the high-temperature chilled water Wb, which has been heated by passing through the cooling utilization section 3 and consuming the stored cooling energy, is returned to the cooling source section 2 by flowing through the pipeline 19, the first header 21, and the pipeline 11 in the order described above. In the first operating mode, low-temperature chilled water Wa constantly passes through the chilled water storage section 4 without stagnating, so the chilled water storage section 4 is always maintained in a state of being full of low-temperature chilled water Wa at or below the set temperature.
[0033] [Second operating mode] Figure 2 shows the operating state in the second operating mode. As shown in Figure 2, the second operating mode is an operating mode in which chilled water Wa and Wb are circulated in the chilled water circulation circuit 10 in the same downward chilled water passage direction Fd as in the first operating mode, while the low-temperature chilled water Wa that flows out of the chilled water storage section 4 is supplied to the cold energy utilization section 3, and the high-temperature chilled water Wb that has passed through the cold energy utilization section 3 is returned to the chilled water storage section 4. Further details will be provided later, but in the second operating mode, the cooling source unit 2 and pump P1 are shut down. In Figure 2, these cooling source unit 2 and pump P1 are shown with dashed lines to indicate that they are in a shut-down state.
[0034] In the second operating mode, with the cooling source unit 2 and pump P1 stopped, the control device 50 activates pump P2, opening valves 25, 27, 28, and 29, and closing valves 24 and 26. In other words, comparing the open / closed state of each valve in the second operating mode with that of the first operating mode described above, the only difference is that valve 29, which was closed in the first operating mode, is open in the second operating mode, while the other valves 24, 25, 26, 27, and 28 are in the same state in both the first and second operating modes. As a result, in the chilled water storage unit 4, low-temperature chilled water Wa is present in the lower part, which is the downstream part in the downward chilled water passage direction Fd, and high-temperature chilled water Wb is present in the upper part, which is the upstream part in the downward chilled water passage direction Fd, and chilled water Wa and Wb are stored while forming a temperature stratification. Then, while the temperature stratification formed in the chilled water storage section 4 is maintained, the low-temperature chilled water Wa present in the lower part of the chilled water storage section 4 flows out from the lower connection port 4b, and the flowing low-temperature chilled water Wa is supplied to the cooling utilization section 3 by flowing through the pipeline 17, the third header 23, and the pipeline 18 in the order described above. Furthermore, in the second operating mode, the high-temperature chilled water Wb, which has been heated by passing through the cooling utilization section 3 and consuming the stored cooling energy, flows through the pipeline 19, the first header 21, the pipeline 30, the second header 22, and the pipeline 15 in the order described above, and flows into the upper part of the chilled water storage section 4 from the upper connection port 4a. Although a detailed explanation is omitted, a known configuration can be adopted for the upper connection port 4a that allows the high-temperature chilled water Wb to flow into the upper part of the chilled water storage section 4, in order to minimize disruption to the temperature stratification formed in the chilled water storage section 4.
[0035] In the second operating mode, the temperature stratification formed in the chilled water storage section 4 is such that high-temperature chilled water Wb is present in the upper part adjacent to the upper connection port 4a (the upstream part in the downward chilled water passage direction Fd), and low-temperature chilled water Wa, which has a higher specific gravity than the high-temperature chilled water Wb, is present in the lower part adjacent to the lower connection port 4b (the downstream part in the downward chilled water passage direction Fd). Therefore, the temperature stratification formed in the chilled water storage section 4 is maintained in a more favorable state by utilizing the difference in specific gravity between the high-temperature chilled water Wb and the low-temperature chilled water Wa. In the second operating mode, in the chilled water storage section 4, low-temperature chilled water Wa flows out from the lower part and high-temperature chilled water Wb flows into the upper part, so that chilled water Wa and Wb are stored while forming a temperature stratification, and the low-temperature chilled water Wa stored in the lower part, which is the downstream part in the downward chilled water passage direction Fd in the chilled water storage section 4, is continuously supplied to the cold energy utilization section 3. Furthermore, as low-temperature chilled water Wa is supplied from the chilled water storage section 4 to the cold energy utilization section 3, the amount of low-temperature chilled water Wa stored in the chilled water storage section 4 decreases, causing the boundary layer between the region where low-temperature chilled water Wa exists and the region where high-temperature chilled water Wb exists to gradually descend.
[0036] [Third operating mode] Figure 3 shows the operating state in the third operating mode. As shown in Figure 3, the third operating mode is an operating mode in which chilled water Wa and Wb are circulated in the chilled water circulation circuit 10 in a manner in which chilled water Wa and Wb are passed through the chilled water storage section 4 in an upward chilled water passage direction Fu opposite to the downward chilled water passage direction Fd, while the low-temperature chilled water Wa cooled in the cooling heat source section 2 is distributed and supplied to the cooling heat utilization section 3 and the chilled water storage section 4, respectively, and the high-temperature chilled water Wb that has passed through the cooling heat utilization section 3 and the high-temperature chilled water Wb that has flowed out from the upper connection port 4a, which is the high-temperature side of the chilled water storage section 4, are returned to the cooling heat source section 2.
[0037] In the third operating mode, the control device 50 operates pumps P1 and P2, opening valves 24, 26, 27, and 28, and closing valves 25 and 29. As a result, in the chilled water storage section 4, low-temperature chilled water Wa is present in the lower part, which is the upstream part in the upward chilled water passage direction Fu, and high-temperature chilled water Wb is present in the upper part, which is the downstream part in the upward chilled water passage direction Fu, thus forming a temperature stratification as chilled water Wa and Wb are stored. With the temperature stratification formed in the chilled water storage section 4 maintained, the low-temperature chilled water Wa cooled in the cooling source section 2 is supplied to the cooling utilization section 3. That is, the low-temperature chilled water Wa cooled in the cooling source section 2 flows through pipeline 12, the second header 22, pipeline 15, and pipeline 16 in the order described above and is supplied to the third header 23. Then, of the low-temperature chilled water Wa supplied to the third header 23, a portion flows through the pipeline 18 and is supplied to the cooling utilization section 3, while the remainder flows through the pipeline 17 and flows into the lower part of the chilled water storage section 4 from the lower connection port 4b. Although a detailed explanation is omitted, a known configuration can be adopted for the lower connection port 4b that allows the low-temperature chilled water Wa to flow into the lower part of the chilled water storage section 4, in order to minimize disruption to the temperature stratification formed in the chilled water storage section 4.
[0038] Furthermore, in the third operating mode, the high-temperature chilled water Wb present in the upper part of the chilled water storage section 4 flows out from the upper connection port 4a, and this outflowing high-temperature chilled water Wb flows through the pipeline 14, the first header 21, and the pipeline 11 in the order described, and is returned to the cooling source section 2. Therefore, in the third operating mode, the temperature stratification formed in the chilled water storage section 4 is similar to that in the second operating mode, with high-temperature chilled water Wb present in the upper part adjacent to the upper connection port 4a (the downstream part in the upward chilled water flow direction Fu), and low-temperature chilled water Wa, which has a higher specific gravity than the high-temperature chilled water Wb, present in the lower part adjacent to the lower connection port 4b (the upstream part in the upward chilled water flow direction Fu). On the other hand, the high-temperature chilled water Wb that has been heated up by passing through the cooling utilization section 3 and consuming the stored cooling energy is also returned to the cooling source section 2 by flowing through the pipeline 19, the first header 21, and the pipeline 11 in the order described.
[0039] In the third operating mode, in the chilled water storage section 4, low-temperature chilled water Wa flows into the lower section and high-temperature chilled water Wb flows out from the upper section, so that chilled water Wa and Wb are stored while forming a temperature stratification, and the low-temperature chilled water Wa cooled in the cooling source section 2 is continuously supplied to the cooling utilization section 3. Furthermore, as low-temperature chilled water Wa is supplied from the cooling source unit 2 to the chilled water storage unit 4, the amount of low-temperature chilled water Wa stored in the chilled water storage unit 4 increases. As a result, the boundary layer between the region where low-temperature chilled water Wa exists and the region where high-temperature chilled water Wb exists gradually rises, and thereafter, the chilled water storage unit 4 becomes a low-temperature chilled water full state, filled with low-temperature chilled water Wa below the set temperature.
[0040] [Operating mode switching control] The control device 50 performs operation mode switching control to switch the operation mode between the first operation mode (see Figure 1), the second operation mode (see Figure 2), and the third operation mode (see Figure 3) as described above, based on the operating state of the cooling source unit 2 and the chilled water storage state of the chilled water storage unit 4. Furthermore, as will be described in detail later, the control device 50 is configured to perform predetermined operation mode switching processing when operation stops and operation mode switching processing when operation starts during operation mode switching control. The details of the operation mode switching control performed by the control device 50 will be explained below with reference to the flowchart shown in Figure 4.
[0041] First, it is determined whether or not the cooling / heating source unit 2 is stopped (Step #1). Specifically, if a power outage is detected by the power outage detection device 6, it is determined that the cooling / heating source unit 2 is stopped (Yes in Step #1). Conversely, if a power outage is not detected by the power outage detection device 6 (power outage detection means), it is determined that the cooling / heating source unit 2 is operating (No in Step #1).
[0042] When it is determined that the cooling source unit 2 is operating (No in step #1), it is determined whether the chilled water storage unit 4 is in a low-temperature chilled water full state, where it is filled with low-temperature chilled water Wa (step #2). The determination of whether the chilled water storage unit 4 is in a low-temperature chilled water full state is made by determining whether the temperature of the chilled water stored in the upper part of the chilled water storage unit 4, as detected by the temperature sensor 7, is below the set temperature. That is, if the temperature detected by the temperature sensor 7 is below the set temperature, it is determined that the chilled water is in a low-temperature chilled water full state (Yes in step #2), and conversely, if the temperature detected by the temperature sensor 7 is above the set temperature, it is determined that the chilled water is not in a low-temperature chilled water full state (No in step #2).
[0043] If it is determined in step #1 that the cooling source unit 2 is operating (No in step #1), and if it is determined in step #2 that the chilled water storage unit 4 is full of low-temperature chilled water (Yes in step #2), the operating mode is set to the first operating mode (see Figure 1) (step #3).
[0044] When the operating mode is set to the first operating mode and operation is performed in this first operating mode, as described above, as shown in Figure 1, the low-temperature chilled water Wa cooled in the cooling source unit 2 is supplied to the cooling utilization unit 3 after passing through the chilled water storage unit 4, and the high-temperature chilled water Wb that has passed through the cooling utilization unit 3 returns to the cooling source unit 2, so that chilled water Wa and Wb circulate in the chilled water circulation circuit 10. As a result, chilled water Wa and Wb do not stagnate in the chilled water storage unit 4, and low-temperature chilled water Wa always passes through it, so the chilled water storage unit 4 can always be kept full of low-temperature chilled water.
[0045] If it is determined in step #1 that the cooling source unit 2 has stopped operating (Yes in step #1), the operating mode is set to the second operating mode (see Figure 2) (step #5). In other words, in the operation mode switching control, the control device 50 performs an operation stop operation mode switching process that switches the operation mode to the second operation mode when the cooling / heating source unit 2 stops operating.
[0046] Then, by executing the operation mode switching process when the system stops, the operation mode is switched to the second operation mode. When the system operates in this second operation mode, as described above, as shown in Figure 2, chilled water Wa and Wb pass through the chilled water storage section 4 in the downward chilled water passage direction Fd. Low-temperature chilled water Wa that flows out of the chilled water storage section 4 is supplied to the cold energy utilization section 3, and high-temperature chilled water Wb that passes through the cold energy utilization section 3 returns to the chilled water storage section 4. In this way, chilled water Wa and Wb circulate in the chilled water circulation circuit 10. This allows low-temperature chilled water Wa stored in the lower part of the chilled water storage section 4, which is the downstream part in the downward chilled water passage direction Fd, to be continuously supplied to the cold energy utilization section 3. Furthermore, when the operating mode is switched from the first operating mode (see Figure 1) to the second operating mode (see Figure 2) by executing the operating mode switching process when the system stops operating, it is only necessary to open the on-off valve 29, which was closed in the first operating mode, in the second operating mode while maintaining the open / closed states of the other on-off valves 24, 25, 26, 27, and 28, so the configuration for executing the operating mode switching process when the system stops operating due to a power outage or the like can be simplified.
[0047] If it is determined in step #1 that the cooling source unit 2 is operating (No. in step #1), and if it is determined in step #2 that the chilled water storage unit 4 is not in a low-temperature chilled water full state (No. in step #2), the operating mode is set to the third operating mode (see Figure 3) (step #4). Furthermore, during operation in the first operating mode (see Figure 1) described above, the chilled water storage unit 4 is always in a state of being full of low-temperature chilled water. Therefore, the determination that the chilled water storage unit 4 is not in a state of being full of low-temperature chilled water (No in step #2) is made when the operation of the cooling source unit 2 begins after the operation in the second operating mode (see Figure 2) has just been performed and the amount of low-temperature chilled water Wa stored in the chilled water storage unit 4 has decreased, and it is determined in step #1 that the cooling source unit 2 is operating (No in step #1). Also, when operation in the third operating mode (see Figure 3) is performed and the amount of low-temperature chilled water Wa stored in the chilled water storage unit 4 increases and the state of the chilled water storage unit 4 becomes full of low-temperature chilled water, it is determined in step #2 that the state of the chilled water storage unit 4 is full of low-temperature chilled water (Yes in step #2), and the operating mode is switched to the first operating mode (see Figure 1). In other words, in the operation mode switching control, the control device 50 performs an operation start operation mode switching process that temporarily switches the operation mode to the third operation mode when the cooling source unit 2 starts operating during operation in the second operation mode, and then switches back to the first operation mode.
[0048] Then, by executing the operation mode switching process at the start of operation, the operation mode is temporarily switched from the second operation mode to the third operation mode. When operation is performed in the third operation mode, as described above, as shown in Figure 3, chilled water Wa and Wb pass through the chilled water storage section 4 in the upward chilled water passage direction Fu, opposite to the downward chilled water passage direction Fd. The low-temperature chilled water Wa cooled in the cooling source section 2 is distributed and supplied to the cooling utilization section 3 and the chilled water storage section 4, respectively. At the same time, the high-temperature chilled water Wb that has passed through the cooling utilization section 3 and the high-temperature chilled water Wb that has flowed out from the upper connection port 4a, which is the high-temperature side of the chilled water storage section 4, return to the cooling source section 2. In this manner, chilled water Wa and Wb circulate in the chilled water circulation circuit 10. As a result, in the chilled water storage section 4, the low-temperature chilled water Wa cooled by the cooling source section 2 flows into the lower section, which is the upstream section in the upward chilled water passage direction Fu, corresponding to the downstream section in the downward chilled water passage direction Fd where the low-temperature chilled water Wa was present in the immediately preceding second operating mode (see Figure 2). At the same time, the high-temperature chilled water Wb that was present in the upper section, which is the downstream section in the upward chilled water passage direction Fu, corresponding to the upstream section in the downward chilled water passage direction Fd in the immediately preceding second operating mode (see Figure 2), is returned to the cooling source section 2 and cooled without being mixed with the low-temperature chilled water Wa. Therefore, at least a portion of the high-temperature chilled water Wb stored in the chilled water storage section 4 can be quickly and suitably replaced with the low-temperature chilled water Wa cooled by the cooling source section 2 without disrupting the temperature stratification formed in the chilled water storage section 4.
[0049] Furthermore, since the temperature stratification formed in the chilled water storage section 4 is maintained during operation in the third operating mode, even if the operation of the cooling source section 2 stops again during operation in the third operating mode, the operation of the cooling source section 2 is determined to have stopped in step #1 (Yes in step #1), and the operating mode is switched from the third operating mode (see Figure 3) to the second operating mode (see Figure 2) (step #5). As a result, as described above, while temperature stratification is formed in the chilled water storage section 4, the low-temperature chilled water Wa stored in the lower part, which is the downstream part in the downward chilled water passage direction Fd of the chilled water storage section 4, can be continuously supplied to the cooling utilization section 3. Then, after the operation mode switching process at the start of operation is executed and the operation is performed in the third operating mode (see Figure 3), the high-temperature chilled water Wb stored in the chilled water storage unit 4 is replaced with low-temperature chilled water Wa. In step #2, it is determined that the chilled water storage unit 4 is full of low-temperature chilled water (Yes in step #2), and the operating mode is switched from the third operating mode (see Figure 3) to the first operating mode (see Figure 1) (step #3). As a result, even when starting operation in the first operating mode, as shown in Figure 1, the low-temperature chilled water Wa cooled in the cooling source unit 2 can be supplied to the cooling utilization unit 3 after passing through the chilled water storage unit 4, which is now completely full of low-temperature chilled water.
[0050] [Another embodiment] Other embodiments of the present invention will now be described. Note that the configurations of each embodiment described below are not limited to being applied individually, but can also be applied in combination with the configurations of other embodiments.
[0051] (1) In the above embodiment, in the first operating mode, the chilled water storage section 4 is configured to pass low-temperature chilled water Wa in a downward chilled water passage direction Fd from the upper connection port 4a to the lower connection port 4b, as shown in Figure 1. However, in the first operating mode, the chilled water storage section 4 may also be configured to pass low-temperature chilled water Wa in an upward chilled water passage direction Fu from the lower connection port 4b to the upper connection port 4a. Even if low-temperature chilled water Wa is passed in an upward chilled water passage direction Fu in the first operating mode, the chilled water storage section 4 can be maintained in a state of being full of low-temperature chilled water.
[0052] (2) In the above embodiment, the chilled water storage section 4 is configured to store chilled water Wa and high-temperature chilled water Wb while forming a temperature stratification using the difference in specific gravity between the chilled water Wa and the chilled water Wb. However, it is also possible to configure the storage of chilled water Wa and high-temperature chilled water Wb by providing a partition wall or the like that separates the region where chilled water Wa is stored from the region where high-temperature chilled water Wb is stored, for example, while allowing chilled water to flow from one side to the other. In this configuration, the lower connection port 4b corresponds to a connection port leading to the region where chilled water Wa is stored, and the upper connection port 4a corresponds to a connection port leading to the region where high-temperature chilled water Wb is stored. Furthermore, in the above embodiment, the chilled water storage section 4 is configured to store chilled water Wa and chilled water Wb while forming a temperature stratification using the difference in specific gravity between the chilled water Wa and chilled water Wb. In this configuration, the upper connection port 4a is provided at the upper end and the lower connection port 4b is provided at the lower end. However, the locations of these upper and lower connection ports 4a and 4b can be appropriately changed, provided that the lower connection port 4b is located lower than the upper connection port 4a.
[0053] (3) In the above embodiment, a power outage detection device 6 is provided and the control device 50 is configured to determine whether or not the operation of the cooling source unit 2 has stopped using the detection result of the power outage detection device 6. However, the control device 50 may also be configured to directly monitor the operating state of the cooling source unit 2 and determine whether or not the operation of the cooling source unit 2 has stopped, without using the detection result of the power outage detection device 6.
[0054] (4) In the above embodiment, when the operation mode switching process is executed at the start of operation to temporarily set the operation mode to the third operation mode (see Figure 3), the system is configured to switch the operation mode to the first operation mode (see Figure 1) when it is detected that the chilled water storage unit 4 is full of low-temperature chilled water during operation in the third operation mode (see Figure 3). However, for example, the system may be configured to operate in the third operation mode for a certain period of time, and to switch the operation mode to the first operation mode (see Figure 1) before the chilled water storage unit 4 is completely full of low-temperature chilled water during operation in the third operation mode (see Figure 3).
[0055] (5) In the above embodiment, the on-off valve 29 provided in the conduit 30 connecting the first header 21 and the second header 22 is configured to be open in the second operating mode (see Figure 2) and closed in the first operating mode (see Figure 1) and the third operating mode (see Figure 3). However, the embodiment is not limited to this, and for example, the on-off valve 29 can also be configured to be open (i.e., always open) in the first and third operating modes as well. In this case, in the first operating mode, the low-temperature chilled water Wa that flows from the cooling source unit 2 through the pipeline 12 to the second header 22 is divided into two parts: one that flows through the pipeline 15 to the chilled water storage unit 4 from the upper connection port 4a, and another that flows through the pipeline 30 to the first header 21 and merges with the high-temperature chilled water Wb that returns to the cooling source unit 2. On the other hand, in the third operating mode, the low-temperature chilled water Wa that flows from the cooling source unit 2 through the pipeline 12 to the second header 22 is divided into two parts: one that flows through the pipelines 15 and 16 to the third header 23, and another that flows through the pipeline 30 to the first header 21 and merges with the high-temperature chilled water Wb that returns to the cooling source unit 2. In other words, the pipeline 30 connecting the first header 21 and the second header 22 functions as a constant bypass circuit for the low-temperature chilled water Wa in both the first and third operating modes. Furthermore, by adopting a configuration in which the on-off valve 29 is always open regardless of the operating mode, the number of on-off valve operations required when switching operating modes can be reduced, further simplifying the configuration. For example, since the open / closed states of each on-off valve 24, 25, 26, 27, 28, and 29 are the same in the first operating mode and the second operating mode, when switching the operating mode from the first operating mode to the second operating mode during a power outage, it is not necessary to change the open / closed states of each on-off valve 24, 25, 26, 27, 28, and 29, thus simplifying the configuration. [Explanation of Symbols]
[0056] 2 Cold and heat source 3 Cold and heat utilization section 4. Cold water storage section 4a Upper connection port (connection port) 4b Lower connection port (connection port) 6. Power outage detection device (power outage detection means) 7. Temperature sensor (water level detection means) 10 Chilled water circulation circuit 50 Control device (control means) E-power Fd downward cold water passage direction (first cold water passage direction) Fu Upward cold water passage direction (second cold water passage direction) Wa Low temperature cold water (cold water) Wb High temperature cold water (cold water)
Claims
1. A chilled water circulation circuit is provided, comprising a chilling source unit for cooling chilled water, a chilling utilization unit that utilizes the chilled energy of the chilled water, and a chilled water storage unit having a pair of connection ports through which chilled water can be stored in a manner that allows chilled water to pass from one connection port to the other. A heat source system comprising control means for controlling operation, As a driving mode, A first operating mode in which chilled water is circulated in the chilled water circulation circuit in such a manner that chilled water cooled in the chilled water source unit is supplied to the chilled water utilization unit after passing through the chilled water storage unit, and the chilled water that has passed through the chilled water utilization unit is returned to the chilled water source unit, A second operating mode in which chilled water is circulated in the chilled water circulation circuit in such a manner that chilled water is passed through the chilled water storage section in a predetermined first chilled water passage direction, the chilled water flowing out of the chilled water storage section is supplied to the cold energy utilization section, and the chilled water that has passed through the cold energy utilization section is returned to the chilled water storage section, The system has a third operating mode in which chilled water is circulated in the chilled water circulation circuit in such a manner that chilled water is passed through the chilled water storage section in a second chilled water passage direction opposite to the first chilled water passage direction, while chilled water cooled in the cooling source section is distributed and supplied to the cooling utilization section and the chilled water that has flowed out from the high-temperature side of the chilled water storage section, respectively, and chilled water is returned to the cooling source section. A heat source system in which the control means performs an operation stop operation mode switching process to switch the operating mode to the second operating mode when the cooling / heat source unit stops operating, and an operation start operation mode switching process to temporarily switch the operating mode to the third operating mode and then to the first operating mode when the cooling / heat source unit starts operating during operation in the second operating mode.
2. The heat source system according to claim 1, wherein in the first operating mode, chilled water is passed through the chilled water storage section in the first chilled water passage direction.
3. The chilled water storage section has, as a pair of connection ports, an upper connection port provided on the upper side and a lower connection port provided below the upper connection port. The first cold water passage direction is a downward cold water passage direction in the cold water storage section, from the upper connection port to the lower connection port. The heat source system according to claim 1 or 2, wherein the second chilled water passage direction is an upward chilled water passage direction in the chilled water storage section, from the lower connection port to the upper connection port.
4. The system includes a power outage detection means for detecting the occurrence of a power outage that stops the supply of power to the cooling source unit, The heat source system according to claim 1 or 2, wherein the control means determines that the operation of the cooling / heating source unit has stopped when the power outage detection means detects the occurrence of a power outage and executes the operation stop operation mode switching process.
5. The chilled water storage section is equipped with a full-water detection means that detects when it is filled with chilled water at a temperature below a predetermined set temperature. The heat source system according to claim 1 or 2, wherein the control means, when performing the operation start operation mode switching process, switches the operation mode from the third operation mode to the first operation mode when the full water level detection means detects that the low-temperature chilled water level is full during operation in the third operation mode.