CN114543206A - Air conditioning system and control method thereof - Google Patents

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 connected in sequence in a loop, the ejector cycle including an ejector, wherein the ejector draws a high pressure liquid flow from the condenser and A low-pressure vapor stream or low-pressure two-phase stream is obtained from the evaporator, and the high-pressure liquid stream and the low-pressure vapor stream or low-pressure two-phase stream are mixed into a medium-pressure two-phase stream in the ejector and delivered to the gas-liquid A separator, wherein the gas-phase stream separated by the gas-liquid separator is delivered to the bearing of the compressor to lubricate the bearing.

Description

Air conditioning system and control method thereof

technical field

The present invention relates to the technical field of air conditioning; in particular, the present invention relates to an air conditioning system with an ejector cycle, and further relates to a control method of the air conditioning system.

Background technique

The air conditioning system is a conventional system for air conditioning and air quality improvement, in which the bearing of the compressor usually uses lubricating oil as the lubricating medium.

Compared with compressors that use lubricating oil as the lubricating medium, oil-free compressors can save the entire oil circuit system, save space and save costs. In this case, as an oil-free solution, the bearing of an oil-free compressor has the advantages of an oil-free lubrication system and low maintenance costs. In addition, gas is less viscous than lubricating oil, has high temperature resistance, and is non-polluting; at the same time, using this type of bearing is cheaper and has simpler control logic than the solution using magnetic bearings. The lubricating medium of this kind of bearing can be realized by bleed air from the primary or secondary stage of the compressor, which often needs to change the design of the compressor; in addition, the bleed air from the compressor also has hidden dangers that affect the performance of the compressor.

An air conditioning system with an ejector cycle is shown in FIG. 1 . In the illustrated ejector cycle, ejector 1 obtains a high pressure liquid stream from condenser 2 as a working stream, and a low pressure vapor stream or a low pressure two-phase stream from evaporator 3 as a pilot stream, both of which flow in the ejector 1 is mixed 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 is returned to the evaporator 3, and the obtained gas-phase flow is sent to the compressor 5 for direct use as a refrigeration medium. participate in the refrigeration cycle. In such a system of Figure 1, the ejector cycle is provided so that the input to the compressor 5 (ie the gas phase stream from the gas-liquid separator 4) has a certain pre-pressure for advantageously saving the compression work of the compressor. For example, in this example, it is made possible to omit one compression stage from the compressor compared to a compressor of a conventional air conditioning system. It can be seen that in the air conditioning system of FIG. 1 , the ejector cycle plays the role of work recovery.

SUMMARY OF THE INVENTION

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

Another object of the present invention is to provide a control method of the air conditioning system of the aforementioned aspect.

To achieve the foregoing objects, one aspect of the present invention provides an air conditioning system having an ejector cycle, the air conditioning system including a compressor, a condenser and an evaporator connected in sequence in a circuit, the ejector cycle including an ejector ,in,

The ejector takes 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 vapour or low pressure two-phase flow at the ejector. It is mixed into a medium-pressure two-phase flow and sent to the gas-liquid separator, wherein the gas-phase flow separated by the gas-liquid separator is sent to the bearing of the compressor to lubricate the bearing.

Optionally, in the aforementioned air conditioning system, the liquid phase stream separated by the gas-liquid separator is sent to the motor of the compressor to cool the motor.

Optionally, in the aforementioned air-conditioning system, the liquid obtained by condensation at the motor is collected at the bottom of the motor and returned to the evaporator, or the liquid separated by the gas-liquid separator. A portion of the phase flow is returned directly to the evaporator.

Optionally, in the aforementioned air conditioning system, 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 exits the ejector from the working fluid inlet. A fluid inlet is ejected into the injector.

Optionally, in the aforementioned air conditioning system, a first throttle valve is provided between the condenser and the working fluid inlet of the ejector, and/or, the evaporator and the ejector A second throttle valve is arranged between the ejection fluid inlets.

Optionally, in the aforementioned air conditioning system, the pressure ratio between the mixed fluid outlet of the ejector and the injection fluid inlet is between 1 and 2.

Optionally, in the aforementioned air conditioning system, the pressure ratio between the mixed fluid outlet of the ejector and the injection fluid inlet is between 1.2 and 1.8.

Optionally, in the aforementioned air conditioning system, a gas storage tank is connected between the gas-phase outflow port of the gas-liquid separator and the bearing, and the gas-liquid separation is performed before being supplied to the bearing. The gas phase stream separated by the separator is stored in the gas tank, and the gas tank has a controlled temperature and pressure so that no phase change occurs when the gas phase stream enters the bearing.

Optionally, in the aforementioned air conditioning system, the outlet end of the air storage tank is provided with a third throttle valve to control the flow of the gas phase supplied to the bearing.

In order to achieve the foregoing object, another aspect of the present invention provides a control method of an air conditioning system as described in any one of the foregoing aspects, wherein the flow rate to the bearing is controlled by adjusting the flow rate of at least one of the following streams Air supply:

the high pressure liquid stream obtained by the eductor from the condenser;

a low-pressure vapor stream or a low-pressure two-phase stream obtained by the eductor from the evaporator; and

The gas phase stream delivered to the bearing of the compressor.

Description of drawings

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

Figure 1 is a schematic schematic diagram of a prior art injector cycle; and

Figure 2 is a schematic schematic diagram of an air conditioning system according to the present invention, including an ejector cycle.

Detailed ways

Specific embodiments of the present invention will be described in detail below with reference to the accompanying 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 as a limitation or limitation on the technical solutions of the present invention.

Orientation terms such as top, bottom, etc. mentioned in this specification are defined relative to the orientation shown in the drawings, and these or other orientation terms should not be construed as limiting terms. In addition, the terms "first", "second", "third" and other expressions are only used for the purpose of description and distinction, and should not be construed as indicating or implying the relative importance of the corresponding components.

Figure 2 is a schematic schematic diagram of an air conditioning system according to the present invention, including an ejector cycle.

As can be seen from FIG. 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., which are sequentially connected in a loop, and are used to realize the compression process, the condensation process, the expansion process, and the like, respectively. process, evaporation process, so as to perform refrigeration and air conditioning.

Specifically, when the air-conditioning system is in operation, the compressor 110 discharges the high-temperature and high-pressure gas-phase refrigerant, enters the condenser 120 for condensation into a normal-temperature and high-pressure liquid refrigerant (heat dissipation), and then enters the evaporator 140 through the expansion valve 130, where in the evaporator Evaporation (heat absorption) is carried out within 140, that is, refrigeration. After that, the low-pressure gaseous or two-phase refrigerant obtained by evaporation is returned to the compressor 110 to continue to compress and continue to circulate.

In an optional embodiment, according to different specific needs, the air-conditioning system can omit the components that are unnecessary for the refrigeration cycle in the figure, or implement each component in a different form, or add corresponding components according to specific needs. part.

As shown, an ejector cycle is also provided in the air conditioning system 100 . The injector cycle may include injector 150 .

The ejector 150 has a working fluid inlet 151 and an ejection fluid inlet 152 . The high-pressure liquid flow enters the first nozzle of the ejector 150 from the working fluid inlet 151 , and is converted into a high-speed gas-liquid two-phase flow. The incoming, lower pressure low pressure vapor stream or low pressure two-phase stream is carried away, the two enter and mix in a mixing chamber (not shown), and then pass through a diffusion chamber (not shown) for pressure recovery. At the outlet of the diffusion chamber, that is, 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 the low-pressure two-phase flow entering the receiving chamber.

Referring to the illustration, in this ejector cycle, the ejector 150 may take a high pressure liquid flow from the condenser 120 and a low pressure vapor flow or a low pressure two-phase flow from the evaporator 140, the resulting high pressure liquid flow and low pressure vapor flow or low pressure The two-phase flow is mixed into a medium-pressure two-phase fluid in the ejector 150 and sent to the gas-liquid separator 160 .

Here, the function of the gas-liquid separator 160 is to separate the gas-liquid of the medium-pressure two-phase fluid from the ejector 150 . In the illustrated example, the separated gas-phase stream is output from the top of the gas-liquid separator 160 , and the separated liquid-phase stream is output from the bottom of the gas-liquid separator 160 . In different implementations, an appropriate type of gas-liquid separator can be selected according to specific needs, which will not be repeated here.

According to the illustrated example, the gas-phase stream separated by the gas-liquid separator 160 is delivered to the bearings 112, 113 of the compressor 110 to be used as a lubricating medium for the bearings. Bearings 112 and 113 are bearings that use refrigerant gas as a lubricant and support the elastic deformation of their foils. They can use air or the like as a lubricant, and in the case of a compressor, a gas-phase working medium can be used as a lubricant. agent. Once these bearings are suspended in use, they do not require external control and are frictionless and self-adaptive. Their frictional resistance is much lower than that of oil-lubricated bearings, and they are applicable to a wide range of speeds and temperatures.

In conventional applications, such bearings in air conditioning system compressors usually need to provide additional air source, or bleed air from the compressor, often requiring another air pump, etc., but there are still problems such as unstable air source supply and liquid-phase components. Therefore, the performance of the bearing cannot be optimally achieved, and even the service life of the bearing can be affected. The illustrated embodiment advantageously solves this problem through the combined use of the ejector and the gas-liquid separator, which can not only favorably ensure the performance of the bearing, but also prolong the service life of the bearing, and can improve the stability of the system operation.

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 to be used as a cooling medium for the motor 111 of the compressor 110 to provide cooling thereto.

For conventional compressor motors of air-conditioning systems, high-pressure liquid flow is usually extracted directly from the condenser, and injected into the motor cavity through a series of cylindrical holes in the circumferential and axial directions of the motor cavity to flash and achieve cooling effect. In contrast to this, in the illustrated embodiment, the pressure difference between the condenser and the evaporator is further utilized, and through the ejector and related components, two purposes can be achieved at the same time: not only can provide a stable air supply source for the bearing, but also Motor cooling provides a cooling source. The cooling of the compressor motor in this embodiment can be used as a supplement to its existing cooling, or it can be used to cool the motor alone.

In other embodiments, according to specific needs, the liquid phase stream separated by the gas-liquid separator can also be used as a cooling medium for other components of the air conditioning system. In an optional embodiment, all or part of the liquid phase stream separated by the gas-liquid separator can also be returned to the evaporator to continue the circulation.

According to the embodiment as shown, the working fluid inlet 151 of the ejector 150 is connected to the outlet of the condenser 120, and a first throttle may be provided between the working fluid inlet 151 of the ejector 150 and the outlet of the condenser 120 valve 181. The ejection 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 ejection 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 . These throttle valves 181 and 182 can be used to realize the flow control and pressure control of the high-pressure liquid flow and the low-pressure steam flow or the low-pressure two-phase flow introduced into the ejector 150 , thereby realizing the medium-pressure two-phase mixed fluid output from the ejector 150 . control.

In an alternative embodiment, the first and second throttle valves 181 and 182 can be replaced by other equivalent devices of throttle valves, respectively obtaining high pressure refrigerant liquid and low pressure refrigerant vapor from the condenser 120 and evaporator 140 or Low pressure two-phase refrigerant fluid. In alternative embodiments, alternative forms of throttle valves include, but are not limited to, electronic expansion valves, mechanical valves, and the like.

2 and 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 the low pressure two-phase flow enters the ejector 150 from the ejection fluid inlet 152 of the ejector 150. . As previously described, 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 ejection fluid inlet 152 of the ejector 150 may be For the control and regulation of high pressure liquid flow from condenser 120 and low pressure vapor flow or low pressure two-phase flow from evaporator 140, respectively.

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 injection fluid inlet 152 may be between 1 and 2. In alternative embodiments, the pressure ratio between the mixing fluid outlet 153 and the injection fluid inlet 152 of the injector 150 may be between 1.2 and 1.8. The provision of the above-mentioned pressure ratio can help to make the liquid phase flow separated by the gas-liquid separator 160 spray into the motor cavity to play a cooling effect, so as to prevent the cooling effect from being weakened due to pressure loss. When the motor is cooled, the liquid phase flow injected into the motor cavity flashes, vaporizes rapidly and absorbs heat to achieve a good cooling effect.

As previously described, the medium-pressure two-phase fluid mixed by the ejector 150 is delivered 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-liquid outflow port and a liquid-phase outflow port; in the illustrated example, the gas-liquid outflow port and the liquid-phase outflow port are located at the top and the bottom of the gas-liquid separator 160 , respectively.

In this example, the gas-phase outflow port may be connected with a gas storage tank 170 , and the gas storage tank 170 is connected to the bearings 112 and 113 of the compressor 110 via the third throttle valve 183 , so that the gas phase separated by the gas-liquid separator 160 The flow can be used as a lubricating medium for bearings 112, 113, enabling an oil-free solution for compressor bearing lubrication. This oil-free solution is low maintenance; less expensive than magnetic bearings.

In addition, the gas supply through the gas tank 170 is stable without the need for an additional pump, which is critical to the performance of the bearing.

In other optional embodiments, the gas-phase stream separated by the gas-liquid separator 160 may also be used for other purposes than the lubricating medium according to specific needs. For example, a part of the gas-phase stream separated by the gas-liquid separator 160 may also be returned to the inlet of the compressor 110 to save part of the compression work.

The illustrated embodiment utilizes an ejector cycle to simultaneously provide both a supply of lubricating medium to the bearings 112, 113 of the compressor 110 and a supply of cooling medium to the motor 111 of the compressor 110 without changing existing compressor designs and without loss of compression The machine works, and there are few changes to the existing technology during application, so it is easy to implement.

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

In alternative embodiments the third throttle valve 183 may be replaced with other equivalent means of a throttle valve. In alternative embodiments, alternative forms of throttle valves include, but are not limited to, electronic expansion valves, mechanical valves, and the like.

Further, it can also be seen from FIG. 2 that a collection device, such as a collection bottom casing, is provided below the compressor 110, which on the one hand can be used as a shell to prevent the entry of impurities, and on the other hand can also collect and store the condensed liquid obtained , dissipate some heat, etc. The collection device may be in communication with the evaporator. With this collection device, the liquid resulting from the condensation of the vapor at its motor 111 can be stored at the bottom of the motor and returned to the evaporator. A circuit for the return of liquid to the evaporator is shown in FIG. 2 , either back at the refrigerant inlet of the evaporator 140 or into the evaporator 140 through a separate channel.

In addition, another aspect of the present invention also provides a control method of an air conditioning system according to any one of the foregoing embodiments. In this method, the air supply to the bearing can be controlled by adjusting the flow rate of at least one of the following streams: the high pressure liquid flow obtained by the eductor from the condenser; the low pressure steam flow obtained by the eductor from the evaporator or the low pressure two phase flow; and gas phase flow delivered to the bearing of the compressor. Through this control method, using the air conditioning systems of the foregoing embodiments, at least the air supply to the compressor bearing can be advantageously realized so as to adapt it to the specific working conditions.

The technical scope of the present invention is not limited to the content in the above description, and those skilled in the art can make various deformations, modifications or combinations to the above-mentioned 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.

List of reference signs

1 injector

2 condenser

3 Evaporator

4 Gas-liquid separator

5 Compressor

100 Air Conditioning Systems

110 Compressor

111 Motor

112, 113 Bearings

120 Condenser

130 Expansion valve

140 Evaporator

150 injectors

151 Working fluid inlet

152 Injector fluid inlet

153 Mixed fluid outlet

160 Gas-liquid separator

170 Gas Tank

181 First throttle valve

182 Second throttle valve

183 Third throttle valve

Claims (10)

1. An air conditioning system having an ejector cycle comprising an ejector, wherein,

the ejector takes a high pressure liquid stream from the condenser and a low pressure steam stream or a low pressure two-phase stream from the evaporator, the high pressure liquid stream and the low pressure steam stream or the low pressure two-phase stream are mixed into an intermediate pressure two-phase stream within the ejector and delivered to a gas-liquid separator, wherein the gas-liquid separator delivers the separated gas-phase stream to bearings of the compressor to lubricate the bearings.

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

3. The air conditioning system of claim 2, wherein liquid condensed at the motor is collected at the bottom of the motor and returned to the evaporator, or a portion of the liquid phase stream separated by the gas-liquid separator is returned directly to the evaporator.

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

5. An air conditioning system as claimed in 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 ejector fluid inlet of the ejector.

6. The air conditioning system of claim 5, wherein the ejector has a pressure ratio between the mixing fluid outlet and the ejector fluid inlet of between 1 and 2.

7. The air conditioning system of claim 6, wherein a pressure ratio between the mixed fluid outlet of the ejector and the ejector fluid inlet is between 1.2 and 1.8.

8. The air conditioning system as claimed in claim 1, wherein an air tank is connected between a gas phase outflow port of the gas-liquid separator and the bearing, the gas phase flow separated by the gas-liquid separator is stored in the air tank before being supplied to the bearing, and the air tank has a temperature and pressure controlled so that a phase change does not occur when the gas phase flow enters the bearing.

9. The air conditioning system of claim 8, wherein an outlet end of the air reservoir is provided with a third throttle valve to control the flow of gas phase supplied to the bearing.

10. A control method of an air conditioning system as claimed in any one of the preceding claims 1 to 9, wherein the amount of air supplied to the bearing is controlled by adjusting the flow rate of at least one of the following streams:

a high pressure liquid stream taken by the ejector from the condenser;

a low pressure steam stream or a low pressure two-phase stream taken by the ejector from the evaporator; and

a gas phase flow delivered to bearings of the compressor.

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