JP7706563B2 - Air Conditioning System - Google Patents

Description

The present invention relates to anti-freeze control for air conditioning systems.

A well-known example of an air conditioning system is a central air conditioning system that provides air conditioning to large facilities such as shopping malls. A central air conditioning system includes a heat source device that heats or cools water to produce cold or hot water, an air conditioner that exchanges heat between the cold or hot water and air, and a cold or hot water supply circuit that supplies cold or hot water to the air conditioner.

In central air conditioning systems, when the outside temperature is low, anti-freeze control is performed to circulate the cold and hot water in the cold and hot water circuit to prevent freezing while the air conditioner is stopped (for example, Patent Document 1). The anti-freeze control disclosed in Patent Document 1 controls the opening of the cold and hot water flow adjustment valve so that the temperature of the cold and hot water flowing through the cold and hot water circuit is maintained at the anti-freeze set temperature.

JP 2009-216321 A

Using Figure 4, we will explain the issues with anti-freeze control in the conventional air conditioning system 110.

As shown in Figure 4, in the air conditioning system 110, multiple air conditioners 112, 122, 132 are connected in parallel to the pump 105, boiler 106, and chiller 107 by hot and cold water supply circuits 111, 121, 131, and 141. The hot and cold water supply circuit 141 is a bypass valve having a flow control valve 143.

For example, when one air conditioner 112 is stopped and the remaining air conditioners 122, 132 are operating, and the flow control valves 123, 133 connected to the operating air conditioners 122, 132 are fully open (100%), even if the flow control valve 113 connected to the stopped air conditioner 112 is only opened to its initial opening (e.g., 30%) due to anti-freeze control, a lot of cold or hot water will flow to the operating air conditioners 122, 132, and it will be difficult for cold or hot water to flow to the stopped air conditioner 112.

In a situation where cold or hot water does not flow easily through the cold or hot water supply circuit 111 during the above-mentioned anti-freeze control of the air conditioning system 110, there is a risk that the cold or hot water will freeze. At this time, it is desirable to be able to confirm whether cold or hot water is actually flowing through the cold or hot water supply circuit 111 of the stopped air conditioner 112. Also, if cold or hot water is not flowing through the cold or hot water supply circuit 111 of the stopped air conditioner 112, it is desirable to control the cold or hot water to circulate.

The object of the present invention is to provide an air conditioning system that can prevent any area from not having hot or cold water flowing.

The air conditioning system of the present invention is an air conditioning system including a heat source device that heats or cools water to produce cold and hot water, an air conditioner that exchanges heat between the cold and hot water and air, a cold and hot water supply circuit that supplies cold and hot water to the air conditioner, and a control device that circulates the cold and hot water in the cold and hot water supply circuit to prevent the cold and hot water from freezing while the air conditioner is stopped, the cold and hot water supply circuit has a flow control valve that adjusts the amount of cold and hot water circulated, and a fluid detector that detects whether cold and hot water is flowing, and the control device is characterized in that when circulating cold and hot water to prevent the cold and hot water from freezing while the air conditioner is stopped, if the fluid detector detects that cold and hot water is not flowing, the control device increases the opening of the flow control valve.

In this way, when it is detected that cold or hot water is not flowing, the valve opening is increased to increase the amount of cold or hot water circulating, thereby preventing the cold or hot water from freezing.

In the air conditioning system of the present invention, it is preferable that the system further includes a pump for circulating cold and hot water, and the control device increases the output of the pump when the flow detector detects that cold and hot water is not flowing and the opening of the flow control valve is at its maximum.

In this way, when it is detected that cold or hot water is not flowing and the valve is at its maximum opening, the pump output is increased to increase the amount of cold or hot water circulating, thereby preventing the cold or hot water from freezing.

The air conditioning system of the present invention can prevent the occurrence of areas where cold and hot water is not flowing. Furthermore, when it is detected that cold and hot water is not flowing, the amount of cold and hot water circulated can be increased to prevent the cold and hot water from freezing.

1 is a schematic diagram illustrating an air conditioning system according to an embodiment; 1 is a block diagram showing a control configuration of an air conditioning system according to an embodiment; FIG. 4 is a flow chart showing a flow of anti-freezing control. FIG. 1 is a schematic diagram showing anti-freeze control of a conventional air conditioning system.

The following is a detailed description of an embodiment of the present invention. In the following description, specific shapes, materials, directions, values, etc. are examples to facilitate understanding of the present invention, and can be modified as appropriate according to the application, purpose, specifications, etc.

Using Figures 1 and 2, we will explain the air conditioning system 10, which is an example of an embodiment.

The air conditioning system 10 is a central air conditioning system used to air condition large facilities such as shopping malls. As will be described in detail later, the air conditioning system 10 can prevent any location in the cold/hot water supply circuits 11, 21, 31, 41 from not flowing with cold/hot water. Furthermore, when it is detected that cold/hot water is not flowing, the amount of cold/hot water circulating in the cold/hot water supply circuits 11, 21, 31, 41 can be increased to prevent the cold/hot water from freezing.

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

The heat source device 4 includes a boiler 6 that heats cold and hot water, and a chiller 7 that cools the cold and hot water using an evaporative refrigeration cycle.

Pump 5 controls the circulation amount of cold and hot water supplied to cold and hot water supply circuits 11, 21, 31, 41. The electric motor driving pump 5 has a variable frequency. Thus, the output of pump 5 is changed by changing the frequency of the electric motor. Pump 5 may be configured to be composed of multiple pumps, and the output may be changed by changing the number of pumps in operation.

The cold and hot water supply circuit 11 has an air conditioner 12 that exchanges heat between the cold and hot water and air, a flow control valve 13 that adjusts the amount of cold and hot water circulating, and a fluid detector 14 that detects whether the cold and hot water is flowing.

A fan coil unit is preferably used as the air conditioner 12. The fan coil unit has an air filter that removes dust, a heat exchanger that exchanges heat with air using hot and cold water as a heat source, and a blower that blows the air that has been heat exchanged.

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

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

The cold and hot water supply circuits 21 and 31 have the same configuration as the cold and hot water supply circuit 11, so their explanations are omitted. The cold and hot water supply circuit 41 functions as a bypass circuit without an air conditioner, and has a flow control valve 43 that adjusts the amount of cold and hot water circulating, and a fluid detector 44 that detects whether cold and hot water is flowing.

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

Unless otherwise specified, the following description focuses on the cold and hot water supply circuit 11, but the same applies to the cold and hot water supply circuits 21, 31, and 41.

The control device 50 controls each device in the air conditioning system 10 and also performs anti-freeze control to circulate the cold and hot water flowing through the cold and hot water supply circuit 11 so that it does not freeze, as described above.

The control device 50 has a central processing unit (CPU) which is an arithmetic processing unit, and memory units such as a random access memory (RAM) and a read only memory (ROM), and performs signal processing according to a program pre-stored in the ROM while utilizing the temporary storage function of the RAM.

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

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

If the outside air temperature is below a predetermined temperature (e.g., 0°C) and the air conditioner 12 is stopped, the anti-freeze control execution unit 51 drives the pump 5, sets the opening of the flow control valve 23 to its initial opening (30% in this example), and executes anti-freeze control to circulate the cold and hot water in the cold and hot water supply circuit 11.

The flow determination unit 52 uses the fluid detector 14 to determine whether or not cold or hot water is flowing in the cold or hot water supply circuit 11. This makes it possible to detect when cold or hot water is not flowing in the cold or hot water supply circuit 11. If cold or hot water is not flowing while anti-freeze control is being executed, the cold or hot water in the cold or hot water supply circuit 11 may be frozen.

When the flow determination unit 52 determines that the cold/hot water supply circuit 11 is not flowing, the valve opening increase unit 53 increases the opening of the flow control valve 13 by a predetermined opening (10% in this example). This increases the amount of cold/hot water circulating in the cold/hot water supply circuit 11, making it possible to prevent the cold/hot water from freezing.

The pump output increase unit 54 increases the output of the pump 5 when the flow determination unit 52 determines that cold or hot water is not flowing in the cold or hot water supply circuit 11, even if the flow control valve 23 is at its maximum opening (100% in this example). Specifically, it increases the frequency of the motor that drives the pump 5. This increases the amount of circulation in the cold or hot water supply circuit 11, making it possible to prevent the cold or hot water from freezing. Note that when the frequency of the pump 5 is at the upper limit frequency, the pump 5 that is in standby may be operated.

The above describes the anti-freeze control that circulates cold and hot water so that the cold and hot water flowing through the cold and hot water supply circuit 11 does not freeze, but the same applies to the cold and hot water supply circuits 21, 31, and 41.

Using Figure 3, the flow of anti-freeze control will be explained.

In step S11, it is confirmed whether anti-freeze control is being executed by the anti-freeze control execution unit 51. If the outside air temperature is below 0°C and the air conditioner 12 is stopped, the anti-freeze control drives the pump 5, sets the initial opening of the flow control valve 13 to 30%, and circulates the cold and hot water in the cold and hot water supply circuit 11.

In step S12, the flow determination unit 52 determines whether or not cold or hot water is flowing in the cold or hot water supply circuit 11. If cold or hot water is flowing, the anti-freeze control is executed. If cold or hot water is not flowing, the process proceeds to step S13.

In step S13, it is determined whether the flow control valve 13 is at its maximum opening (100% in this example). If it is not at its maximum opening, the process proceeds to step S14. If it is at its maximum opening, the process proceeds to step S15.

In step S14, the valve opening increase unit 53 increases the opening of the flow control valve 13 by 10%. In addition, in step S15, the pump output increase unit 54 increases the output of the pump 5. Specifically, the frequency of the motor that drives the pump 5 is increased by a predetermined frequency. Note that if the frequency of the pump 5 is the upper limit frequency, the pump 5 that is on standby may be operated.

It should be understood that the present invention is not limited to the above-described embodiments and their variations, and that various modifications and improvements are possible within the scope of the matters described in the claims of this application.

4 Heat source device, 5 Pump, 6 Boiler, 7 Chiller, 10 Air conditioning system, 11 Chilled/hot water supply circuit, 12 Air conditioner, 13 Flow rate control valve, 14 Fluid detector, 21 Chilled/hot water supply circuit, 22 Air conditioner, 23 Flow rate control valve, 24 Fluid detector, 31 Chilled/hot water supply circuit, 32 Air conditioner, 33 Flow rate control valve, 34 Fluid detector, 41 Chilled/hot water supply circuit, 43 Flow rate control valve, 44 Fluid detector, 50 Control device, 51 Anti-freeze control execution unit, 52 Flow determination unit, 53 Valve opening degree increase unit, 54 Pump output increase unit, 105 Pump, 106 Boiler, 107 Chiller, 110 Air conditioning system, 111 Chilled/hot water supply circuit, 112 Air conditioner, 113 Flow rate control valve, 121 Chilled/hot water supply circuit, 122 Air conditioner, 123 flow rate control valve, 131 cold/hot water supply circuit, 132 air conditioner, 133 flow rate control valve, 141 cold/hot water supply circuit

Claims (2)

An air conditioning system including a heat source device that heats or cools water to produce cold and hot water, a plurality of air conditioners that exchange heat between the cold and hot water and air, a plurality of cold and hot water supply circuits that supply the cold and hot water to each of the plurality of air conditioners, and a control device that circulates the cold and hot water in the cold and hot water supply circuits so that the cold and hot water does not freeze while the air conditioners are stopped,
Each of the plurality of cold and hot water supply circuits has a flow rate regulating valve that regulates a circulation amount of the cold and hot water, and a fluid detector that detects whether the cold and hot 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 cold/hot water in the cold/hot water supply circuit in which the air conditioner is stopped so that the cold/hot water does not freeze while the air conditioner is stopped, and when the fluid detector in the cold/hot water supply circuit in which the air conditioner is stopped detects that the cold/hot water is not flowing in the cold/hot water supply circuit in which the air conditioner is stopped , the control device increases the opening degree of the flow rate adjustment valve in the cold/hot water supply circuit in which the air conditioner is stopped .
Air conditioning system. 2. The air conditioning system according to claim 1,
The hot and cold water supply circuit further includes a pump that circulates the hot and cold water,
the control device increases the output of the pump when the flow detector of the cold/hot water supply circuit detects that the cold/hot water is not flowing and the opening degree of the flow rate regulating valve is maximum while the air conditioner is stopped ;
Air conditioning system.

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