Refrigeration system

Abstract

The utility model relates to a refrigerating system which comprises a first refrigerating module which comprises a first compressor, a condenser, a first expansion valve and a first evaporator which are sequentially communicated to form a first closed loop; the second refrigeration module comprises a second compressor, the first evaporator, a second expansion valve and a second evaporator which are sequentially communicated to form a second closed loop; the second closed loop comprises a first pipeline arranged between the output end of the second expansion valve and the input end of the second evaporator; the flash evaporator is arranged on the first closed loop, an input port of the flash evaporator is communicated with the output end of the condenser, and a liquid outlet of the flash evaporator is communicated with the input end of the first evaporator; the heat exchange pipeline is communicated between an air outlet of the flash evaporator and the input end of the first compressor, and a refrigerant in the heat exchange pipeline exchanges heat with a refrigerant in the first pipeline through the first heat exchanger.

Description

Technical Field

[0001] The utility model relates to the technical field of temperature control, in particular to a refrigeration system. Background Art

[0002] The test equipment for electronic components is equipped with a temperature control system, which includes a refrigeration system and a heating system. When testing electronic components, the temperature of the electronic components is controlled by the cold and hot confrontation between the refrigeration system and the heating system to ensure the accuracy of the test results. Among them, the two-stage compression cascade refrigeration system is more common.

[0003] The two-stage compression cascade refrigeration system includes a high-temperature refrigeration module and a low-temperature refrigeration module, and the low-temperature refrigeration module ultimately provides medium-temperature or low-temperature refrigerant. The refrigerant provided by the low-temperature refrigeration module exchanges heat with the electronic components through the load end, so that the electronic components are kept at the target temperature.

[0004] When the load side needs a higher evaporation temperature to exchange heat with electronic components, a bypass line is drawn out through the exhaust end of the compressor of the low-temperature refrigeration module. The refrigerant in the bypass line is mixed with the refrigerant in the main cycle after throttling and cooling by the expansion valve. The mixing ratio of the two refrigerants is adjusted to control the evaporation temperature output to the load side. However, in this way, the mixing ratio of the refrigerants is not easy to control, and the cycle of adjusting to the target temperature is long. At the same time, after the bypass line is separated, it is easy to cause insufficient refrigeration capacity of the main cycle, which leads to unstable temperature control. Utility Model Content

[0005] Based on this, it is necessary to provide a refrigeration system that can improve the above problems.

[0006] A refrigeration system, comprising:

[0007] The first refrigeration module comprises a first compressor, a condenser, a first expansion valve and a first evaporator which are sequentially connected to form a first closed loop;

[0008] The second refrigeration module comprises a second compressor, the first evaporator, a second expansion valve and a second evaporator which are sequentially connected to form a second closed loop; the second closed loop comprises a first pipeline arranged between an output end of the second expansion valve and an input end of the second evaporator;

[0009] A first heat exchanger, a heat exchange pipeline and a flash evaporator arranged on the first closed loop, the input port of the flash evaporator is connected to the output end of the condenser, and the liquid outlet of the flash evaporator is connected to the input end of the first evaporator; the heat exchange pipeline is connected between the gas outlet of the flash evaporator and the input end of the first compressor, and the refrigerant in the heat exchange pipeline exchanges heat with the refrigerant in the first pipeline through the first heat exchanger.

[0010] In the above refrigeration system, the refrigerant in the condenser flows to the flash evaporator for flash evaporation and is divided into two paths. One path flows to the first evaporator through the liquid outlet of the flash evaporator, and flows to the first compressor through the first evaporator, and the other path flows to the heat exchange pipeline through the gas outlet of the flash evaporator. The refrigerant flowing to the heat exchange pipeline can exchange heat with the refrigerant in the first pipeline through the first heat exchanger to increase the temperature of the refrigerant flowing to the second evaporator, and finally flows to the first compressor through the heat exchange pipeline. In this way, when the second evaporator (the load end for heat exchange with the electronic components) needs a higher evaporation temperature to exchange heat with the electronic components, the refrigerant after flash evaporation in the flash evaporator is controlled to flow to the heat exchange pipeline through its gas outlet, and exchange heat with the refrigerant in the first pipeline through the first heat exchanger to increase the temperature of the refrigerant flowing to the second evaporator. Compared with the method in the prior art of leading a bypass line from the exhaust end of the compressor to increase the temperature of the refrigerant flowing to the second evaporator, the temperature of the refrigerant flashed by the flash evaporator is easy to control, making it easy to control the temperature of the refrigerant flowing to the second evaporator, shortening the period of regulation to the target temperature; at the same time, the liquid separation branch of the second refrigeration module is reduced, solving the problem of insufficient cooling capacity of the second refrigeration module (low-temperature refrigeration module), making the system temperature control stable.

[0011] In one embodiment, the input port of the flash evaporator is communicated with the output end of the first expansion valve, and the liquid outlet of the flash evaporator is communicated with the input end of the first evaporator.

[0012] In one of the embodiments, the refrigeration system further includes a control valve, which is disposed on the heat exchange pipeline to control the on-off of the heat exchange pipeline.

[0013] In one embodiment, the control valve is disposed between the flash evaporator and the first heat exchanger.

[0014] In one embodiment, the refrigeration system further includes a temperature reduction mechanism, and the temperature reduction mechanism is used to reduce the return air temperature of the refrigerant flowing to the second compressor.

[0015] In one embodiment, the cooling mechanism includes a bypass branch and a third expansion valve, the two ends of the bypass branch are respectively connected to the output end and the input end of the second compressor, and the third expansion valve is arranged on the bypass branch;

[0016] The cooling mechanism also includes a second heat exchanger, the bypass branch includes a first part of the bypass branch located at the output end of the second compressor and the input end of the third expansion valve, the first closed loop includes a second pipeline arranged at the output end of the first evaporator and the input end of the first compressor, and the refrigerant in the first part of the bypass branch exchanges heat with the refrigerant in the second pipeline through the second heat exchanger.

[0017] In one embodiment, the refrigeration system also includes a gas-liquid separator arranged on the second closed loop, the input port of the gas-liquid separator is connected to the output end of the second evaporator, the output port of the gas-liquid separator is connected to the input end of the second compressor, and the bypass branch is connected to the input end of the second compressor through the gas-liquid separator.

[0018] In one embodiment, the refrigeration system further includes a fourth expansion valve, and the fourth expansion valve is disposed on the second pipeline.

[0019] In one embodiment, the fourth expansion valve is disposed on a portion of the second pipeline located between an output end of the first evaporator and an input end of the second heat exchanger.

[0020] In one embodiment, the refrigeration system also includes an oil separator and a throttling device. The oil separator is arranged on the second closed loop and is located between the output end of the second compressor and the input end of the first evaporator. The two ends of the throttling device are respectively connected to the output end of the oil separator and the input end of the second compressor; the lubricating oil separated by the oil separator is throttled by the throttling device and then circuited to the input end of the second compressor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of a refrigeration system provided in one embodiment of the present application;

[0022] Figure 2 A schematic diagram of a refrigeration system provided in another embodiment of the present application;

[0023] Figure 3 A schematic diagram of a refrigeration system provided in yet another embodiment of the present application;

[0024] Figure 4 A schematic diagram of a refrigeration system provided in yet another embodiment of the present application.

[0025] Description of reference numerals:

[0026] 100. refrigeration system; 10. first refrigeration module; 11. first compressor; 12. condenser; 13. first expansion valve; 14. first evaporator; 15. second pipeline; 20. second refrigeration module; 21. second compressor; 22. second expansion valve; 23. second evaporator; 24. first pipeline; 30. cooling mechanism; 40. flash evaporator; 41. inlet; 42. liquid outlet; 43. gas outlet; 50. heat exchange pipeline; 60. first heat exchanger; 70. control valve; 81. bypass branch; 82. third expansion valve; 83. second heat exchanger; 90. gas-liquid separator; 110. fourth expansion valve; 120. oil separator; 130. throttling device. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0028] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0032] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0033] See also Figure 1 In one embodiment of the present application, a refrigeration system 100 is provided for controlling the temperature of electronic components. Specifically, the electronic components are chips, and the refrigeration system 100 is used to control the temperature of the chips. Of course, in other embodiments, the types of electronic components used for temperature control by the refrigeration system 100 are not limited.

[0034] The refrigeration system 100 includes a first refrigeration module 10 , which includes a first compressor 11 , a condenser 12 , a first expansion valve 13 , and a first evaporator 14 which are sequentially connected to form a first closed loop.

[0035] When the first refrigeration module 10 is working, the first compressor 11 inhales the high-temperature, low-pressure refrigerant gas output from the output end of the first evaporator 14, compresses the refrigerant into a high-temperature, high-pressure refrigerant gas, and discharges it to the condenser 12 from the exhaust end (output end) of the first compressor 11. When the refrigerant passes through the condenser 12, it is condensed into a medium-temperature, high-pressure refrigerant liquid by the condenser 12, and is expanded and reduced in pressure by the first expansion valve 13 to be a low-temperature, low-pressure refrigerant liquid, and finally input into the first evaporator 14 again from the input end of the first evaporator 14. When the low-temperature, low-pressure liquid refrigerant enters the first evaporator 14, it can exchange heat with other structures, thereby controlling the temperature of other structures. The refrigerant after heat exchange enters the first compressor 11 again from the output end of the first evaporator 14, and the cycle repeats.

[0036] The refrigeration system 100 also includes a second refrigeration module 20, which includes a second compressor 21, a first evaporator 14, a second expansion valve 22 and a second evaporator 23 that are sequentially connected to form a second closed loop. That is, the first evaporator 14 serves as the evaporator of the first refrigeration module 10, and as the condenser of the second refrigeration module 20, the first evaporator 14 is also called an evaporative condenser. At this time, the first refrigeration module 10 is a high-temperature refrigeration module, and the second refrigeration module 20 is a low-temperature refrigeration module. It should be noted that the evaporative condenser has two input ends and two output ends, and the two input ends correspond to the two output ends one by one and are connected to each other. When the evaporative condenser serves as the evaporator of the first refrigeration module 10, the corresponding input end and output end are respectively connected to the output end of the first expansion valve 13 and the input end of the first compressor 11. When the evaporative condenser serves as the condenser of the second refrigeration module 20, the corresponding input end and output end are respectively connected to the output end of the second compressor 21 and the input end of the second expansion valve 22.

[0037] Specifically, the first expansion valve 13 and the second expansion valve 22 are both electronic expansion valves to facilitate the expansion and pressure reduction of the refrigerant.

[0038] When the second refrigeration module 20 is working, the second compressor 21 sucks the high-temperature and low-pressure refrigerant gas output from the output end of the second evaporator 23, compresses the refrigerant into a high-temperature and high-pressure refrigerant gas, and discharges it from the output end of the second compressor 21 to the first evaporator 14. When the refrigerant passes through the first evaporator 14, it exchanges heat with the refrigerant of the first refrigeration module 10, is condensed into a medium-temperature and high-pressure refrigerant liquid by the first evaporator 14, and is expanded and reduced in pressure by the second expansion valve 22 to be a low-temperature and low-pressure refrigerant liquid, and finally enters the second evaporator 23 again from the input end of the second evaporator 23. When the low-temperature and low-pressure liquid refrigerant enters the second evaporator 23, it can exchange heat with the electronic components to control the temperature of the electronic components. The refrigerant after heat exchange enters the second compressor 21 again from the output end of the second evaporator 23, and the cycle repeats.

[0039] See also Figure 2 , the refrigeration system 100 further includes a cooling mechanism 30, which is used to cool the condenser 12 of the first refrigeration module 10. In some embodiments, the cooling mechanism 30 is a water chiller. It is conceivable that in other embodiments, the cooling mechanism 30 includes at least one third refrigeration module, and the third refrigeration module is arranged in a manner similar to the first refrigeration module 10 or the second refrigeration module 20. In this case, the refrigeration system 100 will form a three-stage or multi-stage refrigeration system. It is conceivable that when the refrigeration system 100 only includes the first refrigeration module 10 and the second refrigeration module 20, the refrigeration system 100 is a two-stage compression cascade refrigeration system.

[0040] Continue reading Figure 1 and Figure 2 The refrigeration system 100 further includes a flash evaporator 40, which is arranged on the first closed loop. Flash evaporation means that a high-pressure saturated liquid enters a relatively low-pressure container, and due to a sudden drop in pressure, the saturated liquid becomes a saturated vapor and a saturated liquid under a portion of the container pressure.

[0041] The flash evaporator 40 has an input port 41, a liquid outlet 42 and a gas outlet 43. The input port 41 of the flash evaporator 40 is connected to the output end of the condenser 12, and the liquid outlet 42 of the flash evaporator 40 is connected to the input end of the first evaporator 14. The second closed loop includes a first pipeline 24 provided between the output end of the second expansion valve 22 and the input end of the second evaporator 23. The refrigeration system 100 also includes a heat exchange pipeline 50 and a first heat exchanger 60. The heat exchange pipeline 50 is connected between the gas outlet 43 of the flash evaporator 40 and the input end of the first compressor 11. The refrigerant in the heat exchange pipeline 50 exchanges heat with the refrigerant in the first pipeline 24 through the first heat exchanger 60.

[0042] According to the above arrangement, the refrigerant of the condenser 12 flows to the flash evaporator 40 for flash evaporation and is divided into two paths. One path flows to the first evaporator 14 through the liquid outlet 42 of the flash evaporator 40, and flows to the first compressor 11 through the first evaporator 14, and the other path flows to the heat exchange pipeline 50 through the gas outlet 43 of the flash evaporator 40. The refrigerant flowing to the heat exchange pipeline 50 can exchange heat with the refrigerant in the first pipeline 24 through the first heat exchanger 60 to increase the temperature of the refrigerant flowing to the second evaporator 23, and finally flows to the first compressor 11 through the heat exchange pipeline 50. In this way, when the second evaporator 23 (the load end for heat exchange with the electronic components) needs a higher evaporation temperature to exchange heat with the electronic components, the refrigerant after flash evaporation in the flash evaporator 40 is controlled to flow to the heat exchange pipeline 50 through its gas outlet 43, and exchange heat with the refrigerant in the first pipeline 24 through the first heat exchanger 60 to increase the temperature of the refrigerant flowing to the second evaporator 23. Compared with the method in the prior art of leading a bypass line from the exhaust end of the compressor to increase the temperature of the refrigerant flowing to the second evaporator 23, the temperature of the refrigerant flashed by the flash evaporator 40 is easy to control, so that the temperature of the refrigerant flowing to the second evaporator 23 is easy to control, and the period of regulation to the target temperature is shortened; at the same time, the liquid separation branch of the second refrigeration module 20 is also reduced, which solves the problem of insufficient cooling capacity of the second refrigeration module 20 (low-temperature refrigeration module), making the system temperature control stable.

[0043] It should be noted here that when the refrigerant after flash vaporization flows to the heat exchange pipeline 50 through the air outlet 43 of the flash evaporator 40 to increase the evaporation temperature of the refrigerant flowing to the second evaporator 23, the refrigerant after flash vaporization also flows to the first evaporator 14 through the liquid outlet 42 of the flash evaporator 40, so that the first refrigeration module 10 and the second refrigeration module 20 are always in a heat exchange state, ensuring the stable operation of the system.

[0044] In some embodiments, the input port 41 of the flash evaporator 40 is connected to the output end of the first expansion valve 13, and the liquid outlet 42 of the flash evaporator 40 is connected to the input end of the first evaporator 14. When the refrigerant is expanded and depressurized by the first expansion valve 13, it is transformed from a medium-temperature and high-pressure liquid to a low-temperature and low-pressure liquid. The input port 41 of the flash evaporator 40 is directly connected to the output end of the first expansion valve 13. At this time, the refrigerant expanded by the first expansion valve 13 flows to the flash evaporator 40, which can provide the amount of gas formed after flash evaporation in the flash evaporator 40, so that more gaseous refrigerant enters the heat exchange pipeline 50, thereby increasing the evaporation temperature of the refrigerant flowing to the second evaporator 23.

[0045] It is conceivable that in some other embodiments, continue to refer to Figure 2 The input port 41 of the flash evaporator 40 may also be arranged to be directly connected to the output end of the condenser 12, which is not limited here.

[0046] In some embodiments, the refrigeration system 100 further includes a control valve 70, which is disposed on the heat exchange pipeline 50 to control the on-off of the heat exchange pipeline 50. Specifically, the control valve 70 is a solenoid valve. In this way, when the evaporation temperature output by the refrigeration system 100 is low temperature (such as below -40°C), the control valve 70 is closed, and at this time, only the main circuit circulation (circulation in the first closed loop) of the first refrigeration module 10 provides cold capacity for the second refrigeration module 20 circulation. When the evaporation temperature output by the refrigeration system 100 is high temperature (such as above -40°C), the control valve 70 is opened, and the medium-temperature medium-pressure refrigerant discharged from the air outlet 43 of the flash evaporator 40 exchanges heat with the main circuit circulation (circulation in the second closed loop) refrigerant of the second refrigeration module 20 through the first heat exchanger 60, thereby increasing the evaporation temperature of the refrigerant going to the second evaporator 23, so that the evaporation temperature reaches the target temperature.

[0047] Further reading Figure 1 and Figure 2 The control valve 70 is disposed between the flash evaporator 40 and the first heat exchanger 60. In this way, the refrigerant flowing into the heat exchange pipeline 50 after flash evaporation in the flash evaporator 40 can be controlled. Figure 3 The control valve 70 may also be disposed between the first heat exchanger 60 and the first compressor 11, which is not limited here.

[0048] In some embodiments, the refrigeration system 100 further includes a cooling mechanism for reducing the return air temperature of the refrigerant flowing to the second compressor 21 to avoid a system failure caused by the return air temperature of the second compressor 21 being too high and thus causing the system to fail to operate.

[0049] In some specific implementations, see Figure 4The cooling mechanism includes a bypass branch 81 and a third expansion valve 82. The two ends of the bypass branch 81 are respectively connected to the output end and the input end of the second compressor 21. The third expansion valve 82 is arranged on the bypass branch 81. The cooling mechanism also includes a second heat exchanger 83. The bypass branch 81 includes a first part of the bypass branch located at the output end of the second compressor 21 and the input end of the third expansion valve 82. The first closed loop includes a second pipeline 15 provided at the output end of the first evaporator 14 and the input end of the first compressor 11. The refrigerant in the first part of the bypass branch exchanges heat with the refrigerant in the second pipeline 15 through the second heat exchanger 83.

[0050] According to the above arrangement, the refrigerant output from the output end of the second compressor 21 is divided into two paths, one path flows to the second closed loop as the main path circulation, and the other path flows to the bypass branch 81 as the auxiliary path circulation. Among them, in the auxiliary path circulation, the high-temperature and high-pressure refrigerant gas output from the output end of the second compressor 21 enters the second heat exchanger 83, exchanges heat with the refrigerant in the second pipeline 15 to form a medium-temperature and high-pressure refrigerant liquid, expands and reduces the pressure to a low-temperature and low-pressure refrigerant through the third expansion valve 82, and finally flows to the input end (return gas end) of the second compressor 21 to reduce the return gas temperature of the second compressor 21. In this way, no matter whether the evaporation temperature output by the refrigeration system 100 is low temperature or high temperature, the refrigerant in the auxiliary path circulation can play the purpose of adjusting the return gas temperature of the second compressor 21, and avoid the return gas temperature of the second compressor 21 being too high and causing system failure.

[0051] Furthermore, the refrigeration system 100 also includes a gas-liquid separator 90 arranged on the second closed loop, the input port 41 of the gas-liquid separator 90 is connected to the output end of the second evaporator 23, the output port of the gas-liquid separator 90 is connected to the input end of the second compressor 21, and the bypass branch 81 is connected to the input end of the second compressor 21 through the gas-liquid separator 90. With such arrangement, on the one hand, the low-temperature and low-pressure refrigerant after throttling by the third expansion valve 82 and the high-temperature and low-pressure refrigerant output from the output end of the second evaporator 23 can be fully mixed in the gas-liquid separator 90, so as to reduce the return gas temperature of the second compressor 21; on the other hand, the gas-liquid separator 90 has a gas-liquid separation function, and can also prevent the return gas of the second compressor 21 from carrying liquid; on the other hand, the refrigerant after expansion by the third expansion valve 82 flows to the gas-liquid separator 90, and at this time, the gas-liquid separator 90 can also serve as an evaporator of the auxiliary circuit circulation, so that the low-temperature and low-pressure liquid refrigerant is converted into other high-temperature and low-pressure refrigerants to enter the second compressor 21, avoiding the risk of liquid hammer caused by the refrigerant after throttling by the third expansion valve 82 directly entering the second compressor 21. At the same time, the gas-liquid separator 90 of appropriate size can also replace the expansion tank, and is used to store gaseous refrigerant when the system is static to prevent the system pressure from being too high.

[0052] In some embodiments, the refrigeration system 100 further includes a fourth expansion valve 110, which is disposed on the second pipeline 15. Specifically, the third expansion valve 82 and the fourth expansion valve 110 are also electronic expansion valves.

[0053] The fourth expansion valve 110 can expand and reduce the pressure of the refrigerant in the second pipeline 15, so as to avoid the refrigerant in the second pipeline 15 and the refrigerant in the bypass branch 81 from having an excessively high temperature after heat exchange through the second heat exchanger 83. That is, the setting of the fourth expansion valve 110 can reduce the return air temperature of the first compressor 11, so as to avoid the situation where the return air temperature of the first compressor 11 is too high and causes system failure.

[0054] Further reading Figure 4 The fourth expansion valve 110 is arranged on a portion of the second pipeline 15 located at the output end of the first evaporator 14 and the input end of the second heat exchanger 83. In this arrangement, the refrigerant output from the output end of the first evaporator 14 first passes through the fourth expansion valve 110 for secondary throttling before flowing to the second heat exchanger 83. The temperature of the refrigerant is reduced when passing through the fourth expansion valve 110, so that when passing through the second heat exchanger 83, it exchanges heat with the refrigerant in the bypass branch 81 to reduce the temperature of the refrigerant in the bypass branch 81.

[0055] It is understandable that, in some other embodiments, the fourth expansion valve 110 may also be disposed on the second pipeline 15 located between the output end of the second heat exchanger 83 and the input end of the first compressor 11, which is not limited here.

[0056] In some embodiments, see Figure 4 , the refrigeration system 100 further includes an oil separator 120 and a throttle 130. The oil separator 120 is arranged on the second closed loop and is located between the output end of the second compressor 21 and the input end of the first evaporator 14, and the two ends of the throttle 130 are respectively connected to the output end of the oil separator 120 and the input end of the second compressor 21. The lubricating oil separated by the oil separator 120 is throttled by the throttle 130 and then returns to the input end of the second compressor 21. In this way, the refrigerant output from the output end of the second compressor 21 passes through the oil separator 120, and the lubricating oil separated from the oil separator 120 is throttled by the throttle 130, and then flows to the second compressor 21 together after merging with the refrigerant in the suction pipe.

[0057] In some embodiments, the throttling element 130 is a capillary tube. It is understood that in some other embodiments, the throttling element 130 may also be an electronic expansion valve, which is not limited here.

[0058] The refrigeration system 100 provided by the present application is described in more detail below with reference to a specific embodiment:

[0059] Continue reading Figure 4The refrigeration system 100 includes a first refrigeration module 10 and a second refrigeration module 20, and the first refrigeration module 10 and the second refrigeration module 20 together form a two-stage compression cascade refrigeration system 100. The first refrigeration module 10 includes a first compressor 11, a condenser 12, a first expansion valve 13 and a first evaporator 14 that are sequentially connected to form a first closed loop. The second refrigeration module 20 includes a second compressor 21, a first evaporator 14, a second expansion valve 22 and a second evaporator 23 that are sequentially connected to form a second closed loop. Among them, the first evaporator 14 is an evaporative condenser.

[0060] The refrigeration system 100 further includes a flash evaporator 40, a heat exchange pipeline 50, a first heat exchanger 60 and a control valve 70. The input port 41 of the flash evaporator 40 is connected to the output end of the first expansion valve 13, the liquid outlet 42 of the flash evaporator 40 is connected to the input end of the first evaporator 14, the gas outlet 43 of the flash evaporator 40 is connected to one end of the heat exchange pipeline 50, and the other end of the heat exchange pipeline 50 is connected to the input end of the first compressor 11. The second closed loop includes a first pipeline 24 provided between the output end of the second expansion valve 22 and the input end of the second evaporator 23. The heat exchange pipeline 50 is thermally coupled to the first pipeline 24 through the first heat exchanger 60, and the control valve 70 is provided between the flash evaporator 40 and the first heat exchanger 60.

[0061] The circulation of the refrigerant in the first closed loop is the main circulation of the first refrigeration module 10 .

[0062] The refrigeration system 100 further includes a cooling mechanism, which includes a bypass branch 81, a second heat exchanger 83 and a third expansion valve 82. The refrigeration system 100 further includes a gas-liquid separator 90 and a fourth expansion valve 110. The gas-liquid separator 90 is arranged between the output end of the second evaporator 23 and the input end of the second compressor 21, one end of the bypass branch 81 is connected to the output end of the second compressor 21, and the other end is connected to the gas-liquid separator 90, and the third expansion valve 82 is arranged on the bypass branch 81. The first closed loop includes a second pipeline 15 located at the output end of the first evaporator 14 and the input end of the first compressor 11, and the bypass branch 81 is thermally coupled to the second pipeline 15 through the second heat exchanger 83. The fourth expansion valve 110 is arranged on the second pipeline 15 and is located between the first evaporator 14 and the second heat exchanger 83.

[0063] The refrigerant circulates in the second closed loop as the main circuit circulation of the second refrigeration module 20 , and circulates in the bypass branch 81 as the auxiliary circuit circulation of the second refrigeration module 20 .

[0064] The working principle of the above refrigeration system 100 is as follows:

[0065] When the evaporation temperature output by the refrigeration system 100 is low temperature (such as below -40°C), the control valve 70 is closed, and the main circulation in the first refrigeration module 10 provides cooling capacity for the second refrigeration module 20, and the cooling capacity of the first evaporator 14 is regulated by controlling the first expansion valve 13 and the fourth expansion valve 110. In the main circulation of the second refrigeration module 20, the cooling capacity for the second evaporator 23 is controlled by controlling the second expansion valve 22, and the first heat exchanger 60 does not play a heat exchange role at this time. The auxiliary circulation adjusts the return air temperature of the second compressor 21 only when the heat exchange amount of the second evaporator 23 is very large, so as to avoid the situation in which the exhaust temperature / pressure of the second compressor 21 exceeds the warning range under special circumstances, causing frequent shutdown of the whole machine.

[0066] When the evaporation temperature output by the refrigeration system 100 is high temperature (such as above -40°C), the control valve 70 opens, and the medium-temperature and medium-pressure refrigerant coming out of the flash evaporator 40 exchanges heat with the refrigerant in the main circulation of the second refrigeration module 20 through the first heat exchanger 60, thereby increasing the evaporation temperature to the second evaporator 23 so that the evaporation temperature reaches the target temperature. At the same time, the third expansion valve 82 is always in a regulating state, and the refrigerant in the main circulation is reasonably distributed to adjust the refrigeration capacity of the main circulation to the second evaporator 23, which is convenient for the temperature control of the second evaporator 23. The low-temperature and low-pressure refrigerant after throttling by the third expansion valve 82 is mixed with the high-temperature and low-pressure return air refrigerant in the gas-liquid separator 90, thereby reducing the return air temperature of the second compressor 21, and avoiding the situation where the system exhaust temperature / pressure is too high and cannot work normally.

[0067] It should be noted here that the control method of each expansion valve in the above system can adopt control methods such as PID control and fuzzy adaptive control, which have high control accuracy and small adjustment margin, and can ensure stable operation of the system.

[0068] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0069] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A refrigeration system, characterized in that: include: A first refrigeration module (10) comprises a first compressor (11), a condenser (12), a first expansion valve (13) and a first evaporator (14) which are connected in sequence to form a first closed loop; The second refrigeration module (20) comprises a second compressor (21), the first evaporator (14), a second expansion valve (22) and a second evaporator (23) which are sequentially connected to form a second closed loop; the second closed loop comprises a first pipeline (24) provided between an output end of the second expansion valve (22) and an input end of the second evaporator (23); A first heat exchanger (60), a heat exchange pipeline (50) and a flash evaporator (40) arranged on the first closed loop, wherein the input port (41) of the flash evaporator (40) is connected to the output end of the condenser (12), and the liquid outlet (42) of the flash evaporator (40) is connected to the input end of the first evaporator (14); the heat exchange pipeline (50) is connected between the gas outlet (43) of the flash evaporator (40) and the input end of the first compressor (11), and the refrigerant in the heat exchange pipeline (50) exchanges heat with the refrigerant in the first pipeline (24) through the first heat exchanger (60).

2. The refrigeration system according to claim 1, characterized in that: The input port (41) of the flash evaporator (40) is in communication with the output end of the first expansion valve (13), and the liquid outlet (42) of the flash evaporator (40) is in communication with the input end of the first evaporator (14).

3. The refrigeration system according to claim 1, characterized in that: The refrigeration system further comprises a control valve (70), wherein the control valve (70) is arranged on the heat exchange pipeline (50) and is used to control the on-off of the heat exchange pipeline (50).

4. The refrigeration system according to claim 3, characterized in that: The control valve (70) is disposed between the flash evaporator (40) and the first heat exchanger (60).

5. The refrigeration system according to claim 1, characterized in that: The refrigeration system further comprises a temperature reduction mechanism, which is used to reduce the return air temperature of the refrigerant flowing to the second compressor (21).

6. The refrigeration system according to claim 5, characterized in that: The cooling mechanism comprises a bypass branch (81) and a third expansion valve (82), wherein two ends of the bypass branch (81) are respectively connected to the output end and the input end of the second compressor (21), and the third expansion valve (82) is arranged on the bypass branch (81); The cooling mechanism also includes a second heat exchanger (83), the bypass branch (81) includes a first part of the bypass branch located at the output end of the second compressor (21) and the input end of the third expansion valve (82), the first closed loop includes a second pipeline (15) arranged at the output end of the first evaporator (14) and the input end of the first compressor (11), and the refrigerant in the first part of the bypass branch exchanges heat with the refrigerant in the second pipeline (15) through the second heat exchanger (83).

7. The refrigeration system according to claim 6, characterized in that: The refrigeration system further comprises a gas-liquid separator (90) arranged on the second closed loop, the input port (41) of the gas-liquid separator (90) being connected to the output end of the second evaporator (23), the output port of the gas-liquid separator (90) being connected to the input end of the second compressor (21), and the bypass branch (81) being connected to the input end of the second compressor (21) through the gas-liquid separator (90).

8. The refrigeration system according to claim 6, characterized in that: The refrigeration system further comprises a fourth expansion valve (110), wherein the fourth expansion valve (110) is arranged on the second pipeline (15).

9. The refrigeration system according to claim 8, characterized in that: The fourth expansion valve (110) is disposed on a portion of the second pipeline (15) located between the output end of the first evaporator (14) and the input end of the second heat exchanger (83).

10. The refrigeration system according to claim 1, characterized in that: The refrigeration system further comprises an oil separator (120) and a throttling device (130); the oil separator (120) is arranged on the second closed loop and is located between the output end of the second compressor (21) and the input end of the first evaporator (14); two ends of the throttling device (130) are respectively connected to the output end of the oil separator (120) and the input end of the second compressor (21); the lubricating oil separated by the oil separator (120) is throttled by the throttling device (130) and then circulated to the input end of the second compressor (21).

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