Air conditioning system and method of controlling air conditioning system

Abstract

To provide an air conditioning system and a method of controlling an air conditioning system that can reduce energy consumption when constant differential pressure control is executed.SOLUTION: An air conditioning system 1 for performing variable flow rate control of cold and hot water by constant differential pressure control includes: a heat source 60 for heating or cooling cold and hot water; a plurality of air conditioners 40 within which cold and hot water circulate; a cold and hot water pump 20 that supplies cold and hot water to the air conditioners 40; a piping 30 connecting the heat source 60, the cold and hot water pump 20 and the air conditioners 40; an air outlet sensor 47 that detects an air blowing temperature of the air conditioners 40; a pump output setting unit 90 for setting a cold and hot water pump output of the cold and hot water pump 20; and a control section 70 for operating the cold and hot water pump 20 at the cold and hot water pump output set by the pump output setting unit 90. The pump output setting unit 90 sets the cold and hot water pump output of the cold and hot water pump 20 so that the air blowing temperature of the air conditioners 40 detected by the air outlet sensor 47 is within an air blowing temperature range required for air conditioning temperature control.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air conditioning system and a method for controlling an air conditioning system. [Background technology]

[0002] Known conventional air conditioning systems include, for example, the air conditioning system described in Patent Document 1. This conventional air conditioning system includes a heat source, a plurality of air conditioners installed indoors and connected to the heat source by hot and cold water piping, and a pump installed in the hot and cold water piping to circulate the hot and cold water between the heat source and the air conditioners.

[0003] In addition, a known conventional air conditioning system uses constant differential pressure control to stabilize the flow rate of chilled or hot water flowing to each air conditioner by maintaining a constant differential pressure, which is the difference between the pressure of chilled or hot water delivered from the pump and the pressure of chilled or hot water flowing into the pump. Among the multiple air conditioners in this air conditioning system, the air conditioner located farthest from the pump experiences the greatest pressure loss of chilled or hot water due to piping resistance between the pump and the air conditioner. Therefore, in this type of constant differential pressure control, the differential pressure of the chilled or hot water circulation is set so that the pressure of the chilled or hot water supplied to the air conditioner located farthest from the pump is sufficient to operate the air conditioner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-173221 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when constant differential pressure control is implemented in conventional air conditioning systems, the differential pressure of the chilled / hot water circulation is set according to the air conditioner located farthest from the pump, as described above, so the pressure of the chilled / hot water supplied to the air conditioner located closest to the pump becomes excessively high. As a result, the pressure of the chilled / hot water supplied to the air conditioner located closest to the pump is reduced by applying resistance using a control valve in the connected piping, which poses a problem of large energy consumption by the air conditioning system.

[0006] The present invention has been made to solve such problems, and aims to provide an air conditioning system and a control method for an air conditioning system that can reduce the energy consumed when performing constant differential pressure control. [Means for solving the problem]

[0007] In order to solve the above problems, the air conditioning system of the present invention comprises a heat source for heating or cooling chilled or hot water, a plurality of air conditioners through which chilled or hot water circulates, a chilled or hot water pump for supplying chilled or hot water to each air conditioner, piping connecting the heat source, the chilled or hot water pump, and each air conditioner, an air supply temperature detection unit for detecting the air supply temperature of each air conditioner, a pump output setting unit for setting the chilled or hot water pump output of the chilled or hot water pump, and a control unit for operating the chilled or hot water pump at the chilled or hot water pump output set by the pump output setting unit, and the pump output setting unit sets the chilled or hot water pump output of the chilled or hot water pump so that the air supply temperature of each air conditioner detected by the air supply temperature detection unit is within the air supply temperature range required for air conditioning temperature control.

[0008] In addition, the pump output setting unit may set the chilled / hot water pump output so as to reduce the differential pressure, which is the difference between the pressure of the chilled / hot water discharged from the chilled / hot water pump and the pressure of the chilled / hot water flowing into the chilled / hot water pump, when the blowing air temperature of each air conditioner is within the blowing air temperature range, and may set the chilled / hot water pump output so as to increase the differential pressure when the blowing air temperature of each air conditioner is outside the blowing air temperature range. In addition, the pump output setting unit may set the cold / hot water pump output so that the differential pressure becomes a predetermined specified differential pressure when the air supply temperature of each air conditioner is equal to or higher than a predetermined value relative to the upper limit of the air supply temperature range or is equal to or lower than a predetermined value relative to the lower limit of the air supply temperature range.

[0009] In addition, in order to solve the above-mentioned problems, a control method for an air conditioning system according to the present invention is a control method for an air conditioning system including a heat source for heating or cooling chilled or hot water, a plurality of air conditioners through which chilled or hot water circulates, a chilled or hot water pump for supplying chilled or hot water to each of the air conditioners, piping connecting the heat source, the chilled or hot water pump, and each of the air conditioners, a blower temperature detection unit for detecting the blower temperature of each of the air conditioners, a pump output setting unit for setting the chilled or hot water pump output of the chilled or hot water pump, and a control unit for controlling the chilled or hot water pump with the chilled or hot water pump output set by the pump output setting unit, the control method including the steps of: the blower temperature detection unit detecting the blower temperature of each of the air conditioners; and, when the blower temperature of each air conditioner detected by the blower temperature detection unit is within a blower temperature range required for air conditioning temperature control, the pump output setting unit setting the chilled or hot water pump output so as to reduce the differential pressure, and when the blower temperature of each air conditioner is outside the blower temperature range required for air conditioning temperature control, the pump output setting unit setting the chilled or hot water pump output so as to increase the differential pressure. [Effects of the Invention]

[0010] The air conditioning system and control method for the air conditioning system of this invention include an air conditioning system having a heat source for heating or cooling chilled or hot water, a plurality of air conditioners through which chilled or hot water circulates, a chilled or hot water pump for supplying chilled or hot water to each air conditioner, piping connecting the heat source, the chilled or hot water pump, and each air conditioner, an air supply temperature detection unit for detecting the air supply temperature of each air conditioner, a pump output setting unit for setting the chilled or hot water pump output of the chilled or hot water pump, and a control unit for operating the chilled or hot water pump at the chilled or hot water pump output set by the pump output setting unit, wherein the pump output setting unit sets the chilled or hot water pump output of the chilled or hot water pump so that the air supply temperature of each air conditioner detected by the air supply temperature detection unit is within the air supply temperature range required for air conditioning temperature control, thereby reducing the energy consumed when performing constant differential pressure control. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram of an air conditioning system according to an embodiment of the present invention. [Figure 2] 1. FIG. 4 is a first model diagram for examining the required differential pressure for constant differential pressure control in the air conditioning system 1 shown in FIG. [Figure 3] FIG. 2 is a second model diagram for examining the pressure difference in variable flow rate control in the air conditioning system shown in FIG. [Figure 4] 3 is a flowchart showing the operation of the air conditioning system 1 of the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] (Air conditioning system configuration) An embodiment of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram of an air conditioning system according to the present embodiment. Air conditioning system 1, installed in a facility or building (not shown), includes a heat source 60, a chilled / hot water pump 20 for circulating chilled / hot water flowing from heat source 60, and piping 30 through which chilled / hot water pump 20 is installed and through which the chilled / hot water flows. Piping 30 includes an inlet piping 31 and an outlet piping 32. Inlet piping 31 branches and is connected to the inlets of a plurality of air conditioners 40 installed, for example, on each floor or in each room of the building. Heat source 60 may be any heat source, including, for example, a heat pump chiller, a chiller / heater, a turbo chiller, or a boiler. Alternatively, heat exchangers or a receiving unit for chilled / hot water supplied from outside the building may be used.

[0013] The air conditioner 40 has an air intake 41 that takes in ambient air, a fan 42, an air conditioning coil 43, and an outlet 44 that blows out cool or warm air. The air intake 41 has an air intake sensor 46 that detects the temperature, humidity, and air volume of the air being taken in. The outlet 44 has an outlet sensor 47 that detects the air temperature, humidity, and air volume of the air being blown out. The air intake sensor 46 and the outlet sensor 47 make up an air conditioning load detection unit.

[0014] An inlet pipe 31 is connected to the inlet side of the air conditioner coil 43, and chilled or hot water flows in from the inlet pipe 31. An outlet pipe 32 is connected to the outlet side of each air conditioner coil 43. The outlet pipes 32 join and are connected to a heat source 60, and the chilled or hot water flowing out of the air conditioner coil 43 joins via the outlet pipe 32 and then flows into the heat source 60. A control valve 50 is provided in the outlet pipe 32 for each air conditioner 40 to control the chilled or hot water flow rate of the air conditioner coil 43 of each air conditioner 40. The opening of each control valve 50 is controlled by an air conditioner control unit 45 provided in each air conditioner 40. A detector 80 is provided at the junction of the outlet pipe 32 to measure the chilled or hot water flow rate when the chilled or hot water that has flowed through the air conditioner coil 43 of each air conditioner 40 flows into the heat source 60 after joining. The chilled / hot water pump 20, piping 30, inlet piping 31, outlet piping 32, air conditioner coil 43, control valve 50, and heat source 60 constitute the chilled / hot water system of the air conditioning system 1. Each control valve 50 has a flow rate detection unit (not shown) that measures the internal pressure difference of the control valve 50 to detect the flow rate of chilled / hot water flowing through the control valve 50. In other words, the control valve 50 constitutes the air conditioner flow rate detection unit. The control unit 70 can obtain the detection result of the flow rate detection unit via the electrically connected air conditioner control unit 45.

[0015] An inverter 21 that controls and drives the chilled / hot water pump 20 is connected to the inverter 21. A control unit 70 that controls the entire air conditioning system 1 is connected to the inverter 21. The control unit 70 may be part of, for example, a known building energy management system (BEMS). The control unit 70 is connected to an outdoor air specific enthalpy detection unit 81 that includes an outdoor temperature and humidity detection unit and the like that detects the outdoor air specific enthalpy of the outdoor air, an air conditioning load detection unit 82 that is connected to the inlet sensor 46 and the outlet sensor 47 of each air conditioner 40 and detects the air conditioning load of each air conditioner 40, a power detection unit 83 that detects the power consumption of electrical equipment used in the air conditioning range of the air conditioner in the building in which each air conditioner 40 is installed, a pump output setting unit 90 that sets the output of the chilled / hot water pump 20, and the air conditioner control unit 45. The pump output setting unit 90 stores a setting table for the flow rate and required differential pressure of the piping flow path that supplies chilled or hot water to each air conditioner 40 of the chilled or hot water pump 20. Based on this setting table, the pump rotation speed for the target pump flow rate and the control value of the inverter 21 for controlling the chilled or hot water pump 20 at that pump rotation speed are set. Note that, if the differential pressure of the terminal air conditioner 40 is detected, a setting table may not be provided, and only the terminal differential pressure may be set. The detector 80, the outdoor air specific enthalpy detection unit 81, which includes an outdoor temperature and humidity detection unit, the air conditioning load detection unit 82, and the power detection unit 83 constitute a condition detection unit. The control unit 70 and the air conditioner control unit 45 constitute a control unit. The pump rotation speed of the chilled or hot water pump 20 correlates with the output of the chilled or hot water pump 20. For example, the cube of the pump rotation speed of the chilled or hot water pump 20 divided by the efficiency reduction of the component equipment corresponds to the output of the chilled or hot water pump 20.

[0016] When the air conditioning system 1 is operating, the chilled / hot water pump 20 circulates the chilled / hot water flowing out from the heat source 60 to each air conditioner 40, and the chilled / hot water that has flowed through each air conditioner 40 flows through the control valve 50 and into the heat source 60, thereby circulating the chilled / hot water through the chilled / hot water system. At this time, the differential pressure at which the chilled / hot water pump 20 circulates the chilled / hot water is controlled by the control unit 70 controlling the output frequency of the inverter 21 based on the pump output set by the pump output setting unit 90, and operating the chilled / hot water pump 20 at this output frequency.

[0017] (Study of the required differential pressure for constant differential pressure control in air conditioning systems) Fig. 2 is a first model diagram for examining the required differential pressure for constant differential pressure control in the air conditioning system 1 shown in Fig. 1. Here, the differential pressure in this control refers to the difference in chilled / hot water pressure between the upstream and downstream sides in a certain section of the chilled / hot water flow path including the pipe 30, the inlet pipe 31, and the outlet pipe 32. In the air conditioning system 1, the differential pressure provided by the chilled / hot water pump 20 is reduced by flow path resistance, which is the resistance in the chilled / hot water system in the entire chilled / hot water flow path of the air conditioning system 1.

[0018] In order to circulate an appropriate amount of chilled or hot water to each air conditioner 40 in the air conditioning system 1, the chilled or hot water pump differential pressure, which is the differential pressure between the upstream and downstream sides of the chilled or hot water pump 20, must be equal to or greater than the flow path resistance. Here, the flow path resistance is the sum of the piping resistance, which is the resistance of the piping 30, the inlet piping 31, and the outlet piping 32, the resistance of the air conditioner coil (not shown) of each air conditioner 40, and the resistance of each control valve 50. Hereinafter, the sum of the resistance of the air conditioner coil of each air conditioner 40 and the resistance of each control valve 50 for each air conditioner 40 will be referred to as the air conditioner resistance. Hereinafter, the differential pressure required to circulate chilled or hot water against this air conditioner resistance will be referred to as the air conditioner differential pressure.

[0019] In the first model shown in FIG. 2, ten air conditioners 40 are connected in parallel to a chilled / hot water pump 20. A control valve 50 is provided for each air conditioner 40. The air conditioner flow rate ratio, which is the chilled / hot water flow rate that should be circulated through each air conditioner 40 to the design maximum air conditioner flow rate, is shown in the air conditioner 40 as a numerical value excluding percentages. In the following description, when a numerical value is shown that is not limited to the air conditioner flow rate ratio, the numerical value is shown as including an approximate number. In the model shown in FIG. 2, each air conditioner 40 is operating at the design maximum air conditioner flow rate, so the air conditioner flow rate ratio of each air conditioner 40 is 100%, and the air conditioner flow rate ratios of all the air conditioners 40 are uniform. In this model, the outlet side piping 32 connected to each air conditioner 40 is divided into m1 to m 10 The inlet pipes 31 connected to the air conditioners 40 are designated by n1 to n 10 The pipe 30 on which the hot and cold water pump 20 is provided is indicated by the symbol m0.

[0020] In this first model, the pipe length between m0 and m1, the pipe length between m1 and m2...m9 to m 10 The pipe lengths between m0 and n1 are the same, and the pipe lengths between n1 and n2 are the same... 10 The lengths of the piping between the air conditioners 40 and the piping connected thereto are the same. The side closer to the chilled / hot water pump 20 is referred to as the front side, and the side farther from the chilled / hot water pump 20 is referred to as the end side.

[0021] The chilled / hot water pump differential pressure, which is the pressure difference between the upstream and downstream sides of the chilled / hot water pump 20 in the piping 30, is indicated by the symbol Pt. The air conditioner resistance of the air conditioner 40 is indicated by a shaded arrow Ra, and the control valve resistance of the control valve 50 is indicated by a plain arrow Rc. The round-trip resistance of the inlet side piping 31 and the outlet side piping 32, i.e., the piping resistance, is indicated by Rp, and the maximum value of the air conditioner resistance in the air conditioning system 1 is indicated by Rm. The magnitudes of the pressure difference Pt, the air conditioner resistance Ra, the control valve resistance Rc, the piping resistance Rp, and the maximum value Rm are each shown as corresponding to the horizontal length in FIG. 2.

[0022] This first model is a constant differential pressure control, and the m 10 and n of the outlet side piping 32 10 The chilled / hot water pump differential pressure Pt is set so that the air conditioner flow rate ratio of the air conditioners 40 connected to the terminal end is 100% of the maximum designed air conditioner flow rate. Therefore, since the differential pressure of the chilled / hot water supplied to the air conditioners 40 on the front side, which have lower piping resistance than the air conditioners 40 on the terminal end, is excessively large, the control valve 50 is used to provide an appropriate resistance, thereby controlling and adjusting the differential pressure and flow rate of the chilled / hot water.

[0023] Figure 3 is a diagram of a second model for studying the pressure difference of variable flow rate control in the air conditioning system shown in Figure 1. The second model shown in Figure 3 differs from the first model shown in Figure 2 in that not all air conditioners 40 are operating at the maximum designed air conditioner flow rate. Specifically, this is a model for studying a case where the chilled / hot water flow rate ratio of the entire air conditioning system 1 is 50%, and the air conditioner flow rate ratio of each air conditioner 40 is 50%.

[0024] Next, we will consider the piping resistance of the entire air conditioning system in a second model of the air conditioning system 1 shown in Figure 3. In this second model, the chilled / hot water flow rate ratio is set to 50% compared to the air conditioning system 1 of the first model shown in Figure 2, so according to the square law, the piping resistance of the entire air conditioning system 1 of the second model is 25% of the piping resistance Rp of the entire air conditioning system 1 of the first model, or 1 / 4Rp.

[0025] Next, the design maximum air conditioner flow rate of the air conditioner resistance of the air conditioning system will be considered in the second model shown in Figure 3. In this second model air conditioning system 1, the air conditioner flow rates of each air conditioner 40 are the same 50%, so the air conditioner resistance of each air conditioner 40 is the same value. Also, in this second model, the chilled / hot water flow rate ratio is 50% compared to the first model air conditioning system 1 shown in Figure 2, so the air conditioner resistance of this second model is 25% of that of the first air conditioning system 1, or 1 / 4 Rm, according to the square law.

[0026] Here, in the second model air conditioning system 1 shown in Fig. 3, if the chilled / hot water pump 20 is controlled and driven to achieve the same chilled / hot water pump differential pressure Pt as in the first model shown in Fig. 2, as described above, the piping resistance of the entire air conditioning system 1 in the second model is 25% (1 / 4 Rp) of that in the first model, and the air conditioner resistance is 25% (1 / 4 Rm) of that in the first model, so it is necessary to introduce resistance using the control valve 50 to reduce the differential pressure between the upstream and downstream sides of the chilled / hot water pump 20 by 75%. In other words, most of the energy required to apply the chilled / hot water pump differential pressure Pt is consumed by the resistance of the control valve 50, and controlling and driving the chilled / hot water pump 20 in the second model air conditioning system 1 to achieve the same chilled / hot water pump differential pressure Pt as in the first model results in a large energy loss in the air conditioning system 1.

[0027] (Study of energy saving by reducing differential pressure in constant differential pressure control of air conditioning systems) As in the second model described above, when all air conditioners 40 in the air conditioning system 1 operate at less than the maximum design air conditioner flow rate, the chilled / hot water pump 20 can be controlled and driven so that the chilled / hot water pump differential pressure Pt is less than that when the air conditioners 40 operate at the maximum design air conditioner flow rate. Specifically, the chilled / hot water pump 20 can be controlled so that the chilled / hot water pump differential pressure Pt is less than the maximum design air conditioner flow rate and can supply the chilled / hot water flow rate required for the air conditioners 40 operating at the maximum air conditioner flow rate, among the air conditioners 40 included in the air conditioning system 1. This makes it possible to reduce the workload of the chilled / hot water pump 20 without causing a shortage of the chilled / hot water flow rate supplied to the air conditioners 40.

[0028] The theoretical power P of the pump can be obtained from the following equation (1). P=ρgQH / η p η m (1) where Q is the flow rate [m 3 / h], H is the head [m], ρ is the density of the solution [kg / m 3 ], g is acceleration [m / s 2 ], η p is the pump efficiency, η mindicates the efficiency of the engine. Also, the efficiency of the engine η m includes inverter efficiency.

[0029] Although there is a loss due to reduced efficiency compared to the theoretical power P, the theoretical power P is proportional to the product of the differential pressure, which is determined by the flow rate Q and the head H, so in addition to reducing power through variable flow rate, reducing the differential pressure also reduces the pump's workload, realizing energy savings according to the reduction rate. Although variable flow rate control alone reduces the pump's power by only about 50%, it is thought that introducing variable head control could reduce it by a further 75%.

[0030] (Regarding the decision to lower the differential pressure in constant differential pressure control) Next, we consider a means for reducing the chilled / hot water pump differential pressure Pt in constant differential pressure control. To reduce the differential pressure in an air conditioning system just enough, minimum differential pressure variable flow control is a known control method that reduces the differential pressure by controlling the opening of the control valves provided for each air conditioner. However, because minimum differential pressure variable flow control requires knowledge of the opening information of all control valves to control their opening, it has the problem of being difficult to adopt in existing air conditioning systems in existing facilities where control valve opening information is not available.

[0031] On the other hand, if the air supply temperature of each air conditioner 40 shown in FIG. 1 is maintained when the chilled / hot water pump differential pressure Pt is reduced, it can be said that the chilled / hot water flow rate supplied to each air conditioner 40 is sufficient, and that the air conditioning system 1 can be operated with the reduced chilled / hot water pump differential pressure Pt. Therefore, whether the chilled / hot water flow rate is sufficient is determined based on whether the air supply temperature of the air conditioner 40 is maintained within the air supply temperature range required for air conditioning temperature control in that air conditioning system 1, and by reducing the differential pressure within the range in which the chilled / hot water flow rate to the air conditioner 40 is sufficient, it is possible to reduce energy consumption during operation of the air conditioning system 1. In this embodiment, the chilled / hot water pump differential pressure Pt is reduced by this means.

[0032] Next, the operation of the air conditioning system 1 of this embodiment will be described. Figure 4 is a flowchart showing the operation of the air conditioning system 1 of this embodiment. After the air conditioning system 1 starts operation in step S1, during operation of the air conditioning system 1, chilled or hot water flowing out from the heat source 60 is sent out by the chilled or hot water pump 20, circulates through the inlet piping 31, and flows into the air conditioning coil 43 of each air conditioner 40. Each air conditioner 40 sends air taken in from the air intake 41 to the air conditioning coil 43 by the fan 42, and after heating or cooling the air, blows it out from the outlet 44. The chilled or hot water that has circulated through the air conditioning coil 43 flows through the outlet piping 32, passes through the detector 80, and flows into the heat source 60.

[0033] The air outlet sensor 47 detects the air temperature, humidity, and air volume of the air blown from the air outlet 44. The air temperature, humidity, and air volume of the air blown are monitored by an air conditioning load detection unit 82 connected to the air outlet sensor 47.

[0034] The capacity of the air conditioning coil 43 to heat or cool the air taken in by each air conditioner 40 corresponds to the flow rate of hot or cold water flowing into the air conditioning coil 43, and therefore the capacity of the air conditioning coil 43 to heat or cool corresponds to the pressure difference of the air conditioning system 1. First, the cooling operation of the air conditioning system 1 will be described. When the air conditioning system 1 is performing cooling operation, in step S2 the air conditioning load detection unit 82 determines whether the temperature of the air blown out of each air conditioner 40 is being maintained within the blown air temperature range required for air conditioning temperature control.

[0035] If the blower air temperature is maintained within the blower temperature range required for air conditioning temperature control, it is considered that the flow rate of chilled or hot water flowing into the air conditioner coil 43 is sufficient, and the air conditioner 40 has a sufficient cooling capacity to spare. In this case, in step S3, the pump output setting unit 90 sets an output lower than the current output of the chilled or hot water pump 20. The control unit 70 changes the output frequency of the inverter 21 to an output frequency lower than the current output so that the output of the chilled or hot water pump 20 becomes the low output set by the pump output setting unit 90, and operates the motor of the chilled or hot water pump 20 at this output frequency to drive the chilled or hot water pump 20. This reduces the differential pressure of the chilled or hot water generated by the chilled or hot water pump 20.

[0036] On the other hand, if the temperature rises and the air supply temperature is not maintained within the range required for air conditioning temperature control during cooling operation, it is considered that the flow rate of chilled / hot water flowing into the air conditioner coil 43 is insufficient, and the air conditioner 40 does not have sufficient cooling capacity. In this case, in step S4, the pump output setting unit 90 sets a higher output than the current output of the chilled / hot water pump 20. The control unit 70 changes the output frequency of the inverter 21 to a higher output frequency than the current output so that the output of the chilled / hot water pump 20 becomes the high output set by the pump output setting unit 90, and operates the motor of the chilled / hot water pump 20 at this output frequency to drive the chilled / hot water pump 20. This increases the differential pressure of the chilled / hot water generated by the chilled / hot water pump 20. During subsequent cooling operation of the air conditioning system 1, the differential pressure of the chilled / hot water is controlled according to the blowing air temperature in accordance with steps S2 to S4 described above.

[0037] Next, the heating operation of the air conditioning system 1 will be described. After the air conditioning system 1 starts operating in step S1, the air conditioning load detection unit 82 determines in step S2 whether the air supply temperature range required for air conditioning temperature control is being maintained. If the air supply temperature range required for air conditioning temperature control is being maintained, it is considered that the flow rate of chilled or hot water flowing into the air conditioner coil 43 is sufficient and the air conditioner 40 has sufficient heating capacity. In this case, in step S3, the pump output setting unit 90 sets an output lower than the current output of the chilled or hot water pump 20. The control unit 70 changes the output frequency of the inverter 21 to an output frequency lower than the current output so that the output of the chilled or hot water pump 20 becomes the low output set by the pump output setting unit 90, and operates the motor of the chilled or hot water pump 20 at this output frequency to drive the chilled or hot water pump 20. This reduces the differential pressure of the chilled or hot water generated by the chilled or hot water pump 20.

[0038] On the other hand, if the temperature is dropping and not maintained within the range of the blown air temperature required for air conditioning temperature control during heating operation, it is considered that the flow rate of chilled / hot water flowing into the air conditioner coil 43 is insufficient, and the heating capacity of the air conditioner 40 does not have sufficient margin. In this case, in step S4, the pump output setting unit 90 sets a higher output than the current output of the chilled / hot water pump 20. The control unit 70 changes the output frequency of the inverter 21 to a higher output frequency than the current output so that the output of the chilled / hot water pump 20 becomes the high output set by the pump output setting unit 90, and operates the motor of the chilled / hot water pump 20 at this output frequency to drive the chilled / hot water pump 20. This increases the differential pressure of the chilled / hot water generated by the chilled / hot water pump 20. During subsequent operation of the air conditioning system 1, the differential pressure of the chilled / hot water is controlled according to the blown air temperature in accordance with steps S2 to S4 described above.

[0039] As described above, the temperature of the air blown from the air conditioner 40 is monitored during heating / cooling operation of the air conditioning system 1, and it is determined whether the temperature of the air blown from the air conditioner 40 is within the air blowing temperature range required for air conditioning temperature control or outside the air blowing temperature range. Depending on the determination result, the output frequency of the inverter 21 of the chilled / hot water pump 20 is controlled to control the differential pressure of the chilled / hot water delivered by the chilled / hot water pump 20, thereby reducing the output of the chilled / hot water pump 20 and reducing the energy consumption of the air conditioning system 1 while maintaining the capacity of each air conditioner 40 within an appropriate range.

[0040] Furthermore, when the chilled / hot water pump 20, which is the transport power for transporting chilled / hot water, is driven, the heat generated by driving the chilled / hot water pump 20 warms the chilled / hot water, which places a thermal load on the heat source 60, which is the source of cold heat during cooling operation. Therefore, by lowering the output of the chilled / hot water pump 20, the thermal load on the heat source 60 can be reduced, further reducing the energy consumption of the air conditioning system 1.

[0041] In setting the output frequency of the inverter 21, it is generally preferable to set the lower limit to 60% of the rated frequency of the motor of the chilled / hot water pump 20, but if it is confirmed that no problems will occur in the operation of the chilled / hot water pump 20 and its motor, the rated frequency of the motor of the chilled / hot water pump 20 may be set to less than 60%.

[0042] Furthermore, as in step S3 or step S4, when the output frequency of inverter 21 is changed to decrease or increase the differential pressure of chilled or hot water pump 20, the amount of decrease or increase in the differential pressure per time may be set appropriately depending on the operating characteristics of air conditioning system 1 and the heating and cooling performance required by the user. For example, if air conditioning system 1 is used in a facility such as a hospital where malfunctions in the air conditioning system are not permitted 24 hours a day, the amount of decrease or increase in the differential pressure of chilled or hot water pump 20 per time can be made smaller to reduce the possibility of malfunctions such as insufficient cooling or heating capacity occurring after the differential pressure of chilled or hot water pump 20 is decreased or increased.

[0043] Furthermore, the time until the air conditioning load detection unit 82 determines in step S2 whether the blower air temperature range required for air conditioning temperature control is maintained after changing the output frequency of inverter 21 to decrease or increase the differential pressure of chilled or hot water pump 20 in step S3 or step S4 may be set appropriately depending on the operating characteristics of air conditioning system 1 and the cooling / heating performance required by the user. For example, by setting a longer time until the blower air temperature is determined in step S2 after performing step S3 or step S4, it is possible to verify whether the effect of the change in differential pressure appears after a long time has passed since the differential pressure of chilled or hot water pump 20 was decreased or increased.

[0044] Constant differential pressure control is often used as a means of controlling the variable flow rate of hot and cold water in air conditioning systems installed in existing facilities, so the control method for air conditioning system 1 that implements constant differential pressure control as in this embodiment can be used without modifying or replacing the air conditioning system of an existing facility, and can improve the energy efficiency of the air conditioning system.

[0045] In this way, the air conditioning system 1 performs variable flow control of chilled or hot water using constant differential pressure control, and includes a heat source 60 that heats or cools chilled or hot water, a plurality of air conditioners 40 through which chilled or hot water flows, a chilled or hot water pump 20 that supplies chilled or hot water to each air conditioner 40, piping 30 that connects the heat source 60, the chilled or hot water pump 20, and each air conditioner 40, an outlet sensor 47 that detects the air supply temperature of each air conditioner 40, a pump output setting unit 90 that sets the chilled or hot water pump output of the chilled or hot water pump 20, and a control unit 70 that operates the chilled or hot water pump 20 at the chilled or hot water pump output set by the pump output setting unit 90.The pump output setting unit 90 sets the chilled or hot water pump output of the chilled or hot water pump 20 so that the air supply temperature of each air conditioner 40 detected by the outlet sensor 47 is within the air supply temperature range required for air conditioning temperature control, thereby reducing the differential pressure in constant differential pressure control and reducing the energy consumption of the air conditioning system 1.

[0046] In addition, the pump output setting unit 90 sets the output of the chilled / hot water pump 20 so as to reduce the differential pressure, which is the difference between the pressure of the chilled / hot water discharged from the chilled / hot water pump 20 and the pressure of the chilled / hot water flowing into the chilled / hot water pump 20, when the discharge air temperature of each air conditioner 40 is within the discharge air temperature range, and sets the output of the chilled / hot water pump 20 so as to increase the differential pressure when the discharge air temperature of each air conditioner 40 is outside the discharge air temperature range.Therefore, the differential pressure can be controlled in accordance with the air conditioning capacity of each air conditioner, thereby reducing the energy consumption of the air conditioning system 1.

[0047] Furthermore, when the air discharge temperature of each air conditioner 40 is equal to or higher than a predetermined value relative to the upper limit of the air discharge temperature range or is equal to or lower than a predetermined value relative to the lower limit of the air discharge temperature range, the pump output setting unit 90 sets the output of the chilled / hot water pump 20 so that the differential pressure becomes a predetermined differential pressure. Therefore, when the operating state of each air conditioner 40 deviates significantly from a desirable state, the differential pressure is detected and controlled to become the predetermined differential pressure, and the air discharge temperature of each air conditioner 40 can be quickly brought into the air discharge temperature range.

[0048] Furthermore, a control method for an air conditioning system 1 in this embodiment is a control method for an air conditioning system including a heat source 60 that heats or cools chilled or hot water, a plurality of air conditioners 40 through which chilled or hot water flows, a chilled or hot water pump 20 that supplies chilled or hot water to each of the air conditioners 40, piping 30 that connects the heat source 60, the chilled or hot water pump 20, and each of the air conditioners 40, an outlet sensor 47 that detects the temperature of air sent from each of the air conditioners 40, a pump output setting unit 90 that sets the chilled or hot water pump output of the chilled or hot water pump 20, and a control unit 70 that controls the chilled or hot water pump 20 with the chilled or hot water pump output set by the pump output setting unit 90, The system includes the steps of detecting the discharge air temperature of each air conditioner 40, and when the discharge air temperature of each air conditioner 40 detected by the outlet sensor 47 is within the discharge air temperature range required for air conditioning temperature control, the pump output setting unit 90 sets the output of the chilled / hot water pump 20 so as to reduce the differential pressure, and when the discharge air temperature of each air conditioner 40 is outside the discharge air temperature range required for air conditioning temperature control, the pump output setting unit 90 sets the output of the chilled / hot water pump 20 so as to increase the differential pressure, thereby reducing the differential pressure in constant differential pressure control and reducing the energy consumption of the air conditioning system 1.

[0049] In the air conditioning system 1 according to this embodiment, if the blown air temperature deviates from the blown air temperature range by a predetermined value or more, a chilled / hot water pump differential pressure, which is the differential pressure between the upstream and downstream sides of the chilled / hot water pump 20, may be determined based on the detection results of a flow detection unit (not shown) provided in each control valve 50 that measures the differential pressure inside the control valve 50 to detect the flow rate of chilled / hot water flowing through the control valve 50. This allows the blown air temperature of each air conditioner 40 to quickly fall within the blown air temperature range when the blown air temperature deviates significantly from the blown air temperature range.

[0050] Furthermore, in the air conditioning system 1 according to the embodiment of the present invention, the air supply temperature range required for air conditioning temperature control may be a pre-set air supply temperature range based on any conditions such as the configuration and usage environment of the air conditioning system 1, the usage environment of each air conditioner 40, etc. [Explanation of symbols]

[0051] 20 chilled / hot water pump, 30 piping, 40 air conditioner, 41 air intake (inlet / outlet), 42 outlet (inlet / outlet), 47 outlet sensor (air supply temperature detection unit), 60 heat source, 70 control unit, 80 detector (detection unit), 81 outdoor air specific enthalpy detection unit (detection unit), 90 pump output setting unit.

Claims

1. A heat source for heating or cooling cold or hot water; a plurality of air conditioners through which the hot and cold water circulates; a cold / hot water pump for supplying the cold / hot water to each of the air conditioners; piping that connects the heat source, the hot and cold water pump, and each of the air conditioners; a blowing air temperature detection unit that detects the blowing air temperature of each of the air conditioners; a pump output setting unit that sets the chilled / hot water pump output of the chilled / hot water pump; a control unit that operates the chilled / hot water pump at the chilled / hot water pump output set by the pump output setting unit; Equipped with The pump output setting unit sets the chilled / heated water pump output of the chilled / heated water pump so that the blowing air temperature of each air conditioner detected by the blowing air temperature detection unit is within the blowing air temperature range required for air conditioning temperature control.

2. The air conditioning system of claim 1, wherein the pump output setting unit sets the chilled / hot water pump output so as to reduce the differential pressure, which is the difference between the pressure of the chilled / hot water discharged from the chilled / hot water pump and the pressure of the chilled / hot water flowing into the chilled / hot water pump, when the supply air temperature of each air conditioner is within the supply air temperature range, and sets the chilled / hot water pump output so as to increase the differential pressure when the supply air temperature of each air conditioner is outside the supply air temperature range.

3. 3. The air conditioning system of claim 2, wherein the pump output setting unit sets the chilled / hot water pump output so that the differential pressure becomes a predetermined specified differential pressure when the blowing air temperature of each air conditioner is equal to or higher than a predetermined value relative to an upper limit of the blowing air temperature range or is equal to or lower than a predetermined value relative to a lower limit of the blowing air temperature range.

4. A heat source for heating or cooling cold or hot water; a plurality of air conditioners through which the hot and cold water circulates; a cold / hot water pump for supplying the cold / hot water to each of the air conditioners; piping that connects the heat source, the hot and cold water pump, and each of the air conditioners; a blowing air temperature detection unit that detects the blowing air temperature of each of the air conditioners; a pump output setting unit that sets the chilled / hot water pump output of the chilled / hot water pump; a control unit that controls the chilled / hot water pump at the chilled / hot water pump output set by the pump output setting unit; A control method for an air conditioning system comprising: a step in which the blown air temperature detection unit detects the blown air temperature of each of the air conditioners; a pump output setting unit setting the chilled / hot water pump output so as to reduce the differential pressure when the discharge air temperature of each air conditioner detected by the discharge air temperature detection unit is within a discharge air temperature range required for air conditioning temperature control, and a pump output setting unit setting the chilled / hot water pump output so as to increase the differential pressure when the discharge air temperature of each air conditioner is outside the discharge air temperature range required for air conditioning temperature control.

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