Heat exchanger, Refrigeration system, Control device

Abstract

The application provides a heat exchanger capable of recycling lubricating oil according to the change of liquid level, a refrigeration system taking the heat exchanger as an evaporator and a control device for the refrigeration system. The heat exchanger has a heat exchanger shell, a refrigerant inlet, a refrigerant outlet, a heat exchange tube bundle, a first lubricating oil return port with an opening arranged on the side of the heat exchanger shell, and a second lubricating oil return port with an opening arranged on the side of the heat exchanger shell and closer to the top of the heat exchanger shell than the first lubricating oil return port. By arranging the first lubricating oil return port and the second lubricating oil return port at different positions in the height direction of the heat exchanger shell, when the working condition of the heat exchanger changes, the lubricating oil return port matched with the liquid level in the heat exchanger shell cavity is switched, so that the problem of no oil recycling and affecting the working of the compressor caused by the too large change of the liquid level in the heat exchanger shell when only one fixed lubricating oil return port is used is avoided.

Description

Technical Field

[0001] This application relates to the field of refrigeration / cooling equipment technology, specifically to a heat exchanger that can recover lubricating oil according to changes in liquid level, a refrigeration system using the heat exchanger as an evaporator, and a control device for controlling the operation of the refrigeration system. Background Technology

[0002] For refrigeration systems, lubricating oil is typically used to reduce friction between rotating parts of the compressor. When refrigerant participates in the refrigeration cycle in the refrigeration system, some of the lubricating oil in the compressor may mix with the refrigerant and enter the refrigeration cycle. When the lubricating oil flows into the heat exchanger, which acts as an evaporator, along with the liquid refrigerant, the refrigerant in the heat exchanger shell and cavity exchanges heat with the heat exchange medium in the heat exchanger tube bundle. This causes the liquid refrigerant to absorb heat and evaporate into gaseous refrigerant. The gaseous refrigerant flows out of the heat exchanger through the refrigerant outlet located at the top of the heat exchanger, while the portion of lubricating oil that mixed with the liquid refrigerant and entered the heat exchanger remains in the heat exchanger shell and cavity.

[0003] Existing technology provides a lubricating oil return port on the side of the heat exchanger housing, allowing the lubricating oil inside the heat exchanger to flow out through the lubricating oil return port. This avoids the problem of some lubricating oil remaining in the heat exchanger, which could lead to a reduction in the lubricating oil in the compressor or affect the heat exchange efficiency in the heat exchanger.

[0004] However, when the operating conditions and load of the heat exchanger change, the refrigerant flow rate into the heat exchanger and the evaporation rate inside the heat exchanger will change accordingly. This change may affect the liquid level inside the heat exchanger. If the current liquid level inside the heat exchanger is lower or higher than the height of the lubricating oil return port, the lubricating oil that is mainly at the refrigerant level in the heat exchanger may not be recovered in time, affecting the operation of the compressor. Summary of the Invention

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

[0006] This application provides a heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system, comprising: a heat exchanger housing surrounding a heat exchanger cavity; an opening disposed in the heat exchanger housing and communicating with a refrigerant inlet of the heat exchanger cavity; an opening disposed at the top of the heat exchanger housing and communicating with a refrigerant outlet of the heat exchanger cavity; a heat exchanger tube bundle disposed within the heat exchanger cavity for exchanging heat with the refrigerant within the heat exchanger cavity; an opening disposed on the side of the heat exchanger housing and communicating with a first lubricating oil return port of the heat exchanger cavity; and a second lubricating oil return port disposed on the side of the heat exchanger housing and closer to the top of the heat exchanger housing than the first lubricating oil return port.

[0007] In the optional technical solution, the distance L between the first lubricating oil return port and the second lubricating oil return port in the height direction of the heat exchanger housing side surface, and the height H of the heat exchanger housing side surface, satisfy the following formula: The relationship.

[0008] In the optional technical solution, the first lubricating oil return port and the second lubricating oil return port are set at different positions along the direction of the heat exchange tube bundle.

[0009] In the optional technical solution, the first lubricating oil return port and the second lubricating oil return port are located at the same position in the height direction of the side of the heat exchanger housing.

[0010] Another aspect of this application provides a refrigeration system, including a compressor, a condenser, and an evaporator, each having a suction-side primary suction chamber, connected sequentially via refrigerant piping. The evaporator is a heat exchanger provided in any of the above-described technical solutions, used for absorbing heat and evaporating the refrigerant in the refrigeration system. The refrigeration system further includes: a first ejector whose inlet end is connected to a first lubricating oil return port and whose power end is connected to the discharge side of the compressor; and a second ejector whose inlet end is connected to a second lubricating oil return port and whose power end is connected to the discharge side of the compressor.

[0011] In the optional technical solution, the output end of the first ejector is connected to the suction side of the compressor; the output end of the second ejector is connected to the suction side of the compressor.

[0012] In the optional technical solution, the refrigeration system further includes: a lubricating oil tank connected to the output end of the first ejector and the output end of the second ejector; and a bypass pipe with one end connected to the lubricating oil tank and the other end connected to the first-stage suction chamber on the suction side of the compressor.

[0013] In the optional technical solution, the refrigeration system further includes: a four-way valve that is connected to 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, respectively, and can switch the connection between the first lubricating oil return port and the input end of the first ejector or the input end of the second ejector, and the connection between the second lubricating oil return port and the input end of the first ejector or the input end of the second ejector.

[0014] In an optional technical solution, the refrigeration system further includes: a first solenoid valve disposed in a pipeline connected to the power end of the first ejector; and a second solenoid valve disposed in a pipeline connected to the power end of the second ejector.

[0015] In optional technical solutions, the refrigeration system also includes: a lubricating oil pump installed inside the lubricating oil tank and connecting the lubricating oil tank with the lubricating oil inlet side of the compressor.

[0016] In the optional technical solution, the refrigeration system also includes: a third ejector whose input end is connected to the first-stage suction chamber on the suction side of the compressor, whose power end is connected to the discharge side of the compressor, and whose output end is connected to the lubricating oil tank.

[0017] In optional technical solutions, the refrigeration system also includes a lubricating oil heater installed in the lubricating oil tank.

[0018] Another aspect of this application provides a control device for regulating and controlling the refrigeration system provided by the above-mentioned technical solution, comprising: a heat exchanger liquid level detection module for real-time detection and recording of the current liquid level height of the evaporator; a four-way valve switching module for switching one end of the four-way valve to a first lubricating oil return port or a second lubricating oil return port and the other end to a first ejector or a second ejector, based on the current liquid level height of the evaporator detected by the evaporator liquid level detection module; and a solenoid valve control module for controlling the first solenoid valve to open and the second solenoid valve to close when the four-way valve is switched to the first ejector, and controlling the second solenoid valve to open and the first solenoid valve to close when the four-way valve is switched to the second ejector. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a heat exchanger used to absorb heat and evaporate refrigerant in a refrigeration system according to the first embodiment of this application.

[0020] Figure 2 This is a schematic diagram of the structure of a heat exchanger used to absorb heat and evaporate refrigerant in a refrigeration system according to the second embodiment of this application.

[0021] Figure 3 This is a schematic diagram of the structure of a heat exchanger used to absorb heat and evaporate refrigerant in a refrigeration system according to the third embodiment of this application.

[0022] Figure 4A schematic diagram of the refrigeration system provided in the fourth embodiment of this application.

[0023] Figure 5 A schematic diagram of the refrigeration system provided in the fourth embodiment of this application.

[0024] Figure 6 A schematic diagram of a refrigeration system provided in the fifth embodiment of this application.

[0025] Figure 7 This is a schematic diagram of the control device provided in the sixth embodiment of this application.

[0026] Reference numerals: Heat exchanger 1, heat exchanger shell 101, heat exchanger 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, solenoid valve control module 33. Detailed Implementation

[0027] It should be noted that the following will illustrate the working principle, characteristics and advantages of the heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system according to this application by way of example. However, it should be understood that all descriptions are given for illustrative purposes only and should not be construed as forming any limitation on this application.

[0028] Furthermore, for any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature shown or implied in the various figures, this application still allows for any combination or deletion of these technical features (or their equivalents) without any technical obstacle, thereby obtaining more other embodiments of this application that may not be directly mentioned herein.

[0029] <First Implementation Method>

[0030] Figure 1 This is a schematic diagram of the structure of the heat exchanger 1 used for absorbing heat and evaporating refrigerant in the refrigeration system according to the first embodiment of this application. (See attached diagram) Figure 1As shown, the heat exchanger 1 involved in the embodiments of this application includes: a heat exchanger housing 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.

[0031] Among them, such as Figure 1 As shown, a heat exchanger housing 101 surrounds and forms a heat exchanger cavity 101a. The opening of the refrigerant inlet 102 is located at the heat exchanger housing 101 and connects to the heat exchanger cavity 101a. The opening of the refrigerant outlet 103 is located at the top of the heat exchanger housing 101 and connects to the heat exchanger cavity 101a. A heat exchange tube bundle 104 is also provided inside the heat exchanger cavity 101a. External heat exchange media enter the heat exchange tube bundle 104 and exchange heat with the refrigerant flowing inside the heat exchanger cavity 101a. Specifically, liquid refrigerant mixed with lubricating oil flows into the heat exchanger cavity 101a through the refrigerant inlet 102 and exchanges heat with the heat exchange medium, such as hot water, inside the heat exchange tube bundle 104. This causes the liquid refrigerant temperature to rise and evaporate into a gaseous state. The evaporated refrigerant gas flows out of the heat exchanger 1 through the refrigerant outlet 103 located at the top of the heat exchanger housing 101.

[0032] The heat exchanger housing 101 is also provided with a first lubricating oil return port 105 and a second lubricating oil return port 106. Both the first lubricating oil return port 105 and the second lubricating oil return port 106 open on the side of the heat exchanger housing 101. At the same time, the second lubricating oil return port 106 is closer to the top of the heat exchanger housing 101 than the first lubricating oil return port 105, that is, closer to the refrigerant outlet 103 side.

[0033] When the flow rate of refrigerant flowing into heat exchanger 1 decreases, or when the flow rate of refrigerant flowing into heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into heat exchanger 1 increases, the evaporation rate of the liquid refrigerant is faster. That is, when the liquid level of the liquid refrigerant in heat exchanger 1 is at a lower position, the lubricating oil mixed in the liquid refrigerant and floating on the surface of the liquid refrigerant can flow out of heat exchanger 1 through the first lubricating oil return port 105 (i.e., the lubricating oil return port located at a lower position on the side of heat exchanger housing 101) provided on the side of heat exchanger housing 101.

[0034] When the refrigerant flow rate into heat exchanger 1 increases, or when the refrigerant flow rate into heat exchanger 1 remains unchanged but the temperature or flow rate of the external heat exchange medium flowing into heat exchanger 1 decreases, the evaporation rate of the liquid refrigerant will become lower, which may cause the liquid level of the liquid refrigerant in heat exchanger 1 to be at a higher position. At this time, the lubricating oil mixed in the liquid refrigerant and floating on the surface of the liquid refrigerant can flow out of heat exchanger 1 through the second lubricating oil return port 106, which is set on the side of heat exchanger housing 101 and is closer to the top of heat exchanger housing 101 than the first lubricating oil return port 105.

[0035] Through the above embodiments, the heat exchanger provided in this application can select either a first lubricating oil return port 105 or a second lubricating oil return port 106 with different height positions according to different refrigerant liquid levels in the heat exchanger shell cavity 101a. This ensures that the lubricating oil return port matches the refrigerant liquid level in the heat exchanger shell cavity 101a, avoiding the problem that when the operating conditions of the heat exchanger 1 change, i.e., the refrigerant liquid level inside the heat exchanger shell cavity 101a changes, the height position of the refrigerant liquid level and the lubricating oil return port will not match, resulting in the lubricating oil, which is mainly near the refrigerant liquid level surface, not being able to be recovered in time through the lubricating oil return port, thus affecting the operation of the refrigeration system.

[0036] It should be noted that, although Figure 1 The refrigerant inlet 102 and refrigerant outlet 103 of the heat exchanger 1 shown are arranged in a staggered manner, but this application is not limited to this. The arrangement of the refrigerant inlet 102 and refrigerant outlet 103 can be flexibly designed according to the different operating conditions and process designs of the heat exchanger 1, and all such arrangements should be included within the protection scope of this application.

[0037] In a preferred embodiment of this application, the distance L 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 housing 101 satisfies the following formula: The relationship.

[0038] Through the above embodiments, 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 of the heat exchanger housing 101 is set. This avoids the problem that the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 is too short, which would cause a large change in the refrigerant level inside the heat exchanger cavity 101a, making it impossible to match the change in refrigerant level even when switching between the first and second lubricating oil return ports 105 and 106. Simultaneously, the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 in the height direction along the side of the heat exchanger housing 101 is set. This avoids the problem that the distance between the first lubricating oil return port 105 and the second lubricating oil return port 106 is too far, which would cause the refrigerant level inside the heat exchanger cavity 101a to not drop (or rise) to reach the first lubricating oil return port 105 (or the second lubricating oil return port 106) when there is a large change in the refrigerant level, resulting in the connected lubricating oil return ports not being able to match the changes in the refrigerant level height inside the heat exchanger cavity 101a in a timely manner.

[0039] It should be noted that although the embodiments of this application use the first lubricating oil return port 105 and the second lubricating oil return port 106 as examples, this application is not limited to this. Depending on the operating conditions of different refrigeration systems 2, the model and parameters of heat exchangers 1, etc., adding more lubricating oil return ports should also be included within the scope of protection of this application.

[0040] <Second Implementation Method>

[0041] The heat exchanger 1 of the second embodiment of this application for absorbing heat and evaporating refrigerant in a refrigeration system is the same as the heat exchanger 1 of the above-described embodiment of this application for absorbing heat and evaporating refrigerant in a refrigeration system. They are described using the same name or symbols and are essentially the same content, so they will not be repeated here.

[0042] Figure 2 This is a schematic diagram of the structure of the heat exchanger 1 used for absorbing heat and evaporating refrigerant in the refrigeration system according to the second embodiment of this application. (See attached diagram.) Figure 2 As shown, unlike the heat exchanger 1 provided in the first embodiment of this application, the first lubricating oil return port 105 and the second lubricating oil return port 106 provided in the second embodiment of this application are located at different positions along the extension direction of the heat exchange tube bundle 104.

[0043] The refrigerant exchanges heat with the heat exchange medium within the heat exchange tube bundle 104 in the heat exchanger shell cavity 101a. The liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, in the flow direction of the heat exchange medium, the liquid refrigerant near the heat exchange medium inlet 1041 absorbs heat and evaporates into a gaseous refrigerant more fully, resulting in a lower liquid level. Conversely, the liquid refrigerant near the heat exchange medium outlet 1042, due to a smaller temperature difference, does not absorb heat and evaporate into a gaseous refrigerant as fully, resulting in a higher liquid level. This leads to differences in the liquid refrigerant level at different locations along the extension direction of the heat exchange tube bundle 104 within the heat exchanger 1. Generally, the liquid level near the heat exchange medium inlet 1041 is relatively lower, while the liquid level near the heat exchange medium outlet 1042 is relatively higher. Furthermore, along with the evaporation process of the liquid refrigerant, the liquid refrigerant level may fluctuate inside the heat exchanger cavity 101a along the extension direction of the heat exchange tube bundle 104.

[0044] In the above embodiments, the first lubricating oil return port 105 and the second lubricating oil return port 106 are located 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 housing 101 than the first lubricating oil return port 105. Preferably, the first lubricating oil return port 105 is located near the heat exchange medium inlet 1041 along the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is located near the heat exchange medium outlet 1042 along the extension direction of the heat exchange tube bundle 104. The second lubricating oil return port 106, which is closer to the top of the heat exchanger housing 101, corresponds to the position in the heat exchanger cavity 101a where the liquid level is higher and closer to the heat exchange medium outlet 1042, and the first lubricating oil return port 105 corresponds to the position in the heat exchanger cavity 101a where the liquid level is lower and closer to the heat exchange medium inlet 1041. This avoids the problem that when only one fixed lubricating oil return port is used, the lubricating oil may be unevenly distributed in the heat exchanger 1 or mainly stagnant on one side, which may affect the return efficiency.

[0045] It should be noted that although this embodiment is described by setting the first lubricating oil return port 105 and the second lubricating oil return port 106 at different positions along the extension direction of the heat exchange tube bundle 104, this application is not limited to this. The method of setting multiple lubricating oil return ports according to the extension direction of the heat exchange tube bundle 104 of the heat exchanger 1 and different liquid level heights should also be included in the protection scope of this application.

[0046] <Third Implementation Method>

[0047] The heat exchanger 1 of the third embodiment of this application for absorbing heat and evaporating refrigerant in a refrigeration system is described with the same name or symbol as the heat exchanger 1 of the above-described embodiments of this application for absorbing heat and evaporating refrigerant in a refrigeration system. They are all the same content and will not be described again here.

[0048] Figure 3 This is a schematic diagram of the structure of a heat exchanger used for absorbing heat and evaporating refrigerant in a refrigeration system according to the third embodiment of this application. (See attached diagram.) Figure 3 As shown, unlike the heat exchanger 1 provided in the above embodiments of this application, the first lubricating oil return port 105 and the second lubricating oil return port 106 provided in the third embodiment of this application are located at the same position in the side height direction of the heat exchanger housing 101. More preferably, the first lubricating oil return port 105 is located closer to the refrigerant outlet 103 along the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is located further away from the refrigerant outlet 103 along the extension direction of the heat exchange tube bundle 104.

[0049] The refrigerant exchanges heat with the heat exchange medium in the heat exchange tube bundle 104 within the heat exchanger shell cavity 101a. The liquid refrigerant absorbs heat and evaporates into a gaseous refrigerant. Therefore, under operating conditions, the refrigerant is always in a localized boiling and vaporizing state within the heat exchanger shell cavity 101a. The phenomenon of violent vaporization occurring simultaneously inside and on the surface of the liquid refrigerant may cause fluctuations in the liquid level of the refrigerant inside the heat exchanger shell cavity 101a.

[0050] When the refrigerant level inside the heat exchanger cavity 101a fluctuates significantly due to boiling and vaporization, for example, the refrigerant level near (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 the second lubricating oil return port 106). At this time, the lubricating oil mixed in the liquid refrigerant and floating on the surface of the liquid refrigerant can flow out of the heat exchanger 1 through the first lubricating oil return port 105 (or the second lubricating oil return port 106).

[0051] The first lubricating oil return port 105 and the second lubricating oil return port 106 are positioned at the same height along the side of the heat exchanger housing 101. The first lubricating oil return port 105 is positioned closer to the refrigerant outlet 103 along the extension direction of the heat exchange tube bundle 104, and the second lubricating oil return port 106 is positioned further away from the refrigerant outlet 103 along the extension direction of the heat exchange tube bundle 104. Based on the liquid level height in the heat exchanger cavity 101a, especially the liquid level fluctuations caused by the refrigerant being in a boiling state, the lubricating oil mixed in the liquid refrigerant and floating on the surface of the liquid refrigerant can flow out of the heat exchanger 1 through the first lubricating oil return port 105 or the second lubricating oil return port 106, which matches the liquid level height in the heat exchanger cavity 101a, for recovery. Through the above implementation method, even if the liquid level in the heat exchanger cavity 101a fluctuates frequently, the lubricating oil can still flow out through the first lubricating oil return port 105 or the second lubricating oil return port 106, which is highly matched, thereby improving the oil return efficiency of the refrigeration system and the stability of the refrigeration system operation.

[0052] It should be noted that this embodiment does not limit the 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 of the heat exchanger housing 101. The 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 of the heat exchanger housing 101, depending on the operating conditions of the refrigeration system, the amount of refrigerant charged in the refrigeration system, the model of the heat exchanger 1, etc., should all be included within the protection scope of this application.

[0053] <Fourth Implementation Method>

[0054] The fourth embodiment of this application provides a refrigeration system 2, which includes a compressor 202, a condenser 203 and an evaporator 204 connected in sequence through a refrigerant pipeline. The compressor 202 has a primary suction chamber 2021 on the compressor suction side, and the evaporator 204 is a heat exchanger 1 provided in the above embodiment for absorbing heat and evaporating refrigerant in the refrigeration system.

[0055] Figure 4 This is a schematic diagram of the module of the refrigeration system provided in the fourth embodiment of this application. (See attached diagram) Figure 4 As shown, the refrigeration system 2 provided in the fourth embodiment of this application 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.

[0056] The ejector has an input end, an output end, and a power end, with the input end connected to the ejector nozzle. For example... Figure 4 As shown, the input end of the first ejector 205 is connected to the first lubricating oil return port 105, the power end of the first ejector 205 is connected to the exhaust side of the compressor 202, the input end of the second ejector 206 is connected to the second lubricating oil return port 106, the power end of the second ejector 206 is connected to the exhaust side of the compressor 202, and the output ends of the first ejector 205 and the second ejector 206 are both connected to the suction side of the compressor 202.

[0057] The refrigeration system 2 provided in the fourth embodiment of this application also includes a lubricating oil tank 210 disposed at the lowest point of the refrigeration system 2. One end of the bypass pipe 2101 is connected to the lubricating oil tank 210, and the other end is connected to the first-stage suction chamber 2021 on the suction side of the compressor. The lubricating oil delivered to the first-stage suction chamber 2021 on the suction side of the compressor by 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 pipe 2021 under the action of gravity.

[0058] The lubricating oil tank 210 is also equipped with a lubricating oil pump 211. One end of the oil supply pipeline of the lubricating oil pump 211 is connected to the lubricating oil tank 2100, and the other end is connected to the lubricating oil inlet 2102 side of the compressor 202. When it is detected that the amount of lubricating oil in the compressor 202 has decreased or is lower than the required amount, the lubricating oil pump 211 provides driving force to the lubricating oil in the lubricating oil tank 210, so that the lubricating oil stored in the lubricating oil tank 210 is delivered to the compressor 202, preventing the operation of the compressor 202 from being affected by insufficient lubricating oil.

[0059] In the above-described embodiment, the high-pressure gaseous refrigerant discharged from the compressor 202 flows into the first ejector 205 or the second ejector 206 through the power end, and flows out at a relatively high speed through the nozzle of the first ejector 205 or the second ejector 206. The downstream of the nozzle is connected to the input end, forming a low-pressure area. This low-pressure area attracts the lubricating oil (which may contain some 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, which is connected to the input end of the first ejector 205 or the second ejector 206. After the lubricating oil and refrigerant are mixed through the first ejector 205 or the second ejector 206, they flow into the compressor 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 influence of gravity, the lubricating oil temporarily stored in the first-stage suction chamber 2021 on the suction side of the compressor 202 flows to the lubricating oil tank 210 through a bypass pipe 2021 that connects one end to the first-stage suction chamber 2021 on the suction side of the compressor 202 and the other end to the lubricating oil tank 210, thereby achieving oil recovery of the lubricating oil while achieving pressure balance in the refrigeration system 2.

[0060] Meanwhile, a portion of the high-temperature, high-pressure gaseous refrigerant flowing out from the exhaust side of the compressor 202 returns to the suction side of the compressor 202 after passing through the first ejector 205 or the second ejector 206, and mixes with the gaseous refrigerant flowing out from the evaporator 204, thereby increasing the pressure and temperature of the refrigerant flowing into the compressor 202 and improving the working efficiency of the compressor 202.

[0061] Thus, the 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 the driving force for the lubricating oil to flow to the first ejector 205 or the second ejector 206, thereby improving the lubricating oil recovery efficiency.

[0062] As a preferred embodiment of this application, a four-way valve 207 is also provided at the connection pipe between the input end of the first ejector 205 and the first lubricating oil return port 105, and at the connection pipe between the input end of the second ejector 206 and the second lubricating oil return port 106. The four valve ports of the four-way valve 207 can be connected to 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.

[0063] Therefore, by adjusting the switching of the four-way valve 207, the first lubricating oil return port 105 can be connected to 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 connected to the input end of the first ejector 205 or the input end of the second ejector 206.

[0064] Through the above implementation method, when the lubricating oil from the evaporator 204 is recovered through the first lubricating oil return port 105 (or the second lubricating oil return port 106), the first ejector 205 or the second ejector 206 that matches the fluid flow rate and pressure flowing out of the evaporator 204 through the first lubricating oil return port 105 (or the second lubricating oil return port 106) can be switched to improve the working efficiency and reliability of the ejector. It also reduces the possibility that using an ejector that does not match the actual fluid flow rate and pressure will cause a mismatch between the fluid suction force and the fluid flow rate flowing out of the evaporator 204, resulting in a mismatch in the drainage of the lubricating oil flowing out of the first lubricating oil return port 105 (or the second lubricating oil return port 106) and a decrease in oil recovery efficiency.

[0065] In a preferred embodiment of this application, based on 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 to the first ejector 205 and the second ejector 206, or simultaneously connect the second lubricating oil return port 106 to 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 connection to the matching first lubricating oil return port 105 or second lubricating oil return port 106 is switched according to the liquid level change inside the evaporator 204.

[0066] Through the above implementation method, when the fluid flow rate from the first lubricating oil return port 105 (or the second lubricating oil return port 106) is large, the four-way valve 207 simultaneously connects the first ejector 205 and the second ejector 205, so that the first ejector 205 and the second ejector 206 always work simultaneously. According to the liquid level in the evaporator 204, the matching first lubricating oil return port 105 or the second lubricating oil return port 106 can be switched to improve the oil recovery efficiency and reliability of the refrigeration system.

[0067] Figure 5 This is a schematic diagram of the module of the refrigeration system provided in the fourth embodiment of this application. (See attached diagram) Figure 5 As shown, in a further preferred embodiment, a first solenoid valve 208 is also provided on the pipeline connected to the power end of the first ejector 205, and a second solenoid valve 209 is also provided on the pipeline connected to the power end of the second ejector 206.

[0068] When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or the second lubricating oil return port 106) to the first ejector 205, the first solenoid valve 208 is opened and the second solenoid valve 209 is closed. At this time, a small portion of the refrigerant carrying lubricating oil flowing out of the compressor 202 flows into the first ejector 205 through the first solenoid valve 208, while the main portion flows into the condenser 203 to continue the refrigeration cycle. When the four-way valve 207 is switched to connect the first lubricating oil return port 105 (or the second lubricating oil return port 106) to the second ejector 206, the first solenoid valve 208 is closed and the second solenoid valve 209 is opened. At this time, a small portion of the refrigerant carrying lubricating oil flowing out of the compressor 202 flows into the second ejector 206 through the second solenoid valve 209, while the main portion flows into the condenser 203 to continue the refrigeration cycle.

[0069] 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 based on the fluid flow rate and pressure flowing out of the evaporator 204 from the first lubricating oil return port 105 (or the second lubricating oil return port 106). This improves the oil recovery efficiency of the refrigeration system 2 and avoids the high-temperature, high-pressure gaseous refrigerant flowing out of the compressor 202 returning to the suction side of the compressor 202 through the first ejector 205 and the second ejector 206, thus reducing the amount of refrigerant participating in the refrigeration cycle and lowering the heat exchange efficiency. Simultaneously, the first solenoid valve 208 or the second solenoid valve 209 corresponding to the first ejector 205 or the second ejector 206 that is not connected to the first lubricating oil return port 105 (or the second lubricating oil return port 106) is closed, solving the problem of unbalanced internal pressure difference in the unconnected first ejector 205 or the second ejector 206 and improving the reliability of the refrigeration system 2.

[0070] Although the embodiments of this application are described in the form of a first ejector 205, a second ejector 206 and corresponding first solenoid valves 208 and second solenoid valves 209, this application is not limited thereto. Any additional ejectors and corresponding solenoid valves provided according to the operating conditions of the refrigeration system 2, the model parameters of the evaporator 204, the model parameters of the ejectors, etc., should be included within the protection scope of this application.

[0071] <Fifth Implementation Method>

[0072] The refrigeration system 2 provided in the fifth embodiment of this application is the same as the refrigeration system 2 provided in the above embodiments of this application, and all those described using the same name or symbols are the same content, and will not be repeated here.

[0073] Figure 6 A schematic diagram of the refrigeration system provided in the fifth embodiment of this application is shown below. Figure 6As shown, the refrigeration system 2 provided in the fifth embodiment of this application further includes a lubricating oil heater 212 disposed in the lubricating oil tank 210.

[0074] The refrigerant stored in the lubricating oil in the lubricating oil tank 210 is heated by the lubricating oil heater 212 installed in the lubricating oil tank 210, which accelerates the evaporation of the refrigerant. The evaporated refrigerant returns to the first-stage suction chamber 2021 on the suction side of the compressor 202 through the bypass pipe 2101 to continue the refrigeration cycle. This avoids too much refrigerant remaining in the lubricating oil tank 210, which would cause the temperature of the lubricating oil stored in the lubricating oil tank 210 to be too low and affect its lubrication effect.

[0075] Preferably, a third ejector 213 is also provided in the pipeline connecting the lubricating oil tank 210 and the output end of the first ejector 205 or the second ejector 206. The input end of the third ejector 213 is connected to the first-stage suction chamber on the suction side of the compressor, the power end is connected to the exhaust side of the compressor, and the output end is connected to the lubricating oil tank.

[0076] In the above-described embodiment, the high-pressure gaseous refrigerant discharged from the compressor 202 flows into the third ejector 213 through the power end and flows out at a relatively high speed through the nozzle of the third ejector 213. The downstream of the nozzle connects to the input end, forming a low-pressure area. This low-pressure area attracts the oil-containing refrigerant temporarily stored in the primary suction chamber 2021 of the compressor 202 from the suction side, which is connected to 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. Thus, the bypass pipe 2101 and the third ejector 213 work together to achieve oil recovery of the lubricating oil, improving the oil recovery efficiency.

[0077] Preferably, a third solenoid valve 214 is also provided in the pipeline connecting the power end of the third ejector 213 and the exhaust side of the compressor 202. The opening and closing of the third solenoid valve 214 is controlled according to the fluid flow rate and pressure flowing out of the evaporator 204 through the first lubricating oil return port 105 (or the second lubricating oil return port 106). Specifically, when the fluid flow rate flowing out of the evaporator 204 through the first lubricating oil return port 105 (or the second lubricating oil return port 106) is small, the third solenoid valve 214 is closed. At this time, the third ejector 213 no longer attracts the oil-containing refrigerant in the first suction chamber 2021 of the compressor 202 by forming a low-pressure area. Instead, the input and output ends of the third ejector 213 form a bypass pipeline by gravity. The oil-containing refrigerant temporarily stored in the first suction chamber 2021 of the compressor 202 flows into the lubricating oil tank 210 through the input and output ends of the third ejector 213 under the action of gravity. When the fluid flow rate exiting the evaporator 204 through the first lubricating oil return port 105 (or the second lubricating oil return port 106) is relatively large, the third solenoid valve 214 is opened. At this time, the high-pressure gaseous refrigerant discharged by the compressor 202 flows into the third ejector 213 through the power end. The downstream of the nozzle is connected to the input end, forming a low-pressure area. This low-pressure area attracts the oil-containing refrigerant temporarily stored in the first-stage suction chamber 2021 of the suction side of the compressor 202, which is connected to the input end of the third ejector 213, thereby improving the oil recovery efficiency.

[0078] <Sixth Implementation Method>

[0079] This application also provides a control device for regulating and controlling the refrigeration system 2. Figure 7 A schematic diagram of the control device provided in the sixth embodiment of this application is shown below. Figure 7 As shown, the sixth embodiment of this application provides a control device 3 for adjusting and controlling any of the refrigeration systems 2 provided in the above embodiments. 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.

[0080] The evaporator liquid level detection module 31 detects and records the current liquid level height of the evaporator 204 in real time. When the current liquid level height detected by the evaporator liquid level detection module 31 is high, the four-way valve switching module 32 switches one end of the four-way valve 207 to the second lubricating oil return port 106, which is closer to the top of the evaporator 204. This allows the lubricating oil mixed in with the liquid refrigerant and floating on the surface of the liquid refrigerant to flow out of the evaporator 204 through the second lubricating oil return port 106 for recycling. When the current liquid level height detected by the evaporator liquid level detection module 31 is low, the four-way valve switching module 32 switches one end of the four-way valve 207 to the first lubricating oil return port 105, which is farther away from the top of the evaporator 204 in the vertical direction. This allows the lubricating oil mixed in with the liquid refrigerant and floating on the surface of the liquid refrigerant to flow out of the evaporator 204 through the first lubricating oil return port 105 for recycling.

[0081] At the same time, depending on the flow rate of lubricating oil flowing out of the evaporator 204, the other end of the four-way valve 207 is connected to either the first ejector 205 or the second ejector 206, which is more suitable in terms of model and flow rate.

[0082] The control device 3 also includes a solenoid valve control module 33. When the four-way valve switching module 32 controls the four-way valve 207 to connect to the first ejector 205, it controls the first solenoid valve 208 connected to the first ejector 205 to open and the second solenoid valve 209 connected to the second ejector 206 to close. When the four-way valve switching module 32 controls the four-way valve 207 to connect to the second ejector 206, it controls the second solenoid valve 209 connected to the second ejector 206 to open and the first solenoid valve 208 connected to the first ejector 205 to close.

[0083] Through the aforementioned control device 3, based on the current liquid level height 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 can be controlled more flexibly. When the liquid level height in the evaporator 204 changes, the four-way valve 207 can quickly switch to the first lubricating oil return port 105 or the second lubricating oil return port 106 that matches the liquid level height, thereby improving the oil recovery efficiency and operational stability of the refrigeration system 2.

[0084] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system, comprising: The heat exchanger shell surrounds and forms the heat exchanger cavity; A refrigerant inlet is provided with an opening in the heat exchanger housing, communicating with the heat exchanger housing cavity; The refrigerant outlet has an opening located at the top of the heat exchanger housing, connecting to the heat exchanger cavity; A heat exchange tube bundle is disposed within the shell cavity of the heat exchanger, and serves as the heat exchange medium through which the refrigerant within the heat exchanger shell cavity exchanges heat. Its characteristic is that it also includes, The first lubricating oil return port has an opening located on the side of the heat exchanger housing and connects to the heat exchanger housing cavity; The second lubricating oil return port is located on the side of the heat exchanger housing, closer to the top of the heat exchanger housing than the first lubricating oil return port.

2. The heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system as described in claim 1, characterized in that, The distance L between the first lubricating oil return port and the second lubricating oil return port in the height direction of the side surface of the heat exchanger housing, and the height H of the side surface of the heat exchanger housing, satisfy the following equation: The relationship.

3. The heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system as described in claim 1, characterized in that, The first lubricating oil return port and the second lubricating oil return port are located at different positions along the direction of the heat exchange tube bundle.

4. The heat exchanger for absorbing heat and evaporating refrigerant in a refrigeration system as described in claim 1, characterized in that, The first lubricating oil return port and the second lubricating oil return port are located at the same position in the height direction of the side of the heat exchanger housing.

5. A refrigeration system comprising a compressor, a condenser, and an evaporator, each having a suction-side primary suction chamber, connected sequentially via refrigerant piping, wherein the evaporator is a heat exchanger as described in any one of claims 1-4 for absorbing heat and evaporating refrigerant in the refrigeration system, characterized in that... It also includes, The first ejector has its input end connected to the first lubricating oil return port and its power end connected to the exhaust side of the compressor. The second ejector has its input end connected to the second lubricating oil return port and its power end connected to the exhaust side of the compressor.

6. The refrigeration system as described in claim 5, characterized in that, The output end of the first ejector is connected to the suction side of the compressor; The output end of the second ejector is connected to the suction side of the compressor.

7. The refrigeration system as described in claim 5, characterized in that, It also includes, The lubricating oil tank is connected to the output end of the first ejector and to the output end of the second ejector; A bypass pipeline is connected at one end to the lubricating oil tank and at the other end to the first-stage suction chamber on the suction side of the compressor.

8. The refrigeration system as described in claim 5, characterized in that, It also includes, The four-way valve is connected to 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, respectively. It can switch the connection between the first lubricating oil return port and the input end of the first ejector or the input end of the second ejector, and the connection between the second lubricating oil return port and the input end of the first ejector or the input end of the second ejector.

9. The refrigeration system as described in claim 5 or 8, characterized in that, It also includes, The first solenoid valve is installed in the pipeline connected to the power end of the first ejector; The second solenoid valve is installed in the pipeline connected to the power end of the second ejector.

10. The refrigeration system as described in claim 7, characterized in that, It also includes, A lubricating oil pump is installed inside the lubricating oil tank and connects the lubricating oil tank to the oil supply line at the lubricating oil inlet of the compressor.

11. The refrigeration system as described in claim 10, characterized in that, Also includes: The third ejector has its input end connected to the first-stage suction chamber on the suction side of the compressor, its power end connected to the discharge side of the compressor, and its output end connected to the lubricating oil tank.

12. The refrigeration system as described in claim 11, characterized in that, Also includes: A lubricating oil heater is installed in the lubricating oil tank.

13. A control device for regulating and controlling the refrigeration system as described in claim 9, characterized in that, include: Evaporator liquid level detection module, which detects and records the current liquid level height of the evaporator in real time; The four-way valve switching module switches one end of the four-way valve to the first lubricating oil return port or the second lubricating oil return port, and the other end to the first ejector or the second ejector, based on the current liquid level height of the evaporator detected by the evaporator liquid level detection module. The solenoid valve control module controls the first solenoid valve to open and the second solenoid valve to close when the four-way valve is switched to the first ejector, and controls the second solenoid valve to open and the first solenoid valve to close when the four-way valve is switched to the second ejector.

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