WO2020164212A1

WO2020164212A1 - Refrigerant circulation system and control method thereof, and air conditioner

Info

Publication number: WO2020164212A1
Application number: PCT/CN2019/091887
Authority: WO
Inventors: 张仕强; 武连发; 袁国炉; 李立民; 曹朋
Original assignee: 珠海格力电器股份有限公司
Priority date: 2019-02-12
Filing date: 2019-06-19
Publication date: 2020-08-20
Also published as: CN109682106A; CN109682106B

Abstract

A refrigerant circulation system comprises a refrigerant loop and a supplementary air flow path. The refrigerant loop comprises a compressor (2) and a first heat exchanger (7) in communication with the compressor (2). The supplementary air flow path is used to guide a portion of a refrigerant discharged from the compressor (2) to an air intake opening of the compressor (2). The supplementary air flow path comprises a first flow path (10) and a second flow path (15). The air intake opening of the compressor (2) can be selectively in communication with one or both of the first flow path (10) and the second flow path (15).

Description

Refrigerant circulation system and control method thereof and air conditioner

This disclosure is based on the application with the CN application number CN201910111069.4 and the filing date of February 12, 2019, and claims its priority. The disclosure of the CN application is hereby incorporated into this disclosure as a whole.

Technical field

The present disclosure relates to the technical field of refrigeration, and in particular to a refrigerant circulation system for reducing compressor surge, a control method thereof, and an air conditioner.

Background technique

Most of the large-scale commercial air conditioners in related technologies use centrifugal compressors. Because of their large cooling capacity, reliable work and long operating life, they are popular among consumers in the market, but they also have many defects, which greatly affect The scope of its application.

Surge is an inherent aerodynamic phenomenon of centrifugal compressors, and surge will increase the operating noise, vibration and power consumption of the compressor, and in severe cases, it will damage the internal blades of the compressor or even cause the entire compressor to be damaged. And when the system condensing pressure is too high or the cooling load is too low, the surge problem becomes more prominent.

Summary of the invention

The present disclosure aims to provide a refrigerant circulation system, an air conditioner, and a control method of the refrigerant circulation system, so as to improve the problem that the compressor is prone to surge in the related art.

According to one aspect of the embodiments of the present disclosure, the present disclosure provides a refrigerant circulation system, and the refrigerant circulation system includes:

The refrigerant circuit includes a compressor and a first heat exchanger connected to the compressor; and

The make-up flow path is used to guide part of the refrigerant discharged from the compressor to the suction port of the compressor.

In some embodiments, the amount of refrigerant guided to the suction port of the compressor by the supplemental flow path is adjustable.

In some embodiments, the supplemental flow path includes:

The first flow path includes an inlet port communicating with the first position of the refrigerant circuit and an outlet port communicating with the suction port of the compressor; and

The second flow path includes an inlet end communicating with a second position where the pressure of the refrigerant circuit is lower than the first position and an outlet end communicating with the suction port of the compressor.

Wherein, the suction port of the compressor may be selectively connected to one of the first flow path and the second flow path, and/or the suction port of the compressor may be selectively connected to both the first flow path and the second flow path.

In some embodiments, the first heat exchanger is used to condense the refrigerant therein, and the inlet end of the first flow path communicates with the flow path between the first heat exchanger and the exhaust port of the compressor.

In some embodiments, the refrigerant circulation system further includes a reversing valve. The reversing valve includes an inlet communicating with the exhaust port of the compressor, an outlet communicating with the suction port of the compressor, and a first heat exchanger communicating with the first heat exchanger. A working port and a second working port for connecting the second heat exchanger, and the inlet end of the first flow path communicates with the flow path between the exhaust port of the compressor and the inlet of the reversing valve.

In some embodiments, the refrigerant circulation system further includes a subcooler in communication with the first heat exchanger, and the subcooler includes:

The first inlet is used to introduce the refrigerant to be supercooled;

The first outlet is used to output the subcooled refrigerant;

The second outlet is in communication with the second flow path, and is used to deliver the refrigerant after cooling the refrigerant to be supercooled to the suction port of the compressor.

In some embodiments, the supercooler further includes a second inlet for introducing refrigerant for cooling the refrigerant to be supercooled.

In some embodiments, the refrigerant circulation system further includes:

The first valve is located in the first flow path;

The second valve is located in the second flow path;

The detection component includes a flow detection component used to detect the flow rate M of the suction port of the compressor or a speed detection component used to detect the rotation speed P of the compressor;

The controller is in communication connection with the first valve, the second valve and the flow detection component. The controller is used to close the first valve and the second valve when M>B or P>P2, and when B>M>A or P2> When P>P1, one of the first valve and the second valve is controlled to open, and when M<A or P<P1, both the first valve and the second valve are controlled to open.

In some embodiments, the refrigerant circulation system further includes:

The first valve is located in the first flow path;

The second valve is located in the second flow path;

The controller is in communication with the first valve, the second valve and the detection component. The controller is used to close the first valve and the second valve when M>B or P>P2, and when A<M<B or P1<P When <P2, open the second valve and close the first valve, when M<A or P<P1, open the first valve and close the second valve or open the first valve and the second valve.

In some embodiments, the refrigerant circulation system further includes a third heat exchanger, which is arranged in the first flow path, and the third heat exchanger is used for cooling the refrigerant flowing therethrough.

In some embodiments, the refrigerant circulation system further includes a fan for passing air through the first heat exchanger and the third heat exchanger.

In some embodiments, the compressor is a centrifugal compressor.

According to another aspect of the present application, there is also provided an air conditioner including the above-mentioned refrigerant circulation system.

According to another aspect of the present application, there is also provided a control method of the above-mentioned refrigerant circulation system, and the control method includes:

Obtain the flow information of the suction port M of the compressor or the information of the rotational speed P of the compressor; and

When M<B or P<P2, lead part of the refrigerant discharged from the compressor to the suction port of the compressor.

In some embodiments,

When A<M<B or P1<P<P2, lead part of the refrigerant in the first position in the refrigerant circuit to the suction port of the compressor;

When M<A or P<P1, the part of the refrigerant in the first position and the part of the refrigerant in the second position whose pressure is different from the first position are led to the compressor suction port.

In some embodiments,

When M<A or P<P1, lead part of the refrigerant in the first position in the refrigerant circuit to the suction port of the compressor, or the first position in the refrigerant circuit and the second position where the pressure is lower than the first position Part of the refrigerant is led to the suction port of the compressor;

When A<M<B or P1<P<P2, only part of the refrigerant in the second position is led to the suction port of the compressor.

In some embodiments,

The first position is between the suction port of the compressor and the first heat exchanger for condensing the refrigerant discharged from the compressor; or

The second position is the exhaust port of the subcooler for subcooling the condensed refrigerant.

By applying the technical solution of the present application, the problem that the compressor is prone to surge is improved by supplying air to the suction port of the compressor.

Description of the drawings

The drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The schematic embodiments and descriptions of the present disclosure are used to explain the present disclosure, and do not constitute an improper limitation of the present disclosure. In the attached picture:

Fig. 1 shows a schematic diagram of a refrigerant circulation system of an embodiment of the present disclosure; and

FIG. 2 shows a control flowchart of the refrigerant circulation system of the embodiment of the present disclosure. .

detailed description

In order to make the objectives, technical solutions, and advantages of the present disclosure clearer, the following further describes the present disclosure in detail with reference to the embodiments and the drawings. Here, the exemplary embodiments and descriptions of the present disclosure are used to explain the present disclosure, but are not intended to limit the present disclosure.

Fig. 1 shows the principle diagram of the refrigerant circulation system of this embodiment. As shown in Fig. 1, the refrigerant circulation system of this embodiment includes a refrigerant circuit, and the refrigerant circuit includes a compressor 2 and a first heat exchange communicating with the compressor 2器7.

The refrigerant circuit also includes a first pipe 20 for connecting the first heat exchanger 7 and the second heat exchanger, and a first throttling component 9 provided between the first heat exchanger 7 and the second heat exchanger.

Optionally, the first heat exchanger 7 is used as a condenser, and the second heat exchanger is used as an evaporator. The refrigerant compressed by the compressor 2 enters the first heat exchanger 7 to be condensed. After the condensation, the refrigerant enters the second heat exchanger after being throttled and depressurized by the first throttling component 9, where the refrigerant enters the second heat exchanger. The internal evaporation absorbs heat, and the refrigerant evaporated in the second heat exchanger returns to the suction port of the compressor 2.

The refrigerant circulation system further includes a reversing valve 5. The reversing valve 5 includes an inlet communicating with the exhaust port of the compressor 2, an outlet communicating with the suction port of the compressor 2, and a first heat exchanger 7 communicating with the first heat exchanger. The working port and the second working port for connecting the second heat exchanger, the inlet end of the first flow path 10 is in communication with the flow path between the exhaust port of the compressor 2 and the inlet of the reversing valve 5.

The reversing valve 5 has a first state and a second state. In the first state, the inlet of the reversing valve 5 is connected to the first working port, and the second working port is connected to the outlet; in the second state, the reversing valve 5 The inlet of the reversing valve is connected to the second working port, and the first working port of the reversing valve 5 is connected to the outlet.

As shown in FIG. 1, the refrigerant circulation system further includes a second pipeline 21 for communicating the second heat exchanger with the second working port of the reversing valve 5.

When the reversing valve 5 is in the first state, the refrigerant compressed by the compressor 2 enters the first heat exchanger 7 through the inlet and the first working port of the reversing valve 5 for condensation, and the refrigerant passes through the first throttling part after condensation. After 9 throttling and depressurization, it enters the second heat exchanger. The refrigerant evaporates and absorbs heat in the second heat exchanger. The refrigerant evaporated in the second heat exchanger passes through the second working port and outlet of the reversing valve 5. Go back to the suction port of compressor 2.

When the reversing valve 5 is in the second state, the refrigerant compressed by the compressor 2 enters the second heat exchanger through the inlet and the second working port of the reversing valve 5 for condensation, and the refrigerant passes through the first throttling component 9 after condensation. After throttling and depressurization, it enters the first heat exchanger 7, the refrigerant evaporates in the first heat exchanger 7 and absorbs heat, and the refrigerant evaporated in the second heat exchanger 7 passes through the first working port of the reversing valve 5 and The outlet returns to the suction port of the compressor 2.

The refrigerant circulation system further includes a subcooler 17 connected to the flow path between the first heat exchanger 7 and the second heat exchanger.

The subcooler 17 includes a first inlet for introducing the refrigerant to be supercooled, a first outlet for outputting the supercooled refrigerant, and a second outlet for outputting the refrigerant cooled down as the refrigerant to be supercooled.

The first inlet of the subcooler 17 communicates with the first heat exchanger through the third pipeline 16, and the first outlet of the multicooler 17 communicates with the first pipeline 20, which is used for communication

In some embodiments, the subcooler 17 includes a tank-shaped component, and the refrigerant entering the tank-shaped component from the first inlet is partially evaporated due to a pressure drop, and the evaporated refrigerant is a liquid refrigerant that is cooled and supercooled. The first outlet is arranged at the bottom of the tank component and is used to output the supercooled liquid refrigerant. The second outlet is arranged at the upper part of the canned part, and is used to output the gaseous refrigerant after cooling the refrigerant to be supercooled.

In this embodiment, the supercooler 17 further includes a second inlet for introducing refrigerant for cooling the refrigerant to be supercooled. The refrigerant circulation system also includes a fourth pipeline 18. The inlet end of the fourth pipeline 18 is in communication with the first pipeline 20 or the third pipeline 16, and the outlet end of the fourth pipeline 18 is connected to the second subcooler 17 The inlet is connected. A second throttle member 19 is provided in the fourth pipeline 18.

The subcooler 17 also includes a first heat exchange part connected between the first inlet and the first outlet and a second heat exchange part connected between the second inlet and the second outlet. The flowing refrigerant evaporates in the second heat exchange part to cool down the refrigerant in the first heat exchange part, so that the refrigerant in the first heat exchange part is supercooled.

The refrigerant circulation system also includes an oil separator 3 and a check valve 4 connected between the exhaust port of the compressor 2 and the inlet of the reversing valve 5.

The refrigerant circulation system also includes a gas-liquid separator 22 connected between the suction port of the compressor 2 and the outlet of the reversing valve 5. The gas outlet of the gas-liquid separator 22 is connected with the suction port of the compressor 2 to prevent The liquid refrigerant enters the compressor 2.

The compressor of the refrigerant circulation system of this embodiment is a centrifugal compressor. In order to improve the surge problem of the centrifugal compressor, the refrigerant circulation system of this embodiment also includes a make-up air flow path, which is used to compress the compressor 2 Part of the refrigerant is delivered to the suction port of the compressor 2 to increase the suction pressure of the compressor 2 and improve the problem of the centrifugal compressor prone to surge.

In this embodiment, the amount of refrigerant guided to the suction port of the compressor 2 by the supplemental flow path is adjustable.

Specifically, the supplemental flow path includes a first flow path 10 and a second flow path 15. The first flow path 10 includes an inlet end communicating with the first position of the refrigerant circuit and an outlet end for communicating with the suction port of the compressor 2; The second flow path 15 includes an inlet end communicating with a second position where the pressure of the refrigerant circuit is lower than the first position, and an outlet end communicating with the suction port of the compressor 2.

In order to change the pressure of the refrigerant delivered to the suction port of the compressor 2 by the make-up flow, the suction port of the compressor 2 may be connected to one of the first flow path 10 and the second flow path 15, and/or the suction port of the compressor 2 The air port can optionally be connected to both the first flow path 10 and the second flow path 15.

Optionally, the inlet end of the first flow path 10 communicates with the flow path between the first heat exchanger 7 serving as a condenser and the exhaust port of the compressor 3 to compress the high-temperature and high-pressure refrigerant compressed by the compressor 2 Lead to the suction port of the compressor 2.

As shown in Figure 1, the inlet end of the first flow path 10 communicates with the flow path between the inlet of the reversing valve 5 and the exhaust port of the compressor 2 to guide the high-temperature and high-pressure refrigerant compressed by the compressor 2 to the compression The suction port of machine 2.

Optionally, a third heat exchanger 6 is further provided in the first flow path 10, and the third heat exchanger 6 is used for cooling the refrigerant flowing therethrough, so as to reduce the suction of the first flow path 10 to the compressor 2. The temperature of the refrigerant conveyed by the port and the specific volume of the refrigerant are increased to increase the suction volume of the compressor 2, which is beneficial to improve the surge problem of the compressor 2. The third heat exchanger 6 and the first heat exchanger 7 share a fan 8.

A first valve 12 is provided in the first flow path 10. Optionally, a third throttling component 11 is further provided in the first flow path 10.

The inlet end of the second flow path 15 is in communication with the second outlet of the subcooler 17, and the outlet end of the second flow path 15 is used to deliver refrigerant to the suction port of the compressor 2. The refrigerant output from the second outlet of the subcooler 17 has a low temperature and a large specific volume, so the suction volume of the suction port of the compressor 2 can be increased, which is beneficial to improve the surge problem of the compressor 2.

A second valve 14 is provided in the second flow path 15, and optionally, a fourth throttle member 13 is further provided in the second flow path 15.

In some embodiments, the outlet end of the first flow path 10 and/or the second flow path 15 is in communication with the inlet of the gas-liquid separator 22, and the gas outlet of the gas-liquid separator 22 is in communication with the suction port of the compressor 2 to Prevent the liquid refrigerant from entering the compressor 2 and causing liquid shock.

The refrigerant circulation system further includes a detection component, and the detection component is a flow detection component 1 for detecting the flow rate M of the suction port of the compressor 2 or a speed detection component for detecting the rotation speed P of the compressor 2.

The refrigerant circulation system also includes a controller, which is in communication connection with the first valve 12, the second valve 14 and the detection component. The controller is used to close the first valve 12 and the second valve 14 when M>B or P>P2 , When A<M<B or P1<P<P2, open the second valve 14 and close the first valve 11, when M<A or P<P1, open the first valve 12 and close the second valve 14 or open the first Valve 12 and second valve 14.

It can be seen that when A<M<B or P1<P<P2, part of the refrigerant in the first position in the refrigerant circuit is guided to the suction port of the compressor 2 through the first flow path 10;

When M<A or P<P1, part of the refrigerant at the first position and the part of the refrigerant at the second position whose pressure is different from the first position are guided to the suction port of the compressor 2 through the first flow path 10 and the second flow path 15 respectively. .

In some embodiments, the controller is used to: close the first valve 12 and the second valve 14 when M>B or P>P2, and open and close the second valve 14 when A<M<B or P1<P<P2 The first valve 11 opens the first valve 12 and closes the second valve 14 or opens the first valve 12 and the second valve 14 when M<A or P<P1.

It can be seen that when A<M<B or P1<P<P2, only part of the refrigerant in the second position is guided to the suction port of the compressor 2 through the second flow path 15.

When M<A or P<P1, part of the refrigerant at the first position in the refrigerant circuit is guided to the suction port of the compressor 2 through the first flow path 10, or the first flow path 10 and the second flow path 15 respectively Part of the refrigerant in the first position and the second position whose pressure is lower than the first position in the refrigerant circuit is led to the suction port of the compressor.

According to another aspect of the present application, there is also provided a control method of a refrigerant circulation system. The control method includes obtaining flow rate information of the suction port M of the compressor 2 or information of the rotational speed P of the compressor 2; and when M<B Or when P<P2, lead part of the refrigerant discharged from the compressor 2 to the suction port of the compressor 2.

In this embodiment, when A<M<B or P1<P<P2, lead part of the refrigerant in the first position in the refrigerant circuit to the suction port of compressor 2; when M<A or P<P1, The part of the refrigerant at the first position and the part of the refrigerant at the second position whose pressure is different from the first position is led to the suction port of the compressor 2.

In some embodiments, when M<A or P<P1, part of the refrigerant at the first position in the refrigerant circuit is directed to the suction port of the compressor 2, or the pressure at the first position in the refrigerant circuit is lower than Part of the refrigerant in the second position in the first position is led to the suction port of the compressor; when A<M<B or P1<P<P2, only part of the refrigerant in the second position is led to the suction port of the compressor 2 .

The first position is between the suction port of the compressor 7 and the first heat exchanger 7 for condensing the refrigerant discharged from the compressor 2; the second position is the discharge of the subcooler 17 for subcooling the condensed refrigerant. Breath.

Figure 2 shows a control flow chart of the refrigerant circulation system of this embodiment,

As shown in Figure 2, the rotation speed of the compressor 2 or the suction port flow of the compressor 2 is monitored during the operation of the refrigerant circulation system. When the flow M is greater than B or the compressor rotation speed is greater than P2, it is determined that the compressor flow can be Overcoming the condensing pressure, there will be no surge phenomenon, and the current operating state can be maintained.

When P1＜compressor speed＜P2 or it is detected that the suction side flow rate M is less than B and greater than A, it is determined that the compressor is in the more prone to surge region 1, and the suction port of the compressor 2 needs to be supplemented with refrigerant, then turn on First valve 12.

When the compressor speed <P1 or it is detected that the suction side flow rate M is less than A, it is determined that the compressor is in the region 2 which is prone to surge and requires more bypass unloading. At this time, the first valve 12 and the second valve 14 are both turn on.

After each detection of the system status, after an interval of t1, the system status detection is performed again.

In this embodiment, the speed zone of the compressor or the flow rate on the suction side of the compressor is used to determine the surge zone to control the switching state and duration of the first flow path 10 and the second flow path 15, so as to avoid surge Vibration phenomenon.

The foregoing descriptions are only preferred embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, the embodiments of the present disclosure may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

A refrigerant circulation system, including:

The refrigerant circuit includes a compressor (2) and a first heat exchanger (7) communicating with the compressor (2); and

The supplemental flow path is used to guide part of the refrigerant discharged from the compressor (2) to the suction port of the compressor (2).
The refrigerant circulation system according to claim 1, characterized in that the amount of refrigerant guided to the suction port of the compressor (2) from the make-up flow path is adjustable.
The refrigerant circulation system according to claim 1, wherein the supplementary air flow path comprises:

The first flow path (10) includes an inlet end communicating with the first position of the refrigerant circuit and an outlet end communicating with the suction port of the compressor (2); and

The second flow path (15) includes an inlet end communicating with a second position where the pressure of the refrigerant circuit is lower than the first position and an outlet end communicating with the suction port of the compressor (2),

Wherein, the suction port of the compressor (2) can be selectively connected to one of the first flow path (10) and the second flow path (15), and/or the suction port of the compressor (2) The air port can optionally communicate with both the first flow path (10) and the second flow path (15).
The refrigerant circulation system according to claim 3, wherein the first heat exchanger (7) is used to condense the refrigerant therein, and the inlet end of the first flow path (10) is connected to the first heat exchanger (7). ) And the flow path between the exhaust port of the compressor (3).
The refrigerant circulation system according to claim 3, further comprising a reversing valve (5), the reversing valve (5) including an inlet communicating with the exhaust port of the compressor (2), and (2) The outlet communicating with the suction port, the first working port communicating with the first heat exchanger (7) and the second working port for connecting the second heat exchanger, the first flow path (10) The inlet end of) communicates with the flow path between the exhaust port of the compressor (2) and the inlet of the reversing valve (5).
The refrigerant circulation system according to claim 3, further comprising a supercooler (17) communicating with the first heat exchanger (7), the supercooler (7) comprising:

The first inlet is used to introduce the refrigerant to be supercooled;

The first outlet is used to output the subcooled refrigerant;

The second outlet is in communication with the second flow path (15), and is used for conveying the refrigerant after cooling the refrigerant to be supercooled to the suction port of the compressor (2).
The refrigerant circulation system according to claim 6, wherein the supercooler (17) further comprises a second inlet for introducing a refrigerant for cooling the refrigerant to be supercooled.
The refrigerant circulation system according to claim 3, further comprising:

The first valve (12) is arranged in the first flow path (10);

The second valve (14) is arranged in the second flow path (15);

The detection component includes a flow detection component used to detect the flow rate M of the suction port of the compressor (2) or a speed detection component used to detect the rotation speed P of the compressor (2);

The controller is in communication connection with the first valve (12), the second valve (14) and the flow detection component (1), and the controller is used to: close when M>B or P>P2 The first valve (12) and the second valve (14) control the first valve (12) and the second valve (14) when B>M>A or P2>P>P1 When M<A or P<P1, both the first valve (12) and the second valve (14) are controlled to open.
The refrigerant circulation system according to claim 3, further comprising:

The first valve (12) is arranged in the first flow path (10);

The second valve (14) is arranged in the second flow path (15);

The detection component includes a flow detection component (1) for detecting the flow rate M of the suction port of the compressor (2) or a speed detection component for detecting the rotation speed P of the compressor (2);

The controller is communicatively connected with the first valve (12), the second valve (14) and the detection component, and the controller is configured to: close the first valve (12), or P>P2. The valve (12) and the second valve (14) open the second valve (14) and close the first valve (11) when A<M<B or P1<P<P2, and when M<B When A or P<P1, the first valve (12) is opened and the second valve (14) is closed or the first valve (12) and the second valve (14) are opened.
The refrigerant circulation system according to claim 3, further comprising a third heat exchanger (6), arranged in the first flow path (10), and the third heat exchanger (6) is used for The refrigerant cools down inside.
The refrigerant circulation system according to claim 10, further comprising a fan (8) for passing air through the first heat exchanger (7) and the third heat exchanger (6).
The refrigerant circulation system according to claim 1, wherein the compressor (2) is a centrifugal compressor.
An air conditioner, characterized by comprising the refrigerant circulation system according to claim 1.
A control method of a refrigerant circulation system according to claim 1, comprising:

Acquiring information on the flow rate M of the suction port of the compressor (2) or information on the rotational speed P of the compressor (2); and

When M<B or P<P2, part of the refrigerant discharged from the compressor (2) is guided to the suction port of the compressor (2).
The control method according to claim 14, wherein:

When A<M<B or P1<P<P2, lead part of the refrigerant at the first position in the refrigerant circuit to the suction port of the compressor (2);

When M<A or P<P1, part of the refrigerant at the first position and part of the refrigerant at the second position whose pressure is different from the first position is led to the compressor (2) suction port.
The control method according to claim 14, wherein:

When M<A or P<P1, lead part of the refrigerant in the first position in the refrigerant circuit to the suction port of the compressor (2), or make the first position and pressure in the refrigerant circuit lower than the first position in the refrigerant circuit. Part of the refrigerant in the second position of the position is guided to the suction port of the compressor;

When A<M<B or P1<P<P2, only part of the refrigerant in the second position is led to the suction port of the compressor (2).
The control method according to claim 15 or 16, wherein:

The first position is located between the suction port of the compressor (7) and the first heat exchanger (7) for condensing the refrigerant discharged from the compressor (2); or

The second position is the exhaust port of the supercooler (17) for supercooling the condensed refrigerant.