JP3127155B2 - Thermal storage system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heat storage system used for cooling and heating buildings and the like, and more particularly to a heat storage system for storing a heat medium cooled or heated by a heat source device in a heat storage tank.

[0002]

2. Description of the Related Art Conventionally, heat source equipment has been used at night to reduce the capacity and operating cost of heat source equipment by absorbing fluctuations in air conditioning loads of buildings and the like, and to save energy by operating heat source equipment with high efficiency. There is adopted a heat storage system in which cold water or hot water generated by operating a full load is stored in a heat storage tank and is used as a heat medium to be supplied to a secondary device such as an air conditioner. The heat storage operation includes a cooling heat storage operation for storing cold water and a heating heat storage operation for storing hot water. The cooling heat storage operation will be described below as a representative.

In this type of heat storage system, as shown in FIG. 4, high-temperature side cold water stored in a heat storage tank 51 is supplied to a heat source device 53 by a primary pump 52 and cooled to a predetermined temperature by the heat source device 53. The chilled water is returned to the low temperature side of the heat storage tank 51, and the low temperature chilled water is conveyed to a secondary device 57 such as an air conditioner by a secondary pump 56, and heat is exchanged by the secondary device 57. The cooled water is returned to the high temperature side of the heat storage tank 51. By the way, since the secondary equipment 57 such as an air conditioner is subjected to coil selection and the like based on the supply temperature of the cold water set at the design stage,
In the heat storage system as described above, it is important to store the cold water at the supply temperature to the secondary device 57.

For this reason, in the conventional heat storage system, the chilled water inlet temperature of the heat source device 53 detected by the temperature detector 55 is equal to the temperature of the chilled water supplied to the secondary device 57 (the chilled water outlet temperature of the heat source device 53). By mixing the low-temperature side cold water with the high-temperature side cold water stored in the heat storage tank 51 by the mixing three-way valve 54 so that the predetermined temperature calculated from the rated inlet / outlet temperature difference Δt of the heat source device 53 is obtained. , When the heat source device 53 is operated at full load
Constant flow rate to set the chilled water outlet temperature to a predetermined temperature (set temperature)
An inlet temperature control method is generally employed.

However, in such a heat storage system using the heat storage tank 51, the heat storage tank 5
The cold water on the high-temperature side 1 is also gradually cooled, and the cold water inlet temperature of the heat source device 53 falls below a predetermined temperature in the middle of heat storage. The heat source equipment 5 in such a state.
In order to maintain the chilled water outlet temperature at a predetermined temperature in Step 3, the heat source device 53 must be operated under partial load, and the heat source device 53 must always be operated with high efficiency from the start of heat storage to the completion of heat storage. There is a problem that can not be.

By the way, a heat pump chiller, which is a kind of heat source equipment, has been premised on use at a constant temperature difference and a constant flow rate. In recent years, however, a large temperature difference / variable flow rate heat pump capable of controlling an outlet temperature by a variable flow rate has been used. With the development of the chiller, as shown in FIG. 5, such a large temperature difference / variable flow rate type heat pump chiller is used as the heat source device 63 of the heat storage system, and the heat source device detected by the temperature detector 64 is used. When the flow rate of the chilled water supplied to the heat source device 63 is controlled by the inverter pump 62 or the like so that the chilled water outlet temperature of the heat source device 63 becomes the set temperature, the heat source device 63 is constantly turned on all the time from the start of the heat storage to the completion of the heat storage. It is possible to construct a high-efficiency heat storage system that can perform load operation.

[0007]

However, if it is attempted to construct a high-efficiency heat storage system using the above-mentioned variable flow rate type heat source device 63, the pump 62 to be installed naturally has the same structure as the heat source device 63. It is necessary to select a large capacity capable of flowing the allowable maximum flow rate, and there is a problem that the initial cost increases.

Further, the fact that a large flow of cold water must be supplied to the heat source device 63 is because the temperature of the high-temperature side cold water stored in the heat storage tank 61 has dropped and the heat source device 63 has to be fully loaded. Since the temperature difference between the inlet and the outlet of the heat source device 63 must be kept small for the operation, it is only one time immediately before the completion of heat storage, and if such a large capacity pump 62 is installed, most of the heat storage operation Since the pumping is performed in a state where the water supply capacity is suppressed, there is a problem that the operation efficiency of the pump 62 is poor and there is much waste.

It is an object of the present invention to realize a high-efficiency heat storage system by controlling a variable flow rate and outlet temperature without installing a pump having an unnecessarily large capacity.

[0010]

Means for Solving the Problems and Their Effects In order to solve the above problems, the present invention pumps a high-temperature side or low-temperature side heat medium stored in a heat storage tank by a pump and supplies the medium to a heat source device. In a heat storage system configured to return the heat medium cooled or heated by the heat source device to a low temperature side or a high temperature side of the heat storage tank, the heat medium pumped from the heat storage tank by the pump passes through a common flow path. Through which the heat source devices are distributed and supplied, respectively, and the individual flow path of the heat medium for each of the heat source devices is cut off when each of the heat source devices stops operating. So that the heat medium cooled or heated by the heat source device becomes a set temperature, while controlling the number of operating the plurality of heat source devices, There is provided a thermal storage system which is characterized in that so as to control the supply flow rate to the heat source device of the serial heating medium.

As described above, in this heat storage system, the heat medium pumped by the pump is distributed and supplied to the plurality of heat source devices through the common flow channel, and the individual flow passages for each heat source device are provided by the heat source devices. Since it is configured to be shut off when operation is stopped, when a large amount of heat medium must be supplied to the heat source equipment in order to reduce the temperature difference between the entrance and exit of the heat medium to the heat source equipment By reducing the number of operating heat source devices, the heat medium supplied to the stopped heat source devices is distributed to and supplied to the continuously operating heat source devices. It is not necessary to install a large-capacity pump capable of flowing the total flow rate of the maximum allowable flow rate, and the capacity to flow an intermediate flow rate within the flow rate variation range permitted by the heat source equipment By using a small pump,
It is possible to realize a more efficient heat storage system at low cost.

Also, as in the heat storage system according to claim 2, each of the individual flow paths for each of the heat source devices is set such that the heat medium cooled or heated by each of the heat source devices has a set temperature. By opening and closing the provided valve, in the one that individually controls the supply flow rate of the heat medium to each of the heat source devices,
Since the variation in the outlet temperature of the heat medium generated between the heat source devices can be eliminated, the heat medium returned to the heat storage tank can be more accurately maintained at the predetermined temperature.

[0013]

Embodiments will be described below with reference to the drawings. As shown in FIG. 1, the heat storage system 1 includes a heat storage tank 11 for storing heat source water, four cold / hot water pumps 12a, 12b, 12c, 12d and four heat pump chillers 13a, 13b, 13c, 13d. And four cold and hot water pumps 12a to 12
d is distributed and supplied to the four heat pump chillers 13a to 13d through the common outgoing pipe 14 and the individual outgoing pipes 15a, 15b, 15c, and 15d.
The heat source water cooled or heated by the four heat pump chillers 13a to 13d is supplied to the individual return pipes 16a and 16d.
b, 16c, 16d and the common return pipe 17
A heat storage circulation path that is returned to 1 is formed. As shown in the figure, the four cold / hot water pumps 12a to 12d have their respective suction sides on the inlet side header 18a connected to the heat storage tank 11 by one pipe 19, and
Each discharge side is connected in parallel to the outlet header 18b, and the common outgoing pipe 14 is connected to the outlet header 18b.

The heat storage tank 11 is a multi-tank connection type in which a number of tanks formed by using a double slab of a building foundation are connected in series by a communication pipe. The heat storage circulation path is configured so that the heat source water pumped up by the pumps 12a to 12d is cooled or heated by the heat pump chillers 13a to 13d, and then returned to the tank at the other end. Therefore, in the case of the cooling heat storage operation for storing cold water, one end of the heat storage tank 11 for pumping the heat source water by the cold / hot water pumps 12a to 12d has a high temperature side, and the other end of the heat storage tank 11 to which the cooled heat source water is returned has a low temperature side. In the case of the heating and heat storage operation for storing hot water, the reverse is true. In addition, the display of "high temperature side" and "low temperature side" in FIGS. 1 to 3 indicates the case of the cooling heat storage operation.

Each of the cold and hot water pumps 12a to 12d has a maximum water flow capacity of 600 l / min.
Inverters 20a, 20b, 20 attached to each
By changing the number of revolutions of the motor which is the driving source according to c and 20d, the flow rate of each of the cold / hot water pumps 12a to 12d is controlled.

The heat pump chillers 13a to 13d
Is an air heat source heat pump chiller of a large temperature difference / variable flow rate type. In the case of full load operation, by changing the flow rate of the heat source water to be supplied in the range of 200 to 2100 l / min, the difference Δt Can be changed in the range of 15 to 3 ° C.

The individual return pipes 16a to 16d include:
Temperature detectors 22a, 22b, 22c, 22d for detecting the heat source water outlet temperatures of the heat pump chillers 13a to 13d.
Is provided, among the heat source water outlet temperatures of the heat pump chillers 13a to 13d detected by the temperature detectors 22a to 22d, in the case of the cooling heat storage operation, the heat source water outlet temperature of the heat pump chiller having the lowest temperature, In the case of heating and heat storage operation, the heat source water outlet temperature of the heat pump chiller with the highest temperature is used as the representative temperature, and the representative temperature is the set (heat storage) temperature (5 ° C for cooling heat storage operation and 50 ° C for heating heat storage operation). Four cold and hot water pumps 12
Similarly, the amount of heat source water to be supplied to the heat pump chillers 13a to 13d is changed by inverter control of a to 12d.

The individual outgoing pipes 15a to 15d include:
Butterfly valve 2 that opens and closes in conjunction with ON / OFF operation of the compressor of each heat pump chiller 13a to 13d
1a, 21b, 21c, and 21d are provided, and when any one of the heat pump chillers 13a to 13d stops operating, the heat source water is not supplied to the heat pump chiller. In the case of the heat storage system 1, in the cooling heat storage operation, the heat pump chiller 13 is used.
When the heat source water outlet temperature (representative temperature) of a to 13d becomes 4.5 ° C. or lower, the operation of any one of the heat pump chillers is stopped. In the heating heat storage operation, the heat sources of the heat pump chillers 13a to 13d are set. When the water outlet temperature (representative temperature) becomes 50.5 ° C. or more, the operation of any one of the heat pump chillers is set to be stopped.

The operation of the heat storage system 1 configured as described above will be described below by taking a cooling heat storage operation as an example. First, four cold and hot water pumps 12a to 12d
And the four heat pump chillers 13a to 13d are activated,
The heat source water stored in the heat storage tank 11 is pumped up from the high temperature side and supplied to the four heat pump chillers 13a to 13d for cooling. In the initial stage of the operation, the temperature of the heat source water pumped up from the heat storage tank 11 is usually high, so that the outlet temperature (representative temperature) of the heat pump chillers 13a to 13d is set to the set temperature of 5 ° C. Since the difference Δt must be increased, and the amount of heat source water to be supplied to the heat pump chillers 13a to 13d must be suppressed, the four cold / hot water pumps 12a to 12d are controlled based on the above-described representative temperature. By being controlled by the inverter, the operation is performed with the water supply capacity suppressed.

Thus, the heat pump chiller 13
heat source water cooled to 5 ° C. by the heat storage tank 1
When the temperature of the heat source water stored on the high temperature side of the heat storage tank 11 gradually decreases as the heat storage gradually advances by returning to the low temperature side of the heat pump chillers 13 a to 1.
In order to keep the outlet temperature (representative temperature) of 3d at the set temperature of 5 ° C., the inlet / outlet temperature difference Δt between the heat pump chillers 13a to 13d must be gradually reduced, and the inverter controlled chilled / hot water pump is used. The amount of heat source water supplied by 12a to 12d gradually increases.

However, each installed cold / hot water pump 1
2a to 12d, as described above, the maximum water supply amount is 600
1 / min, the allowable maximum flow rate of the heat source water is 2100 l
For each of the heat pump chillers 13a to 13d, the heat source water supply rate can be increased only up to about 600 l / min. Therefore, when the temperature of the heat source water pumped from the high temperature side of the heat storage tank 11 further decreases while the four cold / hot water pumps 12a to 12d are operating at the maximum water supply amount, the heat source water of the heat pump chillers 13a to 13d is further reduced. Since the outlet temperature is lower than 5 ° C., the representative temperature controlling the inverters 20a to 20d is 4.5 ° C.
, The operation of any one of the heat pump chillers is stopped, and the four cold / hot water pumps 12a to 12d
By supplying heat source water to three heat pump chillers,
A cold / hot water pump 12 controlled by an inverter while increasing the supply amount of heat source water per heat pump chiller
The outlet temperature of the heat source water is maintained at 5 ° C. by suppressing the amount of water supply from a to 12d as a whole.

In this way, by sequentially controlling the four cold and hot water pumps 12a to 12d while sequentially stopping the operating heat pump chillers 13a to 13d, the outlet temperature of the heat pump chiller (representative temperature) is controlled.
Is maintained at 5 ° C., and when all four heat pump chillers 13a to 13d stop operating, the cooling heat storage operation is completed.

As described above, in this heat storage system 1,
The heat source water pumped by the cold / hot water pumps 12a to 12d is distributed and supplied to the four heat pump chillers 13a to 13d through the common outward pipe 14, and the individual outward pipes 15a to 15 for the respective heat pump chillers 13a to 13d.
d is shut off by the butterfly valves 21a to 21d when the operation of the heat pump chillers 13a to 13d is stopped, and the heat pump chillers 13a to 13d to reduce the temperature difference Δt between the inlet and outlet of the heat source water with respect to the heat pump chillers 13a to 13d. When a state in which a large amount of heat source water has to be supplied to 13d is reached, by reducing the number of operating heat pump chillers 13a to 13d, the heat source water supplied to the stopped heat pump chiller is Since it is distributed and supplied to the heat pump chiller that is operating continuously, there is no need to install a large-capacity pump that can flow the total flow rate of the allowable maximum flow rate of each heat source device as in the past. Is small enough to allow an intermediate flow rate within the flow rate range allowed by By using the pump, it is possible to realize a high efficiency heat storage systems at low cost.

Also, four cold and hot water pumps 12a to 12d
And the four heat pump chillers 13a to 13d are connected via the common outgoing pipe 14, so that the number of pipes is reduced, and the space for pipe shafts and the like through which the pipes pass can be reduced. The overall cost can be reduced.

Further, in this heat storage system 1, since the outlet temperature control of the heat pump chillers 13a to 13d is adopted, the heat pump chillers 13a to 13d due to aging change.
It is possible to absorb a decrease in capacity of 3d, a capacity change due to a change in outside air temperature, and the like, and it is possible to always keep the outlet temperature of the heat source water constant.

The heat storage system 1 employs a variable flow rate control for keeping the outlet temperature of the heat source water constant by changing the flow rate of the heat source water supplied to the heat pump chillers 13a to 13d. -Compared with the inlet temperature control, there is almost no time delay attributed to the length of the pipe, etc., and the responsiveness to the change in the inlet temperature is improved. Therefore, as described above, the set outlet temperature (5 ° C.) Real-time control under delicate temperature conditions such as an operation stop temperature (4.5 ° C.) becomes possible.

In the above-described embodiment, the amount of water supplied to the cold / hot water pumps 12a to 12d is controlled by the inverters 20a to 20d. For example, as shown in FIG. Attach valve 23,
As in the case of the inverter control, the individual return pipes 16a to 16
By adjusting the opening of the flow control valve 23 based on the temperature detection signals from the temperature detectors 22a to 22d attached to the heat pump chillers 13a to 13d, it is also possible to control the supply amount of the heat source water to the heat pump chillers 13a to 13d. is there.

In particular, when the flow rate is controlled by a flow control valve without using an inverter, as shown in FIG. 3, a butterfly valve that opens and closes in conjunction with the ON / OFF operation of the compressor of each of the heat pump chillers 13a to 13d. 21
a to 21d are used as flow control valves, and individual return pipes 16a are used.
Based on the temperature detection signals from the temperature detectors 22a to 22d attached to the heat pump chillers 13a to 13d, the supply amounts of the heat source water to the heat pump chillers 13a to 13d are individually controlled. Since the variation in the outlet temperature of the heat source water generated between the heat pump chillers 13a to 13d can be eliminated, the heat source water returned to the heat storage tank 11 can be more accurately maintained at the set temperature. In this case, the individual return pipes 16a to 16d are not used as the butterfly valves 21a to 21d as flow control valves.
It is also possible to individually control the supply amount of the heat source water to the heat pump chillers 13a to 13d by a flow control valve separately attached to 16d.

Although not shown in the figure, the heat pump chillers 13a to 13a to 13c are combined with an inverter and a flow control valve.
It is also possible to control the supply amount of the heat source water to 13d. Specifically, a flow control valve (including the case where the butterfly valves 21a to 21d as described above are used as the flow control valves) provided in the individual outgoing pipes 15a to 15d or the individual return pipes 16a to 16d, respectively. Each temperature detector 2
Each of the opening degrees is adjusted based on the temperature detection signals from 2a to 22d, and the cold / hot water pump 12 is controlled by the inverter so that any of the flow control valves is always fully opened.
When the flow rate of a to 12d is controlled, the operation efficiency of the cold / hot water pumps 12a to 12d is better than when the flow rate is controlled only by the flow rate control valve, and when the flow rate is controlled only by the inverter. This can eliminate variations in the outlet temperature of the heat source water generated at the outlet.

In each of the above embodiments, a heat pump chiller is used as a heat source device. However, the present invention is not limited to this. By changing the supply amount of the heat source water, the outlet temperature of the heat source water can be reduced. Various heat source devices can be used as long as they can be controlled.

In each of the above-described embodiments, four heat pump chillers 13a to 13d having the same capacity are used. However, the number of heat source devices to be installed may be plural, and the capacities of the heat source devices are different. It may be something.

Further, in each of the above-described embodiments, four cold / hot water pumps 12a to 12d are used, but the number of pumps to be installed is not limited to four, and the necessary water supply capacity is taken into consideration. It is sufficient to divide it into one or a plurality of units and install them as appropriate.

In each of the above embodiments, a plurality of heat source devices (heat pump chillers) are connected to the individual outgoing pipes 15a to 15a.
Although it is connected to the outlet header 18b via 5d and the common outgoing pipe 14, it is also possible to connect the individual outgoing pipes 15a to 15d to the outlet header 18b, respectively. In this case, the outlet header 18b functions as a common channel. However, as described above, the use of the common forward pipe 14 reduces the number of pipes and can reduce the cost.

Further, in each of the above-described embodiments, the multi-layered heat storage tank 11 is employed. However, the present invention is not limited to this. A type of heat storage tank can be employed.

In the above embodiment, the heat source water outlet temperature is 5 ° C. or 50 ° C., and the heat pump chillers 13a to 13a
Although the operation stop temperature of 13d is set to 4.5 ° C. or 50.5 ° C., the heat source water outlet temperature and the operation stop temperature of the heat source device may be appropriately set in consideration of design conditions and the like.

In the above-described embodiment, the heat pump chillers 13a to 13d with an allowable flow rate of the heat source water of 200 to 2100 l / min and the cold and hot water pumps 12a to 12d with a maximum water supply of 600 l / min are installed. It is needless to say that the heat source equipment and the pump to be installed are not limited thereto, and may be appropriately selected in consideration of the secondary load, the heat storage operation time, and the like.

In the above-described embodiment, water (heat source water) is used as a heat medium. However, various heat mediums can be used as long as the liquid (fluid) can be transported by a pump. In particular, in consideration of heat storage efficiency and the like, it is desirable to use a heat medium having a large heat capacity and excellent economic efficiency.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a heat storage system according to the present invention.

FIG. 2 is a schematic configuration diagram showing another embodiment of the heat storage system according to the present invention.

FIG. 3 is a schematic configuration diagram showing another embodiment of the heat storage system according to the present invention.

FIG. 4 is a schematic configuration diagram showing a conventional heat storage system.

FIG. 5 is a schematic configuration diagram showing another conventional heat storage system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Thermal storage system 11 Thermal storage tank 12a, 12b, 12c, 12d Cold / hot water pump 13a, 13b, 13c, 13d Heat pump chiller 14 Common outgoing pipe (common flow path) 15a, 15b, 15c, 15d Individual outgoing pipe (individual flow path) 18b Outlet header (common flow path) 20a, 20b, 20c, 20d Inverter 21a, 21b, 21c, 21d Butterfly valve 22a, 22b, 22c, 22d Temperature detector 23 Flow control valve

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-247521 (JP, A) JP-A-6-34168 (JP, A) JP-A-3-99140 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) F25B 13/00 F24F 5/00 F25C 1/00

Claims (2)

(57) [Claims] 1. A high-temperature side or low-temperature side heat medium stored in a heat storage tank is pumped by a pump and supplied to a heat source device, and the heat medium cooled or heated by the heat source device is cooled to a low temperature side of the heat storage tank. Or in a heat storage system that returns to a high temperature side, the heat medium pumped from the heat storage tank by the pump is distributed and supplied to a plurality of the heat source devices through a common flow path. The individual flow path of the heat medium for each of the heat source devices is configured to be cut off when each of the heat source devices stops operating, and the heat medium cooled or heated by the heat source device is The flow rate of the heat medium supplied to the heat source device is controlled while controlling the number of operating the plurality of heat source devices so as to reach the set temperature. The heat storage system to be considered. 2. A valve provided in each of the individual flow paths for each of the heat source devices is opened and closed so that the heat medium cooled or heated by each of the heat source devices has a set temperature. 2. The apparatus according to claim 1, wherein the supply flow rate of the heat medium to the equipment is individually controlled.
A heat storage system according to claim 1.