JP2023151359A - Method for operating air-conditioning system and air-conditioning system - Google Patents

Abstract

To provide a method for operating an air-conditioning system capable of efficiently calculating an operating condition of each device on a secondary side, optimizing operation of each device based on the operating condition, and thereby saving energy, and provide an air-conditioning system.SOLUTION: A method for operating an air-conditioning system comprises: setting a plurality of dispersion values as a setting value of a secondary side water supply temperature, which is a temperature of cold water on an upstream side of an air conditioner 10; calculating power of each component of the air-conditioning system when the setting value of the secondary side water supply temperature is each dispersion value, by a system model 34 configured based on the assumption that a plurality of representative air conditioners 10' with the same performance is installed; identifying the dispersion value of the setting value of the secondary side water supply temperature in which the total power becomes small; and operates a primary side device so that the secondary side water supply temperature becomes the specified dispersion value.SELECTED DRAWING: Figure 1

Description

There is an application for exception to loss of novelty.

The present invention relates to a method for operating an air conditioning system in an energy-saving manner, and an air conditioning system to which the method is applied.

In the field of air conditioning, it goes without saying that energy conservation is one of the important issues. There are a wide variety of specific approaches to achieving energy conservation, but in recent years in particular, various technologies have been proposed to reduce the energy consumption of the entire system by optimizing the operating conditions of each device that makes up the air conditioning system. It has been implemented. For example, in Patent Document 1 listed below, the air conditioning load is calculated based on the inflow temperature, outflow temperature, and flow rate of cold water in a heat source device, and this and the operating conditions of the air conditioning (outside air intake air volume, supply air temperature, etc.) and the outside air It describes a technology for estimating a state quantity for optimally controlling air conditioning equipment from conditions and controlling the cooling tower fan, cooling water pump, chilled water pump, and compressor on the heat source equipment side to match this state quantity. . In addition, Patent Document 2 below discloses that during operation of the air conditioner, the measured values of the outside air wet bulb temperature, the amount of heat generated by the heat source unit, and the cold water outlet temperature are monitored, and based on this, the total value of energy consumption in each heat source unit is calculated. Optimization calculations are performed in real time to determine the control target values for the chilled water flow rate and chilled water outlet temperature in each heat source unit so that the control target values for the chilled water flow rate of the chilled water pump and the air volume of the cooling tower fan in each heat source unit are set to the minimum. The technique for determining the value is described.

JP2008-256258A Japanese Patent Application Publication No. 2017-101862

By the way, in the technologies described in Patent Documents 1 and 2 above, the operating conditions of each device are basically calculated only on the heat supply side (primary side), and the secondary side that consumes heat is calculated on the heat supply side (primary side). From the perspective of the heat supply side, which is the heat source, it is treated as a total load, and the operation has not been optimized by taking into account the operating conditions of the secondary side equipment that consumes heat. This is because, in general, in an air conditioning system, the configuration on the secondary side is more complex than that on the primary side. Of course, even if the configuration is complex, it is possible in principle to calculate the operating conditions on the secondary side. However, such calculations have not been realized in practice because the load is enormous compared to calculating the primary side. If it were possible to calculate the operating conditions of the system, including the secondary side, with a reasonably reasonable calculation load, and if the operating conditions of the entire system could be optimized based on this, it would be possible to save even more energy than before. can be achieved.

In view of these circumstances, the present invention provides an operating method for an air conditioning system that can efficiently calculate the operating conditions of each device on the secondary side, optimize the operation of each device based on this, and save energy. The aim is to provide an air conditioning system that applies the following.

The present invention provides a method of operating an air conditioning system that is configured to include at least a heat source device as a primary side device and a plurality of air conditioners as a secondary side device, and to circulate cold water between the heat source device and the air conditioner. Assuming that a plurality of distributed values are set as the setting value of the secondary water supply temperature, which is the temperature of the cold water on the upstream side of the air conditioner, and a plurality of representative air conditioners with the same performance are installed. Using the configured system model, the power of each component of the air conditioning system is calculated when the set value of the secondary water supply temperature is the above-mentioned variance value, and the secondary water supply temperature is set such that the total power is reduced. The present invention relates to a method of operating an air conditioning system, which is characterized in that a dispersion value of the values is specified, and equipment on the primary side is operated so that the secondary side water supply temperature becomes the specified dispersion value.

In the method of operating an air conditioning system of the present invention, a plurality of distributed values are set for the secondary load heat amount or a value related thereto so that the numerical range includes a reference value, and the secondary load heat amount or the value related thereto is Calculate the operating conditions of each component of the air conditioning system for each variance value, and if there are multiple calculation results that allow operation, the variance value of the secondary load heat amount or related values will be the standard value. From the closest operating conditions, identify the variance of the set value of the secondary water supply temperature that reduces the total power, and operate the primary side equipment so that the secondary water supply temperature becomes the specified variance value. I can do it.

In the method of operating an air conditioning system of the present invention, the value related to the secondary load heat amount for which the distributed value is set is such that at least one of the outdoor air load ratio and the indoor load ratio is distributed, and the other is left at 100%. can be handled.

In the method of operating an air conditioning system of the present invention, the value related to the secondary load heat amount for setting the dispersion value is determined by the sensible heat ratio for mixing outside air and return air and introducing it into the chilled water coil, and then Based on the sensible heat load that undergoes heat treatment to the set temperature of .

In the method of operating an air conditioning system of the present invention, the value related to the secondary load heat amount for setting the dispersion value can be obtained by calculating the secondary flow rate of cold water from the number of representative air conditioners in operation at any given time.

In the operating method of the air conditioning system of the present invention, the secondary side return chilled water is calculated from the representative air conditioner air volume calculated from the sensible heat load and the predetermined chilled water coil performance so that the secondary side water supply temperature has a specified distributed value. Using the temperature and required flow rate, the load factor of the refrigerator as the primary heat source can be calculated, and the number of operating refrigerators can be calculated by receiving a signal of the number of refrigerators actually in operation.

Further, the present invention relates to an air conditioning system characterized in that it is configured to be able to execute the above-described operating method for an air conditioning system.

According to the air conditioning system operating method and air conditioning system of the present invention, the operating conditions of each device on the secondary side are efficiently calculated, the operation of each device is optimized based on this, and the excellent effect of saving energy is achieved. can be played.

1 is a block diagram showing an example of a system configuration of an air conditioning system to which the present invention is applied. FIG. 2 is a block diagram conceptually illustrating the concept of secondary side operating conditions in the air conditioning system operating method according to the present invention. 1 is a block diagram showing an example of the configuration of a system model in an air conditioning system to which the present invention is applied; FIG. It is a flowchart which shows an example of the calculation procedure in the operating method of the air conditioning system by implementation of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example of the system configuration of an air conditioning system to which the present invention is applied. A plurality of refrigerators 1 are installed as heat source devices on the primary side (heat supply side) of the system, and a plurality of cooling towers 2 are connected to each refrigerator 1 via cooling water circulation paths 3, respectively. A cooling water pump 4 is installed in the middle of the cooling water circulation path 3, and when the cooling water pump 4 operates, cooling water is circulated between the refrigerator 1 and the cooling tower 2. The cooling water pump 4 is equipped with an inverter-controlled motor, and the rotation speed can be changed as necessary to adjust the flow rate of the cooling water. The same applies to 22).

Each of the refrigerators 1 is further connected to a primary cold water flow path 5, and each refrigerator 1 generates a primary cold water flow by using the cold heat of the high temperature field due to heat exchange with the atmosphere of the cooling water flowing through the cooling water circulation path 3. The cold water flowing through the passage 5 is cooled by a phase change of the refrigerant in a vapor compression refrigeration cycle, and by absorption of low-pressure vapor of water, which is a refrigerant, into an absorption liquid in an absorption refrigeration cycle. A plurality of primary cold water channels 5 extend from the primary return header 6 to the primary outgoing header 7, and a refrigerator 1 is installed in each of them. Inverter-controlled primary cold water pumps 8 are installed at positions on the upstream side of the refrigerator 1 in the primary cold water flow path 5, and when the primary cold water pumps 8 operate, the water passes from the primary return header 6 through the refrigerator 1 to the primary cold water. The flow of cold water to the outgoing header 7 is driven. In addition, the primary return header 6 and the primary outgoing header 7 are connected by a bypass flow path 9, and the flow rate of cold water on the primary side (primary cold water flow path 5) and the secondary side (secondary cold water flow path 16) described later are connected. When the flow rates of cold water differ between the two, the cold water is made to flow between the primary return header 6 and the primary outgoing header 7 to adjust the differential pressure between the headers.

A plurality of air conditioners 10 that supply conditioned air to the target space S are installed on the secondary side (heat consumption side) of the system. Each air conditioner 10 has a cold water coil 10a through which cold water circulates and exchanges heat with the air passing through the surface, and a cold water coil 10a that exchanges heat with the cold water and receives the cold heat. The air supply fan 10b is equipped with an inverter-controlled air supply fan 10b. The air outlet side of the air conditioner 10 is connected to an air supply port 12 of the target space S via an air supply duct 11, and conditioned air is supplied to the target space S from here. A damper 13 is provided at a position in front of the air supply port 12 in the air supply duct 11, and by changing the opening degree of the damper 13, the amount of conditioned air blown out from the air supply port 12 can be adjusted as appropriate. It has become.

Further, a return air port 14 for taking in indoor air is provided at an appropriate position in the target space S, and the return air port 14 is connected to the air inlet side of the air conditioner 10 via a return air duct 15. ing. An inverter-controlled return air fan 15a is provided in the middle of the return air duct 15, and when the return air fan 15a operates, a portion of the indoor air in the target space S is taken in as return air from the return air port 14. The air is then returned to the air conditioner 10 through a return air duct 15. The return air returned to the air conditioner 10 has its temperature adjusted again by the air conditioner 10, and is sent out as supply air. As will be described later, the air conditioner 10 introduces outside air into the return air duct 15, and after the point where it meets an outside air duct (not shown), the air conditioner 10 enters the air conditioner 10 as mixed return air, for example, with an air volume of 20% of the supply air. It is also possible to fix the OA ratio, which is the outside air supply ratio, where the outside air is mixed with the return air.

A secondary cold water flow path 16 is connected to the cold water coil 10a in the air conditioner 10, and cold water is supplied into the cold water coil 10a through the secondary cold water flow path 16. The secondary cold water flow path 16 extends from the secondary outgoing header 17 and is connected to the inlet side of the chilled water coil 10a, and also extends from the outlet side of the chilled water coil 10a and is connected to the secondary return header 18. The secondary return header 17 is connected to the primary return header 7 via a plurality of communication passages 20, and the secondary return header 18 is connected to the primary return header 6 via communication passages 19. Among the plural communication paths 20 connecting the primary outgoing header 7 and the secondary outgoing header 17, a minimum flow valve 21 is provided in the middle of one of the communication paths 20, and an inverter control valve is provided in the middle of the remaining communication paths 20. A secondary cold water pump 22 of the type is provided. The secondary cold water pump 22 sends cold water from the primary header 7 to the secondary header 17, and drives the flow of cold water from the secondary header 17 through the cold water coil 10a of the air conditioner 10 to the secondary return header 18. . Note that the minimum flow valve 21 is opened as appropriate when the required amount of cold water supply from the primary header 7 to the secondary header 18 is small, and even if the secondary cold water pump 22 does not operate at less than the minimum flow rate, the Adjustments are made so that the required flow rate from the outgoing header 7 to the secondary outgoing header 18 is achieved. Further, a flow rate adjustment valve 23 is installed at a position downstream of the cold water coil 10a in the secondary cold water flow path 16, and the amount of cold water flowing through the secondary cold water flow path 16 is controlled by the opening degree of the flow rate adjustment valve 23. It is being adjusted.

In this way, in the air conditioning system shown in FIG. While circulating cold water by the functions of the primary cold water pump 8 and the secondary cold water pump 22, on the primary side, the cooling water is circulated between the refrigerator 1 and the cooling tower 2 to cool the cold water in the refrigerator 1, and the On the side, air is circulated between the air conditioner 10 and the target space S to cool the air and supply it to the target space S.

In addition, temperature sensors that measure the temperature of cooling water, cold water, and air, and flow meters that measure the flow rates of these are installed at various locations in the air conditioning system. This is carried out with reference to similar measured values as appropriate. In the case of the example shown here, temperature sensors 24 for measuring the temperature of the cooling water are provided at positions on the inlet side and the outlet side of each cooling tower 2 in the cooling water circulation path 3, respectively, and each chiller in the primary cold water flow path 5 A temperature sensor 25 for measuring the temperature of the cold water is provided at a position on the outlet side of the cold water. Furthermore, temperature sensors 25 are provided in the secondary outgoing header 17 and in the communication path 19 between the secondary return header 18 and the primary return header 6 to measure the temperature of the cold water. Further, a temperature sensor 26 is provided at a position upstream of the damper 13 in the air supply duct 11 to measure the temperature of the air supply.

An outside air duct (not shown) for taking in outside air is connected in the middle of the return air duct 15, and an outside air sensor 35 for measuring outside air conditions is provided here. The outside air sensor 35 is, for example, a thermohygrometer, and measures outside air conditions such as temperature and humidity.

In addition, a flow meter 27 is provided at a position on the upstream side of each refrigerator 1 in the primary cold water flow path 5 and in the middle of the communication path 19 between the secondary return header 18 and the primary return header 6. It is adapted to measure the flow rate of cold water at a location.

Each device and each sensor are appropriately connected in terms of information by a communication network 28. Information devices such as a data collection server 29, a gateway machine 30, and a central monitoring device 31 are connected to the communication network 28, for example.

The data collection server 29 is a part that collects various data related to the operation of the air conditioning system, such as the operating status of each device and the measured values of each sensor. Various values related to the operating status are input here from the controllers (not shown) of each device such as the cold water pump 8, the secondary cold water pump 22, the minimum flow valve 21, and the flow rate adjustment valve 23, as well as temperature sensors 24 and 25. , 26, the flow meter 27, and the measured values of the outside air sensor 35 are also input and stored.

The central monitoring device 31 is a device that monitors and controls the operation of the entire air conditioning system, and appropriately refers to data input from the controllers of each device and each sensor, and data stored in the data collection server 29. Commands related to operation are input to each device.

Gateway device 30 connects communication network 28 to an external network (eg, the Internet) 32. An optimization calculation section 33, which is an information processing device such as a personal computer, is connected to the Internet 32. This optimization calculation unit 33 has a built-in system model 34 that is an information model of the entire air conditioning system, and uses the method described below based on various conditions acquired from the data collection server 29 and the central monitoring device 31 through the external network 32. Calculate the operating conditions of each part of the system and set the secondary side water supply temperature (the temperature of the cold water upstream of the air conditioner 10 in the secondary cold water flow path 16) so that the total power consumed by each device is reduced. Identify the value. The central monitoring device 31 controls each device in real time so that the secondary side water supply temperature reaches that value.

The controller (not shown) for the heat source, mainly the refrigerator 1, receives command signals input from the central monitoring device 31 via the network and the cooling water in the piping connected to the condenser, evaporator, etc. of the refrigerator 1. Based on information such as the flow rate and temperature of cold water, the rotation speed of the cooling water pump 4 and the primary cold water pump 8, the rotation speed of the compressor in the refrigerator 1, and the opening degree of the vanes are controlled via the refrigerator side panel. control. In addition, the controller (not shown) of each cooling tower 2 receives information such as command signals input from the central monitoring device 31, the temperature and humidity of the outside air, and the measured values of the temperature sensor 24 provided in the cooling water circulation path 3. Based on this, the rotation speed of the motor of the cooling tower fan provided in the cooling tower 2 is controlled.

The controller (not shown) of the air conditioner 10 receives a command signal input from the central monitoring device 31, a set temperature input to the operation panel in the target space S, a temperature sensor 26 provided in the air supply duct 11, etc. Based on the information, the opening degree of the flow rate adjustment valve 23 and the rotational speed of the air supply fan 10b and the return air fan 15a are controlled. In addition, the controller (not shown) of the secondary cold water pump 22 receives information such as command signals input from the central monitoring device 31 and measured values of the temperature sensor 25 and flow meter 27 provided in each part of the cold water flow path. Based on this, the number of operating secondary cold water pumps 22, the rotational speed of each, and the opening degree of the minimum flow valve 21 are controlled.

In addition, the number and installation position of each device such as the heat source machine (freezer) 1, the cooling tower 2, the air conditioner 10, the secondary cold water pump 22 of the primary cold water pump 8, the number of installed cooling towers 2 per refrigerator 1, The number of installed air conditioners 10 and dampers 13 for the target space S, the number and installation positions of sensors such as temperature sensors 24, 25, 26 and flow meters 27, cooling water circulation path 3, primary cold water flow path 5, and secondary cold water flow Regarding the configurations of the air passage 16, the supply air duct 11, the return air duct 15, etc., a simplified example is shown here, but the configuration shown here is just an example, and the drawing is a schematic diagram. The specific number and configuration of these devices, sensors, piping, etc. can be changed as appropriate from the configuration shown here, depending on the form of the actual air conditioning system. The same applies to the configurations of parts related to control and information management, such as the data collection server 29, central monitoring device 31, optimization calculation unit 33, and system model 34. In addition, illustrations of parts that are not directly related to the gist of the present invention or parts that do not seem particularly necessary to be shown are omitted here (for example, the above-mentioned outside air duct and the parts that harmonize the outside air taken in). external air conditioner, as well as sensors, on-off valves, flow rate adjustment valves, etc. installed in various parts not shown here).

In the air conditioning system of this embodiment, the optimization calculation unit 33 calculates the operating conditions of each device including the secondary side, and based on this calculates the secondary side water supply temperature that will save as much energy as possible for the entire system. The system is designed to operate according to the secondary water supply temperature. The concept and calculation procedure related to such optimization will be explained below. In addition, when referring to "equipment" and "component equipment" in this specification, the heat source machine (refrigerator) 1, the cooling tower 2, the cooling water pump 4, the air conditioner 10, the damper 13, the return air port 15a, the minimum flow valve 21 , secondary cold water pump 22, temperature sensors 24, 25, 26, flow meter 27, outside air sensor 35, data collection server 29, and other equipment that constitutes the air conditioning system not listed here (or not shown). refers to at least part of it. In particular, when we say "operate equipment (system components) based on the set value of the secondary water supply temperature," the equipment to be operated is at least one of the heat source equipment (refrigeration machine) 1 and the cooling tower 2. It also includes other equipment as necessary.

In this example, a simplified model (system model 34) is used for the secondary side, where the actual configuration tends to be particularly complicated and the calculation load tends to be enormous when calculating operating conditions. By doing so, we are able to optimize the entire system while also taking into account the operating conditions on the secondary side, while keeping the amount of calculations to a practical level.

In an actual air conditioning system, when a plurality of air conditioners 10 (see FIG. 1) are installed, their types and performances often differ depending on the size of the target space S in charge and the heat load situation. Furthermore, the configuration of piping and ducts (secondary cold water flow path 16, supply air duct 11, and return air duct 15) and the thermal situation of the target space S also differ depending on the location. When attempting to accurately simulate the operating conditions of each device on the secondary side, including the air conditioner 10, it is necessary to individually set and calculate these complicated situations for each air conditioner 10, which increases the calculation load. becomes enormous.

Therefore, in this embodiment, as conceptually shown in FIG. 2, each of the plurality of air conditioners 10 provided on the secondary side is replaced with a virtual representative air conditioner 10' having the same performance. Reference) is being constructed. The hypothetically used representative air conditioner 10' is, for example, selected from among the air conditioners 10 actually installed in the air conditioning system and set as an air conditioner with the same performance as that air conditioner 10. Alternatively, for example, the average value of each performance value of the plurality of air conditioners 10 installed in the air conditioning system may be calculated, and the air conditioner may be set as having the performance of the average value. It is assumed that the same number of representative air conditioners 10' (N units) are installed instead of the air conditioners 10 that are actually installed. By configuring the system model 34 based on such a hypothetical, there is no need to perform calculations for each air conditioner 10 with different performance when calculating the operating conditions of the secondary side system, and the calculation load can be significantly reduced. This is possible. It should be noted that each part other than the air conditioner 10 may be appropriately omitted, averaged, approximated, or otherwise processed. For example, regarding the target space S, it may be assumed that a plurality of representative spaces S' having the same load heat amount, volume, set temperature, etc. exist. Further, the representative air conditioner and representative space are not limited to one type for each system model, and representative air conditioners and representative spaces with a plurality of performances and specifications may be virtualized. For example, when 10 air conditioners are installed, one type of representative air conditioner is assumed for the five units with similar performance, and another type of representative air conditioner is assumed for the remaining five units. may be adopted.

Using the system model 34 created under these settings, the operating status of the primary heat source machine (refrigerator) 1, the operating status of the secondary air conditioner 10, the outside air conditions, and the load heat amount on the secondary side are Based on this, the operating conditions for each part of the air conditioning system are calculated. Using the operating conditions of the refrigerator 1 and the air conditioner 10, the outside air condition, and the secondary load heat amount as given conditions, the operating conditions of each device that can realize an appropriate air conditioning state in the target space S are calculated. Then, the energy consumption of each device under the operating conditions is calculated, and the energy consumption of the entire air conditioning system is calculated by summing them up.

This calculation is performed using the temperature of the cold water sent out from the secondary header 17 (that is, the temperature of the cold water on the upstream side of the air conditioner 10, hereinafter referred to as "secondary side water supply temperature"), and Set the side water supply temperature and perform this for each secondary side water supply temperature. In other words, for example, calculate the operating conditions for each of the five cases where the secondary water supply temperature setting value is 7°C, 8°C, 9°C, 10°C, and 11°C, and calculate the energy consumption of the entire system under those conditions. (The multiple values set for calculation in this way are hereinafter referred to as "dispersion values" for convenience). Then, from the calculated operating conditions, we identify the variance value that has the lowest energy consumption in the entire system, and then check each device that makes up the system, especially the primary side, so that the secondary side water supply temperature reaches the specified variance value. The refrigerator 1 and cooling tower 2 are operated.

Generally, the energy consumption in the refrigerator 1 and the cooling tower 2 decreases as the secondary side water supply temperature increases (that is, as the target temperature value of the cold water to be cooled increases). Since the evaporation temperature in the evaporator of the refrigerator increases, the temperature difference between the evaporator and the condenser in a vapor compression refrigerator becomes smaller, and the work of the compressor can be reduced. On the other hand, if the secondary side water supply temperature is increased, the cold water coil in the secondary side air conditioner will not be able to maintain the temperature difference between the cold water going back and forth when cooling the other air, and when conveying the same amount of heat, the secondary side The amount of circulating cold water necessary to cover the heat load increases, and the energy consumption of devices such as the primary cold water pump 8 and the secondary cold water pump 22 increases. That is, setting the secondary water supply temperature too high or too low may lead to an increase in energy consumption. Therefore, we search for the secondary water supply temperature that minimizes the total energy consumption, and then operate the air conditioning system to reach the specified secondary water supply temperature.

FIG. 3 is a block diagram illustrating the configuration of the system model 34 and the calculation procedure thereof. The system model 34 includes calculation modules corresponding to each device so as to calculate operating conditions for each device constituting the air conditioning system.

The system model 34 includes a secondary side calculation section 34a that calculates the operating conditions of each device on the secondary side, and a primary side calculation section 34b that calculates the operating conditions of each device on the primary side. The secondary side calculation unit 34a includes, as calculation modules, a room model 34c that calculates the thermal situation in each target space S, an air volume calculation unit 34d that calculates the supply air volume in each air conditioner 10, and an upstream side of the chilled water coil 10a. and a coil inlet air calculation unit 34e and a coil outlet air calculation unit 34f that calculate the state of the air on the downstream side, respectively, and a coil chilled water calculation unit that calculates the flow rate of chilled water in the chilled water coil 10a and the temperature of chilled water at the outlet of the chilled water coil 10a. 34g, a piping model 34h that calculates the amount of cold water flowing to the secondary side, and a secondary pump model 34i that calculates the operating conditions of the secondary cold water pump 22. Here, each module is configured to perform calculations for each part constituting the air conditioning system, but modules related to the air conditioner 10 (air volume calculation unit 34d, coil inlet air calculation unit 34e, coil outlet air calculation unit 34e, The air calculation unit 34f and the coil chilled water calculation unit 34g) assume the performance of the same representative air conditioner 10' and perform calculations for N units based on this (that is, multiply the calculation result by the representative air conditioner 10' by N times). do). In addition, when similarly imagining the representative space S' for the target space S, the room model 34c with the same load heat amount, volume, set temperature, etc. is also imagined, and calculations for N rooms are thereby performed. I do.

The primary side calculation unit 34b includes, as calculation modules, a heat source number control unit 34j that selects the number of operating refrigerators 1 that are heat source devices, and a heat source calculation unit 34k that calculates the operating conditions of each refrigerator 1 and each cooling tower 2. and a cooling tower calculation unit 34l. The heat source calculation unit 34k and the cooling tower calculation unit 34l perform calculations for each refrigerator 1 and cooling tower 2 provided in the air conditioning system.

The system model 34 as described above is
・Load heat amount (sensible heat load and latent heat load) in the secondary side room (target space S)
・Set temperature and humidity in the target space S (room dry bulb temperature setting, room relative humidity setting)
・Outside air temperature and humidity (outside air dry bulb temperature, outside air relative humidity)
- Set temperature and humidity of supply air (supply air temperature set value, supply air humidity set value)
・Exhaust air volume setting (exhaust air volume setting value)
・Operating status of heat source equipment (number of operating refrigerators 1 and power of each equipment)
・Operating status of air conditioners (number of operating air conditioners 10)
・With the set value of the secondary water supply temperature as a given condition, the values related to the operating conditions of each part (load, energy consumption, etc.) are calculated using the above calculation modules corresponding to each part of the air conditioning system. It calculates the power consumption of the entire system. Here, among the above given conditions, the room dry bulb temperature set value and the room relative humidity set value are values set in the target space S. As the outside air dry bulb temperature and outside air relative humidity, the measured values of the outside air sensor 35 are used. The supply air temperature set value, the supply air humidity set value, and the exhaust air volume set value are, in principle, fixed values (they can also be changed manually) and can be obtained from the central monitoring device 31. The operating status of the heat source equipment and the operating status of the air conditioner can also be acquired from the central monitoring device 31. Regarding the secondary water supply temperature, as described above, an appropriate value of, for example, 7° C. to 11° C. is set and used for calculation. The latent heat load and sensible heat load on the secondary side will be described later.

In the system model 34, first, the air volume calculation unit 34d calculates the value (m ³ /h) of the supply air volume V _S in the air conditioner 10 using the following formula.
V _S =3,600ν・Q _S /(1.006+1.805X _S )・(T _R sp - T _S )

However, ν: Air specific volume ( ^m3 /kgDA), _QS : Sensible heat load (kW), _XS : Supply air absolute humidity (kg/kgDA), _TRSp : Room dry bulb temperature setting value (℃) , T _S : supply air temperature setting value (° C.), 1.006: constant pressure specific heat of air (kJ/kg·K), 1.805: constant pressure specific heat of water vapor (kJ/kg·K).

In the room model 34c, the temperature and humidity of the indoor air and the return air volume are calculated using the value of the supply air volume _VS. The temperature of indoor air (indoor temperature T _R (℃)), the absolute humidity of indoor air (indoor absolute humidity X _R (kg/kgDA)), and the return air volume V _R (m ³ /h) are calculated using the following formulas. It can be calculated.
T _R =T _S +3,600ν・Q _S /(1.006+1.805X _S )・V _S
X _R =X _S +3,600ν・Q _L /(2,501+1.805T _R )・V _S
V _R = V _S - V _E

However, Q _L : latent heat load (kW), V _R : return air flow rate (m ³ /h), V _E : exhaust air flow setting value (m ³ /h).

The indoor sensible heat load _QS and latent heat load _QL can be determined by the following procedure. First, the load heat amount in the air conditioner 10 is determined as the product of the temperature difference of the cold water and the flow rate between the upstream side and the downstream side of the cold water coil 10a. The load heat amount thus obtained is the sum of the indoor load and the outside air load.

The air to be air-conditioned is a mixture of indoor air taken in as return air and outside air. , the operating status of the outside air conditioner (not shown), the opening degree of the damper 13, etc., and is, for example, 20% of the air introduced into the air conditioner 10. The outside air load per volume is calculated from the difference between the outside air condition (outside air dry bulb temperature, outside air relative humidity) measured by the outside air sensor 35 and the supply air condition (supply air temperature setting value, supply air humidity setting value). can. The indoor load can be calculated by subtracting the outdoor air load thus obtained from the load heat amount obtained based on the product of the temperature difference and the flow rate of the cold water in the cold water coil 10a.

The indoor load is further divided into a sensible heat load and a latent heat load, and it is assumed that the sensible heat ratio (the ratio of the sensible heat load to the indoor load) SHF is, for example, 70%. Although this ratio value is just an assumption and is not necessarily a strictly accurate value, it is possible to obtain the values of the sensible heat load Q _S and the latent heat load Q _L , respectively.

Based on the supply air volume V _S and the return air volume _VR determined above, the motive power of the supply air fan 10b and the return air fan 15a can be determined. As a calculation formula, for example, the following approximate formula, which is a quadratic approximation of the PQ diagram of the fan, can be used.
P=a・Q ² +b・Q(n/N)+c・(n/N) ² ...(1)
Pw=(ρ・g・Q・P/60,000)×η

However, a, b, c: coefficients calculated from the P-Q diagram, P: pressure (Pa), Q: flow rate (m ³ /min), n: rotation speed, N: rated rotation speed, ρ: fluid density (1.2 kg/m ³ ), g: gravitational acceleration (9.8 m/s ² ), η: efficiency, and Pw: power (kW). The flow rate Q in this equation is a value different from the above-mentioned sensible heat load _QS and latent heat load _QL , and by substituting the supply air volume V _S and return air volume V _R here, The power Pw of the fan 16a is determined.

The coil inlet air calculation unit 34e calculates outside air conditions (outside air dry bulb temperature and outside air relative humidity), return air volume V _R and state (which can be understood as indoor temperature _TR and indoor absolute humidity X _R ), supply air volume V A mixing point is calculated from _S and the state (supply air temperature setting value and supply air humidity setting value), and the temperature and absolute humidity of the air on the upstream side of the chilled water coil 10a are calculated.

The coil outlet air calculation unit 34f calculates the temperature and absolute humidity of the air on the downstream side of the chilled water coil 10a from the air volume _VS and the state (supply air temperature setting value and supply air humidity setting value).

The coil chilled water calculation unit 34g calculates the temperature of the coil based on the upstream air conditions (temperature and humidity) determined by the coil inlet air calculation unit 34e and the downstream air conditions (temperature and humidity) determined by the coil outlet air calculation unit 34f. Using the number of rows (known value), the flow rate of cold water flowing through the cold water coil 10a and the temperature of the cold water on the outlet side of the cold water coil 10a are determined. The amount of heat exchanged between cold water and air can be determined from the difference between the air conditions on the upstream and downstream sides. The specific calculation procedure is, for example, as follows. First, the amount of exchanged heat qt (W) can be determined as follows, assuming that it is the same as the heat balance on the air side.
qt=V _S ×1.2×(hc _ai・hc _ao )

However, hc _ai is the enthalpy of air at the coil inlet side (J/kg), and hc _ao is the enthalpy of air at the coil outlet side (J/kg). On the other hand, the amount of heat exchanged qt can also be expressed by the following formula.
qt=Row×Kf×dtlm×Af×WSF

However, Row: number of coil rows, Kf: heat transfer coefficient (W/m ²・℃・Row), dtlm: logarithmic average temperature difference (℃), Af: coil front area (m ² ), WSF: wetted surface coefficient. be.

The heat transfer coefficient Kf, the logarithmic average temperature difference dtlm, and the wetted surface coefficient WSF can be expressed as follows.
WSF=C ₁ ×SHF ² +C ₂ ×SHF+C ₃
Kf=C4/{1/( _C5 +uf ^C6 + _C7 )+1/( _C8 +vw ^C9 + _C10 )}
dtlm= _dt1・_dt2 /ln( _dt1 / _dt2 )
dt ₁ = tc _ai・tc _wo
dt ₂ = tc _ao・tc _wi

However, SHF is the above-mentioned sensible heat ratio, C ₁ to C ₁₀ are coefficients provided by the manufacturer, uf: Wind speed of supply air in front of the coil (m/s), vw: Flow velocity of cold water passing through the coil (m/s) ), tc _ai : Air temperature on the upstream side of the coil (°C), tc _wo : Water temperature at the outlet of the coil (°C), tc _ao : Air temperature on the downstream side of the coil (°C), tc _wi : Water temperature at the inlet of the coil (°C). be. The front wind speed uf can be determined from the supply air volume _VS , and the passing wind speed vw can be calculated from the specifications of the coil based on the front wind speed uf. The air temperatures tc _ai , tc _ao on the upstream and downstream sides of the coil, and the cold water temperature tc _wi on the inlet side of the coil are known values, and the outlet water temperature tc _wo of the coil is unknown.

The temperature tc _wo of the cold water on the outlet side of the cold water coil 10a can be calculated by the above formula, and the flow rate Q (L/min) of water in the cold water coil 10a can be determined by the following formula.
Q=60×qt/{Cw×(tc _wi −tc _wo )}

However, Cw is the mass specific heat of water (kJ/kg·°C). Note that the water flow rate Q in this equation is a value different from the above-mentioned sensible heat load Q _S and latent heat load Q _L and the fan flow rate (air volume) Q in the above-mentioned equation.

In the piping model 34h, the total flow rate of cold water on the secondary side is calculated by multiplying the flow rate of cold water per one air conditioner 10 obtained in this way by the number of operating air conditioners 10 obtained from the central monitoring device 31.

The secondary pump model 34i and the heat source number control unit 34j calculate the number of operating heat source machines (refrigerators) 1 from the total flow rate of cold water on the secondary side, and calculate the return temperature of the cold water on the secondary side (same as the coil outlet water temperature). ), and the power of the secondary cold water pump 22 and the primary cold water pump 8 is calculated based on the set value of the secondary side water supply temperature.

Specifically, first, from the total flow rate of cold water on the secondary side obtained using the piping model 34h, the minimum flow rate of each heat source device 1 is considered, and the flow rate between the primary header (primary outbound header 7 and primary return header 6) is calculated. The flow rate in the bypass channel 9 is calculated. Furthermore, the temperature of the cold water in each of the primary and secondary headers is calculated from the return temperature of the cold water on the secondary side and the set value of the secondary side water supply temperature. The load heat amount determined from the temperature and flow rate of the cold water is distributed to the rated capacity ratio of each heat source device 1, and the number of operating heat source devices 1 is determined. The number of operating secondary cold water pumps 22 is determined from the flow rate of cold water on the secondary side, and based on the water flow balance, the primary side return water temperature (chilled water temperature in the primary return header 6) and the secondary side water supply temperature (the above set value instead of the result value). Based on this, the motive power of the secondary cold water pump 22 and the primary cold water pump 8 can be calculated using a formula similar to the above formula (1).

The heat source calculation unit 34k and the cooling tower calculation unit 34l calculate the power of the heat source device 1, the fan of the cooling tower 2, and the cooling water pump 4. As an example, a calculation procedure when the heat source device 1 is a centrifugal refrigerator will be explained.

The power consumption amount E _ref in the heat source device 1 is the product of the power consumption rate e _ref and the rated power consumption amount E _{ref_r} , as shown in the following equation.
E _ref = e _ref × E _{ref_r}

The power consumption rate e _ref is determined by the following equation: a partial load factor influence coefficient C1 which is a function of the load factor q, a cooling water temperature influence coefficient C2 which is a function of the cooling water inlet temperature T _d , and a function of the cooling water flow rate ratio v _d . It can be expressed as the product of the cooling water flow rate influence coefficient C3 which is a function of the cold water flow rate ratio vc, the cooling water outlet temperature influence coefficient C4 which is a function of the cold water outlet temperature _Tc , and the cold water flow rate influence coefficient C5 which is a parameter of the cold water flow rate ratio _vc . Under rated conditions, each value of C1 to C5 is 1.0, and e _ref =1.0.
e _ref = C1 x C2 x C3 x C4 x C5
C1=a ₁ q ² +b ₁ q+c ₁
C2=a ₂ T _d ² +b ₂ T _d +c _{2
C3 = a3vd3 + b3vd2 +} ^c3vd ₊ ^d3
_C4 ⁼ _a4Tc2 + _{b4Tc + c4
C5} ⁼ _a5vc2 + _{b5vc + c5}

Here, the cold water outlet temperature _Tc is the temperature of the cold water at the outlet of the refrigerator 1, and if the distribution of cold water in the bypass flow path 9 is not considered, the resultant value of the secondary side water supply temperature obtained above can be used. I can do it. In addition, the cooling water inlet temperature T _d is the temperature of the cooling water at the inlet of the refrigerator 1, and when the bypass of the cooling water circulation path 3 is not considered, the temperature of the cooling water at the outlet of the cooling tower 2 (cooling tower outlet temperature) can be regarded as the same value.

Using the above power consumption amount E _ref , the cooling water outlet temperature (temperature of the cooling water at the outlet of the refrigerator 1) T _dr can be determined by the following equation.
q _cd = q _c +E _ref = q _c (1+1/ _{COP_qc} )
V _d = q _cd / (T _dr - T _d )

However, q _c : calorie of cold water, _{COP_qc} : coefficient of performance for each operating load factor, q _cd : calorie of cooling water, V _d : flow rate of cooling water.

On the other hand, on the cooling tower 2 side, the function T _ds of the outside air wet bulb temperature WB, the cooling tower inlet temperature influence coefficient C7 which is a function of the cooling tower inlet temperature (cooling water temperature at the inlet of the cooling tower 2) T _dr , and the cooling water Using the first cooling water amount influencing coefficient C8 and the cooling water amount influencing second coefficient C9, which are functions of the flow rate V _d , the cooling tower outlet temperature T _d can be determined as follows.
T _d = T _ds × C7 × C8 × C9
T _ds =a ₆ WB ² +b ₆ WB+c _6
C7 ⁼ _{a7Tdr2 + b7Tdr} + _c7
C8=f(C9, T _dr , WB)
_{C9 = a9Vd2} + _{b9Vd +} ^c9

Each coefficient a ₁ to a ₅ , b ₁ to b ₅ , c ₁ to c ₅ and d ₃ is calculated from a diagram provided by the manufacturer. Furthermore, the coefficients a ₆ to a ₉ , b ₆ to b ₉ , and c ₆ to c ₉ can be determined experimentally. Note that the coefficients a ₁ to a ₉ , b ₁ to b ₉ , c ₁ to c ₉ and C1 to C9 are different values from a to c and C ₁ to C ₁₀ in the above formula.

According to the above formula, the heat source calculation unit 34k calculates the cooling water outlet temperature _Tdr using the cooling tower outlet temperature (cooling water inlet temperature) _Td calculated by the cooling tower calculation unit 34l, and the cooling tower calculation unit 34l calculates the cooling water outlet temperature Tdr. The calculation of determining the cooling tower outlet temperature _Td using the cooling water outlet temperature (cooling tower inlet temperature) _Tdr calculated by the heat source calculation unit 34k is repeated. 2). This is performed until the cooling tower outlet temperature (cooling water inlet temperature) T _d matches the set value (or approaches a certain allowable range (for example, the values match to the first decimal place)). If the cooling tower outlet temperature T _d does not reach the set value even after repeated calculations, it means that the cooling water cannot be cooled to the set value. In this case, the calculation is repeated until the cooling tower outlet temperature T _d matches the previous value (or approaches a certain allowable range (for example, the values match to the first decimal place)).

According to the above procedure, the power of each heat source device 1 can be calculated. Based on this, the power of the cooling water pump 4 can be calculated using a formula similar to the above formula (1). Further, the power of the fan of the cooling tower 2 can be calculated using the following equation.
Pw=CT _pw +Pw _rating
CT _pw = (T _dr - T _d sp)/(T _dr - T _d )

However, CT _pw : Cooling tower fan power ratio, T _d sp : Cooling tower outlet temperature lower limit set value (°C), Pw _rating : Cooling tower fan rated power (kW). Note that the power Pw of the fan of the cooling tower 2 calculated here is a value different from the power Pw of the supply air fan 10b and the return air fan 15a in the above equation.

By summing up the power of each part obtained by each calculation module in this way, it is possible to calculate the power of the entire air conditioning system including the primary side and the secondary side under a specific given condition. Note that the calculation procedure described here is just an example, and the formulas and parameters used in each calculation module, the order of calculations among calculation modules, etc. may be changed as appropriate.

Then, the optimization calculation section 33 performs similar calculations using the system model 34 under a plurality of different given conditions, and selects an operating condition that reduces the power of the entire system from the plurality of calculation results obtained. , inputs the set value of the secondary side water supply temperature under the operating conditions to the central monitoring device 31. The central monitoring device 31 operates the component devices of each part of the system (especially the primary heat source unit 1 and the cooling tower 2) based on the set value of the secondary side water supply temperature input from the optimization calculation unit 33. .

The selection of such operating conditions will be explained. In the above, it was first explained that, regarding the set value of the secondary side water supply temperature, for example, five different variance values from 7°C to 11°C are set, and the operating conditions are calculated for each case, but in this example, furthermore, Similarly, the operating conditions are calculated by setting a plurality of variance values for the outside air load ratio and the indoor load ratio, respectively. The purpose of calculating multiple cases for the setting of the secondary side water supply temperature is to find the setting value of the secondary side water supply temperature that minimizes the power for the entire system, but regarding the outdoor air load ratio and the indoor load ratio The purpose of calculating multiple cases is to increase the possibility of obtaining calculation results that are feasible in the system.

Each piece of equipment that makes up an air conditioning system has a limit to its achievable operating conditions; for example, a pump can only be operated between a maximum flow rate and a minimum flow rate. If we ignore these actual limitations, no matter what the secondary water supply temperature or other various values are, theoretically it is impossible to calculate the operating conditions as a calculation result under those conditions. can. However, there are cases where it is actually impossible to operate under the conditions calculated in this way. For example, when the secondary water supply temperature is raised, the flow rate of chilled water must be increased to cover the secondary load heat, but if the required flow rate exceeds the pump's rated output, this may not be possible in reality. Such operation cannot be performed, and it is unsuitable for simulating the operation of an air conditioning system. Similarly, depending on the given conditions, when a calculation is performed using a certain calculation module based on a certain value, the result may not be suitable for the operation of the corresponding equipment, or it may be possible to use the calculation result output from the first calculation module. When calculations are performed using another calculation module, the results may not be suitable for driving. In order to simulate the operating conditions of an actual air conditioning system, it is necessary to exclude these nonconforming calculation results and target realistic operating conditions.

Therefore, in this example, multiple variance values are set for each of the outdoor air load ratio and indoor load ratio, and the above calculations are performed for the cases where the outdoor air load and indoor load are each of these distributed values, and the non-conformity is detected. I am trying to exclude the calculation results. The remaining calculation results represent operating conditions suitable for (actually operable) the air conditioning system. From among them, first, those whose variance values of the outdoor air load ratio and the indoor load ratio are close to a predetermined reference value are extracted. Among the extracted operating conditions, the secondary side water supply temperature under the operating condition where the total power in the entire system is the smallest is specified, and the system is operated at the set value of the secondary side water supply temperature.

In addition, to exclude nonconforming calculation results, after all the calculations in the system model 34 as described above are completed, it is determined whether the calculated operating conditions are possible for each device, and even if there is a part that is impossible, It is also possible to discard the calculation results if there are any, but for example, in each of the above calculation modules, it is possible to set a compatibility range for each calculation result output by each module, so that the calculation result does not fall within the compatibility range. If the system model 34 is configured to output an error determination and cancel subsequent calculations if it is outside the range, unnecessary calculations can be omitted and the amount of calculations and the time required for calculations can be reduced.

The variance value and reference value of the outside air load ratio and indoor load ratio in the above calculation will be explained. In the above calculation example, the ratio of outside air intake to the supply air was set to 20% of the total, and the outside air load and indoor load were calculated based on this (note that the value of 20% is based on the outside air intake ratio in the actual air conditioning system). (In an air conditioning system, if the intake air volume of outside air or its set value is different from 20%, the load calculation should of course be based on that value.) The values of the outside air load and the indoor load calculated in this way are used as respective reference values.

Based on this reference value, the values of the outside air load ratio and the indoor load ratio are distributed, and a plurality of distributed values of the outside air load ratio and the indoor load ratio are set, respectively. For example, regarding the outside air load ratio, 11 values are set as distributed values in 1% increments from 95% to 105% of the calculated reference value. Regarding the indoor load ratio, five values are set as distributed values in 2.5% increments from 95% to 105% of the calculated reference value.

In this way, m types of variance values from x ₁ to x _m are set for the outdoor air load ratio, and n types from y ₁ to y _n are set for the indoor load ratio. Note that the numerical ranges of x ₁ to x _m and y ₁ to y _n (in the above example, 95% to 105%, respectively) and the number of each variance value (values of m and n; in the above example, 11 or 5 ), the interval between each variance value (1% or 2.5% in the example above) may be set as appropriate, not limited to the example above, but regarding the numerical range, it is within each numerical range. A reference value is included (that is, for example, when x ₁ ≦x _m , x ₁ ≦reference value ≦x _m ). Further, it is preferable that one of the variance values is set to be the same value as the reference value. (In the above example, the variance value at 100% corresponds to the reference value). As for the setting value of the secondary water supply temperature, one variance value is set from z ₁ to z _l (in the above example, 5 different values from 7° C. to 11° C.). Then, for the outside air load, there are m types of variance from x ₁ to x _m , for indoor loads, there are n types from y ₁ to y _n , and for the setting value of the secondary water supply temperature, there are l types of variance values from z ₁ to z _l . With each condition set as a given condition, calculation of the above operating conditions by the system model 34 is performed in a round-robin manner. That is, m×n×l calculations are performed (in the above example, 11×5×5=275 round-robin calculations are performed). From these calculation results, extract operating conditions that are realizable and in which the values of the outdoor air load ratio and indoor load ratio are close to the reference values (here, "operating conditions where the value of the outdoor air load ratio is closest to the reference value") It can be assumed that the value of the indoor load ratio is different from the operating condition where the value of the indoor load ratio is closest to the reference value, but in such a case, priorities should be set for each of these values and the operating conditions For example, first extract the "operating condition where the value of the outdoor air load ratio is closest to the reference value", and then, if there are multiple such operating conditions, extract the "value of the indoor load ratio" from there. It is only necessary to further extract the operating conditions in which the value is closest to the reference value). Among them, an operating condition with a small total power is selected, and a set value of the secondary water supply temperature under that operating condition is specified.

In addition to the secondary water supply temperature, here we will explain the case where distributed values are set for two values related to the secondary load heat amount, the outdoor air load ratio and the indoor load ratio, with the aim of ensuring possible calculation results. However, for targets where a variance value is set as a given condition other than the secondary water supply temperature, it is also possible to distribute only one of the outside air load ratio or the indoor load ratio and treat the other as 100%. . Alternatively, a variance value may be set for the secondary load heat amount (total amount of outside air load and indoor load) itself, and the operating conditions may be selected by performing calculations in the same manner as above. In addition, the target for setting the variance value may be any value related to the secondary load heat amount, such as sensible heat load, latent heat load, the ratio of outdoor air load to indoor load, or the ratio of sensible heat load to latent heat load in indoor load. , etc., the variance value may be similarly set. Moreover, the variance value may be set for only one type among these, or three or more types may be set.

The procedure for calculating such operating conditions can be summarized in a flowchart as shown in FIG. 4, for example. First, the secondary load heat amount is calculated from the operating status of the air conditioning system input to the central monitoring device 31, and based on this, the outside air load ratio and the indoor load ratio are calculated, and these values are used as reference values. The following variance values (x ₁ to x _m , y ₁ to y _n ) are set (step S1). Further, the dispersion value (z ₁ to z _l ) of the set value of the secondary side water supply temperature is set.

Next, from among the outside air load variance values, a variance value to be used for the first calculation is selected (step S2). In the first calculation, for example, x ₁ is used. Furthermore, a value to be used for the first calculation is selected from among the indoor load variance values (step S3). In the first calculation, for example, _y1 is used. Regarding the set value of the secondary water supply temperature, a variance value (for example, z ₁ ) used in the first calculation is also selected (step S4).

After selecting the distributed values to be used for calculations for the outside air load ratio, indoor load ratio, and secondary water supply temperature settings, the operating status of the heat source unit 1 and the air conditioner 10, and the outside air condition measured by the outside air sensor 35 are set to the center. Obtained from the monitoring device 31 (step S5). Using these as given conditions, operating conditions are calculated using the system model 34 (step S6).

After calculating the operating conditions based on one given condition setting in this way, it is determined whether there is an uncalculated distributed value of the secondary water supply temperature under the current outdoor air load and indoor load conditions (step S7 ). At the stage where the initial calculation using the outside air load x ₁ , the indoor load y ₁ , and the secondary water supply temperature z ₁ has been completed, the variance values of z ₂ to z _l have not yet been calculated. If there is an uncalculated variance value, return to step S4, select another variance value (for example, if z ₁ was used in the previous calculation, the next one is z ₂ ), and calculate the operating conditions again. (Steps S5 to S6). This is repeated until the lth time, and when there are no uncalculated variance values, the process proceeds to step S8.

In step S8, it is determined whether or not there is an uncalculated indoor load variance value under the current outside air load conditions. At the stage where the calculations using the outside air load x ₁ and the indoor load y ₁ have been completed, the variance values of y ₂ to y _n have not yet been calculated. If there is an uncalculated variance value, the process returns to step S3 and another variance value is selected. Under the newly selected indoor load dispersion value, the operating conditions are again calculated based on each dispersion value of the secondary water supply temperature (steps S4 to S6). This is repeated n times, and when there are no uncalculated variance values, the process proceeds to step S9.

In step S9, it is determined whether there is an uncalculated outside air load variance value. At the stage when the calculation based on the outside air load x ₁ has been completed, the variance values of x ₂ to x _m have not yet been calculated. If there is an uncalculated variance value, the process returns to step S2 and another variance value is selected. Under the newly selected indoor load variance value, the operating conditions are calculated again based on the indoor load and the secondary side water supply temperature variance values (steps S3 to S6). This is repeated until the mth time, and when there are no uncalculated variance values, the round-robin calculation of m×n×l operating conditions has been completed. At this stage, the process proceeds to step S10, where appropriate operating conditions are selected from the calculation results as described above, a setting value for the secondary water supply temperature that reduces the total power is specified, and based on this, the air conditioning system is driving.

Note that the procedure shown here is just an example, and the content of each step and the order of the steps may be changed as appropriate. For example, the acquisition of driving conditions (step S5) may be performed before step S2, or the order of round-robin calculations (steps S2 to S4, S7 to S9) may be changed. The distributed value of the secondary water supply temperature may be set in advance instead of being set together with other distributed values in step S1.

As shown in FIG. 2, when performing the above calculation assuming that the air conditioning system is equipped with N representative air conditioners 10' on the secondary side, this calculation should be performed at intervals of, for example, 15 to 20 minutes. I can do it. In this way, it is possible to automatically calculate in real time a set value for the secondary water supply temperature that will save energy for the entire air conditioning system, and to automatically perform operation based on this value.

Under conditions where the secondary load heat value is not high, such as during the middle of the year, winter, or at night or on rainy days, it is common to increase the secondary water supply temperature to save power for the heat source equipment and cooling tower, leading to energy savings. This is known in the art, and in the past, it has been practiced to save energy by manually changing the set value of the secondary water supply temperature depending on the situation. However, such manual operations largely depend on the operator's experience and intuition, and depending on the operator's skill level, it is not always possible to set the secondary water supply temperature to the optimal setting value each time, It could not be said that energy-saving operation by manipulating the water supply temperature was being carried out satisfactorily. As in this example, the operating status on the secondary side is calculated in real time, the secondary water supply temperature is calculated which requires less power for the entire system, and based on this, each device (especially the primary side heat source equipment If you operate the cooling tower 2), the system automatically calculates and executes the appropriate operating conditions at any time, so compared to conventional manual operation, the secondary water supply temperature can be adjusted at the appropriate timing, which is advantageous for energy saving. It is possible to make judgments and operate each device while making changes as needed, thereby further saving energy.

To do this, it is necessary to calculate the operating situation on the secondary side. In air conditioning systems, the configuration of the secondary side is generally complex, and attempting to calculate this requires a large amount of calculation, making it difficult to calculate in real time. Assuming an air conditioner, calculations were performed based on a virtual system with multiple representative air conditioners, thereby significantly reducing the calculation load. Although it is undeniable that the calculation accuracy of the operating conditions will be reduced somewhat by doing this, it will be possible to calculate the operating conditions in real time, and it will be possible to select the setting of the secondary water supply temperature that will save more energy each time to reduce energy consumption. It can be suppressed.

In addition, in order to avoid a situation in which it is not possible to calculate feasible operating conditions, multiple distributed values are set for each of the secondary load heat values (outside air load and indoor load) used in the calculation as a given condition, and the total By performing the hit calculation, it is possible to calculate realizable operating conditions while allowing a certain amount of calculation error. In this way, real-time energy-saving operation based on the operation status of the secondary side can be easily executed.

As described above, in this embodiment, the heat source device 1 is provided as the primary side device, and the plurality of air conditioners 10 are provided as the secondary side device, and cold water is circulated between the heat source device 1 and the air conditioner 10. Regarding the operating method of an air conditioning system configured to Using the system model 34, which is configured based on the assumption that a plurality of units are installed, the power of each component of the air conditioning system is calculated when the set value of the secondary water supply temperature is the above-mentioned variance value, and the power of each component is calculated. The dispersion value of the set value of the secondary side water supply temperature at which the total decreases is specified, and the air conditioning system is operated so that the secondary side water supply temperature becomes the specified dispersion value. In this way, it is possible to save energy in the operation of the air conditioning system by determining the secondary water supply temperature that is advantageous for energy conservation at an appropriate time and operating each part of the equipment according to the specified secondary water supply temperature. .

In addition, in this embodiment, a plurality of variance values are set for the secondary load heat amount or a value related thereto so that the numerical range includes a reference value, and the secondary load heat amount or a value related thereto is set to each of the variance values. Calculate the operating conditions of each component of the air conditioning system in the case of Based on the conditions, we identify the variance value of the secondary water supply temperature set value that reduces the total power, and operate the primary side equipment so that the secondary water supply temperature becomes the specified variance value. . In this way, it is possible to calculate realizable operating conditions while allowing for calculation errors.

In addition, in this embodiment, for the value related to the secondary load heat amount for which the distributed value is set, only one of the outdoor air load ratio and the indoor load ratio is distributed, and the other is treated as 100% (see above). In the example explained in , both are distributed).

In addition, in this embodiment, the value related to the secondary load heat amount for setting the dispersion value is determined based on the sensible heat ratio for mixing outside air and return air and introducing the mixture into the chilled water coil 10a. Based on the sensible heat load for heat treatment to a set temperature, the representative air conditioner air volume can be calculated from the sensible heat load, and the secondary return chilled water temperature and required flow rate can be calculated from the predetermined chilled water coil performance.

Furthermore, in this embodiment, the value related to the secondary load heat amount for setting the dispersion value can be obtained by calculating the secondary flow rate of cold water from the number of representative air conditioners in operation at any given time.

In addition, in this example, in order to make the secondary side water supply temperature a specified distributed value, the secondary side return chilled water temperature and the necessary Using the flow rate, the load factor of the refrigerator as the primary side of the heat source can be calculated, and the number of operating refrigerators can be calculated by receiving a signal of the number of refrigerators actually in operation.

Moreover, since the air conditioning system of this embodiment is configured to be able to execute the above-described operating method of the air conditioning system, it can achieve the same effects as described above.

Therefore, according to the present embodiment, the operating conditions of each device on the secondary side can be efficiently calculated, and based on this, the operation of each device can be optimized, thereby saving energy.

Note that the method of operating an air conditioning system and the air conditioning system of the present invention are not limited to the above-described embodiments, and it goes without saying that various changes may be made without departing from the gist of the present invention.

1 Heat source machine (refrigeration machine)
10 Air conditioner 10' Representative air conditioner 10a Chilled water coil 34 System model

Claims (7)

A method of operating an air conditioning system comprising at least a heat source machine as a primary side device and a plurality of air conditioners as a secondary side device, and configured such that cold water circulates between the heat source machine and the air conditioner, the method comprising:
A plurality of distributed values are set as a set value of a secondary water supply temperature that is a temperature of cold water on the upstream side of the air conditioner,
Using a system model that is constructed hypothetically assuming that multiple representative air conditioners with the same performance are installed, it is possible to calculate the power of each component of the air conditioning system when the set value of the secondary water supply temperature is the above-mentioned variance value. Calculate each
Identify the variance value of the secondary water supply temperature setting value that reduces the total power,
A method of operating an air conditioning system characterized by operating equipment on the primary side so that the temperature of water fed on the secondary side reaches a specified distributed value. Regarding the secondary load heat amount or related values, set multiple distributed values so that the numerical range includes the reference value,
Calculate the operating conditions of each component of the air conditioning system when the secondary load heat amount or the value related thereto is the respective variance value,
If there are multiple calculation results that allow operation, select the setting value of the secondary water supply temperature that reduces the total power from the operating conditions where the secondary load heat amount or the variance of the values related to it is closest to the reference value. Identify the variance value,
2. The method of operating an air conditioning system according to claim 1, further comprising operating equipment on the primary side so that the temperature of the water fed on the secondary side becomes a specified distributed value. According to claim 2, the value related to the secondary load heat amount for setting the distributed value is such that at least one of the outdoor air load ratio and the indoor load ratio is distributed, and the other is treated as 100%. How to operate the air conditioning system described. The value related to the secondary load heat amount that sets the dispersion value is the sensible heat load that is specified by the sensible heat ratio when mixing outside air and return air and introducing it into the chilled water coil, and then heat-treating the target room to the set temperature. According to claim 2 or 3, the representative air conditioner air volume is calculated from the sensible heat load, and the secondary return chilled water temperature and required flow rate are calculated from a predetermined chilled water coil performance. How to operate an air conditioning system. According to any one of claims 2 to 4, the value related to the secondary load heat amount for setting the dispersion value is obtained by calculating the secondary flow rate of chilled water from the number of representative air conditioners in operation at that time. How to operate the air conditioning system described. In order to make the secondary side water supply temperature a specified distributed value, the heat source primary The air conditioning system according to any one of claims 2 to 4, characterized in that the load factor of the refrigerator is calculated as a side, and the number of operating refrigerators is calculated by receiving a signal of the number of refrigerators actually in operation. how to drive. An air conditioning system characterized by the method of operating an air conditioning system according to any one of claims 1 to 6.

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