Air conditioning system operating method and air conditioning system

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

[Technical Field]

[0001] The present invention relates to a method for operating an air conditioning system in an energy-saving manner, and to an air conditioning system to which the method is applied. [Background technology]

[0002] In the field of air conditioning, energy conservation is, of course, one of the most important issues. There are a wide variety of specific approaches to achieving energy conservation, but in recent years, various technologies have been proposed and implemented to reduce energy consumption throughout the entire system by optimizing the operating conditions of each component of the air conditioning system. For example, Patent Document 1 listed below describes a technology that calculates the air conditioning load based on the inlet and outlet temperatures and flow rate of chilled water in a heat source unit, estimates state variables for optimally controlling the air conditioning equipment based on this, the air conditioning operating conditions (such as the volume of outside air intake and supply air temperature) and the outside air conditions, and controls the cooling tower fan, chilled water pump, chilled water pump, and compressor on the heat source unit side to match these state variables. Furthermore, Patent Document 2 listed below describes a technology that monitors the measured values ​​of the outside air wet-bulb temperature, the amount of heat generated by the heat source unit, and the chilled water outlet temperature while the air conditioning is operating, and based on this, performs optimization calculations 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 total amount of energy consumed in each heat source unit is minimized, thereby determining 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. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-256258 [Patent Document 2] Japanese Patent Application Publication No. 2017-101862 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the technologies described in Patent Documents 1 and 2, the calculation of the operating conditions of each device is basically limited to the heat supply side (primary side), and the secondary side that consumes heat is treated as the overall load from the heat supply side, which is the heat source. As a result, the optimization of operation has not yet been achieved by taking into account the operating conditions of the secondary side devices that consume heat. This is because the configuration of the secondary side in an air conditioning system is generally more complex than that of the primary side. Of course, it is theoretically possible to calculate the operating conditions of the secondary side, even if the configuration is complex. However, such calculations require a much greater load than calculating the primary side, and have not been realized on a practical basis. If it were possible to calculate the operating conditions of a system including the secondary side with a practically reasonable computational load and optimize the operating conditions of the entire system based on this, even greater energy savings would be achieved.

[0005] In view of the above circumstances, the present invention aims to provide an operating method for an air conditioning system that efficiently calculates the operating conditions of each secondary device, optimizes the operation of each device based on the calculated operating conditions, and achieves energy savings, as well as an air conditioning system to which the method is applied. [Means for solving the problem]

[0006] The present invention relates to a method for operating an air conditioning system that includes a heat source unit as a primary-side device and at least multiple air conditioners as secondary-side devices, and is configured so that chilled water circulates between the heat source unit and the air conditioners, wherein multiple variance values ​​are set as the set value of the secondary-side water supply temperature, which is the temperature of the chilled water upstream of the air conditioners, and a system model configured by assuming that multiple representative air conditioners with the same performance are installed is used to calculate the power of each component of the air conditioning system when the set value of the secondary-side water supply temperature is each of the variance values, and the variance value of the set value of the secondary-side water supply temperature that reduces the total power is identified, and the primary-side devices are operated so that the secondary-side water supply temperature becomes the identified variance value.

[0007] In the operating method of the air conditioning system of the present invention, multiple variance values ​​are set for the secondary load heat quantity or a value related thereto so that the numerical range includes a reference value, and the operating conditions of each component of the air conditioning system when the secondary load heat quantity or a value related thereto is each of the variance values ​​is calculated.If there are multiple calculation results that are operable, the variance value of the set value of the secondary side water supply temperature that reduces the total power is identified from the operating conditions where the variance value of the secondary load heat quantity or a value related thereto is closest to the reference value, and the primary side equipment can be operated so that the secondary side water supply temperature becomes the identified variance value.

[0008] In the operating method of the air conditioning system of the present invention, the value related to the secondary load heat quantity for setting the variance value can be distributed to at least one of the outdoor air load ratio or the indoor load ratio, with the other being treated as 100%.

[0009] In the method of operating the air conditioning system of the present invention, the value related to the secondary load heat quantity for setting the variance value is based on the sensible heat load, which is determined by the sensible heat ratio when mixing outside air and return air and introducing them into the chilled water coil, and then heat-treating them to the set temperature of the target room, and can be obtained by calculating the representative air conditioner airflow from the sensible heat load and calculating the secondary return chilled water temperature and required flow rate from the specified chilled water coil performance.

[0010] In the air conditioning system operating method of the present invention, the value relating to the secondary load heat quantity for setting the variance value can be determined by calculating the secondary chilled water flow rate from the number of representative air conditioners in operation at any given time.

[0011] In the operating method of the air conditioning system of the present invention, the chiller load factor as the primary heat source is calculated using the representative air conditioner air volume calculated from the sensible heat load and the secondary return chilled water temperature and required flow rate obtained from the specified chilled water coil performance so that the secondary side supply water temperature becomes a specified variance value, and the number of chillers in operation can be calculated by receiving a signal from the number of chillers actually in operation.

[0012] The present invention also relates to an air conditioning system configured to be able to execute the above-mentioned air conditioning system operating method. [Effects of the Invention]

[0013] According to the air conditioning system operating method and air conditioning system of the present invention, the operating conditions of each secondary device can be efficiently calculated, and the operation of each device can be optimized based on this, thereby achieving the excellent effect of saving energy. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a block diagram showing an example of a system configuration of an air conditioning system to which the present invention is applied; [Figure 2] 1 is a block diagram conceptually showing the concept of secondary-side operating conditions in an air conditioning system operating method according to an embodiment of the present invention. [Figure 3] 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. [Figure 4] 1 is a flowchart showing an example of a calculation procedure in an air conditioning system operation method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0016] Figure 1 shows an example of the system configuration of an air conditioning system to which the present invention is applicable. On the primary side (heat supply side) of the system, multiple chillers 1 are installed as heat source machines, and multiple cooling towers 2 are connected to each chiller 1 via a chilled water circulation path 3. A chilled water pump 4 is installed midway along the chilled water circulation path 3, and operation of the chilled water pump 4 circulates chilled water between the chillers 1 and the cooling towers 2. The chilled water pump 4 is equipped with an inverter-controlled motor, and its rotation speed can be changed as necessary to adjust the flow rate of the chilled water (the same applies to primary chilled water pump 8 and secondary chilled water pump 22, described below).

[0017] A primary chilled water flow path 5 is also connected to each chiller 1, and each chiller 1 cools the chilled water flowing through the primary chilled water flow path 5 using the cold energy of a high-temperature field resulting from heat exchange between the cooling water flowing through the cooling water circulation path 3 and the atmosphere, by causing a phase change of the refrigerant in the case of a vapor compression refrigeration cycle, or by absorbing the low-pressure vapor of water, the refrigerant, into an absorbing liquid in the case of an absorption refrigeration cycle. Multiple primary chilled water flow paths 5 extend from primary return headers 6 to primary outward headers 7, and chillers 1 are installed along each path. Inverter-controlled primary chilled water pumps 8 are installed upstream of the chillers 1 in the primary chilled water flow path 5, and operation of these primary chilled water pumps 8 drives the flow of chilled water from the primary return headers 6 through the chillers 1 to the primary outward headers 7. In addition, the primary return header 6 and the primary forward header 7 are connected by a bypass flow path 9, and when the flow rate of cold water on the primary side (primary cold water flow path 5) differs from the flow rate of cold water on the secondary side (secondary cold water flow path 16) described below, cold water is circulated between the primary return header 6 and the primary forward header 7 to adjust the differential pressure between the headers.

[0018] On the secondary side (heat consumption side) of the system, multiple air conditioners 10 are installed that supply conditioned air to the target space S. Each air conditioner 10 has a chilled water coil 10a through which chilled water flows and exchanges heat with air passing over its surface, and an inverter-controlled intake fan 10b that exchanges heat with the chilled water in the chilled water coil 10a and sends out the air that has received the chilled heat as conditioned air. The air outlet side of the air conditioner 10 is connected via an intake duct 11 to an intake port 12 of the target space S, from which the conditioned air is supplied to the target space S. A damper 13 is provided in the intake duct 11 just before the intake port 12, and by changing the opening of the damper 13, the amount of conditioned air blown out from the intake port 12 can be adjusted as needed.

[0019] Furthermore, a return air inlet 14 for taking in indoor air is provided at an appropriate position in the target space S, and the return air inlet 14 is connected to the air inlet side of the air conditioner 10 via a return air duct 15. An inverter-controlled return air fan 15a is provided in the return air duct 15, and when the return air fan 15a is operated, a portion of the indoor air in the target space S is taken in as return air through the return air inlet 14 and returned to the air conditioner 10 through the return air duct 15. The return air returned to the air conditioner 10 is again temperature-adjusted by the air conditioner 10 and sent out as supply air. As will be described later, the return air duct 15 of the air conditioner 10 enters the air conditioner 10 as mixed return air after it joins an outdoor air duct (not shown) that introduces outdoor air. It is also possible to fix the outdoor air supply ratio (OA ratio), for example, by mixing 20% ​​of the supply air volume as outdoor air with the return air.

[0020] A secondary chilled water flow path 16 is connected to the chilled water coil 10a inside the air conditioner 10, and chilled water is supplied to the chilled water coil 10a through the secondary chilled water flow path 16. The secondary chilled water flow path 16 extends from a secondary supply 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 a secondary return header 18. The secondary supply header 17 is connected to the primary supply header 7 via multiple communication paths 20, and the secondary return header 18 is connected to the primary return header 6 via a communication path 19. Of the multiple communication paths 20 connecting the primary supply header 7 and the secondary supply header 17, one communication path 20 is provided with a minimum flow valve 21, and the remaining communication paths 20 are provided with inverter-controlled secondary chilled water pumps 22. The secondary chilled water pump 22 sends chilled water from the primary feed header 7 to the secondary feed header 17 and drives the flow of chilled water from the secondary feed header 17 through the chilled water coil 10a of the air conditioner 10 to the secondary return header 18. The minimum flow valve 21 is opened as appropriate when the required amount of chilled water supplied from the primary feed header 7 to the secondary feed header 18 is small, and adjusts the required flow rate from the primary feed header 7 to the secondary feed header 18 without the secondary chilled water pump 22 operating at less than the minimum flow rate. A flow control valve 23 is installed downstream of the chilled water coil 10a in the secondary chilled water flow path 16, and the amount of chilled water flowing through the secondary chilled water flow path 16 is adjusted by the opening degree of the flow control valve 23.

[0021] In this way, in the air conditioning system shown in Figure 1, chilled water is circulated through a circular chilled water flow path consisting of a primary chilled water flow path 5, a secondary chilled water flow path 16, and each header 6, 7, 17, 18 and connecting passages 19, 20 by the action of a primary chilled water pump 8 and a secondary chilled water pump 22, while on the primary side, chilled water is circulated between the chiller 1 and the cooling tower 2 to cool the chilled water in the chiller 1, and on the secondary 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.

[0022] Furthermore, temperature sensors for measuring the temperatures of the cooling water, chilled water, and air, and flow meters for measuring the flow rates thereof are installed at various locations in the air conditioning system, and the operation of the air conditioning system as described above is performed while also referring to the measurements of these sensors as appropriate. In the example shown here, temperature sensors 24 for measuring the cooling water temperature are installed at the inlet and outlet of each cooling tower 2 in the cooling water circulation path 3, and temperature sensors 25 for measuring the chilled water temperature are installed at the outlet of each chiller 1 in the primary chilled water flow path 5. Temperature sensors 25 for measuring the chilled water temperature are also installed in the secondary supply header 17 and in the communication passage 19 between the secondary return header 18 and the primary return header 6. Furthermore, a temperature sensor 26 for measuring the supply air temperature is installed upstream of the damper 13 in the supply air duct 11.

[0023] An outside air duct (not shown) for taking in outside air is connected to the return air duct 15, and an outside air sensor 35 for measuring outside air conditions is provided in this duct. The outside air sensor 35 is, for example, a thermo-hygrometer, and measures outside air conditions such as temperature and humidity.

[0024] In addition, flow meters 27 are provided at positions upstream of each chiller 1 in the primary chilled water flow path 5 and in the middle of the communication passage 19 between the secondary return header 18 and the primary return header 6, to measure the flow rate of the chilled water at these positions.

[0025] The devices and sensors are interconnected as needed in terms of information via a communication network 28. Information devices such as a data collection server 29, a gateway device 30, and a central monitoring device 31 are connected to the communication network 28.

[0026] The data collection server 29 is the part that collects various data related to the operation of the air conditioning system, such as the operating status of each device and the measurement 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 chiller 1, cooling tower 2, cooling water pump 4, primary chilled water pump 8, secondary chilled water pump 22, minimum flow valve 21, and flow control valve 23. Measurement values ​​from temperature sensors 24, 25, and 26, flow meter 27, and outside air sensor 35 are also input and stored.

[0027] 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 and sensors of each device, as well as data stored in the data collection server 29, and inputs operation-related commands to each device.

[0028] Gateway device 30 connects communication network 28 to an external network (e.g., the Internet) 32. An optimization calculation unit 33, which is an information processing device such as a personal computer, is connected to Internet 32. This optimization calculation unit 33 incorporates a system model 34 that represents an information model of the entire air conditioning system. Based on various conditions acquired from data collection server 29 and central monitoring device 31 via external network 32, it calculates the operating conditions of each part of the system using a method described below, and identifies a set value for the secondary water supply temperature (the temperature of the chilled water upstream of air conditioner 10 in secondary chilled water flow path 16) that minimizes the total power consumed by each device. Central monitoring device 31 controls each device in real time to maintain the secondary water supply temperature at that value.

[0029] The controller (not shown) of the heat source, which is primarily the chiller 1, controls the operation of each part, such as the rotation speed of the chilled water pump 4 and primary chilled water pump 8, and the rotation speed and vane opening of the compressor in the chiller 1 via the chiller side panel, based on command signals input from the central monitoring device 31 via the network and information such as the flow rate and temperature of the chilled water and the cooling water in the pipes connected to the condenser, evaporator, etc. of the chiller 1. In addition, the controller (not shown) of each cooling tower 2 controls the rotation speed of the motor of the cooling tower fan provided in the cooling tower 2 based on command signals input from the central monitoring device 31 and information such as the outside air temperature and humidity and measurements of the temperature sensor 24 provided in the cooling water circulation path 3.

[0030] The controller (not shown) of the air conditioner 10 controls the opening of the flow rate adjustment valve 23 and the rotation speed of the supply air fan 10b and the return air fan 15a based on information such as command signals input from the central monitoring device 31, the set temperature input to the operation panel in the target space S, and temperature sensors 26 installed in the supply air duct 11. The controller (not shown) of the secondary chilled water pump 22 also controls the number of secondary chilled water pumps 22 in operation, the rotation speed of each pump, and the opening of the minimum flow valve 21 based on information such as command signals input from the central monitoring device 31 and measurements from temperature sensors 25 and flow meters 27 installed in various parts of the chilled water flow path.

[0031] The figures show simplified examples of the number and location of each device (heat source unit (chiller) 1, cooling tower 2, air conditioner 10, primary chilled water pump 8, secondary chilled water pump 22), the number of cooling towers 2 per chiller 1, the number of air conditioners 10 and dampers 13 installed relative to the target space S, the number and location of sensors (temperature sensors 24, 25, 26 and flow meter 27), the cooling water circulation path 3, primary chilled water flow path 5, secondary chilled water flow path 16, supply air duct 11, and return air duct 15. However, this is merely an example, and the drawings are schematic diagrams. The specific number and configuration of these devices, sensors, piping, etc. may be modified from the illustrated configuration as appropriate depending on the actual air conditioning system. The same applies to the configuration of control and information management components (data collection server 29, central monitoring device 31, optimization calculation unit 33, and system model 34). In addition, parts that are not directly related to the purpose of the present invention or parts that are not considered particularly necessary to be illustrated have been omitted from the illustrations as appropriate (for example, the aforementioned outside air duct, the outside air conditioning unit that conditions the outside air that is taken in, and sensors, on-off valves, and flow control valves attached to various parts not illustrated here).

[0032] In the air conditioning system of this embodiment, the optimization calculation unit 33 calculates the operating conditions of each piece of equipment, including the secondary side, and determines the secondary-side water temperature that will maximize energy conservation for the entire system. The optimization process and calculation procedures are described below. In this specification, the terms "equipment" and "component equipment" refer to equipment such as the heat source unit (chiller) 1, cooling tower 2, cooling water pump 4, air conditioner 10, damper 13, return air outlet 15a, minimum flow valve 21, secondary chilled water pump 22, temperature sensors 24, 25, and 26, flow meter 27, outdoor air sensor 35, and data collection server 29, as well as at least some of the equipment constituting the air conditioning system that is not listed here (or shown). In particular, when a phrase such as "operating equipment (system component equipment) based on the set value of the secondary-side water temperature" is used, the equipment to be operated includes at least one of the heat source unit (chiller) 1 and cooling tower 2, and may also include other equipment as necessary.

[0033] In this embodiment, a simplified model (system model 34) is used for the secondary side, which tends to have a complex actual configuration and incurs a huge computational load when calculations are performed on the operating conditions. This makes it possible to keep the amount of calculations to a practically feasible level while optimizing the entire system, taking into account the operating conditions on the secondary side.

[0034] In an actual air conditioning system, when multiple air conditioners 10 (see Figure 1) are installed, their types and performance often differ depending on the size and heat load conditions of the target space S they are responsible for. In addition, the configuration of the piping and ducts (secondary chilled water flow path 16, supply air duct 11, return air duct 15) and the thermal conditions of the target space S also differ depending on the location. When attempting to accurately simulate the operating conditions of each piece of secondary equipment, including the air conditioners 10, it is necessary to set and calculate these complex conditions individually for each air conditioner 10, resulting in an enormous calculation load.

[0035] Therefore, in this embodiment, as conceptually shown in FIG. 2, a system model 34 (see FIG. 1) is constructed by replacing each of the multiple air conditioners 10 installed on the secondary side with a virtual representative air conditioner 10' with the same performance. The virtual representative air conditioner 10' may be, for example, one of 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, the virtual representative air conditioner 10' may be set as an air conditioner with the performance of the average air conditioner 10, for example, by calculating the average performance value of each of the multiple air conditioners 10 installed in the air conditioning system. Then, it is assumed that the same number (N units) of these representative air conditioners 10' are installed in place of the air conditioners 10 actually installed. By constructing the system model 34 based on such assumptions, it is no longer necessary to perform calculations for each air conditioner 10 with different performance when calculating the operating conditions of the secondary system, thereby significantly reducing the calculation load. Note that, for components other than the air conditioner 10, appropriate omissions, averaging, approximations, and other processing may also be performed. For example, similarly, it may be assumed that there are multiple representative spaces S' with the same heat load, volume, set temperature, etc. for the target space S. Furthermore, the representative air conditioner and representative space are not limited to one type per system model, and representative air conditioners and representative spaces with multiple performance and specifications may be assumed. For example, if 10 air conditioners are installed, a configuration may be adopted in which one type of representative air conditioner is assumed for five units with similar performance, and a different type of representative air conditioner is assumed for the remaining five units.

[0036] Using the system model 34 created based on these settings, the operating conditions of each component of the air conditioning system are calculated based on the operating status of the primary heat source unit (chiller) 1, the operating status of the secondary air conditioner 10, the outdoor air conditions, and the secondary load heat quantity. Using the operating status of the chiller 1 and air conditioner 10, the outdoor air conditions, and the secondary load heat quantity as given conditions, the operating conditions of each device that can achieve an appropriate air conditioning state in the target space S are calculated. Then, the energy consumption of each device under those operating conditions is calculated, and these are summed to calculate the energy consumption of the entire air conditioning system.

[0037] This calculation is performed for each secondary-side water temperature, with the temperature of the chilled water sent out from the secondary feed header 17 (i.e., the temperature of the chilled water upstream of the air conditioner 10; hereinafter referred to as the "secondary-side water temperature") as a parameter, and multiple secondary-side water temperatures are set. That is, for example, for five different secondary-side water temperature settings, such as 7°C, 8°C, 9°C, 10°C, and 11°C, the operating conditions are calculated for each setting, and the energy consumption of the entire system is calculated for each setting (such multiple values ​​set for calculation are referred to as "variance values" below for convenience). Then, from the calculated operating conditions, the variance value that minimizes the energy consumption of the entire system is identified, and each device constituting the system, particularly the primary-side chiller 1 and cooling tower 2, is operated so that the secondary-side water temperature becomes the identified variance value.

[0038] Generally, the higher the secondary water temperature (i.e., the higher the target temperature of the chilled water to be cooled), the lower the energy consumption in the chiller 1 and cooling tower 2. Because the evaporation temperature in the chiller's evaporator increases, the temperature difference with the condenser in a vapor compression chiller decreases, reducing the compressor's workload. On the other hand, if the secondary water temperature is increased, the chilled water coil in the secondary air conditioner cannot compensate for the temperature difference between the chilled water going back and forth to cool the target air. This increases the amount of chilled water required to circulate on the secondary side to meet the heat load on the secondary side for the same amount of heat, resulting in increased energy consumption by equipment such as the primary chilled water pump 8 and the secondary chilled water pump 22. In other words, setting the secondary water temperature too high or too low can lead to increased energy consumption. Therefore, we find the secondary water temperature that minimizes the total energy consumption, and operate the air conditioning system to achieve the specified secondary water temperature.

[0039] 3 is a block diagram illustrating the configuration of the system model 34 and the calculation procedure performed by it. The system model 34 is equipped with a calculation module corresponding to each device in the air conditioning system so as to calculate the operating conditions for each device.

[0040] The system model 34 includes a secondary-side calculation unit 34a that calculates the operating conditions of each secondary-side device and a primary-side calculation unit 34b that calculates the operating conditions of each primary-side device. The secondary-side calculation unit 34a includes, as calculation modules, a room model 34c that calculates the thermal conditions in each target space S, an airflow calculation unit 34d that calculates the supply airflow rate of each air conditioner 10, a coil inlet air calculation unit 34e and a coil outlet air calculation unit 34f that calculate the air conditions upstream and downstream of the chilled water coil 10a, respectively, a coil chilled water calculation unit 34g that calculates the chilled water flow rate in the chilled water coil 10a and the chilled water temperature at the outlet of the chilled water coil 10a, a piping model 34h that calculates the amount of chilled water circulating on the secondary side, and a secondary pump model 34i that calculates the operating conditions of the secondary chilled water pump 22. Here, each module performs calculations for each part that makes up the air conditioning system, but the modules related to air conditioner 10 (air volume calculation unit 34d, coil inlet air calculation unit 34e, coil outlet air calculation unit 34f, 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 (in other words, the calculation results from representative air conditioner 10' are multiplied by N). Similarly, when a representative space S' is assumed for target space S, a room model 34c with the same load heat quantity, volume, set temperature, etc. is also assumed for room model 34c, and calculations for N rooms are performed using this.

[0041] The primary-side calculation unit 34b includes, as calculation modules, a heat source number control unit 34j that selects the number of operating chillers 1, which are heat source machines, and a heat source calculation unit 34k and a cooling tower calculation unit 34l that calculate the operating conditions of each chiller 1 and each cooling tower 2. The heat source calculation unit 34k and the cooling tower calculation unit 34l perform calculations for each chiller 1 and cooling tower 2 provided in the air-conditioning system.

[0042] The above system model 34 is - Heat load (sensible heat load and latent heat load) in the secondary room (target space S) - Set temperature and humidity in the target space S (room dry-bulb temperature set value, room relative humidity set value) Outside temperature and humidity (outside dry bulb temperature, outside relative humidity) - Air supply temperature and humidity settings (air supply temperature setting, air supply humidity setting) Exhaust airflow setting (exhaust airflow setting value) - Operating status of heat source equipment (number of operating chillers 1 and power of each unit) Air conditioner operation status (number of air conditioners in operation) Secondary water temperature setting Using the above as given conditions, the calculation modules corresponding to each component of the air conditioning system calculate values ​​related to the operating conditions of each component (load, energy consumption, etc.), and this calculates the power consumption of the entire system. Among the given conditions, the room dry-bulb temperature set value and room relative humidity set value are values ​​set in the target space S. Measurements from the outdoor air sensor 35 are used for the outdoor dry-bulb temperature and outdoor relative humidity. The supply air temperature set value, supply air humidity set value, and exhaust airflow set value are, in principle, fixed values ​​(although 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 air conditioner can also be obtained from the central monitoring device 31. As mentioned above, the secondary-side water supply temperature is set to an appropriate value, for example, between 7°C and 11°C, and used in the calculation. The secondary-side latent heat load and sensible heat load will be described later.

[0043] In the system model 34, first, the air volume calculation unit 34d calculates the supply air volume V S The value of (m 3 / h) is calculated using the following formula: V S =3,600ν·Q S / (1.006+1.805X S )·(T R sp-T S )

[0044] where ν is the specific volume of air (m 3 / kgDA), Q S : Sensible heat load (kW), X S : Absolute humidity of supply air (kg / kgDA), TR sp: Room dry-bulb temperature setting (℃), T S : supply air temperature setting value (℃), 1.006: specific heat at constant pressure of air (kJ / kg·K), 1.805: specific heat at constant pressure of water vapor (kJ / kg·K).

[0045] In the room model 34c, this supply air volume V S The values ​​of the indoor air temperature and humidity, and the return air volume are calculated using the indoor air temperature (indoor temperature T R (℃), absolute humidity of indoor air (indoor absolute humidity X R (kg / kgDA)), return air volume V R (m 3 / h) can be calculated using the following formulas: 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

[0046] However, Q L :Latent heat load (kW), V R :Return air volume (m 3 / h), V E : Exhaust air volume setting value (m 3 / h).

[0047] Indoor sensible heat load Q S and latent heat load Q L This can be calculated by the following procedure. First, the load heat quantity of the air conditioner 10 is calculated as the product of the temperature difference of the chilled water on the upstream and downstream sides of the chilled water coil 10a and the flow rate. The load heat quantity calculated in this way is the sum of the indoor load and the outdoor air load.

[0048] The air to be conditioned is a mixture of indoor air taken in as return air and outdoor air. The proportion of outdoor air in this mixture can be determined from the settings in the central monitoring device 31, the operating status of the air conditioner 10, the return air fan 15a, and the outdoor 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 outdoor air load per volume can be calculated from the difference between the outdoor air conditions (outdoor dry-bulb temperature, outdoor relative humidity) measured by the outdoor air sensor 35 and the supply air conditions (supply air temperature set value, supply air humidity set value). The indoor load can be calculated by subtracting the outdoor air load thus calculated from the load heat quantity calculated based on the product of the temperature difference and flow rate of the chilled water in the chilled water coil 10a.

[0049] The indoor load is further divided into sensible heat load and latent heat load, and the sensible heat ratio (the ratio of sensible heat load to indoor load) SHF is assumed to be, for example, 70%. This ratio is merely an assumption and is not necessarily a strictly accurate value, but this will give the sensible heat load Q S and latent heat load Q L The values ​​of can be calculated respectively.

[0050] The intake air volume V calculated above S and return air volume V R The power of the supply air fan 10b and the return air fan 15a can be calculated based on the above. 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

[0051] where a, b, c are coefficients calculated from the PQ diagram, P is pressure (Pa), Q is flow rate (m 3 / min), n: rotational speed, N: rated rotational speed, ρ: fluid density (1.2kg / m 3 ), g: Gravitational acceleration (9.8m / s 2 ), η: efficiency, Pw: power (kW). The flow rate Q in this formula is the sensible heat load Q S and latent heat load Q Lis a different value from the intake air volume V S and return air volume V R is substituted to find the power Pw of the supply air fan 10b and the return air fan 16a.

[0052] The coil inlet air calculation unit 34e calculates the outdoor air conditions (outdoor air dry bulb temperature and outdoor air relative humidity), the return air volume V R and condition (room temperature T R and indoor absolute humidity X R (This can be understood as the air volume of the supply air V S The mixing point is calculated from the state (supply air temperature set value and supply air humidity set value), and the temperature and absolute humidity of the air upstream of the chilled water coil 10a are calculated.

[0053] In the coil outlet air calculation unit 34f, the supply air volume V S and the state (supply air temperature set value and supply air humidity set value), the temperature and absolute humidity of the air downstream of the chilled water coil 10a are calculated.

[0054] The coil chilled water calculation unit 34g uses the number of coil rows (known value) to calculate the flow rate of chilled water circulating through the chilled water coil 10a and the temperature of the chilled water at the outlet side of the chilled water coil 10a from the upstream air conditions (temperature and humidity) calculated by the coil inlet air calculation unit 34e and the downstream air conditions (temperature and humidity) calculated by the coil outlet air calculation unit 34f. The amount of heat exchanged between the chilled water and air can be calculated from the difference in the air conditions on the upstream and downstream sides. Specific calculation procedures are, for example, as follows. First, the amount of heat exchanged qt (W) can be calculated as follows, assuming it is the same as the heat balance on the air side: qt=V S ×1.2×(hc ai hc ao )

[0055] However, hc ai : Enthalpy of air at the coil inlet (J / kg), hc ao : Enthalpy of air at the coil outlet (J / kg). On the other hand, the heat exchange quantity qt can also be expressed by the following formula: qt=Row×Kf×dtlm×Af×WSF

[0056] Where Row: number of coil rows, Kf: heat transfer coefficient (W / m 2 ·℃·Row), dtlm: Logarithmic mean temperature difference (℃), Af: Coil front area (m 2 ), WSF: Wetted Surface Factor.

[0057] The heat transfer coefficient Kf, logarithmic mean temperature difference dtlm, and wetted surface coefficient WSF can be expressed as follows: WSF=C1×SHF 2 +C2×SHF+C3 Kf=C4 / {1 / (C5+uf C6 +C7)+1 / (C8+vw C9 +C 10 )} dtlm=dt1·dt2 / ln(dt1 / dt2) dt1=tc ai ·tc wo dt2=tc ao ·tc wi

[0058] However, SHF is the above sensible heat ratio, C1 to C 10 is a coefficient provided by the manufacturer, uf: air speed of the supply air in front of the coil (m / s), vw: flow rate of the cold water passing through the coil (m / s), tc ai : Air temperature upstream of the coil (℃), tc wo : Coil outlet water temperature (℃), tc ao : Air temperature downstream of the coil (℃), tc wi : The coil inlet water temperature (℃). The front wind speed uf is the intake air volume V S The air temperature tc upstream and downstream of the coil can be calculated from the coil specifications based on the front wind speed uf. ai ,tc ao , the temperature of the cold water at the inlet side of the coil tc wi is a known value, and the coil outlet water temperature tc wo is an unknown quantity.

[0059] According to the above formula, the temperature tc of the cold water at the outlet side of the cold water coil 10a wo can be calculated, and the flow rate Q (L / min) of water in the chilled water coil 10a can be calculated using the following formula: Q=60×qt / {Cw×(tc wi -tc wo )}

[0060] where Cw is the mass specific heat of water (kJ / kg·°C). Note that the water flow rate Q in this formula is the sensible heat load Q mentioned above. S and latent heat load Q L , and is a different value from the fan flow rate (air volume) Q in the above formula.

[0061] In the piping model 34h, the flow rate of chilled water per air conditioner 10 thus determined is multiplied by the number of operating air conditioners 10 obtained from the central monitoring device 31 to calculate the total flow rate of chilled water on the secondary side.

[0062] The secondary pump model 34i and the heat source number control unit 34j calculate the number of operating heat source machines (refrigeration units) 1 from the total flow rate of chilled water on the secondary side, and calculate the power of the secondary chilled water pump 22 and the primary chilled water pump 8 based on the set value of the chilled water return temperature on the secondary side (which is the same as the outlet water temperature of the coil) and the secondary side supply water temperature.

[0063] Specifically, first, the flow rate in the bypass flow path 9 between the primary headers (primary supply header 7 and primary return header 6) is calculated from the total secondary chilled water flow rate calculated by the piping model 34h, taking into account the minimum flow rate of each heat source unit 1. Furthermore, the chilled water temperature in each primary and secondary header is calculated from the chilled water return temperature on the secondary side and the set value of the secondary side supply water temperature. The heat load calculated from the chilled water temperature and flow rate is allocated to each heat source unit 1 in accordance with the rated capacity ratio, and the number of operating heat source units 1 is determined. The number of operating secondary chilled water pumps 22 is determined from the secondary chilled water flow rate, and the primary side return water temperature (chilled water temperature in the primary return header 6) and secondary side supply water temperature (result value, not the set value) are calculated based on this water volume balance. Based on this, the power of the secondary chilled water pump 22 and the primary chilled water pump 8 can be calculated using a formula similar to the above formula (1).

[0064] The heat source calculation unit 34k and the cooling tower calculation unit 34l calculate the power of the heat source machine 1, the fan of the cooling tower 2, and the cooling water pump 4. As an example, the calculation procedure will be described when the heat source machine 1 is a centrifugal chiller.

[0065] Power consumption E of heat source unit 1 ref is the power consumption rate e ref and rated power consumption E ref_r is the product of E ref =e ref ×E ref_r

[0066] Power consumption rate e ref As shown in the following equation, the partial load factor influence coefficient C1, which is a function of the load factor q, and the cooling water inlet temperature T d The cooling water temperature influence coefficient C2, which is a function of the cooling water flow rate v d The cooling water flow rate ratio influence coefficient C3, which is a function of the cooling water outlet temperature T c The cooling water outlet temperature influence coefficient C4 is a function of the cooling water flow rate v c It can be expressed as the product of the parameter C1 and the chilled water flow rate influence coefficient C5. At rated conditions, the values ​​of C1 to C5 are 1.0, and e ref =1.0. e ref =C1×C2×C3×C4×C5 C1=a1q 2 +b1q+c1 C2=a2T d 2 +b2T d +c2 C3=a3v d 3 +b3v d 2 +c3v d +d3 C4=a4T c 2 +b4T c +c4 C5=a5v c 2 +b5v c +c5

[0067] Here, the chilled water outlet temperature T c is the temperature of the chilled water at the outlet of the chiller 1, and when the flow of chilled water in the bypass flow path 9 is not taken into consideration, the result value of the secondary side water temperature calculated above can be used. d is the temperature of the cooling water at the inlet of the chiller 1, and can be considered to be the same value as the temperature of the cooling water at the outlet of the cooling tower 2 (cooling tower outlet temperature) if the bypass of the cooling water circulation path 3 is not taken into consideration.

[0068] Above power consumption E ref Using the above, the cooling water outlet temperature (the temperature of the cooling water at the outlet of the refrigerator 1) T dr can be calculated using the following formula: q cd =q c +E ref =q c (1+1 / COP _qc ) V d =q cd / (T dr -T d )

[0069] However, q c :Cold water calorific value, COP _qc : Performance coefficient for each operating load factor, q cd :Cooling water heat value, V d : Cooling water flow rate.

[0070] On the other hand, on the cooling tower 2 side, the function T of the outside air wet bulb temperature WB ds , cooling tower inlet temperature (temperature of cooling water at the inlet of cooling tower 2) T dr The cooling tower inlet temperature influence coefficient C7, which is a function of the cooling water flow rate V d The cooling tower outlet temperature T d can be found as follows: T d =T ds ×C7×C8×C9 T ds =a6WB 2 +b6WB+c6 C7=a7Tdr 2 +b7T dr +c7 C8=f(C9,T dr ,WB) C9=a9V d 2 +b9V d +c9

[0071] The coefficients a1 to a5, b1 to b5, c1 to c5, and d3 are calculated from the diagrams provided by the manufacturer. The coefficients a6 to a9, b6 to b9, and c6 to c9 can be obtained experimentally. The coefficients a1 to a9, b1 to b9, c1 to c9, and C1 to C9 are the same as a to c and C1 to C in the above formulas. 10 is a different value.

[0072] According to the above formula, the heat source calculation unit 34k calculates the cooling tower outlet temperature (cooling water inlet temperature) T d Using the cooling water outlet temperature T dr The cooling tower calculation unit 34l calculates the cooling water outlet temperature (cooling tower inlet temperature) T dr Using the cooling tower outlet temperature T d (This calculation simulates the circulation of cooling water between the heat source (refrigerating machine) 1 and the cooling tower 2.) This is called the cooling tower outlet temperature (cooling water inlet temperature) T d Repeat the calculation until the cooling tower outlet temperature T d If the cooling tower outlet temperature T does not reach the set value, it means that the cooling water cannot be cooled to the set value. d The calculation is repeated until the value matches the previous value (or comes close to within a certain tolerance (e.g., the values ​​match to one decimal place)).

[0073] The above procedure allows the calculation of the power of each heat source unit 1. Based on this, the power of the cooling water pump 4 can be calculated using a formula similar to the above formula (1). In addition, the power of the fan of the cooling tower 2 can be calculated using the following formula. Pw=CT pw +Pw 定格 CT pw =(T dr -T d sp) / (T dr -T d )

[0074] However, CT pw : Cooling tower fan power ratio, T d sp: Cooling tower outlet temperature lower limit setting value (℃), Pw 定格 : Cooling tower fan rated power (kW). Note that the power Pw of the fan of the cooling tower 2 calculated here is a different value from the power Pw of the supply air fan 10b and the return air fan 15a in the above formula.

[0075] By adding up the power of each part calculated 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 secondary side, under specific given conditions. Note that the calculation procedure described here is merely an example, and the formulas and parameters used in each calculation module, the order of calculations between calculation modules, etc. may be changed as appropriate.

[0076] The optimization calculation unit 33 then performs similar calculations in the system model 34 under a plurality of different given conditions, selects operating conditions that will reduce the power consumption of the entire system from the obtained plurality of calculation results, and inputs the set value of the secondary side water supply temperature under those operating conditions to the central monitoring device 31. Based on the set value of the secondary side water supply temperature input from the optimization calculation unit 33, the central monitoring device 31 operates the components of each part of the system (in particular, the primary side heat source machine 1 and cooling tower 2).

[0077] The selection of such operating conditions will now be explained. First, five variance values, for example, from 7°C to 11°C, were set for the set value of the secondary-side water temperature, and the operating conditions were calculated for each case. In this embodiment, multiple variance values ​​are also set for the outdoor air load rate and the indoor load rate, and the operating conditions are calculated. The reason for calculating multiple settings for the secondary-side water temperature is to determine the set value for the secondary-side water temperature that minimizes the power consumption of the entire system, while the reason for calculating multiple settings for the outdoor air load rate and the indoor load rate is to increase the likelihood of obtaining calculation results that are feasible for the system.

[0078] Each component in an air conditioning system has its own set of achievable operating conditions. For example, a pump can only operate between maximum and minimum flow rates. If these practical limitations were ignored, it would theoretically be possible to calculate the operating conditions under any given set of values ​​for the secondary water temperature and other variables. However, operation under these calculated conditions may not actually be possible. For example, increasing the secondary water temperature requires a higher chilled water flow rate to meet the secondary load heat demand. However, if the required flow rate exceeds the pump's rated output, such operation is not possible in reality, making the simulation unsuitable for air conditioning system operation simulations. Similarly, depending on the given conditions, calculations performed using a certain calculation module based on certain values ​​may produce results that are inappropriate for the operation of the corresponding equipment. Or, calculations performed using the results output by one calculation module may also produce results that are inappropriate for operation. To simulate the operating conditions of a real air conditioning system, it is necessary to exclude these incompatible calculation results and focus on realistically feasible operating conditions.

[0079] Therefore, in this embodiment, multiple variance values ​​are set for the outdoor air load ratio and the indoor load ratio, and the above calculation is performed for each case where the outdoor air load and the indoor load are each of these variance values, and incompatible calculation results are excluded. The remaining calculation results represent operating conditions that are compatible with the air conditioning system (that are actually operable). From these, first, those with variance values ​​for the outdoor air load ratio and the indoor load ratio that are closest to pre-determined reference values ​​are extracted. From the extracted operating conditions, the secondary side water supply temperature under the operating condition that minimizes the total power consumption of the entire system is identified, and the system is operated at that set value for the secondary side water supply temperature.

[0080] Incidentally, the exclusion of incompatible calculation results can also be achieved by determining whether the calculated operating conditions are possible for each device after all calculations in the system model 34 as described above are completed, and discarding the calculation results if even one part is not possible. However, for example, if each of the calculation modules described above sets a compatibility range for the calculation results it outputs, and the system model 34 is configured so that if a calculation result is outside the compatibility range, an error is judged and subsequent calculations are stopped, unnecessary calculations can be omitted, thereby reducing the amount of calculation and the time required for calculation.

[0081] We will now explain the variance and reference values ​​for the outdoor air load ratio and indoor load ratio in the above calculation. In the calculation example above, the ratio of outdoor air intake to supply air was set to 20% of the total, and the outdoor air load and indoor load were calculated based on this. (Note that the value of 20% is based on the outdoor air intake volume in the actual air conditioning system. If the outdoor air intake volume or its set value in the air conditioning system is different from 20%, then the load calculation should naturally be based on that value as well.) The outdoor air load and indoor load values ​​calculated in this way are used as their respective reference values.

[0082] The values ​​of the outdoor air load ratio and indoor load ratio are distributed based on this reference value, and multiple variance values ​​for each are set. For example, for the outdoor air load ratio, 11 values ​​are set as variance values ​​in 1% increments from 95% to 105% of the calculated reference value. For the indoor load ratio, 5 values ​​are set as variance values ​​in 2.5% increments from 95% to 105% of the calculated reference value.

[0083] In this way, the outdoor air load ratio is x1 to x m m ways, and the indoor load ratio is y1~y n Set n different variance values ​​for x1 to x m and y1~y n The numerical ranges (95% to 105% in the above example), the number of each variance value (the values ​​of m and n; 11 or 5 in the above example), and the intervals between each variance value (1% or 2.5% in the above example) can be set as appropriate, not limited to the examples described above. However, the numerical ranges should include the reference value (for example, x1≦x m If x1≦reference value≦x m (The setting value of the secondary water temperature should be z1 to z2.) Also, it is recommended that one of the variance values ​​be set to the same value as the reference value. (In the above example, the variance value at 100% corresponds to the reference value.) The setting values ​​of the secondary water temperature should be z1 to z2. l Set the variance value for the outdoor air load (5 values ​​from 7℃ to 11℃ in the above example). m m ways, and for indoor loads, y1 to y n The set value of the secondary water temperature is z1 to z lThe system model 34 calculates the operating conditions in a brute-force manner, using the l variance values ​​as given conditions. That is, m × n × l calculations are performed (in the above example, 11 × 5 × 5 = 275 calculations are performed). From these calculation results, feasible operating conditions are extracted for which the outdoor air load ratio and indoor load ratio are close to the reference values. (Note that the "operating condition with the outdoor air load ratio closest to the reference value" and the "operating condition with the indoor load ratio closest to the reference value" may differ. In such cases, priorities can be assigned to these values, and the operating conditions can be narrowed down in order accordingly. For example, the "operating condition with the outdoor air load ratio closest to the reference value" is first extracted, and if there are multiple such operating conditions, the "operating condition with the indoor load ratio closest to the reference value" can be further extracted from there.) From these, the operating condition with the lowest total power is selected, and the setpoint value for the secondary water supply temperature for that operating condition is determined.

[0084] In this example, we have described a case where variance values ​​are set for two secondary load heat quantities, the outdoor air load ratio and the indoor load ratio, in addition to the secondary water supply temperature, in order to ensure the most feasible calculation results. However, it is also possible to set variance values ​​for only one of the outdoor air load ratio and the indoor load ratio, leaving the other at 100%. Alternatively, a variance value can be set for the secondary load heat quantity (the sum of the outdoor air load and the indoor load) itself, and the operating conditions can be selected by performing calculations similar to those described above. Furthermore, variance values ​​can be set for any value related to the secondary load heat quantity. For example, variance values ​​can be set for 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 the indoor load. Variance values ​​can be set for only one of these, or for three or more.

[0085] The calculation procedure for such operating conditions can be summarized in a flowchart as shown in Fig. 4. First, the secondary load heat quantity is calculated from the operating status of the air conditioning system input to the central monitoring device 31, and based on this, the outdoor air load ratio and the indoor air load ratio are calculated. These values ​​are used as reference values, and multiple variance values ​​(x1 to x m , y1~y n ) is set (step S1). In addition, the variance values ​​(z1 to z l ) to set the

[0086] Next, from the variance values ​​of the outdoor air load, a variance value to be used in the initial calculation is selected (step S2). In the initial calculation, for example, x1 is used. Furthermore, from the variance values ​​of the indoor load, a value to be used in the initial calculation is selected (step S3). In the initial calculation, for example, y1 is used. For the set value of the secondary side water supply temperature, a variance value to be used in the initial calculation (for example, z1) is also selected (step S4).

[0087] After selecting the variance values ​​to be used in the calculation for the set values ​​of the outdoor air load ratio, indoor load ratio, and secondary side water temperature, the operating status of the heat source unit 1 and the air conditioner 10, as well as the outdoor air conditions measured by the outdoor air sensor 35, are obtained from the central monitoring device 31 (step S5). Using these as given conditions, the operating conditions are calculated using the system model 34 (step S6).

[0088] Once the calculation of the operating conditions based on one given condition setting is completed, it is determined whether there is an uncalculated variance value of the secondary side water temperature under the current outdoor air load and indoor load conditions (step S7). After the initial calculation based on the outdoor air load x1, the indoor load y1, and the secondary side water temperature z1 is completed, z2 to z l The variance values ​​of z1 and z2 have not been calculated yet. If there are any uncalculated variance values, return to step S4, select another variance value (if z1 was used in the previous calculation, for example, z2 will be used next), and calculate the operating conditions again (steps S5 to S6). This is repeated up to the lth time, and when there are no more uncalculated variance values, proceed to step S8.

[0089] In step S8, it is determined whether there is an uncalculated indoor load variance value under the current outdoor air load condition. n The variance values ​​for the following have not been calculated. If there are any uncalculated variance values, return to step S3 and select another variance value. Under the newly selected indoor load variance value, calculate the operating conditions again based on each variance value of the secondary side water temperature (steps S4 to S6). This is repeated n times, and when there are no more uncalculated variance values, proceed to step S9.

[0090] In step S9, it is determined whether there is an uncalculated variance value of the outdoor air load. m The variance value of the indoor load has not yet been calculated. If there is an uncalculated variance value, return to step S2 and select another variance value. Using the newly selected indoor load variance value, calculate the operating conditions again based on the variance values ​​of the indoor load and secondary water temperature (steps S3 to S6). This is repeated m times, and when there are no more uncalculated variance values, the brute force calculation of m × n × l operating conditions has been completed. At this stage, proceed to step S10, select appropriate operating conditions from the calculation results as described above, identify the set value of the secondary water temperature that will reduce the total power, and operate the air conditioning system based on this.

[0091] The procedure shown here is merely an example, and the content of each step and the order of steps may be changed as appropriate. For example, the acquisition of the operating status (step S5) may be performed before step S2, or the order of the brute force calculations (steps S2 to S4, S7 to S9) may be reversed. The variance value of the secondary side water temperature may be set in advance rather than being set together with the other variance values ​​in step S1.

[0092] As shown in Figure 2, when performing the above calculations assuming that the air conditioning system is equipped with N representative air conditioners 10' on the secondary side, this calculation can be performed, for example, at intervals of 15 to 20 minutes. In this way, the set value for the secondary side water supply temperature that will result in energy savings for the entire air conditioning system can be calculated automatically in real time, and operation based on this can be performed automatically.

[0093] It is generally known that increasing the secondary water temperature can reduce the power consumption of heat source equipment and cooling towers, leading to energy savings, under conditions where the secondary heat load is not high, such as during the transitional seasons, winter, nighttime, or rainy weather. Conventionally, energy savings have been achieved by manually adjusting the secondary water temperature setting depending on the situation. However, such manual operation relies heavily on the operator's experience and intuition, and depending on the operator's level of proficiency, it is not always possible to optimally set the secondary water temperature. Therefore, energy-saving operation through adjustment of the secondary water temperature has not been fully achieved. In this embodiment, the system calculates the secondary operating conditions in real time, calculates the secondary water temperature that requires less power for the entire system, and operates each device (particularly the primary-side heat source equipment 1 and cooling tower 2) based on this calculation. Therefore, compared to conventional manual operation, the system can determine the optimal secondary water temperature at the appropriate time and adjust it as needed to operate each device, thereby achieving further energy savings.

[0094] To do this, it is necessary to calculate the operating conditions on the secondary side. In air conditioning systems, the secondary side configuration is generally complex, and calculating this requires a large amount of calculation, making real-time calculations difficult. However, in this embodiment, a representative air conditioner is assumed as the air conditioner in the calculations, and calculations are performed on a virtual system equipped with multiple identical representative air conditioners, thereby significantly reducing the calculation load. Although this does result in a slight decrease in the accuracy of the calculation of the operating conditions, it does make it possible to calculate the operating conditions in real time, and it is possible to reduce energy consumption by selecting the secondary side water supply temperature setting each time to achieve greater energy savings.

[0095] In addition, to avoid situations where it is not possible to calculate feasible operating conditions, multiple variance values ​​are set for the secondary load heat quantity values ​​(outdoor air load and indoor load) used in the calculation as given conditions, and a brute force calculation is performed, allowing for a certain degree of calculation error and allowing for the calculation of feasible operating conditions.In this way, it is possible to smoothly perform real-time energy-saving operation based on the secondary side operating status.

[0096] As described above, this embodiment relates to a method for operating an air conditioning system including a heat source unit 1 as a primary-side device and multiple air conditioners 10 as secondary-side devices, with chilled water circulating between the heat source unit 1 and the air conditioners 10. Multiple variances are set for the secondary water temperature (i.e., the temperature of the chilled water upstream of the air conditioners 10). Using a system model 34 configured to simulate multiple representative air conditioners 10' with identical performance, the system calculates the power required for each component of the air conditioning system when the secondary water temperature is set to each of the variances. The system then identifies the variances for the secondary water temperature that minimize the total power required, and operates the air conditioning system so that the secondary water temperature is set to the identified variance. In this way, the system can achieve energy savings by determining the optimal secondary water temperature at the appropriate time and operating each component at the identified secondary water temperature.

[0097] In this embodiment, multiple variance values ​​are set for the secondary heat load or a value related thereto so that the numerical range includes the reference value, and the operating conditions of each component of the air conditioning system when the secondary heat load or a value related thereto is each of the variance values ​​is calculated. If there are multiple calculation results that are operable, the variance value of the set value of the secondary-side water supply temperature that reduces the total power is identified from the operating conditions where the variance value of the secondary heat load or a value related thereto is closest to the reference value, and the primary-side equipment is operated so that the secondary-side water supply temperature becomes the identified variance value. In this way, feasible operating conditions can be calculated while allowing for calculation errors.

[0098] In addition, in this embodiment, the value related to the secondary load heat quantity for setting the variance value is distributed to only one of the outdoor load ratio or the indoor load ratio, and the other is treated as 100% (in the example described above, both are distributed).

[0099] In addition, in this embodiment, the value related to the secondary load heat quantity for setting the variance value is based on the sensible heat load, which is determined by the sensible heat ratio when mixing outside air and return air and introducing them into the chilled water coil 10a, and then heat-treating them to the set temperature of the target room, and can be obtained by calculating the representative air conditioner air volume from the sensible heat load and calculating the secondary return chilled water temperature and required flow rate from the specified chilled water coil performance.

[0100] In this embodiment, the value relating to the secondary load heat quantity for setting the variance value can be determined by calculating the secondary chilled water flow rate from the number of representative air conditioners in operation at any given time.

[0101] In addition, in this embodiment, the chiller load factor as the primary heat source is calculated using the representative air conditioner air volume calculated from the sensible heat load and the secondary return chilled water temperature and required flow rate obtained from the specified chilled water coil performance, so that the secondary side supply water temperature becomes a specified variance value, and the number of chillers in operation can be calculated by receiving a signal indicating the number of chillers actually in operation.

[0102] Furthermore, the air conditioning system of this embodiment is configured to be able to execute the above-described air conditioning system operating method, and therefore can achieve the same effects as those described above.

[0103] Therefore, according to the present embodiment, the operating conditions of each device on the secondary side can be efficiently calculated, and the operation of each device can be optimized based on the calculated operating conditions, thereby achieving energy savings.

[0104] The air conditioning system and method of operating the air conditioning system of the present invention are not limited to the above-described embodiment, and it goes without saying that various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0105] 1 Heat source machine (refrigeration machine) 10 Air conditioner 10' representative air conditioner 10a Chilled Water Coil 34 System Model

Claims

1. An operating method for an air conditioning system including a heat source unit as a primary side device and a plurality of air conditioners as secondary side devices, and configured so that chilled water circulates between the heat source unit and the air conditioners, A plurality of variance values ​​are set as a set value of a secondary water supply temperature, which is the temperature of chilled water on the upstream side of the air conditioner; Using a system model configured assuming that multiple representative air conditioners with the same performance are installed, calculate the power of each component of the air conditioning system when the set value of the secondary water supply temperature is each of the variance values, Identify the variance value of the set value of the secondary water supply temperature that reduces the total power, Operate the primary equipment so that the secondary water temperature is at the specified variance value. A method for operating an air conditioning system, comprising:

2. Regarding the secondary load heat quantity or values ​​related thereto, multiple dispersion values ​​are set so that the numerical range includes the reference value, Calculating the operating conditions of each component of the air conditioning system when the secondary load heat quantity or a value related thereto is each of the variance values; If there are multiple calculation results that are operable, identify the variance value of the set value of the secondary side water supply temperature that reduces the total power from the operating conditions in which the variance value of the secondary load heat quantity or a value related thereto is closest to the reference value; Operate the primary equipment so that the secondary water temperature is at the specified variance value.

2. The method for operating an air conditioning system according to claim 1,

3. The value related to the secondary load heat quantity for which the dispersion value is set is distributed to at least one of the outdoor air load rate or the indoor air load rate, and the other is treated as 100%.

3. The method for operating an air conditioning system according to claim 2, further comprising:

4. The value related to the secondary load heat quantity for setting the variance value is determined based on the sensible heat load that is determined by mixing outside air and return air, introducing the air into the chilled water coil, and then heat treating it to the set temperature of the target room, by calculating the representative air flow rate of the air conditioner from the sensible heat load, and then calculating the secondary return chilled water temperature and required flow rate from the specified chilled water coil performance.

4. The method for operating an air conditioning system according to claim 2 or 3,

5. The value related to the secondary load heat quantity for setting the variance value is obtained by calculating the secondary chilled water flow rate from the number of representative air conditioners in operation at that time.

5. The method for operating an air conditioning system according to claim 2, wherein:

6. An operating method for an air conditioning system according to any one of claims 2 to 4, characterized in that the chiller load factor as the primary heat source is calculated using the representative air conditioner air volume calculated from the sensible heat load and the secondary return chilled water temperature and required flow rate obtained from the specified chilled water coil performance so that the secondary side supply water temperature becomes a specified variance value, and the number of chillers in operation is calculated by receiving a signal of the number of chillers actually in operation.

7. An air conditioning system comprising the method for operating an air conditioning system according to any one of claims 1 to 6.

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