A refrigeration system

Abstract

A refrigeration system includes a high-temperature refrigeration loop and a low-temperature refrigeration loop, wherein a phase-change coupling high-efficiency heat exchanger is provided between the high-temperature refrigeration loop and the low-temperature refrigeration loop, the high-temperature refrigeration loop including a first compressor, a condenser, a first throttling device and a flash evaporation and air-increasing module; the low-temperature refrigeration loop includes a second compressor, a second throttling device and an evaporator; when the cascade refrigeration system is in operation, the evaporation process of the high-temperature refrigeration loop and the condensation process of the low-temperature refrigeration loop are coupled in stages, and the evaporator of the high-temperature refrigeration loop and the condenser of the low-temperature refrigeration loop share a phase-change coupling high-efficiency heat exchanger, and by changing the dryness of the first medium and the second medium, constructing a high-efficiency evaporation flow pattern and a high-efficiency condensation flow pattern to improve the heat transfer coefficient of evaporation and condensation, improve the heat transfer efficiency, thereby improving the cooling capacity and system efficiency of the cascade refrigeration system, and can save energy and materials. The present invention has the characteristics of high-efficiency heat transfer, material saving and energy saving.

Description

Technical Field

[0001] The present invention relates to the technical field of refrigeration equipment, and in particular to a refrigeration system. Background Art

[0002] The traditional refrigeration system uses a compressor, condenser, throttling device and evaporator to complete the refrigeration process. When the refrigerant condenses and evaporates, problems such as insufficient evaporation and condensation, poor gas-liquid separation, and low refrigerant dryness may occur. As a result, the refrigerant heat transfer coefficient is poor, which is not conducive to condensation and evaporation heat transfer, resulting in low system cooling capacity and low efficiency.

[0003] Chinese patent document No. CN214841768U disclosed a cascade refrigeration system on November 23, 2021, specifically disclosing a first refrigeration system, a second refrigeration system, a first sensing component, a second sensing component and a control device; the first refrigeration system includes a first compressor, a heat exchanger, an electronic expansion valve and a first evaporator connected in sequence to constitute a refrigeration cycle; the second refrigeration system includes a second compressor, a second condenser and a throttling device; the heat exchanger includes a high-temperature heat exchange flow channel and a low-temperature heat exchange flow channel, and the high-temperature heat exchange flow channel and the first compressor, the electronic expansion valve and the first evaporator constitute a refrigeration cycle; the low-temperature heat exchange flow channel and the second compressor, the second condenser and the throttling device constitute a refrigeration cycle; the first sensing component is located between the first evaporator and the first compressor, for sensing the return air parameters of the first compressor, and the second sensing component is located on the first evaporator, for sensing the evaporation parameters of the first evaporator, and the return air parameters and evaporation parameters are used as the basis for adjusting the opening of the electronic expansion valve, thereby reducing the compression energy consumption of the first compressor, so that the entire cascade refrigeration system is in the most energy-saving state; but this structure has the defects of complex structure and poor energy-saving effect.

[0004] Therefore, further improvements are necessary. Summary of the Invention

[0005] The purpose of the present invention is to provide a refrigeration system with high heat transfer efficiency, material conservation, energy conservation, improved refrigeration capacity and refrigeration efficiency, so as to overcome the shortcomings of the prior art.

[0006] A refrigeration system designed for this purpose is characterized by comprising a high-temperature refrigeration loop and a low-temperature refrigeration loop, wherein a phase-change coupled high-efficiency heat exchanger is provided between the high-temperature refrigeration loop and the low-temperature refrigeration loop. The high-temperature refrigeration loop comprises a first compressor, a condenser, a first throttling device, and a flash vaporization and air-increasing module; wherein the outlet of the first compressor is connected to the inlet of the condenser, the outlet of the condenser is connected to the first throttling device, the first throttling device is respectively connected to the flash vaporization and air-increasing module and the phase-change coupled high-efficiency heat exchanger, the flash vaporization and air-increasing module is connected to the phase-change coupled high-efficiency heat exchanger, and the phase-change coupled high-efficiency heat exchanger is connected to the inlet of the first compressor; and the low-temperature refrigeration loop comprises a second compressor, a second throttling device, and an evaporator; wherein the outlet of the second compressor is connected to the phase-change coupled high-efficiency heat exchanger, the phase-change coupled high-efficiency heat exchanger is connected to the second throttling device, the second throttling device is connected to the inlet of the evaporator, and the outlet of the evaporator is connected to the inlet of the second compressor, so that the first medium of the high-temperature refrigeration loop and the second medium of the low-temperature refrigeration loop exchange heat in the phase-change coupled high-efficiency heat exchanger.

[0007] The phase change coupled high-efficiency heat exchanger includes a first connection port, a second connection port, a shell and tube type header, and a shell and tube heat exchange tube. The first connection port is arranged at one end of the shell and tube type header, the second connection port is arranged at the other end of the shell and tube type header, the shell and tube heat exchange tube is arranged in the shell and tube type header, and the shell and tube heat exchange tube is respectively connected to the first connection port and the second connection port.

[0008] The sleeve-type header includes an outer tube header and an inner tube header, the first connection port includes a first connection port outer tube, the second connection port includes a second connection port outer tube, and the sleeve-type heat exchange tube includes a sleeve-type heat exchange tube outer tube; wherein, the second connection port outer tube is connected to the outer tube header, the first throttling device and the flash gas increase module, and the sleeve-type heat exchange tube outer tube is connected to the outer tube header and the first connection port outer tube.

[0009] The first connection port includes a first connection port inner tube, the second connection port includes a second connection port inner tube, and the shell and tube heat exchange tube includes a shell and tube heat exchange tube inner tube; wherein, the first connection port inner tube is connected to the inner tube header, and the shell and tube heat exchange tube inner tube is connected to the inner tube header and the second connection port inner tube.

[0010] A first partition is provided at the tube-pass separation position on the outer tube header, and a second partition and a third partition are provided between the tube-pass separation positions on the outer tube header and the inner tube header.

[0011] An air regulating chamber is provided between the first partition plate and the second partition plate. The air regulating chamber is provided on the outer pipe header. An air regulating pipe communicating with the outer pipe of the first connecting port is provided on the air regulating chamber.

[0012] The first separator is at least a perforated separator or a centrifugal flow channel separator; the second separator is a non-porous separator; and the third separator is a perforated separator.

[0013] The flash vaporization and gasification module includes a pressure reducing valve, a flash tank and a booster pump. The first throttling device is connected to the inlet of the pressure reducing valve, the outlet of the pressure reducing valve is connected to the inlet of the flash tank, the outlet of the flash tank is connected to the inlet of the booster pump, and the outlet of the booster pump is connected to the outer pipe of the second connecting port.

[0014] The high-temperature refrigeration loop and the low-temperature refrigeration loop are not connected to each other

[0015] The refrigeration system adopted in the present invention effectively overcomes the shortcomings of traditional refrigeration systems in the prior art, such as small cooling capacity, low heat transfer coefficient and low system energy efficiency. Compared with the prior art, the refrigeration system does not adopt the traditional refrigeration system, but couples two refrigeration systems, so that the evaporation process of the high-temperature refrigeration loop and the condensation process of the low-temperature refrigeration loop are coupled in stages, and the evaporator of the high-temperature refrigeration loop and the condenser of the low-temperature refrigeration loop share a phase change coupling high-efficiency heat exchanger. By changing the dryness of the first medium and the second medium, a high-efficiency evaporation flow pattern and a high-efficiency condensation flow pattern are constructed to improve the heat transfer coefficient of evaporation and condensation, improve the heat transfer efficiency, thereby improving the cooling capacity and system efficiency of the cascade refrigeration system, and can save energy and materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. 4 is a flowchart of a refrigeration system according to an embodiment of the present invention.

[0017] Figure 2 This is a schematic diagram of the phase change coupling high-efficiency heat exchange principle according to an embodiment of the present invention.

[0018] Figure 3 This is a diagram of a phase change coupled high-efficiency heat exchange module according to an embodiment of the present invention.

[0019] Figure 4 for Figure 3 Cross-sectional view along the AA direction.

[0020] Figure 5 for Figure 3 Cross-sectional view along the BB direction.

[0021] Figure 6 for Figure 3 Cross-sectional view in CC direction.

[0022] in, Figures 1 to 6 The corresponding relationship between the reference numerals and component names is as follows:

[0023] 1-high-temperature refrigeration loop, 11-first compressor, 12-condenser, 13-first throttling device, 14-flash vaporization and gasification module, 141-pressure reducing valve, 142-flash tank, 143-boosting pump, 2-low-temperature refrigeration loop, 21-second compressor, 22-second throttling device, 23-evaporator, 3-phase change coupled high-efficiency heat exchanger, 31-first connecting port, 311-first connecting port outer tube, 312-first connecting port inner tube, 32-second connecting port, 321-second connecting port outer tube, 322-second connecting port inner tube, 33-tube-type header, 331-outer tube header, 332-inner tube header, 34-tube heat exchange tube. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] See also Figure 1-Figure 3 As shown, in one embodiment, a refrigeration system is provided, including a high-temperature refrigeration loop 1 and a low-temperature refrigeration loop 2, a phase-change coupling high-efficiency heat exchanger 3 is provided between the high-temperature refrigeration loop 1 and the low-temperature refrigeration loop 2, and the high-temperature refrigeration loop 1 includes a first compressor 11, a condenser 12, a first throttling device 13 and a flash vaporization module 14; wherein, the outlet of the first compressor 11 is connected to the inlet of the condenser 12, the outlet of the condenser 12 is connected to the first throttling device 13, the first throttling device 13 is connected to the flash vaporization module 14 and the phase-change coupling high-efficiency heat exchanger 3 respectively, and the flash vaporization module 14 is connected to the phase-change coupling high-efficiency heat exchanger 3. The high-efficiency heat exchanger 3 is coupled to the high-efficiency heat exchanger 3, and the phase-change coupled high-efficiency heat exchanger 3 is connected to the inlet of the first compressor 11; the low-temperature refrigeration loop 2 includes a second compressor 21, a second throttling device 22 and an evaporator 23; wherein, the outlet of the second compressor 21 is connected to the phase-change coupled high-efficiency heat exchanger 3, the phase-change coupled high-efficiency heat exchanger 3 is connected to the second throttling device 22, the second throttling device 22 is connected to the inlet of the evaporator 23, and the outlet of the evaporator 23 is connected to the inlet of the second compressor 21, so that the first medium of the high-temperature refrigeration loop 1 and the second medium of the low-temperature refrigeration loop 2 exchange heat in the phase-change coupled high-efficiency heat exchanger 3.

[0026] Specifically, the cascade refrigeration system continuously constructs an efficient condensation heat transfer zone of the low-temperature refrigeration loop, and constructs and maintains an efficient evaporation heat transfer zone of the high-temperature refrigeration loop in advance, and couples the two efficient phase change heat transfer zones for heat exchange, thereby improving the heat transfer coefficient and the system cooling capacity, thereby improving the efficiency of the cascade refrigeration system.

[0027] Further, the first compressor 11 in the high-temperature refrigeration loop 1 is connected to the first throttling device 13 through the condenser 12, and the first throttling device 13 is respectively connected to the phase change coupling high-efficiency heat exchanger 3 and the flash vaporization increase module 14, and the flash vaporization increase module 14 is connected to the phase change coupling high-efficiency heat exchanger 3, and the phase change coupling high-efficiency heat exchanger 3 is connected to the first compressor 11; the second compressor 21 in the low-temperature refrigeration loop 2 is connected to the phase change coupling high-efficiency heat exchanger 3, and the phase change coupling high-efficiency heat exchanger 3 is connected to the evaporator 23 through the second throttling device 22, and the evaporator 23 is connected to the second compressor 11; when the cascade refrigeration system is running, the first throttling device 13 in the high-temperature refrigeration loop 1 is respectively connected to the flash vaporization increase module 14 and the phase change coupling high-efficiency heat exchanger 3, and the flash vaporization increase module 14 The first medium is connected to the phase change coupling high-efficiency heat exchanger 3, and the first medium is in the first compressor 11, the condenser 12, the first throttling device 13, the phase change coupling high-efficiency heat exchanger 3 and the flash evaporation and gasification module 14 to increase the dryness of the first medium for evaporation heat exchange; the second compressor 21 in the low-temperature refrigeration loop 2 is connected to the phase change coupling high-efficiency heat exchanger 3, and the phase change coupling high-efficiency heat exchanger 3 is connected to the second throttling device 22. The second medium is in the second compressor 21, the phase change coupling high-efficiency heat exchanger 3, the second throttling device 22, the evaporator 23 and the third partition 6 to increase the dryness of the second medium for condensation heat exchange, thereby realizing efficient heat exchange between the first medium and the second medium, and ultimately making the cascade refrigeration system efficient in heat exchange, improving the system cooling capacity and system efficiency, saving energy and saving costs.

[0028] It should be noted that the phase change coupled high-efficiency heat exchanger 3 needs to obtain part of the superheated gaseous refrigerant in advance and mix it with the remaining low-dryness refrigerant to construct an efficient evaporation flow pattern; at the same time, when the second medium of the low-temperature refrigeration loop 2 enters the phase change coupled high-efficiency heat exchanger 3 for condensation, it is continuously discharged through the third partition 6 to maintain an efficient condensation flow pattern, and an efficient heat exchange process is constructed in the phase change coupled high-efficiency heat exchanger 3 to couple the efficient condensation flow pattern of the low-temperature cycle with the efficient evaporation flow pattern of the high-temperature cycle.

[0029] Furthermore, the first throttling device 13 and the second throttling device 22 are both throttle valves.

[0030] See also Figure 3 As shown, the phase change coupled high-efficiency heat exchanger 3 includes a first connection port 31, a second connection port 32, a shell and tube type header 33 and a shell and tube heat exchange tube 34. The first connection port 31 is arranged at one end of the shell and tube type header 33, the second connection port 32 is arranged at the other end of the shell and tube type header 33, and the shell and tube heat exchange tube 34 is arranged in the shell and tube type header 33, and the shell and tube heat exchange tube 34 is respectively connected to the first connection port 31 and the second connection port 32.

[0031] See also Figure 3-Figure 6As shown, the sleeve-type header 33 includes an outer tube header 331 and an inner tube header 332, the first connection port 31 includes a first connection port outer tube 311, the second connection port 32 includes a second connection port outer tube 321, and the sleeve-type heat exchange tube 34 includes a sleeve-type heat exchange tube outer tube 341; wherein, the second connection port outer tube 321 is connected to the outer tube header 331, the first throttling device 13 and the flash vaporization module 14, and the sleeve-type heat exchange tube outer tube 341 is connected to the outer tube header 331 and the first connection port outer tube 311.

[0032] See also Figure 3-Figure 6 As shown, the first connection port 31 includes a first connection port inner tube 312, the second connection port 32 includes a second connection port inner tube 322, and the shell and tube heat exchange tube 34 includes a shell and tube heat exchange tube inner tube 342; wherein, the first connection port inner tube 312 is connected to the inner tube header 332, and the shell and tube heat exchange tube inner tube 342 is connected to the inner tube header 332 and the second connection port inner tube 322.

[0033] See also Figure 3 As shown, a first partition plate 4 is provided at the tube-pass separation position on the outer tube header 331 , and a second partition plate 5 and a third partition plate 6 are provided between the tube-pass separation positions on the outer tube header 331 and the inner tube header 332 .

[0034] Specifically, the first partition 4 is used to adjust the dryness of the evaporating fluid, and the flash evaporation and aeration module 14 is used to increase the dryness of the first medium, so that the first medium in the high-temperature refrigeration loop 1 is in a high-efficiency evaporation flow pattern; the third partition 6 is used to adjust the dryness of the condensing fluid, so that the second medium in the low-temperature refrigeration loop 2 is in a high-efficiency condensation flow pattern.

[0035] See also Figure 3 As shown, an air regulating chamber 7 is provided between the first partition plate 4 and the second partition plate 5 . The air regulating chamber is provided on the outer pipe header 331 . An air regulating pipe communicating with the first connecting port outer pipe 311 is provided on the air regulating chamber 7 .

[0036] Furthermore, the first partition plate 4 is at least a perforated partition plate or a centrifugal flow channel partition plate; the second partition plate 5 is a non-porous partition plate; and the third partition plate 6 is a perforated partition plate.

[0037] See also Figure 1 and Figure 3 As shown, the flash vaporization and gasification module 14 includes a pressure reducing valve 141, a flash tank 142 and a boosting pump 143. The first throttling device 13 is connected to the inlet of the pressure reducing valve 141, the outlet of the pressure reducing valve 141 is connected to the inlet of the flash tank 142, the outlet of the flash tank 142 is connected to the inlet of the boosting pump 143, and the outlet of the boosting pump 143 is connected to the second connecting port outer pipe 321.

[0038] The high-temperature refrigeration loop 1 and the low-temperature refrigeration loop 2 are not connected to each other.

[0039] See also Figure 2 As shown in FIG5 , it can be seen from the condensation curve and the evaporation curve that when the dryness of the first medium and the second medium is between 0 and 1, the dryness and heat transfer coefficient of the first medium and the second medium are increased. By increasing the dryness of the first medium and the second medium, the evaporation process and the condensation process of the first medium and the second medium are both in the high-efficiency heat exchange zone, thereby improving the heat transfer coefficient, thereby improving the cooling capacity and system energy efficiency of the refrigeration system.

[0040] The detailed working principle of this refrigeration system:

[0041] When the cascade refrigeration system is running:

[0042] In the high-temperature refrigeration loop, the first medium is discharged from the first compressor 11 and enters the condenser 12. After passing through the first throttling device 13, it is divided into two branches. The first branch enters the flash vaporization and gasification module 14. The liquid first medium is throttled by the pressure reducing valve 141 and flashed in the flash tank 142 to obtain a large amount of low-pressure gaseous first medium. The low-pressure gaseous first medium is pressurized by the booster pump 143 and enters the phase change coupling high-efficiency heat exchanger 3; the second branch directly enters the phase change coupling high-efficiency heat exchanger 3. The superheated gaseous first medium after flash vaporization and the remaining low-dryness first medium are in phase The variable coupling high-efficiency heat exchanger 3 merges to form a high-efficiency evaporation flow pattern. The merged first medium enters the outer tube header 331 through the second connecting port outer tube 311 and enters the outer tube 341 of the double-tube heat exchange tube under the blocking effect of the third partition 6. It efficiently exchanges heat with the second medium in the inner tube 342 of the double-tube heat exchange tube. When passing through the first partition 4, part of the gaseous first medium is separated and enters the air conditioning chamber 7 between the first partition 4 and the second partition 5. Then, it enters the first connecting port outer tube 311 through the air conditioning pipe and finally returns to the inlet of the first compressor 11 and repeats the cycle.

[0043] In the low-temperature refrigeration loop, the second medium enters the phase-change coupled high-efficiency heat exchanger 3 after being discharged from the second compressor 21. The second medium enters the inner tube header 332 through the inner tube 312 of the first connecting port. Due to the blocking effect of the second partition 5 and the gas-liquid separation effect of the third partition 6 in the inner tube header 332, the condensate is discharged from the small holes of the third partition 6. The condensate no longer enters the double-tube heat exchange tube 34, thereby forming a high-dryness and high-efficiency condensation flow pattern. The high-dryness second medium enters the inner tube 342 of the double-tube heat exchange tube, efficiently exchanges heat with the first medium in the outer tube 341 of the double-tube heat exchange tube, and then enters the second throttling device 22 through the inner tube 322 of the second connecting port. Finally, the second medium returns to the inlet of the second compressor 21 through the evaporator 23 and repeats the cycle.

[0044] Among them, the outer tube 341 of the shell and tube heat exchange tube in the phase change coupled high-efficiency heat exchanger 3 is connected to the high-temperature refrigeration loop 1, which is conducive to the evaporation and heat absorption of the first medium. It can absorb the heat released by the condensation of the second medium on the inner tube 342 of the shell and tube heat exchange tube, and can also absorb heat from the outside air.

[0045] The above is a preferred embodiment of the present invention, which illustrates and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A refrigeration system comprising a high-temperature refrigeration loop (1) and a low-temperature refrigeration loop (2), characterized in that: A phase-change coupled high-efficiency heat exchanger (3) is provided between the high-temperature refrigeration loop (1) and the low-temperature refrigeration loop (2), and the high-temperature refrigeration loop (1) comprises a first compressor (11), a condenser (12), a first throttling device (13) and a flash vaporization and gasification module (14); wherein the outlet of the first compressor (11) is connected to the inlet of the condenser (12), the outlet of the condenser (12) is connected to the first throttling device (13), the first throttling device (13) is respectively connected to the flash vaporization and gasification module (14) and the phase-change coupled high-efficiency heat exchanger (3), the flash vaporization and gasification module (14) is connected to the phase-change coupled high-efficiency heat exchanger (3), and the phase-change coupled high-efficiency heat exchanger (14) is connected to the phase-change coupled high-efficiency heat exchanger (14). (3) is connected to the inlet of the first compressor (11); the low-temperature refrigeration loop (2) includes a second compressor (21), a second throttling device (22) and an evaporator (23); wherein the outlet of the second compressor (21) is connected to the phase-change coupling high-efficiency heat exchanger (3), the phase-change coupling high-efficiency heat exchanger (3) is connected to the second throttling device (22), the second throttling device (22) is connected to the inlet of the evaporator (23), and the outlet of the evaporator (23) is connected to the inlet of the second compressor (21), so that the first medium of the high-temperature refrigeration loop (1) and the second medium of the low-temperature refrigeration loop (2) exchange heat in the phase-change coupling high-efficiency heat exchanger (3); The phase-change coupled high-efficiency heat exchanger (3) comprises a first connection port (31), a second connection port (32), a sleeve-type header (33), and a sleeve-type heat exchange tube (34); the first connection port (31) is arranged at one end of the sleeve-type header (33), the second connection port (32) is arranged at the other end of the sleeve-type header (33), the sleeve-type heat exchange tube (34) is arranged in the sleeve-type header (33), and the sleeve-type heat exchange tube (34) is communicated with the first connection port (31) and the second connection port (32), respectively; The sleeve-type header (33) comprises an outer tube header (331) and an inner tube header (332); the first connection port (31) comprises a first connection port outer tube (311); the second connection port (32) comprises a second connection port outer tube (321); and the sleeve-type heat exchange tube (34) comprises a sleeve-type heat exchange tube outer tube (341); wherein the second connection port outer tube (321) is in communication with the outer tube header (331), the first throttling device (13), and the flash vaporization and gasification module (14); and the sleeve-type heat exchange tube outer tube (341) is in communication with the outer tube header (331) and the first connection port outer tube (311); The flash vaporization and gasification module (14) comprises a pressure reducing valve (141), a flash tank (142) and a boosting pump (143); the first throttling device (13) is connected to the inlet of the pressure reducing valve (141); the outlet of the pressure reducing valve (141) is connected to the inlet of the flash tank (142); the outlet of the flash tank (142) is connected to the inlet of the boosting pump (143); and the outlet of the boosting pump (143) is connected to the second connecting port outer pipe (321); The first connection port (31) includes a first connection port inner tube (312), the second connection port (32) includes a second connection port inner tube (322), and the shell-and-tube heat exchange tube (34) includes a shell-and-tube heat exchange tube inner tube (342); wherein the first connection port inner tube (312) is connected to the inner tube header (332), and the shell-and-tube heat exchange tube inner tube (342) is connected to the inner tube header (332) and the second connection port inner tube (322).

2. The refrigeration system according to claim 1, characterized in that: A first partition plate (4) is provided at the tube-pass separation position on the outer tube header (331), and a second partition plate (5) and a third partition plate (6) are provided between the tube-pass separation positions on the outer tube header (331) and the inner tube header (332).

3. The refrigeration system according to claim 2, wherein: An air conditioning chamber (7) is provided between the first partition plate (4) and the second partition plate (5). The air conditioning chamber (7) is arranged on the outer pipe header (331). An air conditioning pipe communicating with the first connecting port outer pipe (311) is provided on the air conditioning chamber (7).

4. The refrigeration system according to claim 2, wherein: The first partition plate (4) is at least a perforated partition plate or a centrifugal flow channel partition plate; the second partition plate (5) is a non-porous partition plate; and the third partition plate (6) is a perforated partition plate.

5. The refrigeration system according to claim 1, wherein: The high-temperature refrigeration loop (1) and the low-temperature refrigeration loop (2) are not connected to each other.

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