CN114341567B

CN114341567B - Outdoor unit and refrigeration cycle device

Info

Publication number: CN114341567B
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: 2024-01-02
Anticipated expiration: 2039-09-09
Also published as: JPWO2021048901A1; DK4030116T3; WO2021048901A1; FI4030116T3; JP7224480B2; EP4030116B1; EP4030116A4; CN114341567A; EP4030116A1; ES2964488T3

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), a liquid receiver (73), a flow rate adjustment valve (72), a heat exchanger (30), and a control device (100), which are arranged in this order in the 2 nd flow path (F2) from a branching point. 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). When the evacuation operation for recovering the refrigerant to the receiver (73) is started, the control device (100) is configured to control 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, and 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.

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 refrigerating apparatus having an intermediate injection flow path and a suction injection flow path. In the refrigeration apparatus, a part of the refrigerant flowing from the condenser to the evaporator can be merged into the medium-pressure refrigerant (intermediate pressure) of the compressor by using the intermediate injection flow path, or into the low-pressure refrigerant sucked into the compressor by using the suction injection flow path. Therefore, when the operation efficiency is deteriorated during the use of the intermediate injection flow path, the discharge temperature of the compressor can be lowered by using the suction injection flow path.

Prior art literature

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

Disclosure of Invention

The pump down operation is to provide an on-off valve or the like to a pipe through which a liquid refrigerant flows in the main refrigerant circuit, and to operate the compressor while shutting off the pipe, thereby moving the refrigerant from the load device to the outdoor unit and storing the refrigerant.

In the refrigeration apparatus described in japanese patent application laid-open No. 2014-01917 (patent document 1), when the flow of refrigerant on the indoor unit side is cut off and the evacuation operation is started on the load device side due to the load device being stopped, the refrigerant of the load device is recovered to the outdoor unit. At this time, when refrigerant recovery is performed 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, and the refrigerant is not easily liquefied in the condenser, and it takes time for recovering the refrigerant, and the time for the evacuation operation is prolonged.

The invention aims to provide an outdoor unit and a refrigeration cycle device, wherein the refrigerant recovery time is shortened during the evacuation operation.

The present disclosure relates to an outdoor unit of a refrigeration cycle apparatus configured to be connected to a load apparatus including a 1 st expansion device and an evaporator. The outdoor unit is provided with: a 1 st flow path that is 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 direction of refrigerant circulation, and return the refrigerant passing through the condenser to the compressor; the 2 nd expansion device, the liquid receiver and the flow rate regulating valve are arranged in the 2 nd flow path in sequence 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 arranged between the condenser of the 1 st passage and the branch point. The 2 nd passage of the heat exchanger is arranged between the flow rate adjusting 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 receiver. When the evacuation operation for recovering the refrigerant to the 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 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 the 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 refrigerant recovery is performed and the condensation temperature approaches the outside air temperature during the evacuation operation, the condensation of the refrigerant is performed 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 the 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 at the time of 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/closing valve; 30: a heat exchanger; 71: a 2 nd expansion valve; 50: a 1 st expansion valve; 60: an evaporator; 70: a throttle device; 72: a flow rate adjusting valve; 73: a liquid receiver; 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; and G2: a discharge port; and G3: a medium pressure port; h1: a 1 st path; h2: and a 2 nd passage.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following description will be given of a plurality of embodiments, but it is expected from the beginning of the application that the configurations described in the embodiments can be appropriately combined. 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 the respective devices 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 PI2. The load device 3 has a refrigerant outlet port PO3 for connection with the outdoor unit 2 and a refrigerant inlet port PI3. The piping 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 the load device 3. The outdoor unit 2 includes: the compressor 10, the condenser 20, the fan 22, the heat exchanger 30, and the pipes 80 to 82 and 89 each having the suction port G1, the discharge port G2, and the medium pressure port G3. The heat exchanger 30 is configured to have a 1 st passage H1 and a 2 nd passage H2, and to exchange 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, the pipes 85, 86, 87, and the on-off 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 the air in the cooling target space. 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 decompressing the refrigerant. The opening/closing valve 28 is closed (closed) when the load device 3 stops operating, and cuts off the refrigerant.

The compressor 10 compresses the refrigerant sucked from the pipe 89 and discharges the refrigerant to the pipe 80. The compressor 10 can arbitrarily change the driving frequency by inverter control. The compressor 10 is provided with a medium pressure port G3, and the refrigerant from the medium pressure port G3 can flow into the intermediate portion of 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 circulation amount of the refrigerant by adjusting the rotation speed of the compressor 10. Various types of compressors can be employed in the compressor 10, for example, a scroll type, a rotation 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 the outside air. By this heat exchange, the refrigerant is condensed and changes 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 supplying outside air is installed in the condenser 20. The fan 22 supplies the external air, which exchanges heat with the refrigerant in the condenser 20, to the condenser 20. By adjusting the rotation speed of the fan 22, the refrigerant pressure on the discharge side (high-pressure side pressure) of the compressor 10 can be adjusted.

Here, the refrigerant used in the refrigerant circuit of the refrigeration cycle apparatus 1 is CO ₂ However, in the case where a state where it is difficult to secure the supercooling degree is generated, other refrigerants may be used.

In the present specification, for ease of explanation, CO in a supercritical state will be described ₂ Such a case where the refrigerant is cooled is also referred to as a condenser 20. In this specification, for ease of explanation, the amount of decrease from the reference temperature of the supercritical refrigerant is also referred to as the supercooling degree.

The 1 st flow path F1 from the refrigerant inlet port PI2 to the refrigerant outlet port PO2 through the 1 st flow path H1 of the compressor 10, the condenser 20, and the heat exchanger 30 forms a circulation flow path for circulating the refrigerant together with the flow path 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: tubing 91, 92, 94 for flowing the refrigerant from the portion between the outlet of the 1 st path H1 and the refrigerant outlet port PO2 of the circulation path to the inlet of the 2 nd path H2; and a pipe 96 for allowing the refrigerant to flow from the outlet of the 2 nd passage H2 to the intermediate pressure port G3 of the compressor 10. Hereinafter, the 2 nd flow path F2, which branches from the main refrigerant circuit and feeds the refrigerant to the compressor 10 through the 2 nd flow path H2, is also referred to as an "injection flow path".

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

The pipe 91 branches from the main refrigerant circuit and flows the refrigerant into the 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 which is depressurized and becomes two phases can be separated in the container, the refrigerant can be stored, and the circulation amount of the refrigerant in the main refrigerant circuit can be adjusted. The exhaust 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 the refrigerant in the receiver 73 by adjusting the amount of the 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, the liquid receiver 73 contains a gas refrigerant, and therefore, the refrigerant temperature becomes a saturation temperature, and thus, when the liquid receiver 73 is disposed in the pipe 82, the supercooling degree cannot be ensured.

In addition, when the accumulator 73 is provided in the medium-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 medium-pressure liquid refrigerant can be stored in the accumulator 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 thinning the wall of the container.

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

The pressure sensor 110 detects the pressure PL of the suction port portion of the compressor 10, and outputs the detected value thereof to the control device 100. The pressure sensor 111 detects the discharge pressure PH of the compressor 10, and outputs the detected value 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 the 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 outside air temperature TA, which is the ambient temperature of the outdoor unit 2, and outputs the detected value to the control device 100.

In the present embodiment, the discharge temperature TH of the compressor 10 is controlled by flowing the refrigerant which is depressurized and becomes two phases into the compressor 10 in the 2 nd flow path F2. The amount of refrigerant in the main refrigerant circuit can be adjusted by the 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 by the heat exchanger 30.

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

(control during normal operation)

The control device 100 feedback-controls 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 the 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 intermediate pressure port G3 via the 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 intermediate pressure port G3 via the receiver 73 decreases, and the discharge temperature TH increases.

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

In this way, the control device 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.

In addition, the control device 100 performs feedback control of the flow rate adjustment valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 matches the target temperature in order to ensure the supercooling degree SC of the refrigerant at the outlet of the condenser 20 during the normal operation.

Fig. 3 is a flowchart for explaining the control of the flow rate adjustment valve 72. When the supercooling degree 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 greater than the target value (yes in S31), the control device 100 decreases the opening degree of the flow rate adjustment valve 72 (S32). As a result, the amount of liquid refrigerant discharged from the liquid receiver 73 decreases, and the amount of liquid refrigerant in the liquid receiver 73 increases, so that the amount of 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, when the supercooling degree 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 control device 100 increases the opening degree of the flow rate adjustment valve 72 (S34). As a result, the amount of liquid refrigerant discharged from the receiver 73 increases, the amount of liquid refrigerant stored in the receiver 73 decreases, the amount of refrigerant circulating in the main refrigerant circuit increases, the refrigerant temperature T1 decreases, and the degree of supercooling SC increases.

If the supercooling degree sc=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 control device 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)

In addition, the control device 100 performs feedback control of the flow rate adjustment valve 72 so that the temperature T1 of the refrigerant at the outlet of the condenser 20 coincides with the target temperature in order to ensure the supercooling degree SC of the refrigerant at the outlet of the condenser 20 during the normal operation, and closes the flow rate adjustment valve 72 to collect the liquid refrigerant to the receiver 73 during the evacuation operation.

The evacuation operation is to provide an on-off valve 28 or the like to the pipe 85 through which the liquid refrigerant flows in the main refrigerant circuit, and to operate the compressor 10 while cutting off the pipe 85, thereby moving the refrigerant from the load device 3 to the outdoor unit 2 and storing the refrigerant. The evacuation operation is performed, for example, by closing the 1 st expansion valve 50 before the stop operation or by closing the on-off valve 28 and then operating the compressor 10.

In general, a signal indicating 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 performed by continuing the normal operation when the pressure PL of the low-pressure portion detected by the pressure sensor 110 in the outdoor unit 2 decreases to the threshold value PA.

The following structure is adopted in the evacuation operation: if the on-off 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. The compressor 10 is configured not to pass the refrigerant in the stopped state, so that the refrigerant does not flow back to the load device 3.

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

In step S42, the control device 100 determines whether or not the refrigerant temperature T1 in the condenser 20 is lower than ta+α. Here, α represents a temperature difference at which the condensing efficiency of the refrigerant in the condenser 20 significantly decreases when the temperature difference between the refrigerant and the outside air becomes equal to or more than that, and is a value appropriately determined.

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

On the other hand, when T1< ta+α (yes in S42), the control device 100 increases the opening degree of the flow rate adjustment valve 72 slightly in step S44. Thereby, the liquid refrigerant stored in the 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 in the 2 nd passage H2 and the heat exchanger 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 in the 2 nd passage H2 and the heat exchanger is improved by 10 times or more. Thus, by condensing the refrigerant that is difficult to be condensed by the condenser 20 by the heat exchanger 30 in a stage where the recovery of the liquid refrigerant has progressed to some extent, the recovery of the liquid refrigerant can be advanced. Since the recovery amount of the liquid refrigerant does not increase when the opening degree of the flow rate adjustment valve 72 is excessively increased, the opening degree of the flow rate adjustment valve 72 in step S44 is set to be within a range in which the recovery amount of the liquid refrigerant in the receiver 73 increases.

Although not necessarily required, it is preferable that the control device 100 further increases the rotation speed of the compressor 10 in step S45. This can shorten the recovery time of the excess refrigerant that is difficult to condense due to the recovery progress.

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

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

By controlling in this way, at the 1 st time point when the evacuation operation is started, the control device 100 closes the flow rate adjustment valve 72 to store the liquid refrigerant in the receiver 73. Then, at the 2 nd time point when the amount of the liquid refrigerant in the receiver 73 increases and the efficiency of the condenser 20 decreases, the control device 100 slightly opens the flow rate adjustment valve 72 to improve the efficiency of the heat exchanger 30 and promote condensation of the refrigerant in the 1 st path H1. This can shorten the time until the evacuation operation is completed.

Finally, the present embodiment will be 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 apparatus 3 including a 1 st expansion valve 50 corresponding to a "1 st expansion device" and an evaporator 60. The outdoor unit 2 includes: the 1 st flow path F1 is connected to the load device 3 to form a circulation flow path for circulating the refrigerant; the compressor 10 and the condenser 20 are disposed in the 1 st flow path F1; the 2 nd flow path F2 is configured to branch from a branching point of the 1 st flow path F1 downstream of the condenser 20 in the direction of refrigerant circulation, and return the refrigerant passing through the condenser 20 to the compressor 10; a 2 nd expansion valve 71, a receiver 73, and a flow rate adjustment valve 72, which correspond to the "2 nd expansion device", are disposed in the 2 nd flow path F2 in this order from the branching point; a heat exchanger 30 configured to have a 1 st passage H1 and a 2 nd passage H2 and 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 arranged between the condenser 20 of the 1 st passage F1 and the branch point. 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 the discharge flow rate of the liquid refrigerant from the receiver 73.

The control device 100 is configured to control the compressor 10 and the flow rate adjustment valve 72. When the evacuation operation for recovering the refrigerant to the receiver 73 is started, the control device 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 control device 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 a 2 nd time point after the 1 st time point in the evacuation operation.

When the evacuation operation is performed, the refrigerant is recovered to the receiver 73, and therefore the amount of the liquid refrigerant in the receiver 73 gradually increases. Therefore, the amount of the liquid refrigerant of the receiver 73 at the time 2 is larger than the amount of the liquid refrigerant of the receiver 73 at the time 1.

Preferably, the control device 100 controls the control states 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 the threshold value. Accordingly, in the stage of recovering the liquid refrigerant to the receiver 73, even when the difference between the refrigerant temperature T1 in the condenser 20 and the outside air temperature TA becomes small and the efficiency of the condenser 20 decreases, the efficiency of the heat exchanger 30 can be improved to further advance the recovery of the liquid refrigerant.

Further, 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 by a slight opening degree of the degree of occurrence of the annular flow of the liquid refrigerant in the 2 nd passage H2 of the heat exchanger 30, or by a degree of repetition of opening and closing for a short period of time. This improves the efficiency of heat exchange in the heat exchanger 30, and the refrigerant passing through the 1 st path H1 condenses in the heat exchanger 30, thereby promoting recovery of the liquid refrigerant.

More preferably, the control device 100 is configured to make 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 recovery time of the excess refrigerant that is difficult to condense due to the recovery progress.

While the present embodiment has been described above by way of example with respect to a refrigerator including the refrigeration cycle apparatus 1, the refrigeration cycle apparatus 1 may be used in an air conditioner or the like.

It should be understood that the embodiments disclosed herein are illustrative only and not limiting in all respects. The scope of the present invention is defined by the appended claims rather than the description of the embodiments described above, and is intended to include meaning 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 apparatus including a 1 st expansion device and an evaporator, the outdoor unit comprising:

a 1 st flow path that is connected to the 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 branching point of the 1 st flow path downstream of the condenser in a direction of the refrigerant cycle, 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 disposed in the 2 nd flow path in this order from the branching point;

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

a control device configured to control the compressor and the flow rate adjustment valve,

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

the 2 nd passage of the heat exchanger is arranged between the flow rate adjusting 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 receiver,

when the evacuation operation for recovering the refrigerant to the receiver is started, the control device controls the control state of the compressor and the flow rate adjustment valve to be the 1 st state in which the compressor is operated and the flow rate adjustment valve is closed at the 1 st point in time,

at a 2 nd time point after the 1 st time point in the evacuation operation, the control device controls to shift the control state 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, wherein,

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

3. The outdoor unit of claim 2, wherein,

the control device controls such that the rotational speed of the compressor in the 2 nd state is higher than the rotational speed of the compressor in the 1 st state.

4. The outdoor unit of claim 1, wherein,

the amount of liquid refrigerant of the liquid receiver at the 2 nd time point is greater than the amount of liquid refrigerant of the liquid receiver 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.