CN114341567A

CN114341567A - Outdoor unit and refrigeration cycle device

Info

Publication number: CN114341567A
Application number: CN201980099962.8A
Authority: CN
Inventors: 石川智隆; 有井悠介; 早坂素
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2019-09-09
Filing date: 2019-09-09
Publication date: 2022-04-12
Anticipated expiration: 2039-09-09
Also published as: FI4030116T3; JP7224480B2; EP4030116B1; CN114341567B; WO2021048901A1; JPWO2021048901A1; DK4030116T3; EP4030116A4; ES2964488T3; EP4030116A1

Abstract

The outdoor unit (2) is provided with a 1 st flow path (F1), a 2 nd flow path (F2), a 2 nd expansion device (71) disposed in the 2 nd flow path (F2) in this order from a branching point, a liquid receiver (73), a flow rate adjustment valve (72), a heat exchanger (30), and a control device (100). The heat exchanger (30) exchanges heat between the refrigerant flowing through the 1 st passage (H1) and the refrigerant flowing through the 2 nd passage (H2). The control device (100) is configured to, when starting an evacuation operation for recovering refrigerant to a liquid receiver (73), control the control states of the compressor (10) and the flow rate adjustment valve (72) to a 1 st state in which the compressor (10) is operated and the flow rate adjustment valve (72) is closed at a 1 st point in time, and to shift from the 1 st state to a 2 nd state in which the compressor (10) is operated and the flow rate adjustment valve (72) is opened at a 2 nd point in time after the 1 st point in the evacuation operation.

Description

Outdoor unit and refrigeration cycle device

Technical Field

The present invention relates to an outdoor unit and a refrigeration cycle apparatus.

Background

Japanese patent application laid-open No. 2014-01917 (patent document 1) discloses a refrigeration apparatus having an intermediate injection passage and a suction injection passage. In this refrigeration apparatus, a part of the refrigerant flowing from the condenser to the evaporator can be joined to a medium-pressure (intermediate pressure) refrigerant of the compressor by using the intermediate injection flow path, or joined to a low-pressure refrigerant sucked into the compressor by using the suction injection flow path. Therefore, when the operation efficiency is deteriorated in the intermediate injection passage, the discharge temperature of the compressor can be lowered by using the suction injection passage.

Documents of the prior art

Patent document 1: japanese patent laid-open publication No. 2014-01917

Disclosure of Invention

The pump down operation is a operation in which an on-off valve or the like is provided in a pipe through which a liquid refrigerant flows in the main refrigerant circuit, and the refrigerant is moved from the load device to the outdoor unit and stored by operating the compressor in a state in which the pipe is cut off.

In the refrigeration apparatus described in japanese patent application laid-open No. 2014-01917 (patent document 1), when the flow of the refrigerant in the indoor unit is shut off due to the load device being stopped or the like and the evacuation operation starts to be performed in the load device side, the refrigerant in the load device is recovered to the outdoor unit. In this case, when the refrigerant is recovered and the refrigerant in the high-pressure portion is reduced, there is a problem as follows: the condensing temperature is close to the outside air temperature, the refrigerant is not easily liquefied in the condenser, time is taken for recovering the refrigerant, and the evacuation operation time is prolonged.

The purpose of the present invention is to provide an outdoor unit and a refrigeration cycle device in which the refrigerant recovery time during evacuation operation is shortened.

The present disclosure relates to an outdoor unit of a refrigeration cycle apparatus configured to be connected to a load device including a 1 st expansion device and an evaporator. The outdoor unit is provided with: a 1 st flow path connected to a load device to form a circulation flow path for circulating a refrigerant; a compressor and a condenser disposed in the 1 st flow path; a 2 nd flow path configured to branch from a branch point of the 1 st flow path downstream of the condenser in a refrigerant circulation direction and return the refrigerant passing through the condenser to the compressor; a 2 nd expansion device, a liquid receiver, and a flow rate adjustment valve, which are arranged in the 2 nd flow path in this order from the branch point; and a heat exchanger configured to have a 1 st passage and a 2 nd passage and to exchange heat between the refrigerant flowing through the 1 st passage and the refrigerant flowing through the 2 nd passage. The 1 st passage of the heat exchanger is disposed between the condenser and the branch point of the 1 st passage. The 2 nd passage of the heat exchanger is disposed between the flow rate adjustment valve of the 2 nd passage and the compressor. The flow rate adjustment valve is configured to adjust a discharge flow rate of the liquid refrigerant from the liquid receiver. When the evacuation operation for recovering the refrigerant to the liquid receiver is started, the control state of the compressor and the flow rate adjustment valve is set to the 1 st state in which the compressor is operated and the flow rate adjustment valve is closed at the 1 st time. At a 2 nd time point after the 1 st time point in the evacuation operation, the control state is shifted from the 1 st state to a 2 nd state in which the compressor is operated and the flow rate adjustment valve is opened.

According to the outdoor unit of the present disclosure, even when the refrigerant is recovered during the evacuation operation and the condensation temperature is close to the outside air temperature, the refrigerant is condensed while maintaining the efficiency of the heat exchanger. Therefore, the time required for refrigerant recovery can be shortened.

Drawings

Fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to the present embodiment.

Fig. 2 is a flowchart for explaining control of the 2 nd expansion valve 71.

Fig. 3 is a flowchart for explaining the control of the flow rate adjustment valve 72.

Fig. 4 is a flowchart for explaining control during the evacuation operation.

(symbol description)

1: a refrigeration cycle device; 2: an outdoor unit; 3: a load device; 10: a compressor; 20: a condenser; 22: a fan; 28: an opening and closing valve; 30: a heat exchanger; 71: a 2 nd expansion valve; 50: 1 st expansion valve; 60: an evaporator; 70: a device; 72: a flow rate regulating valve; 73: a liquid receiver; 74: a flow path switching unit; 80. 81, 82, 83, 84, 85, 88, 89, 91, 92, 94, 96: piping; 93: an exhaust pipe; 100: a control device; 104: a memory; 110. 111: a pressure sensor; 120. 121, 122, 123: a temperature sensor; f1: a 1 st flow path; f2: a 2 nd flow path; g1: a suction port; g2: a discharge port; g3: a medium pressure port; h1: a 1 st path; h2: and (2) a 2 nd path.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. A plurality of embodiments will be described below, but it is anticipated that the configurations described in the embodiments can be appropriately combined from the beginning of the application. In the drawings, the same or corresponding portions are denoted by the same reference numerals, and description thereof will not be repeated.

Fig. 1 is an overall configuration diagram of a refrigeration cycle apparatus according to the present embodiment. In fig. 1, the connection relationship and arrangement structure of each device in the refrigeration cycle apparatus are functionally shown, and the arrangement in the physical space is not necessarily shown.

Referring to fig. 1, the refrigeration cycle apparatus 1 includes an outdoor unit 2, a load device 3, and

pipes

84 and 88. The outdoor unit 2 has a refrigerant outlet port PO2 for connection with the load device 3 and a refrigerant inlet port PI 2. The load device 3 has a refrigerant outlet port PO3 for connection with the outdoor unit 2 and a refrigerant inlet port PI 3. The pipe 84 connects the refrigerant outlet port PO2 of the outdoor unit 2 and the refrigerant inlet port PI3 of the load device 3. The pipe 88 connects the refrigerant outlet port PO3 of the load device 3 and the refrigerant inlet port PI2 of the outdoor unit 2.

The outdoor unit 2 of the refrigeration cycle apparatus 1 is connected to a load device 3. The outdoor unit 2 includes: the compressor 10 includes a suction port G1, a discharge port G2, and a medium-pressure port G3, a condenser 20, a fan 22, a heat exchanger 30, and pipes 80 to 82, 89. The heat exchanger 30 includes the 1 st passage H1 and the 2 nd passage H2, and exchanges heat between the refrigerant flowing through the 1 st passage H1 and the refrigerant flowing through the 2 nd passage H2.

The load device 3 includes the 1 st expansion valve 50, the evaporator 60,

pipes

85, 86, 87, and the opening/closing valve 28. The evaporator 60 is configured to exchange heat between air and refrigerant. In the refrigeration cycle apparatus 1, the evaporator 60 evaporates the refrigerant by absorbing heat from air in the space to be cooled. The 1 st expansion valve 50 is, for example, a temperature expansion valve controlled independently of the outdoor unit 2. The 1 st expansion valve 50 may be an electronic expansion valve capable of reducing the pressure of the refrigerant. The on-off valve 28 is closed (closed) when the load device 3 stops operating, and cuts off the refrigerant.

The compressor 10 compresses a refrigerant sucked from a pipe 89 and discharges the refrigerant to a pipe 80. The compressor 10 can arbitrarily change the drive frequency by inverter control. The compressor 10 is provided with the intermediate pressure port G3, and the refrigerant from the intermediate pressure port G3 can flow into the compressor during the compression process. The compressor 10 is configured to adjust the rotation speed in accordance with a control signal from the control device 100. The capacity of the refrigeration cycle apparatus 1 can be adjusted by adjusting the rotation speed of the compressor 10 to adjust the circulation amount of the refrigerant. Various types of compressors can be employed in the compressor 10, for example, a rolling type, a rotary type, a screw type, or the like can be employed.

The condenser 20 is configured to exchange heat (dissipate heat) between the high-temperature and high-pressure gas refrigerant discharged from the compressor 10 and outside air. By this heat exchange, the refrigerant is condensed to change to a liquid phase. The refrigerant discharged from the compressor 10 to the pipe 80 is condensed and liquefied in the condenser 20 and flows out to the pipe 81. In order to improve the efficiency of heat exchange, a fan 22 for feeding outside air is installed in the condenser 20. The fan 22 supplies the outside air heat-exchanged with the refrigerant in the condenser 20 to the condenser 20. The refrigerant pressure on the discharge side (high-pressure side pressure) of the compressor 10 can be adjusted by adjusting the rotation speed of the fan 22.

Here, the refrigerant used in the refrigerant circuit of the refrigeration cycle apparatus 1 is CO₂However, in the case where a state in which it is difficult to ensure the degree of supercooling occurs, another refrigerant may be used.

In addition, in the present specification, for ease of explanation, CO in a supercritical state will be referred to₂Such a cooling operation by the refrigerant is also performedReferred to as the condenser 20. In the present specification, for the sake of easy description, the amount of decrease of the supercritical refrigerant from the reference temperature is also referred to as the supercooling degree.

The 1 st flow path F1 extending from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 via the compressor 10, the condenser 20, and the 1 st passage H1 of the heat exchanger 30 forms a circulation flow path through which the refrigerant circulates together with the 1 st flow path F1 of the load device 3 in which the 1 st expansion valve 50 and the evaporator 60 are disposed. Hereinafter, this circulation flow path is also referred to as a "main refrigerant circuit" of the refrigeration cycle.

The outdoor unit 2 further includes:

pipes

91, 92, and 94 for allowing the refrigerant to flow from a portion of the circulation flow path between the outlet of the 1 st passage H1 and the refrigerant outlet port PO2 to the inlet of the 2 nd passage H2; and a pipe 96 that allows the refrigerant to flow from the outlet of the 2 nd passage H2 to the suction port G1 or the intermediate-pressure port G3 of the compressor 10. Hereinafter, the 2 nd flow path F2 that branches from the main refrigerant circuit and feeds the refrigerant to the compressor 10 via the 2 nd flow path H2 is also referred to as an "injection flow path".

The outdoor unit 2 further includes a liquid receiver (receiver) 73 disposed in the 2 nd flow path F2 and storing the refrigerant. The 2 nd expansion valve 71 is disposed between a pipe 91 branched from a portion between the outlet of the 1 st passage H1 and the refrigerant outlet port PO2 of the circulation flow path and a pipe 92 connected to the inlet of the liquid receiver 73. The outdoor unit 2 further includes: an exhaust pipe 93 connecting the gas discharge port of the liquid receiver 73 and the 2 nd passage H2 to discharge the refrigerant gas in the liquid receiver 73; an expansion device 70 disposed between the exhaust pipe 93 and a pipe 94 leading to a 2 nd passage H2; and a flow rate adjustment valve 72 that adjusts the flow rate of the refrigerant in the pipe 94 connected to the liquid refrigerant discharge port of the liquid receiver 73.

The pipe 91 branches from the main refrigerant circuit and allows the refrigerant to flow into the liquid receiver 73. The 2 nd expansion valve 71 is an electronic expansion valve capable of reducing the refrigerant in the high-pressure portion of the main refrigerant circuit to an intermediate pressure. The liquid receiver 73 is a container as follows: the gas phase and the liquid phase of the refrigerant that has been depressurized and has become two phases can be separated in the container, and the refrigerant can be stored to adjust the circulation amount of the refrigerant in the main refrigerant circuit. The discharge pipe 93 connected to the upper portion of the liquid receiver 73 and the pipe 94 connected to the lower portion of the liquid receiver 73 are pipes for taking out the refrigerant separated into the gas refrigerant and the liquid refrigerant in the liquid receiver 73 in a separated state. The flow rate adjustment valve 72 can adjust the amount of refrigerant in the liquid receiver 73 by adjusting the amount of liquid refrigerant discharged from the pipe 94.

By providing the liquid receiver 73 in the injection flow path in this way, the degree of supercooling in the pipes 82 and 83 as liquid pipes can be easily ensured. This is because, in general, since the liquid receiver 73 contains a gas refrigerant, the refrigerant temperature becomes a saturation temperature, and therefore, the degree of supercooling cannot be ensured when the liquid receiver 73 is disposed in the pipe 82.

In addition, when the liquid receiver 73 is provided in the intermediate-pressure portion, even when the pressure of the high-pressure portion of the main refrigerant circuit is high and the refrigerant is in a supercritical state, the liquid refrigerant of the intermediate pressure can be stored in the liquid receiver 73. Therefore, the design pressure of the container of the liquid receiver 73 can be made lower than that of the high-pressure portion, and the cost can be reduced by making the wall of the container thin.

The outdoor unit 2 further includes: pressure sensors 110 and 111, temperature sensors 120 to 123, and a controller 100 for controlling the compressor 10, the 2 nd expansion valve 71, and the flow rate adjustment valve 72.

The pressure sensor 110 detects a pressure PL of a suction port portion of the compressor 10, and outputs a detection value thereof to the control device 100. The pressure sensor 111 detects the discharge pressure PH of the compressor 10, and outputs a detection value thereof to the control device 100.

The temperature sensor 120 detects the discharge temperature TH of the compressor 10, and outputs the detected value to the control device 100. The temperature sensor 121 detects the refrigerant temperature T1 of the pipe 81 at the outlet of the condenser 20, and outputs the detected value to the control device 100. The temperature sensor 122 detects a refrigerant temperature T2 at the outlet of the 1 st passage H1 on the cooled side of the heat exchanger 30, and outputs the detected value to the control device 100. The temperature sensor 123 detects an ambient temperature of the outdoor unit 2, that is, an outside air temperature TA, and outputs a detection value thereof to the control device 100.

In the present embodiment, the 2 nd flow path F2 controls the discharge temperature TH of the compressor 10 by causing the two-phase refrigerant that has been depressurized to flow into the compressor 10. The refrigerant amount in the main refrigerant circuit can be adjusted by the liquid receiver 73 provided in the 2 nd flow path F2. The 2 nd flow path F2 also ensures supercooling of the refrigerant in the main refrigerant circuit by heat exchange in the heat exchanger 30.

The control device 100 includes a CPU (Central Processing Unit) 102, a Memory 104 (a ROM (Read Only Memory) and a RAM (Random Access Memory)), an input/output buffer (not shown) for inputting/outputting various signals, and the like. The CPU102 expands and executes a program stored in the ROM in the RAM or the like. The program stored in the ROM is a program describing a processing procedure of the control device 100. The control device 100 executes control of each device in the outdoor unit 2 in accordance with these programs. The control is not limited to the processing performed by software, and may be performed by dedicated hardware (electronic circuit).

(control during normal operation)

The control device 100 performs feedback control on the 2 nd expansion valve 71 so that the discharge temperature TH of the compressor 10 matches the target temperature.

Fig. 2 is a flowchart for explaining control of the 2 nd expansion valve 71. When the discharge temperature TH of the compressor 10 is higher than the target temperature (yes in S21), the control device 100 increases the opening degree of the 2 nd expansion valve 71 (S22). As a result, the refrigerant flowing into the medium-pressure port G3 via the liquid receiver 73 increases, and the discharge temperature TH decreases.

On the other hand, when the discharge temperature TH of the compressor 10 is lower than the target temperature (no in S21 and yes in S23), the control device 100 decreases the opening degree of the 2 nd expansion valve 71 (S24). As a result, the refrigerant flowing into the medium-pressure port G3 via the liquid receiver 73 decreases, and the discharge temperature TH increases.

If the discharge temperature TH is equal to the target temperature (no in S21 and no in S23), the control device 100 maintains the opening degree of the 2 nd expansion valve 71 in the current state.

In this way, the controller 100 controls the opening degree of the 2 nd expansion valve 71 so that the discharge temperature TH of the compressor 10 approaches the target temperature.

Further, the controller 100 feedback-controls the flow rate adjustment valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 matches the target temperature in order to ensure the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 during normal operation.

Fig. 3 is a flowchart for explaining the control of the flow rate adjustment valve 72. When the degree of supercooling SC determined from the refrigerant temperature T1 at the outlet of the condenser 20 and the pressure (approximated by PH) of the condenser 20 is larger than the target value (yes in S31), the controller 100 decreases the opening degree of the flow rate adjustment valve 72 (S32). As a result, the amount of the liquid refrigerant discharged from the liquid receiver 73 decreases, and the amount of the liquid refrigerant in the liquid receiver 73 increases, so that the amount of the refrigerant circulating in the main refrigerant circuit decreases, and the refrigerant temperature T1 increases, and the degree of supercooling SC decreases.

On the other hand, if the degree of supercooling SC determined from the refrigerant temperature T1 at the outlet of the condenser 20 and the pressure of the condenser 20 (approximated by PH) is smaller than the target value (no in S31 and yes in S33), the controller 100 increases the opening degree of the flow rate adjustment valve 72 (S34). As a result, the amount of the liquid refrigerant discharged from the liquid receiver 73 increases, and the amount of the liquid refrigerant accumulated in the liquid receiver 73 decreases, so that the amount of the refrigerant circulating in the main refrigerant circuit increases, and the refrigerant temperature T1 decreases, and therefore the degree of supercooling SC increases.

If the degree of subcooling SC is equal to the target value (no in S31 and no in S33), the control device 100 maintains the opening degree of the flow rate adjustment valve 72 in the current state.

In this way, the controller 100 controls the opening degree of the flow rate adjustment valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 approaches the target temperature.

(control during evacuation operation)

Further, the controller 100 performs feedback control of the flow rate adjustment valve 72 so that the refrigerant temperature T1 at the outlet of the condenser 20 matches the target temperature in order to ensure the degree of subcooling SC of the refrigerant at the outlet of the condenser 20 during normal operation, and closes the flow rate adjustment valve 72 during evacuation operation to recover the liquid refrigerant to the liquid receiver 73.

The evacuation operation is performed by providing an on-off valve 28 or the like to the pipe 85 through which the liquid refrigerant flows in the main refrigerant circuit, and operating the compressor 10 while the pipe 85 is shut off, thereby moving the refrigerant from the load device 3 to the outdoor unit 2 and storing the refrigerant. The evacuation operation is performed by, for example, closing the 2 nd expansion valve 40 before the operation is stopped, or operating the compressor 10 after the opening/closing valve 28 is closed.

In general, the signal instructing the start of the evacuation operation is not particularly transmitted from the load device 3 side to the outdoor unit 2, and the evacuation operation is executed by continuing the normal operation when the pressure PL of the low-pressure portion detected by the pressure sensor 110 decreases to the threshold PA in the outdoor unit 2.

The structure in the evacuation operation is as follows: if the opening/closing valve 28 is closed and the pressure PL of the low pressure portion detected by the pressure sensor 110 decreases to the threshold value PB, the control device 100 stops the compressor 10 to stop the evacuation. Since the compressor 10 is configured not to pass the refrigerant in the stopped state, the refrigerant does not flow back to the load device 3.

Fig. 4 is a flowchart for explaining control during the evacuation operation. First, in step S41, control device 100 determines whether or not pressure PL of the low pressure portion detected by pressure sensor 110 is lower than threshold PA. If PL < threshold PA is satisfied (yes in S41), the evacuation operation is executed after step S42. On the other hand, if PL < threshold PA is not satisfied (no in S41), the evacuation operation is not executed, and the control returns to the normal operation in step S47.

In step S42, the control device 100 determines whether the refrigerant temperature T1 in the condenser 20 is lower than TA + α. Here, α represents a temperature difference in which the efficiency of condensation of the refrigerant in the condenser 20 significantly decreases when the temperature difference between the refrigerant and the outside air becomes smaller or larger, and is an appropriately determined value.

If not T1< TA + α (no in S42), the controller 100 closes the flow rate adjustment valve 72 in step S43. Thereby, the gas refrigerant is discharged from the liquid receiver 73 through the discharge pipe 93, and the liquid refrigerant is recovered in the liquid receiver 73.

On the other hand, when T1 is < TA + α (yes in S42), the controller 100 slightly increases the opening degree of the flow rate adjustment valve 72 in step S44. Thereby, the liquid refrigerant accumulated in the liquid receiver 73 flows to the 2 nd passage H2 of the heat exchanger 30. When the flow rate adjustment valve 72 is closed, the gas refrigerant flows through the exhaust pipe 93 in the 2 nd passage H2 of the heat exchanger 30. In the state where the gas refrigerant flows, the heat transfer rate between the refrigerant and the heat exchanger in the 2 nd passage H2 is low.

Here, if the liquid refrigerant is mixed by slightly opening the flow rate adjustment valve 72, the heat transfer rate between the refrigerant and the heat exchanger in the 2 nd passage H2 is improved by 10 times or more. Thus, the refrigerant that is difficult to condense in the condenser 20 is condensed by the heat exchanger 30 at a stage when the liquid refrigerant is recovered to some extent, and the recovery of the liquid refrigerant can be advanced. Since the amount of liquid refrigerant collected does not increase when the opening degree of the flow rate adjustment valve 72 is made too large, the opening degree of the flow rate adjustment valve 72 in step S44 is set to be within the range in which the amount of liquid refrigerant collected in the liquid receiver 73 increases.

Although not necessarily required, the controller 100 preferably increases the rotation speed of the compressor 10 in step S37. This can shorten the time required for recovering the excess refrigerant that has progressed and is difficult to condense.

Next, in step S46, control device 100 determines whether or not pressure PL of the low pressure portion detected by pressure sensor 110 has decreased to threshold PB. The threshold PB is a value lower than the threshold PA and is a determination value for determining completion of refrigerant collection by the load device 3. When the pressure PL has not decreased to the threshold PB (no in S46), the control device 100 continues the operation of the compressor 10 and continues the evacuation operation.

On the other hand, when the pressure PL decreases to the threshold PB (yes in S46), the control device 100 stops the compressor 10 and ends the evacuation in step S47.

By this control, at the 1 st time point when the evacuation operation is started, the controller 100 closes the flow rate adjustment valve 72 to accumulate the liquid refrigerant in the liquid receiver 73. At the 2 nd timing when the amount of the liquid refrigerant in the liquid receiver 73 increases and the efficiency of the condenser 20 decreases, the controller 100 slightly opens the flow rate adjustment valve 72 to improve the efficiency of the heat exchanger 30, thereby promoting the condensation of the refrigerant in the 1 st passage H1. This can shorten the time until the evacuation operation is completed.

Finally, the present embodiment is summarized again with reference to the drawings. As shown in fig. 1, the present disclosure relates to an outdoor unit 2 of a refrigeration cycle apparatus 1 configured to be connected to a load device 3 including a 1 st expansion valve 50 corresponding to a "1 st expansion device" and an evaporator 60. The outdoor unit 2 includes: a 1 st flow path F1 forming a circulation flow path through which the refrigerant circulates by being connected to the load device 3; a compressor 10 and a condenser 20 disposed in the 1 st flow path F1; a 2 nd flow path F2 branching from a branch point of the 1 st flow path F1 downstream of the condenser 20 in the refrigerant circulation direction, and configured to return the refrigerant passing through the condenser 20 to the compressor 10; a 2 nd expansion valve 71, a liquid receiver 73, and a flow rate adjustment valve 72 corresponding to the "2 nd expansion device" are disposed in the 2 nd flow path F2 in this order from the branch point; a heat exchanger 30 having a 1 st passage H1 and a 2 nd passage H2, and configured to exchange heat between the refrigerant flowing through the 1 st passage H1 and the refrigerant flowing through the 2 nd passage H2; and a control device 100.

The 1 st passage H1 of the heat exchanger 30 is disposed between the condenser 20 and the branch point of the 1 st passage F1. The 2 nd passage H2 of the heat exchanger 30 is disposed between the flow rate adjustment valve 72 of the 2 nd passage F2 and the compressor 10. The flow rate adjustment valve 72 is configured to adjust a discharge flow rate of the liquid refrigerant from the liquid receiver 73.

The controller 100 is configured to control the compressor 10 and the flow rate adjustment valve 72. When starting the evacuation operation of recovering the refrigerant to the liquid receiver 73, the controller 100 controls the control states of the compressor 10 and the flow rate adjustment valve 72 to the 1 st state in which the compressor 10 is operated and the flow rate adjustment valve 72 is closed at the 1 st time point. The controller 100 is configured to transition from the 1 st state to the 2 nd state in which the compressor 10 is operated and the flow rate adjustment valve 72 is opened at the 2 nd time point after the 1 st time point in the evacuation operation.

During the evacuation operation, the amount of the liquid refrigerant in the liquid receiver 73 gradually increases because the refrigerant is recovered into the liquid receiver 73. Therefore, the amount of the liquid refrigerant in the liquid receiver 73 at the 2 nd time point is larger than the amount of the liquid refrigerant in the liquid receiver 73 at the 1 st time point.

Preferably, the control device 100 controls the control state of the compressor 10 and the flow rate adjustment valve 72 to the 2 nd state when the difference between the condensation temperature of the refrigerant in the condenser 20 and the outside air temperature is smaller than a threshold value. Thus, even when the difference between the refrigerant temperature T1 in the condenser 20 and the outside air temperature TA is small and the efficiency of the condenser 20 is reduced at the stage of recovering the liquid refrigerant to the liquid receiver 73, the efficiency of the heat exchanger 30 can be improved to further promote the recovery of the liquid refrigerant.

When the opening degree of the flow rate adjustment valve 72 in the 2 nd state is fully opened for a long time, the amount of the liquid refrigerant in the liquid receiver 73 decreases. Therefore, in the 2 nd state, the flow rate adjustment valve 72 is preferably opened to a slight degree of opening to the extent that the annular flow of the liquid refrigerant occurs in the 2 nd passage H2 of the heat exchanger 30, or to the extent that the opening and closing are repeated for a short time. This improves the heat exchange efficiency of the heat exchanger 30, and the refrigerant passing through the 1 st passage H1 in the heat exchanger 30 condenses, thereby promoting the recovery of the liquid refrigerant.

More preferably, the controller 100 is configured to set the rotation speed of the compressor 10 in the 2 nd state higher than the rotation speed of the compressor 10 in the 1 st state. This can shorten the time required for recovering the excess refrigerant that has progressed and is difficult to condense.

The present embodiment has been described above by exemplifying a refrigerator including the refrigeration cycle device 1, but the refrigeration cycle device 1 may be used in an air conditioner or the like.

It should be understood that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims rather than the description of the above embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope.

Claims

1. An outdoor unit of a refrigeration cycle apparatus configured to be connected to a load device including a 1 st expansion device and an evaporator, the outdoor unit comprising:

a 1 st flow path connected to the load device to form a circulation flow path through which a refrigerant circulates;

a compressor and a condenser disposed in the 1 st flow path;

a 2 nd flow path which is branched from a branch point of the 1 st flow path downstream of the condenser in the refrigerant circulation direction and is configured to return the refrigerant passing through the condenser to the compressor;

a 2 nd expansion device, a liquid receiver, and a flow rate adjustment valve, which are disposed in the 2 nd flow path in this order from the branch point; and

a heat exchanger configured to have a 1 st passage and a 2 nd passage and to exchange heat between the refrigerant flowing through the 1 st passage and the refrigerant flowing through the 2 nd passage,

the 1 st passage of the heat exchanger is disposed between the condenser and the branch point of the 1 st passage,

the 2 nd passage of the heat exchanger is disposed between the flow rate adjustment valve of the 2 nd flow path and the compressor,

the flow rate adjustment valve is configured to adjust a discharge flow rate of the liquid refrigerant from the liquid receiver,

when starting the evacuation operation of recovering the refrigerant to the liquid receiver, the control state of the compressor and the flow rate adjustment valve is set to the 1 st state in which the compressor is operated and the flow rate adjustment valve is closed at the 1 st time point,

at a 2 nd time point after the 1 st time point in the evacuation operation, the control state is shifted from the 1 st state to a 2 nd state in which the compressor is operated and the flow rate adjustment valve is opened.

2. The outdoor unit of claim 1,

when the difference between the condensing temperature of the refrigerant in the condenser and the outside air temperature is smaller than a threshold value, the control state of the compressor and the flow rate adjustment valve is the 2 nd state.

3. The outdoor unit of claim 2,

the rotation speed of the compressor in the 2 nd state is higher than that in the 1 st state.

4. The outdoor unit of claim 1,

the amount of liquid refrigerant of the liquid accumulator at the 2 nd time point is greater than the amount of liquid refrigerant of the liquid accumulator at the 1 st time point.

5. A refrigeration cycle device is provided with:

an outdoor unit according to any one of claims 1 to 4; and

the load device.