JPH0517533Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an air conditioning system comprising a center unit, terminal air conditioning units, and a refrigeration device to which brine circuits are interconnected.

(Conventional technology) In supermarkets with large store areas, large central heat pump units are installed in separate rooms.
Brine is supplied from here to the heat pump for air conditioning in the store, and hot and cold air is sent out from the outlets of each ceiling indoor unit. In addition, for the case for freezing and refrigeration in a store, for example, brine is supplied from a brine circuit with a cooling tower interposed to each terminal heat pump for refrigeration and freezing, and the terminal heat pump is operated for cooling using the brine as a heat source. , or the defrosting operation is performed as appropriate.

(Problem that the invention aims to solve) However, with the above-mentioned center heat pump unit, when the load on the terminal heat pump for in-store air conditioning becomes large, such as during the summer, the brine temperature may exceed the set upper limit. There was a problem that it could not be carried out satisfactorily. In addition, in order to cope with this problem, it was necessary to increase the equipment for the center heat pump unit.

The object of the present invention is to provide an air conditioning system in which when the temperature of the brine in a center heat pump unit rises, the heat of the brine is used as a heat source for defrosting the refrigerator, thereby suppressing the rise in the temperature of the brine. Our goal is to provide the following.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a center heat pump unit that adjusts the temperature of the first brine and circulates it through the first brine circuit;
In an air conditioning system comprising a terminal air conditioning unit that is connected for heat exchange to a second brine circuit and performs air conditioning, and a heat pump type refrigerator that is connected for heat exchange to a second brine circuit that has a cooling tower interposed therebetween and performs cooling. , the first brine circuit and the second brine circuit are connected for heat exchange by a brine heat exchanger, and the second brine circuit is connected in parallel with the brine heat exchanger via a first three-way valve. A branched first branch circuit and a second branch circuit connected in parallel to the cooling tower via a second three-way valve.
a second branch circuit in which a brine circuit is branched, and the first three-way valve is switched to the first branch circuit side, and the second three-way valve is switched to the cooling tower side to cool the refrigeration device. operation, and when the temperature of the first brine exceeds a set upper limit value, the first three-way valve is switched to the brine heat exchanger side, and the second three-way valve is switched to the second branch circuit side. It is equipped with a control device that switches the refrigeration system to defrost operation.

(Function) According to the present invention, when the first brine is at a normal temperature, the first three-way valve is switched to the first branch circuit side, and the second three-way valve is switched to the cooling tower side. , the first by brine heat exchanger
There is no heat exchange between the second brine circuit and the second brine circuit. In this state, the refrigeration system becomes unrelated to the center heat pump unit and performs cooling operation by discharging heat from the cooling tower. When the temperature of the first brine exceeds the upper limit, the temperature of the first brine exceeds the upper limit.
the three-way valve is switched to the brine heat exchanger side, the second forward valve is switched to the second branch circuit side,
Heat exchange using a cooling tower is eliminated and heat exchange is performed using a brine heat exchanger. In this state, the refrigeration device is operated for defrosting, and the heat source for the defrosting is supplied from the first brine through the brine heat exchanger.

(Embodiment) FIG. 1 is a block diagram of an air conditioning system showing a first embodiment of the present invention.

In the figure, 1 is a center heat pump unit (hereinafter referred to as the center unit), 2 is a first brine circuit connected to the center unit 1, and 3 is a center heat pump unit.
1 is a circulation pump that circulates the first brine through the brine circuit 2, 4 is a temperature detector that detects the temperature of the brine, and 5A and 5B are refrigerant circuits connected to the brine circuit 2 for heat exchange and air condition the store. This is a heat pump type terminal air conditioning unit. 6 is a second brine circuit, 7 is a circulation pump that circulates the second brine through the brine circuit 6, 8 is a cooling tower interposed in the brine circuit 6, 9A, 9B
1 is a heat pump type refrigeration device in which a refrigerant circuit is connected to a brine circuit 6 for heat exchange to cool the inside of a show case in the store, and 10 is a central control device configured with a microcomputer to control this air conditioning system.

Reference numeral 11 designates a double-tube brine heat exchanger, in which one tube 11a is interposed in the brine circuit 2, and the other tube 11b is interposed in the brine circuit 6. Heat exchange between the brines takes place.

12 is a first branch circuit; 13 is a first three-way valve; the first branch circuit 12 branches from the brine circuit 6 via the first three-way valve 13 and is connected in parallel with the brine heat exchanger 11 It forms a branch road. 14
is the second branch circuit, 15 is the second three-way valve, and
The branch circuit 14 branches from the brine circuit 6 via a second three-way valve to form a branch path parallel to the cooling tower 8.

16A and 16B are double-tube brine-refrigerant heat exchangers, which connect the brine circuit 6 and refrigerators 9A and 9B.
heat exchange between each refrigerant circuit. 17A,1
7B is a compressor, 18A, 18B are four-way valves,
19A and 19B are expansion valves, and 20A and 20B are air heat exchangers that send cold air or warm air for defrosting to the show case.

The central control device 10 includes terminal air conditioning units 5A,
5B, and also controls the switching of each three-way valve 13, 15 and the refrigerating device 9 based on the temperature detected by the temperature detector 4 through program control to be described later.
A and 9B are switched between cooling operation and defrosting operation.

Next, the control operation of the air conditioning system shown in FIG. 1 by the central control device 10 will be explained. FIG. 2 is a flowchart showing the control operation.

First, the center unit 1 and circulation pumps 3, 7 are operated (S1), and then the terminal air conditioning units 5A,
5B is operated (S2), and initially, refrigeration equipment 9A, 9
The flag indicating the operating state of B is 0, that is, the cooling operation is set (S3). The first three-way valve 13 is switched to the first branch circuit 12 side (S4), and the second three-way valve 1
5 is switched to the cooling tower 8 side (S5),
The refrigerators 9A and 9B are operated for cooling (S6). In the refrigerators 9A and 9B, the refrigerant circulates in the direction shown by the solid arrow and passes through the air heat exchangers 20A and 20.
Cold air is sent out from B to cool the inside of the show case. The heat of the pressurized and heated refrigerant is then exchanged by the brine-refrigerant heat exchangers 16A and 16B, transferred to the brine of the second brine circuit 6, and released from the cooling tower 8 to the outside. The central control device 10 sets a first set temperature Ts1 and a second set temperature Ts2 slightly higher than the upper limit of the detected temperature TW of the temperature detector 4, so that the detected temperature TW is higher than the first set temperature Ts1. When the temperature is lower than the set temperature Ts1 (S7), the cooling operation according to each step S3 to S7 is continued.

Due to excessive loads on the terminal air conditioning units 5A and 5B during the summer, the detected temperature TW may be lower than the first set temperature.
Ts1 is exceeded (S7), at this time more than a predetermined time has passed since the previous defrost and defrosting is required (S8), and when the detected temperature TW becomes higher than the second set temperature Ts2 (S9), a flag is flagged. is 1, that is, the defrosting operation is started (S10). As a result, the first three-way valve 13 is switched to the brine heat exchanger 11 side (S11),
Then, the second three-way valve 15 is switched to the second branch circuit 14 side (S12), and the refrigerators 9A and 9B are operated for defrosting (S13). Note that if the predetermined time has not passed since the previous defrosting (S8), the cooling operation is continued (S3 to S8). In the refrigerators 9A and 9B, the refrigerant circulates in the direction indicated by the dashed arrow,
Warm air is sent out from the air heat exchangers 20A and 20B to defrost the air. The brine in the second brine circuit 6 circulates through the brine heat exchanger 11 without passing through the cooling tower 8, and the brine-refrigerant heat is released from the air heat exchangers 20A and 20B. Through the exchangers 16A, 16B the temperature of the brine is reduced, resulting in heat transfer from the first brine circuit 2 to the second brine circuit 6 through the brine heat exchanger 11. Therefore, the detected temperature TW of the first brine circuit 1 decreases. The central control device 10 sets an upper limit value for the defrosting time, and during the defrosting time (S14), when the detected temperature TW is higher than the set temperature Ts1 (S15) and further higher than the set temperature Ts2 ( S9) or detected temperature
If TW is within the range of each set temperature Ts1 and Ts2 (S15, S9) and the flag is 1, the operations of these steps S9 to S15 or S9, S16, and S11 to S15 are repeated to defrost. Operation continues. Then, the defrosting time has passed (S14), or the detected temperature TW has reached the set temperature Ts1.
When the temperature becomes below, the process returns to step S3, and the refrigerators 9A and 9B return to cooling operation. In addition, during cooling operation (flag is 0), if the detected temperature TW is within the range of each set temperature Ts1 and Ts2, (S7,
S8, S9, S16), the cooling operation continues (S4~
S9, S16).

FIG. 3 is a configuration diagram of an air conditioning system showing a second embodiment of the present invention. In this figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and the different parts will be explained below.

21 is a second brine circuit, and 22A and 22B are refrigerators in which refrigerant circuits are connected to the brine circuit 21 for heat exchange. The refrigeration devices 22A, 22B are connected for heat exchange with the brine circuit 21 by one of the brine-refrigerant heat exchangers 23A, 23B to constitute a heat pump similar to that shown in FIG. heat exchanger 2
On-off valves 25A and 2 are connected to the series circuit with 0A and 20B.
The series circuit of the expansion valves 26A, 26B and the other brine-refrigerant heat exchanger 27A, 27B is connected in parallel via the brine-refrigerant heat exchanger 27
A and 27B are also connected to the brine circuit 21 for heat exchange.

The air conditioning system of FIG. 3 is similarly controlled according to the flowchart of FIG. That step S6
During the cooling operation, the on-off valves 25A and 25B are closed, and the refrigerant circulates as shown by the solid arrow to cool the show case. At this time, heat is released from the cooling tower 8 to the outside. step
During defrosting operation using S13, open/close valves 25A, 25
B is opened, and the refrigerant flows through the air heat exchangers 20A and 20B and the brine as shown by the solid line arrow and the broken line arrow.
The flow is divided into refrigerant heat exchangers 27A and 27B. The temperature of the brine-refrigerant heat exchangers 27A, 27B decreases, heat is recovered from the brine circuit 21 to the refrigerant circuit, and the capacity of the air heat exchangers 20A, 20B is lower than during normal cooling operation. This defrosts the air heat exchangers 20A and 20B. At this time, heat is transferred from the brine circuit 2 to the brine circuit 21 through the brine heat exchanger 11, and the detected temperature TW
decreases.

FIG. 4 is a configuration diagram of an air conditioning system showing a third embodiment of the present invention. In this figure, the same parts as in FIG. 1 are designated by the same reference numerals, and the different parts will be explained below.

28 is a second brine circuit, and 29A and 29B are refrigerators in which refrigerant circuits are connected to the brine circuit 28 for heat exchange. The refrigerators 29A and 29B are the first
Instead of the air heat exchangers 20A and 20B shown in the figure, a set of refrigerant-based air heat exchangers 30A and 30B and brine-based air heat exchangers 31A and 31B is provided, and the brine circuit 28 is The brine is distributed from the air to the air heat exchangers 31A, 31B, and the flowing air is directed to the air heat exchangers 30A, 30B via the air heat exchangers 31A, 31B.

Figure 5 shows air heat exchangers 30A and 31 in Figure 4.
It is a schematic diagram showing the arrangement of A, or 30B and 31B. The refrigerant heat exchanger 30A or 30B and the brine heat exchanger 31A or 31B are installed vertically in the air passage on the back side of the show case 33, and a fan 34 is installed above them. The circulating air passes through heat exchanger 3 as shown by the arrow.
He is trying to flow from 1A or 31B toward heat exchanger 30A or 30B and to be sent to warehouse interior 35.

The air conditioning system of FIG. 4 is similarly controlled according to the flowchart of FIG. That step S6
During the cooling operation, the on-off valves 32A and 32B are closed, and the refrigerant circulates as shown by the solid arrow to cool the show case. At this time, heat is released from the cooling tower 8 to the outside. step
During defrosting operation using S13, on-off valves 32A, 32
B is opened and brine flows to the air heat exchangers 31A and 31B as shown by the dashed arrows. Therefore, the brine in the brine circuit 28 is cooled by the air inside the refrigerator, and the temperature of the air that has passed through the air heat exchangers 31A and 31B is higher than during normal cooling operation. As a result, the air heat exchangers 30A and 30B are defrosted. At this time, heat is transferred from the brine circuit 2 to the brine circuit 28 through the brine heat exchanger 11, and the detected temperature TW decreases.

(Effect of the invention) As explained above, according to the invention, the temperature of the first pump is adjusted by the center heat pump unit.
The brine circuit and the second brine circuit for the heat source of the refrigeration system are connected for heat exchange by a brine heat exchanger, and when the temperature of the first brine circuit rises above the set temperature, the refrigeration system is turned off. Since the defrosting operation is performed and the heat source is supplied from the first brine circuit, when the load at the terminal of the center heat pump unit temporarily increases, it is possible to cope with the overload. Therefore, an economical air conditioning system can be realized without the need for excessive center heat pump units.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an air conditioning system showing a first embodiment of the present invention, Fig. 2 is a flowchart showing the operation of the air conditioning system, and Fig. 3 is a diagram of an air conditioning system showing a second embodiment of the invention. FIG. 4 is a configuration diagram of an air conditioning system showing a third embodiment of the present invention, and FIG. 5 is a diagram showing the arrangement of the air heat exchanger shown in FIG. 4. 1... Center heat pump unit, 2... First brine circuit, 4... Temperature detector, 5A, 5
B... Terminal air conditioning unit, 6, 21, 28... Second brine circuit, 8... Cooling tower, 9
A, 9B, 22A, 22B, 29A, 29B...
Refrigeration device, 10... central control device, 11... brine heat exchanger, 12... first branch circuit, 13...
...First three-way valve, 14...Second branch circuit, 15
...Second three-way valve, 16A, 16B, 23A, 2
3B, 27A, 27B...Brine-refrigerant heat exchanger.

Claims (1)

[Claims for Utility Model Registration] A center heat pump unit that adjusts the temperature of the first brine and circulates it through the first brine circuit, and a terminal air conditioning unit that is connected to the first brine circuit for heat exchange and performs air conditioning. , an air conditioning system equipped with a heat pump type refrigeration device that is connected for heat exchange to a second brine circuit with a cooling tower interposed therebetween and performs cooling, wherein the first brine circuit and the second brine circuit are connected to brine heat a first brine circuit connected for heat exchange by an exchanger and branching the second brine circuit in parallel with the brine heat exchanger via a first three-way valve;
and a second branch circuit in which the second brine circuit is branched in parallel with the cooling tower via a second three-way valve, and the first three-way valve is connected to the first branch circuit. At the same time, the second three-way valve is switched to the cooling tower side to operate the refrigerator for cooling, and when the temperature of the first brine exceeds a set upper limit, the first three-way valve is switched to the cooling tower side. An air conditioning system comprising: a control device that switches the second three-way valve to the exchanger side and switches the second three-way valve to the second branch circuit side to operate the refrigeration device in defrosting mode.