JPH08271066A - Number-of-refrigerators controller for refrigerator - Google Patents

Abstract

PURPOSE: To prevent the excess operation of a refrigerator by composing a plurality of refrigerators of a first refrigerator group having one or more refrigerators and a second refrigerator group having the residual refrigerators and capacity-controlling the first and second groups by different references. CONSTITUTION: First to third refrigerators 14a to 14c are divided into a first refrigerator group having a first refrigerator 14a and a second refrigerator group having second and third refrigerators 14b, 14c. When the refrigerators 14a to 14c are capacity-controlled, the normal first reference value is set only in the first group, and a second reference value more severe than the first value is set in the second group. Thus, the second group is set to be scarcely started for the capacity control. As a result, the capacity control only by the first group can be realized, thereby preventing the excess operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigerator for efficiently and stably controlling the operating number of a plurality of refrigerators which are connected in parallel and each of which can individually control the capacity, according to an air conditioning load. Related to the unit number control device.

[0002]

2. Description of the Related Art Conventionally, there has been known a multi-type heat source system in which a plurality of refrigerators whose capacities can be individually controlled are arranged in parallel in order to enhance the capacity as a refrigerator. In controlling the number of operating refrigerators in such a heat source system, the load flow rate required on the load side is multiplied by the difference between the water temperature sent from the refrigerator side and the water return temperature from the load side. The number of operating refrigerators was determined according to the calculated calorific value.

However, the method of controlling the number of refrigerators as described above has the following problems. (1) Excessive operation Each connected refrigerator has a throttling mechanism, and the capacity can be controlled individually. For this reason, a larger number of refrigerators may be throttled for a load that can be sufficiently accommodated by operating a small number of refrigerators, which may result in excessive operation. For example, in the case of a system that controls the number of three refrigerators, it is a case in which three refrigerators are operated at a throttle operation of 33% for a load of one refrigerator (100%).

(2) Fluctuation of Refrigerator Capacity Further, the capacity of each refrigerator fluctuates by about 20 to 30% due to the fluctuation of the cooling water temperature, the influence of the dirt on the condenser, and the like. Therefore, in the system as described above, the heat quantity set value serving as the reference for controlling the number of units is determined based on the minimum capacity value (lower limit value of capacity fluctuation) of the refrigerator. Therefore, in the case where the capacity of the refrigerator can be sufficiently drawn out, the throttling operation may be performed by the extra number selected based on the minimum capacity value.

[0005]

SUMMARY OF THE INVENTION According to the present invention, although the refrigerator itself is controlled on the basis of the outlet temperature, the number of refrigerators is controlled on the basis of the heat quantity. It was made in view of the above problems of the device, and its purpose is to prevent excessive operation of the refrigerator and to flexibly respond to fluctuations in the capacity of each refrigerator. Therefore, it is an object of the present invention to provide a controller for controlling the number of refrigerators, which is capable of energy saving and is excellent in control stability.

[0006]

In order to solve the above-mentioned problems, according to a first aspect of the present invention, the operating number of a plurality of refrigerators connected in parallel and capable of individually controlling the capacity is requested. The refrigerator number control device that controls according to the load
A plurality of refrigerators is configured by a first refrigerator group including one or more refrigerators and a second refrigerator group including a remaining refrigerator, and the first refrigerator group and the second refrigerator. It is characterized in that the capacity of the machine group is controlled on a different basis.

In this case, the capacity of the first refrigerator group and the second refrigerator group can be controlled on the basis of the temperature set value at the outlet of each refrigerator. Further, according to the temperature setting value of each refrigerator outlet, a capacity control permission command is given only to the first refrigerator group, and a capacity control disapproval instruction is given to the second refrigerator group. It is also possible to control.

In order to solve the above problems, according to a second aspect of the present invention, the operating number of a plurality of refrigerators connected in parallel and capable of individually controlling the capacity is controlled according to a required load. The controller for controlling the number of refrigerators controls the reference value set based on the refrigerator inlet temperature in cascade according to the operating number of the refrigerators, and the operating number of the refrigerators is reduced according to the reference value. It is characterized by that.

When the reference value set on the basis of the refrigerator inlet temperature is cascade controlled according to the number of operating refrigerators, the required load is bypassed and the bypass connecting the inlet side and the outlet side of the refrigerator is bypassed. This can be achieved by providing a path and providing the bypass path with a predetermined capacity, for example, the capacity of one refrigerator.

[0010]

According to the first aspect of the present invention, since the capacities of the first refrigerator group and the second refrigerator group are controlled by different standards, for example, the first refrigerator group (base refrigerator group) is used. ) Is set to a normal reference value and the second refrigerator group is set to a stricter reference value than the normal reference value, it is possible to make it difficult for the second refrigerator group to enter the capacity control operation. . As a result, the capacity control can be realized only by the first refrigerator group, so that the excessive operation can be prevented and the fluctuation of the operation capacity can be flexibly dealt with.

According to the second aspect of the present invention, when controlling the number of operating refrigerators, a reference value determined based on the inlet temperature of the refrigerator is used. Since this reference value is cascade-controlled according to the current number of operating refrigerators, the current operating state of the refrigerator is reflected in the operating number control of refrigerators, and the control system is stabilized.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a refrigerator number control device according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a schematic device configuration of a heat source system of a primary pump system to which a number control device for a refrigerator according to the present invention can be applied. As shown, the first header 1
The first to third refrigerators 14a, 14b, 14c and the first to third pumps 16a, 16a,
16b and 16c are connected in parallel. The cold water generated by the first to third refrigerators 14a, 14b, 14c is fed to and mixed with the first header 10 by driving the first to third pumps 16a, 16b, 16c. It is sent to the air conditioning load 20 via the water supply conduit 18a.
Then, the return water that has been heat-exchanged by the air conditioning load 20 is returned to the second header 12 via the return water conduit 18b, and is again sent to the first to third refrigerators 14a, 14b, 14c for regeneration. To be done. In addition, the return flow pipe 18b has a flow rate adjusting valve 21
Is installed, and the flow rate can be adjusted according to the detection value of the indoor temperature detector 24. In addition, a flow meter 26 is also installed in the return water pipeline 18b.
The return water flow rate in 8b can be measured appropriately.

A bypass pipe 22 is provided between the first and second headers 10 and 12. A flow rate adjusting valve 28 is interposed in the bypass pipe 22, and the bypass pipe 22 is responsive to a signal from a differential pressure gauge 30 which detects a differential pressure between the first header 10 and the second header 12. It is possible to adjust the flow rate of the bypass flow that flows through.

The above system is provided with a controller 32. The controller 32 includes a temperature detector 24 and a flow meter 2
6, receiving the detection value detected by the differential pressure gauge 30, etc.,
The flow rate adjusting valves 21, 28 and the first to third pumps 16a to 1
It is possible to control the number of refrigerators, which will be described later, by controlling 6b and performing predetermined arithmetic processing.

Next, the operation of the refrigerator number control device configured as described above will be described. (1) Capacity Control by Base Table First, the capacity control operation of the first to third refrigerators 14a to 14c connected in parallel between the first header 10 and the second header 12 will be described.

According to the present invention, the first to third refrigerators 14a are
To 14c are a first refrigerator group (base stand) including the first refrigerator 14a and second and third refrigerators 14b and 14c.
And a second refrigerator group consisting of. Then, when the capacity of each refrigerator is controlled, the normal first reference value is set only for the first refrigerator group (base stand), and the second reference value is set.
The second reference value, which is stricter than the first reference value, is set for the refrigerator group. As a result, it becomes difficult for the second refrigerator group to enter the capacity control, so the capacity control is mainly performed by the base table.

As described above, according to the capacity control of the refrigerator according to the present invention, substantially only the base table performs the capacity control operation, and the refrigerators other than the base table perform 100% operation.
It is possible to prevent excessive operation.

The capacity control operation can be carried out in various modes according to the type of refrigerator to be controlled. Hereinafter, some examples of capacity control operation according to the type of refrigerator will be specifically described.

(A) Proportional capacity control When the refrigerator to be controlled has a proportional capacity control mechanism such as a large turbo refrigerator or an absorption refrigerator, the following capacity control is performed. Can be carried out. The reference value of the base stand that is the first refrigerator group is set in advance to, for example, 7 ° C.
(Refrigerator outlet temperature), and the reference values of the other second refrigerator groups are set to, for example, 6 ° C. (refrigerator outlet temperature). As a result, when the outlet temperature of the refrigerator becomes 7 ° C. or lower, first, only the base stand performs the throttle operation with priority, and the capacity is controlled so that the outlet temperature of the refrigerator exceeds 7 ° C. During this period, the second refrigerator group performs 100% operation without performing capacity control, so that excessive operation is prevented. Then, despite the throttle operation of the base table, the throttle operation of the second refrigerator group is started for the first time when the outlet temperature of the refrigerator becomes 6 ° C. or lower. In that case, if the inlet temperature of the refrigerator to be cascade-controlled becomes equal to or lower than a predetermined value as will be described later, the stage reduction process is performed, which will be described later.

(B) Multi-stage capacity control When the refrigerator to be controlled has a multi-stage capacity control mechanism like a reciprocating refrigerator, the following capacity control can be performed. For example, in the case of a reciprocating refrigerator or the like, each refrigerator controls the number of compressor stages so as to keep the outlet temperature of each refrigerator constant by a temperature detector included in the refrigerator body. However, if such a stage number control is performed in a plurality of refrigerators at the same time, control becomes inefficient, so according to the present invention, the second refrigerator group can be controlled according to the outlet temperature of the refrigerator group. On the other hand, a capacity control disapproval command is given, 100% operation is always performed, and a capacity control permission signal is given only to the first refrigerator group, which is the base table, to perform capacity control. As a result, it is possible to efficiently control the number of refrigerators according to the change in load.

Next, one embodiment of the operation of the refrigerator number control system according to the present embodiment will be described with reference to FIGS. In the following description, in the system shown in FIG. 1, the outlet temperature of the refrigerator is controlled to 7 ° C. and the inlet temperature of the refrigerator is controlled to 12 ° C.

First, when entering the control of the number of refrigerators, in step S10, the lower limit of the inlet temperature of the refrigerator is checked.
At that time, according to the present invention, the inlet temperature is subjected to a cascade calculation based on the number of operating refrigerators. That is, the control system can be stabilized by setting the lower limit check value of the inlet temperature to, for example, 9.5 + D ° C. and controlling the D value according to the number of operating refrigerators.

The D value can be set by a predetermined calculation in the controller 32 or by referring to a preset table based on various conventionally known cascade control methods. However, the details will not be described here.

Alternatively, as shown in FIG. 3, the bypass pipe 2
By using 2, it is possible to apply a cascade calculation to the inlet temperature. For example, the bypass pipe 22
By having a capacity for one refrigerator, it becomes possible to perform the following cascade control for the inlet temperature of the refrigerator when the stage of the refrigerator is reduced.

Number of operating units Refrigerator inlet temperature 2 units → 1 unit 9.5 ° C .: (12 + 7) / 2 3 units → 2 units 10.33 ° C.:(12×2+7)/3 4 units → 3 units 10.75 ° C. : (12 × 3 + 7) / 4 Therefore, the D value when the cascade operation is performed by the bypass pipe 22 shown in FIG. 3 is the following value. Number of operating units D value 2 units → 1 unit 0 ° C 3 units → 2 units 0.83 ° C 4 units → 3 units 1.25 ° C 5 units → 4 units 1.5 ° C

According to the above-described cascade calculation, in step S10, if the lower limit value of the inlet temperature of the refrigerator is 9.5 + D ° C or less, the process proceeds to step S11, and the number of operating refrigerators is reduced by one. .

On the other hand, in step S10,
If the inlet temperature of the refrigerator exceeds 9.5 + D ° C, the flow proceeds to step S12, and the load flow rates are compared. Then, the operating number of refrigerators is increased or decreased according to the characteristic curve of the number of refrigerators / load flow rate as shown in step S12. As shown in the figure, the characteristic curve of the number of refrigerators / load flow rate may have a hysteresis at the time of increasing and decreasing the stage.
It is preferable for the stability of the control system.

As a result of the comparison of the load flow rates in step S12, if it is determined that the load flow rate is below the predetermined value and the number of operating refrigerators is to be reduced, the process proceeds to step S11, and the operating number of refrigerators is one. Reduced.

On the other hand, as a result of the comparison of the load flow rates in step S12, when it is determined that the load flow rate exceeds the predetermined value and the number of operating refrigerators should be increased, the process proceeds to step S13. In step S13, the upper limit value of the water supply temperature is further checked, and if the water supply temperature is 8 ° C. or lower, it is not necessary to increase the stage, and the current number of operating machines is maintained. On the other hand, if the water temperature exceeds 8 ° C, the process proceeds to step S14, and the number of operating refrigerators is increased by one.

The number of operating refrigerators according to the present invention is controlled as described above. In the example shown in FIG.
Cascade calculation is performed only for the lower limit of the refrigerator's inlet temperature, but cascade calculation is also performed for the refrigerator's upper limit of the outlet temperature to stabilize the control system during the stage increase processing of the refrigerator. It goes without saying that it is also possible to achieve

Although FIG. 1 shows an example in which the controller for controlling the number of operating refrigerators according to the present invention is applied to a heat source system of a primary pump type, the present invention is not limited to such an embodiment. For example, as shown in FIG. 4, for a secondary pump type heat source system in which a third header 40 is further provided on the water supply side of the first header 10 and secondary pumps 42a, 42b, 42c are connected therebetween. It goes without saying that it can be applied.

[0033]

As described above, according to the first aspect of the present invention, since the capacity of the first refrigerator group and the capacity of the second refrigerator group are controlled by different standards, for example, the first refrigerator group is controlled. Only the refrigerator group (base refrigerator group) is set to the normal reference value, and the second
It is possible to make it difficult for the second refrigerator group to enter the capacity control operation by setting the refrigerator group of No. 2 to a reference value that is stricter than the normal reference value. As a result, the capacity control can be realized only by the first refrigerator group, so that the excessive operation can be prevented and the fluctuation of the operation capacity can be flexibly dealt with.

Further, according to a second aspect of the present invention, when controlling the number of operating refrigerators, a reference value determined based on the inlet temperature of the refrigerator is used. Since this reference value is cascade-controlled according to the current number of operating refrigerators, the current operating state of the refrigerator is reflected in the operating number control of refrigerators, and the control system is stabilized.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a heat source system to which a refrigerator operating number control device according to the present invention can be applied.

FIG. 2 is a flowchart showing an operation of the operating number controller for the refrigerator shown in FIG.

FIG. 3 is an explanatory diagram showing an enlarged return water section of the operating number control device for a refrigerator shown in FIG. 1.

FIG. 4 is a configuration diagram showing another embodiment of a heat source system to which the operating number control device for a refrigerator according to the present invention can be applied.

[Explanation of symbols]

 10 1st header 12 2nd header 14a, 14b, 14c Refrigerator 16a, 16b, 16c Pump 18a Water supply pipe line 18b Return water pipe line 20 Air conditioning load 22 Bypass pipe line

Claims (5)

[Claims] 1. A refrigerator number control device for controlling the operating number of a plurality of refrigerators connected in parallel and capable of individually controlling the capacity according to a required load, wherein the plurality of refrigerators are Alternatively, it is configured by a first refrigerator group including two or more refrigerators and a second refrigerator group including a residual refrigerator, and the first refrigerator group and the second refrigerator group are different from each other. An apparatus for controlling the number of refrigerators, characterized in that the capacity is controlled on a standard basis. 2. The refrigerator number control device according to claim 1, wherein the reference is a temperature set value at the outlet of each refrigerator. 3. A capacity control permission command is given only to the first refrigerator group, and capacity control is disabled to the second refrigerator group according to the temperature set value at the outlet of each refrigerator. The number control device of the refrigerator according to claim 2, wherein a permission command is given. 4. A refrigerator number control device for controlling the operating number of a plurality of refrigerators connected in parallel and capable of individually controlling the capacity according to a required load, the setting being based on the refrigerator inlet temperature. The controller for controlling the number of refrigerators is characterized in that the reference value is cascade-controlled according to the operating number of the refrigerator, and the operating number of the refrigerator is reduced according to the reference value. 5. The control of the number of refrigerating machines according to claim 4, wherein a bypass path of a predetermined capacity that connects the inlet side and the outlet side of the refrigerator is provided by bypassing the required load. apparatus.