WO2023068197A1 - Freezing apparatus - Google Patents

Abstract

A freezing apparatus comprising: a main circuit through which a refrigerant flows; a plurality of compressors; a non-return valve; a condenser; a receiver; a first expansion valve; an evaporator; an injection flowpath; an electromagnetic valve disposed upon the injection flowpath; a fluid level detection unit that detects the amount of refrigerant stored inside the receiver; and a control unit. The control unit closes the first expansion valve prior to stopping the compressors and closes the electromagnetic valve at the point that the fluid level detection unit has detected that the amount of fluid component inside the receiver has reached a predetermined upper value.

Description

refrigeration equipment

The present disclosure relates to refrigeration equipment.
This application claims priority to Japanese Patent Application No. 2021-170169 filed in Japan on October 18, 2021, the contents of which are incorporated herein.

A typical refrigeration system includes a compressor, a condenser, an expansion valve, a receiver (gas-liquid separator), and an evaporator. The high temperature, high pressure gaseous refrigerant produced by the compressor is first sent to the condenser. In the condenser, heat is exchanged between refrigerant and air, and the refrigerant becomes a high-temperature, high-pressure liquid refrigerant. After that, by passing through the expansion valve, the temperature and pressure of the refrigerant decrease, and the refrigerant becomes a low-temperature, low-pressure liquid refrigerant. Further, by exchanging heat with air in the evaporator, the refrigerant becomes a low-temperature, low-pressure gaseous refrigerant. In this process, the temperature of the space in which the condenser or evaporator is installed is adjusted. In particular, in recent years, in order to improve the output of a refrigeration system, there are cases in which a plurality of compressors are arranged in series (see Patent Document 1 below). That is, the low-pressure side compressor and the high-pressure side compressor are arranged in series.

JP 2020-204454 A

In the refrigeration system as described above, conventionally, when the operation is stopped, the refrigerant is evenly present on the piping route. Therefore, it is necessary to secure a certain level or more of pressure resistance performance of piping and various devices. As a result, the pressure resistance performance of the compressor on the low pressure side, in particular, needs to be the same as the pressure resistance performance of the compressor on the high pressure side, which causes an increase in cost.

The present disclosure has been made to solve the above problems, and aims to provide a refrigeration system that can be manufactured at a lower cost.

In order to solve the above problems, a refrigeration system according to the present disclosure includes a main circuit as a circulation flow path through which refrigerant flows, a plurality of compressors arranged in series on the main circuit, and the plurality of compressors a check valve arranged between, a condenser arranged downstream of the plurality of compressors, a receiver arranged downstream of the condenser, and a first arranged downstream of the receiver an expansion valve, an evaporator arranged downstream of the expansion valve, an injection flow path connecting the receiver and an upstream side of the check valve between the plurality of compressors, a solenoid valve arranged on the injection flow path; a liquid level detection unit that detects the amount of the liquid component of the refrigerant stored in the receiver; and a control unit, wherein the control unit controls the compressor. The first expansion valve is closed before stopping, and the electromagnetic valve is closed when the liquid level detection unit detects that the amount of the liquid component in the receiver has reached a predetermined upper limit. do.

According to the present disclosure, it is possible to provide a refrigeration system that can be manufactured at a lower cost.

1 is a circuit diagram showing the configuration of a refrigeration system according to a first embodiment of the present disclosure; FIG. FIG. 2 is a circuit diagram showing the configuration of the refrigerating apparatus according to the first embodiment of the present disclosure, showing a state before operation is stopped; FIG. FIG. 2 is a circuit diagram showing the configuration of the refrigerating apparatus according to the first embodiment of the present disclosure, showing a state after operation is stopped; FIG. FIG. 10 is a circuit diagram showing the configuration of a refrigeration system according to a second embodiment of the present disclosure, showing a state before operation is stopped; [ Fig. 10] Fig. 10 is a circuit diagram showing the configuration of the refrigeration apparatus according to the second embodiment of the present disclosure, showing a state after operation is stopped. FIG. 10 is a circuit diagram showing the configuration of the refrigeration system according to the second embodiment of the present disclosure, and shows a state in which the refrigerant in the receiver is being transferred to another receiver while the system is stopped.

[First embodiment]
(Composition of refrigeration equipment)
A refrigerating apparatus 100 according to a first embodiment of the present disclosure will be described below with reference to FIGS. 1 to 3. FIG. This refrigerating device 100 is a heat pump device that performs heat exchange between a refrigerant and air by operating in a refrigerating cycle.

As shown in FIG. 1, the refrigeration system 100 includes a main circuit 90 formed as a circulation flow path, a first compressor 1 (compressor), a second compressor 2 (compressor), and a condenser 4. , the first expansion valve 7, the receiver 6, the liquid level detector 61, the pressure detector 62, the second expansion valve 5, the evaporator 8, the injection passage 11, the solenoid valve 13, and the accumulator 15 , a check valve 18 , and a control section 80 .

(Configuration of first compressor and second compressor)
The main circuit 90 is filled with refrigerant in a liquid or gaseous state. The first compressor 1 and the second compressor 2 are arranged in series on the main circuit 90 . That is, the discharge side of the first compressor 1 faces the suction side of the second compressor 2 . As the first compressor 1 and the second compressor 2, for example, a scroll compressor, a rotary compressor, or a scroll compressor can be used. In the following description, on the main circuit 90, the side where the second compressor 2 is located when viewed from the first compressor 1 is sometimes called the downstream side, and the opposite side is sometimes called the upstream side. A check valve 18 is provided between the first compressor 1 and the second compressor 2 . The check valve 18 is configured to allow the refrigerant to flow only in the direction from the upstream side to the downstream side.

(Configuration of condenser)
A condenser 4 is arranged downstream of the second compressor 2 . The condenser 4 is a heat exchanger for exchanging heat between the outside air and the refrigerant. A fan (not shown) is provided in the vicinity of the condenser 4 to forcefully exchange heat between the air and the refrigerant. The high-temperature, high-pressure gaseous refrigerant generated by the second compressor 2 is condensed by passing through the condenser 4 to become a high-temperature, high-pressure liquid refrigerant.

A second expansion valve 5 is provided downstream of the condenser 4 . The high-temperature and high-pressure liquid refrigerant supplied from the condenser 4 is reduced in pressure and temperature by passing through the second expansion valve 5 and becomes a low-temperature and low-pressure liquid refrigerant.

(Receiver configuration)
A receiver 6 is connected to the downstream side of the second expansion valve 5 . The receiver 6 is a container for storing at least part of the liquid refrigerant that has passed through the second expansion valve 5 . The amount of liquid refrigerant that can exist in the main circuit 90 varies depending on the operating conditions of the refrigeration system 100 . A receiver 6 is provided to accommodate this variation. A liquid level detector 61 and a pressure detector 62 are attached to the receiver 6 . The liquid level detection unit 61 detects the amount of liquid refrigerant in the receiver 6 and transmits it to the control unit 80 as an electric signal. The pressure detection unit 62 detects the pressure inside the receiver 6 and transmits it to the control unit 80 as an electric signal.

A first expansion valve 7 is arranged further downstream of the receiver 6 . The first expansion valve 7 is provided to further reduce the temperature and pressure of the low temperature, low pressure liquid refrigerant that has passed through the receiver 6 . The second expansion valve 5 and the first expansion valve 7 are electromagnetic expansion valves that can be switched between open and closed states by an electric signal from the outside.

(Configuration of evaporator)
An evaporator 8 is provided downstream of the first expansion valve 7 . The evaporator 8 is a heat exchanger for exchanging heat between the outside air and the refrigerant. A fan (not shown) is provided in the vicinity of the evaporator 8 to forcefully exchange heat between the air and the refrigerant. The low-temperature, low-pressure liquid refrigerant that has passed through the first expansion valve 7 evaporates by exchanging heat with the outside air when passing through the evaporator 8 to become a low-temperature, low-pressure gaseous refrigerant.

An accumulator 15 is provided downstream of the evaporator 8 . The accumulator 15 is a container for storing liquid refrigerant that has not been completely evaporated in the evaporator 8 . After the liquid component is removed by the accumulator 15, the gaseous refrigerant is sent to the first compressor 1 again and compressed. The refrigeration system 100 is operated by continuously repeating such a cycle (refrigeration cycle).

(Structure of injection channel)
The injection flow path 11 connects between the above-described check valve 18 and the first compressor 1 (that is, the low-pressure side compressor) and the receiver 6 . A solenoid valve 13 is provided on the injection flow path 11 . The solenoid valve 13 can be switched between open and closed states by an electric signal from the outside.

(Configuration of control unit)
The control unit 80 is provided to switch between the open/closed state of each valve device described above and the operating state of the first compressor 1 and the second compressor 2 by an electric signal. Specifically, the control unit 80 can switch the open/closed states of the first expansion valve 7 , the second expansion valve 5 , and the electromagnetic valve 13 . Further, the control unit 80 can switch between driving and stopping the first compressor 1 and the second compressor 2 .

(Effect)
Next, an example of the operation of the refrigeration system 100 will be described. As shown in FIG. 1 , the controller 80 closes the electromagnetic valve 13 when the refrigerating apparatus 100 is normally operated. As a result, the injection flow path 11 is closed and the refrigerant circulates only through the main circuit 90 . Circulation of the refrigerant in the main circuit 90 causes the above-described refrigeration cycle to occur continuously.

Next, with reference to FIGS. 2 and 3, the operation when stopping the refrigeration system 100 will be described. In the refrigerating apparatus 100 as described above, conventionally, when the operation is stopped, the refrigerant is evenly present in the piping path. Therefore, it is necessary to secure a certain level or more of pressure resistance performance of piping and various devices. As a result, the pressure resistance performance of the first compressor 1 on the low-pressure side in particular needs to be the same as the pressure resistance performance of the second compressor 2 on the high-pressure side, causing an increase in cost.

Therefore, the refrigerating apparatus 100 according to this embodiment is configured to collect the refrigerant into the receiver 6 by performing the operation described below. As shown in FIG. 2, the controller 80 first closes the first expansion valve 7 . Thereby, the downstream side of the receiver 6 in the main circuit 90 is blocked. As a result, the refrigerant in the main circuit 90 and the injection flow path 11 is sequentially stored in the receiver 6 .

After that, as shown in FIG. 3, when the liquid level detection unit 61 detects that the receiver 6 is filled with liquid refrigerant (that the amount of refrigerant has reached the upper limit), the control unit 80 causes the second expansion valve 5, and the solenoid valve 13 is closed. As a result, the receiver 6 is disconnected from the main circuit 90 . Subsequently, the control unit 80 stops driving the first compressor 1 and the second compressor 2 . As described above, the refrigerating apparatus 100 is stopped.

As described above, in the refrigeration system 100 according to the present embodiment, the first compressor 1 and the second compressor 2 are operated with the first expansion valve 7 closed prior to stopping the operation. Thereby, the refrigerant existing in the main circuit 90 and each device can be recovered in the receiver 6 . Therefore, when the operation of the refrigerating device 100 is stopped, the refrigerant is less likely to remain in the main circuit 90 and each device, and particularly the pressure resistance performance of the first compressor 1 on the low pressure side can be lowered. As a result, the manufacturing cost and maintenance cost of the refrigeration apparatus 100 can be reduced.

Further, according to the above configuration, closing the second expansion valve 5 in addition to the electromagnetic valve 13 causes the receiver 6 to be disconnected from the main circuit. Thereby, the refrigerant can be stably sealed in the receiver 6 .

The first embodiment of the present disclosure has been described above. Various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure.

[Second embodiment]
Next, a refrigeration system 200 according to a second embodiment of the present disclosure will be described with reference to FIGS. 4 to 6. FIG. In addition, the same code|symbol is attached|subjected about the structure similar to said 1st embodiment, and detailed description is abbreviate|omitted.

As shown in FIG. 4, this embodiment differs from the first embodiment in the number of compressors. Specifically, on the main circuit 90, in addition to the first compressor 1 on the lowest pressure side, two second compressors 2a and 2b on the high pressure side are provided. One check valve 18 (18a, 18b) is provided upstream of each of the second compressors 2a, 2b.

Furthermore, in this embodiment, a plurality of sets (two sets) each of the receiver 6, the first expansion valve 7, the injection passage 11, and the electromagnetic valve 13 described in the first embodiment are provided. In the following description, the receiver 6, the first expansion valve 7, the injection passage 11, and the electromagnetic valve 13 located relatively downstream on the main circuit 90 will be referred to as the downstream receiver 6a and the downstream first expansion valve 7a. , the downstream injection passage 11a, and the downstream electromagnetic valve 13a. Also, these devices positioned relatively upstream are called an upstream receiver 6b, an upstream first expansion valve 7b, an upstream injection passage 11b, and an upstream electromagnetic valve 13b.

The downstream injection channel 11a connects the downstream receiver 6a, the first compressor 1, and the check valve 18a. The upstream injection passage 11b connects the upstream receiver 6b, the second compressor 2a, and the check valve 18b.

Next, the operation when stopping the refrigeration apparatus 200 will be described. As shown in FIG. 4, prior to stopping, the control unit 80 first closes the first downstream expansion valve 7a. As a result, the refrigerant on the downstream side of the first downstream expansion valve 7a on the main circuit 90 is sequentially collected by the downstream receiver 6a.

After that, when it is detected that the downstream receiver 6a is filled with refrigerant, the controller 80 closes the upstream first expansion valve 7b and the downstream electromagnetic valve 13a, as shown in FIG. As a result, the downstream receiver 6 a is disconnected from the main circuit 90 . After that, the refrigerant still remaining on the main circuit 90 is stored in the upstream receiver 6b. Finally, when it is detected that the upstream receiver 6b is also filled with refrigerant, the controller 80 closes the second expansion valve 5 and the upstream electromagnetic valve 13b. As a result, the upstream receiver 6 b is also disconnected from the main circuit 90 . After that, the control unit 80 stops the first compressor 1 and the second compressors 2a and 2b. As described above, the refrigerating device 200 is stopped.

In this way, the refrigerant is stored in a plurality of receivers 6 sequentially from the receiver 6 on the downstream side to the receiver 6 on the upstream side, thereby recovering the refrigerant in the main circuit 90 and each device.

By the way, when the refrigerating device 200 is stopped as described above, the pressure inside the receiver 6 may rise due to the outside temperature. For example, consider a case where the pressure detection unit 62 detects that the pressure inside the downstream receiver 6a has become equal to or higher than a predetermined upper limit pressure. In this case, as shown in FIG. 6, the controller 80 opens only the downstream side solenoid valve 13a and the second expansion valve 5 . In this state, the controller 80 drives the first compressor 1 and the second compressors 2a and 2b. Then, the refrigerant in the downstream receiver 6a flows through the downstream injection channel 11a and the main circuit 90 toward the upstream receiver 6b. The control unit 80 continues this operation until the pressure in the downstream receiver 6a becomes less than the upper limit pressure.

As described above, according to the above configuration, in the refrigeration apparatus 200 having a plurality of receivers 6, the receivers 6 can be sequentially filled with refrigerant from the downstream side to the upstream side. Thereby, more refrigerant can be stored in the plurality of receivers 6 .

Further, according to the above configuration, when the pressure in the receiver 6 increases while the refrigerating apparatus 200 is stopped, the compressor is restarted while the injection flow path 11 connected to the receiver 6 located downstream is opened. By driving, the refrigerant in the receiver 6 positioned downstream can be transferred to another receiver 6 positioned upstream. Thereby, the pressure in each receiver 6 can be maintained below the upper limit pressure.

The embodiments of the present disclosure have been described above. Various changes and modifications can be made to the above configuration without departing from the gist of the present disclosure. For example, in each of the above embodiments, a two-stage compression refrigeration system 100 including the first compressor 1 and the second compressor 2, and a three-stage compression system including the first compressor 1 and the second compressors 2a and 2b The refrigerator 200 has been described. However, the number of compressors is not limited by the above embodiment, and it is possible to employ a configuration that performs four or more stages of compression. A specific example of a four-stage compression refrigeration system is a configuration using two scroll compressors. Even with such a configuration, it is possible to realize each operation described in the second embodiment.

[Appendix]
The refrigerating device 100 and the refrigerating device 200 described in each embodiment are understood, for example, as follows.

(1) A refrigeration apparatus 100 according to a first aspect includes a main circuit 90 as a circulation flow path through which a refrigerant flows, and a plurality of compressors (first compressor 1 and a second compressor 2), a check valve 18 arranged between the plurality of compressors, a condenser 4 arranged downstream of the plurality of compressors, and downstream of the condenser 4 The arranged receiver 6, the first expansion valve 7 arranged downstream of the receiver 6, the evaporator 8 arranged downstream of the first expansion valve 7, the receiver 6, the plurality of An injection passage 11 that connects the upstream side of the check valve 18 between the compressors, an electromagnetic valve 13 arranged on the injection passage 11, and the refrigerant stored in the receiver 6. and a control unit 80. The control unit 80 closes the first expansion valve 7 before stopping the compressor, and the liquid level The electromagnetic valve 13 is closed when the detection unit 61 detects that the amount of the liquid component in the receiver 6 has reached a predetermined upper limit.

According to the above configuration, prior to stopping the operation of the refrigeration system 100, the compressor is operated with the first expansion valve 7 closed, thereby removing the refrigerant existing in the main circuit 90 and each device. It can be collected in receiver 6 . Therefore, when the operation of the refrigerating apparatus 100 is stopped, it becomes difficult for the refrigerant to remain in the main circuit 90 and each device.

(2) The refrigeration system 200 according to the second aspect includes a plurality of sets of the receivers 6, the first expansion valves 7, the injection passages 11, and the electromagnetic valves 13 arranged in series on the main circuit 90. The control unit 80 closes the first expansion valve 7 before stopping the compressor, and the liquid level detection unit 61 detects that the amount of the liquid component in the receiver 6 reaches the upper limit value. When it is detected that the electromagnetic valve 13 has From the electromagnetic valve 13 to the first expansion valve 7 located on the most upstream side, and the electromagnetic valve 13 are sequentially carried out.

According to the above configuration, in the refrigerating apparatus 200 having a plurality of receivers 6, the receivers 6 can be sequentially filled with refrigerant from the downstream side to the upstream side. Thereby, more refrigerant can be stored in the plurality of receivers 6 .

(3) The refrigeration apparatus 200 according to the third aspect further includes a pressure detection section 62 that detects the pressure inside the receiver 6, and the control section 80 controls the pressure detection section 62 while the compressor is stopped. When it is detected that the pressure in the receiver 6 located relatively upstream among the plurality of receivers 6 is equal to or higher than a predetermined upper limit pressure, the receiver 6 located relatively upstream is detected by closing the electromagnetic valve 13 on the injection flow path 11 connected to the receiver 6 that While opening, the said compressor is driven.

Here, while the refrigeration system 200 is stopped, the pressure inside the receiver 6 may rise under the influence of the outside temperature. According to the above configuration, in such a case, by driving the compressor in a state in which the injection flow path 11 connected to the receiver 6 located downstream is open, of refrigerant can be transferred to another receiver 6 located upstream. Thereby, the pressure in each receiver 6 can be maintained below the upper limit pressure.

(4) The refrigerating apparatus 100 according to the fourth aspect further includes a second expansion valve 5 arranged between the condenser 4 and the receiver 6, and the control unit 80 controls the liquid level detection unit 61 When it is detected that the amount of refrigerant in the receiver 6 has reached a predetermined upper limit, the solenoid valve 13 and the second expansion valve 5 are closed.

According to the above configuration, by closing the second expansion valve 5 in addition to the electromagnetic valve 13, the receiver 6 is disconnected from the main circuit. Thereby, the refrigerant can be stably sealed in the receiver 6 .

According to the present disclosure, it is possible to provide a refrigeration system that can be manufactured at a lower cost.

100, 200 Refrigerating device 90 Main circuit 80 Control unit 1 First compressors 2, 2a, 2b Second compressor 4 Condenser 5 Second expansion valve 6 Receiver 6a Downstream receiver 6b Upstream receiver 7 First expansion valve 7a Downstream side first expansion valve 7b upstream side first expansion valve 8 evaporator 11 injection passage 11a downstream side injection passage 11b upstream side injection passage 13 solenoid valve 13a downstream side solenoid valve 13b upstream side solenoid valve 15 accumulators 18, 18a, 18b check valve

Claims (4)

a main circuit as a circulation channel through which the refrigerant flows;
a plurality of compressors arranged in series on the main circuit;
a check valve disposed between the plurality of compressors;
a condenser arranged downstream of the plurality of compressors;
a receiver located downstream of the condenser;
a first expansion valve located downstream of the receiver;
an evaporator located downstream of the first expansion valve;
an injection flow path connecting the receiver and an upstream side of the check valve between the plurality of compressors;
a solenoid valve arranged on the injection flow path;
a liquid level detection unit that detects the amount of the liquid component of the refrigerant stored in the receiver;
a control unit;
with
The control unit closes the first expansion valve before stopping the compressor, and the liquid level detection unit detects that the amount of the liquid component in the receiver has reached a predetermined upper limit. a refrigerating device that closes the solenoid valve when the A plurality of sets of the receiver, the first expansion valve, the injection passage, and the solenoid valve arranged in series on the main circuit,
The control unit closes the first expansion valve before stopping the compressor, and when the liquid level detection unit detects that the amount of the liquid component in the receiver has reached the upper limit. The control for closing the electromagnetic valves is performed by the first expansion valve of the plurality of sets, the first expansion valve located most downstream among the electromagnetic valves, and the first expansion valve located most upstream from the electromagnetic valve. 2. The refrigeration system according to claim 1, wherein the first expansion valve and the solenoid valve are sequentially operated. Further comprising a pressure detection unit that detects pressure in the receiver,
The control unit detects that the pressure in the receiver located relatively upstream among the plurality of receivers exceeds a predetermined upper limit pressure by the pressure detection unit while the compressor is stopped. is detected, the solenoid valve on the injection flow path connected to the receiver located relatively upstream is closed, and the injection connected to the receiver located relatively downstream 3. The refrigeration system according to claim 2, wherein the solenoid valve on the flow path is opened and the compressor is driven. further comprising a second expansion valve positioned between the condenser and the receiver;
The control unit closes the solenoid valve and the second expansion valve when the liquid level detection unit detects that the amount of the refrigerant in the receiver has reached a predetermined upper limit. 4. A refrigeration system according to any one of claims 1 to 3.

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