JPH0131898Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention is a heat recovery refrigeration system, specifically a heat recovery refrigeration system that is mainly equipped with a turbo compressor and that enables dedicated cooling operation and heat recovery operation. Regarding equipment.

(Prior Art) This type of refrigeration device is already known as described in Japanese Utility Model Application No. 56-96262 and shown in FIG. 3.

The system shown in Fig. 3 takes into consideration the fact that the condensing pressure in heat recovery operation generally needs to be much higher than that in cooling-only operation, so each condensing pressure exerts its optimum capacity. Two turbo compressors, that is, a first compressor 50 for cooling-only operation
and a second compressor 51 for heat recovery operation, and the discharge sides of these first and second compressors 50, 51 are connected to one condenser 54 having a heat exchange pipe 52 for heat recovery and a heat radiation pipe 53. while connected to each of the compressors 50, 5
1 is connected to an evaporator 55 having a cooling heat exchange tube (not shown), and further, the condenser 54 and the evaporator 55 are connected via an expansion mechanism 56, and thus, During cooling-only operation, only the first compressor 50 is driven to handle the cooling load, while
During the heat recovery operation, only the second compressor 51 is driven to handle the heating load and the cooling load. In addition, in Fig. 3, 57 and 58 are check valves, and solid line arrows and broken line arrows are the first and second check valves, respectively.
Each refrigerant cycle formed by driving compressors 50 and 51 is shown.

However, with such a configuration, heating load and cooling load are handled by one second compressor 5 during heat recovery operation.
Since I was trying to process it in step 1, I did the following 2.
Two problems had arisen.

If the maximum cooling load during heat recovery operation is larger than the maximum heating load, the capacity of the second compressor 51 must be increased to match the maximum cooling load, and if the second compressor 51 has a large There was a problem that was shaping up.

In addition, it is generally known that the power required for the compressor increases as the condensing pressure increases even when processing the same size of cooling load. If the heating load exceeds the heating load, the cooling load that exceeds the heating load (hereinafter referred to as excess cooling load) must also be handled by the second compressor 51, and one condenser Since only 54 was used, the condensing (discharge) pressure would increase, resulting in an increase in the power required to handle the excess cooling load, which led to a problem that the energy efficiency would deteriorate accordingly. be.

(Purpose of the invention) The purpose of the invention is to provide a compressor for heat recovery and a compressor dedicated to cooling, as in the past, but to provide separate condensers for each of these compressors to recover heat. During operation, the cooling load is handled by the heat recovery compressor, and if the cooling load increases and cannot be handled by the heat recovery compressor, this excess cooling load is handled by the cooling dedicated compressor. A compressor and a condenser corresponding to the compressor can be operated to perform processing, thereby reducing the capacity of the compressor for heat recovery and downsizing. The point is that the power can be reduced compared to conventional methods.

(Structure of the invention) The structure of the invention includes a first compressor for cooling only and a second compressor for heat recovery, and a first condenser for cooling only and a second compressor for heat recovery on the discharge side of these compressors. the second of
The condensers are connected to each other, and the evaporator connected to the outlet side of each of these condensers is connected to the suction side.
While enabling dedicated cooling operation and heat recovery operation,
A control mechanism is provided to detect a cooling load during a heat recovery operation and drive control of the first compressor, and the control mechanism detects a cooling load during a heat recovery operation,
It is detected that the cooling capacity exerted by the operation of the second compressor is insufficient, and in this case, in addition to the second compressor, the first compressor is also driven; The discharge gas of the first compressor is condensed in the first condenser provided separately from the second condenser for heat recovery, and the condensation pressure of this discharge gas is set to the condensation pressure of the discharge gas of the second compressor. This allows it to be set lower.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

What is shown in FIG. 1 is a heat recovery type refrigeration system that uses two turbo compressors and enables dedicated cooling operation and heat recovery operation.

In Figure 1, 1 is the first compressor dedicated to cooling, which has a blower that provides the best efficiency in the adiabatic head during cooling operation, and 2, the heat recovery compressor that has the blower that provides the best efficiency in the adiabatic head during heat recovery operation. The first and second compressors 1 and 2 are respectively provided with driving motors M ₁ and M ₂ . The suction sides of the first and second compressors 1 and 2 are both connected to the evaporator 3, while the discharge side of the first compressor 1 is connected to the first condenser 4 dedicated to cooling. The discharge side of the second compressor 2 is connected to a second condenser 5 for heat recovery, and the outlet sides of the first and second condensers 4 and 5 are connected to the evaporator 3 through an expansion mechanism 6. It connects to.

Further, the first condenser 4 is provided with a heat radiation pipe 7 through which cooling water flows, the evaporator 3 is provided with a first heat exchange pipe 8 that connects to a cooling load, and the second condenser 5 is provided with a first heat exchange pipe 8 that is connected to a cooling load. A second heat exchange pipe 9 connected to the heating load is installed inside each of them.

In this way, by driving the first compressor 1, the refrigerant is transferred from the first compressor 1 to the first condenser 4 to the expansion mechanism 6.
A first refrigerant cycle can be formed in which the evaporator 3 is circulated from the evaporator 3 to the first compressor 1, and the evaporator 3 processes the cooling load. →Second condenser 5→Expansion mechanism 6→
A second refrigerant cycle can be formed in which the second condenser 5 handles the heating load and the evaporator 3 handles the cooling load by circulating the refrigerant from the evaporator 3 to the second compressor 2. By driving the machines 1 and 2 together, the first and second refrigerant cycles can be operated simultaneously.

Further, on the suction sides of the first and second compressors 1 and 2, there are suction vanes 10 having valve opening adjustment motors M ₃ and M ₄ for capacity control, respectively.
11 are provided. A first temperature detector 12 detects the cold water temperature on the outlet side of the first heat exchange tube 8 in the evaporator 3, and a controller outputs the output to the motor _M3 based on the output of the detector 12.
TC ₁ is provided, and the capacity of the first compressor 1 can be controlled by the operation of the controller TC ₁ . Note that the controller TC ₁ outputs an output based on the temperature difference between the detected cold water temperature and the set cold water temperature. Further, the second condenser 5
a second temperature detector 13 for detecting the hot water temperature on the outlet side of the second heat exchange tube 9; and a controller _TC2 for outputting the output to the motor _M4 based on the output of the detector 13. The capacity of the second compressor 2 can be controlled by operating the TC ₂ .

Note that the controller TC ₂ also outputs an output based on the temperature difference between the detected hot water temperature and the set hot water temperature.

In addition, in FIG. 1, 14 is an auxiliary expansion mechanism, 15 is a cooling tower, P ₁ to P ₃ are pumps, 40, 4
1 is a check valve.

Next, the operation control circuit of the above-mentioned refrigeration system will be explained based on FIG.

This control circuit is connected between the power lines to a changeover switch SW that switches between cooling-only operation and heat recovery operation, an auxiliary cooling relay SX connected to the cooling side contact S of the switch SW, and a heat recovery side contact W. Heat recovery auxiliary relay WX
a changeover switch circuit 16 consisting of a first compressor 1 for controlling the drive of the motor _M1 of the first compressor
A first compressor drive control circuit 17 consisting of a series circuit of the switch _MC1 and the normally open contact SX-1 of the auxiliary relay SX for cooling, and a second compressor drive control circuit 17 for controlling the drive of the motor _M2 of the second compressor 2.
a second compressor drive control circuit 18 consisting of a series circuit of a switch MC ₂ and a normally open contact WX-1 of the auxiliary relay WX for heat recovery; a capacity of each of the first and second compressors 1 and 2; The controllers TC ₁ and TC ₂ for controlling the suction vane valve opening adjustment circuit 19 having the motors M ₃ and M ₄ of the vanes 10 and 11 are connected, and a cooling load determination device to be described later is connected. 20
A cooling load determination circuit 21 is provided which connects the normally open contact WX-1 of the auxiliary relay WX for heat recovery and the first switch _MC1 in series.

The cooling load determiner 20 detects the cooling load and closes when the load becomes larger than a set value,
The opening/closing control of the determiner 20 is performed by, for example, detecting the cold water inlet temperature of the first heat exchange tube 8, comparing it with the set value, and outputting an output. The output contact may also be used. Alternatively, the calculation may be performed using an arithmetic unit based on the cold water inlet/outlet water temperature difference and the amount of water, and the output thereof.

Thus, the cooling load determination circuit 21 constitutes a control mechanism that detects the cooling load and controls the drive of the first compressor 1 dedicated to cooling during the heat recovery operation.

Note that T is a timer, and T-1 is a normally open contact for time-limited operation of the timer T, which is used to prevent the first compressor 1 from being driven for a predetermined period of time when the heat recovery operation is started.

Next, the operation of the refrigeration system configured as described above will be explained separately.

Heat recovery operation When the changeover switch SW is switched to the heat recovery side,
The auxiliary relay WX is energized and its normally open contacts
When WX-1 is closed, the second switch _MC2 is energized and the second compressor 2 is driven, and the timer T is also energized and started, and after a predetermined time, the normally open contact T-1 is closed. to be accomplished.

In this way, by driving the second compressor 2,
The second refrigerant cycle (dashed line arrow in FIG. 1) acts to cool the second heat exchange tube 9 in the second condenser 5
This makes it possible to perform a heat recovery operation in which a heating operation for heating the water flowing through the first heat exchange tube 8 and a cooling operation for cooling the water flowing through the first heat exchange tube 8 using the evaporator 3 are performed simultaneously. At this time, the controller TC ₂ acts, and the second temperature detector 13
Based on the hot water temperature detected by the second compressor 2.
Capacity control is performed.

At this time, if the cooling load detected by the cooling load determiner 20 is less than or equal to the set value of the determiner 20, in other words, the heating load is balanced with the cooling load, and the second When the compressor 2 can be driven to handle the heating load and the cooling load at the same time, the determination device 20 is opened, and therefore the first switch MC ₁ is de-energized and the first
Compressor 1 is maintained in a stopped state.

On the other hand, the cooling load detected by the cooling load determination device 20 exceeds the set value of the determination device 20, in other words, the cooling load becomes larger than the heating load, and the cooling load is If the operation based on the heating load of the compressor 2 is no longer able to handle the heating load, the determination device 20 closes and the first compressor 1 is also driven, and the first refrigerant cycle is activated together with the second refrigerant cycle. (solid line arrow in Figure 1) can be used to increase the cooling capacity of this refrigeration system.

At this time, since the discharge gas of the first compressor 1 is condensed in the first condenser 4 provided separately from the second condenser 5 as described above, the condensation pressure of the first refrigerant cycle is can be set to a value as low as necessary for cooling operation, regardless of that of the second refrigerant circuit.

The cooling-only operation is performed by driving the first compressor 1 and stopping the second compressor 2, which is the same as in the conventional case, and therefore a description thereof will be omitted.

(Effect of the invention) As described above, according to the invention, during heat recovery operation,
Due to the control mechanism, in the operation of the second compressor 2,
The first compressor 1 can be driven when the cooling load cannot be handled, and the condensation pressure of the discharge gas of the first compressor 1 is different from the condensation pressure of the discharge gas of the second compressor 2. It can be set to different low values, and thus the following effects can be obtained.

The capacity of the second compressor 2 for heat recovery needs to be a capacity that can handle only the maximum heating load, so no matter how much larger the maximum cooling load during heat recovery operation is than the maximum heating, the second Compressor 2
Capacity can be reduced, making it possible to downsize. Also,
Furthermore, during heat recovery operation, the cooling load cannot be handled by driving the second compressor 2, and the first compressor 1
If the first compressor 1 is also driven, the condensation pressure of the discharged gas from the first compressor 1 is used as the second compressor for heat recovery, as described above.
Since the condensing pressure can be lower than the condensing pressure of the compressor 2, the required power can be reduced compared to the conventional one, and therefore energy efficiency can be improved.

[Brief explanation of the drawing]

Fig. 1 is a refrigerant circuit diagram of an embodiment of the present invention;
The figure is a control circuit diagram of the same embodiment, and FIG. 3 is a refrigerant circuit diagram showing a conventional example. 1...First compressor, 2...Second compressor, 3...
...Evaporator, 4...First condenser, 5...Second condenser, 20...Cooling load determination device, 21...Cooling load determination circuit, control mechanism.

Claims (1)

[Scope of utility model registration request] It is equipped with a first compressor 1 dedicated to cooling and a second compressor 2 for heat recovery, and on the discharge side of these compressors 1 and 2,
A first condenser 4 dedicated to cooling and a second condenser 5 for heat recovery are connected to each other, and an evaporator 3 connected to the outlet side of each of these condensers 4 and 5 is connected to the suction side. A heat recovery type refrigeration system that enables dedicated operation and heat recovery operation, and is further equipped with a control mechanism that detects the cooling load during the heat recovery operation and controls the drive of the first compressor 1.