Freezing warehouse management system, defrosting determination processing device, and freezing warehouse management method

Abstract

This freezer warehouse management system adjusts the temperature in a freezer warehouse by controlling a cooling device that can switch between cooling and defrosting operations. This freezer warehouse management system comprises a current measurement unit, a storage unit, and a control unit. Furthermore, the current measurement unit measures the current value of a blower that blows air from the cooling device. The storage unit stores a reference current value which is the current value of the blower and serves as a reference for estimating the amount of frosting during the cooling operation. The control unit calculates the difference value between the current value measured by the current measurement unit and the reference current value, and performs control to switch from the cooling operation to the defrosting operation when the calculated difference value reaches a predetermined value. Furthermore, the control unit updates the reference current value stored in the storage unit on the basis of the current value measured by the current measurement unit during the cooling operation and the reference current value.

Description

Refrigerated warehouse management system, defrosting determination processing device, and refrigerated warehouse management method

[0001] The present invention relates to a refrigerated warehouse management system, a defrosting determination processing device, and a refrigerated warehouse management method.

[0002] In refrigerators used in refrigerated warehouses, frost gradually grows on the surface of the heat exchanger of the cooler during the process of cooling the air inside the warehouse. When frost grows on the surface of the heat exchanger, heat transfer between the refrigerant flowing inside the cooler and the surrounding air is hindered, which can result in a decrease in cooling performance. For this reason, defrosting operation is generally performed as needed to melt the frost on the heat exchanger surface.

[0003] Known methods for melting frost during defrosting operation include raising the temperature of the refrigerant flowing inside and using a heater or water spray as an external heat source. However, melting frost also heats the heat exchanger and the surrounding air, which becomes an unnecessary heat source for a refrigerated warehouse. Therefore, from the perspective of energy conservation, it is desirable to reduce the number of defrosting operations. Here, because it is difficult to accurately detect the amount of frost on the heat exchanger surface, it is common to start defrosting operation after a predetermined period of cooling operation, assuming that frost has formed. However, because the amount of frost varies depending on factors such as the humidity of the surrounding air, the amount of frost may not be constant even if the cooling operation time is the same.

[0004] If the amount of frost becomes excessive, not only does the efficiency of cooling operation decrease, reducing energy efficiency, but it can also cause reliability issues, such as making it easier for residual frost to form after defrosting operation. For this reason, it is generally necessary to limit the cooling operation time, and the increased frequency of defrosting operation is one of the factors that reduces energy efficiency.

[0005] To address this issue, for example, Patent Document 1 discloses a technique for determining whether an outdoor heat exchanger in an air conditioner has frosted by comparing the drive current of the outdoor fan with a preset reference current, which is said to enable accurate determination of whether the outdoor heat exchanger has frosted. This conventional technique also discloses that the drive current supplied to the outdoor fan when a predetermined time has elapsed since the start of heating operation or the end of defrosting operation may be stored as the reference current.

[0006] Furthermore, Patent Document 2 discloses a vehicle air conditioning system that includes a current value detection means for detecting the current value of a blower that is driven during heating operation, a current value determination means for determining whether the difference between the current value of the blower before frost formation and the detected current value exceeds a predetermined value, and a control means for switching from heating operation to defrosting operation when it is determined that the predetermined value has been exceeded.The patent document 2 discloses an example in which the current value of the outdoor fan at the start of heating operation when no frost has formed on the outdoor heat exchanger is used as the current value before frost formation.

[0007] JP-A-11-287538 JP-A 10-338025

[0008] As described above, in order to appropriately switch between cooling operation and defrosting operation, a current reference value, which is a fan current value under predetermined conditions, such as a current value before defrosting operation, may be used. Here, the inventors have found that various factors, such as the ambient environment in the warehouse and residual frost on the cooler, affect the reliability of the current reference value. This viewpoint is neither disclosed nor suggested in Patent Document 1 nor Patent Document 2, and is not recognized as a problem.

[0009] For example, changes in environmental conditions, such as frost formation on walls or the amount and arrangement of stored goods, can change the air flow within the warehouse and cause fluctuations in the current reference value. Furthermore, when the amount of frost is greater than expected, the frost may not completely melt during defrosting operation and remain as residual frost. Setting the fan current value for when residual frost is present as the reference value without taking into account such environmental conditions or the presence of residual frost can result in an incorrect estimation of the amount of frost, potentially resulting in a greater amount of frost than expected. An unexpected increase in frost amount is undesirable because it reduces cooling performance. Therefore, there is a need for a refrigerated warehouse management system equipped with a reliable frost amount estimation technology that can prevent excessive increases in the amount of frost by taking into account various factors, such as changes in the ambient environment within the warehouse and residual frost in the cooler. The aforementioned patent documents 1 and 2 do not take into account the impact that various factors, such as the ambient environment within the warehouse and residual frost in the cooler, can have on the reliability of the current reference value.

[0010] According to a first aspect of the present invention, there is provided a refrigerated warehouse management system as follows. That is, the refrigerated warehouse management system controls a cooling device that is capable of switching between cooling operation and defrosting operation. The refrigerated warehouse management system includes a current measurement unit, a memory unit, and a control unit. The current measurement unit measures the current value of a blower that blows air for the cooling device. The memory unit stores a reference current value, which is the current value of the blower and serves as a reference for estimating the amount of frost formation during cooling operation. The control unit calculates the difference between the current value measured by the current measurement unit and the reference current value, and performs control to switch from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value. The control unit updates the reference current value stored in the memory unit based on the current value measured by the current measurement unit during cooling operation and the reference current value.

[0011] According to a second aspect of the present invention, there is provided a defrost determination processing device as follows. That is, the defrost determination processing device controls a cooling device that is capable of switching between cooling operation and defrosting operation and that adjusts the temperature in a freezer warehouse. A memory unit stores a reference current value, which is a current value of a blower that blows air for the cooling device and serves as a reference for estimating the amount of frost formation during cooling operation. A processor calculates a difference between the current value of the blower and the reference current value, and performs control to switch from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value. The processor updates the reference current value stored in the memory unit based on the current value of the blower during cooling operation and the reference current value.

[0012] According to a third aspect of the present invention, there is provided a refrigerated warehouse management method as follows. That is, the refrigerated warehouse management method is a method for adjusting the temperature inside a refrigerated warehouse by controlling a cooling device that is switchable between cooling operation and defrosting operation. The refrigerated warehouse management method includes the steps of acquiring a current value of a blower that blows air for the cooling device, calculating a difference between the acquired current value and a reference current value that is a current value of the blower and serves as a reference for estimating the amount of frost formation during cooling operation, and switching from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value, and updating the reference current value based on the current value acquired during cooling operation and the reference current value.

[0013] According to the present invention, the amount of frost can be accurately estimated even when there are changes in the frost condition on surrounding structures, the amount of stored goods, etc., so that an energy-saving and highly reliable refrigerated warehouse management system can be constructed. Also provided are a defrost determination processing device and a refrigerated warehouse management method having similar effects.

[0014] FIG. 1 is a diagram illustrating an example of a system configuration according to the first embodiment. FIG. 2 is a diagram illustrating an example of a side view of a freezer compartment in which a cooler is arranged according to the first embodiment. FIG. 3 is a diagram for explaining an operation according to the conventional technology. FIG. 4 is an example of a control flowchart of a refrigeration device according to the first embodiment. FIG. 5 is a diagram for explaining an example of an operation of the refrigeration device according to the first embodiment. FIG. 6 is an example of a control flowchart of a refrigeration device according to a second embodiment. FIG. 7 is a diagram for explaining an example of an operation of the refrigeration device according to the second embodiment. FIG. 8 is an example of a control flowchart of a refrigeration device according to a third embodiment. FIG. 9 is a diagram for explaining an example of an operation of the refrigeration device according to the third embodiment.

[0015] First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG.

[0016] FIG. 1 is a diagram showing an example of a system configuration according to an embodiment of the present invention. In this embodiment, a freezer warehouse for storing items includes four freezer compartments (50a, 50b, 50c, and 50d), and each freezer compartment is cooled using a refrigeration unit 1. While the following description will be representatively given of the refrigeration unit 1, the system may also be implemented as a refrigeration unit, and the freezer warehouse or refrigerator may also be implemented. In addition, items such as, but not limited to, food, alcoholic beverages, medicines, and vaccines are stored or preserved in the freezer warehouse or refrigerated warehouse while maintaining a predetermined temperature.

[0017] The refrigeration device 1 has a refrigeration cycle consisting of a heat source unit 9 equipped with a compressor, etc., and coolers (10a to 10d shown) equipped in freezing chambers 50a to 50d connected by refrigerant piping 8, and each cooler (10a to 10d) operates based on instructions from an operation control processing unit 15 so that the temperature inside each freezing chamber (50a to 50d) becomes a predetermined temperature.

[0018] Each cooling machine (10a to 10d) is equipped with a current sensor (20a to 20d shown) that detects the value of the current flowing through the built-in fan, and the refrigeration device 1 uses the measurement value of this current sensor to determine whether or not defrosting operation is necessary in the defrosting determination processing unit 21, and if it determines that defrosting operation is necessary, it sends a signal to the operation control processing unit 15 to perform defrosting operation.

[0019] Here, the operation control processing unit 15 and the defrost determination processing unit 21, which are equipped with a processor and determine whether or not switching between the defrosting operation and the cooling operation is necessary and perform the actual control, may be collectively referred to as the control unit. In this example, the operation control processing unit 15 and the defrost determination processing unit 21 are described separately, but they may be included in the same configuration. In other words, they may be a single configuration having the functions of these configurations.

[0020] The refrigeration system 1 also has a storage unit (not shown). The storage unit stores a reference current value indicating the current value when the fan is operated under predetermined conditions, which is used by the defrost determination processing unit 21 when determining whether or not a defrosting operation is required. Here, the predetermined condition may be, for example, a state in the freezer warehouse at a certain point in time immediately after the end of a defrosting operation and where there is no residual frost. The reference current value is the current value flowing through the fan that is being driven. Note that the storage unit may be provided in the defrost determination processing unit 21, as an example. The storage unit may be configured as appropriate using a memory or the like.

[0021] In the refrigeration system 1, the fan 12 rotates at a constant speed, which makes it easier for the current sensor 20 to detect the current value. Therefore, if an inverter is provided, it is preferable to detect the current value while the fan 12 rotates at a constant speed. Alternatively, a correction formula relating the rotation speed and current value of the fan 12 may be prepared in advance, and the detected current value may be appropriately corrected using the correction formula. Note that this correction formula may be stored in a storage unit, for example.

[0022] 1 , the refrigeration device 1 may be configured to be able to communicate with a work management server 201 and a power management server 202 via a network. First, the refrigeration device 1 will be described in detail as an example of a refrigerated warehouse management system. Then, an example of a refrigerated warehouse management system further configured using the work management server 201 and the power management server 202 will be described.

[0023] 2 is a side view of an example of a freezing chamber 50 in which a cooler 10 is installed. Inside the freezing chamber 50, various distribution items 40, which are carried in by an operator through an entrance / exit 51, are stored on shelves 52 installed inside. In this example, the cooler 10 is placed on a mounting plate 55 located above the entrance / exit 51, and includes a fan 12, which is an example of an air blower, that blows air inside the freezing chamber 50 to a cooling heat exchanger 13 cooled by a refrigerant. The cooler 10 uses the fan 12 to blow the air inside the freezing chamber 50 through the cooling heat exchanger 13 cooled by a refrigerant, thereby maintaining the temperatures of the air inside the freezing chamber 50 and the distribution items 40 stored therein within a predetermined temperature range.

[0024] The air in freezer compartment 50 is always kept at a negative temperature (for example, the air in freezer compartment 50 is managed to be kept at -20°C, as an example). Therefore, moisture in the air that flows into freezer compartment 50 from the outside when goods 40 are carried in or out easily turns into frost, which adheres and grows not only on the surface of cooling heat exchanger 13 but also on various other surfaces, such as surface 30e of cooler 10, ceiling surface 30c and wall surface 30d inside freezer compartment 50, surface 30b of mounting plate 55, and surface 30a of shelf 52. In FIG. 2, examples of frost 30 that has adhered and grown are shown in grayscale (30a to 30e).

[0025] When frost accumulates and grows in this manner, the differential pressure required for fan 12 to circulate air within freezer compartment 50 increases. This changes the amount of airflow that fan 12 can deliver and the torque and current required to rotate motor 11 that drives fan 12. Note that this embodiment assumes that a propeller fan is used as fan 12, and in the case of a propeller fan, the value of the current flowing through fan 12 generally increases as the required differential pressure increases.

[0026] Therefore, the refrigeration system 1 utilizes this characteristic to estimate the amount of frost and control the defrosting operation using the current value detected by the current sensor 20. Specifically, the amount of frost is estimated according to the amount of change in the current value. Note that when a fan with different characteristics is used (for example, when a multi-blade fan is used), the fan current may decrease as the required differential pressure increases, but the present invention is applicable in either case. Furthermore, the number of freezing compartments 50 and coolers 10 is not limited to the number shown in the embodiment.

[0027] Before describing the detailed processing of this embodiment, the problems with the conventional technology will be explained again using FIG. 3 . FIG. 3 relates to the conventional technology, and the horizontal axis of the graph represents time. FIG. 3 shows the behavior of three operations, from the (n-2)th operation to the nth operation, when the period from the end of defrosting to the start of cooling operation until the next defrosting operation is counted as one operation. Here, the three upper and lower graphs show, from top to bottom, the actual amount of frost formed on the surface of the cooling heat exchanger, the fan current, and the estimated amount of frost over time. The example in FIG. 3 shows the behavior when the fan current at the start of cooling operation is used as the reference value, and in the (n-2)th operation, the fan current value ia at the start of cooling operation is set as the reference value base.

[0028] As the cooling operation continues, the amount of frost on the surface of the cooling heat exchanger increases, which increases the load on the fan for blowing air and also increases the fan current. At this time, the difference value x of the fan current value from the reference value base is correlated with the amount of increase in the fan load, i.e., the amount of frost, so the difference value x is used to calculate the estimated amount of frost. Therefore, when the difference value x reaches a predetermined threshold value d, it is determined that the estimated amount of frost has reached a predetermined limit frost amount mf, and a defrosting operation is started based on this determination. By using the difference value x in this way, it is possible to estimate the amount of frost and control the timing to start the defrosting operation according to the amount of frost.

[0029] Here, let us consider a case where residual frost occurs in such conventional technology. In the example of Fig. 3, it is assumed that the frost has been removed by the defrosting operation (i.e., there is no residual frost) at the start of the (n-1)th cooling operation, and the fan current ib at the start of the cooling operation drops to the reference value base, so operation is performed based on this reference value base. In this case, the amount of frost (actual amount of frost) and the estimated amount of frost coincide.

[0030] However, if residual frost occurs during defrosting operation after the (n-1)th operation, the ventilation resistance of the cooling heat exchanger remains high even when the defrosting operation ends, so the fan current ic at the start of cooling operation is larger than ia. In conventional technology, the fan current ic at the start of cooling operation is used as the reference value base, so even if frost actually exists, the system determines that no frost exists and starts operation accordingly. Therefore, when the difference value x reaches the threshold value d, the estimated amount of frost is mf, but the actual amount of frost increases to mf2, exceeding mf. Thus, in conventional technology, the actual amount of frost may be greater than expected. Furthermore, since the amount of frost is considered to be large in this case, not only is there a possibility that residual frost will occur again even after defrosting operation, but the absolute amount of residual frost is also likely to increase with subsequent operation. In other words, once this state occurs, the residual frost gradually increases, which may lead to a decrease in the heat transfer performance of the cooling heat exchanger and an increase in the temperature inside the freezer due to insufficient cooling performance.

[0031] As described above, in the conventional technology, it is possible to estimate the amount of frost formed during cooling operation even when there is residual frost, but it may not be possible to appropriately suppress the actual amount of frost to mf. Furthermore, it is thought that it is not easy to perform appropriate management that takes into account not only the frost formed on the cooling heat exchanger but also the frost formed around it.

[0032] The process according to this embodiment for dealing with such a problem will be described with reference to an example of a control flowchart shown in FIG. 4 and operation examples shown in FIGS.

[0033] In this embodiment, the control unit (more specifically, the defrost determination processing unit 21) acquires the fan current i from the current sensor 20 when the cooling operation starts (S401, S402). The control unit then compares the fan current i with a reference value Prebase, which is the previous reference current value (S403). If the fan current i is equal to or less than the previous reference value Prebase, the control unit updates the reference value base with the value of the fan current i (S404). Otherwise, the control unit maintains the reference value base at the previous reference value Prebase (S405).

[0034] An example of the operation of S403 to S405 will be described with reference to Fig. 5. In the example of Fig. 5, the fan current ib at the start of the (n-1)th cooling operation is compared with the previous reference value base(n-2), and since the two values ​​are equal, the new reference value base(n-1) is updated with the fan current ib (S403, S404).

[0035] On the other hand, in the nth time when residual frost occurs, the value of the fan current ic at the start of cooling operation is greater than the previous reference value base(n-1), so the previous reference value base(n-1) is used as the new reference value base(n) for the nth time (S403, S405), rather than the fan current ic. Therefore, the difference value x at the start of cooling operation is not 0, but is a value corresponding to the amount of residual frost. Therefore, even when residual frost occurs, the amount of frost can be accurately estimated, and a discrepancy between the estimated amount of frost and the actual amount of frost can be prevented.

[0036] 4, in this embodiment, the control unit periodically acquires the fan current i during cooling operation (S406) and compares it with a reference value base (S407). If the acquired fan current i is equal to or less than the reference value, the control unit updates the reference value to the value of the fan current i (S408). If not, the control unit does not change the reference value (S409).

[0037] An example of the operation of S406 to S409 will be described with reference to Fig. 6. In the example of Fig. 6, when the fan current ib at the start of the cooling operation in the (n-1)th operation is compared with the previous reference value base(n-2), the fan current ib is found to be smaller, so the reference value base(n-1) is updated to the fan current ib (S407, S408).

[0038] If the fan current ib decreases below the previous reference value for some reason, the control unit updates the reference value to the fan current ib and lowers it. In other words, if the reference value is not lowered, the difference value x starts from a negative value rather than zero, and when it reaches a predetermined difference value limit value d (threshold value d), the actual amount of frost may be greater than the estimated amount of frost. Therefore, in this embodiment, the reference value (e.g., the reference value base(n-1) in FIG. 6 ) is updated to a lower value and the difference value x from the updated reference value is calculated. This prevents such unexpected increases in the amount of frost and reduces estimation errors in the amount of frost due to changes in the surrounding environment. Various factors can be considered as factors that cause the reference value to decrease, such as when some frost remains on the surface of the cooling heat exchanger 13 until the end of the previous defrosting operation, when the amount of frost on the surrounding walls or the like decreases, or when the amount of distribution items 40 stored in the freezer compartment 50 decreases.

[0039] Furthermore, a decrease in the fan current value due to such factors does not necessarily occur only at the start of cooling operation. Therefore, in this embodiment, the reference value base can be periodically corrected not only at the start of cooling operation but also during cooling operation (loop LB in FIG. 4). Next, an example of this operation will be described with reference to FIG. 6.

[0040] As shown in FIG. 6 , in the nth operation, the fan current i c at the start of the cooling operation is equal to the previous reference value base(n-1). Therefore, as described above, the reference value base(n) is set equal to the fan current i c , i.e., base(n-1). However, if the value of the fan current i becomes equal to or less than the reference value base(n) during subsequent cooling operations, the reference value base is periodically corrected in loop LB, as described above, and the reference value is periodically updated (S407, S408). Therefore, not only at the start of the cooling operation, but also during the cooling operation, if the fan current i is equal to or less than the reference value base(n), the reference value base(n) is periodically updated, and the difference value x from the updated reference value is calculated.

[0041] This makes it possible to estimate the amount of frost taking into account changes in the environment within the freezer compartment 50, allowing for the construction of a more reliable frost monitoring system. For example, not only when residual frost forms on the cooling heat exchanger 13, but also when the load on the motor 11 for the fan 10 fluctuates due to changes in the ambient environmental conditions, the reference value base of the fan current i can be periodically updated so as to increase the estimated amount of frost. This makes it possible to avoid an underestimation of the amount of frost resulting in an excessive amount of frost, allowing for the construction of a more reliable system. Furthermore, even if an estimation error remains, the estimated amount of frost can be increased by lowering the reference value according to the present invention, allowing for the construction of a system with higher reliability than when the amount of frost is underestimated.

[0042] This process is performed, and a determination is periodically made as to whether the difference value x has reached the threshold value d (S410). When the difference value x has reached the threshold value d, the process for loop LB is terminated and the next process is executed.

[0043] 4, in this control flow, the final reference value base for the operation at the time when the difference value x becomes equal to or greater than the threshold value d is stored as the previous reference value Prebase (i.e., the previous reference value for the next operation) (S411). Then, after the defrosting operation is started and completed (S412, S413), the control returns to the cooling operation by loop LA, and the cooling operation is performed.

[0044] Therefore, the fan current value i at the start of cooling operation and during cooling operation is compared with the previous reference value Prebase or reference value base, and the reference value base is updated to the fan current i only when the fan current value i is equal to or less than the previous reference value Prebase or reference value base. In other words, based on the comparison of the fan current value i during cooling operation with the reference value, it is determined whether or not the reference value needs to be updated, and if there is a possibility that the amount of frost will be overestimated, it is determined that the reference value needs to be updated. This makes it possible to avoid erroneously estimating the reference value base and excessively underestimating the amount of frost, thereby enabling the construction of a more reliable system.

[0045] Therefore, according to this embodiment, there is provided a cold storage warehouse management system that controls a cooling device that is switchable between cooling operation and defrosting operation, and that includes: a current measurement unit that measures a current value of a blower that blows air for the cooling device; a memory unit that stores a reference current value that is a current value of the blower and serves as a reference for estimating the amount of frost; and a control unit that calculates a difference between the current value measured by the current measurement unit and the reference current value, and performs control to switch from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value, wherein the control unit determines whether or not the reference current value stored in the memory unit needs to be updated based on a comparison between the current value measured by the current measurement unit during cooling operation and the reference current value, and when it is determined that the reference current value needs to be updated, updates the reference current value based on the current value measured by the current measurement unit.

[0046] The memory unit stores load information relating to the relationship between the current value and the operating load of the fan 12. At the start of the cooling operation, the control unit may update the reference value base based on the load information between the fan current value i and the previous reference value Prebase, whichever has the smaller operating load of the fan 12. This enables updating the reference current value taking the operating load of the fan 12 into consideration. The load information may also be information indicating the relationship between the current value and the operating load of a blower other than the fan 12. The load information may also be information indicating, for example, a positive correlation between the current value and the operating load of the blower. In this case, an increase in the current value of the blower indicates an increase in the operating load, and thus an increase in the amount of frost formation can be estimated. For example, in the case of a propeller fan, the current value flowing through the fan 12 generally increases as the required differential pressure increases, so it is considered that there is a positive correlation between the fan current value and the operating load. Depending on the characteristics of the blower, there may also be a negative correlation between the current value and the operating load of the blower. In this case, if the current value of the blower decreases, it indicates an increase in the operating load, and therefore it can be assumed that the amount of frost has increased. In this case, if the current value of the blower is smaller than the previous reference value at the start of the cooling operation, the previous reference value may be adopted as the new reference value. Furthermore, if the current value of the blower is equal to or greater than the reference value during the cooling operation, the reference value may be periodically corrected and updated.

[0047] Second Embodiment Next, a second embodiment of the present invention will be described with reference to Figures 7 to 9. Note that descriptions that overlap with or are similar to the contents described above may be omitted.

[0048] FIG. 7 shows an example of a control flowchart in the second embodiment of the present invention. In contrast to the control flow in the first embodiment shown in FIG. 4, in which the reference value base is not increased, this embodiment differs in that the reference value base can be both increased and decreased. While the reference value base can be changed both upward and downward, a limit is set on the range of change of the reference value base. Furthermore, the reference value base can only be changed downward in the loop LB during cooling operation.

[0049] Therefore, in this embodiment, the reference value base may be increased only once during one control flow of loop LA, at the start of cooling operation. That is, the first process, which is a process for increasing the reference value base, may be performed only once during the start of cooling operation. On the other hand, the reference value base may be decreased a number of times, in addition to the one time at the start of cooling operation, by the number of times the process is performed in loop LB. That is, the second process, which is a process for decreasing the reference value base, may be performed a number of times, in addition to the one time at the start of cooling operation, by the number of times the process is performed in loop LB. Therefore, the frequency with which the reference value base decreases is higher than the frequency with which the reference value base increases. In this way, in this embodiment, while the reference value base is allowed to change both upward and downward, the range of change is limited. The frequency with which the flow causing the upward and downward changes is changed is varied, and the number of times the flow causing the downward change is increased, thereby improving responsiveness to residual frost and environmental changes.

[0050] 7, in this embodiment, the control unit (specifically, the defrost determination processing unit 21) acquires the fan current i from the current sensor 20 at the start of the cooling operation (S701, S702) and compares it with a reference value Prebase, which is the reference current value at the start of the previous cooling operation (S703). If the fan current i is equal to or greater than the previous value Prebase, the control unit updates the reference value base by adding the smaller of the maximum value (Ux1) by which the set reference value is increased or the difference between the value of the fan current i at the start of the cooling operation and the previous reference value Prebase as the change amount to the previous reference value Prebase (S704). On the other hand, if the fan current i is smaller than the previous reference value Prebase, the control unit updates the reference value base by subtracting the smaller of the maximum value (Dx1) of the change amount by which the set reference value is lowered or the difference between the previous reference value Prebase and the value of the fan current i at the start of cooling operation from the previous reference value Prebase (S705).

[0051] In this embodiment, the control unit periodically acquires the fan current i during cooling operation (S706) and compares it with the reference value base (S707). If the acquired fan current i is equal to or greater than the reference value, the control unit calculates the difference value x without updating the reference value base (S708). On the other hand, if the acquired fan current i is smaller than the reference value, the control unit updates the reference value base by lowering it using the smaller of the maximum amount of change (Dx2) by which the set reference value is lowered or the difference between the reference value base and the fan current i, and calculates the difference value x from the updated reference value base (S709).

[0052] An example of the operation of S703 to S710 will be described with reference to Figures 8 and 9. First, an example of the operation of S704 (the operation of increasing the reference value base at the start of the cooling operation) will be described with reference to Figure 8.

[0053] FIG. 8 shows data from eight operations, from the (n-4)th to the (n+3)th operation, assuming that the load on the fan 12 increased due to some factor at the start of the nth operation. Possible factors for the increase in the load on the fan 12 include a sudden increase in the amount of goods 40 in the freezer compartment 50, or a sudden increase in the amount of frost 30 in the freezer compartment 50 due to high humidity conditions occurring when goods 40 are brought in. If these factors make it difficult for the air to flow through the surrounding environment, the fan current i increases even if no frost forms on the surface of the cooling heat exchanger 13. Therefore, it is desirable to use the increased fan current i as the reference value base. However, when the current value is high at the start of the cooling operation, it is not easy to distinguish between a change in environmental conditions and residual frost.

[0054] Therefore, in this embodiment, a limit is placed on the amount of change in the reference value base, allowing appropriate measures to be taken. Specifically, as described above, the maximum amount of change is predetermined as Ux1. Then, the smaller of the value Ux1 and the difference between the fan current value i at the start of the cooling operation and the previous reference value Prebase is added to the reference value Prebase as the amount of change. Therefore, in the example shown in FIG. 8 , when the fan current value ia at the start of the nth cooling operation increases, the difference between the fan current value ia and the previous reference value Prebase is compared with the predetermined maximum amount of change Ux1. If the difference is greater than Ux1, the reference value base is increased by Ux1 from the previous reference value Prebase (S704).

[0055] In this case, the estimated amount of frost will not be estimated lower than the actual amount of frost. Furthermore, by repeating this operation (by gradually increasing the reference value base each time defrosting is performed), the reference value base gradually approaches an appropriate value, so even if a small amount of frost may occur transiently, there is no concern that this amount of frost will become excessive. Therefore, the reference value base can be corrected to an appropriate reference value so that the amount of frost does not become excessive.

[0056] In addition, although the present embodiment illustrates an example in which frost buildup on the ceiling and wall surfaces increases rapidly, if the change is gradual and the frost grows over a long period of time, the difference between the estimated amount of frost and the actual amount of frost is small. Thus, even if the difference between the estimated amount of frost and the actual amount of frost is small, by appropriately setting the value of the change amount Ux1, the reference value base can be adjusted to follow the influence of the frost growth.

[0057] Although there is a risk in raising the reference value when residual frost occurs, this risk can be minimized by reducing the amount of change in the reference value per change. Generally, it takes time for frost to grow, so this risk can be almost eliminated by setting the amount of change Ux1 to, for example, the same level as the detection accuracy of the fan current (for example, 0.1 A).

[0058] Next, with reference to FIG. 9, an example of the operation related to S705 (operation of lowering the reference value base at the start of cooling operation) and an example of the operation related to S709 (operation of lowering the reference value base during cooling operation) will be described.

[0059] If frost grows on the wall surface or the like, it may hinder the flow of air to the cooling heat exchanger 13, so for example, frost removal may be performed as part of maintenance work. In such a case, unlike frost growth, the frost is removed in a short period of time, which makes it easier for air to circulate inside the freezer compartment and reduces the load on the fan, resulting in a significant drop in the fan current i.

[0060] In this embodiment, in order to cope with such a case, a limit is set so that the value does not fall below a predetermined maximum value of change Dx1 immediately after the start of cooling operation, and the reference value base is updated up to Dx1 (S705). If this change is insufficient, the control unit gradually updates the reference value base by comparing it with the predetermined maximum value of change Dx2 each time it periodically acquires the fan current value i (S709).

[0061] FIG. 9 shows an example of operation when the fan current value ia at the start of the nth operation is significantly lower than the previous reference value base(n-1). In this case, the difference between the fan current value ia and the previous reference value base(n-1) is greater than the maximum change amount Dx1, so the cooling operation is started with a reference value base(n) that is Dx1 lower than the previous reference value base(n-1). Then, after dt time, i.e., when the fan current is acquired again, the deviation from base(n) is still large, so the reference value base(n) drops by the maximum change amount Dx2. By repeating this operation every dt time (periodically), the reference value base(n) reaches its lower limit (i.e., the same value as the fan current).

[0062] Here, the cooling operation time before the defrosting operation starts is, for example, about 10 hours per operation, while the control period dt is very short, about 1 minute. Therefore, even if the reference value base(n) needs to be repeated several times until it drops to a predetermined value, frost does not grow during that time, and even if this operation is repeated several times, there is almost no error in the estimation of the amount of frost. Furthermore, setting Dx2 prevents a sudden drop in the reference value base due to the influence of noise.

[0063] According to this embodiment, it is possible to correct the reference value of the fan current not only when residual frost occurs, but also when frost grows in the surrounding environment, or conversely, when the frost disappears from the surrounding environment, thereby enabling flexible response to changes in the environment within the freezer compartment 50.

[0064] As explained above, when the difference value x reaches the threshold value d, the process exits from loop LB (S710), the reference value Prebase is stored as the previous reference value (S711), defrosting operation is started (S712), and the defrosting operation ends (S713).

[0065] Third Embodiment Next, a third embodiment of the present invention will be described with reference to Figures 10 to 13. Note that descriptions that overlap with or are similar to the contents described above may be omitted.

[0066] 10 shows an example of a control flowchart in the third embodiment of the present invention. This embodiment is substantially the same control flow as the second embodiment before frost formation, i.e., while the maximum difference xmax is 0 (i.e., S1008 to S1010 in FIG. 10). However, the main difference is that the control flow (S1011 to S1015) is added when the maximum difference xmax is greater than 0 in loop LB, i.e., after frost formation.

[0067] The maximum difference xmax here is the maximum value of the difference x from the start of the defrosting operation until the next defrosting operation, i.e., the maximum value of the difference x during one pass through loop LA. At the end of loop LB, it is periodically updated to a larger value compared with the difference x (S1016), and when the difference x exceeds the threshold value d and loop LB is exited (S1017), the maximum difference xmax is reset to 0 (S1018).

[0068] The added control flow (S1011 to S1015) will be described with reference to Fig. 10. After frost formation, i.e., when the maximum difference xmax is greater than 0 (S1007), a control flow is executed in which the calculated difference value x is compared with the maximum difference xmax. Normally, when the amount of frost gradually increases, the difference value x gradually increases. However, this control flow is a control flow for dealing with the opposite case where the difference value x decreases.

[0069] In this control flow, the control unit calculates a difference value x as the difference between the fan current i and a reference value base (S1011). If the difference value x becomes smaller than the previous maximum difference value xmax (S1012), the control unit calculates the difference Delta between them (S1013). If the difference Delta is equal to or greater than a predetermined threshold value Xx (S1014), the control unit reduces the reference value base by the difference Delta and simultaneously recalculates the difference value x using the new reference value base (S1015). Thus, by the processes of S1011 to S1015, the difference value x is updated to the same value as the maximum difference xmax.

[0070] Next, an example of the operation of S1011 to S1015 (updating the difference value after frost formation) will be described with reference to FIG.

[0071] 11, the (n-2)th and (n-1)th operations are the same as those shown in Fig. 4, etc. In the nth cooling operation, the fan current ic at the start of the cooling operation is equal to the previous reference value base(n-1), so the control unit starts the cooling operation with the fan current ic0 as the new reference value base(n), and periodically calculates the estimated amount of frost from the difference value x.

[0072] In this operation example, it is assumed that the fan current suddenly drops by h from ic1 to ic2 at a certain point in time F. Various factors can be considered as the cause of such a drop, such as a drastic decrease in the amount of goods stored or the removal of frost around the cooler in a relatively short time due to maintenance, etc. When such an event occurs, the fan current drops significantly even though the amount of frost on the cooling heat exchanger 13 has not decreased.

[0073] If the reference value base is not corrected, the estimated amount of frost will be based on the difference value x, and so the estimated amount of frost will drop sharply as shown by the dashed line in Fig. 11, resulting in a large discrepancy between the estimated amount of frost and the actual amount of frost. Therefore, in this embodiment, a process is added to lower the reference value base(n) by the amount of this change.

[0074] Specifically, the control unit compares the difference value x = ic2 - ic0 (first difference value) with the maximum difference value xmax = ic1 - ic0 (second difference value) up to that point (S1012). If the difference value x is smaller than the maximum difference value xmax, the control unit calculates the difference between the maximum difference value xmax and the difference value x (S1013). If the calculated difference is equal to or greater than a predetermined threshold value Xx (S1014), the control unit performs processing to lower the reference value base(n) by the change in the difference value h (S1015). While the example described here is one in which the reference value base(n) is lowered by the change in the difference value h (i.e., the difference between the first difference value and the second difference value), as an example, the reference value base(n) may be lowered by a value smaller than the change in the difference value h.

[0075] By adding this process, even if the fan current drops significantly due to the influence of the surrounding environment, the amount of frost can be correctly estimated by lowering the reference value "base" by the amount of this change.

[0076] As described above, according to this embodiment, not only when residual frost occurs but also when the current value fluctuates significantly due to changes in the surrounding environment, the amount of frost can be accurately estimated in response to these changes, making it possible to start a defrosting operation at an appropriate timing depending on the amount of frost. Therefore, in control that starts a defrosting operation when the cooling operation time reaches a predetermined time, there is a problem that the defrosting operation is often started when the actual amount of frost is low. However, in this embodiment, the start of the defrosting operation can be determined at an appropriate timing depending on the amount of frost, making it possible to avoid starting a defrosting operation when the actual amount of frost is low. This makes it possible to reduce the number of defrosting operations that would otherwise be a thermal load in the freezer compartment 50, thereby enabling control with improved energy efficiency. Therefore, by applying this embodiment, a highly reliable and energy-efficient monitoring system for a refrigerated warehouse can be constructed.

[0077] In this embodiment, the processes of S1001 to S1005 and S1019 to S1020 are the same as those described above, and therefore the description thereof will be omitted.

[0078] As described above, frost on the walls and floors around the cooler 10 makes it difficult for air to flow, so in a refrigerated warehouse, a manager periodically monitors the interior of the refrigerated warehouse to check for excessive frost buildup and, if necessary, removes the frost. Whether or not this maintenance work is necessary is considered to be, for example, left to the discretion of the manager.

[0079] As described in the embodiment, the reference value base for estimating the amount of frost formation can be changed to follow changes in the surrounding environment. Therefore, by storing the reference value base for a long period of time, it becomes possible to see (understand) changes over time. Therefore, it is possible to use the stored reference value base as an index representing the amount of frost formation in the surrounding environment.

[0080] FIG. 12 shows an example of time-series changes in the reference value base. The reference value base obtained in this example gradually increases over time as frost grows in the surrounding environment. Then, by performing the above-described maintenance at time F1, the reference value base decreases, and then gradually increases again as the frost grows. This behavior is repeated. Therefore, by setting an upper limit bmax for the reference value base and, for example, setting in advance that maintenance should be performed when the reference value base exceeds the upper limit bmax, it becomes possible to determine whether maintenance is necessary based on data rather than the subjective judgment of the administrator.

[0081] Maintenance to remove frost is performed in the low-temperature environment of a refrigerated warehouse, placing a significant burden on workers. However, the need for this work can be quantitatively determined based on data, allowing for efficient work planning and execution using this data, minimizing fluctuations in the amount of frost that occurs during the work. Furthermore, the number of workers required and the amount of work time can be estimated more accurately, making management easier. Another benefit is that the work of monitoring the frost status can be simplified. Furthermore, as the amount of frost in the surrounding environment increases, fan current increases. From an energy-saving perspective, it is better to have less frost, but frequent maintenance work increases labor costs, so it is necessary to strike an appropriate balance.

[0082] Since the increase in power consumption is proportional to the area of ​​the dashed line in FIG. 12 , bmax may be determined so that maintenance can be performed at an appropriate time by comparing it with the operating costs, for example. Furthermore, visualizing the fluctuations in the reference value base as shown in FIG. 12 makes it easier to predict when maintenance will be required, which has the advantage of simplifying management. From this perspective, the control unit may output data related to the reference value base to an appropriate display device. For example, data related to the change in the reference value base over time may be output, as shown in FIG. 12 .

[0083] Here, the display format is not particularly limited, and for example, a graph may be displayed as shown in FIG. 12, or the reference value base for each predetermined time period may be displayed in a table format.

[0084] The control unit may also determine whether bmax is being approached by performing a threshold judgment, and may cause a warning device (e.g., a lamp or buzzer) to output a warning to that effect when bmax is approached. The control unit may also cause the warning device to output a warning when bmax is reached. That is, the control unit may issue a notification when the reference current value exceeds a predetermined threshold. The warning by the warning device may be issued in conjunction with or instead of a display on the display device.

[0085] In this way, it is possible to construct a highly reliable and energy-efficient cold storage management system that can not only correctly estimate the amount of frost and appropriately control the timing to start defrosting operation, but also simultaneously estimate the state of frost in the environment surrounding the cooler and determine whether maintenance is necessary.This not only reduces the burden on the manager, but also makes it possible to construct a cold storage management system that can provide the manager with information that is useful for determining the appropriate maintenance frequency, including work costs, and formulating a work plan.

[0086] The present invention is not limited to the above description and includes various modifications. For example, it is possible to add, delete, or replace part of the configuration of the embodiment with other configurations.

[0087] As shown in FIG. 13 , the defrost determination processing unit 21 (defrost determination processing device) can be configured as a device including, for example, a processor 101, a storage unit 102, an input unit 103, an output unit 104, and a display device 105. Here, the input unit 103 is configured as an input interface to which a measurement value detected by a current sensor is input, and the output unit 104 is configured as an output interface to output a control signal to the outside for appropriately operating the cooler 10. The processor 101 executes the above-described processing based on the measurement value from the current sensor and the reference current value stored in the storage unit 102, and outputs a control signal from the output unit 104 for appropriately operating the cooler 10. The processor 101 can also display the above-described data (e.g., data related to the reference value base) on the display device 105. Note that, although the defrost determination processing unit 21 includes the display device 105 in this example, the display device 105 may be provided external to the defrost determination processing unit 21.

[0088] The refrigeration apparatus 1 (refrigerated warehouse management system) only needs to be able to execute predetermined operations, and the processor having the processing function may be incorporated into the defrost determination processing unit 21 as in the example of Fig. 13, or may be arranged outside the defrost determination processing unit 21. Similarly, the storage unit may be incorporated into the defrost determination processing unit 21, or may be arranged outside the defrost determination processing unit 21.

[0089] The processor may be any device capable of executing predetermined processing, and may be configured using, for example, a CPU (Central Processing Unit), a microprocessor, etc. The storage unit may be any device capable of appropriately storing data used in the predetermined processing (for example, the previous reference value prebase, a program used to execute the predetermined processing, etc.), and may be configured using an HDD (Hard Disk Drive), ROM (Read Only Memory), etc. Alternatively, a RAM (Random Access Memory) may be used as appropriate.

[0090] An example has been described in which the cooler 10 is used as the cooling means (cooling device), but as long as the freezer can be appropriately frozen and stored, any appropriate device such as an industrial freezer may be used as the cooling means (cooling device).

[0091] If no display is required, the display device may be omitted.

[0092] The process of the flowchart described above is merely an example, and the control flow can be modified as appropriate. For example, a control flow such as that shown in FIG. 14 may be executed. This control flow (S1401 to S1418) is similar to the control flow shown in FIG. 10 described in the third embodiment, but differs mainly in that in loop LB, in addition to the process of updating the difference value x, a process of comparing the fan current value i with the reference value base is periodically executed regardless of whether frost has formed.

[0093] Furthermore, by using a highly reliable cold storage warehouse management system capable of accurately estimating the amount of frost as described above, it becomes possible to grasp the frost state and estimate the time for defrosting operation more accurately. Based on such information, it becomes possible to appropriately manage the power consumption of the cold storage warehouse, which contributes to cost reduction by reducing the amount of power used in the cold storage warehouse. It can also contribute to improved energy efficiency. Furthermore, applying the present invention to cold storage warehouse management can contribute to reducing greenhouse gas emissions throughout the cold storage warehouse.

[0094] Next, a system including the refrigeration device 1 described above, a work management server 201, and a power management server 202 will be described. This system is an example of a cold storage warehouse management system and can be used for solutions such as power management at a certain site. The work management server 201 includes a work planning system that creates and manages work information, including work details and work schedules, such as loading and unloading operations within the cold storage warehouses (50a-50d). The power management server 202 includes a power management system that monitors the power consumption status within the cold storage warehouses (50a-50d), manages the available power consumption, and creates power information, including information on power costs and power usage schedules (power schedules) for specific time periods. The work planning system may be implemented separately from the cold storage warehouse management system. In this case, the cold storage warehouse management system can be implemented as long as the cold storage warehouse management system is provided with information on work planned by the work planning system and information on the temperature rise inside the cold storage warehouse due to the opening and closing of the cold storage warehouse doors during loading and unloading operations. The available power consumption may also be information that manages power consumption during a specific time period so that it does not exceed a predetermined upper limit.

[0095] As described above, from the viewpoint that a defrosting operation is performed when the estimated amount of frost reaches a predetermined value, the control unit of the refrigeration apparatus 1 specifies a first defrosting operation schedule in which a defrosting operation is performed. Here, as an example, the control unit specifies a time until the estimated amount of frost reaches the predetermined value based on the current estimated amount of frost. After the specified time has elapsed, the control unit can set a first defrosting operation schedule in which the cooler 10 performs a defrosting operation.

[0096] Here, if the time for performing the defrosting operation according to the first defrosting operation schedule overlaps with a time when the amount of work, such as the loading and unloading of goods stored in the freezer warehouse, is greater than a predetermined amount, the temperature inside the freezer warehouse may rise due to the loading and unloading of goods while the interior cannot be cooled during the defrosting operation. In this case, if the first defrosting operation schedule cannot be changed, it is advisable to lower the temperature of the freezer warehouse below the initial set temperature before performing the defrosting operation. This makes it possible to maintain the temperature of the freezer warehouse even if outside air enters due to the loading and unloading of goods, without changing the first defrosting operation schedule. Furthermore, if multiple coolers 10 are installed, the cooler 10 that is not performing the defrosting operation can also perform the above processing.

[0097] The control unit of the refrigeration system 1 may determine a second defrosting schedule based on work information acquired from the work management server 201, including the work schedule and the work time when the doors of the refrigerated warehouse are opened and closed depending on the amount of goods being transported into and out of the refrigerated warehouse. This reduces the temperature rise inside the refrigerated warehouse caused by the simultaneous inflow of heat from the defrosting operation and the load caused by the work inside the refrigerated warehouse, thereby contributing to improved storage quality and energy efficiency in the refrigerated warehouse. Furthermore, the work information includes not only the time when the doors of the refrigerated warehouse are opened and closed, but also the number of times the doors are opened and closed. Since the load on the cooler increases when the temperature inside the refrigerated warehouse rises due to the loading and unloading of goods, it is desirable to control the defrosting operation so that it ends before the time when goods are loaded and unloaded as much as possible. While the defrosting operation of the cooler 10 is preferably performed during a time when goods are not being loaded or unloaded, it is also desirable to perform the operation during a time period when goods are loaded and unloaded less frequently than a predetermined time or a predetermined number of times. Furthermore, it is also desirable to perform the defrosting operation not only during a time period when goods are loaded and unloaded less frequently than a predetermined time or a predetermined number of times, but also during a time period when the outside air temperature is lower than a predetermined temperature. By combining and comprehensively evaluating the outside air temperature and the time or number of times goods are brought in and out, and selecting a time period when the temperature in the freezer warehouse is less likely to rise, more efficient defrosting operation can be performed.

[0098] Furthermore, from the perspective of power consumption, it is conceivable that the power consumption during defrosting operation may be greater than that during cooling operation, which maintains a constant temperature in a refrigerated warehouse. This is the case when defrosting operation is performed by blowing warm air through a frosted cooling fan. For example, in a warehouse equipped with multiple coolers 10, when the temperature state is stable or fluctuating little, cooling operation may be performed using only a number of coolers that can ensure the cooling capacity necessary to maintain the stable or fluctuating state, while the other coolers are performing defrosting operation or are on standby. In such cases, power consumption may be greater during periods when other coolers are performing defrosting operation than during periods when other coolers are on standby. Therefore, if periods during which cargo is being loaded and unloaded, which require a large amount of power for cooling, overlap with periods during which other coolers are performing defrosting operation, peak power consumption may increase during certain periods.

[0099] Therefore, the control unit may acquire information on the power consumption during peak power consumption in the area where the cold storage warehouse is installed from the power management server 202, which manages the power consumption in the area, and perform control to specify a schedule in which defrosting operation is not performed during the time period corresponding to the peak power consumption. That is, when the control unit determines that defrosting operation is necessary, it further determines whether the time period for which a first defrosting operation schedule for performing defrosting operation is specified overlaps with the peak power consumption, and sets and controls a second defrosting operation schedule so that defrosting operation is performed during a time period different from the peak power consumption. This avoids performing defrosting operation, which consumes more power than cooling operation during peak power consumption, thereby contributing to preventing an increase in the power baseload. In other words, reducing the use of thermal power generation and other sources of power generation as a baseload adjustment capability can contribute to reducing greenhouse gas emissions. In the above example, the overlap between the peak power consumption time period and the defrosting operation schedule is determined. However, a manager or other person may set a time period in advance in which defrosting operation is not performed, regardless of the peak power consumption.

[0100] Furthermore, when the control unit calculates the increase in the amount of frost and determines that a defrosting operation is required, if there is a time period before or after the initial time period during which the defrosting operation is to be performed in which the number of times or duration of door opening and closing of the freezer warehouse is less than in the initial time period, the defrosting operation may be performed during that time period. This reduces temperature changes inside the freezer warehouse and reduces the overall power consumption of the freezer warehouse. In other words, when a first defrosting operation schedule is specified, if a time period with little temperature change inside the freezer warehouse can be specified before and after the first defrosting operation schedule based on work information and outside temperature information, the time period before or after that time period is specified as the second defrosting operation schedule.

[0101] In addition, if there is a time period before or after the initial time period when the outside temperature of the freezer warehouse is lower than the initial time period when defrosting operation is to be performed, it is advisable to perform defrosting operation during that lower time period. By performing defrosting operation during a time period when the temperature rise inside the freezer warehouse is low, normal cooling operation can be performed during a time period when the temperature rise inside the freezer warehouse is high, making it less likely that the temperature inside the freezer warehouse will change. The time period when defrosting operation is performed can also be changed taking into account both the time period when the number of times or duration of door opening and closing is low and the time period when the temperature rise inside the warehouse is low, and performing defrosting operation during a time period that satisfies both can further increase energy saving effects.

[0102] Furthermore, the control unit may take into account information on power costs included in the power information, and if there are time periods when power consumption costs are low, control the defrosting operation to be performed during those time periods.As an example, a first defrosting operation schedule for performing the defrosting operation is determined by determining whether the power consumption cost during the specified first time period exceeds a predetermined threshold, and if it exceeds the predetermined threshold, a second defrosting operation schedule is set and controlled so that the defrosting operation is performed during a second time period when the power consumption cost is lower than that during the first time period.During time periods when power is low, surplus power can also be used for power generation, which may further reduce the environmental load.

[0103] In this way, the cold storage management system can use information from the power management server 202 to identify a defrosting operation schedule that takes power consumption into consideration. Furthermore, from the perspective of reducing power consumption, it is possible to reduce the maximum power consumption through peak shifting. Consequently, it is possible to reduce the impact of the cold storage as a whole on the power generation peak of the power plant, thereby reducing the amount of greenhouse gases generated overall.

[0104] In this explanation, an example has been described in which the refrigerated warehouse management system specifies a defrosting operation schedule for multiple warehouses at one location, but this system can also be operated for multiple locations. In this case, the work management server 201 and the power management server 202 may be configured to be able to communicate with the refrigeration equipment 1 at each location. The work management server 201 and the power management server 202 may be able to communicate with the work planning system and power management system that manage the locations, and may communicate with each other to obtain information about the respective locations.

[0105] A display device may be arranged at a base, and information used for selecting whether to select the defrosting operation in advance to a time period when the number of goods loading and unloading operations is greater than a predetermined value, or to select the defrosting operation after the loading and unloading operations, may be output to the display device, and a schedule for the defrosting operation may be specified according to the selection input by an administrator of the cold storage warehouse management system as a representative user. Note that the user's input is performed using an appropriate input device. Furthermore, information on the timing to perform the defrosting operation may be output to the display device, and a schedule for the defrosting operation based on the timing or time period permitted by the user may be specified using an appropriate input device. Meanwhile, the control unit may automatically perform the defrosting operation according to the specified schedule.

[0106] Next, an example of a refrigerated warehouse management system will be described with reference to Fig. 15. As explained above, this system can be used for solutions such as power management at a certain base. Note that explanations that are the same as those already explained may be omitted.

[0107] 15, this system includes an integrated management system 301 configured to be able to communicate with each base via a network, and does not include the work management server 201 and power management server 202 described above. The integrated management system 301 performs integrated management of each base based on data from each base.

[0108] First, the configuration of the base side of this system, i.e., the cold storage warehouse side, will be described. In this example, the cold storage warehouse operates one or more refrigeration units 1 and includes a work management unit 311 and a power management unit 312. The work management unit 311 stores base-specific work management data 317, which is data related to work management for each base. The base-specific work management data 317 is, for example, information on work such as loading and unloading of goods at the base and storage information for items that are the subject of work. The power management unit 312 stores base-specific power management data 318, which is data related to power management for each base. The base-specific power management data 318 is, for example, information on the amount of power consumed at the base and the power usage status of the refrigeration units 1. The work management unit 311 and the power management unit 312 can be configured using appropriate storage devices, but may also be configured, for example, by a server that manages the bases.

[0109] Next, the integrated management system 301 will be described in detail. The integrated management system 301 includes a processing unit 302 and a storage unit 303. The processing unit 302 can be configured using an appropriate processing device and performs data processing using data from each base. The storage unit 303 is configured using an appropriate storage device and stores work management data 307, which is data related to work management, and power management data 308, which is data related to power management. Here, the work management data 307 is data obtained by appropriately compiling the base-specific work management data 317 from each base. The power management data 308 is data obtained by appropriately compiling the base-specific power management data 318 from each base.

[0110] The integrated management system 301 manages the amount of power consumption at each base and creates a power usage plan and a work plan based on the acquired power management data 308 and work management data 307. Furthermore, as described above, the integrated management system 301 specifies a defrosting operation schedule based on the power usage plan.

[0111] As an example of use in a power management solution for multiple bases, the integrated management system 301 may specify a defrosting operation schedule that reduces overall power consumption based on the power management data 308. Here, as described above, the integrated management system 301 can specify a time period in which defrosting operation is not performed so that the defrosting operation time period does not overlap with a time period in which there is a lot of cargo being carried in and out. Furthermore, a schedule in which defrosting operation is not performed during a time period corresponding to peak power consumption at multiple bases may be specified. In particular, when specifying a schedule in which defrosting operation is not performed during a time period corresponding to peak power consumption at multiple bases, a schedule may be specified in which defrosting operation is not performed at one or more bases and defrosting operation is performed at other bases, as long as the total power consumption does not exceed the peak power. In this case, multiple candidate combinations of defrosting operation schedules, i.e., at which bases (or coolers) defrosting operation is performed during a predetermined period at multiple bases, may be specified. Then, a display screen (display unit) for the administrator may display selectable schedule candidates for which bases defrost operation is performed. In this case, to support the manager's selection, the display screen may output the work plan, power usage plan, power cost, and the quantity and type of goods handled at each location. For example, for each schedule candidate, information on the power consumption efficiency or power cost at each location may be calculated and displayed together with the schedule candidate. This provides more appropriate support for the manager's selection. On the other hand, the integrated management system 301 may automatically determine the location at which the defrosting operation should be performed based on predetermined criteria.

[0112] Furthermore, if there is a time period during which power consumption costs are low, the integrated management system 301 may specify a schedule for performing defrosting operation during that time period.

[0113] In addition, the integrated management system 301 may determine which bases should be prioritized for cooling based on the amount and type of goods handled at each base, and may specify a schedule in which defrosting operation is given priority to bases that do not.

[0114] The data planned and identified by the integrated management system 301 may be displayed on an appropriate display device located at the base. Also, in the same manner as described above, a defrosting operation schedule may be identified in accordance with an input from an administrator of the management system of the cold storage warehouse.

[0115] REFRIGERATION SYSTEM 1 REFRIGERATION DEVICE (REFRIGERATED WAREHOUSE MANAGEMENT SYSTEM) 10 COOLER (COOLING DEVICE) 12 FAN (BLOWER) 15 OPERATION CONTROL PROCESSING PART 20 CURRENT SENSOR (CURRENT MEASURING PART) 21 DEFROSTING DETERMINATION PROCESSING PART (DEFROSTING DETERMINATION PROCESSING DEVICE) 201 WORK MANAGEMENT SERVER 202 POWER MANAGEMENT SERVER 301 INTEGRATION MANAGEMENT SYSTEM

Claims

1. A cold storage management system that controls a cooling device that can switch between cooling operation and defrosting operation, comprising: a current measurement unit that measures a current value of a blower that blows air for the cooling device; a memory unit that stores a reference current value that is a current value of the blower and serves as a reference for estimating the amount of frost formation during cooling operation; and a control unit that calculates a difference between the current value measured by the current measurement unit and the reference current value, and performs control to switch from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value, wherein the control unit updates the reference current value stored in the memory unit based on the current value measured by the current measurement unit during cooling operation and the reference current value.

2. A refrigerated warehouse management system as claimed in claim 1, wherein the memory unit stores load information which is information relating to the current value of the blower and the operating load, and the control unit, when updating the reference current value stored in the memory unit, updates the reference current value based on the load information to either the current value measured by the current measuring unit during cooling operation or the reference current value stored in the memory unit, whichever results in a smaller operating load on the blower.

3. A refrigerated warehouse management system as claimed in claim 1, wherein the blower is a propeller fan, and the control unit, when updating the reference current value stored in the memory unit, updates the reference current value to the smaller of the current value measured by the current measurement unit during cooling operation and the reference current value stored in the memory unit.

4. A refrigerated warehouse management system as claimed in claim 1, characterized in that the control unit updates the reference current value by varying the frequency at which the reference current value is increased and decreased.

5. A refrigerated warehouse management system as claimed in claim 4, wherein the blower is a propeller fan, and the control unit is capable of executing a first process of updating the reference current value to a larger value and a second process of updating the reference current value to a smaller value, and the reference current value is updated by performing the second process more frequently than the first process.

6. A cold storage management system according to claim 1, wherein the control unit compares a first difference value, which is the difference value between the current value of the blower at a predetermined timing and the reference current value, with a second difference value, which is the maximum difference value between the current value of the blower and the reference current value from the start of cooling operation until the predetermined timing, and updates the reference current value to be lower than the previous reference current value if the first difference value is smaller than the second difference value by a predetermined threshold or more.

7. A refrigerated warehouse management system as claimed in claim 6, characterized in that the control unit updates the reference current value by lowering it by the difference between the magnitude of the first difference value and the magnitude of the second difference value.

8. A refrigerated warehouse management system as set forth in any one of claims 4 to 6, wherein the control unit controls an alarm device to notify a manager that the amount of frost has exceeded a specified amount when the reference current value exceeds a predetermined threshold.

9. A refrigerated warehouse management system according to any one of claims 4 to 6, characterized in that the memory unit stores an updated reference current value, and the control unit controls a display device to display time-series changes in the reference current value.

10. A refrigerated warehouse management system as claimed in claim 1, characterized in that the control unit determines a schedule for the cooling device to perform defrosting operation based on the result of estimating the current frosting state.

11. A refrigerated warehouse management system as claimed in claim 10, characterized in that the control unit acquires work information for one or more refrigerated warehouses, and further determines a schedule for the cooling device to perform defrosting operation based on the work information.

12. A refrigerated warehouse management system as claimed in claim 10, characterized in that the control unit acquires power information for one or more refrigerated warehouses, and further determines a schedule for the cooling device to perform defrosting operation based on the power information.

13. A refrigerated warehouse management system as claimed in claim 11 or 12, characterized in that the control unit identifies information on a plurality of candidate schedules for the defrosting operation of the cooling devices in the one or more refrigerated warehouses, and causes the identified information to be selectably displayed on the display unit.

14. A defrost determination processing device that controls a cooling device that is capable of switching between cooling operation and defrosting operation and that adjusts the temperature inside a freezer warehouse, comprising: a memory unit that stores a reference current value that is a current value of a blower that blows air into the cooling device and serves as a reference for estimating the amount of frost formation during cooling operation; and a processor that calculates a difference between the current value of the blower and the reference current value, and performs control to switch from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value, wherein the processor updates the reference current value stored in the memory unit based on the current value of the blower during cooling operation and the reference current value.

15. A method for managing a freezer warehouse for adjusting the temperature inside the freezer warehouse by controlling a cooling device that can switch between cooling operation and defrosting operation, comprising the steps of: acquiring a current value of a blower that blows air for the cooling device; calculating a difference between the acquired current value and a reference current value that is the current value of the blower and serves as a reference for estimating the amount of frost formation during cooling operation; and switching from cooling operation to defrosting operation when the calculated difference value reaches a predetermined value; and updating the reference current value based on the current value acquired during cooling operation and the reference current value.

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