Ultralow-temperature refrigerating unit system

Abstract

The utility model discloses an ultra-low temperature refrigerating unit system which is composed of a cold source, a refrigerating unit and a refrigerating machine inner machine which are sequentially connected through a connecting pipe, and a buffer water tank, a water pump and a water fluorine heat exchanger which are connected through a connecting pipe are arranged in the refrigerating unit to form a chilled water loop. A steam separator, a compressor, an oil separator, a storage tank, a liquid storage device, a fluorine-fluorine heat exchanger and a first electronic expansion valve which are connected through connecting pipes form a main flow refrigerant loop, and a connecting pipe provided with a second electronic expansion valve and arranged on the connecting pipe of the first electronic expansion valve and the fluorine-fluorine heat exchanger serves as a branch flow refrigerant loop. A first electromagnetic valve is arranged on a connecting pipe of the first electronic expansion valve and the refrigerator indoor unit, and a second electronic expansion valve is arranged on the branch refrigerant loop. The ultra-low temperature refrigeration device can provide an ultra-low temperature refrigeration effect and can conveniently and rapidly recover the refrigerant.

Description

Technical Field

[0001] The utility model relates to the technical field of refrigeration technology and refrigeration equipment, and in particular to an ultra-low temperature refrigeration unit system. Background Art

[0002] A refrigeration unit is a commonly used industrial refrigeration equipment that can cool air or water to the required temperature by compressing, condensing, expanding, evaporating and other processes of the refrigerant in the compressor, thereby lowering the temperature of the air or water.

[0003] With the advancement of science and technology, especially the increasing demand for ultra-low temperature environments, traditional refrigeration units can no longer fully meet the requirements of certain special application scenarios. For example, in the fields of biomedical research, food processing, and specific material processing, it is necessary to achieve lower temperatures while ensuring system stability and efficiency.

[0004] At present, most ultra-low temperature refrigeration units on the market use single-stage or multi-stage compressor refrigeration methods to achieve low temperature goals. In this mode, an electric motor is first used to drive the compressor to suck in and compress the low-pressure gaseous refrigerant into a high-temperature and high-pressure state; then it enters the condenser to release heat and become liquid; then it passes through a throttling device (such as an expansion valve) to reduce the pressure and temperature and become a low-temperature, low-pressure liquid; finally, it enters the evaporator to absorb external heat and be converted into gas again to complete a cycle; in addition, in order to further reduce the temperature, a cascade refrigeration system is sometimes used, that is, two independent but interrelated refrigeration circuits are used in combination, one of which is responsible for providing initial cooling, and the other continues to cool on this basis to achieve a lower temperature level.

[0005] Although the above method can meet the ultra-low temperature requirements to a certain extent, there are still some problems in the actual application process: first, the energy consumption is high. Since reaching extremely low temperatures often requires a larger power compressor and a longer working time, this directly leads to higher energy consumption; second, refrigerant recovery is difficult and pressure management is complicated. When the system stops running, the refrigerant remaining in the pipeline will generate a higher pressure due to the increase in temperature, which not only increases safety risks but may also cause environmental pollution.

[0006] Especially when using R23 refrigerant, due to its higher pressure at room temperature, pressure management after shutdown becomes more complicated. At this time, the traditional treatment method is to close all valves immediately after the system is shut down, but this will cause the refrigerant to accumulate in the pipeline and generate high pressure, increasing the risk of leakage.

[0007] To this end, the present application proposes an ultra-low temperature refrigeration unit system to solve the above technical problems. Utility Model Content

[0008] The main purpose of the utility model is to provide an ultra-low temperature refrigeration unit system that can provide ultra-low temperature refrigeration effect and can conveniently and quickly recover refrigerant.

[0009] In order to solve the above technical problems, the utility model provides an ultra-low temperature refrigeration unit system, which consists of a cold source, a refrigeration unit and a refrigeration unit connected in sequence by connecting pipes, and the cold source is provided with a cold water inlet and a cold water outlet, and the cold water inlet and the cold water outlet are both connected to the refrigeration unit through connecting pipes, wherein: the interior of the refrigeration unit is composed of a mainstream refrigerant circuit, a branch refrigerant circuit and a chilled water circuit, and the mainstream refrigerant circuit, the branch refrigerant circuit and the chilled water circuit cooperate with each other to quickly recover the refrigerant in the system.

[0010] Furthermore, the refrigeration unit is internally provided with a buffer water tank, a water pump and a water-fluorine heat exchanger which are connected in sequence through connecting pipes. The buffer water tank is connected to the cold water inlet through a connecting pipe, and the water-fluorine heat exchanger is connected to the cold water outlet through a connecting pipe. The water-fluorine heat exchanger is used to connect to the mainstream refrigerant circuit and perform heat exchange operations. The buffer water tank, water pump, water-fluorine heat exchanger and the connecting pipes between them constitute a chilled water circuit.

[0011] Furthermore, the refrigeration unit is further provided with a vapor separator, a compressor, an oil separator, a storage tank, a liquid reservoir, a fluoro-fluoro heat exchanger and a first electronic expansion valve which are connected in sequence through connecting pipes. The connecting pipe portion of the storage tank and the liquid reservoir is connected through the water-fluorine heat exchanger and performs heat exchange operations. The first electronic expansion valve is connected to the refrigerator internal unit through a connecting pipe and is used to transport liquid refrigerant to the refrigerator internal unit. The vapor separator is connected to the refrigerator internal unit through a connecting pipe and is used to collect the vapor refrigerant in the refrigerator internal unit. The vapor separator, compressor, oil separator, storage tank, liquid reservoir, fluoro-fluoro heat exchanger and the first electronic expansion valve and the connecting pipes between them constitute a mainstream refrigerant circuit.

[0012] Furthermore, the connecting pipe between the first electronic expansion valve and the fluorofluoro heat exchanger is also connected to the compressor by providing a connecting pipe with a second electronic expansion valve. The connecting pipe between the second electronic expansion valve and the compressor is connected through the fluorofluoro heat exchanger and performs heat exchange operations. The connecting pipe with the second electronic expansion valve is set as a branch refrigerant circuit.

[0013] Furthermore, a first solenoid valve is provided on the connecting pipe between the first electronic expansion valve and the internal unit of the refrigerator, and a second solenoid valve is provided on the connecting pipe between the steam separator and the internal unit of the refrigerator.

[0014] Furthermore, a pressure sensor and a third temperature sensor are provided on the connecting pipe between the steam separator and the internal unit of the refrigeration machine.

[0015] Furthermore, a second temperature sensor is provided on the connecting pipe between the compressor and the oil separator.

[0016] Furthermore, a first temperature sensor and a fourth temperature sensor are provided on the branch refrigerant circuit, and the first temperature sensor and the fourth temperature sensor are respectively located at two ends of the fluorofluoro heat exchanger.

[0017] Furthermore, a connecting valve is provided on the connecting pipe between the refrigeration unit and the internal unit of the refrigeration machine.

[0018] The beneficial effects of the present invention are as follows:

[0019] 1. The utility model sets a mainstream refrigerant circuit, a branch refrigerant circuit and a chilled water circuit inside the refrigeration unit, and can use the heat exchanger and the compressor to refrigerate and compress in sequence to achieve an ultra-low temperature effect. Compared with the traditional multi-stage compressor refrigeration, the structure is simpler and more convenient to maintain.

[0020] 2. Since the pressure of R23 refrigerant is high at room temperature, the utility model recovers the refrigerant through the compressor, cooperates with the opening and closing of the first solenoid valve and the second solenoid valve, and quickly and stably recovers the refrigerant in the system, thereby improving the system operation efficiency and safety and extending the service life of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0022] Figure 1 This is a schematic diagram of the overall system structure of the utility model;

[0023] Figure 2 This is a schematic diagram of the internal system structure connection of the refrigeration unit of the present invention;

[0024] Figure 3 This is a schematic diagram of the refrigerant flow path in the internal system of the refrigeration unit of the present invention.

[0025] In the picture:

[0026] 1. Cold source; 101. Cold water inlet; 102. Cold water outlet;

[0027] 2. Refrigeration unit; 201. Buffer water tank; 202. Water pump; 203. Water-fluorine heat exchanger; 204. Liquid reservoir; 205. Fluorine-fluorine heat exchanger; 206. First temperature sensor; 207. Compressor; 208. Second temperature sensor; 209. Oil separator; 210. Storage tank; 211. First electronic expansion valve; 212. First solenoid valve; 213. Second solenoid valve; 214. Pressure sensor; 215. Third temperature sensor; 216. Steam separator; 217. Second electronic expansion valve; 218. Fourth temperature sensor;

[0028] 3. Refrigeration unit; 31. Connecting valve. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] In the embodiment, see Figures 1 to 3 .

[0031] like Figure 1 As shown, the utility model provides an ultra-low temperature refrigeration unit system, which is composed of a cold source 1, a refrigeration unit 2 and a refrigeration unit 3 connected in sequence by connecting pipes. A cold water inlet 101 and a cold water outlet 102 are provided in the cold source 1, and the cold water inlet 101 and the cold water outlet 102 are both connected to the refrigeration unit 2 through connecting pipes, wherein the interior of the refrigeration unit 2 is composed of a mainstream refrigerant circuit, a branch refrigerant circuit and a chilled water circuit. At this time, the mainstream refrigerant circuit, the branch refrigerant circuit and the chilled water circuit cooperate with each other to quickly recover the refrigerant in the system.

[0032] It should be noted that the ultra-low temperature refrigeration system uses R23 refrigerant for cooling, and the cooling temperature can reach minus 80 degrees.

[0033] In addition, in a specific embodiment, a connecting valve 31 is further provided on the connecting pipe between the refrigeration unit 2 and the refrigeration unit 3, which is used to control the installation and disassembly of the refrigeration unit 3 and the refrigeration unit 2, so as to facilitate the use of the refrigeration unit 2 to control the flow of refrigerant in the refrigeration unit 3, and further control the cooling regulation in the specified control environment. At the same time, it is also convenient to quickly replace the refrigeration unit 3 in the specified environment to complete the maintenance, update and replacement operations of the refrigeration unit 3.

[0034] Further, such as Figure 2 and Figure 3 As shown, in the ultra-low temperature refrigeration system, the main refrigerant circuit, the branch refrigerant circuit and the chilled water circuit specifically include:

[0035] (1) Chilled water circuit: It consists of a buffer water tank 201, a water pump 202, a water-fluorine heat exchanger 203, and connecting pipes, and is used to provide 7-degree cold water to the chiller.

[0036] Specifically, the buffer water tank 201, the water pump 202 and the water-fluorine heat exchanger 203 connected in sequence by connecting pipes are arranged inside the refrigeration unit 2, wherein the buffer water tank 201 is connected to the cold water inlet 101 through a connecting pipe, and the water-fluorine heat exchanger 203 is connected to the cold water outlet 102 through a connecting pipe. The water-fluorine heat exchanger 203 is used to connect to the mainstream refrigerant circuit and perform heat exchange operations.

[0037] At this time, the chilled water flows in the following manner: in the chilled water circuit, the chilled water starts from the cold source 1, passes through the buffer water tank 201, the water pump 202 and the water-fluorine heat exchanger 203 in sequence, and is finally recovered to the cold source 1.

[0038] Therefore, by configuring a chilled water circuit consisting of a buffer water tank 201, a water pump 202 and a water-fluorine heat exchanger 203 in the refrigeration unit 2, it is possible to stabilize the circulation of chilled water, thereby ensuring the consistent stability of the cooling performance of the cold source 1 of the entire system, and ultimately achieving an efficient and stable cooling effect.

[0039] (2) Mainstream refrigerant circuit: It consists of a steam separator 216, a compressor 207, an oil separator 209, a storage tank 210, a liquid storage tank 204, a fluoro-fluoro heat exchanger 205 and a first electronic expansion valve 211 as well as interconnected pipes. It can effectively control and adjust the state conversion process of the refrigerant, thereby ensuring a good refrigeration effect even under ultra-low temperature conditions while reducing energy consumption. Here, the fluoro-fluoro heat exchanger 205 is used in the mainstream refrigerant circuit to cool the liquid refrigerant and improve the refrigerant supercooling.

[0040] Specifically, the steam separator 216, the compressor 207, the oil separator 209, the storage tank 210, the liquid reservoir 204, the fluoro-fluoro heat exchanger 205 and the first electronic expansion valve 211, which are connected in sequence through connecting pipes, are arranged inside the refrigeration unit 2, and at this time, the connecting pipe part of the storage tank 210 and the liquid reservoir 204 is connected through the water-fluorine heat exchanger 203 and performs heat exchange operations.

[0041] It can be further explained here that the first electronic expansion valve 211 is connected to the refrigerator indoor unit 3 through a connecting pipe, and is used to transport liquid refrigerant to the refrigerator indoor unit 3, and the steam separator 216 is connected to the refrigerator indoor unit 3 through a connecting pipe, and is used to collect the vapor refrigerant of the refrigerator indoor unit 3.

[0042] In addition, it should be noted that, in a specific embodiment, a pressure sensor 214 and a third temperature sensor 215 are also provided on the connecting pipe between the steam separator 216 and the refrigeration unit 3, which are used to sense and obtain the temperature data and pressure data of the vapor refrigerant obtained when the mainstream refrigerant circuit is operating normally to transport the refrigerant.

[0043] Furthermore, it should be noted that, in a specific embodiment, a second temperature sensor 208 is further provided on the connecting pipe between the compressor 207 and the oil separator 209 for sensing and obtaining refrigerant temperature data in the refrigerant recovery state.

[0044] At this time, by selecting R23 as the refrigerant and combining it with the effective refrigerant recovery mechanism of compressor 207, it is possible to significantly reduce the risk of refrigerant leakage and the environmental pollution problems caused by it while maintaining high-efficiency refrigeration, reflecting the green and environmentally friendly design concept.

[0045] At this time, the flow mode of R23 refrigerant is:

[0046] Liquid R23 refrigerant is stored in the storage tank 210 and passes through the water-fluorine heat exchanger 203, the liquid reservoir 204, the fluorine-fluorine heat exchanger 205 and the first electronic expansion valve 211 in sequence to enter the refrigerant indoor unit to complete the refrigeration operation;

[0047] The vapor R23 refrigerant after the refrigeration operation passes through the vapor separator 216, the compressor 207, and the oil separator 209 in sequence to return to the liquid R23 refrigerant and is stored in the storage tank 210 again.

[0048] (3) Branch refrigerant circuit: It is provided with a connecting pipe with a second electronic expansion valve 217, and the branch refrigerant circuit is connected to the compressor 207, which is used to cool the exhaust temperature of the compressor 207 and increase the subcooling degree of the mainstream refrigerant circuit.

[0049] It needs to be explained that at this time the compressor 207 is provided with three groups of return air ports, including a low-pressure chamber return air port, a medium-pressure chamber return air port and a high-pressure chamber exhaust port. The medium-pressure chamber return air port in the return air port is used to connect to the branch refrigerant circuit, the high-pressure chamber exhaust port in the return air port is used to connect to the connecting pipe of the oil separator 209 in the mainstream refrigerant circuit for exhaust operation, and the low-pressure chamber return air port in the return air port is used to connect to the connecting pipe of the steam separator 216 in the mainstream refrigerant circuit.

[0050] Specifically, one end of the branch refrigerant circuit is set on the connecting pipe between the first electronic expansion valve 211 and the fluorofluoro heat exchanger 205, and the other end of the branch refrigerant circuit is connected to the compressor 207. At the same time, the connecting pipe part of the second electronic expansion valve 217 and the compressor 207 is connected through the fluorofluoro heat exchanger 205 and performs heat exchange operation.

[0051] At this time, by adding a branch refrigerant circuit with a second electronic expansion valve 217 between the first electronic expansion valve 211 and the fluorofluoro heat exchanger 205, the function of regulating the refrigerant flow in the main circuit can be achieved, thereby optimizing the energy distribution of the entire system and making the refrigeration process more energy-saving and efficient.

[0052] In addition, it should be noted that, in a specific embodiment, a first temperature sensor 206 and a fourth temperature sensor 218 are also provided on the branch refrigerant circuit, and the first temperature sensor 206 and the fourth temperature sensor 218 are respectively located at both ends of the fluorofluoro heat exchanger 205, for sensing and obtaining the temperature difference data of the refrigerant before and after the heat exchange when the branch refrigerant circuit is operating normally to transport the refrigerant, thereby facilitating the control of the switch control of the second electronic expansion valve 217, comprehensively adjusting the overall circuit system, increasing the supercooling degree of the mainstream circuit, improving the refrigeration effect, and realizing dynamic adjustment and control of the branch refrigerant circuit.

[0053] At this time, the flow mode of R23 refrigerant is: the liquid R23 refrigerant passes through the fluorofluoro heat exchanger 205 in the mainstream refrigerant circuit, is processed by the second electronic expansion valve 217, and then returns to the fluorofluoro heat exchanger 205 to complete the heat exchange operation, and finally enters the compressor 207 and passes through the compressor 207 and oil separator 209 of the mainstream refrigerant circuit again before being stored in the storage tank 210 again.

[0054] In summary, the system structure sets up a mainstream refrigerant circuit, a branch refrigerant circuit and a chilled water circuit inside the refrigeration unit 2, and can use the heat exchanger and compressor 207 to refrigerate and compress in sequence, achieving an ultra-low temperature effect of minus 80 degrees in an indoor environment. Compared with traditional multi-stage compression refrigeration, the structure is simpler and more convenient to maintain.

[0055] Furthermore, based on the refrigerant circuit system composed of the above-mentioned mainstream refrigerant circuit, branch refrigerant circuit and chilled water circuit, a first solenoid valve 212 and a second solenoid valve 213 are also provided in the refrigeration unit 2, wherein: the first solenoid valve 212 is arranged on the connecting pipe between the first electronic expansion valve 211 and the refrigerator indoor unit 3, and the second solenoid valve 213 is arranged on the connecting pipe between the steam separator 216 and the refrigerator indoor unit 3.

[0056] Specifically, the specific operation method of the first solenoid valve 212 and the second solenoid valve 213 includes: after the refrigeration operation is completed, first close the first solenoid valve 212 to prevent the refrigerant from entering the refrigerator unit 3 through the mainstream refrigerant circuit. At this time, the second electronic expansion valve 217 is closed, and the refrigerant does not enter the compressor 207 through the branch refrigerant circuit. Wait for a specified time (generally 30s). At this time, the vapor refrigerant of the refrigerator unit 3 enters the compressor 207 through the vapor separator 216. After the vapor refrigerant of the refrigerator unit 3 is recovered, close the second solenoid valve 213 to complete the overall collection operation of the R23 refrigerant in the system.

[0057] It should be noted that the second solenoid valve 213 here can automatically close after the first solenoid valve 212 is closed for a specified time, and finally shut down the running compressor 207 after the second solenoid valve 213 is closed for a specified time, thereby achieving the effect of automatic recovery of the refrigeration unit.

[0058] At this time, by installing devices such as the first solenoid valve 212 and the second solenoid valve 213 at key positions, and cooperating with the use of the pressure sensor 214 and multiple temperature sensors, it is possible to accurately monitor and control the changes in various parameters in the system, thereby ensuring the safe and stable operation of the entire ultra-low temperature refrigeration unit and avoiding failures caused by improper operation or environmental factors.

[0059] In summary, since the R23 refrigerant has a high pressure at room temperature, the ultra-low temperature refrigeration unit system can quickly and stably recover the refrigerant in the system through the compressor 207, in coordination with the opening and closing of the first solenoid valve 212 and the second solenoid valve 213, thereby improving the system's operating efficiency and safety and extending the service life of the equipment.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0061] In addition, it should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components in a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0062] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their 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 such features. In addition, the meaning of "and / or" appearing throughout the text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes in which A and B are satisfied at the same time. In addition, in the embodiments of the present invention, "multiple" refers to more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that ordinary technicians in this field can implement it. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A cryogenic refrigeration system, comprising a cold source (1), a refrigeration unit (2) and a refrigeration unit (3) connected in sequence via connecting pipes, characterized in that: The cold source (1) is provided with a cold water inlet (101) and a cold water outlet (102), and the cold water inlet (101) and the cold water outlet (102) are both connected to the refrigeration unit (2) via connecting pipes; The interior of the refrigeration unit (2) is composed of a mainstream refrigerant circuit, a branch refrigerant circuit and a chilled water circuit, wherein the mainstream refrigerant circuit, the branch refrigerant circuit and the chilled water circuit cooperate with each other to quickly recover the refrigerant in the system.

2. The ultra-low temperature refrigeration system according to claim 1, wherein: The refrigeration unit (2) is internally provided with a buffer water tank (201), a water pump (202) and a water-fluorine heat exchanger (203) which are sequentially connected via connecting pipes. The buffer water tank (201) is connected to the cold water inlet (101) via a connecting pipe, and the water-fluorine heat exchanger (203) is connected to the cold water outlet (102) via a connecting pipe. The water-fluorine heat exchanger (203) is used to connect to the mainstream refrigerant circuit and perform heat exchange operations. The buffer water tank (201), the water pump (202), the water-fluorine heat exchanger (203), and the connecting pipes therebetween constitute a chilled water circuit.

3. The ultra-low temperature refrigeration system according to claim 2, wherein: The refrigeration unit (2) is further provided with a steam separator (216), a compressor (207), an oil separator (209), a storage tank (210), a liquid reservoir (204), a fluorine-fluorine heat exchanger (205), and a first electronic expansion valve (211) which are sequentially connected via connecting pipes. The connecting pipe portion between the storage tank (210) and the liquid reservoir (204) is connected via the water-fluorine heat exchanger (203) to perform heat exchange operations. The first electronic expansion valve (211) is connected to the refrigerator internal unit (3) via a connecting pipe and is used to transport liquid refrigerant to the refrigerator internal unit (3); the vapor separator (216) is connected to the refrigerator internal unit (3) via a connecting pipe and is used to collect vapor refrigerant from the refrigerator internal unit (3); The steam separator (216), the compressor (207), the oil separator (209), the storage tank (210), the liquid storage tank (204), the fluoro-fluoro heat exchanger (205), the first electronic expansion valve (211), and the connecting pipes therebetween constitute a mainstream refrigerant circuit.

4. The ultra-low temperature refrigeration system according to claim 3, wherein: The connecting pipe between the first electronic expansion valve (211) and the fluorofluoro heat exchanger (205) is further connected to the compressor (207) via a connecting pipe with a second electronic expansion valve (217), and the connecting pipe between the second electronic expansion valve (217) and the compressor (207) is connected via the fluorofluoro heat exchanger (205) to perform heat exchange operations; The connecting pipe with the second electronic expansion valve (217) is provided as a branch refrigerant circuit.

5. The ultra-low temperature refrigeration system according to claim 4, characterized in that: A first solenoid valve (212) is provided on the connecting pipe between the first electronic expansion valve (211) and the refrigerator internal unit (3), and a second solenoid valve (213) is provided on the connecting pipe between the steam separator (216) and the refrigerator internal unit (3).

6. The ultra-low temperature refrigeration system according to claim 4, characterized in that: A pressure sensor (214) and a third temperature sensor (215) are provided on the connecting pipe between the steam separator (216) and the refrigerator internal unit (3).

7. The ultra-low temperature refrigeration system according to claim 4, wherein: A second temperature sensor (208) is provided on the connecting pipe between the compressor (207) and the oil separator (209).

8. The ultra-low temperature refrigeration system according to claim 4, wherein: A first temperature sensor (206) and a fourth temperature sensor (218) are provided on the branch refrigerant circuit, and the first temperature sensor (206) and the fourth temperature sensor (218) are respectively located at two ends of the fluorofluoro heat exchanger (205).

9. The ultra-low temperature refrigeration system according to claim 1, wherein: A connecting valve (31) is provided on the connecting pipe between the refrigeration unit (2) and the refrigeration internal unit (3).

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