Refrigerator

Abstract

This invention discloses a refrigeration machine, relating to the field of absorption refrigeration technology. In the refrigeration machine, a generator has a first housing with a first cavity, where the generator vaporizes a solvent; a condenser has a second housing with a second cavity, disposed within the first cavity, and the first and second cavities are connected, where the condenser liquefies the gaseous solvent generated by the generator; an evaporator has a third housing with a third cavity; a connecting pipe connects the second and third cavities, where the evaporator vaporizes the liquid solvent generated by the condenser and provides external cooling; an absorber has a fourth housing with a fourth cavity, where the third housing is disposed within the fourth housing, and the third and fourth cavities are connected, where the absorber liquefies the gaseous solvent generated by the evaporator. The technical solution provided by this invention achieves the effect of reducing volume by placing the condenser inside the generator and the evaporator inside the absorber.

Description

Technical Field

[0001] This invention relates to the field of absorption refrigeration technology, and particularly to a refrigeration machine. Background Technology

[0002] Traditional oilfields generate large amounts of geothermal fluids during extraction. In the past, due to a lack of efficient and economical methods for utilization, these valuable medium- and low-temperature heat sources were often considered a "burden," requiring cooling towers and other methods for heat dissipation before reinjection. This not only wasted thermal energy but also consumed additional electricity and water resources. Meanwhile, oilfield production and living facilities have significant cooling needs. Lithium bromide absorption chillers provide the perfect technological link between waste heat and demand.

[0003] Currently, conventional absorption chillers use a parallel, straight-tube design. As the cooling capacity increases, the required heat exchange area grows, and the volume of each heat and mass transfer device increases accordingly. This cumulative increase causes the unit's size to expand rapidly with increasing cooling capacity, increasing the space requirements for installation. Especially for units with very small cooling capacities, the parallel heat exchanger design prevents a significant reduction in unit size, making them too bulky and lacking competitive advantage compared to compression chillers. Summary of the Invention

[0004] The main objective of this invention is to propose a refrigeration machine that addresses the problems of large size and high space requirements for installation.

[0005] To achieve the above objectives, the refrigeration unit proposed in this invention includes: a generator, a condenser, an evaporator, a connecting pipe, and an absorber; the generator has a first housing, the first housing having a first cavity, and a solution is introduced into the first housing, the generator being used to vaporize the solvent; the condenser has a second housing, the second housing having a second cavity disposed within the first cavity, the first cavity being connected to the second cavity, the condenser being used to liquefy the gaseous solvent generated by the generator; the evaporator has a third housing, the third housing having a third cavity; the connecting pipe connects the second cavity and the third cavity to introduce the liquid solvent into the third cavity, the evaporator being used to vaporize the liquid solvent generated by the condenser and to provide external cooling; the absorber has a fourth housing, the fourth housing having a fourth cavity, the third housing being disposed within the fourth housing, the third cavity being connected to the fourth cavity, the absorber being used to liquefy the gaseous solvent generated by the evaporator.

[0006] In one embodiment, the generator further includes:

[0007] The first coil is disposed in the first cavity, extends in the vertical direction and is wrapped around the outer periphery of the second shell. The inlet and outlet ends of the first coil both extend outside the first shell. The first coil is used to introduce high-temperature liquid. The first spray pipe has a first pipe section and a second pipe section. The first pipe section is arranged in a ring shape and is located on the upper side of the first coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the first pipe section. One end of the second pipe section is connected to the first pipe section, and the other end is located at the bottom of the first cavity.

[0008] In one embodiment, the condenser includes a second coil located within the second cavity. The second coil extends vertically and is circumferentially arranged corresponding to the second housing. The second coil is used to allow the introduction of a cryogenic liquid.

[0009] In one embodiment, the evaporator includes: The third coil is disposed in the third cavity, extends in the vertical direction and is circumferentially arranged corresponding to the third housing. The inlet and outlet ends of the third coil both extend to the outside of the fourth housing. The third coil is used to introduce high-temperature liquid. The third spray pipe has a third pipe section and a fourth pipe section. The third pipe section is arranged in a ring and is located on the upper side of the third coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the third pipe section. One end of the fourth pipe section is connected to the third pipe section, and the other end is located at the bottom of the third cavity. A first circulation pump, installed in the fourth pipe section, is used to pump the liquid solvent to the third pipe section.

[0010] In one embodiment, the absorber includes: The fourth coil is disposed in the fourth cavity, extends in the vertical direction and is wrapped around the outer periphery of the third shell. The inlet and outlet ends of the fourth coil both extend outside the fourth shell. The fourth coil is used to introduce cryogenic liquid. The fourth spray pipe has a fifth pipe section and a sixth pipe section. The fifth pipe section is arranged in a ring and is located on the upper side of the fourth coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the fifth pipe section. One end of the sixth pipe section is connected to the fifth pipe section, and the other end is located at the bottom of the fourth cavity. A second circulation pump, installed in the sixth pipe section, is used to pump the liquid solvent to the fifth pipe section.

[0011] In one embodiment, the refrigeration unit further includes a heat exchanger disposed between the second pipe section and the sixth pipe section.

[0012] In one embodiment, the refrigeration unit includes: The first storage tank, located in the fourth pipe section, is used to store the liquid solvent; The second storage tank, located in the sixth pipe section, is used to store lithium bromide solution.

[0013] In one embodiment, the second housing is provided with an upward opening to form the second cavity, and the third housing is provided with an upward opening to form the third cavity; the refrigerator further includes a connecting rod that extends in a vertical direction and is fixedly connected to the first housing, the second housing, the third housing, and the fourth housing, respectively.

[0014] In one embodiment, the generator is disposed on the upper side of the absorber.

[0015] In one embodiment, the refrigerator further includes a vacuum pump, which is connected to the first cavity and the fourth cavity via pipes.

[0016] The technical solution of the present invention achieves the effect of reducing volume by placing the condenser inside the generator and the evaporator inside the absorber. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a structure of an embodiment of the refrigeration machine provided by the present invention.

[0019] Explanation of icon numbers: 100. Refrigeration unit; 1. Generator; 11. First shell; 12. First coil; 13. First spray pipe; 131. First pipe section; 132. Second pipe section; 2. Condenser; 21. Second shell; 22. Second coil; 3. Evaporator; 31. Third shell; 32. Third coil; 33. Third spray pipe; 331. Third pipe section; 332. Fourth pipe section; 34. First circulation pump; 35. First storage tank; 4. Absorber; 41. Fourth shell; 42. Fourth coil; 43. Fourth spray pipe; 431. Fifth pipe section; 432. Sixth pipe section; 44. Second circulation pump; 45. Second storage tank; 5. Connecting pipe; 6. Heat exchanger; 7. Connecting rod; 8. Vacuum pump.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] Currently, conventional absorption chillers use a parallel, straight-tube design. As the cooling capacity increases, the required heat exchange area grows, and the volume of each heat and mass transfer device increases accordingly. This cumulative increase causes the unit's size to expand rapidly with increasing cooling capacity, increasing the space requirements for installation. Especially for units with very small cooling capacities, the parallel heat exchanger design prevents a significant reduction in unit size, making them too bulky and lacking competitive advantage compared to compression chillers.

[0025] This invention proposes a refrigeration machine.

[0026] Please see Figure 1In one embodiment of the present invention, the refrigeration unit 100 includes: a generator 1, a condenser 2, an evaporator 3, a connecting pipe 5, and an absorber 4; the generator 1 has a first housing 11, the first housing 11 having a first cavity, the first housing 11 being used to introduce a solution, and the generator 1 being used to vaporize the solvent; the condenser 2 has a second housing 21, the second housing 21 having a second cavity disposed within the first cavity, the first cavity being connected to the second cavity, and the condenser 2 being used to liquefy the gaseous solvent generated by the generator 1; The evaporator 3 has a third housing 31, which has a third cavity; the connecting pipe 5 connects the second cavity and the third cavity to introduce the liquid solvent into the third cavity. The evaporator 3 is used to vaporize the liquid solvent generated by the condenser 2 and to provide external cooling. The absorber 4 has a fourth housing 41, which has a fourth cavity. The third housing 31 is disposed inside the fourth housing 41, and the third cavity is connected to the fourth cavity. The absorber 4 is used to liquefy the gaseous solvent generated by the evaporator 3.

[0027] In the technical solution of this invention, generator 1 has a first housing 11 and a first cavity. A dilute lithium bromide solution is introduced into the first housing 11 and heated by geothermal fluid from an oilfield, causing the solvent (water) in the solution to vaporize. Condenser 2 has a second housing 21 and a second cavity. Condenser 2 is nested within the first cavity of generator 1, and the first cavity is connected to the second cavity. Gaseous solvent enters the interior of condenser 2, which condenses the gaseous solvent generated by generator 1 into a liquid state. Evaporator 3 has a third housing 31 and a third cavity, connected to the second cavity of condenser 2 via a connecting pipe 5. Liquid solvent enters evaporator 3, vaporizes, and absorbs heat, achieving external cooling. Absorber 4 has a fourth housing 41 and a fourth cavity. Evaporator 3 is nested within the fourth cavity of absorber 4, and the third cavity is connected to the fourth cavity. Concentrated lithium bromide solution in absorber 4 reabsorbs the gaseous solvent generated by evaporator 3. After absorbing the solvent, the concentrated lithium bromide solution forms a dilute lithium bromide solution that can be used by generator 1, completing the cycle. In this technical solution, by integrating the condenser 2 into the generator 1 cavity and the evaporator 3 into the absorber 4 cavity, the traditional parallel arrangement structure is eliminated, significantly reducing the overall size and floor space of the unit. Compared to the traditional parallel arrangement structure, at least the volume and corresponding floor space of the evaporator 3 and condenser 2 are reduced. This results in a higher degree of integration and a more compact form of the refrigerator 100, addressing the issue of the large size of existing refrigerators 100.

[0028] To utilize geothermal fluid from the oilfield to heat and vaporize the solvent (water) in the solution, the generator 1 further includes: a first coil 12 and a first spray pipe 13. The first coil 12 is disposed within the first cavity, extending vertically and wrapping around the outer periphery of the second housing 21. The first coil 12 is spirally arranged, with both its inlet and outlet ends extending outside the first housing 11. High-temperature liquid (geothermal fluid from the oilfield) is introduced into the first coil 12. To allow the dilute lithium bromide solution to contact the first coil 12 and evaporate the solvent under the heat of the high-temperature liquid, the first spray pipe 13 has a first pipe section 131 and a second pipe section. 132. The first pipe section 131 is arranged in a ring shape and is located on the upper side of the first coil 12. The diameter of the ring corresponds to the diameter of the first coil 12. Multiple spray nozzles are arranged circumferentially on the lower side of the first pipe section 131. The dilute lithium bromide solution is sprayed onto the first coil 12 and evaporates upon heating. Since only a small portion of the solvent in the dilute lithium bromide solution can evaporate after one spray, one end of the second pipe section 132 is connected to the first pipe section 131, and the other end is located at the bottom of the first cavity. The unevaporated solvent can be returned to the first pipe section 131 through the second pipe section 132 for repeated spraying.

[0029] To liquefy the gaseous solvent entering the second chamber, the condenser 2 includes a second coil 22 located within the second chamber. The second coil 22 extends vertically and is circumferentially arranged around the second housing 21. A low-temperature liquid is introduced into the second coil 22. The second coil 22 is spirally arranged to increase the contact area, so that the high-temperature gaseous solvent will liquefy upon contact with the lower-temperature second coil 22.

[0030] The liquefied solvent enters the third chamber through the connecting pipe 5. The evaporator 3 includes a third coil 32 and a third spray pipe 33. The third coil 32 is disposed in the third chamber, extending vertically and circumferentially around the third housing 31. The third coil 32 is spirally arranged, with both its inlet and outlet extending outside the fourth housing 41. The third coil 32 is used to introduce high-temperature liquid. The third spray pipe 33 has a third section 331 and a fourth section 332. The third section 331 is annularly arranged on the upper side of the third coil 32. Multiple spray nozzles are spaced circumferentially on the lower side of the third section 331. One end of the fourth section 332 is connected to the third section 331, and the other end is disposed at the bottom of the third chamber. A first circulation pump 34 is installed in the fourth section 332 to pump the liquid solvent to the third section 331. Under the action of the first circulation pump 34, the liquid solvent in the third chamber is pumped through the fourth pipe section 332 to the third pipe section 331 on the upper side of the third coil 32, and then evenly sprayed onto the surface of the third coil 32 below through the spray nozzle on the lower side of the third pipe section 331, increasing the contact area between the liquid solvent and the third coil 32, promoting the rapid and uniform vaporization of the liquid solvent, and further improving the heat exchange and refrigeration efficiency of the evaporator 3.

[0031] To absorb the solvent evaporated from the generator 1, the absorber 4 includes a fourth coil 42, a fourth spray pipe 43, and a second circulation pump 44. The fourth coil 42 is disposed in the fourth cavity, extends vertically and wraps around the outer periphery of the third housing 31, and is arranged in a spiral shape. The inlet and outlet ends of the fourth coil 42 extend outside the fourth housing 41, and the fourth coil 42 is used to introduce cryogenic liquid. The fourth spray pipe 43 has a fifth pipe section 431 and a sixth pipe section 432. The fifth pipe section 431 is arranged in a ring shape and is located on the upper side of the fourth coil 42. Multiple spray nozzles are arranged circumferentially at intervals on the lower side of the fifth pipe section 431. One end of the sixth pipe section 432 is connected to the fifth pipe section 431, and the other end is located at the bottom of the fourth cavity. The cryogenic liquid exchanges heat with the concentrated lithium bromide solution in the fourth cavity to reduce the temperature of the concentrated solution and improve its absorption efficiency of the gaseous solvent (water vapor) generated by the evaporator 3, ensuring a stable and efficient absorption process. The second circulation pump 44 is installed in the sixth pipe section 432 and is used to pump the liquid solvent to the fifth pipe section 431. Its core function is to provide power for the transport of concentrated lithium bromide solution, stably pumping the concentrated solution from the bottom of the fourth chamber to the fifth pipe section 431, and then evenly spraying it onto the surface of the fourth coil 42 below through the spray nozzle on the lower side of the fifth pipe section 431. This increases the contact area between the concentrated solution and the fourth coil 42, promotes rapid cooling of the concentrated solution, further improves the absorption efficiency of the absorber 4, and ensures stable operation of the closed-loop refrigeration cycle. The surfaces of the first coil 12, the second coil 22, the third coil 32, and the fourth coil 42 can be knurled to form a textured surface, thereby increasing the contact area, improving the heat and mass transfer coefficient, and facilitating heat exchange. For the installation of each coil, multiple fixing blocks are spaced apart inside the outer shell, with grooves on the fixing blocks. The coils are positioned and installed in the grooves of these fixing blocks.

[0032] In one embodiment, the chiller 100 further includes a heat exchanger 6, which is disposed between the second pipe section 132 and the sixth pipe section 432. The function of the heat exchanger 6 is to recover waste heat and improve energy utilization: the second pipe section 132 carries a lithium bromide dilute solution that has not been fully heated at the bottom of the generator 1. This solution still carries some waste heat after the initial heat exchange (the heat has not been completely transferred to the solvent to achieve vaporization); the sixth pipe section 432 carries a lithium bromide dilute solution formed after the absorber 4 absorbs gaseous solvent (the concentration decreases and the temperature is relatively low after the absorption process). Through the heat transfer of the heat exchanger 6, the waste heat of the dilute solution in the second pipe section 132 can be fully recovered and used to preheat the low-temperature dilute solution in the sixth pipe section 432, realizing the reuse of waste heat, avoiding heat energy waste, and meeting the core needs of energy conservation and consumption reduction in oil fields.

[0033] In one embodiment, the refrigeration unit 100 includes a first storage tank 35 and a second storage tank 45. The first storage tank 35 is fixedly disposed on the fourth section 332 of the third spray pipe 33 of the evaporator 3. Its core function is to store the liquid solvent transported in the fourth section 332, thereby achieving buffer storage of the liquid solvent and preventing fluctuations in the liquid solvent transport from affecting the spray vaporization effect of the evaporator 3, ensuring the stability of the refrigeration process of the evaporator 3. At the same time, the amount of liquid solvent transported can be adjusted according to the refrigeration demand. The second storage tank 45 is fixedly disposed on the sixth section 432 of the fourth spray pipe 43 of the absorber 4. Its core function is to store the lithium bromide solution (including the dilute solution formed after absorbing gaseous solvent) transported in the sixth section 432, thereby achieving buffer storage and stable transport of the lithium bromide solution, preventing fluctuations in the solution transport from affecting the spray absorption effect of the absorber 4. At the same time, it can provide a stable solution reserve for the solution circulation of the entire refrigeration cycle, ensuring the smooth operation of the closed-loop refrigeration cycle.

[0034] In one embodiment, the second housing 21 is configured to open upwards to form the second cavity, and the third housing 31 is configured to open upwards to form the third cavity. The refrigerator 100 also includes a connecting rod 7, which extends vertically and is fixedly connected to the first housing 11, the second housing 21, the third housing 31, and the fourth housing 41, respectively. The upward openings of the second housing 21 and the third housing 31 optimize the fluid flow path and improve circulation efficiency. The addition of the vertically extending connecting rod 7 enables the four housings to be fixed as a single unit, enhancing the overall structural stability, preventing housing swaying during operation, and facilitating installation and transportation of the entire unit, thus adapting to the needs of oilfield on-site operation and maintenance.

[0035] Furthermore, the generator 1 is positioned above the absorber 4. Therefore, the actual floor space of the refrigerator 100 is roughly equivalent to that of the absorber 4, further reducing the floor space required. Additionally, the placement of the generator 1 above the absorber 4 facilitates the transfer of liquid to the evaporator 3 via the connecting pipe 5.

[0036] Because a cylindrical shell can withstand more pressure than a rectangular shell, both the first shell 11 and the fourth shell 41 are made into cylindrical shapes. The purpose is to use thinner steel plates to withstand the same pressure, thereby achieving the goals of weight reduction, material saving, and cost reduction.

[0037] To reduce pressure, lower the solvent boiling point, and facilitate solvent evaporation, the refrigerator 100 also includes a vacuum pump 8, which is connected to the first chamber and the fourth chamber via pipes. The vacuum pump 8 extracts non-condensable gases (such as air) from the first and fourth chambers, creating a near-vacuum environment within the chambers. The refrigeration efficiency of the lithium bromide absorption refrigerator 100 is closely related to the chamber vacuum level. By extracting air through the vacuum pump 8, non-condensable gases are minimized from hindering heat and mass transfer processes, ensuring efficient solvent vaporization, condensation, and absorption, further guaranteeing the overall refrigeration efficiency and operational stability. For the liquefied solvent entering the third chamber via the connecting pipe 5, liquid transfer can be achieved by installing a drive pump on the connecting pipe 5, or by utilizing the pressure difference between the second and third chambers.

[0038] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A refrigerator characterized by comprising: include: A generator has a first housing with a first cavity for introducing a solution into the housing, and the generator is used to vaporize the solvent. A condenser has a second housing, the second housing having a second cavity disposed within a first cavity, the first cavity being connected to the second cavity, the condenser being used to liquefy the gaseous solvent generated by the generator; An evaporator having a third housing, the third housing having a third cavity; A connecting pipe connects the second cavity and the third cavity to introduce the liquid solvent into the third cavity. The evaporator is used to vaporize the liquid solvent generated by the condenser and to provide external cooling. An absorber has a fourth housing with a fourth cavity, a third housing disposed within the fourth housing, and the third cavity being connected to the fourth cavity. The absorber is used to liquefy the gaseous solvent generated by the evaporator.

2. The refrigerator of claim 1, wherein, The generator also includes: The first coil is disposed in the first cavity, extends in the vertical direction and is wrapped around the outer periphery of the second shell. The inlet and outlet ends of the first coil both extend outside the first shell. The first coil is used to introduce high-temperature liquid. The first spray pipe has a first pipe section and a second pipe section. The first pipe section is arranged in a ring shape and is located on the upper side of the first coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the first pipe section. One end of the second pipe section is connected to the first pipe section, and the other end is located at the bottom of the first cavity.

3. The refrigerator of claim 2, wherein, The condenser includes a second coil located within the second cavity. The second coil extends vertically and is circumferentially arranged corresponding to the second housing. The second coil is used to introduce cryogenic liquid.

4. The refrigerator of claim 3, wherein The evaporator includes: The third coil is disposed in the third cavity, extends in the vertical direction and is circumferentially arranged corresponding to the third housing. The inlet and outlet ends of the third coil both extend to the outside of the fourth housing. The third coil is used to introduce high-temperature liquid. The third spray pipe has a third pipe section and a fourth pipe section. The third pipe section is arranged in a ring and is located on the upper side of the third coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the third pipe section. One end of the fourth pipe section is connected to the third pipe section, and the other end is located at the bottom of the third cavity. A first circulation pump, installed in the fourth pipe section, is used to pump the liquid solvent to the third pipe section.

5. The refrigerator of claim 4, wherein, The absorber includes: The fourth coil is disposed in the fourth cavity, extends in the vertical direction and is wrapped around the outer periphery of the third shell. The inlet and outlet ends of the fourth coil both extend outside the fourth shell. The fourth coil is used to introduce cryogenic liquid. The fourth spray pipe has a fifth pipe section and a sixth pipe section. The fifth pipe section is arranged in a ring and is located on the upper side of the fourth coil. Multiple spray nozzles are arranged at intervals along the circumference on the lower side of the fifth pipe section. One end of the sixth pipe section is connected to the fifth pipe section, and the other end is located at the bottom of the fourth cavity. A second circulation pump, installed in the sixth pipe section, is used to pump the liquid solvent to the fifth pipe section.

6. The refrigerator of claim 5, wherein, The refrigeration unit also includes a heat exchanger, which is disposed between the second pipe section and the sixth pipe section.

7. The refrigerator of claim 5, wherein The refrigeration unit includes: The first storage tank, located in the fourth pipe section, is used to store the liquid solvent; The second storage tank, located in the sixth pipe section, is used to store lithium bromide solution.

8. The chiller of claim 1, wherein, The second housing has an upward opening to form the second cavity, and the third housing has an upward opening to form the third cavity; the refrigerator also includes a connecting rod that extends in the vertical direction and is fixedly connected to the first housing, the second housing, the third housing, and the fourth housing, respectively.

9. The chiller of claim 1, wherein, The generator is located on the upper side of the absorber.

10. The chiller of claim 1, wherein, The refrigerator also includes a vacuum pump, which is connected to the first cavity and the fourth cavity via pipes.

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