JP2901918B2 - Method of controlling ice melting operation of ice thermal storage system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the operation of an ice storage system for making ice at night and then freezing it during the day and using it as a cold heat source, and in particular, a method for completely thawing all ice. About.

[0002]

2. Description of the Related Art In recent years, there has been a tendency to increase the cooling load in summer due to the amenity orientation for spending the summer comfortably in an urban space and the intelligent and office automation of office buildings. The increase in the cooling load not only increases the capacity of the cooling and heat source equipment for air conditioning, but also increases the difference in power load between day and night.
The ice heat storage system can make ice using nighttime electricity, and can be used during the daytime as a cooling heat source for cooling, so the effects of downsizing cooling heat source equipment for air conditioning and leveling the power load. And can be expected. In addition, the ice heat storage system uses the latent heat of ice in addition to the sensible heat of water, so a large amount of cold energy can be stored in a compact heat storage tank.
Introduction to building air-conditioning cooling and heat source systems and district cooling and heating systems is being promoted.

In order to make effective use of nighttime power, it is necessary to completely thaw ice produced at nighttime during the day. If the ice made on the previous day remains until the next ice making starts, it means that the cold heat accumulated during the night before the day was not completely used, resulting in heat loss during ice making and heat in the ice storage tank. Loss of efficiency results in loss of efficiency. In particular, in an ice heat storage system in which the ice heat storage tank has a simple structure, an ice-on-coil type, if there is residual ice, the ice will grow large and it will be easier to block. The circulation of cold water is hindered, and the accumulated cold heat cannot be used effectively.

A prior art for completely thawing an ice heat storage system is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-158137. In this prior art, a system is constructed by connecting multiple chilled water heat exchangers in parallel with chilled water source equipment such as refrigerators and heat pumps to control the number of chilled water heat exchangers and chilled heat source equipment. To respond to changes in cooling load. In particular, in order to promote defrosting, the number of operating chilled water heat exchangers is increased.

Japanese Patent Application Laid-Open No. Hei 7-133944 discloses, as another prior art, a system in which a heat storage system and a non-heat storage system are connected in series by a cold water pipe.

In order to detect the amount of heat storage, a method of detecting the water level of an ice heat storage tank is generally used. In general, the amount of accumulated heat is detected between the time of ice making and the time of melting ice, that is, the amount of accumulated heat, that is, the amount of accumulated heat is equivalent to the water level.

[0007]

As a prior art for completely thawing ice in the daytime with an ice heat storage system, in the system disclosed in Japanese Patent Application Laid-Open No. 4-158137, it is necessary to increase or decrease the number of operating chilled water heat exchangers. Therefore, it cannot be applied when the chilled water heat exchanger is one line. It is also possible to increase or decrease the flow rate of chilled water circulating through a series of chilled water heat exchangers to promote de-icing by variable flow control. However, not only chilled water heat exchangers but also chilled water pumps and chilled water pipes support large volumes. Must be performed, resulting in a significant cost increase.

As shown in the prior art of JP-A-7-133944, when a heat storage system and a non-heat storage system are connected in series by a cold water pipe, the operation of the non-heat storage system is stopped to increase the load on the heat storage system. However, it is difficult to smoothly change the system to change the capacity of the cold heat source equipment or to improve the overall capacity. Further, in the prior art that detects the heat storage amount assuming that the water level of the ice heat storage tank shows the same change with respect to the heat storage amount at the time of ice making and at the time of ice melting, actually, there is a difference between the ice making time and the ice melting time. Since the water level of the ice heat storage tank corresponding to the amount of heat storage is different, it is not possible to accurately detect the remaining amount of heat storage at the time of melting ice.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for controlling the operation of an ice storage system in an ice heat storage system, which can completely defrost ice during the daytime with a simple configuration and can effectively use electric power at night. is there.

[0010]

SUMMARY OF THE INVENTION According to the present invention, in order to accumulate cold heat in an ice heat storage tank by ice making at night and to use the cold heat generated by melting ice during the day, the operation state of the ice melting and cold heat source equipment is controlled. In the method for controlling the deicing operation of an ice heat storage system performed according to a preset plan, the low-temperature water in the ice heat storage tank is circulated to the cold heat source side of the cold water heat exchanger, and separated from the cold heat source side of the cold water heat exchanger. The load side is connected in parallel with the load side of other chilled heat source equipment, and a constant flow of chilled water is circulated between the chilled water heat exchanger and the other chilled heat source equipment and the chilled heat load connected in parallel. The amount of decrease is monitored based on the water level in the ice storage tank, and when the amount of decrease is less than planned and other chilled heat source equipment is operating, the chilled water outlet temperature on the load side of the chilled water heat exchanger is monitored. Ice heat storage system characterized by control to reduce A thawing operation control method. According to the present invention, the load side of the chilled water heat exchanger separated from the chilled heat source side and the load side of another chilled heat source device are connected in parallel, and a constant flow of chilled water is circulated between the load side and the chilled heat load. Therefore, if the temperature of the chilled water outlet on the load side of the chilled water heat exchanger is reduced, the load on other chilled heat source devices relatively increases. Since a relatively large amount of cold heat supplied from the ice heat storage system to the cold load is supplied by increasing the decrease amount of the remaining heat storage amount, it is possible to promote thawing and reduce the remaining heat amount. Thawing can be promoted simply by improving the heat exchange capacity of the chilled water heat exchanger, and the deicing promotion operation is performed at a lower cost and simpler control compared to a configuration that controls the flow rate of chilled water. be able to.

Further, the present invention is characterized in that the control of the chilled water outlet temperature on the load side of the chilled water heat exchanger is performed by adjusting the flow rate of the low chilled water supplied to the chilled heat source side of the chilled water heat exchanger. In the present invention, the accumulation of cold heat by ice making is performed using an ice-on-coil type ice heat storage tank. According to the present invention, the low chilled water circulating between the ice-on-coil type ice heat storage tank and the cold heat source side of the chilled water heat exchanger is cooled by the chilled water circulating between the load side of the chilled water heat exchanger and the chilled heat load. Therefore, the disturbance to the water level of the ice heat storage tank is small, the remaining amount of ice in the ice heat storage tank can be accurately grasped from the water level, and an appropriate deicing operation can be performed.

Further, the present invention relates to a method for controlling the deicing operation of an ice heat storage system in which cold heat is accumulated in an ice heat storage tank by ice making at night and cold generated by defrosting during the day is utilized via a cold water heat exchanger. In the cold water heat exchanger, the cold heat source side and the load side are separated, and an ice heat storage system is configured to circulate the low cold water in the ice heat storage tank to the cold heat source side,
The water level change in the ice heat storage tank is measured in advance for ice making and ice melting, and the remaining heat storage amount in the ice heat storage tank is calculated from the water level at the end of ice making obtained according to the water level change during ice making. Defrosting operation control of an ice heat storage system characterized by detecting in accordance with the water level that changes linearly to the water level at the end of the defrosting operation, and performing defrosting so that the detected remaining amount of heat storage is eliminated Is the way. According to the present invention, ice produced at night is stored in the ice heat storage tank in a state where the ice coexists with water. Since ice is present in water in a state where it is attached to the periphery of the cooling pipe, the amount of ice increases and the water level rises. However, at the time of melting ice, the temperature of the water in the ice heat storage tank is not always uniform, so the water level corresponding to the heat storage amount during the ice melting operation is higher than the water level during the ice making operation corresponding to the same heat storage amount. Become. At the end of the thawing operation, the temperature of the water in the ice storage tank is high and some ice remains, and after a while, the ice is completely homogenized and the ice is completely melted to reach the reference water level. The change in water level between the ice making operation and the thaw operation is measured in advance, and the remaining amount of stored heat is detected in consideration of the difference in the water level, and the thaw operation is performed. Can be promoted. Since the low chilled water in the ice storage tank is circulated separately from the load side in the chilled water heat exchanger, the low chilled water does not flow directly to the load side, and the possibility of abnormal changes in the water level can be reduced. .

[0013] Further, the present invention circulates the low-temperature water accumulated in the ice heat storage tank to the cold heat source side of the cold water heat exchanger with the low temperature water between the ice heat storage tank and the cold water from the load side of the cold water heat exchanger. When taking out, the amount of deicing is controlled by the outlet temperature of the cold water. According to the present invention, the low chilled water circulating between the ice heat storage tank and the chilled water source side of the chilled water heat exchanger and the chilled water taken out from the load side of the chilled water heat exchanger are separated.
The water level of the ice heat storage tank is not affected by a leakage of a chilled water system supplied to the chilled heat load from the load side of the chilled water heat exchanger, for example, a leak from a shaft seal portion of the chilled water pump or a volume change due to a temperature change. , Can be accurately detected in accordance with the amount of remaining ice. When the outlet temperature of the chilled water on the load side of the chilled water heat exchanger is controlled to be low, a large amount of cold heat is transferred from the load side of the chilled water heat exchanger to the cold heat source side, thereby facilitating melting of ice in the ice heat storage tank.

According to the present invention, the load side of the chilled water heat exchanger and the load side of another chilled heat source device are connected in parallel, and the chilled water heat exchanger and other chilled heat source devices connected in parallel are connected to the chilled heat load. While circulating cold water at a constant flow rate, when performing the defrosting and the operation state of the cold heat source equipment according to a preset plan, monitor the reduction amount of the remaining heat storage, the reduction amount is less than planned, and When the other chilled water source device is operated, the chilled water heat exchanger is controlled so as to lower the chilled water outlet temperature on the load side. According to the present invention, the load side of the chilled water heat exchanger in which the ice heat storage tank is connected to the cold heat source side is connected in parallel with another cold heat source device, and the ice in the ice heat storage tank and the operation of the cold heat source device are operated. The intended purpose of the ice thermal storage system is achieved while performing the state according to a preset plan. While monitoring the amount of decrease in the remaining amount of heat storage, when the amount of decrease is smaller than planned and other chilled heat source equipment is operating, the temperature of the chilled water outlet on the load side of the chilled water heat exchanger is reduced, and the ice heat storage system is reduced. The amount of cold heat supplied from the chiller can be made larger than that of other cold heat source equipment, and the melting of ice in the ice heat storage tank can be promoted, and the load on other cold heat source equipment can be reduced.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the configuration of a heat source system for air conditioning to which a method for controlling an ice melting operation of an ice heat storage system according to an embodiment of the present invention is applied. As the cold heat source device operated in parallel with the ice heat storage system, No. 1 heat pump 1, no. 2 heat pump 2 and no. Three heat pumps 3 are provided. Cold heat from the ice heat storage system is extracted from the load side 4a of the chilled water heat exchanger 4. An ice-on-coil type ice heat storage tank 5 is connected to the cold heat source side 4 b of the cold water heat exchanger 4. In the ice heat storage tank 5, an ice making coil 6 is arranged, and freezes water 7 therearound to accumulate cold heat. Since ice is formed around the ice making coil 6, the water level 8 changes in accordance with the amount of ice. Cold heat source side 4 of cold water heat exchanger 4
The flow control valve 9 is connected to b.

From the load side 4a of the chilled water heat exchanger 4, the chilled water pipe 10, No. No. 1 heat pump 1, no. 2 heat pump 2 and no. 3 Heat pump 3 from cold and hot water pipe 1
1, 12, 13 are connected to a supply header tube 14 and a return header tube 15, respectively. An air conditioning load 16 and a bypass line 17 are connected in parallel between the supply header pipe 14 and the return header pipe 15. A bypass valve 18 is provided in the bypass line 17 and is controlled by a pressure controller 19 that detects the pressure of the supply header pipe 14. The cold water pipe 10 and the cold / hot water pipes 11, 12, 13 are provided with a cold water pump 20 and cold / hot water pumps 21, 22, 23.

In the air-conditioning heat source system shown in FIG. 1, water as a heat medium is supplied to the air-conditioning load 16 in a two-pipe system of a supply header pipe 14 and a return header pipe 15 as a cold / hot water system.
Cold water for cooling is supplied in summer and hot water for heating is switched in winter. The cold water for cooling is no. No. 1 heat pump 1, no. 2 heat pump 2 and no. 3 Heat is supplied from the heat pump 3 and the cold water heat exchanger 4. The temperature of the chilled water is, for example, 7 ° C., and the flow rate is an amount suitable for the load of the fan coil unit or the air handling unit of the air conditioner on the building side, which is the air conditioning load 16. The flow rate of the chilled water supplied to the air conditioning load 16 is adjusted by the bypass flow rate flowing from the supply header pipe 14 to the return header pipe 15 via the bypass line 17. The temperature of the return cold water from the air conditioning load 16 side is 10 to 12 ° C., and after joining with the bypass flow, each heat pump 1
３3 and the chilled water heat exchanger 4, and each is controlled at 7 ° C. by each heat pump and chilled water heat exchanger. Hot water for heating is supplied from each of the heat pumps 1 to 3 at about 45 ° C.

A control device 25 is provided for controlling each of the heat pumps 1 to 3 and the ice heat storage system. The control device 25 is provided with the target heat storage amount and the schedule of the ice melting operation from the load prediction control device 26. Control device 25
No. uses the nighttime electric power to supply ice of an amount corresponding to the given target heat storage amount. 1 heat pump 1 and no. 2 Operate the heat pump 2 to accumulate in the ice heat storage tank 5. The ice accumulated in the ice heat storage tank 5 is thawed according to the thaw operation schedule, and is taken out during the day on the following day. Since ice can be made with nighttime electricity and taken out as cold heat in the daytime, the cooling capacity of heat pumps 1 to 3 can be supplemented to meet the peak daytime cold load, and the cold heat source required for air conditioning can be provided. The downsizing of the device and the leveling of the power load can be achieved.

The remaining amount of heat stored in the ice heat storage tank 5 at the time of thawing is determined by the water level 8 of the ice heat storage tank 5. Water level 8 is water level detector 2
7 and input to the control device 25. The control device 25 lowers the control temperature of the temperature controller 24 when the remaining heat storage amount detected by the water level 8 of the ice heat storage tank 5 is larger than the remaining heat storage amount planned according to the schedule of the ice melting operation, Load side 4 of cold water heat exchanger 4
a) Reduce the cold water outlet temperature. In order to lower the chilled water outlet temperature on the load side 4 a of the chilled water heat exchanger 4, the low chilled water flowing from the low chilled water pipe 28 to the flow control valve 9 through the low chilled water pipe 28 for flowing the low chilled water to the cold source side 4 b of the chilled water heat exchanger 4. Control is performed to decrease the amount and increase the amount of low chilled water flowing to the cold heat source side 4b of the chilled water heat exchanger 4. In the present embodiment, the constant flow valves 29 to 32 are used to make the cold water pipeline 10 and the cold and hot water pipelines 11 to 12 have a constant flow rate.
Are installed respectively. By making the flow rates of the cold water pipe 10 and the cold / hot water pipes 11 to 12 constant, control related to a plurality of cold heat source devices can be simplified and easily performed. Since the flow rates of the cold water pipe 10 and the cold / hot water pipes 11 to 13 are made constant, the flow rate of the cold / hot water flowing through the supply header pipe 14 and the return header pipe 15 is also kept constant.
For circulating the low chilled water, a low chilled water pump 33 is provided.

In the present embodiment, the low chilled water flow rate on the chilled heat source side of the chilled water heat exchanger is controlled by the flow rate control valve 9.
It is also possible to control the low chilled water pump as an inverter motor driven pump.

No. 1 heat pump 1 and no. The heat pump 2 includes a brine line 36 for making ice in the ice heat storage tank 5 via brine lines 34 and 35, respectively.
Connected to. For example, during the time period from 22:00 to 8:00 on the following day, the brine is cooled using the nighttime electric power, and the water 7 in the ice heat storage tank 5 is frozen to accumulate cold heat. Brine
For example, a 40 to 50% aqueous solution of ethylene glycol is cooled to about -7 ° C. Brine pump 37,
By activating 38 and circulating brine through the ice heat storage tank 5, the water 7 is frozen to form ice on the outer surface of the ice making coil 6. The flow rate of the brine is kept constant by the constant flow valves 39 and 40. The number of operating heat pumps 1 and 2 is determined according to the target heat storage amount.

The ice heat storage tank 5 is of an ice-on-coil type having a simple structure. In the ice-on-coil type, the ice making coil 6
The ice on the outer surface of the car must not form a bridge with each other. Even if ice is made up to the rated latent heat storage capacity, the low chilled water needs to be able to flow around the ice, and if the flow of the low chilled water is interrupted, it becomes an obstacle to take out the accumulated cold heat. The formation of an ice bridge is likely to occur when ice making is started again in a state where the ice made on the previous day remains unmelted during the daytime. For this reason, once ice is made, it is important that the ice be completely thawed by the start of the next ice making.

FIG. 2 shows an operation state of the chilled water heat exchanger 4. In the normal operation shown in FIG. 2A, the temperature difference Δt1 between the load side 4a and the cold heat source side 4b is set to 5 ° C. At the time of the maximum heat radiation in FIG. 2B, the temperature difference is Δt2 = 3 ° C. = 0.6 × Δt1. Assuming that the flow rate of the cold water is constant at Fm ³ / h, the amount of heat exchanged during normal operation is as follows: Q1 = F × (12−7) = 5 × F Mcal / h The amount of heat exchanged at the time of maximum heat dissipation is: Q2 = F × (12-5) = 7 × F = 1.4 × Q1 Mc
al / h. Therefore, the heat transfer area A2 required for the maximum heat radiation to the chilled water heat exchanger 4 is 2.33 times as shown below as compared with the heat transfer area A1 required for normal operation.

A2 = A1 × Q2 / Q1 × △ t1 / △ t2 = 1.4 / 0.6 × A1 = 2.33 × A1 Actually, a chilled water heat exchanger 4 having a heat transfer area of A2 is used. During normal operation, the flow rate of the low-cooling water flowing to the cold heat source side 4b is reduced by the flow control valve 9 shown in FIG. If the amount of low chilled water flowing to the cold heat source side 4b is reduced by the flow control valve 9, the amount of heat exchanged decreases. If the flow rate control valve 9 increases the amount of low chilled water flowing to the chilled heat source side 4b, the heat of the load side 4a is deprived and the outlet temperature of the chilled water is lowered.

FIG. 3 shows the operation of the heat storage operation and the deicing operation by the control device 25 of FIG. With reference to FIGS. 1 and 3, when the target heat storage amount and the schedule of the deicing operation for the next day are input from the load prediction control device 26, the operation is started from step b1. For example, at the heat storage operation start time such as 22:00, the heat storage operation by ice making is started in step b2. From the target heat storage amount, it is determined whether the number of operating heat pumps 1 and 2 is one or two. When ice is formed and accumulated in the ice heat storage tank 5 by ice making, the water level 8 rises. The water level is detected in step b3, and if the target water level is not reached in step b4, the process returns to step b3. When the target water level is reached in step b4, the heat storage operation is stopped in step b5. In step b6, the process waits until the defrosting start time indicated in the defrosting operation schedule is reached.

When the defrosting start time in the daytime of the next day is reached,
In step b7, the chilled water pump 20 and the low chilled water pump 33
And start the defrosting operation. During the de-icing operation, the chilled water heat exchanger 4 is always given the first priority,
2, 3 are the second and subsequent priorities. The number of the cold heat source devices to be operated depends on the opening degree of the bypass valve 18 and the supply header pipe 1.
The control device 25 determines the load cooling heat amount calculated from the flow rate and the temperature difference of the cold water flowing through the return header pipe 4 and the return header pipe 15 so as to satisfy both of them.

When the ice in the ice heat storage tank 5 decreases as a result of the thawing operation, the water level 8 decreases. In step b8, it is determined whether or not the peak time period has elapsed. For example, from 13:00
If the peak time zone of the cooling load at 16:00 has elapsed, the water level is detected in step b9, and if it is higher than the planned water level, the set value S of the temperature controller 24 is determined in step b11.
V is reduced. The temperature controller 24 compares the detected value PV of the chilled water outlet temperature on the load side 4a of the chilled water heat exchanger 4 with the set value SV, and adjusts the opening of the flow control valve 9 with the output value MV so as to eliminate the deviation. I do. As a result, the cold water outlet temperature decreases. When the low chilled water discharge temperature rises in step b12, the ice-drying operation is ended in step b14.

When the temperature of the chilled water outlet from the load side 4a of the chilled water heat exchanger 4 decreases, the water temperatures of the supply header pipe 14 and the return header pipe 15 also decrease. When the heat pumps 1, 2, and 3, which are other cold heat sources, are also operating, the heat pumps 1, 2, and 3 have reduced cooling capacity, and the supply amount of the cold heat from the ice heat storage tank 5 is relatively small. Increase. The increase in the amount of cold heat supplied from the ice storage tank 5 promotes the thawing of the accumulated ice.

FIG. 4 shows the water level 8 in the ice heat storage tank 5 shown in FIG.
And the relationship between the amount of stored heat and the heat storage. Referring to FIG. 1 and FIG. 4, when there is no ice in the ice heat storage tank 5, the reference water level is set to 0. At the time of heat storage, the state in the ice heat storage tank 5 changes as indicated by →→. In the case of →, the temperature of the water 7 in the ice heat storage tank 5 is cooled from about 5 ° C. to 0 ° C., and cold heat is accumulated as sensible heat of the water 7. Water level 8 remains at the reference water level. →
In, the cold heat generated by ice making is accumulated as latent heat, and accordingly, the water level rises linearly to L3. In this embodiment, the latent heat storage capacity of the ice heat storage tank 5 is 500 USRT · h, and when the heat storage is performed up to this rated capacity, the water level 8 becomes about 85
mm. When the water level detector 27 detects that the water level L3 corresponding to the target heat storage amount Q3 has been reached, the control device 2
5 stops ice making by the heat pumps 1 and 2.

At the time of thawing, the state in the ice heat storage tank 5 changes as indicated by →. When cold water of 7 ° C. is supplied to the supply header tube 14, the temperature of taking out low-cooled water from the ice heat storage tank 5 is 5
It is judged that the de-icing operation is completed when the temperature reaches ℃. This is the state at this time, and ice of about 3% of the latent heat storage capacity still remains in the ice heat storage tank 5. The water level 8 does not return to the reference water level, but rises by a water level L4 of about 2.5 mm. This is due to the non-uniformity of the temperature in the ice heat storage tank 5. If time passes,
The ice melts due to the equalization of the temperature in the ice thermal storage tank 5 and the water level 8
Is the reference water level.

Although it has been confirmed that the change of the water level 8 from L3 to L4 at the time of deicing is substantially linear with respect to the heat storage amount, as described above, the water level L at the end of the deicing operation is determined.
4 does not match the reference water level. Water level L at the end of thaw operation
No. 4 hardly changes even when the heat storage amount is small as indicated by L3 ', and changes almost linearly to' →. In the present embodiment, the relationship between the water level and the amount of heat storage is actually measured in advance, and the remaining amount of heat storage at the time of melting ice is detected only by the water level. Since the cold water heat exchanger 4 is installed so that the low cold water in the ice heat storage tank 5 does not mix with the cold water flowing to the air conditioning load 16 side, the water level 8 in the ice heat storage tank 5 is affected by disturbance from the cold water system. I do not receive. In the chilled water system, leakage from the shaft seals of the chilled water pump 20 and the chilled / heated water pumps 21, 22, and 23 may occur, and the supply header pipe 14 and the return header pipe 15 may be used.
Changes in volume due to temperature change, and the ice heat storage tank 5
Is directly connected, a disturbance to the water level 8 may occur. In this embodiment, since the low-cooling water pump 33 is of a mechanical seal type, the water level 8 is hardly affected by disturbance.

After the peak period of the cooling load has elapsed, the water level planned based on the schedule of the de-icing operation is compared with the actually detected water level when the cooling load on the current day is lower than expected. This is for judging whether or not to promote the thawing. When it is determined that the decrease in the remaining heat storage amount is smaller than planned due to the decrease in the cooling load on the day, and one or more heat pumps 1, 2, and 3 in addition to the chilled water heat exchanger 4 are simultaneously operated. In addition, the deicing is promoted by lowering the cold water outlet temperature. The operating number of the chilled water heat exchanger 4 and the heat pumps 1, 2, 3 is not changed, and only the set value of the chilled water outlet temperature is automatically reduced.

The set temperature can be lowered by, for example, a method of lowering the temperature by a fixed amount such as 1 ° C.
There is a method of lowering the temperature so as to be 6 ° C. or more at 1 ° C. so as to be equal to or higher than the lower limit of the chilled water supply temperature from the entire operating cold source device. In the latter method, the temperature is calculated from the number of heat pumps 1, 2 and 3 operating at the same time and the amount of circulating chilled water, and the set temperature is reduced so as to be equal to or higher than the lower limit of the chilled water supply temperature. Chilled water heat exchanger 4 and heat pump 1,
When the amount of circulating chilled water is the same as that of the chilled water heat exchangers 2 and 3 and only one heat pump 1 is operated in addition to the chilled water heat exchanger 4, the set temperature of the chilled water heat exchanger 4 can be lowered to 5 ° C. it can. In this case, as shown in FIG. 2 (2), the heat transfer area A2 of the chilled water heat exchanger 4 is such that the set temperature shown in FIG.
It is only necessary to increase the heat transfer area A1 by about 2.3 times. The cold water heat exchanger 4 is a plate heat exchanger,
The cost increase for increasing the heat transfer area is small. By simply increasing the heat transfer area, the chilled water pump 20 and the chilled water pipe 10 do not need to be compatible with a large capacity, and cost can be reduced as compared with the conventional method. Heat pumps 1, 2, 3
If the control for simultaneously increasing the set temperature on the side is performed, the chilled water outlet temperature can be further reduced.

If the load is predicted even during the daytime, the cooling load planned for the previous day can be corrected, and the operation plan for the remaining time can be corrected with higher accuracy. The operation plan may include a concept of accelerating the thaw by changing the set temperature when it is determined that the thaw is not completed by the scheduled time.

FIG. 5 shows a configuration for controlling the chilled water outlet temperature on the load side 4a of the chilled water heat exchanger 4 according to another embodiment of the present invention. In the embodiment of FIG. 1, the low chilled water flowing to the cold heat source side 4b of the chilled water heat exchanger 4 is adjusted by the flow control valve 9 using a three-way valve.
The two two-way valves 41 and 42 are controlled by the temperature controller 44 to adjust the flow rate. When increasing the opening of one of the two-way valves 41 and 42, the opening of the other is reduced, and the flow rate of the low-temperature water flowing through both the two-way valves 41 and 42 is kept constant. Even with such a configuration, operation can be performed in the same manner as the embodiment of FIG.

[0036]

As described above, according to the present invention, a chilled water heat exchanger and a chilled heat source device are connected in parallel to a chilled heat load, and chilled water is defined between the chilled water heat exchanger and each chilled heat source device. Since the circulation is performed at the flow rate, if the temperature of the chilled water outlet of the chilled water heat exchanger is reduced, the thawing of the ice heat storage system is promoted, and the load on the chilled heat source device can be reduced. As an ice thermal storage system,
Although it is necessary to increase the capacity of the chilled water heat exchanger in advance, it is not necessary to control the flow rate of the chilled water, so the cost can be reduced compared to the configuration that controls the flow rate of the chilled water, and the control is simple. Can be done. The use of only one chilled water heat exchanger can promote the deicing operation.

Further, according to the present invention, since the ice heat storage tank is constituted by an ice-on-coil type, the structure of the ice heat storage tank can be simplified, and the ice can be reliably thawed. Ice control is also easy.

Further, according to the present invention, it is possible to easily detect the remaining amount of heat storage from a change in the water level in the ice heat storage tank, and to easily perform the thawing operation.

According to the present invention, the low-temperature water circulating between the ice heat storage tank and the cold heat source side of the cold water heat exchanger is separated from the cold water flowing to the load side of the cold water heat exchanger. The water level in the tank is not affected by leakage of the chilled water system supplied to the load side or disturbance due to volume change, and the amount of heat storage can be accurately detected.
Since the control of the defrosting operation can be performed based on the accurate remaining heat storage amount, the control of the defrosting operation can be performed easily and with high accuracy.

Further, according to the present invention, the remaining amount of heat storage is detected based on the water level of the ice heat storage tank, and when the amount of reduced ice is smaller than planned, the temperature of the chilled water outlet on the load side of the chilled water heat exchanger is lowered, Thawing can be promoted by relatively increasing the amount of cold heat supplied from the system to the amount of cold heat supplied from the cold heat source devices connected in parallel.

[Brief description of the drawings]

FIG. 1 is a piping diagram showing a configuration of an air conditioning heat source system to which an embodiment of the present invention is applied.

FIG. 2 is a schematic diagram showing the operation of the chilled water heat exchanger 4 of FIG.

FIG. 3 is a flowchart showing an operation of the control device 25 of FIG. 1;

FIG. 4 is a graph showing a relationship between a water level of the ice heat storage tank 5 of FIG. 1 and a heat storage amount.

FIG. 5 is a partial piping system diagram showing a configuration for controlling chilled water outlet temperature in another embodiment of the present invention.

[Explanation of symbols]

 1, 2, 3 heat pump 4 cold water heat exchanger 4a load side 4b cold heat source side 5 ice storage tank 6 ice making coil 7 water 8 water level 9 flow control valve 18 bypass valve 14 supply header pipe 15 return header pipe 16 air conditioning load 19 pressure controller Reference Signs List 20 cold water pump 21, 22, 23 cold / hot water pump 44 temperature controller 25 control device 26 load prediction control device 27 water level detector 41, 42 two-way valve

Continuation of front page (72) Inventor Masahiro Moriguchi 3-1-1, Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries, Ltd. Kobe Plant (56) References JP-A-8-35692 (JP, A) 62-162839 (JP, A) JP-A-9-33090 (JP, A) JP-A-63-183336 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) F24F 11 / 02 102 F24F 5/00 102

Claims (6)

(57) [Claims] 1. An ice storage device for accumulating cold heat in an ice heat storage tank by making ice at night and using the cold heat generated by melting ice during daytime to perform the operation of the ice melting and the operation of the cold heat source device according to a preset plan. In the method for controlling the de-icing operation of a heat storage system, the low-temperature water in the ice heat storage tank is circulated to the cold heat source side of the cold water heat exchanger, and the load side separated from the cold heat source side of the cold water heat exchanger and other cold heat source equipment. And a constant flow of cold water between the chilled heat load and the chilled water heat exchanger and other chilled heat source equipment connected in parallel. Monitoring based on the water level in the chilled water, and controlling to reduce the chilled water outlet temperature on the load side of the chilled water heat exchanger when the amount of reduction is less than planned and other chilled heat source equipment is operating. A method for controlling an ice melting operation of an ice heat storage system. 2. The cooling water outlet temperature on the load side of the chilled water heat exchanger is controlled by adjusting the flow rate of low chilled water supplied to the chilled heat source side of the chilled water heat exchanger. A method for controlling the defrosting operation of an ice heat storage system. 3. The method according to claim 1, wherein the accumulation of cold heat by ice making is performed using an ice-on-coil type ice heat storage tank.
Or the method for controlling the deicing operation of the ice storage system according to item 2. 4. A method for controlling the defrosting operation of an ice regenerative storage system in which cold heat is accumulated in an ice heat storage tank by ice making at night and cold generated by defrosting during the day is used via a cold water heat exchanger. In the exchanger, the cold heat source side and the load side are separated, and an ice heat storage system is configured to circulate the low cold water in the ice heat storage tank to the cold heat source side, and the water level in the ice heat storage tank is previously determined. The change is measured for ice making and ice melting, respectively, and the amount of heat stored in the ice storage tank is calculated from the water level at the end of ice making, which is determined according to the change in water level at ice making, to the water level at the end of ice melting operation. A method for controlling ice melting operation of an ice heat storage system, wherein the ice melting is performed in accordance with a water level that changes linearly, and the ice is melted so that the detected remaining amount of heat storage is eliminated. 5. A method for circulating low-temperature water stored in an ice heat storage tank with low-temperature water between an ice heat storage tank and a cold heat source side of a cold water heat exchanger, and extracting cold water from a load side of the cold water heat exchanger. To
5. The method of controlling the defrosting operation of an ice heat storage system according to claim 4, wherein the amount of defrosting is controlled by an outlet temperature of the cold water. 6. A load side of a chilled water heat exchanger and a load side of another chilled heat source device are connected in parallel, and between the chilled water heat exchanger and the other chilled heat source devices connected in parallel and the chilled heat load. When circulating chilled water at a constant flow rate and performing the operation of deicing and the operation of chilled heat source equipment in accordance with a preset plan, monitor the amount of decrease in the remaining amount of stored heat, 6. The method according to claim 5, wherein when the source device is operated, the temperature of the chilled water outlet on the load side of the chilled water heat exchanger is controlled to be reduced.