WO2018035268A1

WO2018035268A1 - Gas discharge apparatus, refrigerating and air-conditioning unit, and method of discharging non-condensable gas

Info

Publication number: WO2018035268A1
Application number: PCT/US2017/047223
Authority: WO
Inventors: Shenglong Wang; Fang XUE; Xiuping Su
Original assignee: York (Wuxi) Air Conditioning And Refrigeration Co., Ltd.; Johnson Controls Technology Company
Priority date: 2016-08-17
Filing date: 2017-08-16
Publication date: 2018-02-22
Also published as: TW201807367A; CN107763910A

Abstract

The present disclosure provides a gas discharge apparatus, a refrigerating and air-conditioning unit, and a method of discharging a non-condensable gas. The gas discharge apparatus comprises a gas discharge compressor and a heat exchanger, wherein a gas suction port of the gas discharge compressor is connected to a condenser of the refrigerating and air-conditioning unit to introduce a mixed gas comprising a gaseous refrigerant and a non-condensable gas into the gas discharge compressor to be compressed; a gas inlet of the heat exchanger is connected to a gas discharge port of the gas discharge compressor; a liquid outlet of the heat exchanger is connected to an evaporator or the condenser of the refrigerating and air-conditioning unit; the heat exchanger further has a cold source inlet and a cold source outlet available for the cold source to flow through, such that the compressed mixed gas enters the heat exchanger to exchange heat with the cold source and the gaseous refrigerant is condensed into a liquid refrigerant which is discharged into the evaporator or condenser, and a gas outlet is configured to discharge the separated non-condensable gas from the heat exchanger. The gas discharge apparatus according to the present disclosure may effectively separate and discharge the non-condensable gas in the refrigerating and air-conditioning unit, thereby guaranteeing its safe and efficient operation.

Description

GAS DISCHARGE APPARATUS, REFRIGERATING AND

AIR-CONDITIONING UNIT, AND METHOD OF DISCHARGING

NON-CONDENSABLE GAS

FIELD OF THE INVENTION

[0001] The present disclosure generally relates to the field of air-conditioning and refrigeration, and more particularly to a gas discharge apparatus, a refrigerating and air-conditioning unit, and a method of discharging a non-condensable gas.

BACKGROUND OF THE INVENTION

[0002] A traditional refrigerating and air-conditioning unit comprises four major components: a compressor, a condenser, a throttling valve, and an evaporator. For some refrigerating and air-conditioning units using a low-pressure refrigerant (e.g., R123, R1233zd, etc.), some zones with a pressure below the atmospheric pressure will be formed inside the refrigerating and air-conditioning unit system during operation. Due to the existence of the low-pressure zones, air would possibly penetrate into the refrigerating and air-conditioning unit, such that a non-condensable gas will build up in the condenser, causing degradation of the heat-exchanging performance of the condenser and thus decreasing the refrigeration capacity of the refrigerating and air-conditioning unit. Meanwhile, the rise in the condensation pressure and the condensation temperature of the system further leads to an increase in the exhaust gas temperature of the compressor and the power consumption, and a decrease in the energy efficiency of the refrigerating and air-conditioning unit. In addition, an unduly high exhaust gas temperature might cause carbonization of a lubricant in the compressor, which will dampen the lubrication effect, and in worse cases cause the compressor to be stuck or even burn down the compressor motor.

[0003] Therefore, for a refrigerating and air-conditioning system with a low-pressure refrigerant, a set of gas discharge apparatus is additionally required to at least partially solve the problems above.

SUMMARY OF THE INVENTION

[0004] In order to at least partially solve the problems above, the present disclosure provides a gas discharge apparatus for a refrigerating and air-conditioning unit, characterized by comprising: [0005] a gas discharge compressor, a gas suction port of which is connected to a condenser of the refrigerating and air-conditioning unit to introduce, via the condenser, a mixed gas comprising a gaseous refrigerant and a non-condensable gas into the gas discharge compressor for being compressed; and

[0006] a heat exchanger, a gas inlet of which is connected to a gas discharge port of the gas discharge compressor, and a liquid outlet of which is connected to an evaporator or a condenser of the refrigerating and air-conditioning unit, wherein the heat exchanger has a cold source inlet and a cold source outlet available for the cold source to flow through, such that the compressed mixed gas enters the heat exchanger to exchange heat with the cold source to condense the gaseous refrigerant into a liquid refrigerant, and the heat exchanger further comprises a gas outlet from which the non-condensable gas is discharged out of the gas discharge apparatus.

[0007] The gas discharge apparatus further comprises a control valve, wherein the control valve comprises:

[0008] a gas suction control valve disposed between the gas suction port of the gas discharge compressor and the condenser; and

[0009] a gas discharge control valve disposed downstream to the gas outlet of the heat exchanger.

[0010] Optionally, the gas discharge apparatus further comprises a liquid discharge control device disposed between the liquid outlet of the heat exchanger and the evaporator or the condenser to control the discharge of the liquid refrigerant from the liquid outlet of the heat exchanger into the evaporator or the condenser.

[0011] Optionally, the liquid discharge control device is a liquid discharge control valve.

[0012] Optionally, the liquid discharge control device is a throttling orifice.

[0013] Optionally, the gas discharge apparatus comprises a liquid level meter connected to the heat exchanger to sense a liquid level height of the liquid refrigerant within the heat exchanger to control the opening and closing of the liquid discharge control valve.

[0014] Optionally, the gas discharge apparatus comprises a gas discharge pump, wherein a gas suction port of the gas discharge pump is connected to the gas outlet of the heat exchanger to discharge the non-condensable gas in the heat exchanger.

[0015] Optionally, the gas discharge apparatus comprises a drier-filter connected to the liquid outlet of the heat exchanger to dry and filter the liquid refrigerant discharged from the heat exchanger.

[0016] Optionally, the gas discharge compressor is a vortex compressor, a piston compressor, or a rolling-rotor compressor.

[0017] Optionally, the heat exchanger is a recuperative heat exchanger

[0018] Optionally, the cold source is selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, and a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve.

[0019] The present disclosure further provides a refrigerating and air-conditioning unit, comprising:

[0020] an evaporator;

[0021] a first compressor, a gas suction port of which is connected to a gas outlet of the evaporator;

[0022] a condenser, a gas inlet of which is connected to a gas discharge port of the first compressor;

[0023] a throttling valve, an entrance of which is connected to a liquid outlet of the condenser, and an exit of which is connected to a liquid inlet of the evaporator; and

[0024] the gas discharge apparatus as above mentioned.

[0025] The present disclosure further provides a method of discharging a non-condensable gas in a refrigerating and air-conditioning unit, characterized in that the refrigerating and air-conditioning unit is the refrigerating and air-conditioning unit having a gas discharge apparatus as mentioned above, wherein the gas discharging method comprises:

[0026] a compressing process of introducing a mixed gas comprising a gaseous refrigerant and the non-condensable gas by a condenser of the refrigerating and air-conditioning unit into a gas discharge compressor to be compressed to raise a pressure and temperature of the mixed gas;

[0027] a condensing process of allowing the compressed mixed gas to enter the heat exchanger and exchange heat with a cold source, so that the gaseous refrigerant is condensed into a liquid refrigerant; [0028] a liquid discharging process of allowing the liquid refrigerant to be discharged from the heat exchanger into an evaporator or the condenser of the refrigerating and air-conditioning unit; and

[0029] a gas discharging process of discharging the non-condensable gas from the heat exchanger.

[0030] Optionally, the cold source used in the condensing process is selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, and a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve.

[0031] The gas discharge apparatus according to the present disclosure may withdraw the mixed gas comprising a gaseous refrigerant and a non-condensable gas out of the condenser of the refrigerating and air-conditioning unit by utilizing the gas discharge compressor of the gas discharge apparatus to compress the mixed gas to raise its pressure and temperature and increase the condensation temperature of the gaseous refrigerant in the mixed gas, and then by introducing the compressed mixed gas into the heat exchanger of the gas discharge apparatus to exchange heat with the cold source so that the gaseous refrigerant in the mixed gas is condensed into a liquid refrigerant to be separated from the non-condensable gas, followed by discharging the liquid refrigerant into the evaporator or condenser of the refrigerating and air-conditioning unit to re-enter the refrigeration cycle and discharging the non-condensable gas. In this way, a low-pressure state may be maintained inside the refrigerating and air-conditioning unit, which helps to maintain the condensation pressure inside the condenser and thus guarantees the refrigeration capacity and energy efficiency of the refrigerating and air-conditioning unit such that it operates safely and efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings below constituting part of the present disclosure are for an understanding of the present disclosure. In the drawings:

[0033] Fig. 1 is a schematic diagram illustrating a configuration of a traditional refrigerating and air-conditioning unit;

[0034] Fig. 2 is a schematic diagram illustrating a configuration of a first embodiment of a gas discharge apparatus according to the present disclosure;

[0035] Fig. 3 is a schematic diagram illustrating a configuration of a refrigerating and air-conditioning unit having the gas discharge apparatus of Fig. 2;

[0036] Fig. 4 is a schematic diagram illustrating a compressing process of the gas discharge apparatus of the refrigerating and air-conditioning unit of Fig. 3;

[0037] Fig. 5 is a schematic diagram illustrating a condensing process of the gas discharge apparatus of the refrigerating and air-conditioning unit of Fig. 3;

[0038] Fig. 6 is a schematic diagram illustrating a liquid discharging process of the gas discharge apparatus of the refrigerating and air-conditioning unit of Fig. 3;

[0039] Fig. 7 is a schematic diagram illustrating a gas discharging process of the gas discharge apparatus of the refrigerating and air-conditioning unit of Fig. 3;

[0040] Fig. 8 is a schematic diagram illustrating a configuration of a second embodiment of a gas discharge apparatus according to the present disclosure;

[0041] Fig. 9 is a schematic diagram illustrating a liquid discharging process of the gas discharge apparatus of the refrigerating and air-conditioning unit having the gas discharge apparatus of Fig. 8, wherein a liquid outlet of the gas discharge apparatus is connected to an evaporator; and

[0042] Fig. 10 is a schematic diagram illustrating a liquid discharging process of the gas discharge apparatus of the refrigerating and air-conditioning unit having the gas discharge apparatus of Fig. 8, wherein a liquid outlet of the gas discharge apparatus is connected to a condenser.

DETAILED DESCRIPTION OF THE INVENTION

[0043] The description infra provides a large number of specific details for a more thorough understanding of the present disclosure. However, it is apparent to those skilled in the art that the present disclosure may be implemented without one or more of these details. In other examples, in order to avoid obscuring the present disclosure, some technical features well known in the art may not be depicted.

[0044] The present disclosure is mainly applied to a refrigerating and air-conditioning unit having a low-pressure refrigerant (e.g., R123, R1233zd, etc.).

[0045] Particularly, a system configuration of a refrigerating and air-conditioning unit 100, as illustrated in Fig. 1, mainly comprises four major components: an evaporator 110, a first compressor 120, a condenser 130, and a throttling valve 140, which are in fluid communication via a pipeline and form a closed system relative to an external environment. The closed system of the refrigerating and air-conditioning unit 100 is filled with a refrigerant. During a refrigeration process, a liquid refrigerant in the evaporator 110 exchanges heat with chilled water at a water side of the evaporator 110. The liquid refrigerant absorbs the heat in the chilled water and after heat absorption and evaporation turns into a gaseous refrigerant which is discharged from a gas outlet 110b of the evaporator 110; at the same time, the temperature of the chilled water drops. The chilled water with a dropped temperature is discharged out of the evaporator 110 and delivered to an external environment to be cooled to cool the external environment by absorbing heat, thereby achieving the objective of refrigeration. The chilled water with a raised temperature after exchanging heat with the external environment is delivered back to the evaporator 110 to be chilled again, and the cycle repeats. The gaseous refrigerant is discharged from a gas outlet 110b of the evaporator 110, and then enters the first compressor 120 through a tube 151 via a gas suction port 120a. The first compressor 120 acts to compress the gaseous refrigerant to raise its temperature and pressure and then discharges it via a discharge port 120b. The compressed gaseous refrigerant enters the condenser 130 via a gas inlet 130a through a tube 152 and exchanges heat with cooling water at a water side of the condenser 130. The cooling water absorbs the heat of the compressed gaseous refrigerant and re-condenses the gaseous refrigerant into a liquid refrigerant. The liquid refrigerant flows out of the condenser 130 via the liquid outlet 130b, through a tube 153, and at the throttling valve 140 turns into a gas-liquid dual phase by throttling to reduce its pressure, and then through a tube 154 enters the evaporator 110 again via the liquid inlet 110a, thereby completing a refrigeration cycle.

[0046] As illustrated in Fig. 2, a gas discharge apparatus 200 according to a first embodiment of the present disclosure comprises: a heat exchanger 210, a gas discharge compressor 220, a gas suction control valve 231, a liquid discharge control valve 232, a gas discharge control valve 233, a liquid level meter 240, a drier-filter 250, and a gas discharge pump 260, etc., which are in fluid connection with each other via a pipeline.

[0047] In the present disclosure, the heat exchanger 210 may be a recuperative heat exchanger, such as a shell-and-tube heat exchanger, a plate heat exchanger, a copper-tube aluminum-fin heat exchanger, a coil heat exchanger, etc., and the gas discharge compressor 220 may be selected from a vortex compressor, a piston type compressor, or a rolling-rotor compressor, etc., depending on a desired gas discharging efficiency. The present disclosure has no specific limitations thereto. [0048] In the present disclosure, the cold source supplied to the heat exchanger may be selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, and a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve, etc., depending on a desired separation efficiency. The present disclosure has no specific limitations thereto.

[0049] Fig. 3 shows a manner of connecting the gas discharge apparatus 200 according to the first embodiment of the present invention to a refrigerating and air-conditioning unit. The gas discharge apparatus 200 is fluidly connected to the condenser 130 of the refrigerating and air-conditioning unit 100 via a tube 251. The mixed gas comprising a gaseous refrigerant and a non-condensable gas in the condenser 130 is introduced into the gas discharge apparatus 200. Meanwhile, the gas discharge apparatus 200 is fluidly connected to the evaporator 110 of the refrigerating and air-conditioning unit 100 via a tube 254, to discharge the liquid refrigerant obtained from the condensation of the mixed gas into the evaporator 110, such that the liquid refrigerant re-enters the refrigeration cycle. The gas discharge pump 260 of the gas discharge apparatus 200 is in communication with the outside to discharge the non-condensable gas separated from the mixed gas out of the gas discharge apparatus 200. It needs to be noted that the gas discharge apparatus discharges the liquid refrigerant obtained from condensing and separating the mixed gas into the evaporator or the condenser. In the embodiment of Fig. 3, the liquid refrigerant is discharged into the evaporator.

[0050] The non-condensable gas is separated and condensed in four phases: a compressing process, a condensing process, a liquid discharging process, and a gas discharging process, which will be explained hereinafter with reference to Figs. 4-7.

[0051] 1. In the compressing process, as illustrated in Fig. 4, firstly, a gas suction control valve 231 disposed on the tube 251 is opened, during which the mixed gas comprising the non-condensable gas and the gaseous refrigerant in the condenser 130 is introduced through the gas suction control valve 231 into a gas discharge compressor 220 via a gas suction port 220a. The gas discharge compressor 220 is started to compress the mixed gas comprising the non-condensable gas and the gaseous refrigerant to raise its pressure and temperature. As the pressure increases, the condensation temperature of the gaseous refrigerant in the compressed mixed gas will also rise, which helps to condense the gaseous refrigerant in the mixed gas into a liquid refrigerant and facilitates separation of the non-condensable gas in the subsequent step. At this point, the liquid discharge control valve 232 and the gas discharge control valve 233 may be opened or closed depending on liquid-discharging and gas -discharging needs of the gas discharge apparatus 200.

[0052] 2. In the condensing process, as illustrated in Fig. 5, the mixed gas comprising the gaseous refrigerant and non-condensable gas compressed in the compressing process to raise its pressure, is discharged out of the gas discharge port 220b of the gas discharge compressor 220 and enters the heat exchanger 210 through the tube 253 via the gas inlet 210a to exchange heat with the cold source. As the mixed gas has a higher pressure at this time, and the condensation temperature of the gaseous refrigerant in the compressed mixed gas is also high, consequently it may be ensured that the gaseous refrigerant in the mixed gas in the heat exchanger 210, after heat exchanging, will all be condensed into a liquid refrigerant, such that the non-condensable gas in the mixed gas may be separated from the refrigerant through the phase change of the refrigerant. The separated liquid refrigerant and non-condensable gas are stored in different parts of the heat exchanger 210, respectively. At this point, the gas suction control valve 231, the liquid discharge control valve 232, and the gas discharge control valve 233 may be opened or closed depending on the needs of the gas discharge apparatus 200.

[0053] 3. In the liquid-discharging process, as illustrated in Fig. 6, the condensed liquid refrigerant is stored in the heat exchanger 210, and when a liquid level of the liquid refrigerant in the heat exchanger 210 reaches a predetermined height, the liquid level meter 240 senses the liquid level of the liquid refrigerant, and at this point the liquid discharge control valve

232 disposed on the tube 254 is opened so that the liquid refrigerant in the heat exchanger 210 is partially or completely discharged via the liquid outlet 210b into the drier-filter 250, and thereafter into the evaporator 110 to re-enter the refrigeration cycle. It may be understood that the liquid level meter 240 may be configured to sense a liquid-level height of the liquid refrigerant and provide a signal to a control system of the refrigerating and air-conditioning unit 100, such that the control system automatically controls the opening and closing of the liquid discharge control valve 232. The liquid level meter 240 may also be configured to sense the liquid level height of the liquid refrigerant and emit an alarm signal when the liquid level of the liquid refrigerant reaches a predetermined height to manually control the opening and closing of the liquid discharge control valve 232. The present disclosure has no limitation thereto. At this point, the gas suction control valve 231 and the gas discharge control valve

233 may be opened or closed depending on the needs of the gas discharge apparatus 200.

[0054] 4. In the discharging process, as illustrated in Fig. 7, the mixed gas comprising the gaseous refrigerant and the non-condensable gas which has been compressed by the gas discharge compressor 220, exchanges heat with the cold source within the heat exchanger 210, and the gaseous refrigerant is transformed to a liquid refrigerant, while the non-condensable gas has no phase change to enable the two to be separated. The non-condensable gas is stored in the heat exchanger 210. With increase of the separated non-condensable gas, the pressure will increase gradually. When the pressure increases to a predetermined value, the gas discharge control valve 233 on the tube 257 will be opened (optionally, starting the gas discharge pump 260), and at this point, the non-condensable gas in the heat exchanger 210 may be discharged out of the gas discharge apparatus 200 from the gas outlet 210c via the tube 257 (and the gas discharge pump 260), i.e., outside of the refrigerating and air-conditioning unit 100 system. Here, the gas discharge pump 260 is provided to facilitate the discharge of the non-condensable gas. At this point, the gas suction control valve 231 and the liquid discharge control valve 232 may be opened or closed depending on the needs of the gas discharge apparatus 200.

[0055] Fig. 8 illustrates a gas discharge apparatus 300 according to a second embodiment of the present disclosure, comprising a heat exchanger 310, a gas discharge compressor 320, a gas suction control valve 331, a throttling orifice 380, a gas discharge control valve 333, a drier-filter 350, and a gas discharge pump 360, etc., which are in fluid connection with each other via a pipeline. The difference lies in that the gas discharge apparatus 200 according to the first embodiment includes a liquid level meter 240 and a liquid discharge control valve 232 as the liquid discharge control device, while the gas discharge apparatus 300 according to the second embodiment uses a throttling orifice 380 as the liquid discharge control device.

[0056] It needs to be noted that except a different liquid discharging process, the working process of the gas discharge apparatus 300 according to the second embodiment has the same gas suction process, compressing process, and gas discharging process as the working process of the gas discharge apparatus 200 according to the first embodiment. For the conciseness of description, only their difference will be explained here, while the identical parts will not be detailed.

[0057] Fig. 9 is a schematic diagram illustrating a connection between the gas discharge apparatus 300 according to the second embodiment of the present disclosure and the refrigerating and air-conditioning unit 100. The gas discharge apparatus 300 introduces a mixed gas comprising a non-condensable gas and a gaseous refrigerant from the condenser 130 of the refrigerating and air conditioning unit 100. The mixed gas, after being compressed and condensed, is transformed into a liquid refrigerant and a non-condensable gas, which are separated from each other; afterwards, the non-condensable gas is discharged by the gas discharge apparatus 300. Different from the liquid discharging process of the gas discharge apparatus 200, the gaseous refrigerant is condensed into a liquid refrigerant within the gas discharge apparatus 300 which is then discharged via a liquid outlet 310b, throttled to reduce its pressure via the throttling orifice 380, enters the drier-filter 350 to be dried and filtered, and finally is discharged into the evaporator 110 to re-enter the refrigeration cycle; i.e., during the liquid discharging process of the gas discharge apparatus 300, the discharge of the liquid refrigerant is controlled by the throttling orifice 380.

[0058] Fig. 10 is a schematic diagram illustrating another manner of connection between the gas discharge apparatus 300 according to the second embodiment of the present disclosure and the refrigerating and air conditioning unit 100. Similar to the connection manner shown in Fig. 9, the gas discharge apparatus 300 introduces a mixed gas comprising a non-condensable gas and a gaseous refrigerant from the condenser 130 of the refrigerating and air conditioning unit 100. After being compressed and condensed, the mixed gas is transformed into a liquid refrigerant and a non-condensable gas which are separated from each other, and afterwards, the non-condensable gas is discharged from the gas discharge apparatus 300. The difference lies in that in the connection manner shown in Fig. 10, the liquid outlet 310b of the heat exchanger 310 is connected to the condenser 130 of the refrigerating and air-conditioning unit 100; i.e., the gaseous refrigerant is condensed into the liquid refrigerant in the gas discharge apparatus 300, which is then discharged via the liquid outlet 310b, throttled to reduce pressure via the throttling orifice 380, enters into the drier-filter 350 to be dried and filtered, and finally is discharged into the condenser 130 to re-enter the refrigeration cycle.

[0059] It needs to be noted that in the present embodiment, the throttling orifice may also be replaced by a finer tube, which may also play a role of throttling the liquid refrigerant discharged by the heat exchanger.

[0060] As such, the present disclosure also provides a method of discharging a non-condensable gas in a refrigerating and air-conditioning unit, wherein the refrigerating and air-conditioning unit needs to be provided with the gas discharge apparatus as mentioned above. The principle of the gas discharging method is to raise the condensation temperature of the gaseous refrigerant by further compressing the mixed gas comprising a non-condensable gas and a gaseous refrigerant from a condenser, and then to condense the mixed gas by the heat exchanger such that the gaseous refrigerant is converted into a liquid refrigerant; i.e., the mixed gas is separated and purified by using a difference in the condensation temperature between different gas components in the mixed gas, to enable the separation and discharge of the non-condensable gas. The gas discharging method comprises four stages: a compressing process, a condensing process, a liquid discharging process, and a gas discharging process, which will be discussed in detail below.

[0061] 1. In the compressing process, the gas discharge apparatus introduces a mixed gas comprising a gaseous refrigerant and a non-condensable gas from the condenser into a gas discharge compressor of the gas discharge apparatus to be compressed to raise the pressure and temperature of the mixed gas. In this way, the condensation temperature of the gaseous refrigerant in the mixed gas may rise, which facilitates subsequent operations.

[0062] 2. In the condensing process, the compressed mixed gas is discharged into the heat exchanger by the gas discharge compressor to exchange heat with a cold source, during which the gaseous refrigerant is condensed into a liquid refrigerant. After the compression, the condensation temperature of the gaseous refrigerant in the mixed gas rises, which consequently may guarantee that during the condensation process, the gaseous refrigerant in the mixed gas may all be condensed into the liquid refrigerant as much as possible, to enable the separation of the refrigerant from the non-condensable gas through the phase change of the refrigerant. The cold source used in this process may be selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve. The selection may be dependent on the requirements of separation efficiency, and the present disclosure has no limitation thereto.

[0063] 3. In the liquid discharging process, during the condensing process, the liquid refrigerant obtained from condensing the gaseous refrigerant in the mixed gas is finally discharged from the heat exchanger into an evaporator or condenser, and re-enters the refrigeration cycle.

[0064] 4. In the gas discharging process, during the condensing process, the gaseous refrigerant in the mixed gas is condensed into a liquid refrigerant, such that the non-condensable gas is separated and discharged out of the heat exchanger, and eventually out of the refrigerating and air-conditioning unit.

[0065] The present disclosure has been described through the embodiments above. However, it should be understood that the embodiments are only for exemplary and illustrative purposes, and not intended to limit the present disclosure within the scope of the described embodiments above. Besides, those skilled in the art may understand that more alterations and modifications may be made according to the teachings of the present disclosure, and all of these alterations and modifications fall within the protection scope claimed by the present disclosure, which is defined by the appended claims and equivalents thereof.

Claims

CLAIMS I/We Claim:

1. A gas discharge apparatus for a refrigerating and air-conditioning unit, comprising: a gas discharge compressor, a gas suction port of which is connected to a condenser of the refrigerating and air-conditioning unit to introduce, via the condenser, a mixed gas comprising a gaseous refrigerant and a non-condensable gas into the gas discharge compressor to be compressed; and

a heat exchanger, a gas inlet of which is connected to a gas discharge port of the gas discharge compressor, and a liquid outlet of which is connected to an evaporator or a condenser of the refrigerating and air-conditioning unit, wherein the heat exchanger has a cold source inlet and a cold source outlet available for the cold source to flow through, such that the compressed mixed gas enters the heat exchanger to exchange heat with the cold source to condense the gaseous refrigerant into a liquid refrigerant, and the heat exchanger further comprises a gas outlet from which the non-condensable gas is discharged out of the gas discharge apparatus.

2. The gas discharge apparatus according to claim 1, further comprising a control valve which comprises:

a gas suction control valve disposed between the gas suction port of the gas discharge compressor and the condenser; and

a gas discharge control valve disposed downstream to the gas outlet of the heat exchanger.

3. The gas discharge apparatus according to claim 1, further comprising a liquid discharge control device disposed between the liquid outlet of the heat exchanger and the evaporator or the condenser to control the discharge of the liquid refrigerant from the liquid outlet of the heat exchanger into the evaporator or the condenser.

4. The gas discharge apparatus according to claim 3, wherein the liquid discharge control device is a liquid discharge control valve.

5. The gas discharge apparatus according to claim 3, wherein the liquid discharge control device is a throttling orifice.

6. The gas discharge apparatus according to claim 4, wherein the gas discharge apparatus comprises a liquid level meter connected to the heat exchanger to sense a liquid level height of the liquid refrigerant within the heat exchanger to control the opening and closing of the liquid discharge control valve.

7. The gas discharge apparatus according to claim 1, wherein the gas discharge apparatus comprises a gas discharge pump, and a gas suction port of the gas discharge pump is connected to the gas outlet of the heat exchanger to discharge the non-condensable gas in the heat exchanger.

8. The gas discharge apparatus according to claim 1, further comprising a drier-filter, wherein the drier-filter is connected to the liquid outlet of the heat exchanger to dry and filter the liquid refrigerant discharged from the heat exchanger.

9. The gas discharge apparatus according to claim 1, wherein the gas discharge compressor is a vortex compressor, a piston compressor, or a rolling-rotor compressor.

10. The gas discharge apparatus according to claim 1 , wherein the heat exchanger is a recuperative heat exchanger

11. The gas discharge apparatus according to claim 1, wherein the cold source is selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, and a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve.

12. A refrigerating and air-conditioning unit, comprising:

an evaporator;

a first compressor, a gas suction port of which is connected to a gas outlet of the evaporator;

a condenser, a gas inlet of which is connected to a gas discharge port of the first compressor; a throttling valve, an entrance of which is connected to a liquid outlet of the condenser, and an exit of which is connected to a liquid inlet of the evaporator; and

the gas discharge apparatus according to any of claims 1 -11.

13. A method of discharging a non-condensable gas in a refrigerating and air-conditioning unit, comprising:

a compressing process, in which a mixed gas comprising a gaseous refrigerant and a non-condensable gas is introduced by a condenser of the refrigerating and air-conditioning unit into a gas discharge compressor to be compressed to raise a pressure and temperature of the mixed gas;

a condensing process, in which the compressed mixed gas enters the heat exchanger to exchange heat with a cold source, and the gaseous refrigerant is condensed into a liquid refrigerant;

a liquid discharging process, in which the liquid refrigerant is discharged from the heat exchanger into an evaporator or the condenser of the refrigerating and air-conditioning unit; and

a gas discharging process, in which the non-condensable gas is discharged from the heat exchanger.

14. The discharging method according to claim 13, wherein the cold source used in the condensing process is selected from air, other independent water sources, chilled water or cooling water of the refrigerating and air-conditioning unit, and a liquid refrigerant in front of the throttling valve of the refrigerating and air-conditioning unit, or a two-phase refrigerant rear to the throttling valve.