JP2015117918A - Heat accumulation system and heat accumulation system control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat accumulation system with high system efficiency and a heat accumulation system control method.SOLUTION: A heat accumulation system S includes: a temperature-humidity sensor 34 detecting a temperature and a humidity of outdoor air; a heat accumulation tank 22 storing cold water and accumulating heat; a refrigerating machine 21 transferring cold to the cold water flowing into the refrigerating machine 21 from the heat accumulation tank 22; a cold-water primary pump 23 pumping the cold water up from the heat accumulation tank 22 toward the refrigerating machine 21 and returning the cold water, to which the cold is transferred in the refrigerating machine 21, to the heat accumulation tank 22; and a controller 40 controlling the refrigerating machine 21 and the cold-water primary pump 23. The controller 40 changes at least one of a set temperature of the refrigerating machine 21 and a flow volume of the cold-water primary pump 23 so as to increase system efficiency depending on the temperature and humidity of the outdoor air detected by the temperature-humidity sensor 34.

Description

  The present invention relates to a heat storage system including a refrigerator and a control method thereof.

  There is known a heat storage system in which cold water cooled by a refrigerator is temporarily stored in a heat storage tank, and the cold water is circulated from the heat storage tank through a heat load. In the heat storage system, heat storage operation is performed using nighttime electric power with a low power charge, and then cold water (that is, cold heat) stored in the heat storage tank is supplied to the heat load. Such a heat storage system has an advantage of facilitating power leveling between nighttime when power demand is low and daytime when power demand is high, and is widely used for air conditioning in offices.

  For example, Patent Document 1 discloses a load prediction unit that predicts a future air conditioning load using an ANN (Artificial Neural Network) model, and a plurality of refrigerators that satisfy the air conditioning load predicted by the load prediction unit. A heat storage tank heat source system control device including a heat source control unit for controlling the number of units is described.

JP 2008-82642 A

  In the technique described in Patent Document 1, an operation plan of a refrigerator (the number of refrigerators to be operated during heat storage, etc.) is established by a heat source control unit based on predicted air conditioning load data. However, Patent Document 1 does not disclose a specific control method for the refrigerator based on the outside air condition or the like. For example, there is room for further improving the system efficiency by controlling each device in consideration of the outside air condition, rather than driving a single refrigerator with a constant processing load and performing a heat storage operation.

  Then, this invention makes it a subject to provide a thermal storage system with high system efficiency, and its control method.

In order to solve the above-mentioned problems, a heat storage system according to the present invention includes a set temperature of a refrigerator and a refrigerant pump so as to increase system efficiency in accordance with the temperature and humidity of the outside air detected by the outside air temperature and humidity detecting means. At least one of the flow rates is changed.
Details will be described in an embodiment for carrying out the invention.

  The present invention can provide a heat storage system with high system efficiency and a control method thereof.

It is a lineblock diagram of the heat storage system concerning a 1st embodiment of the present invention. It is a block diagram of a controller. It is a characteristic view which shows the relationship between the load factor of a refrigerator, and system COP. It is a flowchart which shows the process at the time of the thermal storage driving | operation by a controller. In the heat storage system concerning a 2nd embodiment of the present invention, it is a flow chart which shows processing at the time of heat storage operation by a controller. It is a block diagram of the thermal storage system which concerns on 3rd Embodiment of this invention. It is a block diagram of a controller. It is a flowchart which shows the process which a controller performs before the start of a thermal storage driving | operation. It is explanatory drawing which shows transition of the external air wet bulb temperature of the next day, the load factor of a refrigerator, and system COP (maximum value). It is a flowchart which shows the setting process of the driving schedule of heat storage driving | operation. In the heat storage system concerning a 4th embodiment of the present invention, it is a flow chart which shows the setting processing of the operation schedule of heat storage operation.

<< First Embodiment >>
FIG. 1 is a configuration diagram of a heat storage system according to the present embodiment. In addition, the broken line arrow shown in FIG. 1 represents the signal line. The heat storage system S is a system that stores cold water (refrigerant) cooled by the refrigerator 21 in the heat storage tank 22 and then circulates cold water from the heat storage tank 22 through the indoor unit 25 to air-condition the room (cooling). is there.
The heat storage system S includes a cooling water circulation system Sa that circulates cooling water for generating cold water via the refrigerator 21, a cold water circulation system Sb that circulates cooling water for air conditioning via the heat storage tank 22, and a plurality of sensors ( Temperature sensors 31, 32, etc.) and a controller 40.

(Cooling water circulation system)
The cooling water circulation system Sa includes a cooling tower 11 and a cooling water pump 12.
The cooling tower 11 is a facility for cooling the cooling water whose temperature has been increased by absorbing heat from the cold water flowing through the refrigerator 21, and has a blower 11a that takes in outside air and blows it. The cooling tower 11 is, for example, an open type cooling tower, and is configured to flow cooling water into a filler (not shown) carried therein.

In addition, the inflow port of the piping p1 shown in FIG. 1 is connected to the refrigerator 21, and the outflow port is connected to the upper part of the cooling tower 11. The inlet of the pipe p <b> 2 is connected to the lower part of the cooling tower 11, and the outlet is connected to the refrigerator 21. In the cooling tower 11, the cooling water is cooled by latent heat of evaporation when a part of the cooling water evaporates or heat exchange (radiation of heat from the cooling water to the outside air) accompanying direct contact between the cooling water and the outside air.
The cooling water pump 12 is a pump that pumps the cooling water radiated and cooled by the cooling tower 11 toward the refrigerator 21, and is installed in the pipe p2.

(Cold water circulation system)
The cold water circulation system Sb includes a refrigerator 21, a heat storage tank 22, a cold water primary pump 23, a cold water secondary pump 24, and an indoor unit 25. In the cold water circulation system Sb, the refrigerator 21, the pipes p3 and p4, and the cold water primary pump 23 are collectively referred to as “primary side”. On the other hand, the indoor unit 25, the pipes p5 and p6, and the cold water secondary pump 24 are collectively referred to as “secondary side”.

  The refrigerator 21 is a cold heat source for applying cold heat to cold water (refrigerant) flowing in via the pipe p4. As the refrigerator 21, for example, a turbo refrigerator using a known refrigeration cycle can be used. The set temperature of the refrigerator 21 (the temperature of the cold water flowing out of the refrigerator 21) is adjusted according to a command from the controller 40.

The heat storage tank 22 is, for example, a temperature stratified heat storage tank, and is equipment that stores and stores low-temperature cold water flowing from the refrigerator 21. In addition, since cold water has a density and it tends to settle down, so that it is low temperature, the cold water stored in the thermal storage tank 22 becomes low temperature as it goes below. That is, there is a temperature gradient in the vertical direction in the heat storage tank 22, relatively low temperature cold water from the refrigerator 21 is stored in the lower region, and relatively high temperature cold water from the indoor unit 25 is stored in the upper region.
Further, the inlet of the pipe p3 shown in FIG. 1 is connected to the refrigerator 21, and the outlet faces the lower region of the heat storage tank 22. The inlet of the pipe p <b> 4 faces the upper region of the heat storage tank 22, and the outlet is connected to the refrigerator 21.

The chilled water primary pump 23 (refrigerant pump) pumps chilled water from the heat storage tank 22 to the refrigerator 21 via the pipe p4 and returns the chilled water supplied with the cold heat from the refrigerator 21 to the heat storage tank 22 via the pipe p3. It is a pump. As shown in FIG. 1, the cold water primary pump 23 is installed in the piping p4.
An inverter (not shown) is installed in a motor (not shown) that drives the cold water primary pump 23. By driving the inverter in accordance with a command from the controller 40, the rotational speed of the motor (that is, the flow rate of cold water) is adjusted.

The cold water secondary pump 24 is a pump that pumps cold water from the heat storage tank 22 to the indoor unit 25 via the pipe p5 and returns the cold water heated by the indoor unit 25 to the heat storage tank 22 via the pipe p6. As shown in FIG. 1, the cold water secondary pump 24 is installed in the piping p5. A motor (not shown) of the cold water secondary pump 24 is controlled by the controller 40.
Moreover, the inflow port of the pipe p5 faces the lower region of the heat storage tank 22, and the outflow port is connected to the heat transfer tube r of the indoor heat exchanger 25a. The inlet of the pipe p6 is connected to the heat transfer pipe r of the indoor heat exchanger 25a, and the outlet faces the upper region of the heat storage tank 22.

The indoor unit 25 (FCU: Fan Coil Unit) is installed in the room of the facility K and cools indoor air by heat exchange with cold water flowing in through the pipe p5. The indoor unit 25 includes an indoor heat exchanger 25a and an indoor fan 25b.
The indoor heat exchanger 25a performs heat exchange between the low-temperature cold water flowing through the heat transfer tube r and the high-temperature air taken in by the indoor fan 25b. The indoor fan 25b is a fan that takes in indoor air and sends it to the indoor heat exchanger 25a.

  The blower 11a, the cooling water pump 12, the refrigerator 21, the cold water primary pump 23, the cold water secondary pump 24, and the indoor fan 25b of the cooling tower 11 shown in FIG.

(Sensors)
The temperature sensor 31 (first temperature detection means) is a sensor that detects the temperature of cold water from the refrigerator 21 toward the heat storage tank 22, and is installed in the pipe p3. The temperature sensor 32 (first temperature detection means) is a sensor that detects the temperature of cold water from the heat storage tank 22 toward the refrigerator 21, and is installed in the pipe p4.
The flow rate sensor 33 (flow rate detection means) is a sensor that detects the flow rate of cold water from the refrigerator 21 toward the heat storage tank 22 (circulated on the primary side), and is installed in the pipe p3.

The temperature / humidity sensor 34 (outside air temperature / humidity detection means) is a sensor that detects the temperature and relative humidity of the outside air, and is installed at a predetermined position outside the facility K. Instead of the temperature / humidity sensor 34, a temperature sensor and a humidity sensor may be used separately.
Each sensor outputs its detection value to the controller 40.

(controller)
The controller 40 (control device) is configured to include electronic circuits such as a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces, and executes various processes according to a set program. To do.
The controller 40 controls driving of the blower 11a, the cooling water pump 12, the refrigerator 21, the chilled water primary pump 23, the chilled water secondary pump 24, and the indoor fan 25b according to the detection values input from the respective sensors described above. .

In addition, the controller 40 executes a plurality of operation modes including a heat storage operation, a follow-up operation, and a heat radiation operation.
The above-described “heat storage operation” is an operation mode in which cold water is cooled by the refrigerator 21 and the cooled cold water is stored in the heat storage tank 22. The “follow-up operation” is an operation mode in which the cold water cooled by the refrigerator 21 is circulated through the heat storage tank 22 and the indoor unit 25. The “heat radiation operation” is an operation mode in which low-temperature cold water stored in the heat storage tank 22 is circulated through the indoor unit 25.

FIG. 2 is a configuration diagram of the controller. The controller 40 includes a storage unit 41 that stores various types of information, and an arithmetic processing unit 42 that executes arithmetic processing.
The storage unit 41 stores a load characteristic DB (Data Base) 41a. The load characteristic DB 41a stores, as a database, characteristic information (see FIG. 9) indicating the relationship between the outdoor wet bulb temperature described later, the load factor of the refrigerator 21, and the system COP (Coefficient Of Performance) corresponding thereto. Has been.

  The “load factor of the refrigerator 21” is the ratio (%) of the processing load of the refrigerator 21 to the rated load of the refrigerator 21. The system COP (system efficiency) is the ratio of the cooling capacity to the power consumption (power required for cooling) of the heat storage system S.

FIG. 3 is a characteristic diagram showing the relationship between the load factor of the refrigerator and the system COP.
As shown in FIG. 3, the load factor that gives the maximum value of the system COP varies depending on the outside air wet bulb temperature. For example, when the outdoor wet bulb temperature is 15 ° C. WB, the system COP becomes the maximum value Y1 when the load factor of the refrigerator 21 is about 58%. When the outdoor wet bulb temperature is 20 ° C. WB, the system COP reaches the maximum value Y2 when the load factor of the refrigerator 21 is about 67%.

Returning again to FIG. 2, the description will be continued. The arithmetic processing unit 42 includes a processing load calculation unit 42a, a target load calculation unit 42b, a comparison unit 42c, and a control signal generation unit 42d.
The processing load calculation unit 42a calculates the load (processing load) processed by the refrigerator 21 at the current time based on the detection values of the temperature sensors 31 and 32 and the detection value of the flow rate sensor 33. That is, the processing load calculation unit 42 a detects the flow rate Q [m ³ / sec] of cold water flowing through the pipe p 3 (see FIG. 1), the detection value T _A [K] of the temperature sensor 31, and the detection of the temperature sensor 32. using the value T _B, a, and calculates the following processing load q of the refrigerator 21 based on the (equation 1) [kW]. In (Formula 1), C [kJ / kg · K] is the specific heat of water, and ρ [kg / m ³ ] is the density of water. As the density ρ, for example, the density of water at the average temperature of the temperatures T _A and T _B can be used.

q = Q × (T _B −T _A ) × C × ρ (Equation 1)

The processing load calculation unit 42a outputs the calculated processing load q to the comparison unit 42c.
The target load calculation unit 42b calculates the target load of the refrigerator 21 based on the temperature / humidity input from the temperature / humidity sensor 34 and the information read from the load characteristic DB 41a. Here, the “target load” means the processing load of the refrigerator 21 when the system COP becomes maximum corresponding to the temperature and humidity of the outside air detected by the temperature and humidity sensor 34.

For example, as shown in FIG. 3, when the outside air wet bulb temperature is 15 ° C. WB (Wet Bulb), the system COP reaches the maximum value Y1 when the load factor of the refrigerator 21 is about 58%. Therefore, the target load of the refrigerator 21 at the outside air wet bulb temperature of 15 ° C. WB is 0.58 × (rated load).
The target load calculation unit 42b outputs the calculated target load to the comparison unit 42c.

  The comparison unit 42c compares the processing load of the refrigerator 21 input from the processing load calculation unit 42a with the target load of the refrigerator 21 input from the target load calculation unit 42b, and controls the comparison result. It outputs to the signal generation part 42d.

  The control signal generation unit 42d, according to the comparison result input from the comparison unit 42c, the rotational speed of a motor (not shown) included in the chilled water primary pump 23 (see FIG. 1), the set temperature of the refrigerator 21, To control. Although omitted in FIG. 2, the control signal generator 42d also controls driving of the blower 11a, the cooling water pump 12, the cold water secondary pump 24, and the indoor fan 25b.

<Operation of heat storage system>
Hereinafter, the heat storage operation will be mainly described among the heat storage operation, the follow-up operation, and the heat radiation operation described above. FIG. 4 is a flowchart showing a process during a heat storage operation by the controller.
The controller 40 performs heat storage operation using relatively inexpensive nighttime power. When the predetermined time comes, the controller 40 starts the heat storage operation (START). That is, the controller 40 drives the blower 11a and the cooling water pump 12 to circulate the cooling water through the pipes p1 and p2. Moreover, the controller 40 drives the refrigerator 21 and the cold water primary pump 23, and circulates cold water on the primary side via the pipes p3 and p4.

  When the cold water primary pump 23 is driven, low temperature (for example, 5 ° C.) cold water flowing out from the refrigerator 21 flows into the lower part of the heat storage tank 22 through the pipe p3. Moreover, the comparatively high temperature (for example, 12 degreeC) cold water stored by the upper part of the thermal storage tank 22 is pumped to the refrigerator 21 via the piping p4. In this way, the cold heat generated by the refrigerator 21 is stored in the heat storage tank 22. As the cooling by the refrigerator 21 proceeds, the proportion of cold water that has been well cooled out of the cold water stored in the heat storage tank 22 increases from below.

After starting the heat storage operation (START), in step S101 of FIG. 4, the controller 40 reads the temperature and humidity of the outside air detected by the temperature and humidity sensor 34 (outside temperature and humidity detection step).
In step S102, the controller 40 calculates the outside air wet bulb temperature based on the temperature and humidity read in step S101.

In step S103, the controller 40 reads the cold water temperature T _A detected by the temperature sensor 31, the cold water temperature T _B detected by the temperature sensor 32, and the cold water flow rate Q detected by the flow sensor 33. .
In step S104, the controller 40 substitutes the temperatures T _A and T _B and the flow rate Q of the cold water read in step S103 into (Equation 1) by the processing load calculation unit 42a (see FIG. 2), and The processing load is calculated.

  In step S105, the controller 40 calculates a target load for maximizing the system COP by the target load calculation unit 42b (see FIG. 2). That is, the controller 40 refers to the load characteristic DB 41a (see FIG. 2), and among the load characteristics corresponding to the outside air wet bulb temperature calculated in step S102, the processing load of the refrigerator 21 that maximizes the system COP (that is, Target load).

  In step S106, the controller 40 determines whether or not the processing load calculated in step S104 substantially matches the target load calculated in step S105 by the comparison unit 42c (see FIG. 2). For example, the controller 40 performs the determination process of step S106 depending on whether or not the processing load of the refrigerator 21 exists within a predetermined range including the target load.

When the processing load of the refrigerator 21 substantially matches the target load (S106 → Yes), the controller 40 returns to “START” (RETURN). In this case, after a predetermined time has elapsed since the determination process in step S106, the controller 40 starts the process from step S101 onward again.
On the other hand, when the processing load of the refrigerator 21 does not substantially match the target load (S106 → No), the processing of the controller 40 proceeds to step S107.
In step S107, the controller 40 determines whether or not the processing load of the refrigerator 21 calculated in step S104 is smaller than the target load by the comparison unit 42c (see FIG. 2). When the processing load of the refrigerator 21 is smaller than the target load (S107 → Yes), the processing of the controller 40 proceeds to step S108.

  In step S108, the controller 40 increases the flow rate of the chilled water primary pump 23 (see FIG. 1) by a predetermined flow rate by the control signal generator 42d (see FIG. 2) (operation control step). Since the flow rate of the cold water primary pump 23 is increased, the processing load of the refrigerator 21 during the heat storage operation is also increased. Thereby, the processing load of the refrigerator 21 can be brought close to the target load, and the system COP can be increased.

Note that the amount of increase in the flow rate of the cold water primary pump 23 is set in advance so that the processing load of the refrigerator 21 gradually approaches the target load. Further, it is preferable to use a chilled water primary pump 23 having a relatively large allowable flow rate so that the refrigerator 21 can be operated at a target load only by adjusting the flow rate of the chilled water primary pump 23.
After performing the process of step S108, the process of the controller 40 returns to step S101 (RETURN).

On the other hand, when the processing load of the refrigerator 21 is larger than the target load (S107 → No), the processing of the controller 40 proceeds to step S109.
In step S109, the controller 40 decreases the flow rate of the chilled water primary pump 23 by a predetermined flow rate by the control signal generation unit 42d (see FIG. 2) (operation control step). Thus, the processing load of the refrigerator 21 during the heat storage operation is also reduced by the amount by which the flow rate of the cold water primary pump 23 is reduced. Thereby, the processing load of the refrigerator 21 can be brought close to the target load, and the system COP can be increased.
After performing the process of step S109, the process of the controller 40 returns to step S101 (RETURN).

  In addition, the heat storage operation is started so that the heat storage operation can be finished in the time zone (for example, 23: 00 to 7:00 on the next day) when the nighttime electricity rate is applied while changing the flow rate of the cold water primary pump 23 in this way. It is preferable to set the time earlier. When the heat storage tank 22 is filled with low-temperature water, the controller 40 performs a follow-up operation and a heat radiation operation according to a predetermined operation schedule after completing the heat storage operation.

<Effect>
In the present embodiment, the flow rate of the chilled water primary pump 23 is changed so that the processing load of the refrigerator 21 approaches the target load that maximizes the system COP. Thus, by finely changing the processing load of the refrigerator 21 according to the outside air condition (outside air wet bulb temperature), the energy required for the heat storage operation can be reduced, and energy saving and cost reduction can be achieved.

  Further, the heat storage operation can be continuously performed in the vicinity of the point where the maximum value of the system COP is given in the load characteristics while adjusting the processing load of the refrigerator 21 by simple control of changing only the flow rate of the cold water primary pump 23. Therefore, an excessive burden is not imposed on the arithmetic processing of the controller 40.

  If the heat storage operation is performed with the processing load of the refrigerator 21 as a fixed value, the difference between the processing load (fixed value) of the refrigerator 21 and the above-described target load varies with changes in the temperature and humidity of the outside air. Likely to grow. If it does so, the energy consumed by the whole system will become large, and the efficiency of heat storage operation will fall.

  On the other hand, in the present embodiment, during the heat storage operation, the heat storage operation is performed with high efficiency in order to adjust the processing load of the refrigerator 21 so as to maximize the system COP in the load characteristics corresponding to the outside wet bulb temperature. Can do.

<< Second Embodiment >>
The second embodiment is different from the first embodiment in the contents of the processing executed by the controller 40, but the first embodiment is the first configuration regarding the configuration of the heat storage system S (see FIG. 1) and the configuration of the controller 40 (see FIG. 2). This is the same as the embodiment. Therefore, a different part from 1st Embodiment is demonstrated and description is abbreviate | omitted about the overlapping part.

FIG. 5 is a flowchart showing a process during a heat storage operation by the controller. Note that the processes in steps S101 to S109 in FIG. 5 are the same as those described in the first embodiment (see FIG. 4).
In step S107, the controller 40 determines whether or not the processing load of the refrigerator 21 calculated in step S104 is smaller than the target load calculated in step S105. When the processing load of the refrigerator 21 is smaller than the target load (S107 → Yes), the controller 40 increases the flow rate of the cold water primary pump 23 by a predetermined flow rate in step S108. Thus, the controller 40 preferentially changes the flow rate of the chilled water primary pump 23 over the set temperature of the refrigerator 21 when changing the processing load of the refrigerator 21.

  Next, in Step S110, the controller 40 determines whether or not the flow rate of the cold water flowing through the pipe p3 (see FIG. 1) has reached the upper limit value of the flow rate of the cold water primary pump 23. That is, the controller 40 determines whether or not the value input from the flow sensor 33 has reached the flow rate (upper limit value) when the cold water primary pump 23 is rated. The above upper limit value is set in advance and stored in the storage unit 41 (see FIG. 2).

  When the flow rate of the cold water flowing through the pipe p3 reaches the upper limit value of the flow rate of the cold water primary pump 23 (S110 → Yes), the process of the controller 40 proceeds to step S111. In step S111, the controller 40 reduces the set temperature of the refrigerator 21 by a predetermined width while maintaining the flow rate of the cold water primary pump 23 in the vicinity of the upper limit value. That is, the controller 40 increases the processing load of the refrigerator 21 by lowering the set temperature of the refrigerator 21. Thereby, the processing load of the refrigerator 21 can be brought close to the target load, and the system COP can be increased.

Note that the increase range of the set temperature is set in advance so that the processing load of the refrigerator 21 gradually approaches the target load. After performing the process of step S111, the process of the controller 40 returns to step S101 (RETURN).
When the flow rate of the cold water flowing through the pipe p3 in step S110 does not reach the upper limit value of the flow rate of the cold water primary pump 23 (S110 → No), the process of the controller 40 returns to step S101 (RETURN). In this case, the controller 40 does not change the set temperature of the refrigerator 21.

When the processing load of the refrigerator 21 is larger than the target load (S107 → No), the controller 40 decreases the flow rate of the cold water primary pump 23 by a predetermined flow rate in step S109.
In step S112, the controller 40 determines whether or not the flow rate of the cold water flowing through the pipe p3 has reached the lower limit value of the flow rate of the cold water primary pump 23. The lower limit value described above is set in advance and stored in the storage unit 41 (see FIG. 2).

  When the flow rate of the cold water flowing through the pipe p3 reaches the lower limit value of the flow rate of the cold water primary pump 23 (S112 → No), the process of the controller 40 proceeds to step S113. In step S113, the controller 40 increases the set temperature of the refrigerator 21 by a predetermined width while maintaining the flow rate of the cold water primary pump 23 in the vicinity of the lower limit value. That is, the controller 40 reduces the processing load on the refrigerator 21 by increasing the set temperature of the refrigerator 21. Thereby, the processing load of the refrigerator 21 can be brought close to the target load, and the system COP can be increased.

After performing the process of step S113, the process of the controller 40 returns to step S101 (RETURN).
When the flow rate of the cold water flowing through the pipe p3 in step S112 does not reach the lower limit value of the flow rate of the cold water primary pump 23 (S112 → No), the process of the controller 40 returns to step S101 (RETURN). In this case, the controller 40 does not change the set temperature of the refrigerator 21.

<Effect>
According to this embodiment, even if the target load that gives the maximum value of the system COP is not reached only by adjusting the flow rate of the chilled water primary pump 23, the processing of the refrigerator 21 is performed by changing the set temperature of the refrigerator 21. The load can be brought close to (substantially matched) the target load. Therefore, the heat storage operation can be performed continuously with the system COP being high, and energy saving and cost reduction can be achieved.
Further, even if a pump having a relatively small range of the upper limit value and the lower limit value of the flow rate is used as the cold water primary pump 23, the system COP can be increased by changing the set temperature of the refrigerator 21.

«Third embodiment»
3rd Embodiment acquires the weather information of the next day from the point which added the several temperature sensor 35 (refer FIG. 6) installed in the thermal storage tank 22 compared with 1st Embodiment, and the weather information server W. FIG. This is different from the configuration of the controller 40A (see FIG. 7). Other points are the same as in the first embodiment. Therefore, a different part from 1st Embodiment is demonstrated and description is abbreviate | omitted about the part which overlaps with 1st Embodiment.

<Configuration of heat storage system>
FIG. 6 is a configuration diagram of the heat storage system according to the present embodiment.
The weather information server W is, for example, a server that manages weather information acquired from the Japan Meteorological Agency, and is connected to the controller 40A via the network N. Note that the weather information described above includes the predicted temperature and humidity of the outside air on the next day.

  For example, three temperature sensors 35 (second temperature detection means) are installed in the heat storage tank 22. Each temperature sensor 35 is installed at different heights (upper, middle, and lower) in the vertical direction. As described above, the temperature of the cold water stored in the heat storage tank 22 becomes lower as it goes downward. Each of the temperature sensors 35 detects the temperature of the cold water in the upper region, the middle region, and the lower region, and outputs the detected value to the controller 40A.

<Configuration of controller>
FIG. 7 is a block diagram of the controller. As shown in FIG. 7, the arithmetic processing unit 43 of the controller 40A includes a weather information acquisition unit 43a, a necessary heat storage amount calculation unit 43b, a target load calculation unit 43c, a schedule setting unit 43d, a control signal generation unit 43e, It has.
The weather information acquisition unit 43a (weather information acquisition means) acquires weather information of a predetermined area including the facility K from the weather information server W every predetermined time (for example, every 6 hours). The weather information acquisition unit 43a outputs the acquired weather information (including the predicted temperature and humidity of the outside air) to the necessary heat storage amount calculation unit 43b and the target load calculation unit 43c.

  The necessary heat storage amount calculation unit 43b fully stores the heat storage tank 22 based on the cold water temperature input from the temperature sensor 35 installed in the heat storage tank 22 and the weather information input from the weather information acquisition unit 43a. To calculate the amount of heat stored (hereinafter referred to as the required amount of stored heat). The aforementioned “full storage” means a state where the heat storage tank 22 is filled with cold water cooled by the refrigerator 21.

  The target load calculation unit 43c calculates the outdoor air wet bulb temperature at each time of the next day based on the temperature and humidity prediction value input from the weather information acquisition unit 43a. Furthermore, the target load calculation unit 43c refers to the load characteristic DB 41a and calculates the target load of the refrigerator 21 corresponding to the outdoor air wet bulb temperature at each time. The target load calculation unit 43c associates each time of the next day with the target load described above, and outputs it to the schedule setting unit 43d.

The schedule setting unit 43d determines the next day's operation schedule based on the required heat storage amount input from the required heat storage amount calculation unit 43b, the target load input from the target load calculation unit 43c, and the information of the load characteristic DB 41a. Set. Details of the process executed by the schedule setting unit 43d will be described later.
The control signal generation unit 43e generates a control signal for controlling the refrigerator 21 and the chilled water primary pump 23 according to the operation schedule set by the schedule setting unit 43d. Details of the processing executed by the control signal generator 43e will be described later.

<Operation of heat storage system>
(1. Operation schedule setting)
FIG. 8 is a flowchart showing a process executed by the controller before the start of the heat storage operation.
In step S201, the controller 40A acquires the weather information for the next 24 hours from the weather information server W by the weather information acquisition unit 43a (see FIG. 2). As described above, the weather information includes the predicted temperature and humidity of the outside air. The acquisition time of weather information is, for example, 23:00.

  In step S202, the controller 40A divides a time zone in which the heat storage operation may be performed into a plurality of times, and calculates the outdoor air wet bulb temperature at each time. For example, the controller 40A divides the time zone from 0:00 am to 7:00 am every 10 minutes, and calculates the outdoor wet bulb temperature every 10 minutes using the weather information acquired in step S101.

In step S <b> 203, the controller 40 </ b> A reads the detection value of the temperature sensor 35 installed in the heat storage tank 22. That is, the controller 40 </ b> A reads the cold water temperature at the current time in the upper region, the middle region, and the lower region of the heat storage tank 22.
In step S204, the controller 40A calculates the necessary heat storage amount q1 for fully storing the heat storage tank 22 by the required heat storage amount calculation unit 43b (see FIG. 7). That is, the controller 40A calculates the necessary heat storage amount for full storage from the current temperature distribution in the heat storage tank 22 based on the cold water temperature read in step S203.

  In step S205, the controller 40A calculates the target load of the refrigerator 21 at each time of the next day by the target load calculation unit 43c (see FIG. 2). That is, the controller 40A refers to the load characteristic DB 41a and calculates the processing load (that is, the target load) of the refrigerator 21 that maximizes the system COP among the load characteristics corresponding to the outdoor wet bulb temperature calculated in step S202. To do.

  FIG. 9 is an explanatory diagram showing transitions of the outdoor wet bulb temperature, the refrigerator load factor, and the system COP (maximum value) on the next day. As shown in FIG. 9, the outdoor air wet bulb temperature changes at each time (for example, every 10 minutes) of the next day, and accordingly, the load factor of the refrigerator 21 that gives the maximum value of the system COP also changes. For example, the controller 40 divides the time zone from 0:00 AM to 7:00 AM every 10 minutes, and sets the load factor (corresponding to the target load) of the refrigerator 21 that gives the maximum value of the system COP at each time. Identify. Then, the controller 40 stores the load factor of the refrigerator 21 and the time in the storage unit 41 in association with each other.

  In step S206 of FIG. 8, the controller 40A sets the driving schedule for the next day by the schedule setting unit 43d (see FIG. 2). That is, the controller 40A sets the operation schedule for the heat storage operation based on the weather information acquired in step S201, the necessary heat storage amount calculated in step S204, and the target load calculated in step S205.

FIG. 10 is a flowchart showing the setting process of the operation schedule of the heat storage operation.
In step S2061, the controller 40A sets the value m = 1. Here, the value m is a natural number that is sequentially incremented each time the processes of steps S2061 to S2067 are repeated. Further, the controller 40A sets the necessary heat storage amount q1 calculated in step S204 of FIG. 8 as the provisional heat storage amount q _pro used in steps S2064 and S2067.

In Step S2062, the controller 40A reads the target load at the time (t _end −mΔt). That is, the controller 40A reads the target load that is back by mΔt from the end time t _end of the heat storage operation. This target load has already been calculated in the process of step S205 (see FIG. 8). Further, the end time t _end (for example, 7:00 am of the next day) and the predetermined time Δt (for example, 10 minutes) of the heat storage operation are set in advance.

In the present embodiment, the end time t _end (see FIG. 9) of the heat storage operation is fixed in this way, and the start time t _start (see FIG. 9) of the heat storage operation is adjusted. Therefore, heat release from the heat storage tank 22 to the outside air can be suppressed by delaying the end time of the heat storage operation to the maximum while performing heat storage operation using inexpensive nighttime power. Thereby, the energy cost required for air conditioning can be reduced.

In step S2063, the controller 40A calculates the heat storage amount Δq in the time period from time (t _end −mΔt) to time (t _end − (m−1) Δt). That is, the controller 40A calculates the heat storage amount Δq when the refrigerator 21 is operated for the predetermined time Δt with the target load read in step S2062.
In step S2064, the controller 40A calculates the remaining heat storage amount q _rem by subtracting the heat storage amount Δq calculated in step S2063 from the heat storage amount q _pro . In the first calculation, the necessary heat storage amount q1 is used as the heat storage amount q _pro (S2061), but the value of the heat storage amount q _pro is sequentially updated (decreases) in step S2067 described later.

In step S2065, the controller 40A determines whether or not the necessary heat storage amount q1 is satisfied. That is, the controller 40A determines whether or not the remaining heat storage amount q _rem calculated in step S2064 is equal to or less than zero.

When the necessary heat storage amount q1 is not satisfied (S2065 → No), the process of the controller 40A proceeds to step S2067.
In step S2067, the controller 40A substitutes the remaining heat storage amount q _rem calculated in step S2064 as the provisional heat storage amount q _pro . Next, in step S2068, the controller 40A increments the value m and returns to the process of step S2062.

On the other hand, when the necessary heat storage amount q1 is satisfied (S2065 → Yes), the process of the controller 40A proceeds to step S2066. The time (t _end −mΔt) at this time becomes the start time t _start (see FIG. 9) of the heat storage operation on the next day. For example, if the required heat storage amount q1 is satisfied in a state where the predetermined time Δt is 10 minutes and the value m is 24, the controller 40A takes 4 hours on the next day (for example, in the time zone from 3 am to 7 am). Perform heat storage operation.

In step S2066, the controller 40A sets the set temperature of the refrigerator 21 and the flow rate of the cold water primary pump 23 at each time. That is, the controller 40A sets the set temperature of the refrigerator 21 so as to operate the refrigerator 21 with the target load calculated in step S205 of FIG. 8 in the time zone from the start time t _start to the end time t _end of the heat storage operation. And the flow rate of the cold water primary pump 23 are set.
Although omitted in FIG. 10, in step S <b> 206 of FIG. 8, the controller 40 </ b> A also sets the operation schedule for the follow-up operation and the heat radiation operation after performing the heat storage operation.

(2. Execution of operation schedule)
Next, the operation of the heat storage system SA according to the operation schedule will be briefly described.
When the start time t _start (for example, 3:00 am) of the heat storage operation is reached, the controller 40A starts the heat storage operation by the control signal generator 43e (see FIG. 7). That is, the controller 40A drives the cooling tower 11 and the cooling water pump 12, and circulates the cooling water through the pipes p1 and p2.
Further, the controller 40A drives the refrigerator 21 and the cold water primary pump 23 based on the operation schedule set in step S206, and circulates cold water through the pipes p3 and p4.

The controller 40A calculates the actual processing load of the refrigerator 21 based on the detection values of the temperature sensors 31, 32 (see FIG. 6) and the flow rate sensor 33 while the heat storage operation is being performed. Further, the controller 40A calculates a target load of the refrigerator 21 based on the outdoor wet bulb temperature at the current time.
Then, the controller 40A changes (corrects) at least one of the flow rate of the cold water primary pump 23 and the set temperature of the refrigerator 21 in real time so that the actual processing load of the refrigerator 21 approaches the target load.

  Thereby, the refrigerator 21 can be operated near the target load that gives the maximum value of the system COP, and the energy cost can be reduced. As a procedure for changing the processing load of the refrigerator 21, the method described in the first embodiment (see FIG. 4) or the second embodiment (see FIG. 5) can be used.

  After performing the heat storage operation, the controller 40A sequentially performs the follow-up operation and the heat radiation operation according to the set operation schedule. Detailed description of the follow-up operation and the heat radiation operation is omitted.

<Effect>
According to the heat storage system SA according to the present embodiment, when setting the operation schedule during the heat storage operation, the controller 40A sets the target load so that the system COP of the refrigerator 21 is maximized based on the weather information of the next day ( S205: See FIG. Thereby, since the heat storage operation can be performed with the system COP being high, the energy cost required for the heat storage system SA can be reduced.

  Moreover, since the controller 40A sets the operation schedule of the heat storage operation so as to satisfy the required heat storage amount q1, the heat storage tank 22 can be filled with low-temperature cold water on the next day. Thus, by making the heat storage tank 22 fully stored and storing sufficient cold heat, it is possible to perform a heat radiation operation or the like with a margin on the next day.

<< Fourth Embodiment >>
The fourth embodiment is different from the third embodiment in that when the operation schedule for the next day is set, the end time t _end of the heat storage operation is variable, but other points (configuration of the heat storage system SA: FIG. 6 and FIG. 7) is the same as in the third embodiment. Therefore, a different part from 3rd Embodiment is demonstrated and description is abbreviate | omitted about the overlapping part.
As described in the third embodiment, the controller 40A performs the processing of steps S201 to S205 in FIG. 8 before starting the heat storage operation, and then sets the operation schedule in step S206.

FIG. 11 is a flowchart showing the setting process of the operation schedule of the heat storage operation.
In step S2061a, the controller 40A sets m = 1 and n = 1, sets the necessary heat storage amount q1 as the temporary heat storage amount q _pro , and sets the time t1 as the temporary end time t _end of the heat storage operation. m = 1 and q _pro = q1 are the same as step S2061 described in the third embodiment (see FIG. 10).
The value n is a natural number that is sequentially incremented in step S2074 described later. The time t1 is an end time (for example, 7:00 am) of a time zone in which nighttime power is applied.

Steps S2062 to S2066, S2067, and S2068 are the same as those described in the third embodiment (see FIG. 10).
When the necessary heat storage amount q1 is satisfied in step S2065 (S2065 → Yes), the process of the controller 40A proceeds to step S2071. In step S2071, the controller 40A determines whether or not the time (t _end −mΔt) is included in a time zone (for example, 23:00 to 7:00 of the next day) to which the nighttime electricity rate is applied. The time (t _end −mΔt) is a provisional start time of the heat storage operation.

When the time t _end is included in the time zone to which the nighttime electricity rate is applied (S2071 → Yes), the process of the controller 40A proceeds to step S2072.
The controller 40A in step S2072, the time (t _end -mΔt) ~t system COP at each time of the _end (Maximum: 3, see FIG. 9) calculates an average value COP _ave of (n). The controller 40A stores the calculated average value COP _ave (n) in the storage unit 41 (see FIG. 6) in association with the value of n.

In step S2073, the controller 40A sets the provisional end time t _end of the heat storage operation as the time (t1-nΔt).
In step S2074, the controller 40A increments the value n, and then returns to the process of step S2062. By this processing, the provisional end time t _{end of} the heat storage operation is shifted by time Δt (going back in time). In this way, the controller 40A calculates the average value COP _ave (n) of the system COP (maximum value) in each time zone for a plurality of time zones in which the necessary heat storage amount q1 is satisfied.

When the time (t _end −mΔt) is not included in the time zone to which the nighttime electricity rate is applied in step S2071 (S2071 → No), the process of the controller 40A proceeds to step S2072. In this case, time (t _end -mΔt) nighttime rates for at least part of the ~t _end is not applied. Therefore, the controller 40A proceeds to the process of step S2075 without shifting the provisional end time t _end of the heat storage operation any more.

In step S2075, the controller 40A identifies the value n = 1, 2,... That maximizes the average value COP _ave (n). That is, the controller 40A specifies a time zone in which the average value COP _ave (n) is maximum among the time zones corresponding to the values n = 1, 2 _,. Then, the controller 40A determines these time zones (t1-nΔt-mΔt) to (t1-nΔt) as time zones for the heat storage operation.

  In step S2076, the controller 40A sets the set temperature of the refrigerator 21 and the flow rate of the cold water primary pump 23 with respect to the time zone set in step S2075 (the shaded portion in FIG. 9). The controller 40A sets an operation schedule so that the processing load of the refrigerator 21 matches the target load obtained in step S205 of FIG. 8 for each time included in the time zone.

<Effect>
According to the present embodiment, the end time t _end of the heat storage operation is shifted by time Δt, and the time zone for performing the heat storage operation is set so that the average value COP _ave (n) of the system COP (maximum value) becomes the largest. Set. Thereby, the heat storage operation can be performed in the time zone with the lowest energy cost while satisfying the necessary heat storage amount q1. Therefore, according to the present embodiment, further energy saving and cost reduction can be achieved as compared with the third embodiment.

≪Modification≫
As mentioned above, although heat storage system S and SA which concern on this invention were demonstrated by each embodiment, this invention is not limited to these description, A various change can be performed.
For example, in the first embodiment, the case where only the flow rate of the cold water primary pump 23 is changed has been described, but the present invention is not limited to this. That is, instead of the flow rate of the cold water primary pump 23, only the set temperature of the refrigerator 21 may be changed.
Specifically, when the processing load of the refrigerator 21 is smaller than the target load in step S107 of FIG. 4 (S107 → Yes), the controller 40 decreases the set temperature of the refrigerator 21. On the other hand, when the processing load of the refrigerator 21 is larger than the target load (S107 → No), the controller 40 increases the set temperature of the refrigerator 21. The system efficiency of the heat storage system S can be increased also by such control.

Moreover, although each embodiment demonstrated the case where the load characteristic of the refrigerator 21 was previously stored in load characteristic DB41a (refer FIG. 2), it is not restricted to this. That is, the load factor that maximizes the system COP may be calculated using a heat source simulator based on the outside air wet bulb temperature.
Moreover, although each embodiment demonstrated the case where the processing load of the refrigerator 21 was matched with target load, it is not restricted to this. That is, the processing load of the refrigerator 21 may be close to the target load, and it is not always necessary to match these. Even in this case, the energy cost can be reduced by increasing the system COP.

Moreover, although each embodiment demonstrated the process at the time of a thermal storage driving | operation, it is applicable also to a follow-up driving | operation. That is, when performing the follow-up operation, at least one of the flow rate of the chilled water primary pump 23 and the set temperature of the refrigerator 21 may be changed so that the processing load of the refrigerator 21 approaches the target load.
Moreover, although each embodiment demonstrated the case where the refrigerant | coolant which circulates through the cold water circulation system Sb shown in FIG. 1 was water, it is not restricted to this. That is, a refrigerant other than water may be used as long as cold heat can be conveyed.

S, SA Thermal storage system 11 Cooling tower 12 Cooling water pump 21 Refrigerator 22 Thermal storage tank 23 Cold water primary pump (refrigerant pump)
24 Cold water secondary pump 25 Indoor unit 31, 32 Temperature sensor (first temperature detecting means)
33 Flow rate sensor (flow rate detection means)
34 Temperature / humidity sensor (outside temperature humidity detection means)
35 Temperature sensor (second temperature detection means)
40, 40A controller (control device)
41 storage unit 41a load characteristic DB
42 arithmetic processing unit 42a processing load calculation unit 42b target load calculation unit 42c comparison unit 42d control signal generation unit 43 arithmetic processing unit 43a weather information acquisition unit (weather information acquisition means)
43b Required heat storage amount calculation unit 43c Target load calculation unit 43d Schedule setting unit 43e Control signal generation unit N Network W Weather information server

Claims (6)

Outside air temperature and humidity detection means for detecting the temperature and humidity of the outside air,
A heat storage tank for storing and storing the refrigerant,
A refrigerator that gives cold to the refrigerant flowing from the heat storage tank;
A refrigerant pump that pumps the refrigerant from the heat storage tank toward the refrigerator, and returns the refrigerant given cold by the refrigerator to the heat storage tank;
A control device for controlling the refrigerator and the refrigerant pump,
The controller is
At least one of the set temperature of the refrigerator and the flow rate of the refrigerant pump is changed so as to increase the system efficiency according to the temperature and humidity of the outside air detected by the outside air temperature and humidity detection means. Heat storage system. First temperature detecting means for respectively detecting the temperature of the refrigerant from the heat storage tank toward the refrigerator and the temperature of the refrigerant returning from the refrigerator to the heat storage tank;
Flow rate detecting means for detecting the flow rate of the refrigerant pumped by the refrigerant pump,
The controller is
In correspondence with the temperature and humidity of the outside air detected by the outside air temperature and humidity detection means, while calculating a target load that is a processing load of the refrigerator when the system efficiency is maximum,
Based on the detected value of the first temperature detecting means and the detected value of the flow rate detecting means, a current processing load of the refrigerator is calculated,
The heat storage system according to claim 1, wherein at least one of a set temperature of the refrigerator and a flow rate of the refrigerant pump is changed so that a processing load of the refrigerator approaches the target load. . The controller is
When bringing the processing load of the refrigerator closer to the target load, the flow rate of the refrigerant pump is preferentially changed,
When the flow rate of the refrigerant pump reaches an upper limit value, the processing load of the refrigerator is brought close to the target load by lowering the set temperature of the refrigerator,
The heat storage system according to claim 2, wherein when the flow rate of the refrigerant pump reaches a lower limit, the processing load of the refrigerator is brought close to the target load by increasing the set temperature of the refrigerator. Weather information acquisition means for acquiring weather information including predicted temperature and humidity values of outside air from a weather information server;
Second temperature detecting means for detecting the temperature of the refrigerant stored in the heat storage tank,
The controller is
Based on the temperature detected by the second temperature detection means before the start of the heat storage operation, calculate the necessary heat storage amount to fill the heat storage tank with the refrigerant given cold by the refrigerator,
In response to the temperature and humidity predicted value acquired by the weather information acquisition means, calculate the target load of the refrigerator at each future time,
The operation schedule of the heat storage operation is set so that the processing load of the refrigerator matches the target load, and the necessary heat storage amount is satisfied. The heat storage system according to item. The controller is
In response to the temperature and humidity predicted value acquired by the weather information acquisition means, the maximum value of the system efficiency at each future time is calculated,
For a plurality of time zones in which the necessary heat storage amount is satisfied, specify a time zone in which the average of the maximum values is the largest,
The heat storage system according to claim 4, wherein an operation schedule is set so as to perform the heat storage operation in the time period. An outside air temperature / humidity detecting means for detecting the temperature / humidity of the outside air, a heat storage tank for storing and storing the refrigerant, a refrigerator for supplying cold to the refrigerant flowing from the heat storage tank, and from the heat storage tank toward the refrigerator A refrigerant pump that pumps the refrigerant and returns the refrigerant to which the cold is given by the refrigerator to the heat storage tank, and a control method of a heat storage system comprising:
An outside air temperature and humidity detecting step for detecting the outside air temperature and humidity by the outside air temperature and humidity detecting means;
An operation control step of changing at least one of the set temperature of the refrigerator and the flow rate of the refrigerant pump so as to increase the system efficiency in accordance with the temperature and humidity of the outside air detected in the outside air temperature and humidity detection step. And a method of controlling the heat storage system.

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