Air conditioning system

Abstract

To autonomously control a heat source machine with a simpler structure while effectively collecting exhaust heat of a plurality of load devices.SOLUTION: An air conditioning system (1) comprises a heat source machine (10), a low-temperature side pipe (31), a high-temperature side pipe (32), a plurality of load devices (20), temperature sensors (16 and 17) for detecting heat source water temperatures around a water heat exchanger (15) of the heat source machine (10), and a control device (100). The plurality of load devices (20) each take high-temperature heat source water from the high-temperature side pipe (32) at the time of heating, discharge the heat source water to the low-temperature side pipe (31) after using it for the heating, take low-temperature heat source water from the low-temperature side pipe (31) at the time of cooling, and discharge the heat source water to the high-temperature side pipe (32) after using it for the cooling. The control device (100) controls the heat source machine (10) in one operation state out of a heating operation state, a cooling operation state, and a stop state on the basis of detection results of the temperature sensors (16 and 17).SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an air conditioning system for heating and cooling multiple spaces. [Background technology]

[0002] In the past, air conditioning systems that cooled and heated multiple spaces typically transported heat from a primary refrigerant directly to the multiple spaces. However, in recent years, with the aim of reducing the amount of primary refrigerant used, which can contribute to global warming, so-called chiller systems have been reconsidered. These systems transfer the heat from the primary refrigerant to a safer secondary refrigerant and then transport it indirectly to the multiple spaces, rather than directly transporting the heat from the primary refrigerant to the multiple spaces.

[0003] For example, Japanese Patent Laid-Open Publication No. 2007-315621 (Patent Document 1) discloses an air conditioning system that transfers heat from a first refrigerant to heat-source water, which is a secondary refrigerant, and then transports the heat to multiple water-cooled heat pumps. This air conditioning system includes a heat source machine that transfers heat from the first refrigerant to heat-source water, which is a secondary refrigerant, a low-temperature side pipe to which low-temperature heat-source water is supplied from the heat source machine, a high-temperature side pipe to which high-temperature heat-source water is supplied from the heat source machine, multiple water-cooled heat pumps connected in parallel between the high-temperature side pipe and the low-temperature side pipe, and a control device that controls the operating state of the heat source machine.

[0004] The heat source machine is equipped with a cold heat source device and a cold heat pump for cooling the heat source water in the high-temperature side piping and supplying it to the low-temperature side piping, and a hot heat source device and a hot heat pump for heating the heat source water in the low-temperature side piping and supplying it to the high-temperature side piping.

[0005] When the operation state of the plurality of water-cooled heat pumps is full cooling or mainly cooling, the control device operates the cold heat pump of the heat source machine to cool the heat source water in the high-temperature side pipe with the cold heat source equipment and supply it to the low-temperature side pipe.On the other hand, when the operation state of the plurality of water-cooled heat pumps is full heating or mainly heating, the control device operates the hot heat pump of the heat source machine to heat the heat source water in the low-temperature side pipe with the hot heat source equipment and supply it to the high-temperature side pipe. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-315621 Summary of the Invention [Problem to be solved by the invention]

[0007] In the air conditioning system disclosed in JP 2007-315621 A, the heat source unit requires two water pumps (a cold heat pump and a hot heat pump) to circulate the heat source water, which can result in an increase in the number of components of the heat source unit.

[0008] Furthermore, in the air conditioning system disclosed in JP 2007-315621 A, whether to operate the cold heat pump or the hot heat pump of the heat source machine is determined based on the operating status of multiple load devices (water-cooled heat pumps). Therefore, in order to control the heat source machine, it is necessary to monitor the operating status of all of the multiple load devices, and the heat source machine cannot be controlled autonomously.

[0009] Furthermore, in the air conditioning system disclosed in JP 2007-315621 A, regardless of whether the multiple water-cooled heat pumps are operating in full cooling, cooling-dominated, full heating, or heating-dominated mode, either the cold heat pump or the hot heat pump of the heat source unit is always operating. Therefore, it is possible that a situation may arise in which the cold heat pump or the hot heat pump is operated unnecessarily, and it is assumed that the exhaust heat of the load device cannot be effectively recovered.

[0010] The present invention has been made to solve the above-mentioned problems, and its purpose is to autonomously control a heat source machine with a simpler configuration while effectively recovering exhaust heat from multiple load devices. [Means for solving the problem]

[0011] An air conditioning system according to the present disclosure is an air conditioning system for heating and cooling multiple spaces, and includes: a first pipe through which heat-source water flows; a second pipe connected to the first pipe and through which heat-source water with a temperature higher than that of the heat-source water in the first pipe flows; multiple load devices each connected to the first pipe and the second pipe for individually heating and cooling the multiple spaces; and a heat source unit having a refrigerant circuit including a water heat exchanger that exchanges heat between the heat-source water flowing through the connecting portion between the first pipe and the second pipe and a primary refrigerant. When heating a space, each of the multiple load devices takes in heat-source water from the second pipe, heats the space using the heat-source water taken in from the second pipe, and discharges the heat-source water after using it to heat the space back into the first pipe; and when cooling a space, takes in heat-source water from the first pipe, cools the space using the heat-source water taken in from the first pipe, and discharges the heat-source water after using it to cool the space back into the second pipe. The heat source machine is configured to be able to switch its operating state between a heating operation state in which a primary refrigerant is circulated to heat the heat source water in the water heat exchanger, a cooling operation state in which the primary refrigerant is circulated to cool the heat source water in the water heat exchanger, and a stop state in which the circulation of the primary refrigerant is stopped. The air conditioning system further includes a detection device that detects the state of the heat source water in or around the water heat exchanger, and a control device that controls the heat source machine to one of the heating operation state, cooling operation state, and stop state based on the detection result of the detection device. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to autonomously control a heat source machine with a simpler configuration while effectively recovering exhaust heat from a plurality of load devices. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram (part 1) schematically illustrating an example of the overall configuration of an air conditioning system. [Figure 2] FIG. 2 is a diagram showing the cooling operation state of the heat source machine. [Figure 3] FIG. 4 is a diagram showing the heating operation state of the heat source machine. [Figure 4] FIG. 10 is a diagram showing a state in which the heat source machine is stopped. [Figure 5]FIG. 10 is a diagram showing the flow of heat source water when the operating states of a plurality of load devices are in a full cooling state. [Figure 6] FIG. 10 is a diagram showing the flow of heat source water when the operating states of a plurality of load devices are in a full heating state. [Figure 7] FIG. 10 is a diagram showing the flow of heat-source water when the operating states of a plurality of load devices are in a cooling-dominated state. [Figure 8] FIG. 10 is a diagram showing the flow of heat-source water when the operating states of a plurality of load devices are in a heating-dominated state. [Figure 9] 10 is a diagram showing a heat source water temperature TH detected by a high temperature sensor and a heat source water temperature TL detected by a low temperature sensor, and the operating state of a heat source machine controlled based on the heat source water temperature TH and the heat source water temperature TL. FIG. [Figure 10] 10 is a flowchart (part 1) illustrating an example of a processing procedure of the control device. [Figure 11] FIG. 2 is a diagram schematically illustrating the structure of a four-way valve. [Figure 12] FIG. 2 is a diagram (part 2) schematically illustrating an example of the overall configuration of an air conditioning system. [Figure 13] 10 is a flowchart (part 2) illustrating an example of a processing procedure of the control device. DETAILED DESCRIPTION OF THE INVENTION

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals and their description will not be repeated.

[0015] FIG. 1 is a diagram schematically illustrating an example of the overall configuration of an air conditioning system 1 according to this embodiment. The air conditioning system 1 is a so-called chiller system that transfers heat from a primary refrigerant such as chlorofluorocarbon, carbon dioxide, or propane to a secondary refrigerant different from the primary refrigerant, and then indirectly transports the heat to multiple spaces. Below, an example in which water is used as the secondary refrigerant will be described. Hereinafter, the water used as the secondary refrigerant will also be referred to as "heat source water."

[0016] The air conditioning system 1 includes a heat source unit 10, a low-temperature side pipe (first pipe) 31 through which low-temperature heat source water flows, a high-temperature side pipe (second pipe) 32 through which high-temperature heat source water flows, a plurality of load devices 20, and a control device 100. Note that while Fig. 1 shows an example in which two load devices 20A and 20B are arranged as the plurality of load devices 20, the number of load devices 20 is not limited to two and may be three or more.

[0017] The heat source unit 10 has a primary refrigerant circuit through which a primary refrigerant circulates. The primary refrigerant circuit is configured by connecting a compressor 11, a four-way valve 12, an air heat exchanger 13, a pressure reducing device 14, and a water heat exchanger 15 with refrigerant piping. The water heat exchanger 15 is configured to exchange heat between the primary refrigerant and heat-source water flowing through the connecting portion between the low-temperature side piping 31 and the high-temperature side piping 32.

[0018] The operating state of the heat source unit 10 can be switched between a heating operation state in which the primary refrigerant is circulated to heat the heat source water in the water heat exchanger 15, a cooling operation state in which the primary refrigerant is circulated to cool the heat source water in the water heat exchanger 15, and an operation stop state in which the circulation of the primary refrigerant is stopped.

[0019] Fig. 2 is a diagram showing the cooling operation state of the heat source unit 10. As shown in Fig. 2, in the cooling operation state, the compressor 11 is operated, and the four-way valve 12 is controlled to a cooling state in which the primary refrigerant is circulated through the compressor 11, the air heat exchanger 13, the pressure reducing device 14, and the water heat exchanger 15 in this order. As a result, the heat source water is cooled by the primary refrigerant in the water heat exchanger 15.

[0020] Fig. 3 is a diagram showing the heating operation state of the heat source unit 10. As shown in Fig. 3, in the heating operation state, the compressor 11 is operated, and the four-way valve 12 is controlled to a heating state in which the primary refrigerant is circulated through the compressor 11, the water heat exchanger 15, the pressure reducing device 14, and the air heat exchanger 13 in this order. As a result, the heat source water is heated by the primary refrigerant in the water heat exchanger 15.

[0021] Fig. 4 is a diagram showing the operation stop state of the heat source device 10. As shown in Fig. 4, in the operation stop state, the compressor 11 is stopped, thereby stopping the flow of the primary refrigerant.

[0022] Returning to Fig. 1, the heat source machine 10 further includes a low-temperature sensor (first temperature sensor) 16 and a high-temperature sensor (second temperature sensor) 17, each of which detects the temperature of the heat source water around the water heat exchanger 15. The low-temperature sensor 16 detects the temperature of the heat source water in the low-temperature side piping 31 around the water heat exchanger 15 (hereinafter also referred to as "heat source water temperature TL"). The high-temperature sensor 17 detects the temperature of the heat source water in the high-temperature side piping 32 around the water heat exchanger 15 (hereinafter also referred to as "heat source water temperature TH").

[0023] 1 shows an example in which the low-temperature sensor 16 is disposed inside the heat source machine 10, the low-temperature sensor 16 may be disposed outside the heat source machine 10 as long as it is disposed in the vicinity of the water heat exchanger 15 in the low-temperature side piping 31. Here, the vicinity of the water heat exchanger 15 in the low-temperature side piping 31 is the portion in the low-temperature side piping 31 from the connection with the water heat exchanger 15 to the connection 31a with the load device 20A that is closest to the heat source machine 10.

[0024] 1 shows an example in which high-temperature sensor 17 is disposed inside heat source machine 10, high-temperature sensor 17 may be disposed outside heat source machine 10 as long as it is located in the vicinity of water heat exchanger 15 in high-temperature side piping 32. The vicinity of water heat exchanger 15 in high-temperature side piping 32 is the portion in high-temperature side piping 32 from the connection with water heat exchanger 15 to connection 32a with load device 20A that is closest to heat source machine 10.

[0025] The low-temperature side pipe 31 and the high-temperature side pipe 32 are connected inside the water heat exchanger 15. The water heat exchanger 15 exchanges heat between the heat source water flowing through the connecting portion between the low-temperature side pipe 31 and the high-temperature side pipe 32 and the primary refrigerant.

[0026] The control device 100 includes a CPU (Central Processing Unit), a storage device, an input / output buffer, etc. (none of which are shown), and controls the operation of the compressor 11 in the heat source machine 10, the state of the four-way valve 12, etc., based on the detection results of the low temperature sensor 16 and the high temperature sensor 17. The control of the control device 100 is not limited to software processing, but can also be processed by dedicated hardware (electronic circuitry). Note that while FIG. 1 shows an example in which the control device 100 is disposed outside the heat source machine 10, the location where the control device 100 is disposed is not particularly limited, and the control device 100 may be disposed inside the heat source machine 10, for example.

[0027] The multiple load devices 20 are arranged in multiple spaces, respectively, and individually heat and cool the multiple spaces. The multiple load devices 20 are connected in parallel with one another between low-temperature side piping 31 and high-temperature side piping 32. In the example shown in Fig. 1, load device 20A is arranged between connection portion 31a of low-temperature side piping 31 and connection portion 32a of high-temperature side piping 32, and load device 20B is arranged between end portion 31b of low-temperature side piping 31 and end portion 32b of high-temperature side piping 32. The low-temperature side piping 31, high-temperature side piping 32, and the multiple load devices 20 (20A, 20B) form a secondary refrigerant circuit that circulates heat source water.

[0028] When heating a target space, each of the multiple load devices 20 takes in high-temperature heat source water from the high-temperature side piping 32, heats the target space with the high-temperature heat source water, and discharges the low-temperature heat source water after being used for heating to the low-temperature side piping 31. On the other hand, when cooling a target space, each of the multiple load devices 20 takes in low-temperature heat source water from the low-temperature side piping 31, cools the target space with the low-temperature heat source water, and discharges the high-temperature heat source water after being used for cooling to the high-temperature side piping 32.

[0029] Specifically, each of the multiple load devices 20 includes a water-cooled heat pump 21 that exchanges heat between heat-source water and the air in the target space, a four-way valve (direction switching device) 22 that switches the flow direction of the heat-source water, a variable flow pump 23 that can adjust the flow rate of the heat-source water, and an on-off valve 24 that shuts off the flow of the heat-source water. When the variable flow pump 23 operates with the on-off valve 24 open, a flow of heat-source water is generated in a fixed direction (the direction of the triangle, from right to left in FIG. 1 ). During cooling operation of the load device 20, the heat-source water taken in from the low-temperature side piping 31 flows through the four-way valve 22, the variable flow pump 23, the supply-side piping 33, the water-cooled heat pump 21, the discharge-side piping 34, and the four-way valve 22 in that order, before being discharged into the high-temperature side piping 32. During heating operation of the load devices 20, the heat source water taken in from the high-temperature side pipe 32 flows in this order through the four-way valve 22, the variable flow pump 23, the supply side pipe 33, the water-cooled heat pump 21, the discharge side pipe 34, and the four-way valve 22, before being discharged into the low-temperature side pipe 31. When each load device 20 is stopped, the on-off valve 24 of that load device 20 is closed, thereby blocking the flow of heat source water to that load device 20.

[0030] Next, the correspondence between the operating states of the plurality of load devices 20 and the flow of heat-source water will be described.

[0031] FIG. 5 illustrates the flow of heat-source water when the operating state of multiple load devices 20 is in a full cooling state. The full cooling state is a state in which all load devices 20 are operating in cooling mode. In the full cooling state, as shown in FIG. 5, the variable flow pumps 23A and 23B of each load device 20 operate to return the heat-source water used for cooling in each load device 20 to the high-temperature side pipe 32, the water heat exchanger 15, and the low-temperature side pipe 31, in that order, before returning to each load device 20 and being used for cooling in each load device 20. That is, in the full cooling state, all of the high-temperature heat-source water used for cooling in the load devices 20A and 20B is returned to the water heat exchanger 15 via the high-temperature side pipe 32, causing the temperature of the heat-source water in the high-temperature side pipe 32 around the water heat exchanger 15 to increase quite rapidly. Therefore, in the full cooling state, it is desirable to operate the heat source unit 10 in cooling mode and cool the heat-source water in the water heat exchanger 15. In this way, low-temperature heat source water can be supplied to each load device 20.

[0032] FIG. 6 illustrates the flow of heat-source water when the operating state of multiple load devices 20 is in full heating mode. Full heating mode refers to a state in which all load devices 20 are operating in heating mode. In full heating mode, as shown in FIG. 6, the variable flow pumps 23A and 23B of each load device 20 operate to return the heat-source water used for heating in each load device 20 to the load device 20 via the low-temperature side pipe 31, the water heat exchanger 15, and the high-temperature side pipe 32, in that order, before returning to the load device 20 for use in heating in each load device 20. That is, in full heating mode, all of the low-temperature heat-source water used for heating in the load devices 20A and 20B is returned to the water heat exchanger 15 via the low-temperature side pipe 31, causing the temperature of the heat-source water in the low-temperature side pipe 31 around the water heat exchanger 15 to drop quite rapidly. Therefore, in full heating mode, it is desirable to operate the heat source unit 10 in heating mode and heat the heat-source water in the water heat exchanger 15. This allows high-temperature heat-source water to be supplied to each load device 20.

[0033] 7 is a diagram showing the flow of heat-source water when the operating state of the multiple load devices 20 is a cooling-dominated state. The cooling-dominated state is a state in which some of the multiple load devices 20 are operating in cooling mode and the rest are operating in heating mode, and the flow rate of the heat-source water used for the cooling mode is greater than the flow rate of the heat-source water used for the heating mode.

[0034] In the cooling-dominated state, as shown in Figure 7, the high-temperature heat source water after being used for cooling by the load device 20A operating in cooling mode is branched at the connection part 32a of the high-temperature side piping 32 into heat source water heading toward the water heat exchanger 15 and heat source water heading toward the load device 20B operating in heating mode, and then merges at the connection part 31a of the low-temperature side piping 31 and is returned to the load device 20A.

[0035] That is, in the cooling-dominated state, only a portion of the high-temperature heat-source water after being used for cooling in the load device 20A is returned to the water heat exchanger 15 via the high-temperature side piping 32. Therefore, the temperature of the heat-source water in the high-temperature side piping 32 around the water heat exchanger 15 rises more slowly than in the full cooling state. Also, in the cooling-dominated state, the remainder of the high-temperature heat-source water after being used for cooling in the load device 20A is supplied to the load device 20B, which is operating in heating mode, without passing through the high-temperature side piping 32. Therefore, a portion of the exhaust heat (hot heat) of the heat-source water after being used for cooling in the load device 20A can be recovered as heat for heating the load device 20B.

[0036] 8 is a diagram showing the flow of heat-source water when the operating state of the multiple load devices 20 is a heating-dominated state. The heating-dominated state is a state in which some of the multiple load devices 20 are operating in heating mode and the remaining are operating in cooling mode, and the flow rate of the heat-source water used for the heating mode is greater than the flow rate of the heat-source water used for the cooling mode.

[0037] In the heating-dominated state, as shown in Figure 8, the low-temperature heat source water after being used for heating by the load device 20A operating in heating mode is branched at the connection part 31a of the low-temperature side piping 31 into heat source water heading toward the water heat exchanger 15 and heat source water heading toward the load device 20B operating in cooling mode, and then merges at the connection part 32a of the high-temperature side piping 32 and is returned to the load device 20A.

[0038] That is, in the heating-dominated state, only a portion of the low-temperature heat-source water after being used for heating in the load device 20A is returned to the water heat exchanger 15 via the low-temperature side piping 31. Therefore, the temperature of the heat-source water in the low-temperature side piping 31 around the water heat exchanger 15 drops more slowly than in the full heating state. Also, in the heating-dominated state, the remainder of the low-temperature heat-source water after being used for heating in the load device 20A is supplied to the load device 20B, which is operating in cooling mode, without passing through the low-temperature side piping 31. Therefore, a portion of the exhaust heat (cold heat) of the heat-source water after being used for heating in the load device 20A can be recovered as heat for cooling the load device 20B.

[0039] In consideration of the correspondence between the operating states of the multiple load devices 20 and the flow of heat source water shown in Figures 5 to 8 above, the control device 100 of this embodiment autonomously controls the heat source machine 10 based on the temperature of the heat source water around the water heat exchanger 15 (detection results of the low temperature sensor 16 and the high temperature sensor 17) without monitoring the operating states of the multiple load devices 20.

[0040] Figure 9 is a diagram showing the heat source water temperature TH detected by the high temperature sensor 17 and the heat source water temperature TL detected by the low temperature sensor 16, and the operating state of the heat source unit 10 controlled based on the heat source water temperature TH and the heat source water temperature TL.

[0041] When the heat source machine 10 stops while the plurality of load devices 20 are in the full cooling operation state or the cooling-dominant state, the heat source water is not cooled by the water heat exchanger 15, so the heat source water temperature TH detected by the high-temperature sensor 17 rises. Therefore, when the heat source water temperature TH exceeds a predetermined high-temperature threshold value Thi during the stop of the heat source machine 10, the control device 100 switches the heat source machine 10 to the cooling operation state. As a result, since the heat source water is cooled by the water heat exchanger 15, it is possible to suppress the heat source water from becoming excessively high in temperature and supply low-temperature heat source water to the load devices 20 that are in the cooling operation.

[0042] After the heat source machine 10 is switched to the cooling operation state, the heat source water is cooled by the water heat exchanger 15. At this time, when the plurality of load devices 20 are in the cooling-dominant state and the heat balance is balanced among the plurality of load devices 20, the heat source water temperature TH may decrease due to the cooling by the water heat exchanger 15. Therefore, when the heat source water temperature TH falls below a temperature that is lower than the high-temperature threshold value Thi by a reference value ΔH during the cooling operation of the heat source machine 10 (that is, when TH < Thi - ΔH), the control device 100 stops the heat source machine 10 again. As a result, it is possible to suppress unnecessarily operating the heat source machine 10 until the heat balance is balanced among the plurality of load devices 20. As a result, it is possible to effectively recover the waste heat (warm heat) of the load devices 20 that are in the cooling operation and improve the energy efficiency.

[0043] On the other hand, when the heat source machine 10 stops while the plurality of load devices 20 are in the full heating operation state or the heating-dominant state, the heat source water is not heated by the water heat exchanger 15, so the heat source water temperature TL detected by the low-temperature sensor 16 decreases. Therefore, when the heat source water temperature TL falls below a predetermined low-temperature threshold value Tlow during the stop of the heat source machine 10, the control device 100 switches the heat source machine 10 to the heating operation state. As a result, since the heat source water is heated by the water heat exchanger 15, it is possible to suppress the heat source water from becoming excessively low in temperature and supply high-temperature heat source water to the load devices 20 that are in the heating operation.

[0044] After the heat source machine 10 is switched to the heating operation state, the heat source water is heated by the water heat exchanger 15. At this time, if the plurality of load devices 20 are in a heating-dominated state and the heat balance is balanced among the plurality of load devices 20, the heat source water temperature TL may rise due to heating by the water heat exchanger 15. Therefore, if the heat source water temperature TL exceeds a temperature that is higher than the low temperature threshold value Tlow by a reference value ΔL during the heating operation of the heat source machine 10 (i.e., if TL > Tlow + ΔL), the control device 100 stops the heat source machine 10 again. This prevents the heat source machine 10 from being operated unnecessarily even when the heat balance is balanced among the plurality of load devices 20. As a result, the exhaust heat (cold heat) of the load devices 20 in the heating operation can be effectively recovered, improving energy conservation.

[0045] Note that adjusting the heat source water temperature to the temperature required for air conditioning of the target space in the load device 20 does not necessarily have to be performed by the heat source device 10; it can be performed by the water-cooled heat pump 21 of the load device 20. Therefore, the heat source device 10 can limit the heat source water temperature to the so-called normal temperature range (approximately 20 to 25°C), while the water-cooled heat pump 21 can control the heat source water temperature to the required temperature. This can minimize the operating pressure difference between the compressors in both the heat source device 10 and the load device 20, thereby improving operational efficiency. From this perspective, the values ​​of the high-temperature threshold Thi and the low-temperature threshold Tlow described above may be set to values ​​within the normal temperature range. Note that the normal temperature range is a comfortable temperature in both the cooling and heating seasons, so it can be used not only as input to the water-cooled heat pump 21 but also for radiant air conditioning.

[0046] The values ​​of the high temperature threshold value Thi and the low temperature threshold value Tlow may also be set arbitrarily by the user managing the air conditioning system 1. For example, if the air conditioning system 1 includes many load devices 20 that operate in heating mode at all times, such as hot water heaters, the heat source water temperature can be set higher, and if the air conditioning system 1 includes many load devices 20 that operate in cooling mode at all times, such as server room air conditioners, the heat source water temperature can be set lower.In this way, if it is possible to predict which of the cooling and heating loads is likely to be greater when cooling and heating are used together, the workload of the load devices 20 can be reduced by fine-tuning the values ​​of the high temperature threshold value Thi and the low temperature threshold value Tlow in advance.

[0047] The high temperature threshold value Thi and the low temperature threshold value Tlow may be variable values ​​that are automatically adjusted based on the history of the heat source water temperature relative to the ratio of the cooling load to the heating / cooling load.

[0048] 10 is a flowchart showing an example of a processing procedure executed by the control device 100 when controlling the heat source machine 10. This flowchart is repeatedly executed every time a predetermined condition is met (for example, every predetermined period).

[0049] First, the control device 100 determines whether the operating state of the heat source unit 10 is a cooling operation state, a heating operation state, or a stopped state (step S10).

[0050] [Control when the heat source device 10 is stopped] When the heat source machine 10 is in a stopped state ("Stopped" in step S10), the control device 100 determines whether the heat source water temperature TL detected by the low temperature sensor 16 is lower than the above-mentioned low temperature threshold value Tlow (step S30).

[0051] When the heat-source water temperature TL is lower than the low-temperature threshold value Tlow, it is assumed that the multiple load devices 20 are in a full heating operation state or a heating-dominant state, and the heat balance between the multiple load devices 20 is not balanced, so that heating of the heat-source water is necessary. Therefore, when the heat-source water temperature TL is lower than the low-temperature threshold value Tlow (YES in step S30), the control device 100 changes the operating state of the heat source device 10 to the heating operation state shown in Fig. 3 above (step S70). As a result, the operating state of the heat source device 10 is switched from the stopped state to the heating operation state, and the heat-source water is heated by the heat source device 10.

[0052] If the heat source water temperature TL is higher than the low temperature threshold Tlow (NO in step S30), the control device 100 determines whether the heat source water temperature TH detected by the high temperature sensor 17 is higher than the high temperature threshold Thi (step S31).

[0053] When the heat-source water temperature TH is higher than the high-temperature threshold value Thi, it is assumed that the multiple load devices 20 are in a full cooling operation state or a cooling-dominant state, and the heat balance between the multiple load devices 20 is not balanced, so that cooling of the heat-source water is necessary. Therefore, when the heat-source water temperature TH is higher than the high-temperature threshold value Thi (YES in step S31), the control device 100 changes the operating state of the heat source device 10 to a cooling operation state (step S50). As a result, the operating state of the heat source device 10 is switched from a stopped state to a cooling operation state, and the heat-source water is cooled by the heat source device 10.

[0054] When the temperature TL of the heat source water is maintained at a temperature higher than the low-temperature threshold value Tlow and the temperature TH of the heat source water is maintained at a temperature lower than the high-temperature threshold value Thi, it is assumed that the heat balance is achieved among the plurality of load devices 20 and heating and cooling of the heat source water are not required. Therefore, when the temperature TL of the heat source water is higher than the low-temperature threshold value Tlow (NO in step S30) and the temperature TH of the heat source water is lower than the high-temperature threshold value Thi (NO in step S31), the control device 100 stops the operating state of the heat source machine 10 (step S60). As a result, since the operating state of the heat source machine 10 is maintained in the stopped state, energy efficiency can be improved.

[0055] [Control when the heat source machine 10 is in the cooling operation state] When the heat source machine 10 is in the cooling operation state ("cooling" in step S10), the control device 100 determines whether or not the temperature TL of the heat source water detected by the low-temperature sensor 16 is lower than the low-temperature threshold value Tlow (step S20).

[0056] When the temperature TL of the heat source water is lower than the low-temperature threshold value Tlow, it is assumed that the plurality of load devices 20 are in the full heating state or the heating main body state and the heat balance is not achieved among the plurality of load devices 20 and heating of the heat source water is required. Therefore, when the temperature TL of the heat source water is lower than the low-temperature threshold value Tlow (YES in step S20), the control device 100 changes the operating state of the heat source machine 10 to the heating operation state (step S70). As a result, the operating state of the heat source machine 10 is switched from the cooling operation state to the heating operation state, and the heat source water is heated by the heat source machine 10.

[0057] When the temperature TL of the heat source water is maintained at a temperature equal to or higher than the low-temperature threshold value Tlow (NO in step S20), the control device 100 determines whether or not the temperature TH of the heat source water detected by the high-temperature sensor 17 is lower than the high-temperature threshold value Thi by a reference value ΔH, that is, whether or not TH < Thi - ΔH (step S21).

[0058] When TH < Thi - ΔH (NO in step S21), it is assumed that the heat source water has not been sufficiently cooled and the heat balance cannot be achieved only between the plurality of load devices 20. Therefore, the control device 100 sets the operating state of the heat source machine 10 to the cooling operation state (step S50). As a result, the cooling operation state of the heat source machine 10 is continued, and the cooling of the heat source water by the heat source machine 10 is continued.

[0059] On the other hand, when TH < Thi - ΔH (YES in step S21), it is assumed that the heat source water is sufficiently cooled and the heat balance can be achieved only between the plurality of load devices 20. Therefore, the control device 100 stops the heat source machine 10 (step S60). As a result, energy efficiency can be improved.

[0060] [Control when the heat source machine 10 is in the heating operation state] When the heat source machine 10 is in the heating operation state ("heating" in step S10), the control device 100 determines whether the heat source water temperature TH detected by the high - temperature sensor 17 exceeds the high - temperature threshold value Thi (step S40).

[0061] When the heat source water temperature TH exceeds the high - temperature threshold value Thi, it is assumed that the plurality of load devices 20 are in the full - cooling state or the cooling - dominant state, and the heat balance cannot be achieved between the plurality of load devices 20 and the cooling of the heat source water is required. Therefore, when the heat source water temperature TH exceeds the high - temperature threshold value Thi (YES in step S40), the control device 100 sets the operating state of the heat source machine 10 to the cooling operation state (step S50). As a result, the operating state of the heat source machine 10 is switched from the heating operation state to the cooling operation state, and the heat source water is cooled by the heat source machine 10.

[0062] When the heat source water temperature TH is maintained below the high - temperature threshold value Thi (NO in step S40), the control device 100 determines whether the heat source water temperature TL detected by the low - temperature sensor 16 exceeds a temperature that is ΔL higher than the low - temperature threshold value Tlow, that is, whether TL > Tlow + ΔL (step S41).

[0063] If TL>Thlow+ΔL is not satisfied (NO in step S41), it is assumed that the heat-source water has not yet been heated sufficiently and that the heat balance cannot be achieved among the multiple load devices 20 alone, so the control device 100 sets the operating state of the heat source device 10 to the heating operation state (step S70). As a result, the heating operation state of the heat source device 10 continues, and the heating of the heat-source water by the heat source device 10 continues.

[0064] On the other hand, if TL>Thlow+ΔL (YES in step S41), it is assumed that the heat source water is sufficiently heated and the heat balance is achieved only among the multiple load devices 20, so the control device 100 stops the heat source device 10 (step S60). This can improve energy conservation.

[0065] As described above, the control device 100 according to this embodiment controls the heat source device 10 based on the temperature of the heat source water around the water heat exchanger 15 (the detection results of the low temperature sensor 16 and the high temperature sensor 17) without monitoring the operating states of the multiple load devices 20. Therefore, the heat source device 10 can be controlled autonomously.

[0066] Furthermore, the control device 100 according to this embodiment stops the heat source machine 10 when it is determined that the heat balance is achieved among the plurality of load devices 20 based on the temperature of the heat source water around the water heat exchanger 15. Therefore, the exhaust heat of the plurality of load devices 20 can be recovered more effectively than when the heat source machine 10 is always operated.

[0067] Furthermore, in the air conditioning system 1 according to this embodiment, a water pump for circulating the heat-source water is not provided in the heat source machine 10, and the heat-source water is circulated only by the variable flow pump 23 of the user-side load device 20. Therefore, the heat source machine 10 can have a simpler configuration than when a water pump for circulating the heat-source water is also provided in the heat source machine 10.

[0068] As a result of the above, the air conditioning system 1 according to this embodiment can effectively recover the exhaust heat of the multiple load devices 20, while autonomously controlling the heat source device 10 with a simpler configuration.

[0069] In this embodiment, each of the multiple load devices 20 is provided with a four-way valve 22 (direction switching device) that switches the flow direction of the heat source water, and the four-way valve 22 (direction switching device) is configured not only to switch the flow direction of the heat source water, but also to be able to block the flow of the heat source water.

[0070] 11 is a diagram showing a schematic diagram of the structure of the four-way valve 22. The portion of the four-way valve 22 shown as a circle is cylindrical, rotatable in the circumferential direction, and configured so that the rotational position can be controlled. The portion of the four-way valve 22 shown as two curved lines inside the circle is the flow path of the heat-source water. The portion of the four-way valve 22 shown as a dot is a mark to make it easier to identify the rotational position and has no particular physical meaning.

[0071] 11(A) shows the rotational position state of the four-way valve 22 when the load device 20 is in cooling operation. In this state, the supply side pipe 33 is connected to the low temperature side pipe 31, and the discharge side pipe 34 is connected to the high temperature side pipe 32.

[0072] 11(B) shows the rotational position state of the four-way valve 22 when the load device 20 is in heating operation. In this state, the supply side pipe 33 is connected to the high temperature side pipe 32, and the discharge side pipe 34 is connected to the low temperature side pipe 31.

[0073] 11(C) shows the rotational position state of the four-way valve 22 during the failure mode of the load device 20. In this state, the supply-side pipe 33 and the discharge-side pipe 34 are not connected to either the low-temperature-side pipe 31 or the high-temperature-side pipe 32, and the flow path of the heat-source water is blocked. As a result, the flow rate of the heat-source water becomes zero.

[0074] By configuring the four-way valve 22 as described above, even if the flow-variable pump 23 does not have the function of completely stopping the flow of heat source water, unnecessary flow of heat source water can be reliably stopped by setting the four-way valve 22 to the state shown in Figure 11 (C) during failure mode of the load device 20. [Variation 1] In the above-described first embodiment, an example has been described in which the temperature of the heat source water around the water heat exchanger 15 (heat source water temperatures TL, TH) is used as a parameter for controlling the heat source machine 10.

[0075] However, the parameter for controlling the heat source unit 10 is not necessarily limited to the temperature of the heat source water, and may be the flow direction of the heat source water.

[0076] 12 is a diagram schematically showing an example of the overall configuration of an air conditioning system 2 according to this modified example 1. In the air conditioning system 2, the low temperature sensor 16 and the high temperature sensor 17 of the above-described air conditioning system 1 are replaced with a flow sensor 18. The other hardware configurations of the air conditioning system 2 are the same as those of the above-described air conditioning system 1.

[0077] The flow sensor 18 is disposed in a portion of the high-temperature side pipe 32 near the water heat exchanger 15, and detects the flow direction of the heat source water. The position at which the flow sensor 18 is disposed may be any position inside the water heat exchanger 15 or near the water heat exchanger 15 where the flow direction of the heat source water can be detected, and is not necessarily limited to the high-temperature side pipe 32. For example, the flow sensor 18 may be disposed in a portion of the low-temperature side pipe 31 near the water heat exchanger 15, or may be disposed in the heat source water flow path inside the water heat exchanger 15 (the portion where the low-temperature side pipe 31 and the high-temperature side pipe 32 communicate with each other).

[0078] When the plurality of load devices 20 are in a full cooling state or a cooling-dominated state, as shown in Figures 5 and 7 above, the heat-source water around the water heat exchanger 15 flows in a first direction from the high-temperature side pipe 32 through the water heat exchanger 15 toward the low-temperature side pipe 31. On the other hand, when the plurality of load devices 20 are in a full heating state or a heating-dominated state, the heat-source water around the water heat exchanger 15 flows in a second direction from the low-temperature side pipe 31 through the water heat exchanger 15 toward the high-temperature side pipe 32, as shown in Figures 6 and 8 above. In consideration of this flow of heat-source water, the flow sensor 18 detects the flow direction of the heat-source water as the "cooling direction" when the heat-source water is flowing in the first direction, and detects the flow direction of the heat-source water as the "heating direction" when the heat-source water is flowing in the second direction.

[0079] Furthermore, the flow sensor 18 has the function of detecting the flow direction of the heat-source water, and also has the function of linearly detecting the flow rate of the heat-source water.

[0080] 13 is a flowchart showing an example of a processing procedure executed by the control device 100 according to Modification 1 when controlling the heat source device 10. This flowchart is repeatedly executed every time a predetermined condition is met (for example, every predetermined period).

[0081] First, the control device 100 determines whether the flow rate of the heat source water around the water heat exchanger 15 detected by the flow sensor 18 exceeds a threshold value (step S80).

[0082] If the flow rate of the heat source water around the water heat exchanger 15 is less than the threshold value (NO in step S80), it is assumed that the flow rate balance of the heat source water is balanced among the multiple load devices 20 and that operating the heat source machine 10 will not have much effect on the temperature of the heat source water circulating among the multiple load devices 20, so the control device 100 stops the heat source machine 10 (step S60). This prevents the heat source machine 10 from operating unnecessarily, thereby improving energy conservation.

[0083] On the other hand, if the flow rate of the heat source water around the water heat exchanger 15 exceeds the threshold value (YES in step S80), the control device 100 determines whether the flow direction of the heat source water detected by the flow sensor 18 is the cooling direction (step S82).

[0084] If the flow direction of the heat source water is the cooling direction (YES in step S82), it is assumed that multiple load devices 20 are in a full cooling state or a cooling-dominant state and that cooling of the heat source water is required, so the control device 100 changes the operating state of the heat source unit 10 to a cooling operation state (step S50).

[0085] On the other hand, if the flow direction of the heat source water is the heating direction (NO in step S82), it is assumed that the multiple load devices 20 are in a full heating state or a heating-dominant state and that heating of the heat source water is required, so the control device 100 sets the operating state of the heat source unit 10 to a heating operation state (step S70).

[0086] When the heat source unit 10 is operated in step S50 or step S70, the control device 100 adjusts the capacity of the heat source unit 10 according to the flow rate of the heat source water around the water heat exchanger 15 detected by the flow sensor 18 (step S84). It is assumed that the greater the flow rate of the heat source water around the water heat exchanger 15, the greater the imbalance in the flow rate of the heat source water among the multiple load devices 20, and the greater the heat exchange amount required in the water heat exchanger 15. Therefore, for example, the greater the flow rate of the heat source water detected by the flow sensor 18, the higher the rotation speed of the compressor 11 of the heat source unit 10 (increasing the refrigerant flow rate in the primary refrigerant circuit), thereby increasing the heat exchange amount in the water heat exchanger 15. This allows the temperature of the heat source water to be appropriately adjusted to the temperature required by the multiple load devices 20.

[0087] As described above, the heat source unit 10 may be controlled based on the flow direction and flow rate of the heat source water inside or around the water heat exchanger 15 .

[0088] The flow rate detection function of the flow sensor 18 is not necessarily limited to a function that linearly detects the flow rate of the heat-source water, as long as it can at least detect that the flow rate of the heat-source water is below a threshold. For example, the flow sensor 18 may be configured to not output a signal indicating the detection result when the flow rate of the heat-source water is below the threshold, as it is unable to detect the flow direction of the heat-source water. In this case, the process of step S84 in FIG. 13 (the process of adjusting the capacity of the heat source unit 10 according to the flow rate of the heat-source water) can be omitted, and the process of step S80 (the process of determining whether the flow rate of the heat-source water is below the threshold) can be performed depending on whether the flow sensor 18 outputs a detection result.

[0089] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0090] 1,2 Air conditioning system, 10 Heat source machine, 11 Compressor, 12,22 Four-way valve, 13 Air heat exchanger, 14 Pressure reducing device, 15 Water heat exchanger, 16 Low temperature sensor, 17 High temperature sensor, 18 Flow sensor, 20 Load device, 21 Water-cooled heat pump, 23 Variable flow pump, 24 Opening and closing valve, 31 Low temperature side piping, 31a,32a Connection part, 31b,32b End, 32 High temperature side piping, 33 Supply side piping, 34 Discharge side piping, 100 Control device.

Claims

1. An air conditioning system for heating and cooling multiple spaces, a first pipe through which heat source water flows; a second pipe that is connected to the first pipe and through which heat source water having a temperature higher than that of the heat source water of the first pipe flows; a plurality of load devices each connected to the first pipe and the second pipe and configured to individually heat and cool the plurality of spaces; a heat source machine having a refrigerant circuit including a water heat exchanger that exchanges heat between heat-source water flowing through a communication portion between the first pipe and the second pipe and a primary refrigerant; Each of the plurality of load devices When heating the space, heat source water is taken in from the second pipe, the heat source water taken in from the second pipe is used to heat the space, and the heat source water after being used to heat the space is discharged to the first pipe, When cooling the space, heat source water is taken in from the first pipe, the space is cooled using the heat source water taken in from the first pipe, and the heat source water after being used for cooling the space is discharged to the second pipe, The heat source machine is configured to be able to switch its operating state between a heating operation state in which the primary refrigerant is circulated so as to heat the heat source water in the water heat exchanger, a cooling operation state in which the primary refrigerant is circulated so as to cool the heat source water in the water heat exchanger, and a stop state in which the circulation of the primary refrigerant is stopped, The air conditioning system further comprises: a detection device for detecting the state of the heat source water in the water heat exchanger or around the water heat exchanger; an air conditioning system comprising: a control device that controls the heat source machine to one of the heating operation state, the cooling operation state, and the stopped state based on the detection result of the detection device.

2. the detection device includes a first temperature sensor and a second temperature sensor each detecting a temperature of the heat source water as a state of the heat source water around the water heat exchanger, the first temperature sensor detects the temperature of the heat source water in the first pipe around the water heat exchanger; the second temperature sensor detects the temperature of the heat source water in the second pipe around the water heat exchanger; When the heat source machine is in the stopped state, the control device maintaining the heat source machine in the stopped state when the temperature detected by the first temperature sensor is higher than a first threshold value and the temperature detected by the second temperature sensor is lower than a second threshold value; when the temperature detected by the first temperature sensor falls below the first threshold value, the operation state of the heat source machine is switched to the heating operation state; The air conditioning system according to claim 1 , wherein the heat source unit is switched to the cooling operation state when the temperature detected by the second temperature sensor exceeds the second threshold value.

3. When the heat source unit is in the heating operation state, the control device when the temperature detected by the second temperature sensor exceeds the second threshold value, the heat source machine is switched to the cooling operation state; If the temperature detected by the second temperature sensor does not exceed the second threshold value and the temperature detected by the first temperature sensor does not exceed a value higher than the first threshold value by a first reference value, the heat source machine is maintained in the heating operation state; The air conditioning system of claim 2, wherein the heat source unit is switched to the stopped state when the temperature detected by the second temperature sensor does not exceed the second threshold value and the temperature detected by the first temperature sensor exceeds a value higher than the first threshold value by the first reference value.

4. When the heat source unit is in the cooling operation state, the control device When the temperature detected by the first temperature sensor falls below the first threshold value, the heat source machine is switched to the heating operation state; maintain the heat source machine in the cooling operation state when the temperature detected by the first temperature sensor is not below the first threshold value and the temperature detected by the second temperature sensor is not below a value lower than the second threshold value by a second reference value; The air conditioning system of claim 2 or 3, wherein the heat source unit is switched to the stopped state when the temperature detected by the first temperature sensor is not below the first threshold value and the temperature detected by the second temperature sensor is below a value that is lower than the second threshold value by the second reference value.

5. the detection device includes a flow sensor that detects the flow direction of the heat source water as a state of the heat source water in or around the water heat exchanger, The control device When the direction detected by the flow sensor is a first direction from the second pipe through the water heat exchanger toward the first pipe, the heat source unit is put into the cooling operation state; The air conditioning system according to claim 1, wherein the heat source unit is put into the heating operation state when the direction detected by the flow sensor is a second direction from the first pipe through the water heat exchanger toward the second pipe.

6. the flow sensor is configured to detect a flow rate of the heat source water in addition to a flow direction of the heat source water; The air conditioning system according to claim 5 , wherein the control device brings the heat source unit into the stopped state when the flow rate detected by the flow sensor is less than a threshold value, regardless of the direction detected by the flow sensor.

7. The refrigerant circuit of the heat source machine includes, in addition to the water heat exchanger, a compressor, a four-way valve, an air heat exchanger, and a pressure reduction device, and is configured such that by setting the four-way valve to a first state and operating the compressor, the primary refrigerant circulates through the compressor, the air heat exchanger, the pressure reduction device, and the water heat exchanger in that order, and by setting the four-way valve to a second state and operating the compressor, the primary refrigerant circulates through the compressor, the water heat exchanger, the pressure reduction device, and the air heat exchanger in that order, The control device When the heat source unit is put into the cooling operation state, the four-way valve is put into the first state to operate the compressor; The air conditioning system according to claim 1 , wherein when the heat source unit is in the heating operation state, the four-way valve is set to the second state to operate the compressor.

8. Each of the plurality of load devices has a direction switching device that switches the flow direction of the heat source water, The air conditioning system described in claim 7, wherein the direction switching device is configured to be switchable between a first state in which the flow direction of the heat source water is from the second pipe to the first pipe, a second state in which the flow direction of the heat source water is from the first pipe to the second pipe, and a third state in which the flow of the heat source water is blocked and the flow rate of the heat source water is set to zero.

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