Air conditioning system

Abstract

Provided is an air-conditioning system which constantly flows cold / hot water to prevent freezing. An air conditioning system (10) comprising: a heat source device (4) that heats or cools water to produce cold / hot water; an air conditioner (12) that exchanges heat between the cold / hot water and air; a cold / hot water supply circuit (11) that supplies the cold / hot water to the air conditioner (12); and a control device (50) that circulates the cold / hot water in the cold / hot water supply circuit (11) so that the cold / hot water does not freeze while the air conditioner (12) is stopped. The cold / hot water supply circuit (11) has a flow rate adjustment valve (13) that adjusts the amount of cold / hot water circulating, and a fluid detector (14) that detects whether cold / hot water is flowing. When circulating cold / hot water so that the cold / hot water does not freeze while the air conditioner (12) is stopped, the controller (50) increases the opening of the flow rate adjustment valve (13) if it is detected by the fluid detector (14) that no cold / hot water is flowing.

Description

Technical Field

[0001] The present invention relates to freeze prevention control of an air conditioning system.

Background Art

[0002] As an air conditioning system, a central air conditioning system for air conditioning large facilities such as shopping malls is known. The central air conditioning system includes a heat source device that heats or cools water to make chilled and hot water, an air conditioner that exchanges heat between the chilled and hot water and air, and a chilled and hot water supply circuit that supplies chilled and hot water to the air conditioner.

[0003] In the central air conditioning system, when the outside air temperature is low, freeze prevention control is performed to prevent freezing by circulating the chilled and hot water so that the chilled and hot water in the chilled and hot water circuit does not freeze while the air conditioner is stopped (for example, Patent Document 1). In the freeze prevention control disclosed in Patent Document 1, the opening degree of the flow rate adjustment valve of the chilled and hot water is controlled so that the temperature of the chilled and hot water flowing through the chilled and hot water circuit is maintained at the freeze prevention set temperature.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Problems of the freeze prevention control of the conventional air conditioning system 110 will be described with reference to FIG. 4.

[0006] As shown in FIG. 4, in the air conditioning system 110, a plurality of air conditioners 112, 122, 132 are connected in parallel to pumps 105, boilers 106, and chillers 107 by chilled and hot water supply circuits 111, 121, 131, 141. Note that the chilled and hot water supply circuit 141 is a bypass valve having a flow rate adjustment valve 143.

[0007] For example, when one air conditioner 112 is stopped, and the remaining air conditioners 122 and 132 are in operation, and the opening degrees of the flow rate adjustment valves 123 and 133 respectively connected to the operating air conditioners 122 and 132 are fully open (100%), even if the flow rate adjustment valve 113 connected to the stopped air conditioner 112 is opened by the initial opening degree (for example, 30%) by the freezing prevention control, a large amount of chilled and warm water flows through the operating air conditioners 122 and 132, and it becomes difficult for the chilled and warm water to flow through the stopped air conditioner 112.

[0008] During the freezing prevention control of the air conditioning system 110 described above, in a situation where it is difficult for the chilled and warm water to flow through the chilled and warm water supply circuit 111, there is a risk that the chilled and warm water may freeze. At this time, it is desirable to be able to confirm whether the chilled and warm water is actually flowing through the chilled and warm water supply circuit 111 of the stopped air conditioner 112. Further, when the chilled and warm water is not flowing through the chilled and warm water supply circuit 111 of the stopped air conditioner 112, it is desirable to control to circulate the chilled and warm water.

[0009] An object of the present invention is to provide an air conditioning system capable of preventing a portion where no chilled and warm water flows.

Means for Solving the Problems

[0010] The air conditioning system according to the present invention includes a heat source device that heats or cools water to obtain chilled and warm water, an air conditioner that exchanges heat between the chilled and warm water and air, a chilled and warm water supply circuit that supplies the chilled and warm water to the air conditioner, and a control device that circulates the chilled and warm water in the chilled and warm water supply circuit so that the chilled and warm water does not freeze while the air conditioner is stopped. The chilled and warm water supply circuit has a flow rate adjustment valve that adjusts the circulation amount of the chilled and warm water and a fluid detector that detects whether the chilled and warm water is flowing. When the control device circulates the chilled and warm water so that the chilled and warm water does not freeze while the air conditioner is stopped, if the fluid detector detects that the chilled and warm water is not flowing, the control device is characterized by increasing the opening degree of the flow rate adjustment valve.

[0011] In this way, when it is detected that the chilled and warm water is not flowing, the opening degree of the valve can be increased to increase the circulation amount of the chilled and warm water and suppress the freezing of the chilled and warm water.

[0012] In the air conditioning system according to the present invention, a pump for circulating cold and warm water is further provided. When the control device detects that no cold and warm water is flowing and the opening degree of the flow rate adjustment valve is maximum, it is preferable to increase the output of the pump.

[0013] In this way, when it is detected that no cold and warm water is flowing and the valve is at the maximum opening degree, the output of the pump can be increased to increase the circulation amount of the cold and warm water and suppress the freezing of the cold and warm water.

Advantages of the Invention

[0014] According to the air conditioning system of the present invention, it is possible to prevent the occurrence of a portion where no cold and warm water is flowing. Further, when it is detected that no cold and warm water is flowing, the circulation amount of the cold and warm water can be increased to suppress the freezing of the cold and warm water.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present invention, and can be appropriately changed according to applications, purposes, specifications, etc.

[0017] An air conditioning system 10 which is an example of an embodiment will be described with reference to FIGS. 1 and 2.

[0018] The air conditioning system 10 is a central air conditioning system used for air conditioning large facilities such as shopping malls. According to the air conditioning system 10, although details will be described later, it is possible to prevent the occurrence of locations where chilled and hot water do not flow in the chilled and hot water supply circuits 11, 21, 31, and 41. Further, when it is detected that the chilled and hot water is not flowing, it is possible to increase the circulation amount of the chilled and hot water in the chilled and hot water supply circuits 11, 21, 31, and 41 to suppress the freezing of the chilled and hot water.

[0019] As shown in FIG. 1, the air conditioning system 10 includes a heat source device 4 in which a boiler 6 for heating or cooling water to chilled and hot water and a chiller 7 are provided in parallel, a pump 5 provided in series with the heat source device 4 for circulating the chilled and hot water, a plurality of chilled and hot water supply circuits 11, 21, 31, 41 provided in parallel with the heat source device 4 and the pump 5, and a control device 50 for circulating the chilled and hot water so that the chilled and hot water flowing through the chilled and hot water supply circuits 11, 21, 31, 41 does not freeze.

[0020] The heat source device 4 includes a boiler 6 for heating the chilled and hot water and a chiller 7 for cooling the chilled and hot water by an evaporative refrigeration cycle.

[0021] The pump 5 controls the circulation amount of the chilled and hot water supplied to the chilled and hot water supply circuits 11, 21, 31, 41. The electric motor driving the pump 5 has a variable frequency. Thereby, the output of the pump 5 is changed by changing the frequency of the electric motor. Note that the pump 5 may be composed of a plurality of pumps and may be configured to change the output by changing the number of operating pumps.

[0022] The chilled and hot water supply circuit 11 includes an air conditioner 12 that exchanges heat between the chilled and hot water and air, a flow rate adjustment valve 13 that adjusts the circulation amount of the chilled and hot water, and a fluid detector 14 that detects whether the chilled and hot water is flowing.

[0023] As the air conditioner 12, a fan coil unit is preferably used. The fan coil unit has an air filter for removing dust, a heat exchanger for exchanging heat between the chilled and hot water and air using the chilled and hot water as a heat source, and a blower for blowing the heat-exchanged air.

[0024] The flow rate adjustment valve 13 adjusts the flow rate (circulation volume) of the cold and hot water supply circuit 11 by increasing or decreasing the opening degree. The opening degree of the flow rate adjustment valve 13 can be adjusted from the fully closed state (0%) to the fully open state (100%).

[0025] The fluid detector 14 detects whether the cold and hot water in the cold and hot water supply circuit 11 is flowing. In this example, it is a simple fluid detector that only detects whether the cold and hot water is flowing, but it is not limited to this. A flow meter may be used to detect whether the cold and hot water in the cold and hot water supply circuit 11 is flowing.

[0026] Since the cold and hot water supply circuits 21 and 31 have the same configuration as the cold and hot water supply circuit 11, the description thereof is omitted. The cold and hot water supply circuit 41 functions as a bypass circuit without an air conditioner, and has a flow rate adjustment valve 43 that adjusts the circulation volume of the cold and hot water, and a fluid detector 44 that detects whether the cold and hot water is flowing.

[0027] The flow rate adjustment valves 23, 33, and 43 have the same configuration as the flow rate adjustment valve 13. The fluid detectors 24, 34, and 44 have the same configuration as the fluid detector 14.

[0028] Hereinafter, unless otherwise specified, the cold and hot water supply circuit 11 will be described as an example, but the same applies to the cold and hot water supply circuits 21, 31, and 41.

[0029] The control device 50 controls each device of the air conditioning system 10 and executes freeze prevention control to circulate the cold and hot water so that the cold and hot water flowing through the cold and hot water supply circuit 11 does not freeze, as described above.

[0030] The control device 50 has a CPU (Central Processing Unit) which is an arithmetic processing unit, and a storage unit such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM.

[0031] The control device 50 is connected to the pump 5, the boiler 6, the chiller 7, the air conditioner 12, the flow control valve 13, and the fluid detector 14. A signal is transmitted from the fluid detector 14, and signals are transmitted to the pump 5, the boiler 6, the chiller 7, the air conditioner 12, and the flow control valve 13.

[0032] As shown in FIG. 2, the control device 50 includes an anti-freezing control execution unit 51 that executes anti-freezing control, a flow determination unit 52 that determines whether the cold and warm water is flowing in the cold and warm water supply circuit 11, a valve opening increase unit 53 that increases the opening degree of the flow control valve 13, and a pump output increase unit 54 that increases the output of the pump 5.

[0033] When the outside air temperature is equal to or lower than a predetermined temperature (for example, 0°C) and the air conditioner 12 is stopped, the anti-freezing control execution unit 51 drives the pump 5, sets the opening degree of the flow control valve 23 to the initial opening degree (in this example, 30%), and executes anti-freezing control to circulate the cold and warm water in the cold and warm water supply circuit 11.

[0034] The flow determination unit 52 determines whether the cold and warm water in the cold and warm water supply circuit 11 is flowing by means of the fluid detector 14. Thereby, it is possible to detect the case where the cold and warm water in the cold and warm water supply circuit 11 is not flowing. If the cold and warm water is not flowing while the anti-freezing control is being executed, there is also a possibility that the cold and warm water in the cold and warm water supply circuit 11 has frozen.

[0035] When the flow determination unit 52 determines that the cold and warm water in the cold and warm water supply circuit 11 is not flowing, the valve opening increase unit 53 increases the opening degree of the flow control valve 13 by a predetermined opening degree (in this example, 10%). Thereby, the circulation amount of the cold and warm water in the cold and warm water supply circuit 11 can be increased, and the freezing of the cold and warm water can be suppressed.

[0036] When the opening degree of the flow rate adjustment valve 23 is at the maximum opening degree (100% in this example), and the flow determination unit 52 determines that the cold and warm water in the cold and warm water supply circuit 11 is not flowing, the pump output increasing unit 54 increases the output of the pump 5. Specifically, the frequency of the electric motor driving the pump 5 is increased. As a result, the circulation amount of the cold and warm water in the cold and warm water supply circuit 11 increases, and the freezing of the cold and warm water can be suppressed. When the frequency of the pump 5 reaches the upper limit frequency, the standby pump 5 may be operated.

[0037] The above describes the freezing prevention control for circulating the cold and warm water so that the cold and warm water flowing through the cold and warm water supply circuit 11 does not freeze. The same applies to the cold and warm water supply circuits 21, 31, and 41.

[0038] The flow of the freezing prevention control will be described with reference to FIG. 3.

[0039] In step S11, it is confirmed whether the freezing prevention control is being executed by the freezing prevention control execution unit 51. The freezing prevention control drives the pump 5 when the outside air temperature is 0°C or lower and the air conditioner 12 is stopped, sets the initial opening degree of the flow rate adjustment valve 13 to 30%, and circulates the cold and warm water in the cold and warm water supply circuit 11.

[0040] In step S12, the flow determination unit 52 determines whether the cold and warm water in the cold and warm water supply circuit 11 is flowing. If the cold and warm water is flowing, the freezing prevention control is executed as it is. If the cold and warm water is not flowing, the process proceeds to step S13.

[0041] In step S13, it is determined whether the opening degree of the flow rate adjustment valve 13 is at the maximum opening degree (100% in this example). If it is not at the maximum opening degree, the process proceeds to step S14. If it is at the maximum opening degree, the process proceeds to step S15.

[0042] In step S14, the valve opening increasing section 53 increases the opening of the flow rate adjustment valve 13 by 10%. Also, in step S15, the pump output increasing section 54 increases the output of the pump 5. Specifically, the frequency of the electric motor driving the pump 5 is increased by a predetermined frequency. When the frequency of the pump 5 reaches the upper limit frequency, the pump 5 that has been in operation standby may be operated.

[0043] Note that the present invention is not limited to the above-described embodiments and their modified examples, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application.

Explanation of Reference Numerals

[0044] 4 Heat source device, 5 Pump, 6 Boiler, 7 Chiller, 10 Air conditioning system, 11 Cold and hot water supply circuit, 12 Air conditioner, 13 Flow rate adjustment valve, 14 Fluid detector, 21 Cold and hot water supply circuit, 22 Air conditioner, 23 Flow rate adjustment valve, 24 Fluid detector, 31 Cold and hot water supply circuit, 32 Air conditioner, 33 Flow rate adjustment valve, 34 Fluid detector, 41 Cold and hot water supply circuit, 43 Flow rate adjustment valve, 44 Fluid detector, 50 Control device, 51 Freezing prevention control execution section, 52 Flow determination section, 53 Valve opening increasing section, 54 Pump output increasing section, 105 Pump, 106 Boiler, 107 Chiller, 110 Air conditioning system, 111 Cold and hot water supply circuit, 112 Air conditioner, 113 Flow rate adjustment valve, 121 Cold and hot water supply circuit, 122 Air conditioner, 123 Flow rate adjustment valve, 131 Cold and hot water supply circuit, 132 Air conditioner, 133 Flow rate adjustment valve, 141 Cold and hot water supply circuit

Claims

1. A heat source device that heats or cools water to produce hot and cold water, a plurality of air conditioners that exchange heat between the hot and cold water and air, a plurality of hot and cold water supply circuits that supply the hot and cold water to each of the plurality of air conditioners, and a control device that circulates the hot and cold water in the hot and cold water supply circuits so that the hot and cold water does not freeze while the air conditioners are stopped. An air conditioning system comprising: Each of the plurality of hot and cold water supply circuits has a flow rate adjustment valve that adjusts the circulation amount of the hot and cold water, and a fluid detector that detects whether the hot and cold water is flowing. When at least one of the air conditioners is operating and at least one of the air conditioners is stopped, the control device circulates the hot and cold water so that the hot and cold water in the hot and cold water supply circuit where the air conditioner is stopped does not freeze while the air conditioner is stopped. When the fluid detector in the hot and cold water supply circuit where the air conditioner is stopped detects that the hot and cold water in the hot and cold water supply circuit where the air conditioner is stopped is not flowing, the opening degree of the flow rate adjustment valve in the hot and cold water supply circuit where the air conditioner is stopped is increased. Air conditioning system.

2. The air conditioning system according to claim 1, wherein: The hot and cold water supply circuit further has a pump that circulates the hot and cold water. When the fluid detector in the hot and cold water supply circuit where the air conditioner is stopped detects that the hot and cold water is not flowing and the opening degree of the flow rate adjustment valve is maximum, the control device increases the output of the pump. Air conditioning system.

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