Air conditioning system

Abstract

To provide an air conditioning system capable of achieving energy saving.SOLUTION: An air conditioning system for conditioning a target space (S) includes a heat source unit (20) and a utilization unit (30) provided with a predetermined heat medium circuit (C). The heat source unit (20) exchanges heat with a heat medium in the heat medium circuit (C). The utilization unit (30) comprises: a heat exchanger (33) that is connected to the heat medium circuit (C), and exchanges heat with air in the target space (S); and a flow rate control valve (34) that adjusts a flow rate of the heat medium flowing through the heat exchanger (33). The utilization unit has a first conveying unit (51) that conveys the heat medium, and a control unit (100) that controls the upper limit of an opening degree of the flow rate control valve (34).SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an air conditioning system.

Background Art

[0002] The air conditioning system disclosed in Patent Document 1 performs air conditioning such as cooling, heating, ventilation, dehumidification, and / or humidification in a target space by taking in and conditioning outside air and supplying it to the target space.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the operating capacity of the heat source equipment is larger than the load capacity of the air conditioner, a predetermined air state is maintained. However, when the load capacity of the air conditioner becomes larger than the operating capacity of the heat source equipment due to a change in the air conditioning load, the room temperature cannot be maintained at the preset target temperature, and the opening degree of the flow rate adjustment valve of the air conditioner may be increased to increase the flow rate of the fluid, which is the heat medium.

[0005] However, since the capacity of the air conditioner is limited, even if the opening degree of the flow rate adjustment valve of the air conditioner is excessively increased, the room temperature cannot reach the target temperature. Thus, even though the room temperature cannot reach the target temperature, if fluid continues to flow through the flow rate adjustment valve at an excessive opening degree, the load on the pump that conveys the fluid increases, and the COP of the heat source equipment deteriorates.

[0006] An object of the present disclosure is to provide an air conditioning system that achieves energy conservation.

Means for Solving the Problems

[0007] The first aspect of this disclosure is, An air conditioning system for air conditioning a target space (S), comprising a heat source unit (20) and a utilization unit (30) provided with a predetermined heat transfer medium circuit (C), The heat source unit (20) exchanges heat with the heat transfer medium of the heat transfer medium circuit (C), The utilization unit (30) includes a heat exchanger (33) connected to the heat transfer circuit (C) that exchanges heat with the air in the target space (S), and a flow control valve (34) that adjusts the flow rate of the heat transfer medium flowing through the heat exchanger (33). A first transport unit (51) for transporting the heat transfer medium, The system includes a control unit (100) that controls the upper limit of the opening degree of the flow control valve (34). It is an air conditioning system.

[0008] By limiting the upper limit of the opening degree of the flow control valve (34), the opening degree of the flow control valve (34) is prevented from reaching its maximum opening degree. As a result, for example, when the air conditioning load exceeds the design capacity of the heat exchanger (33), even if the flow control valve (34) is opened beyond a predetermined value, the measured temperature of the target space (S) will not easily reach the set temperature. In such a situation, even if the opening degree of the flow control valve (34) is increased further, the heat exchange efficiency of the heat exchanger (33) will only slightly improve, and the measured temperature will not reach the set temperature. On the contrary, the load on the first transport unit (51) will increase due to the increased flow rate of the heat transfer medium. Thus, by setting an upper limit on the opening degree of the flow control valve (34), even in the above situation, the flow control valve (34) will not open too much, the increase in load on the first transport unit (51) will be suppressed, and the deterioration of the COP of the heat source unit (20) can be suppressed. In other words, energy saving can be achieved.

[0009] A second aspect is, in the first aspect, The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) based on ΔMV, which is the amount of change in the opening degree of the flow control valve (34), and Δ(PV-SV), which is the difference in the amount of change in the difference between the temperature of the target space (S) after the change in the opening degree of the flow control valve (34) and the set temperature.

[0010] In the second embodiment, the upper limit of the opening degree of the flow control valve (34) can be easily limited based on the amount of change in the opening degree of the flow control valve (34) and the amount of change in the difference between the measured temperature and the set temperature.

[0011] A third aspect is, in the second aspect, The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) based on the value of the ratio of Δ(PV-SV) to ΔMV.

[0012] In the third embodiment, it is possible to determine whether the flow control valve (34) should be restricted from opening any further based on the ratio of Δ(PV-SV) to ΔMV.

[0013] The fourth aspect is one of the first to third aspects, The heat transfer medium circuit (C) is configured such that a plurality of the utilization units (30) are connected in parallel to the heat source unit (20). The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) for each of the utilization units (30).

[0014] In the fourth embodiment, the upper limit of the opening degree of the flow control valve (34) can be limited for each user unit (30).

[0015] The fifth aspect is as described in the first to fourth aspects. The heat transfer medium circuit (C) has a bypass channel (BP) through which the heat transfer medium flowing out from the heat source unit (20) bypasses the utilization unit (30). A second transport unit (52) for transporting the heat transfer medium is connected to the heat transfer medium circuit (C). Of the heat transfer medium circuit (C), the first transport unit (51) is connected to the heat source unit (20) side via a bypass flow path (BP), and the second transport unit (52) is connected to the utilization unit (30) side.

[0016] In the fifth embodiment, the increase in load on the first conveying unit (51) and the second conveying unit (52) can be suppressed, thereby achieving energy savings.

Brief Description of the Drawings

[0017] [Figure 1] FIG. 1 is a schematic piping system diagram of an air conditioning system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the relationship between the control unit and various devices of the air conditioning system. [Figure 3] FIG. 3 is a flowchart showing the control flow of the upper limit opening degree of the flow rate adjustment valve in the cooling operation. [Figure 4] FIG. 4 is a flowchart showing the control flow of the upper limit opening degree of the flow rate adjustment valve in the heating operation. [Figure 5] FIG. 5 is a schematic piping system diagram corresponding to FIG. 1 of the air conditioning system in Modification 1. [Figure 6] FIG. 6 is a schematic piping system diagram corresponding to FIG. 1 of the air conditioning system in Modification 2.

Modes for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses. In addition, the respective configurations of the following embodiments, modifications, and other examples can be combined or partially replaced within the scope where the present invention can be implemented.

[0019] (1) Overall Configuration of the Air Conditioning System The air conditioning system (10) of the present disclosure is a so-called central air conditioning system. The air conditioning system (10) air - conditions a target space (S) within a building such as a building, factory, warehouse, public facility, etc. The air conditioning system (10) takes in outside air, processes it, and then supplies the processed air to the target space (S).

[0020] The air conditioning system (10) mainly comprises a chiller unit (20), an air conditioning device (30), and a control unit (100). The chiller unit (20) has a refrigerant circuit (R). The air conditioning device (30) has a water circuit (C). The chiller unit (20) exchanges heat with the water, which is the heat transfer medium in the water circuit (C). The water in the water circuit (C) is cooled or heated by the heat exchange between the refrigerant in the refrigerant circuit (R) and the water in the water circuit (C).

[0021] (1-1) Chiller Unit The chiller unit (20) is an example of a heat source unit (20). The chiller unit (20) includes a compressor (21), a water heat exchanger (22), an expansion valve (23), a heat source heat exchanger (24), a four-way switching valve (25), a heat source fan (26), and a first water pump (51). The compressor (21), water heat exchanger (22), expansion valve (23), heat source heat exchanger (24), and four-way switching valve (25) are connected to a refrigerant circuit (R).

[0022] The chiller unit (20) performs a first refrigeration cycle operation and a second refrigeration cycle operation. In the first refrigeration cycle operation, the heat source heat exchanger (24) functions as an evaporator, and in the second refrigeration cycle operation, the heat source heat exchanger (24) functions as a heat radiator.

[0023] The compressor (21) compresses the inhaled refrigerant to a high pressure and discharges it. The compressor (21) is of variable capacity. The compressor (21) has a positive displacement compression element, such as a scroll type, and the compression element is rotationally driven by a motor. The motor frequency is controlled by an inverter, which controls the capacity of the compressor (21).

[0024] The expansion valve (23) reduces the pressure of the refrigerant or adjusts the flow rate of the refrigerant. The expansion valve (23) is an electrically operated valve with an open-degree controllable function.

[0025] The heat source heat exchanger (24) is a fin-and-tube type air heat exchanger. The heat source heat exchanger (24) exchanges heat between the refrigerant flowing inside it and the outdoor air.

[0026] The heat source fan (26) transports outside air to the heat source heat exchanger (24). The heat source fan (26) is controlled to have a variable airflow.

[0027] The four-way directional control valve (25) switches the flow of the refrigerant circuit (R). The four-way directional control valve (25) has four connection ports, which are connected to the suction piping and discharge piping of the compressor (21), the gas side of the refrigerant flow path of the water heat exchanger (22), and the gas side of the outdoor heat exchanger (33), respectively. Specifically, the four-way directional control valve (25) can be switched between a first state and a second state. The first state is a state in which the gas side of the refrigerant flow path of the water heat exchanger (22) is connected to the suction piping of the compressor (21), and the discharge piping of the compressor (21) is connected to the gas side of the outdoor heat exchanger (33) (solid line of the four-way directional control valve (25) in Figure 1). The second state is one in which the discharge piping of the compressor (21) is connected to the gas side of the refrigerant flow path of the water heat exchanger (22), and the gas side of the outdoor heat exchanger (33) is connected to the suction piping of the compressor (21) (dashed line of the four-way switching valve (25) in Figure 1). The four-way switching valve (25) is controlled to the first state during the first refrigeration cycle operation and to the second state during the second refrigeration cycle operation.

[0028] The water heat exchanger (22) exchanges heat between the water in the water circuit (C) and the refrigerant in the refrigerant circuit (R). The water heat exchanger (22) has a water channel (22a) that communicates with the water circuit (C) and a refrigerant channel (22b) that communicates with the refrigerant circuit (R). The water in the water channel (22a) is heated or cooled by exchanging heat with the refrigerant passing through the refrigerant channel (22b).

[0029] The first water pump (51) is an example of the first conveying unit (51). The first water pump (51) is connected to the water circuit (C). The first water pump (51) conveys water from the water circuit (C). The first water pump (51) is driven by a motor, and the rotational speed of the first water pump (51) is adjusted by inverter control of the motor.

[0030] (1-2) Air conditioning system The air conditioning unit (30) includes an indoor heat exchanger (33), a flow control valve (34), and an air supply fan (35). The indoor heat exchanger (33), air supply fan (35), and flow control valve (34) are connected to a water circuit (C). The water circuit (C) is an example of a predetermined heat transfer medium circuit (C) of the present disclosure. The water flowing through the water circuit (C) is the heat transfer medium of the present disclosure.

[0031] The indoor heat exchanger (33) cools or heats outside air taken in from outside. The indoor heat exchanger (33) has heat transfer tubes and heat transfer fins that communicate with a water circuit (C). Heat exchange takes place between the outside air passing around the heat transfer tubes and heat transfer fins and the water passing through the heat transfer tubes. The indoor heat exchanger (33) is an example of the heat exchanger (33) of this disclosure.

[0032] The supply fan (35) transports the incoming outside air to the target space (S). For example, the air conditioning unit (30) is connected to a duct (not shown) that communicates with the target space (S), and the outside air taken in by the supply fan (35) is processed in the air conditioning unit (30) and then blown out to the target space (S) via the duct. The supply fan (35) is configured to have a variable airflow.

[0033] The flow control valve (34) controls the flow rate of water flowing into the indoor heat exchanger (33). The flow control valve (34) is an electrically operated valve with adjustable opening. The flow control valve (34) adjusts the opening of the water pipes that make up the water circuit (C).

[0034] (2) Temperature sensor The air conditioning unit (30) includes a first temperature sensor (41), a second temperature sensor (42), a third temperature sensor (43), and a water temperature sensor (44). The first temperature sensor (41) detects the air temperature of the target space (S). The second temperature sensor (42) detects the discharge temperature of the air conditioning unit (30) to the target space (S). The third temperature sensor (43) detects the intake temperature of the outside air drawn into the air conditioning unit (30). The water temperature sensor (44) detects the water temperature of the water circuit (C) flowing out from the water heat exchanger (22).

[0035] (3) Control Unit As shown in Figure 2, the control unit (100) is composed of memory, a CPU, and the like. In this embodiment, the control unit (100) has a first control unit (101) and a second control unit (102). The first control unit (101) is provided in the chiller unit (20). The second control unit (102) is provided in the air conditioning system (30). The first control unit (101) and the second control unit (102) may be connected to each other so as to be able to communicate with each other.

[0036] The first control unit (101) is connected to various components of the chiller unit (20). The first control unit (101) controls various components such as the compressor (21), the first water pump (51), the expansion valve (23), and the heat source fan (26).

[0037] The second control unit (102) is connected to various components of the air conditioning system (30). The second control unit (102) controls the operation of components such as the flow control valve (34) and the air supply fan (35).

[0038] (4) Operation of the air conditioning system When the air conditioning system (10) is in operation, the first water pump (51) is driven and water circulates in the water circuit (C). Also, the compressor (21) is driven and refrigerant circulates in the refrigerant circuit (R). The air conditioning system (10) performs cooling operation and heating operation. Cooling operation is the first refrigeration cycle operation. Heating operation is the second refrigeration cycle operation.

[0039] During operation of the air conditioning system (10), the water in the water circuit (C) is cooled or heated to a target water temperature by exchanging heat with the refrigerant flowing through the refrigerant passage (22b) in the water heat exchanger (22). The water cooled or heated in the water heat exchanger (22) flows into the air conditioning unit (30) and is heated or cooled by exchanging heat with the outside air in the indoor heat exchanger (33). The water that has passed through the air heat exchanger (33) flows back into the water heat exchanger (22).

[0040] (4-1) Cooling operation The cooling operation is a cooling operation that cools the air in the target space (S). In the refrigerant circuit (R), the refrigerant is compressed in the compressor (21) and discharged as high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor (21) condenses or releases heat by exchanging heat with the air transported by the heat source fan (26) in the heat source heat exchanger (24). After passing through the heat source heat exchanger (24), the refrigerant is depressurized in the expansion valve (23) to become low-pressure refrigerant and then flows into the water heat exchanger (22). The low-pressure refrigerant that flows into the water heat exchanger (22) evaporates by exchanging heat with the water flowing in the water circuit (C). The low-pressure refrigerant that has passed through the water heat exchanger (22) is drawn back into the compressor (21).

[0041] In the water heat exchanger (22), the water in the water circuit (C) is cooled to the target water temperature. The water in the water circuit (C), which has exchanged heat with the refrigerant in the water heat exchanger (22), is heated in the indoor heat exchanger (33) by exchanging heat with outside air taken in from the intake by the supply air fan (35). The outside air that has exchanged heat in the indoor heat exchanger (33) is cooled and blown out into the target space (S) from the outlet of the air conditioner (30). As a result, the indoor air temperature in the target space (S) is lowered to the target temperature.

[0042] (4-2) Heating operation The heating operation is a heating operation that heats the air in the target space (S). During the heating operation, the refrigerant is compressed in the compressor (21) and discharged as high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor (21) condenses or releases heat by exchanging heat with water flowing through the water circuit (C) in the water heat exchanger (22). After passing through the water heat exchanger (22), the refrigerant is depressurized in the expansion valve (23) to become low-pressure refrigerant and then flows into the outdoor heat exchanger (33). The low-pressure refrigerant that flows into the outdoor heat exchanger (33) evaporates by exchanging heat with the air transported by the heat source fan (26). The low-pressure refrigerant that has passed through the outdoor heat exchanger (33) is drawn back into the compressor (21).

[0043] In the water heat exchanger (22), the water in the water circuit (C) is heated to the target water temperature. The water in the water circuit (C), which has exchanged heat with the refrigerant in the water heat exchanger (22), is cooled in the indoor heat exchanger (33) by exchanging heat with outside air taken in from the intake by the supply air fan (35). The outside air that has exchanged heat in the indoor heat exchanger (33) is heated and blown out from the outlet of the air conditioner (30) into the target space (S). As a result, the indoor air temperature in the target space (S) rises to the target temperature.

[0044] (5) Challenges when the air conditioning load becomes excessive The air conditioning system for the target space controls the flow control valve by adjusting the opening degree based on the difference between the current air quality (dry-bulb temperature, relative humidity, etc.) of the target space (S) and the preset air quality (target value), thereby maintaining the air quality at the preset value.

[0045] In a central air conditioning system, if the operating capacity of the chiller unit is greater than the load capacity of the air conditioning system, a predetermined air condition is maintained. However, if the load capacity of the air conditioning system becomes greater than the operating capacity of the chiller unit due to a change in the air conditioning load of the target space, the flow control valve of the air conditioning system can no longer maintain the preset air condition (target value). As a result, the opening of the flow control valve becomes excessively large, and under certain conditions, it may open to its maximum opening. In recent years, with the increase in air conditioning load due to global warming and the increase in the load of production facilities, the air conditioning system's capacity is naturally limited, and even if the opening of the flow control valve becomes excessively large, it cannot maintain the predetermined air condition. In other words, even if the opening of the flow control valve becomes excessively large, it is being controlled toward a target value that cannot be reached.

[0046] In conventional control systems, flow control valves are controlled based on the difference between the current value and the target value of the target air. This can lead to a deterioration of the COP due to partial load operation of the heat source, and unnecessary power consumption in the conveying system, such as pumps.

[0047] To address these challenges, the air conditioning system (10) of this disclosure includes a control unit (100) that controls the upper limit of the opening degree of the flow control valve (34). The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) when predetermined conditions are met. The predetermined conditions are met, for example, when the air conditioning load of the target space (S) exceeds the cooling capacity of the air conditioning unit (30). The predetermined conditions are also met, for example, when the load capacity of the air conditioning unit (30) exceeds the operating capacity of the chiller unit (20). In the air conditioning system (10) of this disclosure, when such conditions are met, excessive opening of the flow control valve (34) is suppressed, and excessive operation of the water pump is suppressed. As a result, an increase in power consumption and deterioration of COP are suppressed. The operation of the control unit will now be described.

[0048] (6) Operation of the control unit The control unit (100) of this embodiment limits the upper limit of the opening degree of the flow control valve (34) based on ΔMV, which is the amount of change in the opening degree of the flow control valve (34), and Δ(PV-SV), which is the difference in the amount of change in the difference between the temperature of the target space (S) after the opening degree of the flow control valve (34) and the set temperature. PV indicates the current air temperature of the target space (S). The air temperature of the target space (S) is based on a measurement value by the second temperature sensor (42). The air temperature of the target space (S) may also be based on a measurement value by the first temperature sensor (41). SV indicates the target air temperature of the target space. SV is the set temperature of the target space (S). MV indicates the control output value (%) output to the flow control valve (34), where the flow control valve (34) is fully open when MV is 100%, and fully closed when MV is 0%. The control unit (100) below may be the first control unit (101) or the second control unit (102).

[0049] Using Figures 3 and 4, the upper limit control of the opening degree of the flow control valve (34) will be explained for both cooling operation and heating operation. The values ​​A1, A2, B1, B2, C1, C2, D1, D2, E1, E2, OH1, and OH2 shown below are arbitrary values, and are set by the user, for example.

[0050] (6-1) Cooling operation In step S11, the control unit (100) determines whether the flow control valve (34) is open to a predetermined degree or greater. Specifically, the control unit (100) determines whether the MV is greater than or equal to a predetermined value (A1%). If the MV is determined to be greater than or equal to A1% (YES in step S11), step S12 is executed. If the MV is less than A1% (NO in step S11), step S11 is executed again.

[0051] In step S12, the control unit (100) determines whether Δ(PV-SV), which is the difference between PV and SV, is greater than or equal to a predetermined value (B1). If it is determined that Δ(PV-SV) is greater than or equal to B1 (YES in step S12), step S13 is executed. If it is determined that Δ(PV-SV) is less than B1 (NO in step S12), step S11 is executed again.

[0052] In step S13, the control unit (100) determines whether the value of Δ(PV-SV) with respect to ΔMV (Δ(PV-SV) / ΔMV) is greater than or equal to a predetermined value (C1). If it is determined that Δ(PV-SV) / ΔMV is greater than or equal to C1 (YES in step S13), step S14 is executed. If it is determined that Δ(PV-SV) / ΔMV is less than C1 (NO in step S13), step S11 is executed again. Note that ΔMV is, for example, a constant change in opening (e.g., +5%).

[0053] In step S14, the control unit (100) limits the opening degree of the flow control valve (34). In this embodiment, the upper limit output value (OH1) is limited within the control unit (100) with the opening degree MV+D1 (a predetermined value) at the time of determination in step S13 as the upper limit. As a result, the opening degree of the flow control valve (34) does not become greater than the opening degree corresponding to the upper limit output value OH1. OH1 is an output value less than 100%. OH1 may be a preset value.

[0054] In step S15, the control unit (100) determines whether the difference between OH1 and MV is greater than a predetermined value (E1). If it is determined that the difference between OH1 and MV is greater than or equal to E1 (YES in step S15), step S16 is executed. If it is determined that the difference between OH1 and MV is less than E1 (NO in step S15), step S15 is executed again.

[0055] In step S16, the control unit (100) releases the restriction on the opening degree of the flow control valve (34) in step S14.

[0056] In step S17, the control unit (100) determines whether it has received a signal instructing the air conditioning system (30) to stop operation. If it is determined that a signal to stop operation has been received (YES in step S17), this control flow ends. If it is determined that a signal to stop operation has not been received (NO in step S17), step S11 is executed again.

[0057] (6-2) Heating operation In step S21, the control unit (100) determines whether the flow control valve (34) is open to a predetermined degree or greater. Specifically, the control unit (100) determines whether MV is greater than or equal to a predetermined value (A2%). If MV is determined to be greater than or equal to A2% (YES in step S21), step S22 is executed. If MV is less than A2% (NO in step S21), step S21 is executed again.

[0058] In step S22, the control unit (100) determines whether Δ(SV-PV), which is the difference between SV and PV, is greater than or equal to a predetermined value (B2). If it is determined that Δ(SV-PV) is greater than or equal to B2 (YES in step S22), step S23 is executed. If it is determined that Δ(SV-PV) is less than B2 (NO in step S22), step S21 is executed again.

[0059] In step S23, the control unit (100) determines whether the value of Δ(SV-PV) with respect to ΔMV (Δ(SV-PV) / ΔMV) is greater than or equal to a predetermined value (C2). If it is determined that Δ(SV-PV) / ΔMV is greater than or equal to C2 (YES in step S23), step S24 is executed. If it is determined that Δ(SV-PV) / ΔMV is less than C2 (NO in step S23), step S21 is executed again. Note that ΔMV is, for example, a constant change in opening (e.g., +5%).

[0060] In step S24, the control unit (100) limits the opening degree of the flow control valve (34). In this embodiment, the upper limit output value (OH2) is output to the flow control valve (34), with the opening degree MV+D2 (a predetermined value) at the time of determination in step S23 being the upper limit. As a result, the opening degree of the flow control valve (34) does not become greater than the opening degree corresponding to the upper limit output value OH2. OH2 is an output value less than 100%. OH2 may be a preset value.

[0061] In step S25, the control unit (100) determines whether the difference between OH2 and MV is greater than a predetermined value (E2). If it is determined that the difference between OH2 and MV is greater than or equal to E2 (YES in step S25), step S26 is executed. If it is determined that the difference between OH2 and MV is less than E2 (NO in step S25), step S25 is executed again.

[0062] In step S26, the control unit (100) releases the restriction on the opening degree of the flow control valve (34) in step S24.

[0063] In step S27, the control unit (100) determines whether it has received a signal instructing the air conditioning system (30) to stop operation. If it is determined that a signal to stop operation has been received (YES in step S27), this control flow ends. If it is determined that a signal to stop operation has not been received (NO in step S27), step S21 is executed again.

[0064] (7) Characteristics (7-1) Feature 1 The air conditioning system (10) of this embodiment includes a control unit (100) that controls the upper limit of the opening degree of the flow control valve (34) of the water circuit (C). This prevents the flow control valve (34) from opening to its maximum degree. By setting an upper limit on the opening degree of the flow control valve (34) in this way, it is possible to prevent the flow control valve (34) from opening too much, for example, even when the air conditioning load exceeds the design capacity of the heat exchanger (33). As a result, the increase in load on the first water pump (51) is suppressed, and the deterioration of the COP of the heat source unit (20) is suppressed. In other words, energy saving can be achieved.

[0065] (7-2) Feature 2 The air conditioning system (10) of this embodiment limits the upper limit of the opening degree of the flow control valve (34) based on ΔMV, which is the change in the opening degree of the flow control valve (34), and Δ(PV-SV), which is the difference between the change in the difference between the temperature of the target space (S) after the change in the opening degree of the flow control valve (34) and the set temperature. This makes it possible to easily limit the upper limit of the opening degree of the flow control valve (34) based on the change in the opening degree of the flow control valve (34) and the change in the difference between the measured temperature and the set temperature.

[0066] (7-3) Feature 3 The air conditioning system (10) of this embodiment limits the upper limit of the opening degree of the flow control valve (34) based on the value of the ratio of Δ(PV-SV) to ΔMV. In this way, it is possible to determine whether the flow control valve (34) should be restricted from opening any further based on the value of the ratio of Δ(PV-SV) to ΔMV.

[0067] (8) Variation 1 As shown in Figure 5, the air conditioning system (10) may comprise multiple air conditioning units (30). Each air conditioning unit (30) is provided in a plurality of target spaces (S). The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) for each air conditioning unit (30). The control unit (100) executes the control flow of the above embodiment for each air conditioning unit (30).

[0068] (9) Modification 2 As shown in Figure 6, the air conditioning system (10) of Modified Example 2 has a bypass channel (BP) provided in the water circuit (C). In the bypass channel (BP), the water whose heat has been exchanged in the water heat exchanger (22) bypasses the air conditioning unit (30). The water circuit (C) of Modified Example 2 has a primary water circuit (C1) connected to the chiller unit (20) and a secondary water circuit (C2) connected to the air conditioning unit (30), with the bypass channel (BP) in between.

[0069] The air conditioning system (10) has a second water pump (52) that transports water from the water circuit (C). The second water pump (52) is an example of a second transport unit (52). The operation of the second water pump (52) is controlled by a control unit (100). Of the water circuit (C), the first water pump (51) is connected to the chiller unit (20) side via a bypass flow path (BP), and the second water pump (52) is connected to the air conditioning device (30) side. That is, the first water pump (51) is connected to the primary water circuit (C1), and the second water pump (52) is connected to the secondary water circuit (C2). The first water pump (51) transports water from the primary water circuit (C1), and the second water pump (52) transports water from the secondary water circuit (C2).

[0070] In an air conditioning system (10) having such a water circuit (C), when the air condition in the target space (S) reaches the set state, the opening of the flow control valve (34) is controlled normally. At this time, the water flowing through the water circuit (C) circulates at an appropriate flow rate, and a portion of the water cooled by the water heat exchanger (22) flows into the bypass channel (BP) and circulates in the primary water circuit (C1).

[0071] However, if the air conditioning load of the target space (S) exceeds the cooling capacity of the indoor unit and the capacity of the chiller unit (20), the flow control valve (34) of the air conditioning device (30) will open excessively, resulting in the problems described in the above embodiment. Specifically, the flow rate of water flowing through the secondary water circuit (C2) to which the air conditioning device (30) is connected will increase excessively, and the flow rate of water flowing through the primary water circuit (C1) to which the chiller unit (20) is installed will become insufficient.

[0072] In other words, the chilled water heat-exchanged in the chiller unit (20) and some of the excess water heated in the secondary water circuit (C2) merge in the bypass channel (BP). As a result, the temperature of the water transported to the secondary water circuit (C2) rises, making it difficult for the air conditioner (30) to cool the air in the target space (S), and causing the opening of the flow control valve (34) to increase further. This results in excessive operating load on the first water pump (51) and the second water pump (52), making it impossible to suppress the increase in power consumption and deterioration of the COP.

[0073] Even for an air conditioning system (10) having such a water circuit (C) (primary water circuit (C1) and secondary water circuit (C2)), the control unit (100) executes the control flow of the above embodiment, so that the opening of the flow control valve (34) does not become fully open, and the water flowing to the air conditioner (30) becomes a flow rate equivalent to the load. Since the air condition in the target space (S) has not reached the set state, the air conditioner (30) outputs a flow rate request equivalent to the load, and the chiller unit (20) is temporarily unable to follow the load condition, but as a result of suppressing an excess of water in the secondary water circuit (C2), the water heated in the air conditioner (30) does not flow into the bypass channel (BP) and merge with the water cooled in the primary water circuit (C1). This results in only a time delay in the load-up of the chiller unit (20) and suppresses the temperature rise of the water transported from the primary water circuit (C1) to the secondary water circuit (C2).

[0074] (10) Other embodiments In the above embodiments and their respective modifications, the upper limit control of the opening degree of the flow control valve (34) may be performed by omitting steps S11 and S21. That is, the control unit (100) may perform the upper limit control of the opening degree of the flow control valve (34) only based on the value of Δ(PV-SV), which is the difference in the amount of change between the temperature of the target space (S) and the set temperature with respect to ΔMV.

[0075] The heat source unit (20) may consist of multiple chiller units (20).

[0076] The heat source unit (20) is not limited to a chiller unit and can be any unit that exchanges heat with the heat transfer medium circuit (C) of the air conditioning system (30).

[0077] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, these embodiments and modifications may be combined or substituted as appropriate, as long as they do not impair the functions of the subject matter of this disclosure. The terms “First,” “Second,” etc., used above are used to distinguish the phrases to which these terms are attached, and do not limit the number or order of such phrases. [Industrial applicability]

[0078] As explained above, this disclosure is useful for air conditioning systems. [Explanation of Symbols]

[0079] 10. Air conditioning system 20 Chiller Units (Heat Source Units) 30. Air conditioning system (utilization unit) 33 Indoor heat exchanger (heat exchanger) 34 Flow control valve 51. First water pump (first conveying section) 52. Second water pump (second conveying section) 100 Control Unit BP bypass channel C Water circuit (heat medium circuit) S Target space

Claims

1. An air conditioning system for air conditioning a target space (S), comprising a heat source unit (20) and a utilization unit (30) provided with a predetermined heat transfer medium circuit (C), The heat source unit (20) exchanges heat with the heat transfer medium of the heat transfer medium circuit (C), The utilization unit (30) includes a heat exchanger (33) connected to the heat transfer circuit (C) that exchanges heat with the air in the target space (S), and a flow control valve (34) that adjusts the flow rate of the heat transfer medium flowing through the heat exchanger (33). A first transport unit (51) for transporting the heat transfer medium, The system includes a control unit (100) that limits the upper limit of the opening degree of the flow control valve (34) based on the temperature change of the target space (S) in response to the change in the opening degree of the flow control valve (34). Air conditioning system.

2. The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) based on ΔMV, which is the amount of change in the opening degree of the flow control valve (34), and Δ(PV-SV), which is the amount of change in the difference between the temperature of the target space (S) after the change in the opening degree of the flow control valve (34) and the set temperature. The air conditioning system according to claim 1.

3. The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) based on the value of the ratio of Δ(PV-SV) to ΔMV. The air conditioning system according to claim 2.

4. The heat transfer medium circuit (C) is configured such that a plurality of the utilization units (30) are connected in parallel to the heat source unit (20). The control unit (100) limits the upper limit of the opening degree of the flow control valve (34) for each of the utilization units (30). An air conditioning system according to any one of claims 1 to 3.

5. The heat transfer fluid circuit (C) has a bypass flow path (BP) through which the heat transfer fluid flowing out from the heat source unit (20) bypasses the utilization unit (30). A second transport unit (52) for transporting the heat transfer medium is connected to the heat transfer medium circuit (C). In the heat transfer medium circuit (C), the first transport unit (51) is connected to the heat source unit (20) side via a bypass flow path (BP), and the second transport unit (52) is connected to the user unit (30) side. An air conditioning system according to any one of claims 1 to 3.

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