Heat exchanger, refrigeration system and control device

Abstract

This application provides a heat exchanger (1) capable of recovering lubricating oil according to liquid level changes using the heat exchanger (1) as an evaporator. The heat exchanger (1) includes a heat exchanger shell (101), a refrigerant inlet (102), a refrigerant outlet (103), a heat exchange tube bundle (104), a first lubricating oil return port (105) opened on a side surface of the heat exchanger shell (101), and a second lubricating oil return port (106) opened on the side surface of the heat exchanger shell (101) and closer to the top of the heat exchanger shell (101) than the first lubricating oil return port (105). By arranging the first lubricating oil return port (105) and the second lubricating oil return port (106) at different positions in a height direction of the heat exchanger shell (101), when the working condition of the heat exchanger (101) changes, the lubricating oil return port (105,106) matched with a liquid level in a heat exchanger shell cavity (101a) is switched, thereby avoiding the problem that an operation of a compressor is affected due to no oil recovery that may occur when the liquid level in the heat exchanger shell (101) fluctuates excessively due to only using one fixed lubricating oil return port.

Description

BACKGROUND

[0001] This invention relates to the technical field of refrigeration / cooling equipment, in particular to a heat exchanger capable of recovering lubricating oil according to liquid level changes, a refrigeration system using the heat exchanger as an evaporator, and a control device for controlling an operation of the refrigeration system.

[0002] For a refrigeration system, lubricating oil is usually required to reduce friction between rotary parts of a compressor. When a refrigerant participates in a refrigeration cycle in the refrigeration system, part of the lubricating oil in the compressor may be mixed with the refrigerant to enter the refrigeration cycle. When the lubricating oil flows into a heat exchanger as an evaporator with a liquid refrigerant, the refrigerant in a heat exchanger shell cavity exchanges heat with a heat exchange medium in a heat exchange tube bundle, so that the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant, the gaseous refrigerant flows out of the heat exchanger through a refrigerant outlet arranged at the top of the heat exchanger, and part of the lubricating oil that is mixed with the liquid refrigerant to enter the heat exchanger remains in the heat exchanger shell cavity.

[0003] In the prior art, a lubricating oil return port is provided on a side surface of a heat exchanger shell, so that the lubricating oil in the heat exchanger flows out of the heat exchanger through the lubricating oil return port, thereby avoiding the problem that part of the lubricating oil remains in the heat exchanger, resulting in the reduction of the lubricating oil in the compressor or the influence on the heat exchange efficiency in the heat exchanger.

[0004] However, when a working condition, a load and the like of the heat exchanger change, a flow rate of the refrigerant flowing into the heat exchanger, an evaporation rate inside the heat exchanger and the like change correspondingly, which may affect a liquid level inside the heat exchanger. When a current liquid level inside the heat exchanger is below or above the lubricating oil return port, the lubricating oil, which is mainly located at the liquid level of the refrigerant in the heat exchanger, may not be recovered in time, which affects the operation of the compressor.SUMMARY

[0005] The invention aims to provide a heat exchanger that can recover lubricating oil according to liquid level changes, so as to at least solve or alleviate some of the problems existing in the prior art.

[0006] A first aspect of the invention provides a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system, the heat exchanger including: a heat exchanger shell enclosing a heat exchanger shell cavity; a refrigerant inlet opened in the heat exchanger shell and communicating with the heat exchanger shell cavity; a refrigerant outlet opened at the top of the heat exchanger shell and communicating with the heat exchanger shell cavity; a heat exchange tube bundle arranged in the heat exchanger shell cavity and configured to allow a heat exchange medium for heat exchange of the refrigerant in the heat exchanger shell cavity to circulate therethrough, a first lubricating oil return port opened on a side surface of the heat exchanger shell and communicating with the heat exchanger shell cavity; and a second lubricating oil return port opened on the side surface of the heat exchanger shell and closer to the top of the heat exchanger shell than the first lubricating oil return port.

[0007] In one or more embodiments, a distance L between the first lubricating oil return port and the second lubricating oil return port in a height direction of the side surface of the heat exchanger shell and a height H of the side surface of the heat exchanger shell satisfy a numerical relationship 1 10 H < L < 1 2 H.

[0008] In one or more embodiments, the first lubricating oil return port and the second lubricating oil return port are arranged at different positions in a direction of the heat exchange tube bundle.

[0009] In one or more embodiments, the first lubricating oil return port and the second lubricating oil return port are arranged at the same position in a height direction of the side surface of the heat exchanger shell.

[0010] A second aspect of the invention provides a refrigeration system including: a compressor having a suction-side primary suction chamber, a condenser, and an evaporator, which are connected in sequence through a refrigerant pipeline, in which the evaporator is the heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to any one of the above technical solutions. The refrigeration system further includes: a first ejector having an input end in communication with the first lubricating oil return port and a power end in communication with an exhaust side of the compressor; and a second ejector having an input end in communication with the second lubricating oil return port and a power end in communication with the exhaust side of the compressor.

[0011] In one or more embodiments, an output end of the first ejector communicates with a suction side of the compressor, and an output end of the second ejector communicates with a suction side of the compressor.

[0012] In one or more embodiments, the refrigeration system further includes: a lubricating oil tank in communication with an output end of the first ejector and an output end of the second ejector; and a bypass pipeline having one end connected to the lubricating oil tank and the other end connected to the suction-side primary suction chamber of the compressor.

[0013] In one or more embodiments, the refrigeration system further includes: a four-way valve in communication with the first lubricating oil return port, the second lubricating oil return port, the input end of the first ejector and the input end of the second ejector separately, and configured to enable the first lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector, and the second lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector.

[0014] In one or more embodiments, the refrigeration system further includes: a first solenoid valve arranged in a pipeline in communication with the power end of the first ejector; and a second solenoid valve arranged in a pipeline in communication with the power end of the second ejector.

[0015] In one or more embodiments, the refrigeration system further includes: a lubricating oil pump arranged inside the lubricating oil tank and configured to allow the lubricating oil tank to communicate with an oil supply pipeline on a lubricating oil inlet side of the compressor.

[0016] In one or more embodiments, the refrigeration system further includes: a third ejector having an input end in communication with the suction-side primary suction chamber of the compressor and a power end in communication with an exhaust side of the compressor, the output end being in communication with the lubricating oil tank.

[0017] In one or more embodiments, the refrigeration system further includes: a lubricating oil heater arranged in the lubricating oil tank.

[0018] A third aspect of the invention provides a control device for regulating and controlling the refrigeration system according to the above technical solution, the control device including: an evaporator liquid level detection module configured to detect and record a current liquid level of the evaporator in real time; a four-way valve switching module configured to enable, according to the current liquid level of the evaporator detected by the evaporator liquid level detection module, one end of the four-way valve to be connected to the first lubricating oil return port or the second lubricating oil return port, and the other end of the four-way valve to be connected to the first ejector or the second ejector; and a solenoid valve control module configured to control the first solenoid valve to open and the second solenoid valve to close when the four-way valve is switched to communicate with the first ejector, and control the second solenoid valve to open and the first solenoid valve to close when the four-way valve is switched to communicate with the second ejector.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0019] Fig. 1 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a first embodiment. Fig. 2 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a second embodiment of. Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a third embodiment. Fig. 4 is a schematic diagram of modules of a refrigeration system according to a fourth embodiment. Fig. 5 is a schematic diagram of modules of a refrigeration system according to the fourth embodiment. Fig. 6 is a schematic diagram of modules of a refrigeration system according to a fifth embodiment. Fig. 7 is a schematic diagram of modules of a control device according to a sixth embodiment.

[0020] Reference numerals: heat exchanger 1, heat exchanger shell 101, heat exchanger shell cavity 101a, refrigerant inlet 102, refrigerant outlet 103, heat exchange tube bundle 104, heat exchange medium inlet 1041, heat exchange medium outlet 1042, first lubricating oil return port 105, second lubricating oil return port 106, refrigeration system 2, refrigerant pipeline 201, compressor 202, suction-side primary suction chamber 2021, condenser 203, evaporator 204, first ejector 205, second ejector 206, four-way valve 207, first solenoid valve 208, second solenoid valve 209, lubricating oil tank 210, bypass pipeline 2101, lubricating oil inlet 2102, lubricating oil pump 211, lubricating oil heater 212, third ejector 213, third solenoid valve 214, control device 3, evaporator liquid level detection module 31, four-way valve switching module 32, and solenoid valve control module 33.DETAILED DESCRIPTION OF THE DISCLOSURE

[0021] It should be noted that working principles, features, advantages, and the like of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system will be explained below by way of embodiments. However, it should be understood that all descriptions are only given for exemplification and therefore these embodiments should not be understood as forming any limitation on the invention.

[0022] In addition, for any single technical feature described or implicit in some embodiments mentioned herein, or any single technical feature shown or implicit in the drawings, the invention still allows any combination or deletion between these technical features (or their equivalents) without any technical obstacles, thereby obtaining more other embodiments of the invention that may not be directly mentioned herein, but that are nevertheless within the scope of the invention defined by the claims.

[0023] Fig. 1 is a schematic structural diagram of a heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a first embodiment. Referring to Fig. 1, the heat exchanger 1 includes a heat exchanger shell 101, a refrigerant inlet 102, a refrigerant outlet 103, a heat exchange tube bundle 104, a first lubricating oil return port 105, and a second lubricating oil return port 106.

[0024] As shown in Fig. 1, the heat exchanger shell 101 encloses a heat exchanger shell cavity 101a, the refrigerant inlet 102 is opened at the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a, and the refrigerant outlet 103 is opened at the top of the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a. The heat exchange tube bundle 104 is further arranged in the heat exchanger shell cavity 101a, and an external heat exchange medium enters the heat exchange tube bundle 104 to exchange heat with a refrigerant circulating in the heat exchanger shell cavity 101a. Specifically, a liquid refrigerant mixed with lubricating oil flows into the interior of the heat exchanger shell cavity 101a through the refrigerant inlet 102, exchanges heat with the heat exchange medium such as hot water in the heat exchange tube bundle 104, so that the temperature of the liquid refrigerant increases, the liquid refrigerant evaporates into a gaseous state, and the evaporated refrigerant gas flows out of the heat exchanger 1 through the refrigerant outlet 103 arranged at the top of the heat exchanger shell 101.

[0025] The heat exchanger shell 101 is further provided with the first lubricating oil return port 105 and the second lubricating oil return port 106, the first lubricating oil return port 105 and the second lubricating oil return port 106 are both opened on a side surface of the heat exchanger shell 101, and the second lubricating oil return port 106 is closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105, that is, closer to the refrigerant outlet 103.

[0026] When a flow rate of the refrigerant flowing into the heat exchanger 1 decreases, or the flow rate of the refrigerant flowing into the heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into the heat exchanger 1 increases, an evaporation rate of the liquid refrigerant is relatively high, that is, when a liquid level of the liquid refrigerant in the heat exchanger 1 is at a lower position, the lubricating oil mixed with the liquid refrigerant and floating on a surface of the liquid refrigerant may flow out of the heat exchanger 1 through the first lubricating oil return port 105 (that is, the lubricating oil return port located at the lower position on the side surface of the heat exchanger shell 101) opened at the side surface of the heat exchanger shell 101.

[0027] When the flow rate of the refrigerant flowing into the heat exchanger 1 increases, or the flow rate of the refrigerant flowing into the heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into the heat exchanger 1 decreases, the evaporation rate of the liquid refrigerant is relatively low, which may cause the liquid level of the liquid refrigerant in the heat exchanger 1 to be at a higher position, so that at this time, the lubricating oil mixed with the liquid refrigerant and floating on a liquid level surface of the liquid refrigerant may flow out of the heat exchanger 1 through the second lubricating oil return port 106 opened on the side surface of the heat exchanger shell 101 and closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105.

[0028] According to the above embodiment, in the heat exchanger, the first lubricating oil return port 105 or the second lubricating oil return port 106 at different heights may be selected according to different liquid levels of the refrigerant in the heat exchanger shell cavity 101a, so that the lubricating oil return port matches the liquid level of the refrigerant in the heat exchanger shell cavity 101a, thereby avoiding the problem that when a working condition of the heat exchanger 1 changes, that is, when the liquid level of the refrigerant in the heat exchanger shell cavity 101a changes, the liquid level of the refrigerant does not match the height of the lubricating oil return port, and consequently, the lubricating oil mainly near the liquid level surface of the refrigerant cannot be recovered in time through the lubricating oil return port, affecting an operation of the refrigeration system.

[0029] It should be noted that although the refrigerant inlet 102 and the refrigerant outlet 103 of the heat exchanger 1 shown in Fig. 1 are staggered, the invention is not limited thereto, and the arrangement of the refrigerant inlet 102 and the refrigerant outlet 103 flexibly designed according to different operating conditions, process designs, and the like of the heat exchanger 1 should be included in the protection scope of the invention.

[0030] As a preferred embodiment, a distance L between the first lubricating oil return port 105 and the second lubricating oil return port 106 in a height direction of the side surface of the heat exchanger shell 101 and a height H of the side surface of the heat exchanger shell 101 satisfy a numerical relationship 1 10 H < L < 1 2 H.

[0031] Through the above embodiment, the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 is set to L > 1 10 H, which avoids the problem that when the liquid level of the refrigerant inside the heat exchanger shell cavity 101a changes greatly, the excessively small distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 results in an inability to match the liquid level change inside the heat exchanger shell cavity 101a even if the first lubricating oil return port 105 or the second lubricating oil return port 106 is switched. At the same time, the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 is set to L < 1 2 H, which avoids the problem that when the liquid level of the refrigerant inside the heat exchanger shell cavity 101a changes greatly and still does not drop (or rise) to reach the first lubricating oil return port 105 (or second lubricating oil return port 106), the excessively large distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 causes the connected lubricating oil return port to be unable to match the liquid level change of the refrigerant in the heat exchanger shell cavity 101a in time.

[0032] It should be noted that although the first lubricating oil return port 105 and the second lubricating oil return port 106 are described as an example in some embodiments, the invention is not limited thereto, and the arrangement of adding more lubricating oil return ports according to different operating conditions of the refrigeration system 2, models and parameters of the heat exchanger 1, and the like are also included in the protection scope of the invention.

[0033] Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a second embodiment and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0034] Fig. 2 is a schematic structural diagram of the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the second embodiment. Referring to Fig. 2, different from the heat exchanger 1 according to the first embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the second embodiment are arranged at different positions along an extension direction of the heat exchange tube bundle 104.

[0035] The refrigerant exchanges heat with a heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger shell cavity 101a, and the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, in a flow direction of the heat exchange medium, a liquid refrigerant close to a heat exchange medium inlet 1041 sufficiently evaporates into a gaseous refrigerant upon absorbing heat, and thus a liquid level of the liquid refrigerant is relatively low, while a liquid refrigerant close to a heat exchange medium outlet 1042 does not evaporate sufficiently into a gaseous refrigerant upon absorbing heat due to a small temperature difference, and thus a liquid level of the liquid refrigerant is relatively high. Thus, there is a difference in the liquid level of the liquid refrigerant at different positions along the extension direction of the heat exchange tube bundle 104 in the heat exchanger 1. Generally speaking, the liquid level of the liquid refrigerant close to the heat exchange medium inlet 1041 is relatively low, and the liquid level of the liquid refrigerant close to the heat exchange medium outlet 1042 is relatively high. In addition, as the liquid refrigerant evaporates, the liquid level of the liquid refrigerant may also fluctuate inside the heat exchanger shell cavity 101a along the extension direction of the heat exchange tube bundle 104.

[0036] Through the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 are arranged at different positions along the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105. Preferably, the first lubricating oil return port 105 is arranged at a position close to the heat exchange medium inlet 1041 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged at a position close to the heat exchange medium outlet 1042 in the extension direction of the heat exchange tube bundle 104. The second lubricating oil return port 106 closer to the top of the heat exchanger shell 101 corresponds to a position close to the heat exchange medium outlet 1042 with a higher liquid level in the heat exchanger shell cavity 101a, and the first lubricating oil return port 105 corresponds to a position close to the heat exchange medium inlet 1041 with a lower liquid level in the heat exchanger shell cavity 101a. This avoids the problem that when only one fixed lubricating oil return port is used, the oil return efficiency may be affected due to uneven distribution of the lubricating oil within the heat exchanger 1 or its accumulation primarily on one side.

[0037] It should be noted that although the first lubricating oil return port 105 and the second lubricating oil return port 106 are provided at different positions in the extension direction of the heat exchange tube bundle 104 as an example for description in some embodiments, the invention is not limited thereto, and the manner of providing a plurality of lubricating oil return ports according to the extension direction of the heat exchange tube bundle 104 of the heat exchanger 1 and different liquid levels are also included in the protection scope of the invention.

[0038] Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a third embodiment and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0039] Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to the third embodiment. Referring to Fig. 3, different from the heat exchanger 1 according to the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the third embodiment are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101. Further preferably, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged farther from the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104.

[0040] The refrigerant exchanges heat with the heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger shell cavity 101a, and the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, in a working state, the refrigerant is consistently in a localized boiling and vaporization state in the heat exchanger shell cavity 101a, and violent vaporization occurs on both the inside and the surface of the refrigerant liquid, which may cause the liquid level of the refrigerant in the heat exchanger shell cavity 101a to fluctuate.

[0041] When the liquid level of the refrigerant inside the heat exchanger shell cavity 101a fluctuates greatly due to the boiling and vaporization state, for example, a liquid level of a refrigerant close to (or away from) the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104 rises to the height of the first lubricating oil return port 105 (or second lubricating oil return port 106), and at this time, the lubricating oil mixed with the liquid refrigerant and floating on the liquid level surface of the liquid refrigerant may flow out of the heat exchanger 1 through the first lubricating oil return port 105 (or second lubricating oil return port 106).

[0042] The first lubricating oil return port 105 and the second lubricating oil return port 106 are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged farther from the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, so that the lubricating oil mixed with the liquid refrigerant and floating on the liquid level surface of the liquid refrigerant can flow out of the heat exchanger 1 for recovery through the first lubricating oil return port 105 or the second lubricating oil return port 106 matching the liquid level in the heat exchanger shell cavity 101a according to the liquid level in the heat exchanger shell cavity 101a, especially the liquid level fluctuation caused by the refrigerant being in the boiling state. Through the above embodiment, even if the liquid level in the heat exchanger shell cavity 101a frequently fluctuates, it is still possible to allow the lubricating oil to flow out through either the first lubricating oil return port 105 or the second lubricating oil return port 106, depending on which one matches the current liquid level, thereby improving the oil return efficiency of the refrigeration system and the operation stability of the refrigeration system.

[0043] It should be noted that, in some embodiments, specific positions of the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 are not limited, and the form in which different specific positions of the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 are set according to parameters such as an operating condition of the refrigeration system, a refrigerant charge amount in the refrigeration system, and a model of the heat exchanger 1.

[0044] A fourth embodiment provides a refrigeration system 2 including a compressor 202, a condenser 203 and an evaporator 204, which are connected in sequence through a refrigerant pipeline. The compressor 202 has a suction-side primary suction chamber 2021, and the evaporator 204 is the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiments.

[0045] Fig. 4 is a schematic diagram of modules of a refrigeration system according to a fourth embodiment. Referring to Fig. 4, the refrigeration system 2 according to the fourth embodiment further includes a first ejector 205, a second ejector 206, a lubricating oil tank 210, a bypass pipeline 2101, a lubricating oil inlet 2102, and a lubricating oil pump 211.

[0046] The ejector has an input end, an output end and a power end, and the input end is connected to a nozzle of the ejector. As shown in Fig. 4, an input end of the first ejector 205 communicates with the first lubricating oil return port 105, a power end of the first ejector 205 communicates with an exhaust side of the compressor 202, an input end of the second ejector 206 communicates with the second lubricating oil return port 106, a power end of the second ejector 206 communicates with the exhaust side of the compressor 202, and an output end of the first ejector 205 and an output end of the second ejector 206 both communicate with a suction side of the compressor 202.

[0047] The refrigeration system 2 according to the fourth embodiment further includes the lubricating oil tank 210 arranged at a lowest part of the refrigeration system 2, one end of the bypass pipeline 2101 is connected to the lubricating oil tank 210, the other end of the bypass pipeline 2101 is connected to the suction-side primary suction chamber 2021 of the compressor, lubricating oil delivered to the suction-side primary suction chamber 2021 of the compressor through the output end of the first ejector 205 and the output end of the second ejector 206 flows to the lubricating oil tank 210 through the bypass pipeline 2021 under the action of gravity.

[0048] The lubricating oil tank 210 is further provided with the lubricating oil pump 211, one end of the oil supply pipeline where the lubricating oil pump 211 is located communicates with the lubricating oil tank 210, and the other end of the oil supply pipeline communicates with the lubricating oil inlet 2102 of the compressor 202. When it is detected that the amount of lubricating oil in the compressor 202 is reduced or lower than the demand amount, the lubricating oil pump 211 provides a driving force for the lubricating oil in the lubricating oil tank 210, so that the lubricating oil stored in the lubricating oil tank 210 is conveyed to the compressor 202, thereby preventing the operation of the compressor 202 from being affected by insufficient lubricating oil.

[0049] Through the above embodiment, a high-pressure gaseous refrigerant discharged by the compressor 202 flows into the first ejector 205 or the second ejector 206 through the power end, and flows out at a faster speed through a nozzle of the first ejector 205 or the second ejector 206. The downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts the lubricating oil (possibly including part of the liquid or gaseous refrigerant) flowing out of the evaporator 204 from the first lubricating oil return port 105 or the second lubricating oil return port 106 in communication with the input end of the first ejector 205 or the second ejector 206. The lubricating oil passing through the first ejector 205 or the second ejector 206 is mixed with the refrigerant and then flows into the suction-side primary suction chamber 2021 of the compressor 202 through the output end of the first ejector 205 or the second ejector 206, so that the lubricating oil is temporarily stored at the bottom of the suction-side primary suction chamber 2021 of the compressor 202. Under the action of gravity, the lubricating oil temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 flows to the lubricating oil tank 210 through the bypass pipeline 2021 with one end connected to the suction-side primary suction chamber 2021 of the compressor 202 and the other end connected to the lubricating oil tank 210, thereby completing the oil recovery of the lubricating oil while achieving the pressure balance in the refrigeration system 2.

[0050] At the same time, a part of the high-temperature and high-pressure gaseous refrigerant flowing out of the exhaust side of the compressor 202 also returns to the suction side of the compressor 202 after passing through the first ejector 205 or the second ejector 206, and is mixed with the gaseous refrigerant flowing out of the evaporator 204, so that the pressure and temperature of the refrigerant flowing into the compressor 202 are increased, and the working efficiency of the compressor 202 is improved.

[0051] In this way, an air pressure difference generated when the high-pressure refrigerant discharged from the exhaust side of the compressor 202 flows through the nozzles of the first ejector 205 and the second ejector 206 provides a drainage force for the lubricating oil to flow to the first ejector 205 or the second ejector 206, thereby improving the recovery efficiency of the lubricating oil.

[0052] As a preferred embodiment, a connection pipeline between the input end of the first ejector 205 and the first lubricating oil return port 105 and a connection pipeline between the input end of the second ejector 206 and the second lubricating oil return port 106 are further provided with a four-way valve 207, and four valve ports of the four-way valve 207 can communicate with the input end of the first ejector 205, the first lubricating oil return port 105, the input end of the second ejector 206 and the second lubricating oil return port 106, respectively.

[0053] Therefore, by adjusting the switching of the four-way valve 207, the first lubricating oil return port 105 can be controlled to communicate with the input end of the first ejector 205 or the input end of the second ejector 206, or the second lubricating oil return port 106 can be controlled to communicate with the input end of the first ejector 205 or the input end of the second ejector 206.

[0054] Through the above embodiment, when the lubricating oil from the evaporator 204 is recovered through the first lubricating oil return port 105 (or second lubricating oil return port 106), the four-way valve can be switched to communicate with the matching first ejector 205 or second ejector 206 according to the conditions such as a flow rate and pressure of the fluid flowing out of the evaporator 204 from the first lubricating oil return port 105 (or second lubricating oil return port 106), so that the working efficiency and reliability of the ejector are improved, and the possibility is also reduced that the use of an ejector that does not match the actual flow rate and pressure of the fluid results in a mismatch between a suction force of the fluid flowing out of the evaporator 204 and the flow rate, resulting in an inadequate drainage of the lubricating oil flowing out of the first lubricating oil return port 105 (or second lubricating oil return port 106), thereby reducing the oil recovery efficiency.

[0055] As a preferred embodiment, according to the liquid level change inside the evaporator 204, the four-way valve 207 is controlled to simultaneously connect the first lubricating oil return port 105 with the first ejector 205 and the second ejector 206 or simultaneously connect the second lubricating oil return port 106 with the first ejector 205 and the second ejector 206, that is, the first ejector 205 and the second ejector 206 always work simultaneously, and the four-way valve 207 can be switched to communicate with the matching first lubricating oil return port 105 or second lubricating oil return port 106 according to the liquid level change inside the evaporator 204.

[0056] Through the above embodiment, when the flow rate of the fluid flowing out of the first lubricating oil return port 105 (or second lubricating oil return port 106) is large, the four-way valve 207 communicates with the first ejector 205 and the second ejector 206 simultaneously, so that the first ejector 205 and the second ejector 206 always work simultaneously, and the four-way valve 207 can be switched to communicate with the matching first lubricating oil return port 105 or second lubricating oil return port 106 according to the adjustment of the liquid level in the evaporator 204, thereby improving the oil recovery efficiency and reliability of the refrigeration system.

[0057] Fig. 5 is a schematic diagram of modules of a refrigeration system according to the fourth embodiment. Referring to Fig. 5, further preferably, a first solenoid valve 208 is further arranged on the pipeline in communication with the power end of the first ejector 205, and a second solenoid valve 209 is further arranged on the pipeline in communication with the power end of the second ejector 206.

[0058] When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or second lubricating oil return port 106) to the first ejector 205, the first solenoid valve 208 is controlled to open and the second solenoid valve 209 is controlled to close. At this time, a small part of the refrigerant carrying the lubricating oil flowing out of the compressor 202 flows into the first ejector 205 through the first solenoid valve 208, and a main part thereof flows into the condenser 203 to continue a refrigeration cycle. When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or second lubricating oil return port 106) to the second ejector 206, the first solenoid valve 208 is controlled to close, and the second solenoid valve 209 is controlled to open. At this time, a small part of the refrigerant carrying the lubricating oil flowing out of the compressor 202 flows into the second ejector 206 through the second solenoid valve 209, and a main part thereof flows into the condenser 203 to continue the refrigeration cycle.

[0059] By switching the four-way valve 207 and controlling the opening and closing of the first solenoid valve 208 or the second solenoid valve 209, the first ejector 205 or the second ejector 206 is switched to be connected according to the working conditions such as the flow rate and pressure of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106), thereby improving the oil recovery efficiency of the refrigeration system 2, and also avoiding the problem that the high-temperature and high-pressure gaseous refrigerant flowing out of the compressor 202 returns to the suction side of the compressor 202 through the first ejector 205 and the second ejector 206 simultaneously, thereby reducing the refrigerant participating in the refrigeration cycle and lowering the heat exchange efficiency. At the same time, the first solenoid valve 208 or the second solenoid valve 209 corresponding to the first ejector 205 or the second ejector 206 that does not communicate with the first lubricating oil return port 105 (or second lubricating oil return port 106) is controlled to close, thereby solving the problem that it is difficult to balance a pressure difference inside the unconnected first ejector 205 or second ejector 206, and improving the reliability of the refrigeration system 2.

[0060] Although some embodiments are described in the form of the first ejector 205, the second ejector 206 and the corresponding first solenoid valve 208 and second solenoid valve 209, the invention is not limited thereto. The form of arranging more ejectors and corresponding solenoid valves according to the operating conditions of the refrigeration system 2, the model parameters of the evaporator 204, the model parameters of the ejector and the like are included in the protection scope of the invention.

[0061] Elements denoted by the same names and symbols as those in the refrigeration system 2 according to a fifth embodiment and the refrigeration system 2 according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0062] Fig. 6 is a schematic diagram of modules of the refrigeration system according to the fifth embodiment. Referring to Fig. 6, the refrigeration system 2 according to the fifth embodiment further includes a lubricating oil heater 212 arranged in the lubricating oil tank 210.

[0063] The refrigerant in the lubricating oil stored in the lubricating oil tank 210 is heated by the lubricating oil heater 212 arranged in the lubricating oil tank 210 to accelerate evaporation of the refrigerant, and the evaporated refrigerant returns to the suction-side primary suction chamber 2021 of the compressor 202 through the bypass pipeline 2101 to continue the refrigeration cycle, thereby avoiding the problem that the excessive refrigerant remaining in the lubricating oil tank 210 causes the temperature of the lubricating oil stored in the lubricating oil tank 210 to become too low, thereby affecting an lubrication effect.

[0064] Preferably, a third ejector 213 is further provided in a pipeline connecting the lubricating oil tank 210 and the output end of the first ejector 205 or the second ejector 206, and the third ejector 213 has an input end in communication with the suction-side primary suction chamber of the compressor, a power end in communication with the exhaust side of the compressor, and an output end communication with the lubricating oil tank.

[0065] Through the above embodiment, the high-pressure gaseous refrigerant discharged by the compressor 202 flows into the third ejector 213 through the power end, and flows out at a faster speed through a nozzle of the third ejector 213, and a downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts an oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 in communication with the input end of the third ejector 213. The oil-containing refrigerant passing through the third ejector 213 flows into the lubricating oil tank 210 through the output end of the third ejector 213, so that the bypass pipeline 2101 and the third ejector 213 cooperate to realize oil recovery of the lubricating oil, thereby improving the oil recovery efficiency.

[0066] Preferably, a third solenoid valve 214 is further provided in a pipeline connecting the power end of the third ejector 213 and the exhaust side of the compressor 202, and the opening and closing of the third solenoid valve 214 is controlled according to conditions such as the flow rate and pressure of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106). Specifically, when the flow rate of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106) is small, the third solenoid valve 214 is controlled to close. At this time, the third ejector 213 attracts the oil-containing refrigerant in the suction-side primary suction chamber 2021 of the compressor 202 by forming a bypass pipeline at the input end and the output end of the third ejector 213 under the action of gravity instead of forming the low-pressure area, and the oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 flows into the lubricating oil tank 210 through the input end and the output end of the third ejector 213 under the action of gravity. When the flow rate of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106) is large, the third solenoid valve 214 is controlled to open. At this time, the high-pressure gaseous refrigerant discharged from the compressor 202 flows into the third ejector 213 through the power end, and the downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts the oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 in communication with the input end of the third ejector 213, thereby improving the oil recovery efficiency.

[0067] A control device is further provided for regulating and controlling the refrigeration system 2. Fig. 7 is a schematic diagram of modules of a control device according to a sixth embodiment. Referring to Fig. 7, the sixth embodiment provides a control device 3 for regulating and controlling the refrigeration system 2 according to any one of the above embodiments, and the control device 3 includes an evaporator liquid level detection module 31, a four-way valve switching module 32, and a solenoid valve control module 33.

[0068] The evaporator liquid level detection module 31 detects and records a current liquid level of the evaporator 204 in real time. When the current liquid level detected by the evaporator liquid level detection module 31 is high, the four-way valve switching module 32 switches the four-way valve 207 to connect one end thereof to the second lubricating oil return port 106 closer to the top of the evaporator 204, so that the lubricating oil mixed with the liquid refrigerant and floating on the surface of the liquid refrigerant flows out of the evaporator 204 for recovery through the second lubricating oil return port 106. When the current liquid level detected by the evaporator liquid level detection module 31 is low, the four-way valve switching module 32 switches the four-way valve 207 to connect one end thereof to the first lubricating oil return port 105 away from the top of the evaporator 204 in the height direction, so that the lubricating oil mixed with the liquid refrigerant and floating on the surface of the liquid refrigerant flows out of the evaporator 204 for recovery through the first lubricating oil return port 105.

[0069] Meanwhile, according to the flow rate of the lubricating oil flowing out of the evaporator 204, the four-way valve 207 is switched to connect the other end thereof to the first ejector 205 or the second ejector 206 with a more suitable model and flow rate.

[0070] The control device 3 further includes the solenoid valve control module 33. When the four-way valve switching module 32 controls the four-way valve 207 to be connected to the first ejector 205, the first solenoid valve 208 communicating with the first ejector 205 is controlled to open, and the second solenoid valve 209 communicating with the second ejector 206 is controlled to close. When the four-way valve switching module 32 controls the four-way valve 207 to be connected to the second ejector 206, the second solenoid valve 209 communicating with the second ejector 206 is controlled to open, and the first solenoid valve 208 communicating with the first ejector 205 is controlled to close.

[0071] Through the above control device 3, according to the current liquid level of the evaporator 204 detected by the evaporator liquid level detection module 31, the connection of the four-way valve 207 and the opening and closing of the first solenoid valve 208 and the second solenoid valve 209 are more flexibly controlled. When the liquid level in the evaporator 204 changes, the four-way valve 207 can be quickly switched to the first lubricating oil return port 105 or the second lubricating oil return port 106 matching the liquid level, thereby improving the oil recovery efficiency of the refrigeration system 2 and the operating stability of the refrigeration system 2.

[0072] The above embodiments are merely exemplary embodiments of the invention and are not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made to the exemplary embodiments within the scope of the claims is to be included in the protection scope of the invention.

Examples

first embodiment

[0023]Fig. 1 is a schematic structural diagram of a heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a Referring to Fig. 1, the heat exchanger 1 includes a heat exchanger shell 101, a refrigerant inlet 102, a refrigerant outlet 103, a heat exchange tube bundle 104, a first lubricating oil return port 105, and a second lubricating oil return port 106.

[0024]As shown in Fig. 1, the heat exchanger shell 101 encloses a heat exchanger shell cavity 101a, the refrigerant inlet 102 is opened at the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a, and the refrigerant outlet 103 is opened at the top of the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a. The heat exchange tube bundle 104 is further arranged in the heat exchanger shell cavity 101a, and an external heat exchange medium enters the heat exchange tube bundle 104 to exchange heat with a refrigerant circula...

second embodiment

[0033]Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0034]Fig. 2 is a schematic structural diagram of the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the second embodiment. Referring to Fig. 2, different from the heat exchanger 1 according to the first embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the second embodiment are arranged at different positions along an extension direction of the heat exchange tube bundle 104.

[0035]The refrigerant exchanges heat with a heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger she...

third embodiment

[0038]Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0039]Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to the third embodiment. Referring to Fig. 3, different from the heat exchanger 1 according to the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the third embodiment are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101. Further preferably, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extens...

BACKGROUND

[0001] This invention relates to the technical field of refrigeration / cooling equipment, in particular to a heat exchanger capable of recovering lubricating oil according to liquid level changes, a refrigeration system using the heat exchanger as an evaporator, and a control device for controlling an operation of the refrigeration system.

[0002] For a refrigeration system, lubricating oil is usually required to reduce friction between rotary parts of a compressor. When a refrigerant participates in a refrigeration cycle in the refrigeration system, part of the lubricating oil in the compressor may be mixed with the refrigerant to enter the refrigeration cycle. When the lubricating oil flows into a heat exchanger as an evaporator with a liquid refrigerant, the refrigerant in a heat exchanger shell cavity exchanges heat with a heat exchange medium in a heat exchange tube bundle, so that the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant, the gaseous refrigerant flows out of the heat exchanger through a refrigerant outlet arranged at the top of the heat exchanger, and part of the lubricating oil that is mixed with the liquid refrigerant to enter the heat exchanger remains in the heat exchanger shell cavity.

[0003] In the prior art, a lubricating oil return port is provided on a side surface of a heat exchanger shell, so that the lubricating oil in the heat exchanger flows out of the heat exchanger through the lubricating oil return port, thereby avoiding the problem that part of the lubricating oil remains in the heat exchanger, resulting in the reduction of the lubricating oil in the compressor or the influence on the heat exchange efficiency in the heat exchanger.

[0004] However, when a working condition, a load and the like of the heat exchanger change, a flow rate of the refrigerant flowing into the heat exchanger, an evaporation rate inside the heat exchanger and the like change correspondingly, which may affect a liquid level inside the heat exchanger. When a current liquid level inside the heat exchanger is below or above the lubricating oil return port, the lubricating oil, which is mainly located at the liquid level of the refrigerant in the heat exchanger, may not be recovered in time, which affects the operation of the compressor.SUMMARY

[0005] The invention aims to provide a heat exchanger that can recover lubricating oil according to liquid level changes, so as to at least solve or alleviate some of the problems existing in the prior art.

[0006] A first aspect of the invention provides a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system, the heat exchanger including: a heat exchanger shell enclosing a heat exchanger shell cavity; a refrigerant inlet opened in the heat exchanger shell and communicating with the heat exchanger shell cavity; a refrigerant outlet opened at the top of the heat exchanger shell and communicating with the heat exchanger shell cavity; a heat exchange tube bundle arranged in the heat exchanger shell cavity and configured to allow a heat exchange medium for heat exchange of the refrigerant in the heat exchanger shell cavity to circulate therethrough, a first lubricating oil return port opened on a side surface of the heat exchanger shell and communicating with the heat exchanger shell cavity; and a second lubricating oil return port opened on the side surface of the heat exchanger shell and closer to the top of the heat exchanger shell than the first lubricating oil return port.

[0007] In one or more embodiments, a distance L between the first lubricating oil return port and the second lubricating oil return port in a height direction of the side surface of the heat exchanger shell and a height H of the side surface of the heat exchanger shell satisfy a numerical relationship 1 10 H < L < 1 2 H.

[0008] In one or more embodiments, the first lubricating oil return port and the second lubricating oil return port are arranged at different positions in a direction of the heat exchange tube bundle.

[0009] In one or more embodiments, the first lubricating oil return port and the second lubricating oil return port are arranged at the same position in a height direction of the side surface of the heat exchanger shell.

[0010] A second aspect of the invention provides a refrigeration system including: a compressor having a suction-side primary suction chamber, a condenser, and an evaporator, which are connected in sequence through a refrigerant pipeline, in which the evaporator is the heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to any one of the above technical solutions. The refrigeration system further includes: a first ejector having an input end in communication with the first lubricating oil return port and a power end in communication with an exhaust side of the compressor; and a second ejector having an input end in communication with the second lubricating oil return port and a power end in communication with the exhaust side of the compressor.

[0011] In one or more embodiments, an output end of the first ejector communicates with a suction side of the compressor, and an output end of the second ejector communicates with a suction side of the compressor.

[0012] In one or more embodiments, the refrigeration system further includes: a lubricating oil tank in communication with an output end of the first ejector and an output end of the second ejector; and a bypass pipeline having one end connected to the lubricating oil tank and the other end connected to the suction-side primary suction chamber of the compressor.

[0013] In one or more embodiments, the refrigeration system further includes: a four-way valve in communication with the first lubricating oil return port, the second lubricating oil return port, the input end of the first ejector and the input end of the second ejector separately, and configured to enable the first lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector, and the second lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector.

[0014] In one or more embodiments, the refrigeration system further includes: a first solenoid valve arranged in a pipeline in communication with the power end of the first ejector; and a second solenoid valve arranged in a pipeline in communication with the power end of the second ejector.

[0015] In one or more embodiments, the refrigeration system further includes: a lubricating oil pump arranged inside the lubricating oil tank and configured to allow the lubricating oil tank to communicate with an oil supply pipeline on a lubricating oil inlet side of the compressor.

[0016] In one or more embodiments, the refrigeration system further includes: a third ejector having an input end in communication with the suction-side primary suction chamber of the compressor and a power end in communication with an exhaust side of the compressor, the output end being in communication with the lubricating oil tank.

[0017] In one or more embodiments, the refrigeration system further includes: a lubricating oil heater arranged in the lubricating oil tank.

[0018] A third aspect of the invention provides a control device for regulating and controlling the refrigeration system according to the above technical solution, the control device including: an evaporator liquid level detection module configured to detect and record a current liquid level of the evaporator in real time; a four-way valve switching module configured to enable, according to the current liquid level of the evaporator detected by the evaporator liquid level detection module, one end of the four-way valve to be connected to the first lubricating oil return port or the second lubricating oil return port, and the other end of the four-way valve to be connected to the first ejector or the second ejector; and a solenoid valve control module configured to control the first solenoid valve to open and the second solenoid valve to close when the four-way valve is switched to communicate with the first ejector, and control the second solenoid valve to open and the first solenoid valve to close when the four-way valve is switched to communicate with the second ejector.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0019] Fig. 1 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a first embodiment. Fig. 2 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a second embodiment of. Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to a third embodiment. Fig. 4 is a schematic diagram of modules of a refrigeration system according to a fourth embodiment. Fig. 5 is a schematic diagram of modules of a refrigeration system according to the fourth embodiment. Fig. 6 is a schematic diagram of modules of a refrigeration system according to a fifth embodiment. Fig. 7 is a schematic diagram of modules of a control device according to a sixth embodiment.

[0020] Reference numerals: heat exchanger 1, heat exchanger shell 101, heat exchanger shell cavity 101a, refrigerant inlet 102, refrigerant outlet 103, heat exchange tube bundle 104, heat exchange medium inlet 1041, heat exchange medium outlet 1042, first lubricating oil return port 105, second lubricating oil return port 106, refrigeration system 2, refrigerant pipeline 201, compressor 202, suction-side primary suction chamber 2021, condenser 203, evaporator 204, first ejector 205, second ejector 206, four-way valve 207, first solenoid valve 208, second solenoid valve 209, lubricating oil tank 210, bypass pipeline 2101, lubricating oil inlet 2102, lubricating oil pump 211, lubricating oil heater 212, third ejector 213, third solenoid valve 214, control device 3, evaporator liquid level detection module 31, four-way valve switching module 32, and solenoid valve control module 33.DETAILED DESCRIPTION OF THE DISCLOSURE

[0021] It should be noted that working principles, features, advantages, and the like of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system will be explained below by way of embodiments. However, it should be understood that all descriptions are only given for exemplification and therefore these embodiments should not be understood as forming any limitation on the invention.

[0022] In addition, for any single technical feature described or implicit in some embodiments mentioned herein, or any single technical feature shown or implicit in the drawings, the invention still allows any combination or deletion between these technical features (or their equivalents) without any technical obstacles, thereby obtaining more other embodiments of the invention that may not be directly mentioned herein, but that are nevertheless within the scope of the invention defined by the claims.

[0023] Fig. 1 is a schematic structural diagram of a heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a first embodiment. Referring to Fig. 1, the heat exchanger 1 includes a heat exchanger shell 101, a refrigerant inlet 102, a refrigerant outlet 103, a heat exchange tube bundle 104, a first lubricating oil return port 105, and a second lubricating oil return port 106.

[0024] As shown in Fig. 1, the heat exchanger shell 101 encloses a heat exchanger shell cavity 101a, the refrigerant inlet 102 is opened at the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a, and the refrigerant outlet 103 is opened at the top of the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a. The heat exchange tube bundle 104 is further arranged in the heat exchanger shell cavity 101a, and an external heat exchange medium enters the heat exchange tube bundle 104 to exchange heat with a refrigerant circulating in the heat exchanger shell cavity 101a. Specifically, a liquid refrigerant mixed with lubricating oil flows into the interior of the heat exchanger shell cavity 101a through the refrigerant inlet 102, exchanges heat with the heat exchange medium such as hot water in the heat exchange tube bundle 104, so that the temperature of the liquid refrigerant increases, the liquid refrigerant evaporates into a gaseous state, and the evaporated refrigerant gas flows out of the heat exchanger 1 through the refrigerant outlet 103 arranged at the top of the heat exchanger shell 101.

[0025] The heat exchanger shell 101 is further provided with the first lubricating oil return port 105 and the second lubricating oil return port 106, the first lubricating oil return port 105 and the second lubricating oil return port 106 are both opened on a side surface of the heat exchanger shell 101, and the second lubricating oil return port 106 is closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105, that is, closer to the refrigerant outlet 103.

[0026] When a flow rate of the refrigerant flowing into the heat exchanger 1 decreases, or the flow rate of the refrigerant flowing into the heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into the heat exchanger 1 increases, an evaporation rate of the liquid refrigerant is relatively high, that is, when a liquid level of the liquid refrigerant in the heat exchanger 1 is at a lower position, the lubricating oil mixed with the liquid refrigerant and floating on a surface of the liquid refrigerant may flow out of the heat exchanger 1 through the first lubricating oil return port 105 (that is, the lubricating oil return port located at the lower position on the side surface of the heat exchanger shell 101) opened at the side surface of the heat exchanger shell 101.

[0027] When the flow rate of the refrigerant flowing into the heat exchanger 1 increases, or the flow rate of the refrigerant flowing into the heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into the heat exchanger 1 decreases, the evaporation rate of the liquid refrigerant is relatively low, which may cause the liquid level of the liquid refrigerant in the heat exchanger 1 to be at a higher position, so that at this time, the lubricating oil mixed with the liquid refrigerant and floating on a liquid level surface of the liquid refrigerant may flow out of the heat exchanger 1 through the second lubricating oil return port 106 opened on the side surface of the heat exchanger shell 101 and closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105.

[0028] According to the above embodiment, in the heat exchanger, the first lubricating oil return port 105 or the second lubricating oil return port 106 at different heights may be selected according to different liquid levels of the refrigerant in the heat exchanger shell cavity 101a, so that the lubricating oil return port matches the liquid level of the refrigerant in the heat exchanger shell cavity 101a, thereby avoiding the problem that when a working condition of the heat exchanger 1 changes, that is, when the liquid level of the refrigerant in the heat exchanger shell cavity 101a changes, the liquid level of the refrigerant does not match the height of the lubricating oil return port, and consequently, the lubricating oil mainly near the liquid level surface of the refrigerant cannot be recovered in time through the lubricating oil return port, affecting an operation of the refrigeration system.

[0029] It should be noted that although the refrigerant inlet 102 and the refrigerant outlet 103 of the heat exchanger 1 shown in Fig. 1 are staggered, the invention is not limited thereto, and the arrangement of the refrigerant inlet 102 and the refrigerant outlet 103 flexibly designed according to different operating conditions, process designs, and the like of the heat exchanger 1 should be included in the protection scope of the invention.

[0030] As a preferred embodiment, a distance L between the first lubricating oil return port 105 and the second lubricating oil return port 106 in a height direction of the side surface of the heat exchanger shell 101 and a height H of the side surface of the heat exchanger shell 101 satisfy a numerical relationship 1 10 H < L < 1 2 H.

[0031] Through the above embodiment, the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 is set to L > 1 10 H, which avoids the problem that when the liquid level of the refrigerant inside the heat exchanger shell cavity 101a changes greatly, the excessively small distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 results in an inability to match the liquid level change inside the heat exchanger shell cavity 101a even if the first lubricating oil return port 105 or the second lubricating oil return port 106 is switched. At the same time, the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 is set to L < 1 2 H, which avoids the problem that when the liquid level of the refrigerant inside the heat exchanger shell cavity 101a changes greatly and still does not drop (or rise) to reach the first lubricating oil return port 105 (or second lubricating oil return port 106), the excessively large distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 causes the connected lubricating oil return port to be unable to match the liquid level change of the refrigerant in the heat exchanger shell cavity 101a in time.

[0032] It should be noted that although the first lubricating oil return port 105 and the second lubricating oil return port 106 are described as an example in some embodiments, the invention is not limited thereto, and the arrangement of adding more lubricating oil return ports according to different operating conditions of the refrigeration system 2, models and parameters of the heat exchanger 1, and the like are also included in the protection scope of the invention.

[0033] Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a second embodiment and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0034] Fig. 2 is a schematic structural diagram of the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the second embodiment. Referring to Fig. 2, different from the heat exchanger 1 according to the first embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the second embodiment are arranged at different positions along an extension direction of the heat exchange tube bundle 104.

[0035] The refrigerant exchanges heat with a heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger shell cavity 101a, and the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, in a flow direction of the heat exchange medium, a liquid refrigerant close to a heat exchange medium inlet 1041 sufficiently evaporates into a gaseous refrigerant upon absorbing heat, and thus a liquid level of the liquid refrigerant is relatively low, while a liquid refrigerant close to a heat exchange medium outlet 1042 does not evaporate sufficiently into a gaseous refrigerant upon absorbing heat due to a small temperature difference, and thus a liquid level of the liquid refrigerant is relatively high. Thus, there is a difference in the liquid level of the liquid refrigerant at different positions along the extension direction of the heat exchange tube bundle 104 in the heat exchanger 1. Generally speaking, the liquid level of the liquid refrigerant close to the heat exchange medium inlet 1041 is relatively low, and the liquid level of the liquid refrigerant close to the heat exchange medium outlet 1042 is relatively high. In addition, as the liquid refrigerant evaporates, the liquid level of the liquid refrigerant may also fluctuate inside the heat exchanger shell cavity 101a along the extension direction of the heat exchange tube bundle 104.

[0036] Through the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 are arranged at different positions along the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is closer to the top of the heat exchanger shell 101 than the first lubricating oil return port 105. Preferably, the first lubricating oil return port 105 is arranged at a position close to the heat exchange medium inlet 1041 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged at a position close to the heat exchange medium outlet 1042 in the extension direction of the heat exchange tube bundle 104. The second lubricating oil return port 106 closer to the top of the heat exchanger shell 101 corresponds to a position close to the heat exchange medium outlet 1042 with a higher liquid level in the heat exchanger shell cavity 101a, and the first lubricating oil return port 105 corresponds to a position close to the heat exchange medium inlet 1041 with a lower liquid level in the heat exchanger shell cavity 101a. This avoids the problem that when only one fixed lubricating oil return port is used, the oil return efficiency may be affected due to uneven distribution of the lubricating oil within the heat exchanger 1 or its accumulation primarily on one side.

[0037] It should be noted that although the first lubricating oil return port 105 and the second lubricating oil return port 106 are provided at different positions in the extension direction of the heat exchange tube bundle 104 as an example for description in some embodiments, the invention is not limited thereto, and the manner of providing a plurality of lubricating oil return ports according to the extension direction of the heat exchange tube bundle 104 of the heat exchanger 1 and different liquid levels are also included in the protection scope of the invention.

[0038] Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a third embodiment and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0039] Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to the third embodiment. Referring to Fig. 3, different from the heat exchanger 1 according to the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the third embodiment are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101. Further preferably, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged farther from the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104.

[0040] The refrigerant exchanges heat with the heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger shell cavity 101a, and the liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, in a working state, the refrigerant is consistently in a localized boiling and vaporization state in the heat exchanger shell cavity 101a, and violent vaporization occurs on both the inside and the surface of the refrigerant liquid, which may cause the liquid level of the refrigerant in the heat exchanger shell cavity 101a to fluctuate.

[0041] When the liquid level of the refrigerant inside the heat exchanger shell cavity 101a fluctuates greatly due to the boiling and vaporization state, for example, a liquid level of a refrigerant close to (or away from) the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104 rises to the height of the first lubricating oil return port 105 (or second lubricating oil return port 106), and at this time, the lubricating oil mixed with the liquid refrigerant and floating on the liquid level surface of the liquid refrigerant may flow out of the heat exchanger 1 through the first lubricating oil return port 105 (or second lubricating oil return port 106).

[0042] The first lubricating oil return port 105 and the second lubricating oil return port 106 are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is arranged farther from the refrigerant outlet 103 in the extension direction of the heat exchange tube bundle 104, so that the lubricating oil mixed with the liquid refrigerant and floating on the liquid level surface of the liquid refrigerant can flow out of the heat exchanger 1 for recovery through the first lubricating oil return port 105 or the second lubricating oil return port 106 matching the liquid level in the heat exchanger shell cavity 101a according to the liquid level in the heat exchanger shell cavity 101a, especially the liquid level fluctuation caused by the refrigerant being in the boiling state. Through the above embodiment, even if the liquid level in the heat exchanger shell cavity 101a frequently fluctuates, it is still possible to allow the lubricating oil to flow out through either the first lubricating oil return port 105 or the second lubricating oil return port 106, depending on which one matches the current liquid level, thereby improving the oil return efficiency of the refrigeration system and the operation stability of the refrigeration system.

[0043] It should be noted that, in some embodiments, specific positions of the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 are not limited, and the form in which different specific positions of the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction of the side surface of the heat exchanger shell 101 are set according to parameters such as an operating condition of the refrigeration system, a refrigerant charge amount in the refrigeration system, and a model of the heat exchanger 1.

[0044] A fourth embodiment provides a refrigeration system 2 including a compressor 202, a condenser 203 and an evaporator 204, which are connected in sequence through a refrigerant pipeline. The compressor 202 has a suction-side primary suction chamber 2021, and the evaporator 204 is the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiments.

[0045] Fig. 4 is a schematic diagram of modules of a refrigeration system according to a fourth embodiment. Referring to Fig. 4, the refrigeration system 2 according to the fourth embodiment further includes a first ejector 205, a second ejector 206, a lubricating oil tank 210, a bypass pipeline 2101, a lubricating oil inlet 2102, and a lubricating oil pump 211.

[0046] The ejector has an input end, an output end and a power end, and the input end is connected to a nozzle of the ejector. As shown in Fig. 4, an input end of the first ejector 205 communicates with the first lubricating oil return port 105, a power end of the first ejector 205 communicates with an exhaust side of the compressor 202, an input end of the second ejector 206 communicates with the second lubricating oil return port 106, a power end of the second ejector 206 communicates with the exhaust side of the compressor 202, and an output end of the first ejector 205 and an output end of the second ejector 206 both communicate with a suction side of the compressor 202.

[0047] The refrigeration system 2 according to the fourth embodiment further includes the lubricating oil tank 210 arranged at a lowest part of the refrigeration system 2, one end of the bypass pipeline 2101 is connected to the lubricating oil tank 210, the other end of the bypass pipeline 2101 is connected to the suction-side primary suction chamber 2021 of the compressor, lubricating oil delivered to the suction-side primary suction chamber 2021 of the compressor through the output end of the first ejector 205 and the output end of the second ejector 206 flows to the lubricating oil tank 210 through the bypass pipeline 2021 under the action of gravity.

[0048] The lubricating oil tank 210 is further provided with the lubricating oil pump 211, one end of the oil supply pipeline where the lubricating oil pump 211 is located communicates with the lubricating oil tank 210, and the other end of the oil supply pipeline communicates with the lubricating oil inlet 2102 of the compressor 202. When it is detected that the amount of lubricating oil in the compressor 202 is reduced or lower than the demand amount, the lubricating oil pump 211 provides a driving force for the lubricating oil in the lubricating oil tank 210, so that the lubricating oil stored in the lubricating oil tank 210 is conveyed to the compressor 202, thereby preventing the operation of the compressor 202 from being affected by insufficient lubricating oil.

[0049] Through the above embodiment, a high-pressure gaseous refrigerant discharged by the compressor 202 flows into the first ejector 205 or the second ejector 206 through the power end, and flows out at a faster speed through a nozzle of the first ejector 205 or the second ejector 206. The downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts the lubricating oil (possibly including part of the liquid or gaseous refrigerant) flowing out of the evaporator 204 from the first lubricating oil return port 105 or the second lubricating oil return port 106 in communication with the input end of the first ejector 205 or the second ejector 206. The lubricating oil passing through the first ejector 205 or the second ejector 206 is mixed with the refrigerant and then flows into the suction-side primary suction chamber 2021 of the compressor 202 through the output end of the first ejector 205 or the second ejector 206, so that the lubricating oil is temporarily stored at the bottom of the suction-side primary suction chamber 2021 of the compressor 202. Under the action of gravity, the lubricating oil temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 flows to the lubricating oil tank 210 through the bypass pipeline 2021 with one end connected to the suction-side primary suction chamber 2021 of the compressor 202 and the other end connected to the lubricating oil tank 210, thereby completing the oil recovery of the lubricating oil while achieving the pressure balance in the refrigeration system 2.

[0050] At the same time, a part of the high-temperature and high-pressure gaseous refrigerant flowing out of the exhaust side of the compressor 202 also returns to the suction side of the compressor 202 after passing through the first ejector 205 or the second ejector 206, and is mixed with the gaseous refrigerant flowing out of the evaporator 204, so that the pressure and temperature of the refrigerant flowing into the compressor 202 are increased, and the working efficiency of the compressor 202 is improved.

[0051] In this way, an air pressure difference generated when the high-pressure refrigerant discharged from the exhaust side of the compressor 202 flows through the nozzles of the first ejector 205 and the second ejector 206 provides a drainage force for the lubricating oil to flow to the first ejector 205 or the second ejector 206, thereby improving the recovery efficiency of the lubricating oil.

[0052] As a preferred embodiment, a connection pipeline between the input end of the first ejector 205 and the first lubricating oil return port 105 and a connection pipeline between the input end of the second ejector 206 and the second lubricating oil return port 106 are further provided with a four-way valve 207, and four valve ports of the four-way valve 207 can communicate with the input end of the first ejector 205, the first lubricating oil return port 105, the input end of the second ejector 206 and the second lubricating oil return port 106, respectively.

[0053] Therefore, by adjusting the switching of the four-way valve 207, the first lubricating oil return port 105 can be controlled to communicate with the input end of the first ejector 205 or the input end of the second ejector 206, or the second lubricating oil return port 106 can be controlled to communicate with the input end of the first ejector 205 or the input end of the second ejector 206.

[0054] Through the above embodiment, when the lubricating oil from the evaporator 204 is recovered through the first lubricating oil return port 105 (or second lubricating oil return port 106), the four-way valve can be switched to communicate with the matching first ejector 205 or second ejector 206 according to the conditions such as a flow rate and pressure of the fluid flowing out of the evaporator 204 from the first lubricating oil return port 105 (or second lubricating oil return port 106), so that the working efficiency and reliability of the ejector are improved, and the possibility is also reduced that the use of an ejector that does not match the actual flow rate and pressure of the fluid results in a mismatch between a suction force of the fluid flowing out of the evaporator 204 and the flow rate, resulting in an inadequate drainage of the lubricating oil flowing out of the first lubricating oil return port 105 (or second lubricating oil return port 106), thereby reducing the oil recovery efficiency.

[0055] As a preferred embodiment, according to the liquid level change inside the evaporator 204, the four-way valve 207 is controlled to simultaneously connect the first lubricating oil return port 105 with the first ejector 205 and the second ejector 206 or simultaneously connect the second lubricating oil return port 106 with the first ejector 205 and the second ejector 206, that is, the first ejector 205 and the second ejector 206 always work simultaneously, and the four-way valve 207 can be switched to communicate with the matching first lubricating oil return port 105 or second lubricating oil return port 106 according to the liquid level change inside the evaporator 204.

[0056] Through the above embodiment, when the flow rate of the fluid flowing out of the first lubricating oil return port 105 (or second lubricating oil return port 106) is large, the four-way valve 207 communicates with the first ejector 205 and the second ejector 206 simultaneously, so that the first ejector 205 and the second ejector 206 always work simultaneously, and the four-way valve 207 can be switched to communicate with the matching first lubricating oil return port 105 or second lubricating oil return port 106 according to the adjustment of the liquid level in the evaporator 204, thereby improving the oil recovery efficiency and reliability of the refrigeration system.

[0057] Fig. 5 is a schematic diagram of modules of a refrigeration system according to the fourth embodiment. Referring to Fig. 5, further preferably, a first solenoid valve 208 is further arranged on the pipeline in communication with the power end of the first ejector 205, and a second solenoid valve 209 is further arranged on the pipeline in communication with the power end of the second ejector 206.

[0058] When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or second lubricating oil return port 106) to the first ejector 205, the first solenoid valve 208 is controlled to open and the second solenoid valve 209 is controlled to close. At this time, a small part of the refrigerant carrying the lubricating oil flowing out of the compressor 202 flows into the first ejector 205 through the first solenoid valve 208, and a main part thereof flows into the condenser 203 to continue a refrigeration cycle. When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or second lubricating oil return port 106) to the second ejector 206, the first solenoid valve 208 is controlled to close, and the second solenoid valve 209 is controlled to open. At this time, a small part of the refrigerant carrying the lubricating oil flowing out of the compressor 202 flows into the second ejector 206 through the second solenoid valve 209, and a main part thereof flows into the condenser 203 to continue the refrigeration cycle.

[0059] By switching the four-way valve 207 and controlling the opening and closing of the first solenoid valve 208 or the second solenoid valve 209, the first ejector 205 or the second ejector 206 is switched to be connected according to the working conditions such as the flow rate and pressure of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106), thereby improving the oil recovery efficiency of the refrigeration system 2, and also avoiding the problem that the high-temperature and high-pressure gaseous refrigerant flowing out of the compressor 202 returns to the suction side of the compressor 202 through the first ejector 205 and the second ejector 206 simultaneously, thereby reducing the refrigerant participating in the refrigeration cycle and lowering the heat exchange efficiency. At the same time, the first solenoid valve 208 or the second solenoid valve 209 corresponding to the first ejector 205 or the second ejector 206 that does not communicate with the first lubricating oil return port 105 (or second lubricating oil return port 106) is controlled to close, thereby solving the problem that it is difficult to balance a pressure difference inside the unconnected first ejector 205 or second ejector 206, and improving the reliability of the refrigeration system 2.

[0060] Although some embodiments are described in the form of the first ejector 205, the second ejector 206 and the corresponding first solenoid valve 208 and second solenoid valve 209, the invention is not limited thereto. The form of arranging more ejectors and corresponding solenoid valves according to the operating conditions of the refrigeration system 2, the model parameters of the evaporator 204, the model parameters of the ejector and the like are included in the protection scope of the invention.

[0061] Elements denoted by the same names and symbols as those in the refrigeration system 2 according to a fifth embodiment and the refrigeration system 2 according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0062] Fig. 6 is a schematic diagram of modules of the refrigeration system according to the fifth embodiment. Referring to Fig. 6, the refrigeration system 2 according to the fifth embodiment further includes a lubricating oil heater 212 arranged in the lubricating oil tank 210.

[0063] The refrigerant in the lubricating oil stored in the lubricating oil tank 210 is heated by the lubricating oil heater 212 arranged in the lubricating oil tank 210 to accelerate evaporation of the refrigerant, and the evaporated refrigerant returns to the suction-side primary suction chamber 2021 of the compressor 202 through the bypass pipeline 2101 to continue the refrigeration cycle, thereby avoiding the problem that the excessive refrigerant remaining in the lubricating oil tank 210 causes the temperature of the lubricating oil stored in the lubricating oil tank 210 to become too low, thereby affecting an lubrication effect.

[0064] Preferably, a third ejector 213 is further provided in a pipeline connecting the lubricating oil tank 210 and the output end of the first ejector 205 or the second ejector 206, and the third ejector 213 has an input end in communication with the suction-side primary suction chamber of the compressor, a power end in communication with the exhaust side of the compressor, and an output end communication with the lubricating oil tank.

[0065] Through the above embodiment, the high-pressure gaseous refrigerant discharged by the compressor 202 flows into the third ejector 213 through the power end, and flows out at a faster speed through a nozzle of the third ejector 213, and a downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts an oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 in communication with the input end of the third ejector 213. The oil-containing refrigerant passing through the third ejector 213 flows into the lubricating oil tank 210 through the output end of the third ejector 213, so that the bypass pipeline 2101 and the third ejector 213 cooperate to realize oil recovery of the lubricating oil, thereby improving the oil recovery efficiency.

[0066] Preferably, a third solenoid valve 214 is further provided in a pipeline connecting the power end of the third ejector 213 and the exhaust side of the compressor 202, and the opening and closing of the third solenoid valve 214 is controlled according to conditions such as the flow rate and pressure of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106). Specifically, when the flow rate of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106) is small, the third solenoid valve 214 is controlled to close. At this time, the third ejector 213 attracts the oil-containing refrigerant in the suction-side primary suction chamber 2021 of the compressor 202 by forming a bypass pipeline at the input end and the output end of the third ejector 213 under the action of gravity instead of forming the low-pressure area, and the oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 flows into the lubricating oil tank 210 through the input end and the output end of the third ejector 213 under the action of gravity. When the flow rate of the fluid flowing out of the evaporator 204 through the first lubricating oil return port 105 (or second lubricating oil return port 106) is large, the third solenoid valve 214 is controlled to open. At this time, the high-pressure gaseous refrigerant discharged from the compressor 202 flows into the third ejector 213 through the power end, and the downstream side of the nozzle communicates with the input end to form a low-pressure area. The low-pressure area attracts the oil-containing refrigerant temporarily stored in the suction-side primary suction chamber 2021 of the compressor 202 in communication with the input end of the third ejector 213, thereby improving the oil recovery efficiency.

[0067] A control device is further provided for regulating and controlling the refrigeration system 2. Fig. 7 is a schematic diagram of modules of a control device according to a sixth embodiment. Referring to Fig. 7, the sixth embodiment provides a control device 3 for regulating and controlling the refrigeration system 2 according to any one of the above embodiments, and the control device 3 includes an evaporator liquid level detection module 31, a four-way valve switching module 32, and a solenoid valve control module 33.

[0068] The evaporator liquid level detection module 31 detects and records a current liquid level of the evaporator 204 in real time. When the current liquid level detected by the evaporator liquid level detection module 31 is high, the four-way valve switching module 32 switches the four-way valve 207 to connect one end thereof to the second lubricating oil return port 106 closer to the top of the evaporator 204, so that the lubricating oil mixed with the liquid refrigerant and floating on the surface of the liquid refrigerant flows out of the evaporator 204 for recovery through the second lubricating oil return port 106. When the current liquid level detected by the evaporator liquid level detection module 31 is low, the four-way valve switching module 32 switches the four-way valve 207 to connect one end thereof to the first lubricating oil return port 105 away from the top of the evaporator 204 in the height direction, so that the lubricating oil mixed with the liquid refrigerant and floating on the surface of the liquid refrigerant flows out of the evaporator 204 for recovery through the first lubricating oil return port 105.

[0069] Meanwhile, according to the flow rate of the lubricating oil flowing out of the evaporator 204, the four-way valve 207 is switched to connect the other end thereof to the first ejector 205 or the second ejector 206 with a more suitable model and flow rate.

[0070] The control device 3 further includes the solenoid valve control module 33. When the four-way valve switching module 32 controls the four-way valve 207 to be connected to the first ejector 205, the first solenoid valve 208 communicating with the first ejector 205 is controlled to open, and the second solenoid valve 209 communicating with the second ejector 206 is controlled to close. When the four-way valve switching module 32 controls the four-way valve 207 to be connected to the second ejector 206, the second solenoid valve 209 communicating with the second ejector 206 is controlled to open, and the first solenoid valve 208 communicating with the first ejector 205 is controlled to close.

[0071] Through the above control device 3, according to the current liquid level of the evaporator 204 detected by the evaporator liquid level detection module 31, the connection of the four-way valve 207 and the opening and closing of the first solenoid valve 208 and the second solenoid valve 209 are more flexibly controlled. When the liquid level in the evaporator 204 changes, the four-way valve 207 can be quickly switched to the first lubricating oil return port 105 or the second lubricating oil return port 106 matching the liquid level, thereby improving the oil recovery efficiency of the refrigeration system 2 and the operating stability of the refrigeration system 2.

[0072] The above embodiments are merely exemplary embodiments of the invention and are not intended to limit the invention. Any modifications, equivalent substitutions, and improvements made to the exemplary embodiments within the scope of the claims is to be included in the protection scope of the invention.

Examples

first embodiment

[0023]Fig. 1 is a schematic structural diagram of a heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to a Referring to Fig. 1, the heat exchanger 1 includes a heat exchanger shell 101, a refrigerant inlet 102, a refrigerant outlet 103, a heat exchange tube bundle 104, a first lubricating oil return port 105, and a second lubricating oil return port 106.

[0024]As shown in Fig. 1, the heat exchanger shell 101 encloses a heat exchanger shell cavity 101a, the refrigerant inlet 102 is opened at the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a, and the refrigerant outlet 103 is opened at the top of the heat exchanger shell 101 and communicates with the heat exchanger shell cavity 101a. The heat exchange tube bundle 104 is further arranged in the heat exchanger shell cavity 101a, and an external heat exchange medium enters the heat exchange tube bundle 104 to exchange heat with a refrigerant circula...

second embodiment

[0033]Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0034]Fig. 2 is a schematic structural diagram of the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the second embodiment. Referring to Fig. 2, different from the heat exchanger 1 according to the first embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the second embodiment are arranged at different positions along an extension direction of the heat exchange tube bundle 104.

[0035]The refrigerant exchanges heat with a heat exchange medium in the heat exchange tube bundle 104 in the heat exchanger she...

third embodiment

[0038]Elements denoted by the same names and symbols as those in the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system and the heat exchanger 1 for absorbing heat and evaporating a refrigerant in a refrigeration system according to the above embodiment represent identical components, and descriptions thereof are omitted here.

[0039]Fig. 3 is a schematic structural diagram of a heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to the third embodiment. Referring to Fig. 3, different from the heat exchanger 1 according to the above embodiment, the first lubricating oil return port 105 and the second lubricating oil return port 106 according to the third embodiment are arranged at the same position in the height direction of the side surface of the heat exchanger shell 101. Further preferably, the first lubricating oil return port 105 is arranged closer to the refrigerant outlet 103 in the extens...

Claims

1. A heat exchanger (1) for absorbing heat and evaporating a refrigerant in a refrigeration system, the heat exchanger comprising: a heat exchanger shell (101) enclosing a heat exchanger shell cavity (101a); a refrigerant inlet (102) opened in the heat exchanger shell and communicating with the heat exchanger shell cavity; a refrigerant outlet (103) opened at the top of the heat exchanger shell and communicating with the heat exchanger shell cavity; and a heat exchange tube bundle (104) arranged in the heat exchanger shell cavity and configured to allow a heat exchange medium for heat exchange of the refrigerant in the heat exchanger shell cavity to circulate therethrough, wherein the heat exchanger further comprises: a first lubricating oil return port (105) opened on a side surface of the heat exchanger shell and communicating with the heat exchanger shell cavity; and a second lubricating oil return port (106) opened on the side surface of the heat exchanger shell and closer to the top of the heat exchanger shell than the first lubricating oil return port.

2. The heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to claim 1, wherein a distance L between the first lubricating oil return port and the second lubricating oil return port in a height direction of the side surface of the heat exchanger shell and a height H of the side surface of the heat exchanger shell satisfy a numerical relationship 1 10 H < L < 1 2 H.

3. The heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to claim 1 or 2, wherein the first lubricating oil return port and the second lubricating oil return port are arranged at different positions in a direction of the heat exchange tube bundle.

4. The heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to any preceding claim, wherein the first lubricating oil return port and the second lubricating oil return port are arranged at the same position in a height direction of the side surface of the heat exchanger shell.

5. A refrigeration system (2) comprising: a compressor (202) having a suction-side primary suction chamber (2021), a condenser (203), and an evaporator (204), which are connected in sequence through a refrigerant pipeline, the evaporator being the heat exchanger for absorbing heat and evaporating a refrigerant in a refrigeration system according to any preceding claim, wherein the refrigeration system further comprises: a first ejector (205) having an input end in communication with the first lubricating oil return port and a power end in communication with an exhaust side of the compressor; and a second ejector (206) having an input end in communication with the second lubricating oil return port and a power end in communication with the exhaust side of the compressor.

6. The refrigeration system according to claim 5, wherein an output end of the first ejector communicates with a suction side of the compressor, and an output end of the second ejector communicates with a suction side of the compressor.

7. The refrigeration system according to claim 5 or 6, further comprising: a four-way valve (207) in communication with the first lubricating oil return port, the second lubricating oil return port, the input end of the first ejector and the input end of the second ejector separately, and configured to enable the first lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector, and the second lubricating oil return port to be in communication with the input end of the first ejector or the input end of the second ejector.

8. The refrigeration system according to any of claims 5 to 7, further comprising: a first solenoid valve (208) arranged in a pipeline in communication with the power end of the first ejector; and a second solenoid valve (209) arranged in a pipeline in communication with the power end of the second ejector.

9. The refrigeration system according to any of claims 5 to 8, further comprising: a lubricating oil tank in communication with an output end of the first ejector and an output end of the second ejector; and a bypass pipeline having one end connected to the lubricating oil tank and the other end connected to the suction-side primary suction chamber of the compressor.

10. The refrigeration system according to claim 9, further comprising: a lubricating oil pump (211) arranged inside the lubricating oil tank and configured to allow the lubricating oil tank to communicate with an oil supply pipeline on a lubricating oil inlet side of the compressor.

11. The refrigeration system according to claim 10, further comprising: a third ejector (213) having an input end in communication with the suction-side primary suction chamber of the compressor and a power end in communication with an exhaust side of the compressor, the output end being in communication with the lubricating oil tank.

12. The refrigeration system according to claim 11, further comprising: a lubricating oil heater (212) arranged in the lubricating oil tank.

13. A control device (3) for regulating and controlling the refrigeration system according to claim 8, the control device comprising: an evaporator liquid level detection module (31) configured to detect and record a current liquid level of the evaporator in real time; a four-way valve switching module configured to enable, according to the current liquid level of the evaporator detected by the evaporator liquid level detection module, one end of the four-way valve to be connected to the first lubricating oil return port or the second lubricating oil return port, and the other end of the four-way valve to be connected to the first ejector or the second ejector; and a solenoid valve control module configured to control the first solenoid valve to open and the second solenoid valve to close when the four-way valve is switched to communicate with the first ejector, and control the second solenoid valve to open and the first solenoid valve to close when the four-way valve is switched to communicate with the second ejector.

Images