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 air conditioning systems. [Background technology]

[0002] The air conditioning system disclosed in Patent Document 1 takes in outside air, conditions it, and supplies it to a target space, thereby performing air conditioning such as cooling, heating, ventilation, dehumidification, and / or humidification in the target space. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-173221 Summary of the Invention [Problem to be solved by the invention]

[0004] When the operating capacity of the heat source equipment is greater than the load capacity of the air conditioner, a specified air condition is maintained. However, if the load capacity of the air conditioner becomes greater 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 of the air conditioner's flow control valve may be increased to increase the flow rate of the heat transfer medium fluid.

[0005] However, because the capacity of air conditioners is limited, even if the opening of the air conditioner's flow control valve is excessively large, the room temperature will not reach the target temperature. In this way, if fluid continues to flow through the flow control valve at an excessive opening even though the room temperature cannot reach the target temperature, the load on the pump transporting the fluid will increase and the COP of the heat source equipment will deteriorate.

[0006] An object of the present disclosure is to provide an air conditioning system that achieves energy savings. [Means for solving the problem]

[0007] A first aspect of the present 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 medium circuit (C), The heat source unit (20) exchanges heat with the heat medium in the heat medium circuit (C), the utilization unit (30) includes a heat exchanger (33) connected to the heat medium circuit (C) for exchanging heat with air in the target space (S), and a flow rate control valve (34) for adjusting a flow rate of the heat medium flowing through the heat exchanger (33); a first transfer section (51) that transfers the heat transfer medium; a control unit (100) for controlling the upper limit of the opening degree of the flow rate adjusting valve (34); It is an air conditioning system.

[0008] By limiting the upper limit of the opening degree of the flow rate control valve (34), the opening degree of the flow rate 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), the measured temperature of the target space (S) is unlikely to reach the set temperature even if the flow rate control valve (34) is opened by a predetermined amount or more. Under such circumstances, even if the opening degree of the flow rate control valve (34) is increased further, the heat exchange efficiency of the heat exchanger (33) is only slightly improved, but the measured temperature does not reach the set temperature. Furthermore, the load on the first transfer section (51) increases due to the increased flow rate of the heat medium. Thus, by setting the upper limit of the opening degree of the flow rate control valve (34), the flow rate control valve (34) is prevented from opening too much even in the above-described circumstances. This prevents the load on the first transfer section (51) from increasing, and thus prevents a deterioration in the COP of the heat source unit (20). In other words, energy conservation can be achieved.

[0009] The second aspect is the first aspect, The control unit (100) limits the upper limit of the opening of the flow rate control valve (34) based on ΔMV, which is the amount of change in the opening of the flow rate 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) and the set temperature after the opening of the flow rate control valve (34) changes.

[0010] In the second aspect, the upper limit of the opening of the flow rate adjustment valve (34) can be simply limited based on the amount of change in the opening of the flow rate adjustment valve (34) and the amount of change in the difference between the measured temperature and the set temperature.

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

[0012] In the third aspect, it is possible to determine whether further opening of the flow rate adjustment valve (34) should be restricted based on the value of the ratio of Δ(PV−SV) to ΔMV.

[0013] A fourth aspect is any one of the first to third aspects, the heat 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 of the flow rate adjustment valve (34) for each of the utilization units (30).

[0014] In the fourth aspect, the upper limit of the opening degree of the flow rate adjustment valve (34) can be limited for each utilization unit (30).

[0015] The fifth aspect is the first to fourth aspects, the heat medium circuit (C) has a bypass flow path (BP) through which the heat medium flowing out of the heat source unit (20) bypasses the utilization unit (30); a second transfer section (52) for transferring the heat medium is connected to the heat medium circuit (C); In the heat medium circuit (C), the first transfer section (51) is connected to the heat source unit (20) side via a bypass flow path (BP), and the second transfer section (52) is connected to the utilization unit (30) side.

[0016] In the fifth aspect, an increase in the load on the first transfer section (51) and the second transfer section (52) can be suppressed, thereby realizing energy savings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic piping 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 in the air conditioning system. [Figure 3] FIG. 3 is a flowchart showing a control flow for the upper limit opening degree of the flow rate adjustment valve during cooling operation. [Figure 4] FIG. 4 is a flowchart showing a control flow for the upper limit opening degree of the flow rate adjustment valve during heating operation. [Figure 5] FIG. 5 is a piping diagram of an air conditioning system according to the first modification, which corresponds to FIG. [Figure 6] FIG. 6 is a schematic piping diagram of an air conditioning system according to the second modification, which corresponds to FIG. DETAILED DESCRIPTION OF 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. Furthermore, each configuration of the embodiments, modifications, other examples, etc. described below can be combined or partially substituted within the scope of the present invention.

[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) conditions a target space (S) within a building such as a building, factory, warehouse, public facility, etc. The air conditioning system (10) takes in and treats outside air, and then supplies the treated air to the target space (S).

[0020] The air conditioning system (10) mainly includes a chiller unit (20), an air conditioner (30), and a control unit (100). The chiller unit (20) includes a refrigerant circuit (R). The air conditioner (30) includes a water circuit (C). The chiller unit (20) exchanges heat with water, which serves as a heat medium in the water circuit (C). The heat exchange between the refrigerant in the refrigerant circuit (R) and the water in the water circuit (C) cools or heats 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), the water heat exchanger (22), the expansion valve (23), the heat source heat exchanger (24), and the 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 radiator.

[0023] The compressor (21) compresses the drawn refrigerant to a high pressure and discharges it. The compressor (21) is a variable capacity compressor. The compressor (21) has a volumetric compression element, such as a scroll type, which is rotationally driven by a motor. The frequency of the motor is controlled by an inverter, thereby controlling 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 whose opening degree can be controlled.

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

[0026] The heat source fan (26) transports outdoor air to the heat source heat exchanger (24). The heat source fan (26) is controlled to vary the airflow rate.

[0027] The four-way switching valve (25) switches the flow of the refrigerant circuit (R). The four-way switching valve (25) has four connection ports, which are connected to the suction pipe and discharge pipe 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). Specifically, the four-way switching valve (25) is switchable between a first state and a second state. In the first state, the gas side of the refrigerant flow path of the water heat exchanger (22) is connected to the suction pipe of the compressor (21) and the discharge pipe of the compressor (21) is connected to the gas side of the outdoor heat exchanger (33) (solid lines in FIG. 1 for the four-way switching valve (25)). The second state is a state in which the discharge pipe of the compressor (21) communicates with the gas side of the refrigerant flow path of the water heat exchanger (22) and the gas side of the outdoor heat exchanger (33) communicates with the suction pipe of the compressor (21) (indicated by the dashed line of the four-way selector valve (25) in FIG. 1). The four-way selector 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 flow path (22a) communicating with the water circuit (C) and a refrigerant flow path (22b) communicating with the refrigerant circuit (R). The water in the water flow path (22a) exchanges heat with the refrigerant passing through the refrigerant flow path (22b) and is thereby heated or cooled.

[0029] The first water pump (51) is an example of a first transfer section (51). The first water pump (51) is connected to the water circuit (C). The first water pump (51) transfers water from the water circuit (C). The first water pump (51) is driven by a motor, and the rotation speed of the motor is adjusted by inverter control.

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

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

[0032] The supply fan (35) transports the taken-in outside air to the target space (S). For example, the air conditioner (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 treated in the air conditioner (30) and then blown out into the target space (S) through the duct. The supply fan (35) is configured to have an adjustable airflow rate.

[0033] The flow rate control valve (34) controls the flow rate of water flowing through the indoor heat exchanger (33). The flow rate control valve (34) is an electrically operated valve whose opening is adjustable. The flow rate control valve (34) adjusts the opening of the water pipes constituting the water circuit (C).

[0034] (2) Temperature sensor The air conditioner (30) has 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 in the target space (S). The second temperature sensor (42) detects the temperature of air blown out of the air conditioner (30) into the target space (S). The third temperature sensor (43) detects the intake temperature of outside air drawn into the air conditioner (30). The water temperature sensor (44) detects the temperature of water in the water circuit (C) flowing out of the water heat exchanger (22).

[0035] (3) Control Unit As shown in Fig. 2, the control unit (100) is composed of a 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 conditioner (30). The first control unit (101) and the second control unit (102) may be connected to each other so that they can communicate with each other.

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

[0037] The second control section (102) is connected to various devices of the air conditioner (30). The second control section (102) controls the operations of the flow rate adjustment valve (34), the air supply fan (35), and the like.

[0038] (4) Air conditioning system operation During operation of the air conditioning system (10), the first water pump (51) is driven to circulate water in the water circuit (C). The compressor (21) is driven to circulate refrigerant in the refrigerant circuit (R). The air conditioning system (10) performs a cooling operation and a heating operation. The cooling operation is a first refrigeration cycle operation. The heating operation is a 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 flow path (22b) in the water heat exchanger (22). The water cooled or heated in the water heat exchanger (22) flows into the air conditioner (30) and is heated or cooled by exchanging heat with outdoor 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 for cooling the air in the target space (S). In the refrigerant circuit (R), the refrigerant is compressed in the compressor (21) and discharged as a high-pressure refrigerant. The high-pressure refrigerant discharged from the compressor (21) condenses or releases heat in the heat-source heat exchanger (24) by exchanging heat with air transported by the heat-source fan (26). The refrigerant that has passed through the heat-source heat exchanger (24) is reduced in pressure in the expansion valve (23) to become a low-pressure refrigerant, and then flows into the water heat exchanger (22). The low-pressure refrigerant that has flowed into the water heat exchanger (22) evaporates by exchanging heat with water flowing through the water circuit (C). The low-pressure refrigerant that has passed through the water heat exchanger (22) is sucked back into the compressor (21).

[0041] The water in the water circuit (C) is cooled in the water heat exchanger (22) to a target water temperature. After exchanging heat with the refrigerant in the water heat exchanger (22), the water in the water circuit (C) is heated in the indoor heat exchanger (33) by exchanging heat with outside air taken in through an inlet by the air supply fan (35). The outside air that has exchanged heat in the indoor heat exchanger (33) is cooled and blown out through an outlet of the air conditioner (30) into the target space (S). 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 for heating the air in the target space (S). In the heating operation, the refrigerant is compressed in the compressor (21) and discharged as a 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). The refrigerant that has passed through the water heat exchanger (22) is reduced in pressure in the expansion valve (23) to become a low-pressure refrigerant, and then flows into the outdoor heat exchanger (33). The low-pressure refrigerant that has flowed into the outdoor heat exchanger (33) evaporates by exchanging heat with air transported by the heat source fan (26). The low-pressure refrigerant that has passed through the outdoor heat exchanger (33) is sucked back into the compressor (21).

[0043] The water in the water circuit (C) is heated in the water heat exchanger (22) to a target water temperature. After exchanging heat with the refrigerant in the water heat exchanger (22), the water in the water circuit (C) is cooled in the indoor heat exchanger (33) by exchanging heat with outside air taken in through an inlet by the air supply fan (35). The outside air that has exchanged heat in the indoor heat exchanger (33) is heated and blown out through an outlet of the air conditioner (30) into the target space (S). This increases the indoor air temperature in the target space (S) to the target temperature.

[0044] (5) Issues when air conditioning load becomes excessive The air conditioning unit that conditions the target space adjusts the opening of the flow control valve based on the difference between the air condition (dry bulb temperature, relative humidity, etc.) (current value) of the target space (S) and the preset air condition (target value), and controls it to maintain the preset air condition (target value).

[0045] In a central air conditioner, when the operating capacity of the chiller unit is greater than the load capacity of the air conditioner, the specified air quality is maintained. However, if the load capacity of the air conditioner exceeds the operating capacity of the chiller unit due to a change in the air conditioning load in the target space, the air conditioner's flow control valve cannot maintain the preset air quality (target value), so the flow control valve opens excessively, and in some cases, opens to its maximum opening. In cases where the air conditioner's design is affected by increased air conditioning load due to recent global warming or increased load on production facilities, the air conditioner's capacity is naturally limited, and even if the flow control valve opens excessively, the specified air quality cannot be maintained. In other words, even if the flow control valve opens excessively, it is controlled toward a target value that cannot be reached.

[0046] In conventional control, the flow control valve is controlled based on the difference between the current value and the target value of the target air, which can lead to a deterioration in COP due to partial load operation of the heat source and wasteful use of power in the transport system such as pumps.

[0047] To address this issue, the air conditioning system (10) of the present disclosure includes a control unit (100) that controls the upper limit of the opening degree of the flow rate control valve (34). The control unit (100) limits the upper limit of the opening degree of the flow rate control valve (34) when a predetermined condition is met. The predetermined condition is met, for example, when the air conditioning load of the target space (S) exceeds the cooling capacity of the air conditioner (30). The predetermined condition is also met, for example, when the load capacity of the air conditioner (30) exceeds the operating capacity of the chiller unit (20). In the air conditioning system (10) of the present disclosure, when such a condition is met, the flow rate control valve (34) is prevented from opening excessively, and the water pump is prevented from operating excessively. As a result, an increase in power consumption and a deterioration in 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 of the flow rate control valve (34) based on ΔMV, which is the amount of change in the opening of the flow rate 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) and the set temperature after the opening of the flow rate control valve (34) has changed. PV indicates the current air temperature of the target space (S). The air temperature of the target space (S) is based on a value measured by the second temperature sensor (42). The air temperature of the target space (S) may also be based on a value measured by the first temperature sensor (41). SV indicates a target air temperature of the target space. The SV is the set temperature of the target space (S). MV indicates a control output value (%) output to the flow rate control valve (34). When MV is 100%, the flow rate control valve (34) is fully open, and when MV is 0%, the flow rate control valve (34) is fully closed. The control unit (100) below may be a first control unit (101) or a second control unit (102).

[0049] 3 and 4, the upper limit control of the opening degree of the flow rate control valve (34) for each of the cooling operation (air-conditioning operation) and the heating operation (heating operation). A1, A2, B1, B2, C1, C2, D1, D2, E1, E2, OH1, and OH2 shown below are each arbitrary values, and are set by the user, for example.

[0050] (6-1) Cooling operation In step S11, the control section (100) determines whether the flow rate adjustment valve (34) is at or above a predetermined opening. Specifically, the control section (100) determines whether the MV is at or above a predetermined value (A1%). If it is determined that the MV is at or above 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 section (100) determines whether Δ(PV−SV), which is the difference between PV and SV, is equal to or greater than a predetermined value (B1). If it is determined that Δ(PV−SV) is equal to or greater than 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 section (100) determines whether the value of Δ(PV−SV) relative to ΔMV (Δ(PV−SV) / ΔMV) is equal to or greater than a predetermined value (C1). If it is determined that Δ(PV−SV) / ΔMV is equal to or greater than 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 fixed change in opening degree (e.g., +5%).

[0053] In step S14, the control unit (100) limits the opening of the flow rate adjustment valve (34). In this embodiment, the upper limit output value (OH1) is limited in the control unit (100) with the opening MV+D1 (predetermined value) at the time of determination in step S13 as the upper limit. This prevents the opening of the flow rate adjustment valve (34) from exceeding the opening 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 equal to or greater than E1 (YES in step S15), step S16 is executed. If it is determined that the difference between OH1 and MV is smaller than E1 (NO in step S15), step S15 is executed again.

[0055] In step S16, the control section (100) cancels the restriction on the opening degree of the flow rate adjustment valve (34) in step S14.

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

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

[0058] In step S22, the control section (100) determines whether Δ(SV-PV), which is the difference between SV and PV, is equal to or greater than a predetermined value (B2). If it is determined that Δ(SV-PV) is equal to or greater than 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 section (100) determines whether the value of Δ(SV-PV) relative to ΔMV (Δ(SV-PV) / ΔMV) is equal to or greater than a predetermined value (C2). If it is determined that Δ(SV-PV) / ΔMV is equal to or greater than 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 fixed change in opening degree (for example, +5%).

[0060] In step S24, the control unit (100) limits the opening of the flow rate adjustment valve (34). In this embodiment, the upper limit of the opening MV+D2 (predetermined value) at the time of determination in step S23 is set as the upper limit, and an upper limit output value (OH2) is output to the flow rate adjustment valve (34). As a result, the opening of the flow rate adjustment valve (34) does not exceed the opening 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 equal to or greater than E2 (YES in step S25), step S26 is executed. If it is determined that the difference between OH2 and MV is smaller than E2 (NO in step S25), step S25 is executed again.

[0062] In step S26, the control section (100) cancels the restriction on the opening degree of the flow rate adjustment valve (34) in step S24.

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

[0064] (7) Features (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 opening degree of the flow control valve (34) from reaching its maximum opening degree. By setting the upper limit of the opening degree of the flow control valve (34) in this manner, the flow control valve (34) is prevented from opening too much even when, for example, the air conditioning load exceeds the design capacity of the heat exchanger (33). As a result, an increase in the load on the first water pump (51) is suppressed, and a deterioration in the COP of the heat source unit (20) is suppressed. In other words, energy conservation can be achieved.

[0065] (7-2) Feature 2 The air conditioning system (10) of this embodiment limits the upper limit of the opening of the flow rate control valve (34) based on ΔMV, which is the amount of change in the opening of the flow rate 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) and the set temperature after the opening of the flow rate control valve (34) has changed. This makes it possible to simply limit the upper limit of the opening of the flow rate control valve (34) based on the amount of change in the opening of the flow rate control valve (34) and the amount of 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 rate adjustment valve (34) based on the ratio of Δ(PV-SV) to ΔMV. In this way, it is possible to determine whether further opening of the flow rate adjustment valve (34) should be limited based on the ratio of Δ(PV-SV) to ΔMV.

[0067] (8) Variation 1 As shown in Fig. 5, the air conditioning system (10) may include a plurality of air conditioners (30). An air conditioner (30) is provided in each of 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 conditioner (30). The control unit (100) executes the control flow of the above embodiment for each air conditioner (30).

[0068] (9) Variation 2 6, the air conditioning system (10) of the second modification has a bypass flow path (BP) provided in the water circuit (C). In the bypass flow path (BP), water that has exchanged heat in the water heat exchanger (22) bypasses the air conditioner (30). The water circuit (C) of the second modification has, on either side of the bypass flow path (BP), a primary water circuit (C1) connected to the chiller unit (20) and a secondary water circuit (C2) connected to the air conditioner (30).

[0069] The air conditioning system (10) has a second water pump (52) that transports water in the water circuit (C). The second water pump (52) is an example of a second transfer section (52). The operation of the second water pump (52) is controlled by the control section (100). In the water circuit (C), a 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 conditioner (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 in the primary water circuit (C1), and the second water pump (52) transports water in the secondary water circuit (C2).

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

[0071] However, when 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 conditioner (30) is opened excessively, resulting in the problem described in the above embodiment. Specifically, the flow rate of water flowing through the secondary water circuit (C2) to which the air conditioner (30) is connected increases excessively, and the flow rate of water flowing through the primary water circuit (C1) to which the chiller unit (20) is provided becomes insufficient.

[0072] That is, the cold water that has been heat exchanged in the chiller unit (20) and a part of the excess water that has been heated in the secondary water circuit (C2) join together in the bypass flow path (BP), causing the temperature of the water conveyed to the secondary water circuit (C2) to rise, 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 become even larger. This causes excessive operating loads on the first water pump (51) and the second water pump (52), making it impossible to prevent an increase in power consumption and a deterioration in 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, preventing the flow rate control valve (34) from reaching a fully open state, and thus allowing water to flow to the air conditioner (30) at a flow rate equivalent to the load. Because the air condition in the target space (S) has not yet reached the set state, the air conditioner (30) outputs a flow rate request equivalent to the load. The chiller unit (20) remains temporarily unable to keep up with the load. However, the amount of water in the secondary water circuit (C2) is prevented from becoming excessive. As a result, water heated by the air conditioner (30) is prevented from flowing into the bypass flow path (BP) and merging with water cooled in the primary water circuit (C1). This limits the time delay due to load-up of the chiller unit (20), thereby preventing a temperature rise in the water transported from the primary water circuit (C1) to the secondary water circuit (C2).

[0074] (10) Other embodiments In the above embodiment and each modification, the upper limit control of the opening degree of the flow rate adjustment valve (34) may be performed without steps S11 and S21. That is, the control unit (100) may perform the upper limit control of the opening degree of the flow rate adjustment valve (34) based only on the value of Δ(PV-SV), which is the difference in the amount of change in the difference between the temperature of the target space (S) and the set temperature relative to ΔMV.

[0075] The heat source unit (20) may be composed of a plurality of chiller units (20).

[0076] The heat source unit (20) is not limited to a chiller unit as long as it is a unit that exchanges heat with the heat medium circuit (C) of the air conditioner (30).

[0077] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and detail are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate as long as the functionality of the subject matter of this disclosure is not impaired. The terms "first," "second," etc., described above, are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0078] As described above, the present disclosure is useful for air conditioning systems. [Explanation of symbols]

[0079] 10. Air Conditioning System 20 Chiller unit (heat source unit) 30 Air conditioning unit (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 section BP bypass flow path 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 medium circuit (C), The heat source unit (20) exchanges heat with the heat medium in the heat medium circuit (C), the utilization unit (30) includes a heat exchanger (33) connected to the heat medium circuit (C) for exchanging heat with air in the target space (S), and a flow rate control valve (34) for adjusting the flow rate of the heat medium flowing through the heat exchanger (33); a first transfer section (51) that transfers the heat medium; a control unit (100) that limits the upper limit of the opening degree of the flow rate adjustment valve (34). Air conditioning system.

2. The control unit (100) limits the upper limit of the opening degree of the flow rate control valve (34) based on ΔMV, which is the amount of change in the opening degree of the flow rate 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) and the set temperature after the opening degree of the flow rate control valve (34) has changed. The air conditioning system of claim 1 .

3. The control section (100) limits the upper limit of the opening degree of the flow rate adjustment valve (34) based on the value of the ratio of Δ(PV−SV) to ΔMV.

3. The air conditioning system of claim 2.

4. the heat 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 section (100) limits the upper limit of the opening of the flow rate adjustment 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 medium circuit (C) has a bypass flow path (BP) through which the heat medium flowing out of the heat source unit (20) bypasses the utilization unit (30); A second transfer section (52) for transferring the heat medium is connected to the heat medium circuit (C), In the heat medium circuit (C), the first transfer section (51) is connected to the heat source unit (20) side via a bypass flow path (BP), and the second transfer section (52) is connected to the utilization unit (30) side. An air conditioning system according to any one of claims 1 to 3.

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