JP4817073B2 - Cooling system and method using free cooling - Google Patents

Description

  The present invention relates to a cooling system using free cooling that saves energy in a cooling means provided in a circulation path of cold water flowing in a load.

  Factories that require a cold source throughout the year, such as semiconductor manufacturing factories, require more power for the cold source, and energy saving is desired. Therefore, attempts have been made to save energy by applying free cooling, which uses cold heat from the cooling tower for air conditioning, without operating the refrigerator at low temperatures such as in winter, to the cold heat source of the aforementioned factory.

  A cooling system including a conventional free cooling system is shown in FIG. A conventional cooling system 1 includes a refrigerator 2, a cooling tower 3 for a refrigerator, a free cooling tower 4, and a cold water tank 5 for storing cold water. The cold water is produced at the lowest temperature among the necessary temperatures by the refrigerator 2, and is once stored in the cold water tank 5. The cold water tank 5 supplies each load 7 with a pump 6. At this time, since the cold water set temperature differs for each load, the temperature of the cold water is adjusted by a heat exchanger (not shown) provided for each load. Further, the free cooling cooling tower 4 is operated in a free cooling based on information such as a weather forecast according to the judgment of the person in charge of the equipment in the winter when the outside air temperature falls.

  However, since the conventional cooling system 1 manufactured the cold water with the lowest temperature for all the cold water, the COP of the refrigerator 2 (coefficient of performance: a value representing the cooling / heating capacity kW per 1 kW of power consumption) deteriorated, and many There is a problem of consuming energy. In addition, since the set temperature of the cold water differs depending on the load, it is necessary to adjust the temperature with a heat exchanger after producing the cold water with the lowest temperature, resulting in inefficiency.

As a cooling system for solving this problem, there is a system disclosed in Japanese Patent Laid-Open No. 2003-121024 (Patent Document 1). According to Patent Document 1, a refrigerator and a pipe are arranged for each cold water temperature, the cold water temperature is increased, an INV turbo refrigerator is employed, and the cooling water temperature is lowered due to the integration of the cooling tower for the refrigerator. Energy saving is achieved by improving COP and controlling flow rate. In this case, free cooling is performed by exchanging heat between the cooling water cooled by the cooling tower and the cooling water without providing a dedicated cooling tower. Further, according to Patent Literature 2, a cold heat source facility is disclosed that increases the use period of free cooling and enhances the energy saving effect.
Japanese Patent Laid-Open No. 2003-121024 JP 2004-132651 A

However, in the cold water circulation path according to Patent Document 1, the flow rate of the cooling water may be limited. The reason for this is that the cooling water temperature cannot be set below the set temperature due to restrictions on the refrigerator side, and the cooling water temperature is adjusted to bypass the return of the cooling water and mixed with the cooling water cooled in the cooling tower. Yes. However, if the temperature difference between the cooling water temperature generated in the cooling tower and the set temperature of the cooling water is small, the flow rate toward the cooling tower is likely to be small, and the amount of cooling water cooled in the cooling tower is limited and free cooling is performed. It cannot be used effectively. In Patent Document 2, it is effective for a single load, but when applied to a plurality of loads having different chilled water set temperatures, a cooling tower is attached for each load, and the operation efficiency may deteriorate. There is.
Accordingly, an object of the present invention is to improve the energy saving of a refrigerator by operating a free cooling cooling tower for a long period of time in order to improve the above-mentioned problems of the prior art.

The cooling system using free cooling according to the present invention includes a load and a plurality of chilled water circulation paths for circulating the chilled water for each load having different chilled water set temperatures. The chilled water circulation path includes a free cooling cooling tower that cools the chilled water in the return side pipe and returns the chilled water to the return side pipe of the second chilled water circulation path that is lower than the chilled water set temperature of the first chilled water circulation path. A pipe directly connecting the return side pipe of the circulation path and the outgoing side pipe of the first cold water circulation path, and the cold water cooled by the free cooling cooling tower based on the outside air wet bulb temperature is returned to the second cold water circulation path Control means is provided for returning to the side pipe and cooling with the refrigerator, and supplying the cold water in the return side pipe of the second cold water circulation path to the forward side pipe of the first cold water circulation path.
In this case, the cooling tower of the refrigerator and the free cooling cooling tower may be integrated.

  Further, the cooling method using free cooling according to the present invention cools chilled water flowing through the return side piping of the first chilled water circulation path among the load and the chilled water circulation path of the refrigerator divided into a plurality of chilled water set temperatures of the load. Then, the chilled water cooled by the return side piping of the first chilled water circulation path based on the outside air wet bulb temperature is returned to the return side piping of the second chilled water circulation path lower than the chilled water set temperature of the first chilled water circulation path. It cools with a refrigerator and the cold water of the return side piping of the said 2nd cold water circulation path is supplied to the outgoing side piping of the said 1st cold water circulation path.

  According to the present invention configured as described above, a part of the chilled water in the return side pipe is diverted to the free cooling cooling tower by the on-off valve and cooled, and returned to the return side pipe again to be merged with the remaining chilled water. The temperature can be controlled. When the temperature of the chilled water after the temperature adjustment is the chilled water set temperature, the chilled water is bypassed from the return side pipe to the forward side pipe before the refrigerator on the chilled water circulation path. For this reason, cold water can be cooled only by a free cooling cooling tower regardless of a refrigerator, and the operating cost of the cold water cooling means can be reduced. Further, since the cooled cold water is not supplied to the refrigerator, the operating load of the pump on the return side pipe can be reduced.

  According to the present invention, among the plurality of circulation paths formed for each chilled water set temperature, the return side pipe of the second circulation path having a low chilled water set temperature is connected to the forward side pipe of the first circulation path having a high set temperature. Therefore, there is no need to cool with a refrigerator attached on the circulation path of the outgoing side piping of the first circulation path, and the operation cost can be reduced by stopping the refrigerator.

  According to the present invention, a cooling tower is formed by integrating a cooling tower for a plurality of loads with different chilled water set temperatures and a free cooling cooling tower, and the cooling tower is used for a freezer and a cooling tower according to the outside air wet bulb temperature. It is switched for. For this reason, the free cooling cooling tower can be operated for a long time, energy saving of the cooling means can be achieved, and the initial cost can be suppressed.

Embodiments of a cooling system using free cooling and a method thereof according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing a schematic configuration of a cooling system using free cooling according to the first embodiment. The cooling system 10 using free cooling according to the present invention is configured to include a plurality of cold water circulation paths 14 for attaching cold water chillers 20 flowing through a load 12 and circulating cold water as shown in FIG.

  As an example, the load 12 of the present invention includes three loads, that is, a device cooling load 12a, a sensible heat load 12b, and an outside air load 12c for each set temperature. The apparatus cooling load 12a is for cooling the heat generated from the production apparatus that operates. The sensible heat load 12b is due to sensible heat, and the heat generated in the production equipment that causes the room temperature of the clean room to rise and fall, heat radiated into the clean room, heat transfer from the building outer wall, solar radiation from the window, indoor lighting equipment It is intended to cool the temperature in the clean room that has risen due to heat generated by the human body, outside air, etc. The outside air load 12c means what is necessary for cooling and controlling the amount of heat (temperature, humidity) of outside air taken into the clean room for ventilation.

  As an example, in this embodiment, the cooling water set temperature of each load 12 is set to 17 degrees (for high temperature) as the apparatus cooling load 12a, 12 degrees (for medium temperature) as the sensible heat load 12b, and 7 degrees (for low temperature) as the outside air load 12c. This will be described below.

  The cold water circulation path 14 connects the cold water outlet of the load 12 and the cold water inlet of the refrigerator 20, connects the cold water outlet of the refrigerator 20 and the cold water inlet of the load 12, and connects between the load 12 and the refrigerator 20. Cool water is circulated in

  In the cold water circulation path 14, the direction in which the cold water from the load 12 flows into the refrigerator 20 is a return side pipe 16, and the direction in which the cold water cooled by the refrigerator 20 is sent to the load 12 is an outgoing side pipe 18. The chilled water circulation path 14 according to the present embodiment uses the apparatus cooling load 12a as the high-temperature chilled water circulation path 14c (C) and the sensible heat load 12b as the medium-temperature chilled water circulation path 14b (B) for each chilled water set temperature of the load 12. The outside air load 12c is a low-temperature chilled water circulation path 14a (A).

  A refrigerator cooling tower 40 is connected to the chilled water refrigerator 20 attached to each of the circulation paths A, B, and C. In the present embodiment, for three refrigerators 20, three cooling towers 40 connected in parallel are connected to the respective refrigerators 20 in parallel with each of the circulation paths A, B, C. Is forming.

  The cooling water circulation path 42 connects the cooling water discharge port of the refrigerator 20 and the cooling water inlet of the refrigerator cooling tower 40, and connects the cooling water discharge port of the refrigerator cooling tower 40 and the cooling water inlet of the refrigerator 20. The cooling water is circulated between the refrigerator 20 and the refrigerator cooling tower 40.

  The cooling water circulation path 42 uses the return side piping 44 as the direction in which the cooling water from the refrigerator 20 flows into the cooling tower 40 for the refrigerator, and sends the cooling water cooled by the cooling tower 40 to the refrigerator 20. The forward piping 46 is used. A pump 48 is attached to a pipe line before the refrigerator 20 in the cooling water outlet side pipe 46. Further, a bypass pipe 51 is provided to connect the cooling water return side pipe 44 and the forward side pipe 46 between the refrigerator cooling tower 40 and the pump 48, and a three-way valve 53 is attached to the connection port with the forward side pipe 46. ing.

  On the other hand, a free cooling cooling tower 30 is attached to the cold water return side pipe 16. The free cooling cooling tower 30 connects the cold water inflow pipe 32 to the load 12 side of the cold water return side pipe 16, connects the cold water discharge pipe 34 to the refrigerator 20 side of the cold water return side pipe 16, and returns. The cold water flowing through the side pipe 16 is bypassed.

  The free cooling cooling tower 30 performs heat exchange between cold water and outside air, and reduces the cooling burden of heat exchange of the refrigerator 20. As an example, the free cooling cooling tower 30 may be a hermetic cooling tower.

  A valve 36 serving as an on-off valve is provided at a connection point between the cold water inflow pipe 32 flowing into the free cooling cooling tower 30 and the cold water return side pipe 16. For example, a three-way valve can be used as the valve 36. The valve 36 allows a part of the cold water flowing through the return side pipe 16 to flow into the free cooling cooling tower 30. The valve 36 can adjust the flow rate of the cold water flowing to the free cooling cooling tower 30.

  A pump 37 is attached to the return side pipe 16 so that cold water flows from the load 12 toward the refrigerator 20. Further, a bypass pipe 38 directly connecting the return side pipe 16 of the load 12 and the forward side pipe 18 is provided in the return side pipe 16 in front of the refrigerator 20. A valve 39 that controls the entry and exit of cold water is mounted on the bypass pipe 38.

  The control means 50 is connected to the valves 36a to 36c attached to the return pipes 16a to 16c of the cold water, the free cooling cooling tower 30, and the valves 39a to 39c of the bypass pipes 38a to 38c. The control means 50 is connected to the return side cold water temperature sensors 52a to 52c for measuring the cold water temperature of the cold water return side pipes 16a to 16c and the outside air wet bulb temperature sensor 56 for measuring the outside air wet bulb temperature. Based on this, the cooling temperature of the cold water is controlled.

  A method of operating the cooling system using free cooling with the above configuration will be described below. FIG. 2 is an operation flowchart of the cooling system according to the present invention. The cooling system 10 forms circulation paths A, B, and C for each set temperature of the load 12, and includes a free cooling cooling tower 30 in each cold water circulation path 14. First, the outside air wet bulb temperature around the cooling system 10 is measured by the outside air wet bulb temperature sensor 56 (S100). The measured value of the outside wet bulb temperature is sent to the control means 50.

  The control means 50 compares the predetermined cold water set temperatures (17 degrees, 12 degrees, and 7 degrees) for each load. As a result, when the temperature of the outside wet bulb can cool the cold water of the return side pipe 16 of each circulation path by the free cooling cooling tower 30, the valve 36 attached to the return side pipe 16 is opened, and the free cooling cooling tower 30 is supplied with cold water. Inflow of a part of. A part of the cold water that has flowed in is exchanged in the free cooling cooling tower 30 between the outside air and the cold water to cool the cold water. The cooled cold water is discharged from the free cooling cooling tower 30 to the return side pipe 16.

  Next, the cold water temperature (free cooling cooling tower outlet temperature) of the return side pipe into which the cold water cooled by the free cooling cooling tower 30 flows is measured by the return side cold water temperature sensor 52 (S110). Then, the cold water temperature of the return pipe is compared with the cold water set temperature of the cold water circulation path (S120).

  As a result, when the chilled water temperature of the return side pipe is equal to or lower than the chilled water set temperature, the valve 39 of the bypass pipe 38 provided on the inlet side of the chiller 20 on the chilled water circulation path is opened, and the chilled water is directly passed through the refrigerator 20 Is allowed to flow into the outward piping 18 (S130). The operation flow shown in S100 to S130 is a case of winter operation. For example, when the outdoor air wet bulb temperature is 4 degrees, from any cold water set temperature (17 degrees, 12 degrees, 7 degrees) of the circulation paths A, B, and C. Also lower. At this time, the chilled water is supercooled in the circulation path A at the set temperature of 17 degrees. Therefore, the cold water temperature after the cold water cooled by the free cooling cooling tower 30 flows into the return side pipe 16 is measured, and when the measured value is too lower than the cold water set temperature, the valve 36 supplies the free cooling cooling tower 30 to the free cooling cooling tower 30. The amount of cold water to be cooled is reduced by adjusting the flow rate of cold water to be introduced, and the measured value of the return side cold water temperature sensor is controlled to be a cold water set temperature of 17 degrees.

  On the other hand, in the comparison between the cold water return side temperature and the cold water set temperature in S120, when the cold water temperature of the return side pipe is higher than the cold water set temperature, the following operation is performed. The cold water flowing out from the free cooling cooling tower 30 is compared with the cold water temperature discharged from the load (S140). As a result, when the cold water flowing out from the free cooling cooling tower 30 is lower than the cold water temperature discharged from the load, the operation is performed to send the cold water to the refrigerator 20 (S150). The operation flow shown in S100 to S150 is a case of an intermediate period operation. For example, when the outdoor wet bulb temperature is 15 degrees and the cold water temperature cooled by the free cooling cooling tower is also about 15 degrees, the cold water setting of the circulation path C is set. The temperature is lower than the temperature (17 degrees), but is higher than the set temperature of the circulation paths A and B. At this time, the cold water cooled by the free cooling cooling tower is lower than the cold water temperature of 17 degrees discharged from the load of the circulation path B. Therefore, the cooling water is cooled by the free cooling cooling tower 30 in the circulation path C, and the cooling water is directly flowed into the refrigerator 20 without flowing into the free cooling cooling tower 30 in the circulation path A. In the circulation path B, the cold water is allowed to flow into the free cooling cooling tower 30 and the cold water cooled by the free cooling cooling tower 30 is supplied to the refrigerator 20. Accordingly, in the circulation path B, the cooling water is cooled by the free cooling cooling tower 30, thereby reducing the burden of cooling the cold water by the refrigerator 20.

  Further, in the comparison between the chilled water temperature of the return side piping in S140 and the chilled water temperature discharged from the load, when the chilled water return side temperature is higher than the chilled water temperature discharged from the load, that is, when the chilled water cannot be cooled by the free cooling cooling tower. Supplies the cold water directly to the refrigerator 20 without passing through the free cooling cooling tower 30 to cool the cold water (S160). The operation flow shown in S100 to S160 is for summer operation.

Next, a second embodiment of the present invention will be described with reference to FIG. As shown in the figure, the cooling system 10a of the present invention and the configuration different from the first embodiment are a pipe connecting the return side pipe 16a of the circulation path A (low temperature cold water) and the forward side pipe 18b of the circulation path B (medium temperature cold water). 60a is formed to form a pipe 60b that connects the return side pipe 16b of the circulation path B (medium temperature cold water) and the forward side pipe 18c of the circulation path C (high temperature cold water), and is attached to each circulation path in the first embodiment. This is the point that a free cooling cooling tower 30a in which cooling towers for cooling are integrated is provided. Other constituent elements are the same as those in the first embodiment, and the same reference numerals are given and detailed description thereof is omitted.
The pipe 60 includes a valve 62 capable of arbitrarily adjusting the flow rate of the cold water in the middle of the pipe and a pump 64 for flowing the cold water from the cold water return side pipe 16 toward the forward side pipe 18.

  Further, valves 66a and 66b capable of arbitrarily adjusting the flow rate of the cold water are mounted on the outgoing side pipes 18b and 18c where the cold water refrigerators 20b and 20c and the pipes 60a and 60b are connected. Further, valves 66c and 66d capable of arbitrarily adjusting the flow rate of the cold water are mounted on the return side pipes 16a and 16b where the refrigerators 20a and 20b and the pipes 60a and 60b are connected.

  Further, valves 66e, 66f and 66g capable of arbitrarily adjusting the amount of cold water are respectively mounted on the cold water discharge side pipe 67 of the integrated free cooling cooling tower 30a and the return side pipes 16a to 16c of the respective cold water circulation paths. The control means 50 is connected to the free cooling cooling tower 30a, the valve 36, the valve 62, and the valve 66, and measures a chilled water temperature of the chilled water return side pipes 16a to 16c, an unillustrated return side chilled water temperature sensor, and an outside air wet bulb temperature. Is connected to an outdoor wet bulb temperature sensor 56, and the cooling temperature of the cold water is controlled based on each set temperature.

  A cooling method according to the second embodiment having the above configuration will be described below. FIG. 4 is a diagram showing the relationship between the outside air temperature and the outside air humidity. FIG. 5 is an explanatory diagram of operation switching of the cooling system based on the outside air wet bulb temperature. In FIG. 4, the horizontal axis represents the outside air temperature (degrees), the vertical axis represents the outside air humidity (%), and the outside air wet bulb temperatures T1, T2, and T3 are arbitrarily set as T1> T2> T3 from the high temperature side. The range above T1 is a, the outside air wet bulb temperature T1> T2 is b, the outside air bulb temperature T2> T3 is c, and the outside air bulb temperature T3 is below d.

  FIG. 5A shows a case where the outside air wet bulb temperature is equal to or higher than T1. When the outdoor wet bulb temperature sensor measures the outdoor wet bulb temperature and the measured temperature is T1 or higher, for example, 22 degrees or higher, the cold water discharged from each load 12 has a cold water temperature of 22 degrees, 17 degrees, and 12 degrees, respectively. Even if cold water is passed through the free cooling cooling tower 30a, it cannot be cooled. Therefore, the control means closes the supply of cold water to the free cooling cooling tower 30a with the valve 36 provided on the return side piping 16c of the cold water circulation path 14c, and stops the operation of the free cooling cooling tower 30a. The cold water from each load 12 is directly supplied to the refrigerators 20a to 20c to be cooled, and the cold water cooled to each cold water set temperature is supplied to the outgoing pipes 18a to 18c and returned to each load 12.

  FIG.5 (b) has shown the case where external air wet bulb temperature is T2 or more and T1 or less. When the outside wet bulb temperature is T2 or more and T1 or less, for example, 20 degrees, the cold water temperature discharged from the apparatus cooling load 12a is 22 degrees, and the free cooling cooling tower 30a can cool the cold water from the apparatus cooling load 12a. it can. Therefore, only the cold water in the return side pipe 16c of the cold water circulation path 14c is cooled by the free cooling cooling tower 30a. That is, the control means opens the free cooling cooling tower 30a side with the valve 36 of the return side pipe 16c of the cold water circulation path 14c, and operates the pump of the return side pipe 16c to supply the cold water to the free cooling cooling tower 30a to make a detour. Then, the chilled water cooled by the free cooling cooling tower 30a is reintroduced into the return side pipe 16c. At this time, the valve 66f between the discharge port of the free cooling cooling tower 30a and the return side pipe 16b and the valve 66e of the return side pipe 16a are closed. Cold water having a chilled water temperature of about 20 degrees is introduced into the refrigerator 20c and cooled to a chilled water set temperature of 17 degrees. The chilled water cooled by the refrigerator 20c is introduced into the outward piping 18c and returned to the apparatus cooling load 12a. Thereby, since the cold water is previously cooled to the outside wet bulb temperature by the free cooling cooling tower 30a, the burden of the cold water cooling by the refrigerator 20c can be reduced. The other chilled water circulation paths 14b and 14a perform normal cooling by the refrigerators 20b and 20a as in FIG.

  FIG. 5C shows a case where the outside air wet bulb temperature is T3 or more and T2 or less. When the outside wet bulb temperature is T3 or more and T2 or less, for example, 15 degrees, the cold water temperature discharged from the apparatus cooling load 12a is 22 degrees, and the free cooling cooling tower 30a can cool the cold water from the apparatus cooling load 12a. it can. Therefore, the cold water in the return side pipe 16c of the cold water circulation path 14c is cooled by the free cooling cooling tower 30a and introduced into the return side pipe 16b. That is, the control means opens the free cooling cooling tower 30a side with the valve 36 of the return side pipe 16c of the cold water circulation path 14c. Further, the valve 66g between the discharge port of the free cooling cooling tower 30a and the return side pipe 16c and the valve 66e of the third return side pipe 16a are closed, and the valve 66f of the return side pipe 16b is opened. The pump of the return side pipe 16b is operated to supply cold water to the free cooling cooling tower 30a to make a detour. And the cold water after cooling by the free cooling cooling tower 30a is introduce | transduced into the return side piping 16b. Cold water having a cold water temperature of around 15 degrees is introduced into the refrigerator 20b and cooled to a cold water set temperature of 12 degrees. The chilled water cooled by the refrigerator 20b is introduced into the outward piping 18b and returned to the load 12b.

  At this time, the operation of the refrigerator 20c in the cold water circulation path 14c is stopped, the valve 62 of the pipe 60b connecting the return side pipe 16b of the cold water circulation path 14b and the forward side pipe 18c of the cold water circulation path 14c is opened, and the pump 64 is used. The chilled water having a chilled water temperature of 17 degrees discharged from the sensible heat load 12b is directly introduced into the outward piping 18c of the apparatus cooling load 12a.

  Thereby, the cold water of the return side pipe 16c of the cold water circulation path 14c can be cooled by the free cooling cooling tower 30a, and the cold water of the forward side pipe 18c can be cascaded from the second return side pipe 16b of the cold water circulation path 14b. The operation of the refrigerator 20c in the circulation path 14c can be stopped. Moreover, since the cold water is cooled to the ambient air wet bulb temperature of about 15 degrees by the free cooling cooling tower 30a in advance, the burden of the cold water cooling by the refrigerator 20b can be reduced. The other chilled water circulation path 14a performs normal cooling by the refrigerator 20a as in FIG.

  FIG. 5D shows a case where the outside air wet bulb temperature is T3 or less. When the outside wet bulb temperature is T3 or less, for example, 10 degrees, the cold water temperature discharged from the apparatus cooling load 12a is 22 degrees, and the cold water from the apparatus cooling load 12a can be cooled by the free cooling cooling tower 30a. Therefore, the cold water in the return side pipe 16c of the cold water circulation path 14c is cooled by the free cooling cooling tower 30a and introduced into the third return side pipe 16a. That is, it opens to the free cooling cooling tower 30a side by the valve 36 of the return side pipe 16c of the cold water circulation path 14c. Further, the valve 66g between the discharge port of the free cooling cooling tower 30a and the first return side pipe 16c and the valve 66f of the second return side pipe 16b are closed, and the valve 66e of the third return side pipe 16a is opened. The pump of the 3rd return side piping 16a is operated, and cold water is supplied to the free cooling cooling tower 30a, and is detoured. And the cold water after cooling with the free cooling cooling tower 30a is introduce | transduced into the return side piping 16a. Cold water having a chilled water temperature of about 10 degrees is introduced into the refrigerator 20a and cooled to a chilled water set temperature of 10 degrees. The chilled water cooled by the refrigerator 20a is introduced into the outward piping 18a and returned to the load 12c.

  At this time, the operations of the refrigerator 20c in the cold water circulation path 14c and the refrigerator 20b in the cold water circulation path 14b are stopped. Then, the valve 62 of the pipe 60b connecting the return side pipe 16b of the chilled water circulation path 14b and the forward side pipe 18c of the chilled water circulation path 14c is opened, and chilled water having a chilled water temperature of 17 degrees discharged from the sensible heat load 12b by the pump 64. Is directly introduced into the forward piping 18c of the apparatus cooling load 12a.

  Further, the valve 62 of the pipe 60a connecting the return side pipe 16a of the chilled water circulation path 14a and the forward side pipe 18b of the chilled water circulation path 14b is opened, and chilled water having a chilled water temperature of 12 degrees discharged from the outside air load 12c by the pump 64 is opened. It is introduced directly into the outward piping 18b of the sensible heat load 12b.

  Thus, the chilled water in the return side piping 16c of the chilled water circulation path 14c can be cooled by the free cooling cooling tower 30a, and the chilled water in the outgoing side piping 18c can be cascaded from the return side piping 16b of the chilled water circulation path 14b. The operation of the refrigerator 20c of 14c can be stopped. The cold water in the outgoing side pipe 18b can be cascaded from the return side pipe 16a of the cold water circulation path 14a, and the operation of the refrigerator 20b in the cold water circulation path 14b can be stopped.

Moreover, since the cold water is cooled to the ambient air wet bulb temperature of about 10 degrees by the free cooling cooling tower 30a in advance, the burden of the cold water cooling by the refrigerator 20a can be reduced.
The operation of the cooling system may be switched using the cold water temperature cooled by the free cooling cooling tower 30a instead of the outside air wet bulb temperature.

  As described above, the cooling system 10a according to the second embodiment integrates the free cooling cooling tower 30a, and cool water circulation paths 14a and 14b that return the cooled cold water according to the outside air wet bulb temperature or the outlet temperature of the free cooling cooling tower 30a. , 14c. In the chilled water circulation path for introducing the chilled water cooled by the free cooling cooling tower 30a, the chilled water circulation path in which the chilled water in the return side pipe discharged from the load is set higher than the chilled water set temperature of the chilled water circulation path. It is introduced in the side piping. For example, chilled water from the return side piping of the medium temperature chilled water circulation path is cascaded by introducing it to the outgoing side piping of the high temperature chilled water circulation path, so there is no need to cool the chilled water in the high temperature chilled water circulation path with the refrigerator. Operation can be stopped. In addition, chilled water from the return pipe of the low temperature chilled water circulation path is introduced into the outgoing pipe of the intermediate temperature chilled water circulation path, and chilled water from the return pipe of the intermediate temperature chilled water circulation path is introduced into the outgoing pipe of the high temperature chilled water circulation path. Cascading. For this reason, it is not necessary to cool the cold water in the high-temperature cold water circulation path and the medium-temperature cold water circulation path with the refrigerator, and the operation of the two-line refrigerator can be stopped.

  FIG. 6 shows a cooling system using free cooling according to the third embodiment. As shown in the drawing, the cooling system 10b of the present invention is different from the cooling system 10a of the second embodiment in that a cooling tower 70 in which the refrigerator cooling tower 40 and the free cooling cooling tower 30 are integrated is provided. The other components are the same as those in the second embodiment, and the same reference numerals are given and detailed description thereof is omitted.

  In this embodiment, the cooling tower 70 serves as a free cooling cooling tower and a cooling tower for a refrigerator, and in this embodiment, the inlets and outlets of each of the six cooling towers are connected in parallel. A plurality of pairs (two pairs in this embodiment) of a pair of valves 73a, 73b, 74a, and 74b are attached to the pipes 71 and 72 that connect the inlet and the outlet. And the circulation path which detours and cools the cold water of the return side piping 16c of the cold water circulation path 14c, and the circulation path which cools the cooling water of a refrigerator are formed similarly to 2nd Embodiment.

Each operation switching when the cooling system of 3rd Embodiment changes in the external air wet bulb temperature range shown in FIG. 4 is shown below.
When the outside air wet bulb temperature is equal to or higher than T1, the cooling tower 70 functions as a refrigerator cooling tower. The cold water in the cold water circulation path has a flow shown in FIG. Accordingly, the cooling tower 70 supplies the refrigerator 20 with cooling water having a lower limit value of 7 degrees.

  When the outside air wet bulb temperature is T2 or more and T1 or less, the cooling tower 70 functions as a free cooling cooling tower and a refrigerator cooling tower. That is, the valves 74a and 74b are closed to supply the cooling water with the lower limit of 7 degrees for the refrigerator side for the refrigerator. On the other hand, on the free cooling side, cold water of T2 or more and T1 or less is supplied to the refrigerator 20c as a free cooling cooling tower using the outside air wet bulb temperature. The cold water in the cold water circulation path has the flow shown in FIG.

  When the outside air wet bulb temperature is T3 or more and T2 or less, the cooling tower 70 functions as a free cooling cooling tower and a refrigerator cooling tower. That is, the valves 73a and 73b are closed to supply the cooling water with the lower limit value of 7 degrees for the refrigerator side for the refrigerator. On the other hand, on the free cooling side, cold water of T3 or more and T2 or less is supplied to the refrigerator 20b as a free cooling cooling tower using the outside air wet bulb temperature. The cold water in the cold water circulation path has the flow shown in FIG.

  When the outside wet bulb temperature T3 or lower, the cooling tower 70 functions as a free cooling cooling tower. That is, as a free cooling cooling tower using the outside air wet bulb temperature, cold water of T3 or lower is supplied to the refrigerator 20a, and cooling water of T3 or lower is supplied to the refrigerator 20a. The cold water in the cold water circulation path has the flow shown in FIG.

  As described above, the cooling system according to the third embodiment integrates the cooling tower for the refrigerator and the free cooling cooling tower with the pipe, and uses the cooling tower 70 as much cooling water as necessary while manufacturing the cooling water. The lower limit of the cooling temperature is determined by the refrigerator. In order to fully demonstrate the capacity of the cooling tower for refrigerators in winter, cold water as low as possible (lower limit of 7 degrees) is produced. As the cooling water, it is necessary to keep the temperature above a certain level, so that the return temperature of the cooling water exiting the refrigerator is bypassed by the bypass pipe 51, and the opening / closing amount is controlled by the three-way valve 53, and the low temperature cold water The temperature is adjusted by mixing.

  FIG. 7 is a diagram showing a fourth embodiment of the cooling system according to the present embodiment. As shown in the figure, only a pipe 60b for sending the cold water of the return side pipe 16b of the cold water circulation path 14b to the forward side pipe 18c of the cold water circulation path 14c is provided. The cold water discharge side pipe 67 of the free cooling cooling tower 30 is not connected to the return side pipe 16a, but is connected to the return side pipes 16c and 16b. With such a configuration, the load cold water temperature can be set high, and the operation time of the free cooling cooling tower can be extended. In addition, you may apply to the structure which integrated the cooling tower shown in 3rd Embodiment.

  FIG. 8 is a view showing a fifth embodiment of the cooling system according to this embodiment. The fifth embodiment is a modification of the first embodiment. A different configuration from the first embodiment is that each chilled water circulation path is not provided with a bypass pipe 38 as shown. With such a configuration, when the cold water temperature of the return side pipe is lower than or equal to the cold water set temperature mainly during winter operation, the flow rate to be flown into the free cooling cooling tower 30 is adjusted by the valve 36 and is also flown into the refrigerator 20. The cold water temperature may be adjusted.

1 shows a schematic configuration of a cooling system using free cooling according to a first embodiment of the present invention. It is an operation | movement flowchart of the cooling system which concerns on this invention. It is a figure which shows 2nd Embodiment of this invention. It is a figure which shows the relationship between outside temperature and outside air humidity. It is explanatory drawing of the driving | operation switching of the cooling system based on external wet-bulb temperature. It is a figure which shows 3rd Embodiment of this invention. It is a figure which shows 4th Embodiment of this invention. It is a figure which shows 5th Embodiment of this invention. It is a figure which shows the structure outline of the conventional cooling system.

Explanation of symbols

1 ......... Cooling system, 2 ......... Refrigerator, 3 ......... Cooling tower for refrigerator, 4 ......... Free cooling cooling tower, 5 ......... Cooled water tank, 6 ......... Pump, 7 ......... Load, 10 ......... Cooling system, 12 ......... Load, 14 ......... Cooled water circulation path, 16 ......... Return side piping, 18 ......... Outward side piping, 20 ......... Refrigerator, 30 ......... Free cooling cooling tower, 32 ......... inlet pipe, 34 ......... discharge pipe, 36 ......... valve, 38 ......... bypass pipe, 39 ......... valve, 40 ......... cooling tower for refrigerator, 42 ... ... Cooling water circulation path, 44 ......... Return side piping, 46 ......... Outward side piping, 50 ......... Control means, 51 ......... Bypass pipe, 52 ......... Return side cold water temperature sensor, 56 ......... Outside wet bulb temperature sensor, 60 ......... Piping, 62 ......... Valve, 64 ...... Pump.

Claims (3)

A plurality of chilled water circulation paths that circulate the chilled water including a load and a chilled water refrigerator that flows to the load are formed for each of the loads having different chilled water set temperatures,
The first chilled water circulation path includes a free cooling cooling tower that cools the chilled water in the return side pipe and returns it to the return side pipe in the second chilled water circulation path that is lower than the chilled water set temperature of the first chilled water circulation path,
A pipe directly connecting the return side pipe of the second cold water circulation path and the forward side pipe of the first cold water circulation path;
The chilled water cooled by the free cooling cooling tower based on the outside air wet bulb temperature is returned to the return side piping of the second chilled water circulation path and cooled by the refrigerator, and the chilled water of the return side piping of the second chilled water circulation path is A cooling system using free cooling, characterized in that a control means for supplying to the outgoing piping of the first cold water circulation path is provided. Cooling system using free cooling according to claim 1, characterized in that the integration of the free cooling tower and the cooling tower of the refrigerator. Cooling the chilled water flowing through the return side piping of the first chilled water circulation path out of the chilled water circulation path of the refrigerator and the load divided into multiple for each load having different chilled water set temperature
The chiller cooled by the return side piping of the first cold water circulation path based on the outside air wet bulb temperature is returned to the return side piping of the second cold water circulation path lower than the cold water set temperature of the first cold water circulation path. Cool with
A cooling method using free cooling, wherein cold water in a return side pipe of the second cold water circulation path is supplied to a forward side pipe of the first cold water circulation path.

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