CN220062229U - Refrigerating system and sorting test equipment - Google Patents

Abstract

The utility model relates to a refrigerating system, sorting test equipment and a refrigerating method, comprising the following steps: the first refrigerating module comprises a first compressor, a first condenser, a first expansion valve and a first evaporator which are sequentially communicated to form a first closed loop; a coolant loop thermally coupled to the first closed loop through a first condenser; the first heat exchanger and the first pipeline are connected with one end of the first pipeline, the exhaust end of the first compressor is connected with one end of the first pipeline, and the other end of the first pipeline is connected with the input end of the first evaporator; the first pipeline is thermally coupled with the secondary refrigerant loop through a first heat exchanger; the refrigerant in the first pipeline is expanded and depressurized through the throttling mechanism. According to the refrigerating system, the sorting test equipment and the refrigerating method, the actual temperature of the refrigerant is equal to the target temperature, so that the temperature of the electronic components is ensured to be in a preset temperature range, and the temperature control requirement of the electronic components is met.

Description

Refrigerating system and sorting test equipment

Technical Field

The utility model relates to the technical field of temperature control, in particular to a refrigerating system and sorting test equipment.

Background

With the continuous development of integrated circuits, the application fields of the integrated circuits are also increasing. Some special fields, such as automotive electronics, avionics, military electronics, etc., have raised requirements for reliability and stability of electronic components at various ambient temperatures. When high and low temperature testing is performed on electronic components, the capability requirements of high and low temperature testing environments built by testing equipment are higher and higher. The high temperature test environment is provided by the heater module, and the medium and low temperature test environment is provided by the refrigeration system of the test equipment.

Among various refrigeration systems, a two-stage compression cascade refrigeration system is common, and the two-stage compression cascade refrigeration system comprises a high-temperature-stage refrigeration module and a low-temperature-stage refrigeration module, and medium-temperature or low-temperature refrigerants are provided by the low-temperature-stage refrigeration module. The refrigerant provided by the low-temperature-level refrigeration module exchanges heat with the electronic components, so that the electronic components are kept in a target medium-temperature or low-temperature state.

The low-temperature-stage refrigeration module generally adopts an electronic expansion valve as a throttling device to regulate the flow of the refrigerant, so that the actual temperature of the refrigerant provided by the low-temperature-stage refrigeration module reaches the target temperature. However, in the conventional technology, it is often difficult to make the actual temperature of the refrigerant reach the target temperature, so it is difficult to ensure that the electronic component is within the preset temperature range.

Disclosure of Invention

Based on this, it is necessary to provide a refrigeration system and a sorting test device capable of enabling the actual temperature of the refrigerant to reach the target temperature so as to ensure that the temperature of the electronic component is within the preset temperature range, aiming at the problem that the actual temperature of the refrigerant is difficult to reach the target temperature in the conventional technology, thereby ensuring that the electronic component is within the preset temperature range.

A refrigeration system, comprising:

the first refrigeration module comprises a first compressor, a first condenser, the first expansion valve and a first evaporator which are sequentially communicated to form a first closed loop;

a coolant loop thermally coupled to the first closed loop through the first condenser;

the first heat exchanger and the first pipeline are characterized in that one end of the first pipeline is communicated with the exhaust end of the first compressor, and the other end of the first pipeline is communicated with the input end of the first evaporator; the first conduit is thermally coupled to the coolant loop through the first heat exchanger; and the refrigerant in the first pipeline is expanded and depressurized through the throttling mechanism.

In one embodiment, the throttling mechanism further comprises a second expansion valve, the other end of the first pipeline is communicated with the first closed loop of the part between the first expansion valve and the input end of the first evaporator, the second expansion valve is arranged on the first pipeline, and the refrigerant in the first pipeline is expanded and depressurized through the second expansion valve.

In one embodiment, the first pipeline includes a first section pipeline and a second section pipeline that are respectively located at two ends of the first heat exchanger, the first section pipeline is communicated between the first heat exchanger and an exhaust end of the first compressor, one end of the second section pipeline is communicated with the first heat exchanger, the other end of the second section pipeline is communicated with an input end of the first evaporator, and the second expansion valve is arranged on the first section pipeline.

In one embodiment, the other end of the first pipeline is communicated with the first closed loop of the part between the first condenser and the first expansion valve, and the refrigerant in the first pipeline is expanded and depressurized through the first expansion valve.

In one embodiment, the coolant circuit includes a primary circuit and a first leg in communication with each other, the primary circuit being thermally coupled to the first closed circuit by the first condenser, the first circuit being thermally coupled to the first leg by the first heat exchanger.

In one embodiment, the refrigeration system further comprises a first flow regulating valve disposed on the first branch.

In one embodiment, the refrigeration system further comprises:

the second refrigeration module comprises a second compressor, a second condenser, a third expansion valve and the first condenser which are sequentially communicated to form a second closed loop; the coolant loop is thermally coupled to the second closed loop through the second condenser to indirectly exchange heat with the first closed loop; and

the second pipeline is communicated between the output end of the third expansion valve and the suction end of the second compressor, and the second pipeline is thermally coupled with the secondary refrigerant loop through the second heat exchanger.

In one embodiment, the second conduit communicates between the first condenser and a suction end of the second compressor; or the second pipeline is communicated between the third expansion valve and the first condenser.

In one embodiment, the coolant circuit includes a primary circuit and a secondary circuit in communication with each other, the primary circuit being thermally coupled to the second closed circuit through the second condenser to indirectly exchange heat with the first closed circuit; the second conduit is thermally coupled to the second leg through the second heat exchanger.

In one embodiment, the refrigeration system further comprises a second flow regulating valve disposed on the second branch.

A sort test apparatus comprising a refrigeration system according to any of the preceding claims.

A refrigeration method employing a refrigeration system as described above, comprising the steps of:

when the actual temperature of the refrigerant flowing to the input end of the first evaporator is different from the target temperature, the throttling mechanism is controlled to adjust the actual temperature to be equal to the target temperature.

In one embodiment, the method comprises the steps of:

when the actual temperature is greater than the target temperature and the first expansion valve is at a minimum opening;

opening a second expansion valve and keeping the second expansion valve at a first preset opening, and opening a first flow regulating valve to increase the opening of the first flow regulating valve at a first preset speed until the actual temperature is equal to the target temperature;

the throttling mechanism comprises a second expansion valve, the other end of the first pipeline is communicated between the first expansion valve and the input end of the first evaporator, and the second expansion valve is arranged on the first pipeline; the secondary refrigerant loop comprises a main loop and a first branch, the main loop is thermally coupled with the first closed loop through the first condenser, the first pipeline is thermally coupled with the first branch through the first heat exchanger, and the first flow regulating valve is arranged on the first branch.

In one embodiment, the method further comprises the steps of:

when the actual temperature is less than the target temperature and the first expansion valve is at a maximum opening;

and controlling the first flow regulating valve to be closed, opening the second expansion valve and increasing the opening degree of the second expansion valve at a second preset speed until the actual temperature is equal to the target temperature.

In one embodiment, the method further comprises the steps of:

when the suction superheat degree of the second compressor is smaller than a first preset threshold value;

opening a second flow regulating valve and increasing the opening of the second flow regulating valve at a third preset speed until the suction superheat degree is greater than or equal to a second preset threshold value; the second preset threshold value is larger than or equal to the first preset threshold value;

the refrigeration system further comprises a second refrigeration module, wherein the second refrigeration module comprises a second compressor, a second condenser, a third expansion valve and the first condenser which are sequentially communicated to form a second closed loop; the secondary refrigerant circuit comprises a main circuit and a second branch circuit, wherein the main circuit is thermally coupled with the second closed circuit through the second condenser so as to indirectly exchange heat with the first closed circuit; the refrigeration system further comprises a second heat exchanger, a second pipeline serving as a part of the second closed loop and a second flow regulating valve, wherein the second pipeline is communicated between the third expansion valve and the suction end of the second compressor, the second pipeline and the second branch are thermally coupled through the second heat exchanger, and the second flow regulating valve is arranged on the second branch.

According to the refrigerating system, the refrigerating method and the sorting test equipment, when the actual temperature of the refrigerant flowing to the input end of the first evaporator is different from the target temperature, the throttling mechanism is controlled to adjust the actual temperature of the refrigerant flowing to the input end of the first evaporator so that the actual temperature of the refrigerant is equal to the target temperature, and therefore the temperature of the electronic component is ensured to be in a preset temperature range, and the temperature control requirement of the electronic component is met.

Drawings

FIG. 1 is a schematic diagram of a refrigeration system according to an embodiment of the present application;

fig. 2 is a schematic diagram of a refrigeration system according to another embodiment of the present application;

fig. 3 is a schematic diagram of a refrigeration system according to another embodiment of the present application;

FIG. 4 is a flow chart of a refrigeration method according to an embodiment of the present application;

FIG. 5 is a flow chart of a refrigeration method according to another embodiment of the present application;

FIG. 6 is a flow chart of a refrigeration method according to yet another embodiment of the present application;

fig. 7 is a flow chart of a refrigeration method according to still another embodiment of the present application.

Reference numerals illustrate:

100. a refrigeration system; 10. a first refrigeration module; 11. a first compressor; 12. a first condenser; 13. a first expansion valve; 14. a first evaporator; 15. a first temperature sensor; 20. a coolant circuit; 21. a main loop; 211. a cooling mechanism; 22. a first branch; 221. a first segment of branches; 222. a second leg; 23. a second branch; 231. a third leg; 232. a fourth leg; 30. a first heat exchanger; 40. a first pipeline; 41. a first section of tubing; 42. a second section of tubing; 50. a second refrigeration module; 51. a second compressor; 52. a second condenser; 53. a third expansion valve; 54. a second temperature sensor; 55. a pressure sensor; 60. a second expansion valve; 70. a first flow regulating valve; 80. a second heat exchanger; 90. a second pipeline; 110. a second flow regulating valve; 120. a mixing tube.

Detailed Description

In order that the above objects, features and advantages of the utility model will be readily understood, a more particular description of the utility model will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present utility model. The present utility model may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the utility model, whereby the utility model is not limited to the specific embodiments disclosed below.

In the description of the present utility model, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present utility model and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present utility model.

Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present utility model, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

In the present utility model, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

As described in the background: in the conventional technology, there are often cases where the actual temperature of the refrigerant cannot be made to reach the target temperature.

The applicant has found that the root cause of the above problems is: in the conventional technology, the low-temperature-level refrigeration module generally adopts an electronic expansion valve as a throttling device to regulate the flow of the refrigerant, so that the actual temperature of the refrigerant reaches the target temperature. However, the electronic expansion valve further reduces the low-temperature liquid refrigerant coming out of the condenser through the throttling and depressurization principle, that is, the electronic expansion valve only reduces the temperature of the refrigerant flowing through the electronic expansion valve, the temperature of the refrigerant cannot be increased, and when the low-temperature-level refrigeration module needs to obtain a higher temperature, the actual temperature of the refrigerant cannot reach the target temperature.

In order to solve the above-mentioned problems, referring to fig. 1, an embodiment of the present application provides a refrigeration system 100 for controlling the temperature of electronic components so that the temperature of the electronic components is within a preset temperature range. In one embodiment, the electronic component is a chip. Of course, in other embodiments, the type of the electronic component is not limited.

The refrigeration system 100 provided by the present application will be described in detail by taking an electronic component as an example, but the description is merely exemplary and does not limit the scope of the present application.

The refrigeration system 100 includes a first refrigeration module 10 and a throttling mechanism including a first expansion valve 13. The first refrigeration module 10 includes a first compressor 11, a first condenser 12, the first expansion valve 13, and a first evaporator 14, which are sequentially connected to form a first closed circuit. Wherein the first evaporator 14 is used for heat exchange with the chip to control the temperature of the chip. Specifically, the first expansion valve 13 is an electronic expansion valve.

When the first refrigeration module 10 is in operation, the first compressor 11 sucks the high-temperature low-pressure refrigerant gas output by the output end of the first evaporator 14, compresses the refrigerant into high-temperature high-pressure refrigerant gas through compression work, and discharges the high-temperature high-pressure refrigerant gas to the first condenser 12 from the exhaust end of the first compressor 11. When passing through the first condenser 12, the refrigerant is condensed into medium-temperature high-pressure refrigerant liquid by the first condenser 12, and is expanded and reduced in pressure into low-temperature low-pressure refrigerant liquid by the first expansion valve 13, and finally enters 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, the low-temperature low-pressure liquid refrigerant can exchange heat with the chip, so that the temperature of the chip is controlled. The refrigerant after heat exchange enters the first compressor 11 again from the output end of the first evaporator 14, and thus, the refrigerant is circulated and reciprocated.

The refrigeration system 100 also includes a coolant loop 20, the coolant loop 20 being thermally coupled to the first closed loop through the first condenser 12.

It should be noted that, the fact that the coolant circuit 20 is thermally coupled to the first closed circuit via the first condenser 12 means that: the coolant loop 20 is connected to the first closed loop through the first condenser 12 for heat exchange, i.e., the coolant loop 20 can be used for heat rejection by the first condenser 12.

In some embodiments, the coolant flowing in the coolant loop 20 is cooling water. In other embodiments, the type of coolant flowing in the coolant circuit 20 is not limited.

Specifically, the coolant circuit 20 is capable of providing coolant at a constant temperature and flow rate. If the coolant flowing in the coolant circuit 20 is cooling water, the coolant circuit 20 includes a cooling mechanism 211, the cooling mechanism 211 is a chiller, and the chiller can provide cooling water with a constant temperature and flow rate to the coolant circuit 20 for heat dissipation by the first condenser 12.

The refrigeration system 100 further includes a first heat exchanger 30 in communication with the first conduit 40, one end of the first conduit 40 being in communication with the discharge end of the first compressor 11, and the other end of the first conduit 40 being in communication with the input end of the first evaporator 14. The first line 40 is thermally coupled to the coolant circuit 20 via the first heat exchanger 30, and the coolant in the first line 40 is expanded and depressurized via a throttle mechanism. Wherein the communication of the other end of the first pipe 40 with the input of the first evaporator 14 means: any point on the first closed loop at the portion between the output of the first condenser 12 and the input of the first evaporator 14 communicates with the other end of the first line 40.

It should be noted that, the first pipe 40 is thermally coupled to the coolant circuit 20 through the first heat exchanger 30 means that: the first circuit 40 is connected to the coolant circuit 20 through the first heat exchanger 30 for heat exchange. In some embodiments, the refrigerant in the first line 40 can be expanded and depressurized by the first expansion valve 13 in the throttle mechanism. In other embodiments, the refrigerant in the first pipeline 40 can be expanded and depressurized through other structures in the throttling mechanism.

In the refrigeration system 100 provided by the application, one end of the first pipeline 40 is communicated with the exhaust end of the first compressor 11, the other end of the first pipeline 40 is communicated with the input end of the first evaporator 14, the first pipeline 40 is thermally coupled with the refrigerating medium loop 20 through the first heat exchanger 30, and the refrigerant in the first pipeline 40 is expanded and depressurized through the throttling mechanism. Thus, when the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 is less than the target temperature, the high-temperature refrigerant is controlled to flow to the first pipeline 40, and the refrigerant in the first pipeline 40 is mixed with the refrigerant in the first closed loop to increase the actual temperature of the refrigerant; when the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 is greater than the target temperature, the refrigerant in the first pipeline 40 is controlled to be mixed with the refrigerant in the first closed loop after heat exchange and temperature reduction with the refrigerant in the refrigerant loop 20 in the first heat exchanger 30 so as to reduce the actual temperature of the refrigerant, so that the actual temperature of the refrigerant is always at the target temperature, the temperature control precision is ensured, the temperature of the chip is in a preset temperature range, and the temperature control requirement of the chip is met.

It should be noted that, the actual temperatures mentioned herein are temperatures of the refrigerant flowing to the input end of the first evaporator 14, and the liquid refrigerant is the refrigerant flowing to the input end of the first evaporator 14.

The first refrigeration module 10 further includes a first temperature sensor 15, where the first temperature sensor 15 is disposed on a pipeline of the first closed loop between the first expansion valve 13 and the first evaporator 14, so as to detect an actual temperature of the liquid refrigerant.

In some embodiments, the refrigeration system 100 is a two-stage compression cascade refrigeration system. Specifically, the refrigeration system 100 further includes a second refrigeration module 50, where the second refrigeration module 50 includes a second compressor 51, a second condenser 52, a third expansion valve 53, and the first condenser 12 that are sequentially connected to form a second closed loop, and in this case, the first condenser 12 serves as a condenser of the first refrigeration module 10 and serves as an evaporator of the second refrigeration module 50. That is, the first condenser 12 is an evaporation condenser, the first refrigeration module 10 is a low-temperature-stage refrigeration module, and the second refrigeration module 50 is a high-temperature-stage refrigeration module. The coolant loop 20 is thermally coupled to the second closed loop through a second condenser 52 to indirectly exchange heat with the first closed loop. Specifically, the third expansion valve 53 is a thermal expansion valve.

It should be noted that the fact that the coolant circuit 20 is thermally coupled to the second closed circuit via the second condenser 52 means that: the coolant circuit 20 is connected to the second closed circuit via a second condenser 52 and exchanges heat. At this time, the coolant loop 20 dissipates heat directly to the second condenser 52 and indirectly to the first condenser 12 through the second closed loop.

When the second refrigeration module 50 is in operation, the second compressor 51 sucks the high-temperature low-pressure refrigerant gas output from the output end of the first condenser 12, compresses the refrigerant into high-temperature high-pressure refrigerant gas through compression work, and discharges the refrigerant gas to the second condenser 52 from the exhaust end of the second compressor 51. When passing through the second condenser 52, the refrigerant is condensed into medium-temperature high-pressure refrigerant liquid by the second condenser 52, and is expanded and reduced in pressure into low-temperature low-pressure refrigerant liquid by the third expansion valve 53, and finally enters the first condenser 12 again from the input end of the first condenser 12. When the low-temperature low-pressure liquid refrigerant enters the first condenser 12, heat exchange can be performed with the first refrigeration module 10. The refrigerant after heat exchange enters the second compressor 51 again from the output end of the first condenser 12, and thus circulates and reciprocates.

In other embodiments, the second refrigeration module 50 may be omitted, where the refrigeration system 100 is a primary refrigeration system. Of course, in other embodiments, the refrigeration system 100 may also include other refrigeration modules to form a three or more stage refrigeration system, without limitation.

In some embodiments, referring to fig. 2, the other end of the first pipeline 40 is connected to the first closed loop of the portion between the first condenser 12 and the first expansion valve 13, and the refrigerant in the first pipeline 40 is expanded and depressurized through the first expansion valve 13. The expansion and depressurization of the refrigerant in the first pipeline 40 and the expansion and depressurization of the refrigerant in the first closed loop are realized through the first expansion valve 13, so that the expansion and depressurization of the refrigerant can be realized without arranging an expansion valve on the first pipeline 40, and the structure of the refrigerating system 100 is simpler.

Specifically, when the expansion valve is not provided on the first pipe 40, a flow rate adjusting valve may be provided to adjust the flow rate of the refrigerant flowing therethrough. Of course, in other embodiments, no valve may be provided on the first conduit 40.

In other embodiments, with continued reference to fig. 1, the throttle mechanism further includes a second expansion valve 60, the other end of the first pipeline 40 is connected to the first closed loop of the portion between the first expansion valve 13 and the input end of the first evaporator 14, the second expansion valve 60 is disposed on the first pipeline 40, and the refrigerant in the first pipeline 40 is expanded and depressurized through the second expansion valve 60. At this time, the refrigerant in the first line 40 is expanded and reduced in pressure by the second expansion valve 60, and then mixed with the refrigerant in the first closed circuit reduced in pressure by the first expansion valve 13. Specifically, the second expansion valve 60 is an electronic expansion valve.

In the above arrangement, the gaseous refrigerant flowing into the first pipe 40 from the discharge end of the first compressor 11 is condensed by the refrigerant circuit 20 and is expanded and depressurized by the second expansion valve 60 to sufficiently form a liquid refrigerant, and the liquid refrigerant is mixed with the liquid refrigerant expanded and depressurized by the first expansion valve 13, so that the fluctuation of the actual temperature of the liquid refrigerant is reduced compared with the case that the first pipe 40 and the refrigerant in the first closed circuit are both expanded and depressurized by the first expansion valve 13 (if the first pipe 40 and the refrigerant in the first closed circuit are both expanded and depressurized by the first expansion valve 13, the refrigerant is likely to have a gas-liquid mixed state before the first expansion valve 13, and the refrigerant is expanded and depressurized by the first expansion valve 13 to cause uneven throttling, and further the temperature of the refrigerant exiting from the first expansion valve 13 is fluctuated).

In some embodiments, the refrigeration system 100 is provided with a mixing pipe 120, and the mixing pipe 120 is used for mixing the refrigerant in the first pipeline 40 with the refrigerant in the first closed loop. The mixing tube 120 is arranged to ensure that the two paths of refrigerant are fully mixed in the mixing tube 120 so as to avoid the temperature fluctuation of the refrigerant flowing to the input end of the first evaporator 14.

Further, the first pipeline 40 includes a first section of pipeline 41 and a second section of pipeline 42 respectively located at two ends of the first heat exchanger 30. The first section of pipeline 41 is communicated between the first heat exchanger 30 and the exhaust end of the first compressor 11, one end of the second section of pipeline 42 is communicated with the first heat exchanger 30, the other end is communicated with the input end of the first evaporator 14, and specifically, the other end of the second section of pipeline 42 is communicated with the input end of the first evaporator 14 through the mixing pipe 120. Wherein the second expansion valve 60 is disposed on the first section of pipeline 41.

When the flow rate of the coolant flowing into the first heat exchanger 30 is unchanged, the second expansion valve 60 is provided in the first-stage pipe 41, and the refrigerant in the first pipe 40 is expanded and reduced in pressure by the second expansion valve 60, so that the pressure of the refrigerant is reduced (equivalently, the mass of the refrigerant per unit volume is reduced). The refrigerant enters the first heat exchanger 30 after the pressure of the refrigerant is reduced, so that the refrigerant is more easily condensed by the refrigerant, and the liquid state ratio of the refrigerant passing through the first heat exchanger 30 is higher. In this way, if the flow rate of the refrigerant flowing through the first pipe 40 to the mixing pipe 120 is constant, the refrigerant is cooled more sufficiently by providing the second expansion valve 60 in the first-stage pipe 41 than by providing the second-stage pipe 42.

Here, when the refrigerant is in a liquid state when it flows out from the first heat exchanger 30, the refrigerant is more easily condensed means that: after the refrigerant exchanges heat through the first heat exchanger 30, the supercooling degree (the difference between the current temperature and the saturated liquid temperature) is larger, and the enthalpy difference is smaller. If the refrigerant flows out of the first heat exchanger 30 in a gas-liquid mixture state, the refrigerant is more easily condensed: the proportion of the liquid refrigerant becomes higher, the temperature is unchanged, but the enthalpy difference is smaller.

In some embodiments, the first heat exchanger 30 is a coaxial heat exchanger. Specifically, the first heat exchanger 30 includes coaxially disposed first inner and outer tubes, one of which communicates with the first conduit 40 and the other of which communicates with the coolant circuit 20. In one embodiment, a first inner tube communicates with the coolant circuit 20 and a first outer tube communicates with the first conduit 40. Of course, in other embodiments, other types of heat exchangers can be selected for the first heat exchanger 30, as long as the effect of thermally coupling the first circuit 40 to the coolant circuit 20 can be achieved.

The coolant circuit 20 includes a primary circuit 21 and a first leg 22 in communication with each other, the primary circuit 21 being thermally coupled to the second closed circuit via a second condenser 52, and the first circuit 40 being thermally coupled to the first leg 22 via a first heat exchanger 30. Specifically, the first conduit 40 is connected to the first outer tube of the first heat exchanger 30 and the first branch 22 is connected to the first inner tube of the first heat exchanger 30.

Generally, the primary circuit 21 has thicker lines and a larger flow rate, while the primary circuit 22 has thinner lines, and the thinner primary circuit 22 facilitates controlling the flow rate of the coolant flowing from the primary circuit 22 to the primary heat exchanger 30, thereby enabling high-precision control of the flow rate of the coolant flowing to the primary heat exchanger 30.

Further, the refrigeration system 100 also includes a first flow regulating valve 70, the first flow regulating valve 70 being disposed on the first branch 22 for controlling the flow of coolant to the first heat exchanger 30. Specifically, the first flow rate adjustment valve 70 may be a valve having only a flow rate adjustment function, or an expansion valve may be used as long as the flow rate adjustment function can be achieved, and is not limited thereto.

In some embodiments, the first branch 22 includes a first segment branch 221 and a second segment branch 222 at two ends of the first heat exchanger 30, the first segment branch 221 is connected to the output end of the main circuit 21, the second segment branch 222 is connected to the input end of the main circuit 21, and the first flow regulating valve 70 is disposed on the first segment branch 221. Of course, in other embodiments, the first flow control valve 70 may be provided on the second leg 222. The first flow rate adjusting valve 70 may be selectively provided to the first stage branch 221 or the second stage branch 222, and may be selected as needed, and is not limited thereto.

In some embodiments, the refrigeration system 100 further includes a second heat exchanger 80 and a second circuit 90 that is part of the second closed loop, the second circuit 90 being in communication between the output of the third expansion valve 53 and the suction of the second compressor 51, the second circuit 90 being thermally coupled to the coolant circuit 20 through the second heat exchanger 80.

It should be noted that, the second pipe 90 is thermally coupled to the coolant circuit 20 through the second heat exchanger 80 means that: the second conduit 90 is connected to the coolant circuit 20 through the second heat exchanger 80 for heat exchange.

In the above arrangement, the second pipeline 90 is connected between the output end of the third expansion valve 53 and the suction end of the second compressor 51, and the second pipeline 90 is thermally coupled with the refrigerant circuit 20 through the second heat exchanger 80, so that when the superheat degree of the suction end of the second compressor 51 is insufficient, the temperature of the refrigerant in the second pipeline 90 is increased after heat exchange with the refrigerant in the refrigerant circuit 20 through the second heat exchanger 80, so as to improve the suction superheat degree of the second compressor 51, enable the low-temperature liquid refrigerant to be sucked and gasified before entering the second compressor 51, avoid the liquid impact fault of the second compressor 51, improve the operation stability of the second refrigeration module 50, and further ensure the temperature control precision of the refrigeration system 100.

The coolant circuit 20 further includes a second leg 23, and the second conduit 90 is thermally coupled to the second leg 23 by a second heat exchanger 80. The second branch 23 has an inner diameter smaller than that of the main circuit 21, and the use of the second branch 23 having a smaller inner diameter facilitates control of the flow direction of the coolant flowing from the second branch 23 to the second heat exchanger 80, thereby enabling precise control of the flow rate of the coolant flowing to the second heat exchanger 80.

The refrigeration system 100 further includes a second flow regulating valve 110, the second flow regulating valve 110 being disposed in the second leg 23 for controlling the flow of coolant to the second heat exchanger 80. Specifically, the second flow rate adjustment valve 110 may be a valve having only a flow rate adjustment function, or may be an expansion valve, as long as the flow rate adjustment function can be achieved, and is not limited thereto.

The second heat exchanger 80 is also a coaxial heat exchanger. Specifically, the second heat exchanger 80 includes a second inner tube and a second outer tube coaxially disposed, one of the second inner tube and the second outer tube being in communication with the second conduit 90, and the other being in communication with the second branch 23. In one embodiment, a second inner tube communicates with the second branch 23 and a second outer tube communicates with the second conduit 90. Of course, in other embodiments, other types of heat exchangers can be selected for the second heat exchanger 80, as long as the effect of thermally coupling the second circuit 90 to the coolant circuit 20 can be achieved.

The second branch 23 includes a third section branch 231 and a fourth section branch 232 at two ends of the second heat exchanger 80, the third section branch 231 is communicated with an output end of the main circuit 21, the fourth section branch 232 is communicated with an input end of the main circuit 21, and the second flow regulating valve 110 is arranged on the third section branch 231. The second flow rate adjustment valve 110 may be selectively provided in the third stage branch 231 or the fourth stage branch 232, and may be selected as needed, and is not limited thereto.

In some embodiments, referring to fig. 3, the second pipeline 90 is connected between the third expansion valve 53 and the first condenser 12, and the refrigerant exchanges heat with the coolant loop 20 before entering the first condenser 12, and then enters the suction end of the second compressor 51 through the first condenser 12. In other embodiments, with continued reference to fig. 2, a second conduit 90 may be provided that is in communication between the first condenser 12 and the suction side of the second compressor 51, wherein the coolant enters the suction side of the second compressor 51 directly after exchanging heat with the coolant loop 20.

It should be noted that, when the second pipeline 90 is connected to the suction ends of the first condenser 12 and the second compressor 51, the phase of the suction refrigerant of the second compressor 51 of the second refrigeration module 50 can be directly adjusted by the second flow rate adjusting valve 110, so as to conveniently control the suction of the second compressor 51 to have no liquid state. When the second line 90 is connected between the third expansion valve 53 and the first condenser 12, the suction of the second compressor 51 is commonly regulated by the third expansion valve 53 and the second flow rate regulating valve 110.

Further, the second refrigeration module 50 further includes a second temperature sensor 54 and a pressure sensor 55, the pressure sensor 55 is used for detecting the suction pressure of the second compressor 51, and the second temperature sensor 54 is used for detecting the suction temperature of the second compressor 51.

In another embodiment of the present application, a sorting test device including the above-mentioned refrigeration system 100 is further provided, and since the refrigeration system 100 has the beneficial effects, the sorting test device has the same beneficial effects, and will not be described in detail herein.

Referring to fig. 4, a further embodiment of the present application further provides a refrigeration method of the refrigeration system 100, including the steps of:

s100: when the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 is not equal to the target temperature, the throttle mechanism is controlled to adjust the actual temperature to be equal to the target temperature.

Here, the actual temperature is the real-time temperature of the refrigerant flowing to the input end of the first evaporator 14, and can be measured by the first temperature sensor 15 of the first refrigeration module 10. The target temperature is a temperature manually set and can be set according to the temperature control requirement of the chip. If the chip needs to be controlled at a lower temperature, the target temperature is lower, and if the chip needs to be controlled at a higher temperature, the target temperature is higher.

In the above refrigeration method, when the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 is different from the target temperature, the throttle mechanism is controlled to adjust the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 so that the actual temperature of the refrigerant is equal to the target temperature, thereby ensuring that the temperature of the chip is within the preset temperature range and meeting the temperature control requirement of the chip.

Further, referring to fig. 5, the refrigeration method further includes the steps of:

s200: when the actual temperature is greater than the target temperature, and the first expansion valve 13 is at the minimum opening;

the first expansion valve 13 can be adjusted between a maximum opening degree and a minimum opening degree in the working process, and the maximum opening degree and the minimum opening degree of the first expansion valve 13 need to be determined during sample debugging. In general, the opening degree of the first expansion valve 13 when fully opened is set to 100%, the opening degree of the first expansion valve 13 when closed is set to 0, and the maximum opening degree and the minimum opening degree of the first expansion valve are values between 0 and 100%.

S300: the second expansion valve 60 is opened and maintained at a first preset opening, and the first flow rate adjustment valve 70 is opened to increase the opening of the first flow rate adjustment valve 70 at a first preset speed until the actual temperature is equal to the target temperature.

The throttle mechanism comprises a second expansion valve 60, the other end of the first pipeline 40 is communicated between the first expansion valve 13 and the input end of the first evaporator 14, and the second expansion valve 60 is arranged on the first pipeline 40; the coolant circuit 20 includes a main circuit 21 and a first leg 22, the main circuit 21 is thermally coupled to the first closed circuit via a first condenser 12, the first circuit 40 is thermally coupled to the first leg 22 via a first heat exchanger 30, and a first flow control valve 70 is disposed on the first leg 22.

It should be noted that, the first preset opening and the first preset speed are selected according to the actual working condition, and the setting of the first preset opening and the first preset speed can be only required to ensure that the actual temperature is equal to the target temperature. Specifically, the first preset speed is 0.1%/s. Of course, in other embodiments, the first preset speed may have other values, such as 0.2%/s, which is not limited herein.

When the first expansion valve 13 is at the minimum opening, it is proved that the actual temperature of the refrigerant flowing to the input end of the first evaporator 14 reaches the target temperature by adjusting the first expansion valve 13, and then the second expansion valve 60 is opened, and the flow rate of the refrigerant in the first branch 22 is controlled by adjusting the opening of the first flow rate adjusting valve 70, so that the temperature of the refrigerant in the first pipeline 40 is reduced by the refrigerant and is mixed with the refrigerant in the first closed loop.

Further, it is possible to set the temperature of the coolant in the coolant circuit 20 to be always maintained at 20 ℃, while the discharge temperature of the first compressor 11 in the first refrigeration module 10 is far higher than this temperature, while the circulation flow rate of the coolant in the coolant circuit 20 is constant. Therefore, by adjusting the opening of the first flow rate adjustment valve 70, the flow rate of the coolant in the second branch 23 can be adjusted, and the temperature of the coolant in the first line 40 can be adjusted, thereby adjusting the outlet temperature (actual temperature) of the coolant in the first refrigeration module 10.

Still further, before step S200, the method further comprises the steps of:

when the actual temperature is greater than the target temperature, and when the opening degree of the first expansion valve 13 is greater than the minimum opening degree, the opening degree of the first expansion valve 13 is reduced at a fourth preset speed until the actual temperature is equal to the target temperature. And when the first expansion valve 13 reaches the minimum opening degree, if the actual temperature is still greater than the target temperature, the step of S300 is performed. Specifically, the fourth preset speed is 0.1%/s.

In some embodiments, referring to fig. 6, the refrigeration method further comprises the steps of:

s400: when the actual temperature is less than the target temperature and the first expansion valve 13 is at the maximum opening;

s500: the first flow rate adjusting valve 70 is controlled to be closed, the second expansion valve 60 is opened, and the opening degree of the second expansion valve 60 is increased at a second preset speed until the actual temperature is equal to the target temperature.

Similarly, the second preset speed is set according to the actual working condition. In one embodiment, the second predetermined speed is 0.1%/s.

When the actual temperature is less than the target temperature and the first expansion valve 13 is at the maximum opening, the purpose that the actual temperature is equal to the target temperature cannot be achieved only by adjusting the first expansion valve 13 is proved, and at this time, the second expansion valve 60 is opened and the opening of the second expansion valve 60 is increased at the second preset speed, so as to control the flow rate of the high-temperature gaseous refrigerant in the first pipeline 40. The liquid refrigerant of the first refrigeration module 10 is obtained by mixing the refrigerant in the first pipeline 40 with the refrigerant in the first closed loop, and the actual temperature is also obtained by mixing the refrigerant in the first closed loop with the refrigerant in the first closed loop, so as to ensure that the actual temperature is equal to the target temperature.

Further, the refrigeration method further comprises the steps of:

when the suction superheat of the second compressor 51 is less than the first preset threshold;

the suction superheat degree is the difference between the suction temperature of the second compressor 51 and the saturated evaporating temperature thereof, and the first preset threshold can be selected according to the actual working condition, for example, in a specific embodiment, the first preset threshold is set to be 5 ℃. The suction temperature can be measured by the second temperature sensor 54 of the second refrigeration module 50.

Opening the second flow regulating valve 110 and increasing the opening of the second flow regulating valve 110 at a third preset speed until the suction superheat degree is greater than a second preset threshold, wherein the second preset threshold is greater than or equal to the first preset threshold.

The refrigeration system 100 further includes a second refrigeration module 50, where the second refrigeration module 50 includes a second compressor 51, a second condenser 52, a third expansion valve 53, and a first condenser 12 that are sequentially connected to form a second closed loop; the coolant circuit 20 includes a primary circuit 21 and a second leg 23, the primary circuit 21 being thermally coupled to the second closed circuit via a second condenser 52 for indirect heat exchange with the first closed circuit; the refrigeration system 100 further includes a second heat exchanger 80, a second pipeline 90 as part of a second closed loop, and a second flow regulating valve 110, the second pipeline 90 being connected between the third expansion valve 53 and the suction end of the second compressor 51, the second pipeline 90 being thermally coupled to the second branch 23 through the second heat exchanger 80, the second flow regulating valve 110 being disposed on the second branch 23.

Specifically, the third preset speed and the second preset threshold are selected according to the actual working conditions, and the selection of the second preset threshold can ensure that the refrigerant entering the second compressor 51 is in a gaseous state. In one embodiment, the third preset speed is 0.1%/s and the second preset threshold is 10 ℃.

When the suction superheat of the second compressor 51 is smaller than the first preset threshold, the suction refrigerant of the second compressor 51 is considered to be not completely evaporated, and is in a gas-liquid mixed state, and the second compressor 51 has a risk of damage caused by the liquid refrigerant. The flow rate of the coolant in the second leg 23 is adjusted by opening the second flow rate adjustment valve 110 and increasing the opening of the second flow rate adjustment valve 110 at a third preset rate. Because the second branch 23 of the coolant loop 20 exchanges heat with the second pipeline 90 through the second heat exchanger 80, the suction temperature of the second compressor 51 can be adjusted, so that the suction superheat degree of the second compressor 51 is greater than a second preset threshold value, and the suction refrigerant is ensured to be in a gaseous state, and the damage caused by the suction of the second compressor 51 due to liquid carrying is avoided.

The refrigeration process will be described in detail in one embodiment. Before describing the refrigeration method, some description is made of the refrigeration system 100. The refrigeration system 100 is a two-stage cascade refrigeration system, and includes a first refrigeration module 10, a second refrigeration module 50, and a throttling mechanism including a first expansion valve 13 and a second expansion valve 60. The refrigeration system 100 further includes a first line 40, a second line 90, a first heat exchanger 30, and a second heat exchanger 80, and the second expansion valve 60 is disposed on the second line 42. The coolant circuit 20 includes a main circuit 21, a first branch 22, and a second branch 23, the first branch 22 having a first flow control valve 70, and the second branch 23 having a second flow control valve 110. The main circuit 21 includes a chiller for supplying cooling water having a constant temperature and flow rate, and specifically, the temperature of the cooling water supplied from the chiller is always 20 ℃. The first temperature sensor 15 is used for detecting the actual temperature of the liquid refrigerant, the second temperature sensor 54 is used for detecting the suction temperature of the second compressor 51, and the pressure sensor 55 is used for detecting the suction pressure of the second compressor 51. Reference is made to the description above regarding the connection of the components.

Specifically, the first preset speed, the second preset speed, the third preset speed, the fourth preset speed, and the fifth preset speed mentioned below are all set to 0.1%/s.

Specifically, referring to fig. 7, the refrigeration method includes the steps of:

the water chiller is started to circulate the cooling water in the main circuit 21, and the first flow rate adjustment valve 70, the second flow rate adjustment valve 110, and the second expansion valve 60 are kept closed.

The second refrigeration module 50 is started, and the opening degree of the third expansion valve 53 is controlled and adjusted by the relationship between the saturated evaporation temperature and the target evaporation temperature, which are converted from the suction pressure of the second compressor 51 measured by the pressure sensor 55. Whether the saturated evaporating temperature of the second refrigeration module 50 reaches the target value is determined, and if the saturated evaporating temperature does not reach the target value, the opening degree of the third expansion valve 53 is adjusted so that the saturated evaporating temperature of the second refrigeration module 50 reaches the target value, and after the saturated evaporating temperature reaches the target value, the opening degree of the third expansion valve 53 is kept unchanged.

When the saturated evaporating temperature reaches the target value, it is determined whether the suction superheat degree of the second compressor 51 is smaller than a first preset threshold.

When the suction superheat degree is smaller than a first preset threshold value;

opening the second flow regulating valve 110 and increasing the opening of the second flow regulating valve 110 at a third preset speed until the suction superheat degree is greater than or equal to a second preset threshold. And when the suction superheat degree is equal to or greater than the second preset threshold value, the opening degree of the second flow regulating valve 110 is kept unchanged until the suction superheat degree is smaller than the second preset threshold value again.

After the second refrigeration module 50 is stably operated, the first refrigeration module 10 is started. The first expansion valve 13 is opened, and the second expansion valve 60 and the first flow rate adjustment valve 70 are closed.

When the actual temperature of the liquid refrigerant is equal to the target temperature, the opening degree of the first expansion valve 13 is kept unchanged.

When the actual temperature is less than the target temperature and the first expansion valve 13 is at the maximum opening;

the first flow rate adjusting valve 70 is kept closed, the second expansion valve 60 is opened, and the opening degree of the second expansion valve 60 is increased at a second preset speed until the actual temperature is equal to the target temperature.

Wherein, when the actual temperature is less than the target temperature but the first expansion valve 13 is not at the maximum opening, the opening of the first expansion valve 13 is increased at a fifth preset speed until the actual temperature is equal to the target temperature.

When the actual temperature is greater than the target temperature and the first expansion valve 13 is at the minimum opening;

the second expansion valve 60 is opened and maintained at a first preset opening, and the first flow rate adjustment valve 70 is opened to increase the opening of the first flow rate adjustment valve 70 at a first preset speed until the actual temperature is equal to the target temperature.

Wherein, when the actual temperature is greater than the target temperature but the first expansion valve 13 is not at the minimum opening, the opening of the first expansion valve 13 is reduced at the fourth preset speed until the actual temperature is equal to the target temperature or until the opening of the first expansion valve 13 is reduced to the minimum opening.

The refrigerating system 100, the sorting test equipment and the refrigerating method provided by the embodiment of the application have the following beneficial effects:

1. the coolant in the second leg 23 of the coolant circuit 20 exchanges heat with the coolant in the second circuit 90 in the second heat exchanger 80 to regulate the suction temperature of the second compressor 51. Because the temperature of the coolant provided by the coolant circuit 20 is much higher than the suction temperature of the second compressor 51, the suction temperature of the second compressor 51 is increased by heat exchange between the coolant and the suction refrigerant of the second compressor 51, thereby solving the temperature of the suction liquid carried by the second compressor 51 and avoiding damage to the second compressor 51. And because the temperature and flow of the secondary refrigerant are constant, the suction temperature of the second compressor 51 can be constant, the operation stability of the second refrigeration module 50 is ensured, and the system fluctuation degree caused by abrupt change of working conditions when the whole refrigeration system 100 operates is reduced.

2. The coolant in the first branch 22 of the coolant loop 20 exchanges heat with the coolant in the first pipeline 40 in the first heat exchanger 30, and the heat medium in the first pipeline 40 exchanges heat with the coolant and then is mixed with the coolant in the first closed loop to adjust the actual temperature of the liquid coolant. Because the temperature of the coolant provided by the coolant loop 20 is lower than the temperature of the coolant in the first pipeline 40, the temperature of the coolant in the first pipeline 40 is reduced by heat exchange between the coolant and the coolant in the first pipeline 40, so that the actual temperature of the coolant in the liquid is regulated by mixing with the coolant in the first closed loop, the actual temperature is always at the target temperature, the temperature of the chip is in the preset temperature range, and the temperature control requirement of the chip is met. Meanwhile, the temperature and flow of the secondary refrigerant are constant, the actual temperature is constant, the operation stability of the first refrigeration module 10 is guaranteed, and the system fluctuation degree caused by abrupt change of working conditions when the whole refrigeration system 100 operates is reduced.

3. The utility model designs a heat exchange mode of the secondary refrigerant loop, the low-temperature-level refrigerating module and the high-temperature-level refrigerating module, and can simultaneously improve the air return problem of the high-temperature-level compressor and the liquid outlet problem of the low-temperature-level refrigerant by utilizing the secondary refrigerant loop, thereby improving the integral operation stability and the temperature control precision of the cascade refrigerating system.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the utility model, which are described in detail and are not to be construed as limiting the scope of the utility model. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the utility model, which are all within the scope of the utility model. Accordingly, the scope of protection of the present utility model is to be determined by the appended claims.

Claims (11)

1. A refrigeration system, comprising:

The refrigerating system comprises a first refrigerating module (10) and a throttling mechanism, wherein the throttling mechanism comprises a first expansion valve (13), and the first refrigerating module (10) comprises a first compressor (11), a first condenser (12), the first expansion valve (13) and a first evaporator (14) which are sequentially communicated to form a first closed loop;

-a coolant circuit (20), said coolant circuit (20) being thermally coupled to said first closed circuit by said first condenser (12);

a first heat exchanger (30) and a first pipeline (40), wherein one end of the first pipeline (40) is communicated with the exhaust end of the first compressor (11), and the other end of the first pipeline (40) is communicated with the input end of the first evaporator (14); the first conduit (40) is thermally coupled to the coolant circuit (20) through the first heat exchanger (30); the refrigerant in the first pipeline (40) is expanded and depressurized through the throttling mechanism.

2. The refrigeration system according to claim 1, wherein the throttle mechanism further comprises a second expansion valve (60), the other end of the first pipe (40) is connected to the first closed circuit of the portion between the first expansion valve (13) and the input end of the first evaporator (14), the second expansion valve (60) is provided on the first pipe (40), and the refrigerant in the first pipe (40) is expanded and depressurized by the second expansion valve (60).

3. A refrigeration system according to claim 2, wherein the first pipe (40) comprises a first pipe section (41) and a second pipe section (42) which are respectively positioned at two ends of the first heat exchanger (30), the first pipe section (41) is communicated between the first heat exchanger (30) and the exhaust end of the first compressor (11), one end of the second pipe section (42) is communicated with the first heat exchanger (30), the other end is communicated with the input end of the first evaporator (14), and the second expansion valve (60) is arranged on the first pipe section (41).

4. A refrigeration system according to claim 1, wherein the other end of the first line (40) is connected to the first closed circuit of the portion between the first condenser (12) and the first expansion valve (13), and the refrigerant in the first line (40) is expanded and depressurized by the first expansion valve (13).

5. A refrigeration system according to claim 1, wherein the coolant circuit (20) comprises a main circuit (21) and a first branch (22) in communication with each other, the main circuit (21) being thermally coupled to the first closed circuit through the first condenser (12), the first circuit (40) being thermally coupled to the first branch (22) through the first heat exchanger (30).

6. The refrigeration system of claim 5, further comprising a first flow regulating valve (70), the first flow regulating valve (70) being disposed on the first branch (22).

7. The refrigeration system of any of claims 1-6, further comprising:

a second refrigeration module (50) comprising a second compressor (51), a second condenser (52), a third expansion valve (53) and the first condenser (12) which are sequentially communicated to form a second closed loop; the coolant loop (20) is thermally coupled to the second closed loop through the second condenser (52) to indirectly exchange heat with the first closed loop; and

a second heat exchanger (80) and a second conduit (90) that is part of the second closed loop, the second conduit (90) being in communication between the output of the third expansion valve (53) and the suction of the second compressor (51), the second conduit (90) being thermally coupled to the coolant loop (20) through the second heat exchanger (80).

8. The refrigeration system of claim 7, wherein the second conduit (90) communicates between the first condenser (12) and a suction end of the second compressor (51); or the second pipeline (90) is communicated between the third expansion valve (53) and the first condenser (12).

9. A refrigeration system according to claim 7, wherein said coolant circuit (20) comprises a main circuit (21) and a second branch (23) in communication with each other, said main circuit (21) being thermally coupled to said second closed circuit by said second condenser (52) for indirect heat exchange with said first closed circuit; the second line (90) is thermally coupled to the second branch (23) via the second heat exchanger (80).

10. The refrigeration system of claim 9, further comprising a second flow regulating valve (110), the second flow regulating valve (110) being provided on the second branch (23).

11. A sorting test apparatus comprising a refrigeration system according to any one of claims 1 to 10.