JPH04208332A - Air conditioner having cold water making circuit - Google Patents

Abstract

PURPOSE:To perform an operation of high energy saving corresponding to a surrounding air condition by a method wherein a single operation or a parallel operation of a cooling tower or a freezer is carried out under a condition in which the cooling tower is preferentially controlled in response to a result of judgment of a surrounding air wet ball temperature. CONSTITUTION:A surrounding air wet ball temperature T4 is inputted and a moving mean value during that 30 minutes is calculated. Concurrently, a cold water temperature T4 is inputted, a moving means value during 30 minutes is calculated and a variation transmittance is estimated. Then, in the case that a mean value of the surrounding air wet ball temperature is 7 deg.C or lower and a mean value of the surrounding cold air is in a range of 10 deg.C to 12 deg.C and the cold water temperature is apt to be decreased, it becomes possible to utilize the surrounding cold air, resulting in that a freezer 101 is stopped and the operation is changed over to a system of the cooling tower 102. In turn, in the case that a mean value of the surrounding air wet ball temperature is 7 deg.C or higher and a mean value of the cold water temperature of a calculated value is apt to be increased, the operation of the cooling tower is stopped and the operation is changed over to that of the freezer 101. In the case that a mean value of the cold water temperature is to be decreased, the operation state up to now is kept.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention aims to reduce the cooling operating costs of rooms that require cooling throughout the year, such as computer rooms and synthetic fiber manufacturing facilities. Regarding air conditioners that can be used.

(Conventional technology) Refrigerators are used even in winter in rooms where it is difficult to control the target temperature and humidity with outside air cooling alone, such as in rolling and twisting rooms in synthetic fiber manufacturing, where internal heat generation is large even in winter and relative humidity is kept constant. Do I need to run the car to cool it down?

For this reason, from the perspective of energy conservation, a method has been proposed in which cold water is produced in a cooling tower using outside air without operating the refrigerator in winter, and this is used for air conditioning.

The air conditioner with one chilled water production circuit disclosed in Japanese Patent Application Laid-Open No. 61-128042 shown in Figs. 3 and 4 is a system that adds a chilled water coil and a chilled water switching valve to the previously proposed air conditioning system. Fig. 3 shows an example of an improved system which performs cold water cooling by passing cold water from a cooling tower through a cold water coil in an air conditioner when the outside air is cold.

In the figure, this air conditioning system includes a refrigerator 101.
Two cold/heat source circuits each including 201 are provided. The cooling water side circuit of the first system includes a cooling tower 102 and a three-way valve 1.
31 and a pump 157, and the cooling water side circuit of the second system includes a cooling tower 202, a three-way valve 232, a pump 258, and switching valves 224 and 225. Open cooling tower I02
If a closed type cooling tower (see Figure 4) is used instead of the 202, an expansion tank is attached to the system. The cold water side circuit includes an air machine 15, an expansion tank 16, a pump 159.260,
The switching valve 123 is included, and the attached bypass circuits 217 and 218 include switching valves 221 + 22, respectively.
Contains 2 or more. Also, to control the entire air conditioning system, temperature sensors T,, T2. T2.
T, and a pressure regulator 41.42°4.3.44 are provided. The symbol WB indicates the outside air wet bulb temperature.

Based on this configuration, normal cooling operation is performed during the summer. That is, the switching valves 221 + 222 are closed to stop the flow in the bypass circuits 217 and 218, and the switching valves 123, 224, and 225 are opened to shut off the flow in the two refrigerators 10'l.
, 201 are operated simultaneously, and the cooling water side circuit of the first system and the cooling water side circuit of the second system are operated independently.

When the transition from summer to winter occurs, the switching valve 123.22
By closing switching valves 221 and 222 and opening bypass circuit 2]7.2]8, the cold water side circuit of the first system is connected in series with the cooling water side circuit of the second system. Connect to. This completes a cold water production circuit using a cooling tower.

In the second cold water production circuit, the cooling tower is operated with priority over the refrigerator, and the following two types of operation are performed. That is, (I) the free cooling cooling tower 20 is operated, and the refrigerator 101° 201 and the cooling tower 201 are stopped. Energy-saving operation when the cooling load is small.

(II) Series operation Cooling tower 202, refrigeration [101] and cooling tower 102 are operated, and refrigerator 201 is stopped. When the cooling load is moderate, it is a light-saving, low-speed operation.

(Problem to be solved by the invention) However, the second method of producing cold water had the following problems. First, when transitioning from summer to winter, switch valves 123 + 221 + 2 & 2 to stop the refrigerator and operate the chilled water production system using a cooling tower. If there is a significant temperature change, the refrigerator must be operated, making it difficult to determine when to switch the valve.

Second, valve l 43 + :221 + 224
Switching is complicated, and in order to save labor, it is necessary to use an electric valve or an automatic pneumatic valve, which would require a large amount of equipment cost.

The present invention was devised in view of the above-mentioned problems. It does not require complicated control, allows stable cooling operation to continue without being affected by sudden temperature changes, and is responsive to outside temperature conditions. An object of the present invention is to provide an air conditioner that can operate efficiently and save energy in cooling operation.

(Means for Solving the Problem) The above purpose is to provide an air conditioner equipped with two chilled water production circuits, using the chilled water side circuit of the refrigerator in the first system and the outside air in the second system. A cold water side circuit using only a cooling tower,
A buffer tank that stores the cold water produced in these cold water production circuits and a switching device that switches the connection between this buffer tank and the two cold water side circuits are provided, and the cold water in the stored buffer tank is transferred to the air conditioner. This is achieved by an air conditioner having a cold water production circuit characterized by performing air conditioning by circulating cold water to the cold water coils.

In addition, the switching device detects the cold water temperature of the buffer tank and the outside air wet bulb temperature, causes the cooling tower to operate preferentially to the refrigerator, and changes the operation mode as the outside air wet bulb temperature becomes lower (i) as the first stage. Operation with only the cold water side circuit of the refrigerator of the first system, (ii) Parallel operation with the cold water side circuit by a cooling tower using outside air of the first system and the second system as a second stage, (ii) As the third step, by sequentially switching to operation using only the cold water side circuit using the cooling tower, it is possible to switch to an efficient operation mode according to the outside temperature and humidity conditions, and achieve efficient energy savings.

(Function) As described above, this air conditioner is equipped with two cold water production circuits: the cold water side circuit of the 10th system refrigerator and the cold water side circuit using only the second cooling tower, and these can be switched as appropriate. Furthermore, a buffer tank is provided in the cold water circulation circuit that performs heat exchange by supplying the produced cold water to a cooling coil provided in the room to be air-conditioned.

As a result, even if there is a sudden or sudden temperature change in the outside air during operation using outside air energy by the cooling tower, the fluctuation is absorbed by the cold water stored in the buffer tank, resulting in stable operation. It is possible to control the temperature.

In addition, under the condition that the cooling tower is controlled preferentially, the chiller and the cooling tower can be operated individually or in parallel, resulting in highly energy-saving and efficient operation depending on the outside temperature and humidity conditions. I can make you do it.

(Example) Next, an example of the present invention will be described in detail with reference to FIGS. 1 and 2.

FIG. 3 shows a diagram of an air conditioning system according to the present invention, which includes a first cold water production circuit including a refrigerator TA101 and a cooling tower I02, and a two-system cold water production circuit including only a cooling tower 202. The first system shows the cold water production circuit in summer, the cold water side circuit of the refrigerator +01 and the cold water pump 111, and the cooling tower 10.
2 and a cooling water side circuit of a cooling water pump 121 to produce cold water and store it in a buffer tank 400. The second system is a cold water production circuit in winter, and includes a cold water pump 211, a cooling tower 202, and a cold water pump 221, and produces cold water, which is stored in a buffer tank 400.

The cold water produced by these cold water production circuits is stored in a large-capacity buffer tank 400 having a dedicated cold water pit (return) 401 and a cold water pit (feed) 402, and circulates through two cold water side circuits.

In addition, the pumps 111, 121, 221 and 211 serve as switching devices for switching cold water, and when operating in the first system, pumps 11L, ]21 are operated, and pumps 21+ and 2 are operated.
21 is stopped. When operating the second system, the conditions are reversed. The air conditioning cold water circuit then exits the water supply pit 402 of the buffer tank 400, connects to the cold water pump 311, and connects the air conditioner 3C.
It passes through I+ and returns to the cold water pit 401, where it circulates between the two.

Symbols T, T2T, and T4 are temperature sensors, and W B indicates the outside air wet bulb temperature.

Based on this configuration, in the middle period from summer to winter, the computer built in the computer board 501 takes in the outside air temperature T4 and the chilled water pit (return) temperature to determine the production of chilled water by the cooling tower. The second example is shown in FIG.

That is, the outside air wet bulb temperature T4 is taken in (Fl) and its moving average value for 30 minutes is calculated (F2). By using the amount of change as a moving average value that takes time into account, it becomes possible to predict changes in the outside air and fluctuations in the chilled water load.

At the same time, take in the cold water temperature T (F3), calculate its 30-minute moving average value, and predict the fluctuation trend (F4). This 3
The value of 0 minutes is determined from experimental values based on the volume of the air conditioned room, heat load, etc.

Next, the average value of the outside air wet bulb temperature is 7°C or lower than 7°C (F'5), and the average value of the cold water temperature is 10°C to 1
It is within the range of 2°C (F6), and the cold water temperature is decreasing (
In the case of F7), it is possible to use cold outside air, so the refrigerator is stopped and operation is switched to the cooling tower method (F7).
8) (F9).

Also, if the average wet bulb temperature of the outside air mentioned above is higher than 7°C and the average value of the chilled water temperature, which is the calculated value of (F4), is on the rise, stop cooling tower operation and turn off the chiller. Switch to operation (Fil) (F12).

Moreover, if the average value of the cold water temperature or a downward trend is found in (FIO), the operating state up to that point is maintained.

Similarly, in (F7), if the average value of the chilled water temperature is on the rise, the operating state up to that point is maintained.

These automatic operations are performed by a control panel with a built-in sequencer and the like.

In addition, in the second chilled water production circuit, in order to prevent the chilled water temperature from dropping too low in winter, the T3 chilled water temperature is detected, and the rotation speed of the cooling tower fan is controlled and adjusted by the rotation speed control panel 502 so that the temperature reaches the target temperature. .

In this cold water production circuit, the cooling tower is operated with priority over the refrigerator, and the next operation is possible.

(1) Parallel operation In order to reduce the load on the chiller during the intermediate period, the chiller and cooling tower will be operated in parallel.

The refrigerator load is halved, resulting in energy-saving operation.

(2) Single operation Independent operation of only the refrigerator or cooling tower.

(3) Unmanned operation By making the second chilled water production circuit a dedicated cooling tower,
Complex valve operations (or rather, by incorporating a simple start/stop circuit, unmanned operation becomes possible, which saves labor.

(Effects of the Invention) As detailed above, according to the present invention, under the condition that the cooling tower is preferentially restricted based on the determination result of the outside air wet bulb temperature,
Since the cooling tower and the refrigerator can be operated individually or in parallel, it is possible to operate the cooling tower and the refrigerator with a high energy saving effect according to the outside air conditions.

In addition, the chilled water produced in the chilled water production circuit is sent directly to the air conditioner (a buffer tank is installed in the middle, so even if there are short-term fluctuations in the outside temperature, stable air conditioning is achieved without being affected by it. It is possible to make it happen.

[Brief explanation of the drawing]

Figure 1 is a system diagram of an air conditioner according to the present invention, Figure 2 is a system diagram of an air conditioner according to the present invention;
The figure shows a control flowchart thereof, and FIGS. 3 and 4 show system diagrams of a conventional air conditioner. 101... Refrigerator] 02... Cooling tower 111.121, 211.221... Pump 301.
... Air conditioner 400 ... Buffer tank 501 ... Control panel ff12 Figure 3 Figure wS4

Claims (2)

[Claims] (1) In an air conditioner equipped with two chilled water production circuits, the chilled water side circuit of the first system chiller, the second system chilled water side circuit using only the cooling tower using outside air, and A buffer tank that stores the cold water produced in the cold water production circuit and a switching device that switches the connection between the buffer tank and the two cold water side circuits are provided, and the cold water in the buffer tank is transferred to the cold water of the air conditioner. An air conditioner having a cold water production circuit characterized by performing air conditioning by circulating it through a coil. (2) The switching device detects the cold water temperature of the buffer tank and the outside air wet bulb temperature, and allows the cooling tower to operate preferentially to the refrigerator, and changes the operating mode as the outside air bulb temperature becomes lower (i) (ii) As a second step, the first system and the second system are operated in parallel with the cold water circuit using a cooling tower using outside air. ( iii) The chilled water production circuit according to claim (1), characterized by a three-stage switching system in which operation is performed only on the chilled water side circuit using the cooling tower as the third stage, and the operating power of the refrigerator is minimized by sequentially switching. Air conditioner with.