Refrigerant circulation system and air conditioning system

Abstract

The present application relates to a refrigerant circulation system and an air conditioning system, the refrigerant circulation system comprising: a compressor (3); a condenser (4) fluidly connected to a discharge port of the compressor (3); a first throttling component (11) fluidly connected to the condenser (4) and configured to throttle refrigerant condensed by the condenser (4); an evaporator (1) comprising an inlet fluidly connected to the first throttling component (11) to introduce refrigerant throttled by the first throttling component (11) and an outlet fluidly connected to a suction port of the compressor (3); and an oil separator (2) comprising a first refrigerant flow channel fluidly connected to the evaporator (1), a second refrigerant flow channel configured to exchange heat with the first refrigerant flow channel and fluidly connected to a discharge port of the compressor (3), and a lubricating oil outlet in communication with the first refrigerant flow channel.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of refrigeration technology, in particular to a refrigerant circulation system and an air conditioning system. BACKGROUND

[0002] In a water chiller, for a compressor using oil-lubricated bearings, oil leakage often occurs during operation, mainly because when the lubricating oil enters the compressor lubricating bearing, the lubricating oil will directly contact the refrigerant in the compressor, and after the two are mixed, oil-containing refrigerant is formed, which finally enters the evaporator of the water chiller. In the evaporator, the oil-containing refrigerant contacts the heat exchange tube, directly causing the heat exchange effect to deteriorate, and the increase in the heat exchange temperature difference leads to an increase in the power consumption of the unit and a decrease in performance. At the same time, if the unit leaks oil into the evaporator for a long time, the oil level in the oil tank will decrease, and the pressure difference before and after oil supply by the oil pump will decrease, leading to protection shutdown of the unit and directly affecting the normal use of the unit.

[0003] To solve the problem of oil leakage, the current conventional solution is to ensure the oil return of the unit by twice injection. The first-stage injection uses high-pressure gas from the condenser to inject the oil-containing refrigerant in the evaporator to the suction port of the compressor, and the low pressure of the suction port causes the refrigerant to evaporate, and the lubricating oil separates therefrom. The second-stage injection also uses high-pressure gas from the top of the condenser to inject the separated lubricating oil in the bottom cavity of the compressor to the oil tank. However, this solution also has two problems, cannot cope with various working conditions, and leads to oil leakage in the actual operation of the unit after sale. First, the injection power is insufficient to cover all working conditions: in order to play the role of the injector, high-pressure fluid must be used as the main injection flow to drive the injection of low-pressure fluid. However, when the unit is operated in a low-pressure difference and low-load working condition, the pressure difference between the condenser and the evaporator is very small, the injector is basically ineffective, leading to difficulty in oil return, and at this time, the unit is more prone to oil leakage. Second, the heat of evaporation and separation is insufficient: the conventional first-stage injection to the suction port of the compressor causes the refrigerant to be unable to completely evaporate from the lubricating oil due to the lowest temperature of the suction port, and the conventional second-stage injection to the oil tank to absorb the heat of the oil tank for evaporation has the disadvantages of reducing the temperature and viscosity of the lubricating oil on one hand, and on the other hand, when the unit encounters a low-pressure difference and low-load medium-temperature working condition (especially the unit applied in a data center, which often operates in this working condition in winter), the temperature of the oil tank is only about 20℃, and the refrigerant is also difficult to separate. SUMMARY

[0004] The present application aims to provide a refrigerant circulation system and an air conditioning system to improve the problem that the lubricating oil in the evaporator is not easy to separate from the refrigerant in the prior art.

[0005] According to one aspect of an embodiment of the present application, the present application provides a refrigerant circulation system, which comprises:

[0006] a compressor;

[0007] a condenser fluidly connected to a discharge port of the compressor;

[0008] a first throttling component fluidly connected to the condenser and configured to throttle the refrigerant condensed by the condenser;

[0009] an evaporator including an inlet fluidly connected to the first throttling component to introduce the refrigerant throttled by the first throttling component and an outlet fluidly connected to a suction port of the compressor;

[0010] an oil separator including a first refrigerant flow passage fluidly connected to the evaporator, a second refrigerant flow passage configured to exchange heat with the first refrigerant flow passage and fluidly connected to the discharge port of the compressor, and a lubricating oil outlet in communication with the first refrigerant flow passage.

[0011] In some embodiments, a height of the oil separator relative to the evaporator is configured such that a liquid in the evaporator can flow to the first refrigerant flow passage of the oil separator under the action of gravity.

[0012] In some embodiments, the oil separator is not higher than a bottom of the evaporator.

[0013] In some embodiments,

[0014] the inlet of the first refrigerant flow passage is fluidly connected to the evaporator, and the outlet of the first refrigerant flow passage is fluidly connected to the evaporator; and / or

[0015] the inlet of the second refrigerant flow passage is fluidly connected to the discharge port of the compressor, and the outlet of the second refrigerant flow passage is fluidly connected to the suction port of the compressor.

[0016] In some embodiments, the refrigerant circulation system further includes a flasher including an inlet fluidly connected to the condenser, a liquid refrigerant outlet fluidly connected to the evaporator, and a gaseous refrigerant outlet fluidly connected to the charge port of the compressor, and the outlet of the second refrigerant flow passage is fluidly connected to the flasher.

[0017] In some embodiments, the oil separator includes a shell-and-tube heat exchanger, a tube side of the shell-and-tube heat exchanger being the first refrigerant flow passage, and a shell side of the shell-and-tube heat exchanger being the second refrigerant flow passage.

[0018] In some embodiments, the inlet of the first refrigerant flow passage is lower than the outlet of the first refrigerant flow passage.

[0019] In some embodiments, the inlet of the second refrigerant flow passage is upstream of the condenser in a refrigerant flow direction.

[0020] In some embodiments, the refrigerant circulation system further includes:

[0021] an oil tank;

[0022] an oil pump fluidly connected to the oil tank and configured to deliver lubricating oil to the compressor;

[0023] a first ejector including an ejecting fluid inlet fluidly connected to an outlet of the oil pump, an ejected fluid inlet fluidly connected to the lubricating oil outlet of the oil separator, and an outlet fluidly connected to the oil tank.

[0024] In some embodiments, the refrigerant circulation system further comprises a second ejector including an ejecting fluid inlet fluidly connected to the condenser, an ejected fluid inlet fluidly connected to the lubricating oil outlet of the oil separator, and an outlet fluidly connected to the oil tank.

[0025] In some embodiments, the refrigerant circulation system further comprises:

[0026] a first electromagnetic valve configured to control the opening and closing of the outlet of the oil pump and the ejecting fluid inlet of the first ejector;

[0027] a second electromagnetic valve configured to control the opening and closing of the condenser and the ejecting fluid inlet of the second ejector;

[0028] a controller signal connected to the first electromagnetic valve and the second electromagnetic valve respectively, and configured to execute the opening of the first electromagnetic valve and the closing of the second electromagnetic valve in response to a pressure difference ΔP1 of the condensing pressure of the refrigerant in the condenser and the evaporating pressure of the refrigerant in the evaporator being less than a reference pressure difference ΔP, and / or execute the closing of the first electromagnetic valve and the opening of the second electromagnetic valve in response to the pressure difference ΔP1 of the condensing pressure of the refrigerant in the condenser and the evaporating pressure of the refrigerant in the evaporator being greater than the reference pressure difference ΔP by a predetermined value.

[0029] In some embodiments, the refrigerant circulation system further comprises a first pressure sensor for detecting the oil pressure of the oil tank and a second pressure sensor for detecting the oil pressure of the lubricating oil output by the oil pump, the controller being signal connected to the first pressure sensor and the second pressure sensor respectively and taking the difference of the pressures detected by the second pressure sensor and the first pressure sensor as the reference pressure difference ΔP.

[0030] In some embodiments, the lubricating oil outlet is located at a middle portion of the first refrigerant flow passage in terms of height.

[0031] According to another aspect of the present application, there is also provided an air conditioning system comprising the above refrigerant circulation system.

[0032] By applying the technical solution of the present application, in the present embodiment, the high-temperature refrigerant discharged by the compressor is used to heat the refrigerant mixed with lubricating oil in the evaporator, so as to evaporate the refrigerant and separate the refrigerant from the lubricating oil. The two fluids with the largest temperature difference in the refrigerant circulation system are used to perform heat exchange, so as to quickly separate the refrigerant from the oil.

[0033] Other features and advantages of the invention will become clear from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 A schematic diagram of the refrigerant circulation system according to an embodiment of the present invention is shown.

[0036] In the diagram: 1. Evaporator; 2. Oil separator; 3. Compressor; 4. Condenser; 5. Oil tank; 6. Oil pump; 7. First solenoid valve; 8. First ejector; 9. Second solenoid valve; 10. Second ejector; 11. First throttling component; 12. Flash evaporator; 13. Second throttling component. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] like Figure 1 As shown, the refrigerant circulation system in this embodiment includes a compressor 3, a condenser 4, an evaporator 1, and an oil separator 2.

[0039] The condenser 4 is fluidly connected to the exhaust port of the compressor 3; the first throttling component 11 is fluidly connected to the condenser 4 and configured to throttle the refrigerant after it has been condensed by the condenser 4; the evaporator 1 includes an inlet fluidly connected to the first throttling component 11 to introduce the refrigerant after it has been throttled by the first throttling component 11 and an outlet fluidly connected to the suction port of the compressor 3; the oil separator 2 includes a first refrigerant flow channel fluidly connected to the evaporator 1, a second refrigerant flow channel configured to exchange heat with the first refrigerant flow channel and fluidly connected to the exhaust port of the compressor 3, and a lubricating oil outlet communicating with the first refrigerant flow channel.

[0040] In the embodiment, the high-temperature refrigerant discharged by the compressor 3 is used to heat the refrigerant mixed with lubricating oil in the evaporator 1 to evaporate the refrigerant, so that the refrigerant is separated from the lubricating oil. The heat exchange between the two fluids with the maximum temperature difference in the refrigerant circulation system is used to quickly separate the refrigerant from the oil.

[0041] In some embodiments, the height of the oil separator 2 relative to the evaporator 1 is configured such that the liquid in the evaporator 1 can flow to the first refrigerant flow channel of the oil separator 2 under the action of gravity. The refrigerant to be separated from the lubricating oil is transported to the separator by gravity, which is beneficial to simplify the structure and reduce energy consumption.

[0042] In some embodiments, the oil separator 2 is not higher than the bottom of the evaporator 1. The refrigerant to be separated from the lubricating oil flows to the oil separator under the action of gravity, which is beneficial to simplify the structure and reduce energy consumption.

[0043] In some embodiments, the inlet of the first refrigerant flow channel is fluidly connected to the evaporator 1, the outlet of the first refrigerant flow channel is fluidly connected to the evaporator 1, and the refrigerant separated from the lubricating oil returns to the evaporator to continue evaporation and then is transported to the suction port of the compressor, which is beneficial to ensure the improvement of the refrigeration effect of the evaporator and the efficiency of the refrigerant circulation system.

[0044] The inlet of the second refrigerant flow channel is fluidly connected to the exhaust port of the compressor 3, and the outlet of the second refrigerant flow channel is fluidly connected to the suction port of the compressor 3. The refrigerant after heat exchange with the first refrigerant flow channel returns to the suction port of the compressor to ensure the amount of refrigerant in the refrigerant circulation system.

[0045] In some embodiments, the refrigerant circulation system further comprises a flash evaporator 12, the flash evaporator 12 comprises an inlet fluidly connected to the condenser 4, a liquid refrigerant outlet fluidly connected to the evaporator 1, and a gaseous refrigerant outlet fluidly connected to the charge port of the compressor 3, and the outlet of the second refrigerant flow channel is fluidly connected to the flash evaporator 12. The refrigerant after heat exchange with the refrigerant in the first refrigerant flow channel enters the flash evaporator for gas-liquid separation, which is beneficial to reduce the probability of liquid refrigerant carried by the refrigerant introduced into the suction port of the compressor, and also beneficial to ensure and improve the liquid refrigerant introduced into the evaporator to improve the refrigeration capacity of the evaporator.

[0046] Specifically, after the condensed refrigerant enters the flash evaporator 12, part of the refrigerant evaporates to absorb heat, and a gaseous refrigerant outlet is provided at the top of the flash evaporator 12, and the gaseous refrigerant outlet is in communication with the suction port of the compressor 3.

[0047] In the embodiment, the compressor 3 comprises a first-stage compression part and a second-stage compression part in communication with the first-stage compression part to compress the refrigerant compressed by the first-stage compression part, and the charge port is located between the first-stage compression part and the second-stage compression part in the refrigerant flow direction to supplement the refrigerant to the second-stage compression part. In some embodiments, the compressor 3 is a centrifugal compressor.

[0048] In some embodiments, the refrigerant circulation system further comprises a second throttling component 13 arranged between the flash evaporator 12 and the evaporator 1.

[0049] The refrigerant flows through the compressor 3, the condenser 4, the first throttling component 11, the flash evaporator 12, the second throttling component 13 and the evaporator 1 in sequence in the refrigerant circulation process, and the refrigerant evaporated in the evaporator 1 returns to the suction port of the compressor 3 for compression again.

[0050] In some embodiments, the oil separator 2 comprises a shell-and-tube heat exchanger, the tube side of the shell-and-tube heat exchanger is the first refrigerant flow channel, and the shell side of the shell-and-tube heat exchanger is the second refrigerant flow channel. The shell-and-tube heat exchanger has the characteristics of simple structure, low cost and high heat exchange efficiency, and thus can effectively separate the lubricating oil in the refrigerant.

[0051] In the present embodiment, the separation process of the oil and the refrigerant in the shell-and-tube oil separator 2 is implemented as follows:

[0052] The shell-and-tube oil separator 2 is arranged at the bottom of the evaporator 1 by means of support welding, the shell side of the shell-and-tube oil separator 2 is connected to the bottom and the top of the evaporator 1 through pipelines respectively, and a large amount of oil-containing refrigerant at the same liquid level is taken from the evaporator 1 without any other power source by means of gravity and the principle of a communicating vessel.

[0053] The same liquid level means that the liquid level in the evaporator 1 is consistent with the liquid level in the shell-and-tube oil separator 2 by means of the principle of a communicating vessel. The high-temperature gaseous refrigerant taken from the exhaust port of the compressor 3 is at the tube side, and the temperature of the refrigerant at the exhaust port is the highest temperature in the entire unit, i.e. the exhaust temperature. The temperature of the oil-containing refrigerant from the evaporator is the lowest temperature in the entire unit, i.e. the evaporation temperature. The two are subjected to rapid and efficient heat exchange in the shell-and-tube oil separator. The oil-containing refrigerant at the shell side absorbs the heat of the compressor exhaust at the tube side, the refrigerant is rapidly evaporated to return to the evaporator, and the lubricating oil with a high boiling point is difficult to evaporate and thus is deposited at the bottom of the oil separator. The tube side adopts a 4-flow arrangement, and the pipeline enters from the bottom and exits from the top. Even when the unit is operated in the winter working condition with a low exhaust temperature, sufficient heat exchange can be achieved. After the high-temperature exhaust is subjected to sufficient heat exchange in the oil separator for 4 flows, the temperature is reduced, the separated liquid enters the evaporator 1 through the second throttling component 13 and still can produce refrigeration effect, and the separated gas enters the compressor to improve the system energy efficiency.

[0054] In some embodiments, the inlet of the first refrigerant flow channel is lower than the outlet of the first refrigerant flow channel, so that the refrigerant in the first refrigerant flow channel can be fully exchanged with the refrigerant in the second refrigerant flow channel, which is conducive to improving the heat exchange efficiency and the separation efficiency.

[0055] In some embodiments, the inlet of the second refrigerant flow channel is located upstream of the condenser 4 in the refrigerant flow direction, and the refrigerant compressed by the compressor 3 is directly delivered to the oil separator without condensation, the temperature of the introduced refrigerant is high, and the separation efficiency is improved.

[0056] The refrigerant circulation system further comprises an oil tank 5, an oil pump 6, and a first ejector 8. The oil pump 6 is in fluid connection with the oil tank 5 and is configured to deliver lubricating oil to the compressor 3. The first ejector 8 comprises an ejecting fluid inlet in fluid connection with the outlet of the oil pump 6, an ejected fluid inlet in fluid connection with the lubricating oil outlet of the oil separator 2, and an outlet in fluid connection with the oil tank 5. The separated lubricating oil is introduced by the oil pump 6 of the system, which is beneficial to improve the introduction pressure and add a new function to the original oil pump of the system, thereby simplifying the structure and reducing the cost.

[0057] The oil supply lubrication system of the compressor supplies lubricating oil from the oil tank 5 to the top of the compressor 3 by the oil pump 6. When the lubricating oil enters the compressor 3 to lubricate the bearing, the lubricating oil directly contacts the refrigerant in the compressor 3, and the two are mixed to form oil-containing refrigerant, which enters the evaporator 1. In the evaporator 1, the oil-containing refrigerant contacts the heat exchange tube, which directly leads to poor heat exchange effect. The increase of the heat exchange temperature difference leads to the increase of the power consumption of the unit and the decrease of the performance. If the unit runs for a long time and the oil enters the evaporator 1, the oil level in the oil tank 5 will decrease, the pressure difference before and after the oil supply of the oil pump 6 will decrease, and the unit will be protected and stopped, which directly affects the normal use of the unit. In the embodiment, the lubricating oil in the evaporator 1 is separated by the oil separator 2 and is injected back to the oil tank 5.

[0058] In some embodiments, the refrigerant circulation system further comprises a second ejector 10. The second ejector 10 comprises an ejecting fluid inlet in fluid connection with the condenser 4, an ejected fluid inlet in fluid connection with the lubricating oil outlet of the oil separator 2, and an outlet in fluid connection with the oil tank 5. The separated lubricating oil is introduced by the high-pressure gas in the condenser of the system, which is beneficial to improve the introduction pressure.

[0059] The refrigerant circulation system further comprises a first electromagnetic valve 7, a second electromagnetic valve 9, and a controller. The first electromagnetic valve 7 is configured to control the opening and closing of the outlet of the oil pump 6 and the ejecting fluid inlet of the first ejector 8. The second electromagnetic valve 9 is configured to control the opening and closing of the condenser 4 and the ejecting fluid inlet of the second ejector 10.

[0060] The controller is signal connected with the first electromagnetic valve 7 and the second electromagnetic valve 9 respectively, and is configured to execute opening the first electromagnetic valve 7 and closing the second electromagnetic valve 9 in response to a pressure difference ΔP1 of the condensing pressure of the refrigerant in the condenser 4 and the evaporating pressure of the refrigerant in the evaporator 1 being less than a reference pressure difference ΔP, and / or execute closing the first electromagnetic valve 7 and opening the second electromagnetic valve 9 in response to the pressure difference ΔP1 of the condensing pressure of the refrigerant in the condenser 4 and the evaporating pressure of the refrigerant in the evaporator 1 being greater than the reference pressure difference ΔP by a predetermined value.

[0061] In the embodiment, in order to guarantee the oil return reliability and improve the oil return efficiency, different oil return modes are realized by the electromagnetic valve control under different working conditions. Under the low pressure difference working condition, the oil pump outlet high pressure oil is used as the power source of the injection, the lubricating oil in the oil separator is directly injected into the oil tank by the oil pump, and the oil return reliability under the low pressure difference working condition is guaranteed. Under the high pressure difference working condition, the high temperature and high pressure condensing gas is used as the power source of the injection, and the lubricating oil in the oil separator is injected, and the oil return efficiency is improved.

[0062] The refrigerant circulation system further comprises a first pressure sensor for detecting the oil pressure of the oil tank 5 and a second pressure sensor for detecting the oil pressure of the lubricating oil output by the oil pump 6. The controller is signal connected with the first pressure sensor and the second pressure sensor respectively, and takes the pressure difference detected by the second pressure sensor and the first pressure sensor as the reference pressure difference ΔP.

[0063] In the embodiment, different oil return routes are switched under different working conditions, the oil return reliability of the unit is guaranteed, and the oil return efficiency is greatly improved.

[0064] In some embodiments, the lubricating oil outlet is located at the middle part of the first refrigerant flow channel in height. The oil outlet (lubricating oil outlet) of the oil separator should not be set too high or too low. If the liquid level of the evaporator and the oil separator is not full, the oil outlet is too high, and the oil cannot be taken. If the oil-containing refrigerant is too low, the oil-containing refrigerant cannot be heated by the high-temperature exhaust pipe in time and is taken away instantly.

[0065] Specifically, the oil outlet is preferably arranged at the height position of the middle row of the 4-row tube bundle. The heat exchange tube is designed at the middle position, because when the oil-containing refrigerant enters the oil separator from the bottom, the refrigerant evaporates quickly under a large temperature difference, and the liquid accumulated at the middle tube bundle height position is all lubricating oil with a higher boiling point.

[0066] The injection route is divided into two kinds according to the difference between the condensing and evaporating pressure of the unit, and the corresponding injection route is switched by the opening and closing of the electromagnetic valve. When the unit is running under low pressure difference condition, if the traditional single mode is still used, the gas from the condenser 4 is taken as the main injection fluid. At this time, the condensing pressure is close to the evaporating pressure, and the ejector is basically ineffective due to the lack of pressure difference driving, which leads to difficulty in oil return. At this time, the pressure sensor can detect the oil tank pressure, the oil supply pressure after the oil pump, the evaporating pressure of the evaporator, and the condensing pressure of the condenser.

[0067] When the condensing and evaporating pressure difference ΔP1 of the unit is detected to be less than the oil pump outlet oil supply pressure and the oil tank pressure difference ΔP, it is determined that the unit is in low pressure difference condition. The second electromagnetic valve 9 is closed, the first electromagnetic valve 7 is opened, and the unit starts the low pressure difference injection oil return mode. The oil supply outlet after the oil pump is divided into two paths. One path remains the original route to supply oil to the compressor high oil tank, and the other path is to supply oil as the main injection flow into the 8-liquid state injector to inject the purified lubricating oil from the oil separator back to the oil tank. When the condensing and evaporating pressure difference ΔP1 of the unit is detected to be greater than the oil pump outlet oil supply pressure and the oil tank pressure difference ΔP+50kpa, it is determined that the unit exits the low pressure difference condition. The second electromagnetic valve 9 is opened, the first electromagnetic valve 7 is closed, and the unit exits the low pressure difference injection oil return and starts the normal oil return mode. High pressure gaseous refrigerant is taken from the condenser as the main injection flow into the second injector 10 to inject the purified lubricating oil from the oil separator back to the oil tank 5. In this way, the pressure difference is detected to switch different oil return routes under different conditions, which ensures the reliability of the unit oil return and greatly improves the oil return efficiency. Thus, the oil return cycle of the two processes is completed.

[0068] In summary, the implementation of the embodiment achieves the following technical effects

[0069] 1. The shell and tube oil separator is provided, which uses gravity and the principle of communicating vessels to take a large amount of oil-containing cold medium of the same level from the evaporator without any other power source. The high-temperature exhaust gas flows through the tube, and the two fluids with the largest temperature difference in the water chilling unit are quickly heat exchanged in the heat exchanger to realize the separation of the refrigerant and the oil. At the same time, the tube of the shell and tube oil separator adopts 4-flow multi-flow arrangement, which can fully heat exchange and ensure the oil separation effect even when the condensing temperature is low in winter.

[0070] 2. To ensure the reliability of oil return and improve the oil return efficiency, different oil return modes are realized under different conditions by electromagnetic valve control. Under low pressure difference condition, the injection power source adopts high pressure oil supply outlet of the oil pump to inject the lubricating oil in the oil separator directly into the oil tank, which ensures the reliability of oil return under low pressure difference condition. Under high pressure difference condition, the injection power source adopts high temperature and high pressure condensing gas to inject the lubricating oil in the oil separator, which improves the oil return efficiency.

[0071] According to another aspect of the present application, there is also provided an air conditioning system including the above-described refrigerant circulation system.

[0072] The above merely shows exemplary embodiments of the present application, and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A refrigerant circulating system characterized by comprising: Comprise: a compressor (3); a condenser (4) fluidly connected to a discharge port of the compressor (3); a first throttling member (11) fluidly connected to the condenser (4) and configured to throttle refrigerant condensed by the condenser (4); an evaporator (1) including an inlet fluidly connected to the first throttling member (11) to introduce refrigerant throttled by the first throttling member (11) and an outlet fluidly connected to a suction port of the compressor (3); an oil separator (2) including a first refrigerant flow passage fluidly connected to the evaporator (1), a second refrigerant flow passage configured to exchange heat with the first refrigerant flow passage and fluidly connected to the discharge port of the compressor (3), and a lubricating oil outlet communicating with the first refrigerant flow passage, an inlet of the second refrigerant flow passage is located upstream of the condenser (4) in a refrigerant flow direction, the refrigerant circulation system further comprises: an oil tank (5); an oil pump (6) fluidly connected to the oil tank (5) and configured to deliver lubricating oil to the compressor (3); a first ejector (8) including an ejecting fluid inlet fluidly connected to an outlet of the oil pump (6), a sucked fluid inlet fluidly connected to the lubricating oil outlet of the oil separator (2), and an outlet fluidly connected to the oil tank (5), the refrigerant circulation system further comprises a second ejector (10) including an ejecting fluid inlet fluidly connected to the condenser (4), a sucked fluid inlet fluidly connected to the lubricating oil outlet of the oil separator (2), and an outlet fluidly connected to the oil tank (5), the refrigerant circulation system further comprises: a first electromagnetic valve (7) configured to control opening and closing of the outlet of the oil pump (6) and the ejecting fluid inlet of the first ejector (8); a second electromagnetic valve (9) configured to control opening and closing of the condenser (4) and the second ejector (10) and the ejecting fluid inlet of the second ejector (10); a controller signal connected to the first electromagnetic valve (7) and the second electromagnetic valve (9), respectively, and configured to perform opening the first electromagnetic valve (7) and closing the second electromagnetic valve (9) in response to a pressure difference ΔP1 of a condensing pressure of refrigerant in the condenser (4) and an evaporating pressure of refrigerant in the evaporator (1) being less than a reference pressure difference ΔP, and / or perform closing the first electromagnetic valve (7) and opening the second electromagnetic valve (9) in response to the pressure difference ΔP1 of the condensing pressure of refrigerant in the condenser (4) and the evaporating pressure of refrigerant in the evaporator (1) being greater than the reference pressure difference ΔP by a predetermined value.

2. The refrigerant cycle system according to claim 1, characterized by The height of the oil separator (2) relative to the evaporator (1) is configured such that liquid in the evaporator (1) can flow to the first refrigerant flow passage of the oil separator (2) under the action of gravity.

3. The refrigerant cycle system according to claim 1 or 2, characterized by The oil separator (2) is not higher than the bottom of the evaporator (1).

4. The refrigerant circulation system according to claim 1, wherein The inlet of the first refrigerant flow channel is fluidly connected with the evaporator (1), and the outlet of the first refrigerant flow channel is fluidly connected with the evaporator (1); and / or The inlet of the second refrigerant flow channel is fluidly connected with the exhaust port of the compressor (3), and the outlet of the second refrigerant flow channel is fluidly connected with the suction port of the compressor (3).

5. The refrigerant cycle system according to claim 1 or 4, characterized by Further comprising a flasher (12), the flasher (12) comprising an inlet fluidly connected with the condenser (4), a liquid refrigerant outlet fluidly connected with the evaporator (1), and a gaseous refrigerant outlet fluidly connected with the charge port of the compressor (3), and the outlet of the second refrigerant flow channel is fluidly connected with the flasher (12).

6. The refrigerant cycle system according to claim 1, characterized by The oil separator (2) comprises a shell-and-tube heat exchanger, the tube side of the shell-and-tube heat exchanger being the first refrigerant flow channel, and the shell side of the shell-and-tube heat exchanger being the second refrigerant flow channel.

7. The refrigerant cycle system according to claim 1, characterized by The inlet of the first refrigerant flow channel is lower than the outlet of the first refrigerant flow channel.

8. The refrigerant cycle system according to claim 1, characterized by Further comprising a first pressure sensor for detecting the oil pressure of the oil tank (5) and a second pressure sensor for detecting the oil pressure of the lubricating oil output by the oil pump (6), the controller is signal connected with the first pressure sensor and the second pressure sensor respectively, and the difference between the pressures detected by the second pressure sensor and the first pressure sensor is taken as the reference differential pressure ΔP.

9. The refrigerant cycle system according to claim 1, characterized by, The lubricating oil outlet is located at the middle part of the first refrigerant flow channel in height.

10. An air conditioning system characterized by, The refrigerant circulation system according to any one of claims 1 to 9. The refrigerant circulation system according to any one of claims 1 to 9.

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