Air conditioning system and its control method

Abstract

The present invention relates to an air conditioning system and a control method thereof. The air conditioning system has an ejector cycle and includes a compressor, a condenser, and an evaporator that are connected in series to form a loop. The ejector cycle includes an ejector. Among them, the ejector obtains a high-pressure liquid flow from the condenser and obtains a low-pressure steam flow or a low-pressure two-phase flow from the evaporator. The high-pressure liquid flow and the low-pressure steam flow or the low-pressure two-phase flow are mixed into a medium-pressure two-phase flow in the ejector and are delivered to a gas-liquid separator. Among them, the gas-phase flow separated by the gas-liquid separator is delivered to the bearing of the compressor to lubricate the bearing.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioners; specifically, the present invention relates to an air conditioning system with an ejector cycle, and further relates to a control method for the air conditioning system. Background Art

[0002] An air conditioning system is a system for routinely conditioning air and improving air quality, and lubricating oil is usually used as a lubricating medium for the bearings of the compressors therein.

[0003] Compared with a compressor using lubricating oil as a lubricating medium, an oil-free compressor can eliminate the entire oil circuit system, save space and cost. In this case, as an oil-free solution, the bearings of the oil-free compressor have the advantages of an oil-free lubrication system and low maintenance costs. In addition, gas has a lower viscosity than lubricating oil, is heat-resistant, and is pollution-free; at the same time, using such bearings is cheaper and has a simpler control logic than using a magnetic levitation bearing solution. The lubricating medium of such bearings can be achieved by bleeding air from the first stage or the second stage of the compressor, which often requires modifying the compressor design; in addition, bleeding air from the compressor also has the potential risk of affecting the performance of the compressor.

[0004] Figure 1 An air conditioning system with an ejector cycle is shown. In the illustrated ejector cycle, the ejector 1 obtains a high-pressure liquid flow as the working flow from the condenser 2 and a low-pressure steam flow or a low-pressure two-phase flow as the entrainment flow from the evaporator 3. These two flows are mixed in the ejector 1 and output in the form of a medium-pressure two-phase flow. After being processed by the gas-liquid separator 4, the obtained liquid-phase flow returns to the evaporator 3, while the obtained gas-phase flow is delivered to the compressor 5 and used as a refrigerant to directly participate in the refrigeration cycle. In Figure 1 In such a system, the provision of the ejector cycle makes the input of the compressor 5 (i.e., the gas-phase flow from the gas-liquid separator 4) have a certain pre-pressure, which is used to advantageously save the compression work of the compressor. For example, in this example, the compressor can omit one compression stage compared with the compressor of a common air conditioning system. It can be seen that in Figure 1 In this air conditioning system, the ejector cycle plays a role in work recovery. Summary of the Invention

[0005] An object of one aspect of the present invention is to provide an improved air conditioning system.

[0006] Another object of the present invention is to provide a control method for the air conditioning system of the foregoing aspect.

[0007] To achieve the foregoing object, one aspect of the present invention provides an air conditioning system having an ejector cycle. The air conditioning system includes a compressor, a condenser, and an evaporator connected in series to form a loop. The ejector cycle includes an ejector, wherein,

[0008] The ejector obtains a high-pressure liquid flow from the condenser and a low-pressure vapor flow or a low-pressure two-phase flow from the evaporator. The high-pressure liquid flow and the low-pressure vapor flow or the low-pressure two-phase flow are mixed into a medium-pressure two-phase flow within the ejector and are delivered to a gas-liquid separator. Among them, the gas-phase flow separated by the gas-liquid separator is delivered to the bearing of the compressor to lubricate the bearing.

[0009] Optionally, in the air-conditioning system as described above, the liquid-phase flow separated by the gas-liquid separator is delivered to the motor of the compressor to cool the motor.

[0010] Optionally, in the air-conditioning system as described above, the liquid obtained by condensation at the motor is collected at the bottom of the motor and returned to the evaporator, or a part of the liquid-phase flow separated by the gas-liquid separator is directly returned to the evaporator.

[0011] Optionally, in the air-conditioning system as described above, the high-pressure liquid flow enters the ejector from the working fluid inlet of the ejector, and the low-pressure vapor flow or the low-pressure two-phase flow enters the ejector from the entrained fluid inlet of the ejector.

[0012] Optionally, in the air-conditioning system as described above, a first throttle valve is provided between the condenser and the working fluid inlet of the ejector, and / or a second throttle valve is provided between the evaporator and the entrained fluid inlet of the ejector.

[0013] Optionally, in the air-conditioning system as described above, the pressure ratio between the mixed fluid outlet and the entrained fluid inlet of the ejector is between 1 and 2.

[0014] Optionally, in the air-conditioning system as described above, the pressure ratio between the mixed fluid outlet and the entrained fluid inlet of the ejector is between 1.2 and 1.8.

[0015] Optionally, in the air-conditioning system as described above, an air storage tank is connected between the gas-phase flow outlet of the gas-liquid separator and the bearing. Before being supplied to the bearing, the gas-phase flow separated by the gas-liquid separator is stored in the air storage tank, and the air storage tank has a controlled temperature and pressure so that no phase change occurs when the gas-phase flow enters the bearing.

[0016] Optionally, in the air-conditioning system as described above, a third throttle valve is provided at the outlet end of the air storage tank to control the gas-phase flow supplied to the bearing.

[0017] To achieve the foregoing object, another aspect of the present invention provides a control method for an air-conditioning system as described in any one of the foregoing aspects, wherein the air supply amount to the bearing is controlled by adjusting the flow rate of at least one of the following various flows:

[0018] The high-pressure liquid flow obtained by the ejector from the condenser;

[0019] The low-pressure steam flow or low-pressure two-phase flow obtained by the ejector from the evaporator; and

[0020] The gas-phase flow delivered to the bearing of the compressor. Description of the Drawings

[0021] With reference to the drawings, the disclosure of the present invention will become more apparent. It should be understood that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In the drawings:

[0022] Figure 1 is a schematic principle diagram of an ejector cycle of the prior art; and

[0023] Figure 2 is a schematic principle diagram of an air-conditioning system according to the present invention, which includes an ejector cycle. Detailed Embodiments

[0024] The detailed embodiments of the present invention will be described in detail below with reference to the drawings. The following description is only an exemplary illustration of the technical solutions of specific embodiments of the present invention and should not be regarded as the whole of the present invention or be regarded as a limitation or restriction on the technical solutions of the present invention.

[0025] In this specification, orientation terms such as top and bottom are defined relative to the orientation shown in the drawings, and these or other orientation terms should not be interpreted as restrictive terms. In addition, expressions such as "first", "second", "third", etc. are only used for descriptive and distinguishing purposes and cannot be understood as indicating or implying the relative importance of the corresponding components.

[0026] Figure 2 is a schematic principle diagram of an air-conditioning system according to the present invention, which includes an ejector cycle.

[0027] As can be seen from Figure 2 In this example, the air-conditioning system 100 may include a compressor 110, a condenser 120, an expansion valve 130, an evaporator 140, etc. that are connected in sequence to form a loop, which are respectively used to implement the compression process, the condensation process, the expansion process, and the evaporation process, so as to perform refrigeration and cooling and air conditioning.

[0028] Specifically, when the air-conditioning system is operating, the compressor 110 discharges high-temperature and high-pressure gaseous refrigerant, which enters the condenser 120 for condensation to become normal-temperature and high-pressure liquid refrigerant (heat dissipation), and then enters the evaporator 140 through the expansion valve 130, where it evaporates (absorbs heat), i.e., refrigeration. After that, the low-pressure gaseous or two-phase refrigerant obtained by evaporation returns to the compressor 110 to continue compression and continue the cycle.

[0029] In an alternative embodiment, according to different specific requirements, the air-conditioning system can omit components unnecessary for the refrigeration cycle in the figure, or implement each component in a different form, or can also add corresponding components according to specific requirements.

[0030] As shown in the figure, an ejector cycle is also provided in the air-conditioning system 100. The ejector cycle may include an ejector 150.

[0031] The ejector 150 has a working fluid inlet 151 and an entrained fluid inlet 152. The high-pressure liquid flow enters the first nozzle of the ejector 150 from the working fluid inlet 151, is converted into a high-speed gas-liquid two-phase flow, and carries away the low-pressure steam flow or low-pressure two-phase flow with a lower pressure entering from the entrained fluid inlet 152. The two enter a mixing chamber (not shown) and mix therein, and then pass through a diffuser chamber (not shown) for pressure recovery. At the outlet of the diffuser chamber, i.e., the mixed fluid outlet 153 of the ejector 150, the pressure of the output mixed fluid (medium-pressure two-phase fluid) is higher than the pressure of the low-pressure steam flow or low-pressure two-phase flow when it enters the receiving chamber.

[0032] Referring to the figure, in this ejector cycle, the ejector 150 can obtain a high-pressure liquid flow from the condenser 120 and a low-pressure steam flow or low-pressure two-phase flow from the evaporator 140. The obtained high-pressure liquid flow and low-pressure steam flow or low-pressure two-phase flow are mixed into a medium-pressure two-phase fluid in the ejector 150 and are transported to the gas-liquid separator 160.

[0033] Here, the function of the gas-liquid separator 160 is to separate the gas and liquid of the medium-pressure two-phase fluid from the ejector 150. In the illustrated example, the separated gas phase flow is output from the top of the gas-liquid separator 160, while the separated liquid phase flow is output from the bottom of the gas-liquid separator 160. In different embodiments, an appropriate type of gas-liquid separator can be selected according to specific requirements, which will not be elaborated here.

[0034] According to the illustrated example, the gas-phase flow separated by the gas-liquid separator 160 is transported to the bearings 112 and 113 of the compressor 110 to be used as the lubricating medium for the bearings. The bearings 112 and 113 are bearings that use refrigerant gas as the lubricant and rely on the elastic deformation of their foil to provide support. They can use air or the like as the lubricant, and in the case of a compressor or the like, the gas-phase working medium can be used as the lubricant. Once these bearings become suspended during use, they require no external control, have no friction, are self-adaptive, have much lower frictional resistance than oil-lubricated bearings, and have a wide applicable speed and temperature range.

[0035] In conventional applications, for such bearings in an air-conditioning system compressor, an additional air source usually needs to be provided, or air is drawn from the compressor, often requiring an additional air pump or the like. However, there are still problems such as unstable air source supply and the presence of liquid-phase components, so the performance of the bearings cannot be optimally achieved, and even the service life of the bearings may be affected. The illustrated embodiment advantageously solves this problem through the combined use of an ejector and a gas-liquid separator, which can not only advantageously ensure the performance of the bearings but also extend the service life of the bearings and improve the stability of system operation.

[0036] According to the illustrated example, the liquid phase separated by the gas-liquid separator 160 is guided to the motor 111 of the compressor 110 and used as the cooling medium for the motor 111 of the compressor 110 to provide cooling for it.

[0037] For a conventional air-conditioning system compressor motor, usually a high-pressure liquid flow is directly drawn from the condenser and sprayed into the motor cavity through a series of cylindrical channels in the circumferential and axial directions of the motor cavity, where flash evaporation occurs to achieve the cooling effect. In contrast, in the illustrated embodiment, by further utilizing the pressure difference between the condenser and the evaporator and through the ejector and related components, two purposes can be achieved simultaneously: providing a stable air supply source for the bearings and providing a cooling source for motor cooling. The cooling of the compressor motor in this embodiment can be used as a supplement to its existing cooling or can be used to cool the motor alone.

[0038] In other embodiments, according to specific needs, the liquid-phase flow separated by the gas-liquid separator can also be used as the cooling medium for other components of the air-conditioning system. In an alternative embodiment, the liquid-phase flow separated by the gas-liquid separator can also be wholly or partly returned to the evaporator for continued circulation.

[0039] According to the embodiment shown in the figure, the working fluid inlet 151 of the ejector 150 is connected to the outlet of the condenser 120, and a first throttle valve 181 may be provided between the working fluid inlet 151 of the ejector 150 and the outlet of the condenser 120. The entrainment fluid inlet 152 of the ejector 150 is connected to the outlet of the evaporator 140, and a second throttle valve 182 may be provided between the entrainment fluid inlet 152 of the ejector 150 and the outlet of the evaporator 140. The mixed fluid outlet 153 of the ejector 150 is connected to the gas-liquid separator 160. The first throttle valve 181 and the second throttle valve 182 can be used to control the flow rate and pressure of the high-pressure liquid flow and the low-pressure steam flow or low-pressure two-phase flow introduced into the ejector 150, thereby realizing the control of the medium-pressure two-phase mixed fluid output by the ejector 150.

[0040] In an alternative embodiment, other equivalent devices of the throttle valve can be used to replace the first throttle valve 181 and the second throttle valve 182 to obtain high-pressure refrigerant liquid and low-pressure refrigerant steam or low-pressure two-phase refrigerant fluid from the condenser 120 and the evaporator 140 respectively. In an alternative embodiment, alternative forms of the throttle valve include, but are not limited to, electronic expansion valves, mechanical valves, etc.

[0041] Combined Figure 2 With the above description, it can be seen that the high-pressure liquid flow enters the ejector 150 from the working fluid inlet 151 of the ejector 150, and the low-pressure steam flow or low-pressure two-phase flow enters the ejector 150 from the entrainment fluid inlet 152 of the ejector 150. As described above, the first throttle valve 181 between the condenser 120 and the working fluid inlet 151 of the ejector 150 and the second throttle valve 182 between the evaporator 140 and the entrainment fluid inlet 152 of the ejector 150 can be used to control and regulate the high-pressure liquid flow from the condenser 120 and the low-pressure steam flow or low-pressure two-phase flow from the evaporator 140 respectively.

[0042] After being mixed by the ejector 150, the medium-pressure two-phase fluid is ejected from the mixed fluid outlet 153 of the ejector 150. The pressure ratio between the mixed fluid outlet 153 of the ejector 150 and the entrainment fluid inlet 152 can be between 1 and 2. In an alternative embodiment, the pressure ratio between the mixed fluid outlet 153 of the ejector 150 and the entrainment fluid inlet 152 can be between 1.2 and 1.8. The provision of the above pressure ratio can help the liquid phase flow separated by the gas-liquid separator 160 to be ejected into the motor chamber to play a cooling role, preventing the cooling effect from being weakened due to pressure loss. When the motor is cooled, the liquid phase flow ejected into the motor chamber undergoes flashing and rapidly vaporizes to absorb heat, thereby achieving a good cooling effect.

[0043] As described above, the medium-pressure two-phase fluid mixed by the ejector 150 is transported to the gas-liquid separator 160, where the medium-pressure two-phase fluid is separated into a gas-phase flow and a liquid-phase flow. The gas-liquid separator 160 has a gas-phase flow outlet and a liquid-phase flow outlet; in the illustrated example, the gas-phase flow outlet and the liquid-phase flow outlet are respectively located at the top and bottom of the gas-liquid separator 160.

[0044] In this example, the gas-phase flow outlet can be connected to a gas storage tank 170, and the gas storage tank 170 communicates with the bearings 112, 113 of the compressor 110 via a third throttle valve 183. Thus, the gas-phase flow separated by the gas-liquid separator 160 can be used as a lubricating medium for the bearings 112, 113, and an oil-free solution for compressor bearing lubrication can be achieved. This oil-free solution has low maintenance costs; it is also less costly compared to magnetic bearings.

[0045] In addition, the gas supply source achieved through the gas storage tank 170 is stable without the need for an additional pump, which is crucial for the performance of the bearings.

[0046] In other alternative embodiments, according to specific requirements, the gas-phase flow separated by the gas-liquid separator 160 can also be used for other purposes besides the lubricating medium. For example, a part of the gas-phase flow separated by the gas-liquid separator 160 can also be returned to the inlet of the compressor 110 to achieve the purpose of saving some compression work.

[0047] The illustrated embodiment utilizes the ejector cycle to simultaneously provide both the supply of the lubricating medium for the bearings 112, 113 of the compressor 110 and the supply of the cooling medium for the motor 111 of the compressor 110. Without changing the existing compressor design, there is no loss of compressor work, and there are few changes to the prior art during application, so it is easy to implement.

[0048] It can be seen that according to the illustrated embodiment, the gas-phase separated by the gas-liquid separator 160 can be used as a lubricating medium for the bearings 112, 113 of the compressor 110. The gas-phase outlet of the gas-liquid separator 160 can be connected to a gas storage tank 170, and the separated gas-phase can be stored in the gas storage tank 170 before being used for the bearings 112, 113. The gas storage tank 170 can also have controlled temperature and pressure, so that no phase change occurs when the gas-phase flows into the bearings 112, 113. The third throttle valve 183 provided at the outlet end of the gas storage tank 170 can be used to control the gas-phase supplied to the bearings 112, 113. In different embodiments, according to specific circumstances, the gas storage tank 170 and / or the third throttle valve 183 downstream thereof can be omitted.

[0049] In alternative embodiments, other equivalent devices of the throttle valve can be used to replace the third throttle valve 183. In alternative embodiments, optional forms of the throttle valve include, but are not limited to, electronic expansion valves, mechanical valves, etc.

[0050] Furthermore, it can also be seen from Figure 2 that a collecting device, such as a collecting bottom shell, is provided below the compressor 110. On the one hand, it can act as a housing to prevent impurities from entering, and on the other hand, it can also collect and store the liquid obtained by condensation, dissipate part of the heat, etc. The collecting device can be connected to the evaporator. Through this collecting device, the liquid obtained by steam condensation at its motor 111 can be stored at the bottom of the motor and returned to the evaporator. Figure 2 The loop for returning the liquid to the evaporator is shown in

[0051]

[0052] In addition, another aspect of the present invention also provides a control method for an air-conditioning system as described in any one of the foregoing embodiments. In this method, the air supply volume to the bearing can be controlled by adjusting the flow rate of at least one of the following various flows: the high-pressure liquid flow obtained by the ejector from the condenser; the low-pressure steam flow or low-pressure two-phase flow obtained by the ejector from the evaporator; and the gas-phase flow delivered to the bearing of the compressor. By this control method, using the air-conditioning system of the foregoing embodiments, at least the air supply to the compressor bearing can be advantageously achieved to adapt to specific working conditions. The technical scope of the present invention is not limited only to the content described above. Those skilled in the art can make various deformations, modifications or combinations to the above embodiments without departing from the technical idea of the present invention, and these deformations, modifications or combinations should all fall within the scope of the present invention.

[0053] List of Reference Numerals

[0054] 1 Ejector

[0055] 2 Condenser

[0056] 3 Evaporator

[0057] 4 Gas-liquid Separator

[0058] 5 Compressor

[0059] 100 Air-conditioning System

[0060] 110 Compressor

[0061] 111 Motor

[0062] 112, 113 Bearings

[0063] 120 Condenser

[0064] 130 Expansion Valve

[0065] 140 Evaporator

[0066] 150 Injector

[0067] 151 Working fluid inlet

[0068] 152 Ejector fluid inlet

[0069] 153 Mixed fluid outlet

[0070] 160 Gas-liquid separator

[0071] 170 Gas storage tank

[0072] 181 First throttle valve

[0073] 182 Second throttle valve

[0074] 183 Third throttle valve

Claims

1. An air conditioning system with an ejector cycle, characterized in that, The air conditioning system includes a compressor, a condenser, and an evaporator that are connected in sequence to form a loop. The ejector cycle includes an ejector. Among them, the ejector obtains a high-pressure liquid flow from the condenser and a low-pressure steam flow or a low-pressure two-phase flow from the evaporator. The high-pressure liquid flow and the low-pressure steam flow or the low-pressure two-phase flow are mixed into a medium-pressure two-phase flow in the ejector and are delivered to a gas-liquid separator. Among them, the gas-phase flow separated by the gas-liquid separator is delivered to the bearing of the compressor to lubricate the bearing.

2. The air conditioning system according to claim 1, wherein, The liquid-phase flow separated by the gas-liquid separator is delivered to the motor of the compressor to cool the motor.

3. The air conditioning system according to claim 2, wherein The liquid obtained by condensation at the motor is collected at the bottom of the motor and returned to the evaporator. Alternatively, a part of the liquid-phase flow separated by the gas-liquid separator is directly returned to the evaporator.

4. The air conditioning system according to claim 1, wherein The high-pressure liquid flow enters the ejector from the working fluid inlet of the ejector, and the low-pressure steam flow or the low-pressure two-phase flow enters the ejector from the entrained fluid inlet of the ejector.

5. The air conditioning system according to claim 4, wherein, A first throttle valve is provided between the condenser and the working fluid inlet of the ejector, and / or a second throttle valve is provided between the evaporator and the entrained fluid inlet of the ejector.

6. The air conditioning system according to claim 5, wherein, The pressure ratio between the mixed fluid outlet and the entrained fluid inlet of the ejector is between 1 and 2.

7. The air-conditioning system according to claim 6, wherein, The pressure ratio between the mixed fluid outlet and the entrained fluid inlet of the ejector is between 1.2 and 1.

8.

8. The air conditioning system according to claim 1, wherein, A gas storage tank is connected between the gas-phase flow outlet of the gas-liquid separator and the bearing. Before being supplied to the bearing, the gas-phase flow separated by the gas-liquid separator is stored in the gas storage tank, and the gas storage tank has a controlled temperature and pressure so that no phase change occurs when the gas-phase flow enters the bearing.

9. The air-conditioning system according to claim 8, wherein, A third throttle valve is provided at the outlet end of the gas storage tank to control the gas-phase flow supplied to the bearing.

10. A control method for an air conditioning system according to any one of the preceding claims 1 to 9, wherein the air supply amount to the bearing is controlled by adjusting the flow rate of at least one of the following flows: the high-pressure liquid flow obtained by the ejector from the condenser; the low-pressure steam flow or the low-pressure two-phase flow obtained by the ejector from the evaporator; and the gas-phase flow delivered to the bearing of the compressor.

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