JP7407070B2 - Refrigerator system - Google Patents

Description

The present invention relates to a refrigerator system.

The refrigerator of the refrigerator system cools the heat medium sent from the chilled water load equipment and supplies the cooled heat medium to the chilled water load equipment (for example, Patent Document 1).

Japanese Patent Application Publication No. 2015-117888

The heat load in chilled water load equipment varies depending on the season and other factors. For example, in the summer, the heat load on the chilled water load equipment is high, and in the winter, the heat load on the chilled water load equipment is low. When the heat load fluctuates in this way, if the heat load is low, there is a risk that the refrigerator will be operated in vain, and if the heat load is high, there is a risk that the chilled water load equipment will run out of cold water.

In view of such problems, an object of the present invention is to provide a refrigerator system that can efficiently supply a cooled heat medium to chilled water load equipment even if the heat load fluctuates.

In order to solve the above problems, the refrigerator system of the present invention includes a refrigerator that cools the heat medium sent from the chilled water load equipment and supplies it to the chilled water load equipment, and a temperature of the heat medium sent to the chilled water load equipment. a load inlet temperature sensor that detects the load inlet temperature; a heat load derivation unit that derives the heat load in the chilled water load equipment; a set temperature that indicates a range of load inlet temperatures set to determine the number of operating chillers; The temperature level corresponding to the range is predetermined for each set temperature range according to the set value of the load inlet temperature, and the operating unit number control section determines the time period during which the temperature level is maintained at the current temperature level for a predetermined period of time. If the load inlet temperature acquired by the load inlet temperature sensor changes to a load inlet temperature belonging to another temperature level different from the current temperature level before the time elapses, the current operating number of chillers is maintained; If the load inlet temperature acquired by the load inlet temperature sensor belongs to the current temperature level even if the time during which the temperature level is maintained at the current temperature level has passed a predetermined period of time, the load inlet temperature acquired by the load inlet temperature sensor is If the derived number of operating units is equal to the current number of operating units, the current number of operating units of chillers is maintained, and the derived number of operating units is different from the current number of operating units. If so, the number of operating refrigerators is switched to the derived number of operating units .
In addition, the operation number control unit determines that a reduction set temperature, which is a set value of the load inlet temperature for reducing the number of operating chillers when the heat load is relatively low, is a reduction set temperature when the heat load is relatively high. If the load inlet temperature becomes lower than the reduction setting temperature corresponding to the heat load, the number of operating refrigerators may be reduced.

In order to solve the above problems, the refrigerator system of the present invention includes a refrigerator that cools the heat medium sent from the chilled water load equipment and supplies it to the chilled water load equipment, and a temperature of the heat medium sent to the chilled water load equipment. a load inlet temperature sensor that detects the load inlet temperature; a heat load derivation unit that derives the heat load in the chilled water load equipment; A number-of-operating units control section that changes the set value of the load inlet temperature, which is a reference for switching the number of operating units, depending on the heat load, and the number-of-operating units control unit reduces the number of operating chillers when the heat load is relatively low. The reduction setting temperature, which is the setting value of the load inlet temperature, is set relatively higher than the reduction setting temperature when the heat load is relatively high, and the load inlet temperature is less than the reduction setting temperature corresponding to the heat load. Therefore, the number of operating chillers will be reduced.

In addition, the operation number control unit determines that the increase set temperature, which is the set value of the load inlet temperature for increasing the number of operating chillers when the heat load is relatively low, is the increase set temperature when the heat load is relatively high. The number of operating refrigerators may be increased when the load inlet temperature becomes equal to or higher than the increase setting temperature corresponding to the heat load.

According to the present invention, even if the heat load fluctuates, it is possible to efficiently supply the cooled heat medium to the chilled water load equipment.

1 is a schematic diagram showing the configuration of a refrigerator system according to this embodiment. It is a figure showing an example of a 1st table and a 2nd table. It is a flowchart explaining the flow of operation of a thermal load derivation part. It is a flowchart explaining the flow of operation of an operation number control part.

Aspects of embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in these embodiments are merely illustrative to facilitate understanding of the invention, and do not limit the invention unless otherwise specified. In this specification and the drawings, elements with substantially the same functions and configurations are given the same reference numerals to omit redundant explanation, and elements not directly related to the present invention are omitted from illustration. do.

FIG. 1 is a schematic diagram showing the configuration of a refrigerator system 1 according to this embodiment. In Figure 1, the direction of the flow of the heat medium is shown by solid arrows, the direction of the flow of air that exchanges heat with the heat medium is shown by chain double-dashed arrows, and the direction of the flow of control signals is shown by dashed arrows. ing.

The refrigerator system 1 includes refrigerators 10a, 10b, 10c, cold water load equipment 12, expansion tank 14, piping 16a, 16b, 16c, 16d, 16e, 16f, 16g, 16h, 16i, cold water primary pumps 18a, 18b, 18c, a cold water secondary pump 20, a control valve 22, a pressure gauge 24, a flow meter 26, a load inlet temperature sensor 30, a load outlet temperature sensor 32, and a control section 34.

In the refrigerator system 1, three refrigerators 10a, 10b, and 10c are provided in parallel. Hereinafter, the refrigerators 10a, 10b, and 10c may be collectively referred to as the refrigerator 10. Note that the number of refrigerators 10 is not limited to three, and may be one, two, or four or more.

The refrigerator 10 is, for example, a turbo refrigerator. The refrigerator 10 cools the heat medium sent from the chilled water load facility 12 via the expansion tank 14 and supplies the cooled heat medium to the chilled water load facility 12 via the expansion tank 14 . The heat medium is, for example, water.

The cold water load equipment 12 is, for example, an air conditioner such as an air handling unit (AHU). Note that the cold water load equipment 12 is not limited to an air conditioner, and may be, for example, a heat exchanger. In the chilled water load equipment 12, heat exchange is performed using the heat medium supplied from the refrigerator 10. The heat medium after heat exchange is returned to the refrigerator 10.

Expansion tank 14 is a hollow container. The expansion tank 14 accommodates a heat medium. In addition, in FIG. 1, the heat medium in the expansion tank 14 is shown by hatching.

A partition plate 40 is provided inside the expansion tank 14 and stands vertically from the bottom surface. The upper end 42 of the partition plate 40 is spaced apart from the ceiling 44 of the expansion tank 14. The partition plate 40 partitions the inside of the expansion tank 14 into a first area A1 and a second area A2. The first area A1 and the second area A2 communicate with each other through a space between the upper end 42 of the partition plate 40 and the ceiling 44.

In the refrigerator system 1, the inside of the expansion tank 14 is partitioned by a partition plate 40 to form a first area A1 and a second area A2. However, the first area A1 and the second area may be formed by separate containers. Further, the container forming the first area A1 and the container forming the second area A2 may be communicated with each other.

The pipe 16a communicates between the heat medium outlet 50 of the refrigerator 10a and the first area A1 of the expansion tank 14, and also communicates the heat medium outlet 50 of the refrigerator 10b with the first area A1 of the expansion tank 14. , the outlet 50 of the heat medium in the refrigerator 10c and the first area A1 of the expansion tank 14 are communicated with each other. Specifically, the pipes 16a extend from each of the refrigerators 10a, 10b, and 10c, are collected into one pipe 16a, and reach the first area A1. The pipe 16a guides the heat medium cooled by the refrigerator 10 to the first area A1 of the expansion tank 14. The heat medium cooled by the refrigerator 10 is stored in the first area A1 of the expansion tank 14 .

The pipe 16b communicates the first area A1 of the expansion tank 14 with the secondary cold water pump 20. Piping 16c connects cold water secondary pump 20 and control valve 22. The piping 16d communicates the control valve 22 with the heat medium inlet 52 in the chilled water load equipment 12. The pipes 16b, 16c, and 16d guide the heat medium stored in the first area A1 to the cold water load equipment 12.

The secondary cold water pump 20 sends the heat medium in the first area A1 to the cold water load equipment 12. That is, the cold water secondary pump 20 sends the heat medium from the refrigerator 10 to the cold water load equipment 12 through the first area A1.

The control valve 22 can change the opening degree of the flow path in the pipes 16b, 16c, and 16d. The pressure gauge 24 is provided in the piping 16c located upstream of the flow of the heat medium than the control valve 22. The opening degree of the control valve 22 is changed according to the temperature of an air temperature sensor 72, which will be described later.

The flow meter 26 is provided, for example, in the piping 16c located downstream of the flow of the heat medium than the secondary cold water pump 20. The flow meter 26 detects the flow rate of the heat medium flowing through the pipe 16c. That is, the flow meter 26 detects the flow rate of the heat medium supplied to the cold water load equipment 12.

The pipe 16e communicates the heat medium outlet 54 in the cold water load equipment 12 with the second area A2 of the expansion tank 14. The pipe 16e guides the heat medium sent out from the cold water load equipment 12 to the second area A2 of the expansion tank 14. In the second area A2 of the expansion tank 14, the heat medium after being used in the cold water load equipment 12 is stored.

The piping 16f communicates between the second area A2 of the expansion tank 14 and the cold water primary pump 18a, and also connects the second area A2 of the expansion tank 14 with the cold water primary pump 18b. A2 and the cold water primary pump 18c are communicated. Specifically, the pipe 16f extends from the second area A2 of the expansion tank 14 and branches into three pipes in order, the first branch reaching the cold water primary pump 18a, and the second branch supplying the cold water 1. It reaches the next pump 18b, and the third branched pipe reaches the cold water primary pump 18c. The piping 16g communicates the cold water primary pump 18a with the heat medium inlet 56 of the refrigerator 10a. Piping 16h communicates between cold water primary pump 18b and heat medium inlet 56 in refrigerator 10b. Piping 16i communicates between cold water primary pump 18c and heat medium inlet 56 in refrigerator 10c. Pipes 16f, 16g, 16h, and 16i guide the heat medium stored in the second area A2 of the expansion tank 14 to the refrigerator 10.

Hereinafter, the cold water primary pumps 18a, 18b, and 18c may be collectively referred to as the cold water primary pump 18. The cold water primary pump 18 sends the heat medium in the second area A2 to the refrigerator 10. That is, the cold water primary pump 18 sends the heat medium from the cold water load equipment 12 to the refrigerator 10 through the second area A2.

In this way, in the refrigerator system 1, the heat medium circulates between the refrigerator 10 and the chilled water load equipment 12. The pipes 16a, 16b, 16c, 16d, 16e, 16f, 16g, 16h, and 16i function as circulation channels through which the heat medium flows. Further, the expansion tank 14 is provided in the circulation flow path of the heat medium between the refrigerator 10 and the cold water load equipment 12, and is a first area A1 that stores the heat medium supplied from the refrigerator 10 to the cold water load equipment 12. and a second area A2 that stores the heat medium sent from the chilled water load equipment 12 to the refrigerator 10.

A primary motor 60a is connected to the cold water primary pump 18a. A primary inverter 62a is connected to the primary motor 60a. The primary inverter 62a is connected to a commercial power source, converts power at a commercial frequency into power at a frequency according to a frequency command value instructed by the control unit 34, and supplies the power to the primary motor 60a. The primary motor 60a drives the cold water primary pump 18a at a rotational speed according to the frequency of the electric power supplied from the primary inverter 62a.

A primary motor 60b is connected to the cold water primary pump 18b. A primary inverter 62b is connected to the primary motor 60b. The primary inverter 62b is connected to a commercial power source, converts power at a commercial frequency into power at a frequency according to a frequency command value instructed by the control unit 34, and supplies the power to the primary motor 60b. The primary motor 60b drives the cold water primary pump 18b at a rotational speed according to the frequency of the electric power supplied from the primary inverter 62b.

A primary motor 60c is connected to the cold water primary pump 18c. A primary inverter 62c is connected to the primary motor 60c. The primary inverter 62c is connected to a commercial power source, converts power at a commercial frequency into power at a frequency according to a frequency command value instructed by the control unit 34, and supplies the power to the primary motor 60c. The primary motor 60c drives the cold water primary pump 18c at a rotational speed according to the frequency of the electric power supplied from the primary inverter 62c.

Hereinafter, the primary inverters 62a, 62b, and 62c may be collectively referred to as the primary inverter 62. Further, the primary motors 60a, 60b, and 60c may be collectively referred to as the primary motor 60. Further, the flow rate of the heat medium passing through the refrigerator 10 may be referred to as a primary flow rate. The primary flow rate follows the rotational speed of the primary cold water pump 18, that is, the frequency command value instructed to the primary inverter 62 (hereinafter sometimes simply referred to as the frequency command value of the primary inverter 62).

A secondary motor 64 is connected to the cold water secondary pump 20 . A secondary inverter 66 is connected to the secondary motor 64 . The secondary inverter 66 is connected to a commercial power source, converts power at a commercial frequency into power at a frequency according to a frequency command value instructed by the control unit 34, and supplies the power to the secondary motor 64. The secondary motor 64 drives the cold water secondary pump 20 at a rotational speed according to the frequency of the electric power supplied from the secondary inverter 66 .

Hereinafter, the flow rate of the heat medium passing through the chilled water load facility 12 may be referred to as a secondary flow rate. The secondary flow rate follows the rotational speed of the cold water secondary pump 20, that is, the frequency command value instructed to the secondary inverter 66.

For example, air (outside air) is introduced into the cold water load equipment 12. In the chilled water load equipment 12, heat exchange is performed between the heat medium supplied from the refrigerator 10 and the introduced air. Thereby, the temperature of the heat medium at the outlet 54 of the chilled water load facility 12 (after heat exchange) becomes higher than the temperature of the heat medium at the inlet 52 of the chilled water load facility 12 (before heat exchange).

The air heat-exchanged in the chilled water load equipment 12 is sent to the room 70, for example. Further, an air temperature sensor 72 is provided in the air flow path between the chilled water load equipment 12 and the room 70. The air temperature sensor 72 detects the temperature of the air after heat exchange in the chilled water load facility 12 .

A load inlet temperature sensor 30 is provided near the inlet 52 of the chilled water load equipment 12 in the piping 16d. The load inlet temperature sensor 30 detects the load inlet temperature, which is the temperature of the heat medium fed into the chilled water load equipment 12.

A load outlet temperature sensor 32 is provided near the outlet 54 of the chilled water load equipment 12 in the piping 16e. The load outlet temperature sensor 32 detects the load outlet temperature, which is the temperature of the heat medium sent out from the chilled water load equipment 12.

The control unit 34 is composed of a semiconductor integrated circuit including a ROM in which a central processing program and the like are stored, a RAM as a work area, and the like. The control unit 34 functions as a heat load derivation unit 82 and an operating number control unit 84 by executing a program.

Here, the temperature of the air introduced into the chilled water load facility 12 varies depending on the season, date and time, and the like. The control unit 34 controls the opening degree of the control valve 22 so that the temperature measured by the air temperature sensor 72 (the temperature of the air after heat exchange in the chilled water load equipment 12) is constant at a preset temperature.

When the opening degree of the control valve 22 changes, the pressure of the heat medium sent to the chilled water load equipment 12 changes. The control unit 34 controls the flow rate of the heat medium passing through the secondary cold water pump 20 (secondary flow rate) by controlling the frequency command value instructing the secondary inverter 66 so that the pressure of the pressure gauge 24 is constant. do. In this way, in the refrigerator system 1, the secondary flow rate varies depending on the temperature of the air introduced into the chilled water load equipment 12. That is, in the refrigerator system 1, the heat load on the chilled water load equipment 12 required to keep the temperature determined by the air temperature sensor 72 constant varies depending on the season, date and time, and the like.

The thermal load deriving unit 82 derives the temperature difference between the temperature measured by the load inlet temperature sensor 30 (load inlet temperature) and the temperature measured by the load outlet temperature sensor 32 (load outlet temperature). The thermal load deriving unit 82 derives the thermal load (kW) in the chilled water load equipment 12 based on the derived temperature difference and the flow rate (secondary flow rate) measured by the flow meter 26.

The operating number control unit 84 controls the number of operating refrigerators 10 based on the thermal load derived by the thermal load deriving unit 82 and the load inlet temperature measured by the load inlet temperature sensor 30.

Specifically, the operating number control unit 84 stores in advance a plurality of tables (for example, a first table and a second table) that differ depending on the height of the heat load. The operating number control unit 84 determines the number of operating refrigerators 10 using these tables. Note that the number of tables stored in the operating number control unit 84 is not limited to two, but may be three or more.

FIG. 2 is a diagram showing an example of a first table and a second table. FIG. 2(a) shows the first table, and FIG. 2(b) shows the second table. Note that the specific numerical values in the first table and the second table are not limited to the illustrated numerical values.

The first table and the second table are associated with the heat load on the chilled water load equipment 12, the temperature level of the load inlet temperature, the set temperature range of the load inlet temperature, and the number of operating refrigerators 10. The set temperature range of the load inlet temperature indicates a temperature range set to determine the number of operating refrigerators 10. The temperature level of the load inlet temperature is associated with each set temperature range, and gradually increases from the low temperature side to the high temperature side.

Regarding the number of operating refrigerators 10 in FIGS. 2(a) and 2(b), for convenience, only the case where the number of operating units changes from the current number of operating units is indicated, and the number of operating units changes to the current number of operating units. The notation when it is maintained is omitted. In the notation of the number of operating vehicles, the starting point side (left side) of the right arrow indicates the current number of operating vehicles, and the end point side (right side) indicates the number of operating vehicles after switching. For example, 0 → 1 indicates that the number of operating vehicles is switched from 0 to 1.

Further, for example, in the temperature level 5 of the first table, 1→2 and 0→1 are written together. This indicates that if the current load inlet temperature is in the range of temperature level 5 and the current number of operating units is 1, it will be switched to 2 units, and if the current number of operating units is 0, it will be switched to 1 unit. ing. Furthermore, as will be described later, when the number of operating vehicles is switched, the number of operating vehicles after switching is maintained for a predetermined period of time after the switching. In other words, even if 1→2 and 0→1 are written together, if the current number of operating vehicles is 0, the number of operating vehicles will not switch to 2 at once. On the other hand, as in temperature level 7 in the first table, 0 → 2 indicates that when the current number of operating machines is 0, the number of operating machines is suddenly switched to 2.

Further, for example, from temperature level 4 to temperature level 6 in the first table, 0→1 is written respectively. This indicates that the current number of operating units is 0, and the number of operating units will be switched to 1 regardless of whether the load inlet temperature becomes temperature level 4, temperature level 5, or temperature level 6.

Here, as will be described later, the switching of the number of operating units is not performed immediately when the load inlet temperature reaches the temperature level at which the number of operating units is switched, but is maintained at the temperature level at which the number of operating units is switched over a predetermined period of time. It is done in case. Therefore, for example, even if the current number of operating units is 0 and the load inlet temperature rises from temperature level 3 to temperature level 4 in the first table, the temperature will rise again within a predetermined time after belonging to temperature level 4. When the level increases to level 5, the number of operating vehicles is not switched from 0 to 1, but is maintained at 0. For example, when a predetermined period of time has elapsed since the load inlet temperature belonged to temperature level 5, the number of operating units is switched from 0 to 1. Note that even if the temperature level is changed from temperature level 4 to temperature level 5, if the command is the same, the control may maintain the predetermined time count at temperature level 4 at temperature level 5 as well.

In other words, even if the same switching pattern (for example, 0 → 1) that increases the number of operating units is written across multiple temperature levels (for example, from temperature level 4 to temperature level 6 in the first table), The number of operating units may not change on the low temperature side (low level side).

Furthermore, the present invention is not limited to the mode in which the number of operating vehicles is increased, but also the mode in which the number of operating vehicles is decreased. In other words, even if the same switching pattern (for example, 2 → 1) that reduces the number of operating units is displayed across multiple temperature levels (for example, temperature level 2 and temperature level 3 in the first table), side (high level side), the number of operating units may not change.

Further, assume that the current number of operating units is 0 and the load inlet temperature has risen from temperature level 3 to temperature level 7 in the first table. At this time, unless the load inlet temperature is maintained at temperature level 4, temperature level 5, and temperature level 6 for a predetermined period of time, the number of operating units is maintained at 0 until temperature level 7 is reached. For example, when a predetermined period of time has elapsed since the load inlet temperature belonged to temperature level 7, the number of operating units is switched from 0 to 2 at once. In this way, it is possible not only to switch one device at a time, but also to switch a plurality of devices at once.

Similarly, when reducing the number of operating units, it is possible not only to switch one unit at a time, but also to switch a plurality of units at once, for example, from 2 to 0 for temperature level 1.

Based on these considerations, it can be said that the first table and the second table show the set value of the load inlet temperature that serves as a reference for switching the number of operating refrigerators 10. The set value of the load inlet temperature, which is a reference for switching the number of operating refrigerators 10, differs depending on the first table and the second table, that is, depending on the heat load.

Hereinafter, the set value of the load inlet temperature that serves as a reference for increasing the number of operating chillers 10 will be referred to as an increase set temperature, and the set value of the load inlet temperature that will serve as a reference for decreasing the number of operating chillers 10 will be referred to as a decrease setting. Sometimes called temperature.

In the first table, an increase set temperature and a decrease set temperature are set when the heat load is relatively high (for example, when the heat load is 1000 kW or more). Further, in the second table, an increase set temperature and a decrease set temperature are set when the heat load is relatively low (for example, when the heat load is less than 1000 kW).

There are a plurality of increased set temperatures corresponding to the combination of the number of operating units before and after switching. For example, increase set temperature as a reference for increasing the number of operating machines from 0 to 1 (0 → 1), increasing set temperature as a reference for increasing the number of operating machines from 0 to 2 (0 → 2), number of operating machines There are increasing set temperatures that serve as a reference for increasing the number of machines from one to two (1→2), and increasing set temperatures that serve as a reference for increasing the number of operating machines from two to three (2→3).

Further, the increased set temperature is set to at least the lowest temperature in the set temperature range of the load inlet temperature in which the number of operating units is increased for one combination of the number of operating units before and after switching.

For example, in the first table shown in FIG. 2(a), the increase set temperature for increasing the number of operating machines from 0 to 1 is "7°C or higher", and the increase setting for increasing the number of operating machines from 1 to 2 The set temperature is "8.5°C or higher," and the increased set temperature for increasing the number of operating units from two to three is "13.0°C or higher."

In addition, in the second table shown in Figure 2(b), the increased set temperature for increasing the number of operating machines from 0 to 1 is "9.5°C or higher", which increases the number of operating machines from 1 to 2. The increased set temperature for increasing the number of operating machines is "13.0°C or higher", and the increased set temperature for increasing the number of operating machines from 2 to 3 is "15°C or higher".

In this way, for the increase set temperature where the combination of the number of operating units before and after switching is common between the first table and the second table, the increase set temperature of the second table is relatively higher than the increase set temperature of the first table. It is set. For example, the increase set temperature for increasing the number of operating machines from 0 to 1 is "7° C. or higher" in the first table, but is "9.5° C. or higher" in the second table.

Moreover, there are multiple reduction set temperatures corresponding to the combinations of the number of operating units before and after switching. For example, the reduction setting temperature that is the standard for reducing the number of operating cars from 2 to 1 (2 → 1), the reduction setting temperature that is the reference for reducing the number of operating cars from 1 to 0 (1 → 0), the number of operating cars There is a reduction setting temperature that becomes a reference for decreasing from 2 units to 0 units (2 → 0).

Further, the reduction set temperature is set to at least the highest temperature within the set temperature range of the load inlet temperature in which the number of operating units is to be reduced for one combination of the number of operating units before and after switching.

For example, in the first table shown in Figure 2(a), the reduction setting temperature for reducing the number of operating machines from 2 to 1 is "less than 7.0°C", and the number of operating machines is reduced from 1 to 0. The set temperature for reduction is "less than 6.0°C".

In addition, in the second table shown in Figure 2(b), the reduction set temperature for reducing the number of operating machines from 2 to 1 is "less than 8.5°C", and the number of operating machines is reduced from 1 to 0. The set temperature for reduction is "less than 6.5°C".

In this way, for the reduction setting temperature where the combination of the number of operating units before and after switching is common between the first table and the second table, the reduction setting temperature of the second table is relatively higher than the reduction setting temperature of the first table. It is set. For example, the reduction setting temperature for reducing the number of operating machines from 1 to 0 is "less than 6.0°C" in the first table, but is "less than 6.5°C" in the second table.

If the acquired load inlet temperature changes to a load inlet temperature of another temperature level before a predetermined time elapses (for example, the load inlet temperature belonging to temperature level 4 changes from the load inlet temperature belonging to temperature level 5 to (e.g., when the load inlet temperature changes), maintain the current number of units in operation. This can suppress frequent changes in the number of operating vehicles. As a result, the refrigerator 10 can be started and stopped appropriately.

In addition, when the acquired load inlet temperature is maintained at the same temperature level (for example, temperature level 5, etc.) for a predetermined period of time (for example, 1 minute), the operating number control unit 84 controls the number of operating machines to be changed to a new number of operating machines. Derive. Note that if the same determination (when the refrigerators are operated in the same way) is maintained, a new number of operating units may be derived even if the temperature level is changed.

Usually, in summer, the temperature of the air introduced into the chilled water load equipment 12 is high, so the heat load on the chilled water load equipment 12 is high. When the heat load derived by the heat load derivation part 82 is 1000 kW or more, such as in summer, the operating number control unit 84 derives a new number of operating refrigerators 10 using the first table. At this time, the operating number control unit 84 refers to the first table and determines whether to maintain the current number of operating machines or increase or decrease the number of operating machines based on the acquired load inlet temperature and the current number of operating machines. .

Specifically, if the acquired load inlet temperature is equal to or higher than any increase setting temperature corresponding to the current number of operating units in the first table, the operating number control unit 84 increases the operating number of chillers 10. let For example, if the heat load is 1000 kW or more and the load inlet temperature is 9.0°C, and the current number of operating units is 2, the operating unit number control unit 84 reduces the number of operating units to 2. If the current number of machines in operation is one, the number of machines in operation is increased from one to two.

Moreover, the operating number control unit 84 reduces the number of operating refrigerators 10 if the acquired load inlet temperature is less than any reduction setting temperature corresponding to the current number of operating refrigerators in the first table. For example, if the heat load is 1000 kW or more and the load inlet temperature is 6.8°C, and the current number of operating units is 2, the operating unit number control unit 84 changes the number of operating units from 2 to 2. If the current number of machines in operation is one, the number of machines in operation is maintained at one.

Furthermore, in winter, the temperature of the air introduced into the chilled water load equipment 12 is low, so the heat load on the chilled water load equipment 12 is low. When the heat load derived by the heat load deriving unit 82 is less than 1000 kW, such as in winter, the operating number control unit 84 derives a new number of operating refrigerators 10 using the second table. At this time, the operating number control unit 84 refers to the second table and determines whether to maintain the current number of operating units or increase or decrease the number of operating units based on the acquired load inlet temperature and the current number of operating units. .

Specifically, if the acquired load inlet temperature is equal to or higher than any increase setting temperature corresponding to the current number of operating refrigerators in the second table, the operating number control unit 84 increases the number of operating refrigerators 10. let For example, when the heat load is less than 1000 kW and the load inlet temperature is "14.0°C", if the current number of operating units is 2, the operating unit number control unit 84 reduces the number of operating units to 2. If the current number of machines in operation is one, the number of machines in operation is increased from one to two.

Moreover, the operating number control unit 84 reduces the number of operating refrigerators 10 if the acquired load inlet temperature is less than any reduction setting temperature corresponding to the current number of operating refrigerators in the second table. For example, if the heat load is less than 1000 kW and the load inlet temperature is "8.0°C" and the current number of operating units is 2, the operating unit number control unit 84 changes the number of operating units from 2 to 2. If the current number of machines in operation is one, the number of machines in operation is maintained at one.

In this way, the operating unit number control unit 84 selects a table (first table or second table) according to the derived thermal load, refers to the selected table, and calculates the load obtained by the load inlet temperature sensor 30. The new number of operating units is determined from the inlet temperature and the current number of operating units.

Moreover, when the number of operating vehicles is switched, the operating number control unit 84 maintains the number of operating vehicles after switching until a predetermined time (for example, one minute) has elapsed after switching the number of operating vehicles. This also makes it possible to suppress frequent changes in the number of operating vehicles.

In addition, the first table shows the increase set temperature corresponding to the current number of operating machines (for example, the increase set temperature "8.5°C or higher" when increasing from 1 to 2 machines) and the decrease corresponding to the increased number of operating machines. The set temperature (for example, the reduction set temperature "less than 7.0°C" for reducing from two units to one unit) is set at a distant temperature. In addition, the second table similarly corresponds to the increased set temperature corresponding to the current number of operating machines (for example, the increased set temperature "13.0°C or higher" when increasing from 1 to 2 machines) and the increased number of operating machines. The reduction setting temperature (for example, the reduction setting temperature "less than 8.5° C." for reducing from two units to one unit) is set at a distant temperature. This also makes it possible to suppress frequent changes in the number of operating vehicles.

Further, the operating number control unit 84 is not limited to increasing or decreasing the number of operating vehicles one by one. For example, as shown in "15.0°C or higher" in the first table, the operating number control unit 84 may increase the number from one to three, or from zero to three, according to the current number of operating machines. May be increased. Further, for example, as shown in "less than 6.0°C" in the first table, the operating number control unit 84 may reduce the number of operating units from 2 to 0, or from 3 to 0, according to the current number of operating units. It may be reduced to a base.

FIG. 3 is a flowchart illustrating the operation flow of the thermal load deriving section 82. The thermal load deriving unit 82 repeats the series of processes shown in FIG. 3 as interrupt processing at predetermined time intervals (for example, every second).

First, the thermal load deriving unit 82 acquires the load inlet temperature from the load inlet temperature sensor 30, and acquires the load outlet temperature from the load outlet temperature sensor 32 (S100). Next, the thermal load deriving unit 82 derives the temperature difference between the load inlet temperature and the load outlet temperature (S110).

Next, the thermal load deriving unit 82 obtains the flow rate from the flow meter 26 (S120). Next, the thermal load deriving unit 82 derives the thermal load on the chilled water load equipment 12 from the derived temperature difference and the acquired flow rate (S130), and ends the series of processing.

FIG. 4 is a flowchart illustrating the operation flow of the operating number control unit 84. When activated, the operation number control unit 84 starts a series of processes shown in FIG. 4 .

First, the operating number control unit 84 performs various initial settings (S200). For example, the operating unit number control unit 84 sets the current number of operating units to 0 and temporarily sets the current temperature level of the load inlet temperature. Further, the operation number control unit 84 starts counting after resetting the first timer that counts time. Additionally, the operating number control unit 84 resets a second timer that counts time separately from the first timer.

Next, the operation number control unit 84 determines whether a termination instruction indicating termination has been obtained (S210). When the termination instruction is obtained (YES in S210), the series of processes in FIG. 4 is terminated.

If the termination instruction has not been obtained (NO in S210), the operating number control unit 84 obtains the load inlet temperature from the load inlet temperature sensor 30 and the load outlet temperature from the load outlet temperature sensor 32 (S220). Next, the operating unit number control unit 84 derives the temperature level to which the load inlet temperature belongs from the acquired load inlet temperature (S230).

Next, the operating number control unit 84 determines whether the derived temperature level is equal to the current temperature level (S240). If the temperature level is not equal to the current temperature level (NO in S240), the operating number control unit 84 maintains the current number of operating machines (S250). Then, the operation number control unit 84 resets the count of the first timer to restart counting (S260), and returns to the process of step S210. In other words, the operating unit number control unit 84 considers that the acquired load inlet temperature has changed to another temperature level before the predetermined time has elapsed, and again maintains the load inlet temperature after the change for the predetermined time. judge the progress of

Further, if the derived temperature level is equal to the current temperature level (YES in S240), the operating number control unit 84 determines whether the count of the first timer exceeds a predetermined count (S270). If the count of the first timer does not exceed the predetermined count (NO in S270), the operating number control unit 84 returns to the process of step S210. In other words, the operating unit number control unit 84 considers that the predetermined time has not yet passed since the current temperature level has been reached, and repeatedly monitors the temperature level of the load inlet temperature until the predetermined time has elapsed.

If the count of the first timer exceeds the predetermined count (YES in S270), the operating unit number control unit 84 assumes that the acquired load inlet temperature has been maintained at the same temperature level for a predetermined period of time, and calculates the heat load. The heat load derived in section 82 is acquired (S280).

Next, the operating number control unit 84 refers to a table based on the acquired thermal load, and derives a new number of operating machines based on the acquired load inlet temperature and the current number of operating machines (S290).

Next, the operating number control unit 84 determines whether the derived number of operating vehicles is equal to the current number of operating vehicles (S300). If it is equal to the current number of operating vehicles (YES in S300), the operating number control unit 84 maintains the current number of operating vehicles (S310), and returns to the process of step S210. In other words, in this case, the number of operating vehicles is not switched.

If the derived number of operating vehicles is not equal to the current number of operating vehicles (NO in S300), the operating vehicle number control unit 84 switches the operating number to the derived number of operating vehicles (S320). For example, when increasing the number of operating units from 0 to 1, the operating unit number control unit 84 starts the refrigerator 10a and transmits a frequency command value for rotating the primary cold water pump 18 to the primary inverter 62a. Next, the operating number control unit 84 stores the number of operating vehicles after switching as the current number of operating vehicles (S330).

Next, the operating number control unit 84 starts counting the second timer (S340). Next, the operating number control unit 84 determines whether the count of the second timer exceeds a predetermined count (S350). If the count of the second timer does not exceed the predetermined count (NO in S350), the operating number control unit 84 maintains the number of operating vehicles after switching (S360), and returns to the process of step S350. In other words, the operating number control unit 84 maintains the number of operating vehicles after switching, regardless of the load inlet temperature, until a predetermined time has elapsed after switching the operating number.

If the count of the second timer exceeds the predetermined count (YES in S350), the operating number control unit 84 resets the first timer to restart counting, resets the second timer (S370), and steps S210. Return to processing. In other words, the operating number control unit 84 makes it possible to switch the number of operating machines depending on the load inlet temperature.

As described above, in the refrigerator system 1 of the present embodiment, the increased set temperature when the heat load is relatively low is set relatively higher than the increased set temperature when the heat load is relatively high. ing. The operating number control unit 84 increases the number of operating refrigerators 10 when the load inlet temperature becomes equal to or higher than the increase setting temperature corresponding to the heat load.

Therefore, when the heat load is relatively low, the operating number control unit 84 waits until the load inlet temperature measured by the load inlet temperature sensor 30 becomes relatively high, and then increases the number of operating refrigerators 10. .

As a result, in the refrigerator system 1 of this embodiment, when the heat load is low such as in winter, the interval from the stop of operation of the refrigerator 10 to the start of operation becomes longer, and energy saving of the refrigerator 10 is possible. Furthermore, in the refrigerator system 1 of this embodiment, the life of the refrigerator 10 can be extended by increasing the time during which the operation of the refrigerator 10 is stopped.

Note that in winter, since the outside temperature is low, it is difficult for the pipes 16b, 16c, and 16d to warm up. As a result, the temperature of the heat medium supplied to the chilled water load equipment 12 is difficult to rise. Therefore, when the heat load is low such as in winter, even if you wait until the load inlet temperature becomes high and then increase the number of operating chillers 10, sufficient cold heat (chilled heat medium) will not be supplied to the chilled water load equipment 12. can be supplied.

Furthermore, when the heat load is relatively high, the operating number control unit 84 quickly increases the number of operating refrigerators 10 before the load inlet temperature measured by the load inlet temperature sensor 30 becomes relatively high.

As a result, in the refrigerator system 1 of the present embodiment, when the heat load is high such as in summer, the cold water load equipment 12 can reliably supply the necessary cold energy, and it is possible to suppress the shortage of cold energy. be.

Moreover, in the refrigerator system 1 of this embodiment, the reduction setting temperature when the heat load is relatively low is set relatively higher than the reduction setting temperature when the heat load is relatively high. Then, the operating number control unit 84 reduces the number of operating refrigerators 10 when the load inlet temperature becomes less than the reduction setting temperature corresponding to the heat load.

Therefore, when the heat load is relatively low, the operating number control unit 84 quickly reduces the number of operating refrigerators 10 before the load inlet temperature measured by the load inlet temperature sensor 30 becomes relatively too low. let

As a result, in the refrigerator system 1 of the present embodiment, when the heat load is low such as in winter, it is possible to save energy of the refrigerator 10 by stopping the operation of the refrigerator 10 earlier, and to extend the life of the refrigerator 10. You can also extend it.

Moreover, when the heat load is relatively high, the operating number control unit 84 waits until the load inlet temperature measured by the load inlet temperature sensor 30 becomes relatively low, and then reduces the number of operating refrigerators 10.

As a result, in the refrigerator system 1 of the present embodiment, when the heat load is high such as in summer, the cold water load equipment 12 can reliably supply the necessary cold energy, and it is possible to suppress the shortage of cold energy. be.

That is, in the refrigerator system 1 of this embodiment, the number of operating refrigerators 10 is controlled based on the heat load and the load inlet temperature, and the set value of the load inlet temperature is used as a reference for switching the number of operating refrigerators 10. varies depending on the heat load. As a result, in the refrigerator system 1 of this embodiment, even if the heat load on the chilled water load equipment 12 changes, it is possible to save energy in the refrigerator 10, and prevent the chilled water load equipment 12 from running out of necessary cold energy. It is possible to suppress it.

Therefore, according to the refrigerator system 1 of this embodiment, even if the heat load fluctuates, it is possible to efficiently supply the cooled heat medium to the chilled water load equipment 12.

Note that in the refrigerator system 1, the number of operating refrigerators 10 is switched using a plurality of tables (a first table and a second table) that differ depending on the heat load. However, the switching of the number of operating refrigerators 10 is not limited to the mode in which the table is used. For example, the operating unit number control unit 84 may derive the increased set temperature corresponding to the heat load using a relational expression in which the heat load and the increased set temperature are associated, or may derive the increased set temperature corresponding to the heat load and the decreased set temperature. The associated relational expression may be used to derive the reduced set temperature corresponding to the heat load. Then, the operating number control unit 84 may decide to switch the number of operating vehicles by calculation based on the derived increased set temperature and decreased set temperature.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these embodiments. It is clear that those skilled in the art can come up with various changes and modifications within the scope of the claims, and these naturally fall within the technical scope of the present invention. Understood.

INDUSTRIAL APPLICATION This invention can be utilized for a refrigerator system.

1 Refrigerator system 10 Refrigerator 12 Chilled water load equipment 30 Load inlet temperature sensor 82 Heat load derivation unit 84 Operating unit number control unit

Claims (4)

a refrigerator that cools the heat medium sent from the chilled water load equipment and supplies it to the chilled water load equipment;
a load inlet temperature sensor that detects a load inlet temperature that is the temperature of the heat medium sent to the chilled water load equipment;
a heat load derivation unit that derives a heat load in the chilled water load equipment;
An operating number control unit that controls the number of operating refrigerators based on the heat load and the load inlet temperature, and varies a set value of the load inlet temperature, which is a reference for switching the number of operating refrigerators, depending on the heat load. and,
Equipped with
A temperature level corresponding to a set temperature range indicating a range of the load inlet temperature set to determine the number of operating chillers is predetermined for each set temperature range according to the set value of the load inlet temperature. and
The operating number control unit is
Before the time period during which the temperature level is maintained at the current temperature level has elapsed, the load inlet temperature acquired by the load inlet temperature sensor is set at another temperature level different from the current temperature level. When the load inlet temperature belonging to the temperature level changes, maintaining the current operating number of the refrigerators,
Even if the time during which the temperature level is maintained at the current temperature level has passed the predetermined time, if the load inlet temperature acquired by the load inlet temperature sensor belongs to the current temperature level, the load inlet temperature is not acquired. Deriving a new operating number of the refrigerators based on the load inlet temperature,
If the derived number of operating units is equal to the current number of operating units, maintain the current operating number of the refrigerators,
A refrigerator system that switches the number of operating refrigerators to the derived number of operating refrigerators when the derived number of operating refrigerators is different from the current number of operating refrigerators . The operation number control unit is configured to set a reduction set temperature that is a set value of the load inlet temperature for reducing the number of operating refrigerators when the heat load is relatively low, and a reduction set temperature that is a set value of the load inlet temperature for reducing the number of operating refrigerators when the heat load is relatively low. The refrigerator system according to claim 1 , wherein the refrigerator system is set relatively higher than the reduction set temperature, and reduces the number of operating refrigerators when the load inlet temperature becomes less than the reduction setting temperature corresponding to the heat load. . a refrigerator that cools the heat medium sent from the chilled water load equipment and supplies it to the chilled water load equipment;
a load inlet temperature sensor that detects a load inlet temperature that is the temperature of the heat medium sent to the chilled water load equipment;
a heat load derivation unit that derives a heat load in the chilled water load equipment;
An operating number control unit that controls the number of operating refrigerators based on the heat load and the load inlet temperature, and varies a set value of the load inlet temperature, which is a reference for switching the number of operating refrigerators, depending on the heat load. and,
Equipped with
The operation number control unit is configured to set a reduction set temperature that is a set value of the load inlet temperature for reducing the number of operating refrigerators when the heat load is relatively low, and a reduction set temperature that is a set value of the load inlet temperature for reducing the number of operating refrigerators when the heat load is relatively low. A refrigerator system that is set relatively higher than the set reduction temperature, and reduces the number of operating refrigerators when the load inlet temperature becomes less than the set reduction temperature corresponding to the heat load. The operation number control unit is configured to set an increase set temperature, which is a set value of the load inlet temperature, for increasing the number of operating refrigerators when the heat load is relatively low, to increase the set temperature when the heat load is relatively high. Any one of claims 1 to 3, wherein the temperature is set relatively higher than the set increase temperature, and when the load inlet temperature becomes equal to or higher than the set increase temperature corresponding to the heat load, the number of operating refrigerators is increased. The refrigerator system described in Section .

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