JP5538191B2 - Cold / hot water system and pump control method for cold / hot water system - Google Patents

Description

  The present invention relates to a cold / hot water system and a pump control method for the cold / hot water system. In particular, the present invention relates to inverter control of the capacity of a cold / hot water pump in accordance with the capacity control of a heat source compressor for the purpose of improving COP.

In a building such as an office building, an air conditioner is provided as a heat load source in each room, and cold / hot water is often supplied to the air conditioner from a cool / heat source. Here, the cold / hot heat source device refers to one that generates cold water or hot water using a heat exchanger of a heat pump refrigeration cycle, and the cold / hot water refers to cold water or hot water generated by the cold / hot heat source device.
In such a cold / hot water supply system, a method has been proposed in which the air volume of the air conditioning fan and the flow rate of the circulation pump are controlled by a damper and a valve (see, for example, Patent Document 1).
Moreover, what controls the bypass amount of a heat load source and performs the number control of a heat source machine is known (for example, refer nonpatent literature 1).

JP 2000-358399 A

Air Conditioning / Hygiene Engineering Conference “Air Conditioning / Hygiene Engineering Handbook” 13th edition General-purpose equipment / Air conditioning equipment pp. 633-634

In the conventional heat source apparatus disclosed in Patent Document 1, the method of controlling the air volume of the air conditioning fan and the flow rate of the circulation pump with a damper and a valve is not suitable for reducing power consumption.
Moreover, in the conventional heat source machine shown in the said nonpatent literature 1, even when the load was small, the cold / hot water pump was drive | operated by making the cold / hot water flow volume (frequency) constant. For this reason, there was a problem that wasteful power consumption increased and the efficiency of the system was poor.

  The present invention has been made in order to solve the above-described problems, and it is possible to reduce the power consumption of the pump in accordance with the capacity reduction by the capacity control of the heat source unit, and to improve the efficiency of the entire system. It is an object to obtain a pump control method of a system and a cold / hot water system.

  The cold / hot water system according to the present invention includes a plurality of heat load sources and a heat pump refrigeration cycle including a compressor, and a plurality of cold / heat source devices for heating or cooling cold water passing through each of the heat load sources, The ratio of the frequency of the chilled / hot water pump provided corresponding to the chilled / hot heat source unit, the inverter driving the chilled / hot water pump, and the frequency of the compressor to the rated frequency of the compressor. Calculate the operating frequency of the chilled / hot water pump from the rated frequency of the chilled / hot water pump so that the ratio is approximately the same as the calculated frequency ratio, and set the inverter to operate the chilled / hot water pump based on the calculated operating frequency. And a control unit for controlling.

  According to the present invention, when the load is reduced, the frequency of the cold / hot water pump is reduced and the flow rate is reduced, so that the power consumption of the pump is reduced and the efficiency (coefficient of performance COP) of the entire system is improved.

It is a schematic block diagram which shows the cold / hot water system in Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the control part in Embodiment 1 of this invention. It is a figure which shows the relationship between the cooling capacity ratio of the heat-source equipment in the past, and COP. It is a figure which shows the relationship between the cooling capacity ratio and COP of the heat-source equipment in this invention. It is a schematic block diagram which shows the cold / hot water system in Embodiment 2 of this invention. It is a flowchart figure which shows the operation | movement of the control part in the Embodiment 2 of this invention, and a comprehensive control part.

Embodiment 1 FIG.
FIG. 1 is a schematic configuration diagram showing a cold / hot water system according to Embodiment 1 of the present invention.
As shown in FIG. 1, the cold / hot water system in this Embodiment 1 is the heat source machine 11 and 21 which heats or cools the cold / hot water which passes each of several heat load sources (not shown), such as an air conditioner. , 31 and cold / hot water pumps 12, 22, 32 that are provided corresponding to the heat source devices 11, 21, 31 and circulate and supply cold / hot water. In FIG. 1, the configuration of three units is described. However, the configuration is not limited to this, and one, two, or four or more units can be applied.
In the following, since the configuration of all three units is the same, only one unit will be described in order to simplify the description. The heat source unit 11 includes a heat pump refrigeration cycle 14 including a compressor 15 capable of capacity control, a heat exchanger 16 that heats or cools the cold / hot water by exchanging heat between the cold / hot water and the refrigerant, and the frequency of the compressor 15. The inverter 17 which can change these, and the control part 13 which controls these are provided.
The cold / hot water pump 12 is driven by a cold / hot water pump inverter 18 so as to vary the frequency, and circulates and supplies cold / hot water passing through a heat load source (not shown) to the heat source unit 11.

FIG. 2 is a flowchart showing the operation of the control unit in the first embodiment.
Next, the operation of the control unit in the first embodiment will be described with reference to FIGS.
For example, the frequency when the compressors 15, 25, and 35 in the heat source units 11, 21, and 31 are operated at a rated compressor frequency ratio of 100% is 100 Hz. When the load is half, the capacity of the heat source machine is halved, and the compressors 15, 25, and 35 are operated at 50 Hz, which is half the compressor frequency.

Hereinafter, the operations of the control units 13, 23, and 33 in the three heat source units 11, 21, and 31 are all the same. Therefore, the operation will be described by representing only one unit.
The control unit 13 in the heat source device 11 first measures the frequency of the compressor 15 (step S201). Here, the frequency of the compressor 15 can be obtained by measurement, but a frequency command created based on a temperature difference between the set temperature and the current temperature may be used. The frequency may be measured using a speed detector, or the output current and direct current of the inverter 17 are detected by a detector, and the frequency of the compressor 15 is estimated based on the outputs of these detectors. May be. Next, the control unit 13 calculates the ratio of the frequency to the rated frequency when the rated frequency of the compressor 15 is 100% (hereinafter referred to as the frequency ratio) (step S202). Here, the rated frequency ratio is 50%.

Next, the control unit 13 controls the cold / hot water pump inverter 18 to change the frequency of the cold / hot water pump 12 to operate. At this time, the new frequency for driving the cold / hot water pump 12 uses a frequency obtained by multiplying the rated frequency of the cold / hot water pump 12 by the same ratio as the frequency ratio of the compressor 15 calculated in step S202.
Since the other two units are the same as described above, description of the operation is omitted.

With this control, when the frequency ratio is 50%, the power consumption ratio with respect to the rated power consumption is about 25% when the rated power consumption of the cold / hot water pumps 12, 22, 32 is 100%.
As described above, when the load is reduced, the frequency of the cold / hot water pumps 12, 22, and 32 is reduced accordingly, and the flow rate is reduced. Thereby, the power consumption of the cold / hot water pumps 12, 22, 32 is reduced, and the efficiency of the entire system is improved.

FIG. 3 shows an example of the frequency ratio and the system COP (coefficient of performance) of the total compressor frequency of the eight heat source units with respect to the rated frequency when conventional control is performed. FIG. 4 shows an example of the frequency ratio with respect to the rated frequency and the system COP (coefficient of performance) when the total compressor frequency of the eight heat source units is 100% when this control is performed.
The conventional example shown in FIG. 3 shows a case where the power consumption of the compressor power consumption is 10% of the rated compressor power consumption when the power consumption of the compressor is 100%, and the power consumption of the cold / hot water pump is used. In this example, when the heat load is reduced and the frequency ratio is lowered, the power consumption of the cold / hot water pump is constant, so the COP (coefficient of performance) remains at a maximum of about 3.2.
On the other hand, in the present invention shown in FIG. 4, when the load decreases and the frequency ratio decreases, the power consumption ratio of the cold / hot water pump when the rated cold / hot water pump power consumption is 100% is changed by this control. The COP is 4.4, which is improved by about 38%.

Embodiment 2. FIG.
FIG. 5 is a schematic configuration diagram showing a cold / hot water system according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts. 5 is different from FIG. 1 in that an integrated control unit 19 is added. The general control unit 19 is connected to the control units 13, 23, and 33 via a local bus. In FIG. 1, the inverters 18, 28, and 38 for the cold / hot water pump are connected to the control units 13, 23, and 33, respectively. In FIG. 5, the inverters 18, 28, and 38 for the cold / hot water pump are controlled. They are not connected to the units 13, 23, 33, but are all connected to the general control unit 19 via a local bus.

FIG. 6 is a flowchart showing the operations of the control unit and the general control unit in the second embodiment.
Next, operations of the control unit and the general control unit in the second embodiment will be described with reference to FIGS. 5 and 6. In this flowchart, the control units 13, 23, and 33 are referred to as heat source machine control units in order to distinguish them from the general control unit 19.
For example, the frequency when the compressors 15, 25, and 35 in the heat source units 11, 21, and 31 are operated at a rated compressor frequency ratio of 100% is 100 Hz. When the load is half, the capacity of the heat source machine is halved, and the compressors 15, 25, and 35 are operated at 50 Hz, which is half the compressor frequency.

  In step S201, the heat source machine control units 13, 23, and 33 operate in the same manner as in step S201 in FIG. That is, the heat source machine control unit 13 measures the frequency of the compressor 15, the heat source machine control unit 23 measures the frequency of the compressor 25, and the heat source machine control unit 33 measures the frequency of the compressor 35.

  Next, in step S601, the general control unit 19 obtains the frequencies of the compressors 15, 25, and 35 from the heat source device control units 13, 23, and 33, and calculates the total frequency thereof. Since there are three in this example, 50 Hz × 3 = 150 Hz.

Next, the general control unit 19 calculates a frequency ratio with respect to the rated frequency when the sum of the rated frequencies of the three compressors is 100% (step S602). Here, the rated frequency ratio is 50%.
In this example, the sum of the rated frequencies of the three compressors is used, but it goes without saying that if the number of connected heat source units increases, the total number of units increases accordingly.

  Next, the general controller 19 operates the cold / hot water pumps 12, 22, and 32 by changing the frequency by the inverters 18, 28, and 38 for the cold / hot water pump (step S603). At this time, the new frequency for driving the chilled / hot water pumps 12, 22, 32 is obtained by multiplying the rated frequency of the chilled / hot water pumps 12, 22, 32 by approximately the same ratio as the frequency ratio of the compressor calculated in step S 602. Frequency is used.

  With the above control, when the frequency ratio is 50%, the power consumption ratio of the cold / hot water pumps 12, 22, and 32 is about 25%. In this way, when the load is reduced, the frequency of the cold / hot water pump is reduced and the flow rate is reduced. This reduces the power consumption of the pump and improves the overall system efficiency.

  11 heat source machine, 12 cold / hot water pump, 13 control unit (heat source machine control unit), 14 heat pump refrigeration cycle, 15 compressor, 16 water refrigerant heat exchanger, 17 inverter for compressor, 18 inverter for cold / hot water pump, 19 general Control part, 21 Heat source machine, 22 Cold / hot water pump, 23 Control part (heat source machine control part), 24 Heat pump refrigeration cycle, 25 Compressor, 26 Water refrigerant heat exchanger, 27 Inverter for compressor, 28 Inverter for cold / hot water pump 31 heat source machine, 32 cold / hot water pump, 33 control part (heat source machine control part), 34 heat pump refrigeration cycle, 35 compressor, 36 water refrigerant heat exchanger, 37 inverter for compressor, 38 inverter for cold / hot water pump.

Claims (4)

Multiple heat load sources;
A plurality of cold / hot heat source machines for heating or cooling cold / hot water passing through each of the heat load sources, having a heat pump refrigeration cycle including a compressor;
A cold / hot water pump provided corresponding to each cold / heat source machine;
An inverter that is provided corresponding to each cold / hot water pump, and drives the cold / hot water pump;
Calculate the frequency ratio of the compressor frequency to the compressor rated frequency, calculate the operating frequency of the cold / hot water pump from the rated frequency of the cold / hot water pump so as to be substantially the same ratio as the calculated frequency ratio, And a controller for controlling the inverter so as to operate the cold / hot water pump based on the calculated operating frequency. Multiple heat load sources;
A plurality of cold / hot heat source machines for heating or cooling cold / hot water passing through each of the heat load sources, having a heat pump refrigeration cycle including a compressor;
A cold / hot water pump provided corresponding to each cold / heat source machine;
An inverter that is provided corresponding to each cold / hot water pump, and drives the cold / hot water pump;
A control unit that is provided corresponding to each of the cold / hot heat source machines, and calculates a frequency ratio of the frequency of the compressor of the cold / hot heat source machine to the compressor rated frequency;
Calculate the total frequency of the compressors of each heat source unit individually calculated by each control unit, calculate the frequency ratio of the calculated total frequency to the total compressor rated frequency, and approximately the same ratio as the calculated frequency ratio An overall control unit that calculates the operating frequency of the cold / hot water pump from the rated frequency of the cold / hot water pump so that the inverter is operated to operate the cold / hot water pump based on the calculated operating frequency; A hot and cold water system characterized by comprising A first step in which the control unit calculates a frequency ratio of the frequency of the compressor of the cold / hot water heat source unit to the rated frequency;
A second step of calculating the operating frequency of the cold / hot water pump from the rated frequency of the cold / hot water pump so that the control unit has substantially the same ratio as the frequency ratio of the compressor calculated in the first step;
A third step of controlling the inverter for the cold / hot water pump so that the controller drives the cold / hot water pump based on the operating frequency of the cold / hot water pump calculated in the second step; A pump control method for a cold / hot water system. A first step in which the general control unit acquires the frequency of each compressor from the control units of the plurality of heat source units;
A second step in which the integrated control unit calculates the sum of the frequencies of the compressors of the cold / hot water heat source unit;
A third step of calculating a frequency ratio of the total frequency of the compressor calculated by the general control unit to a total of rated frequencies;
The total control unit calculates the frequency of the chilled / hot water pump corresponding to each heat source device from the rated frequency of the chilled / hot water pump so that the frequency ratio is substantially the same as the frequency ratio of the compressor calculated in the third step. 4 steps,
A fifth step of controlling the inverter for the cold / hot water pump so that the integrated control unit drives the cold / hot water pump based on the operating frequency of the cold / hot water pump calculated in the fourth step; A pump control method for a cold / hot water system.

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