A cascade refrigeration system

Abstract

The application provides a cascade refrigeration system and belongs to the technical field of refrigeration cycles. The application solves the problem that energy circulation of the existing refrigeration system is not reasonably utilized. The cascade refrigeration system comprises a compressor, a condenser, a gas-liquid separator and an evaporator. The gas outlet of the compressor is connected with the gas inlet of the condenser. The liquid outlet of the condenser is connected with the liquid inlet of the gas-liquid separator. The gas-liquid separator comprises a shell and a regenerator arranged in the shell. The regenerator comprises a plurality of parallel heat exchange pipes. The liquid inlets of the regenerator and the evaporator are connected with the liquid outlet of the shell. The gas outlets of the regenerator and the evaporator are connected with the gas inlet of the shell. The gas outlet of the shell is connected with the gas inlet of the compressor. A plurality of upper baffle plates and lower baffle plates are further connected in the shell. The cascade refrigeration system improves the energy utilization efficiency and the convenience of use of the cascade refrigeration system.

Description

Technical Field

[0001] This invention belongs to the field of refrigeration cycle technology and relates to a cascade refrigeration system. Background Technology

[0002] Industrial refrigeration systems, such as cold storage, food processing freezing lines, chemical process cooling, and cold chain logistics centers, all use refrigeration systems for cooling. The efficiency and safety of the refrigeration cycle mainly depend on the liquid supply status on the evaporator side and the gas status on the compressor suction side. To improve the cooling effect, existing systems use cascade refrigeration systems, which typically employ heat exchangers to achieve heat circulation and conversion, thereby improving heat conversion efficiency.

[0003] For example, Chinese patent application [Patent Application No.: 201910746331.2] discloses a novel explosion-proof heat exchanger, including a shell-and-tube heat exchanger. The shell-and-tube heat exchanger is provided with a heat exchanger shell. A cold fluid inlet is connected to one side of the upper end of the heat exchanger shell, and a cold fluid outlet is connected to the other side of the upper end of the heat exchanger shell. A hot fluid outlet is connected to one end of the shell-and-tube heat exchanger. Heat exchange tubes are installed inside the shell-and-tube heat exchanger. Baffles are also installed inside the shell-and-tube heat exchanger. An automatic drainer is installed on one side of the shell-and-tube heat exchanger. The automatic drainer and the shell-and-tube heat exchanger are connected by a connecting pipe. The connecting pipe is also connected to a coil heat exchanger. The coil heat exchanger includes a hot fluid inlet and a coil. The hot fluid inlet is located at one end of the coil.

[0004] In the above structure, cold fluid enters the heat exchanger shell through the cold fluid inlet and is first cooled by the coil. The hot fluid that needs to be cooled enters through the hot fluid inlet and is cooled by the coil. After cooling, the condensate is discharged by the automatic drainer under its own gravity. The gas enters the heat exchanger shell and is cooled by the cold fluid in the heat exchange tubes. The flow direction of the gas is changed by the baffle plate to increase the contact time between the gas and the heat exchange tubes and improve the cooling effect of the gas. The cooled gas flows out through the hot fluid outlet, achieving the separation and rapid cooling of the gas-liquid mixture. However, the automatic drainer is still needed to separate the gas-liquid mixture in the whole process, which makes the overall structure of the shell and tube heat exchanger complex. Furthermore, the need for secondary cooling of the gas-liquid mixture by the coil and heat exchange tubes results in the overall energy cycle not being used efficiently and the energy exchange efficiency being low. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing a cascade refrigeration system. The technical problem this invention aims to solve is: how to address the issue of inefficient energy recycling in existing refrigeration systems.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A cascade refrigeration system includes a compressor, a condenser, a gas-liquid separator, and an evaporator. The outlet of the compressor is connected to the inlet of the condenser, and the outlet of the condenser is connected to the inlet of the gas-liquid separator. The gas-liquid separator includes a shell and a regenerator disposed within the shell. The regenerator includes multiple parallel heat exchange tubes. The inlets of the regenerator and the evaporator are both connected to the outlet of the shell. The outlets of the regenerator and the evaporator are both connected to the inlet of the shell. The outlet of the shell is connected to the inlet of the compressor. Multiple upper and lower baffles are also connected within the shell. The upper and lower baffles are distributed along the length of the heat exchange tubes and are staggered vertically.

[0008] After the refrigerant gas is compressed into a high-temperature, high-pressure superheated gas in the compressor, it enters the condenser. In the condenser, heat exchange occurs through the cooling medium, which carries away the heat, condensing the superheated gas into a room-temperature, high-pressure saturated refrigerant liquid. This liquid then enters the gas-liquid separator from the condenser's outlet. The low-temperature, low-pressure liquid refrigerant flowing out of the gas-liquid separator splits into two paths. The first path connects most of the low-temperature, low-pressure liquid refrigerant to the evaporator's inlet, allowing the evaporator to exchange heat with the external high-temperature medium, thus cooling it and achieving a refrigeration effect. After refrigeration, the low-temperature, low-pressure liquid refrigerant evaporates into a low-temperature, low-pressure gaseous refrigerant (usually containing a mist of liquid refrigerant) and enters the outer shell of the gas-liquid separator. There, it mixes with the low-temperature, low-pressure liquid refrigerant from the condenser (after throttling), completing the heat exchange. The liquid refrigerant cools down and transforms into a saturated or slightly superheated gaseous refrigerant, which is then drawn into the compressor and enters the next refrigeration compression cycle. Alternatively, the low-temperature, low-pressure liquid refrigerant inside the gas-liquid separator shell is throttled and enters the inlet of the regenerator, transforming into an even lower-temperature, low-pressure liquid refrigerant. This liquid refrigerant exchanges heat with the slightly warmer low-temperature, low-pressure liquid refrigerant and low-temperature, low-pressure gaseous refrigerant outside the heat exchange tubes, causing some of the cooler liquid refrigerant inside the tubes to evaporate. This evaporates from the outlet of the heat exchange tubes and then enters the shell through the inlet. Inside the shell, after complete mixing, heat exchange, and gas-liquid separation, it transforms into a saturated or slightly superheated gaseous refrigerant, which is then drawn into the compressor and enters the next refrigeration compression cycle.

[0009] In the above structure, a portion of the low-temperature, low-pressure liquid refrigerant flows into the inlet of the regenerator through the second path, maintaining a low temperature in the heat exchange tubes. Meanwhile, the low-temperature, low-pressure vaporized refrigerant enters the outer shell through the evaporator, where energy exchange occurs. To achieve rapid gas-liquid separation during this energy exchange, upper and lower baffles are installed. Guided by these baffles, the low-temperature, low-pressure vaporized refrigerant flows radially through the heat exchange tubes of the regenerator repeatedly, resulting in rapid gas-liquid separation. The refrigerant continuously impacts, changes its flow velocity and direction between the heat exchange tubes, achieving gas-liquid separation. This forces the low-temperature, low-pressure gaseous refrigerant to pass through the liquid inside the shell, and also extends the gas flow path, making the gas-liquid separation more thorough. Therefore, this application achieves energy circulation and stable gas-liquid separation by adding a branch and using upper and lower baffles, thereby improving the energy utilization efficiency of the cascade refrigeration system and enhancing its ease of use.

[0010] In the aforementioned cascade refrigeration system, the cascade refrigeration system further includes a throttling valve, and the liquid outlet of the outer casing is connected to the liquid inlet of the regenerator through the throttling valve.

[0011] The throttle valve further lowers the temperature of the low-temperature, low-pressure liquid refrigerant flowing into the regenerator in the second path, enabling gas-liquid separation of the low-temperature, low-pressure gaseous refrigerant entering the casing. By further utilizing the existing refrigerant, energy exchange and gas-liquid separation can be achieved, improving ease of use.

[0012] In the aforementioned cascade refrigeration system, the regenerator further includes a front support plate and a rear support plate fixedly connected to the outer shell. The two ends of the heat exchange tube are respectively inserted into the front support plate and the rear support plate. The front support plate is close to the air outlet of the outer shell, and an air passage is formed between the upper side of the front support plate and the inner wall of the outer shell. The rear support plate is close to the air inlet of the outer shell, and the upper side of the rear support plate is attached to and sealed to the inner wall of the outer shell.

[0013] By forming an air passage between the front support plate and the inner wall of the outer casing near the air outlet, the gas after gas-liquid separation can be quickly discharged from the air outlet. The upper side of the rear support plate is sealed and fixed to the outer casing. The rear support plate is close to the air inlet of the outer casing, so the low-temperature and low-pressure gaseous refrigerant entering the outer casing can flow downward along the rear support plate and pass through the low-temperature and low-pressure liquid refrigerant located at the bottom of the outer casing. This increases the path length of the low-temperature and low-pressure gaseous refrigerant inside the outer casing, thereby making the gas-liquid separation more thorough.

[0014] In the aforementioned cascade refrigeration system, the vertical distance between the lower side of the rear support plate and the inner bottom wall of the outer casing is greater than the vertical distance between the lower side of the lower baffle plate and the inner bottom wall of the outer casing.

[0015] This structure allows for the rapid entry of low-temperature, low-pressure gaseous refrigerant into the outer casing, where it then passes through the low-temperature, low-pressure liquid refrigerant under the action of the lower baffle. This design enables the lower baffle to achieve a better flow-deflecting effect, thereby making the gas-liquid separation more stable and improving the cooling effect of the cascade refrigeration system.

[0016] In the aforementioned cascade refrigeration system, the regenerator further includes a support cylinder connecting the front support plate and the rear support plate. The support cylinder has an opening between two adjacent upper baffles, between the upper baffle and the front support plate, and between the upper baffle and the rear support plate. The support cylinder also has an opening between two adjacent lower baffles, between the lower baffle and the front support plate, and between the lower baffle and the rear support plate.

[0017] By setting opening one and opening two, the opening area should be as large as possible without affecting the supporting function of the support cylinder, thereby increasing the contact area between the low-temperature and low-pressure gaseous refrigerant and the heat exchange tube, ensuring more stable energy exchange when the low-temperature and low-pressure gaseous refrigerant flows, and without affecting the structural strength of the support cylinder.

[0018] Specifically, both opening one and opening two are bow-shaped notches.

[0019] The upper and lower baffles not only enhance airflow turbulence and heat transfer, but also enhance gas-liquid separation when combined with heat exchange tubes.

[0020] In the aforementioned cascade refrigeration system, a hemispherical front cover is fixedly connected to the front support plate, and a hemispherical rear cover is fixedly connected to the rear support plate. An inlet pipe and an outlet pipe with their ends extending out of the outer shell are connected to the front cover. A partition is provided inside the front cover to separate the space formed by the cover and the front support plate. The inlet pipe and the outlet pipe are located on both sides of the partition.

[0021] A hemispherical front cover is fixedly installed on the front support plate, and a hemispherical rear cover is fixedly installed on the rear support plate. This ensures that the liquid entering through the inlet pipe and the gas flowing out through the outlet pipe will not interfere with each other, further improving the stability of gas-liquid separation and thus enhancing the stability of the cascade refrigeration system.

[0022] In the aforementioned cascade refrigeration system, the cascade refrigeration system further includes a second throttling valve, and the condenser is connected to the liquid inlet of the outer casing through the second throttling valve.

[0023] The second throttle valve further cools the room-temperature, high-pressure saturated refrigerant liquid flowing out of the condenser, resulting in a lower liquid temperature entering the gas-liquid separator. This ensures that the refrigerant liquid with a lower temperature is supplied to the evaporator, thus improving the cooling effect of the cascade refrigeration system.

[0024] In the aforementioned cascade refrigeration system, the cascade refrigeration system further includes a constant pressure valve, and the outlet of the regenerator is connected to the inlet of the outer casing through the constant pressure valve.

[0025] The low-temperature, low-pressure gaseous refrigerant of the regenerator is connected to the gas inlet of the shell through a constant pressure valve. The constant pressure valve can stabilize the gas pressure inside the shell, ensuring that the low-temperature, low-pressure gaseous refrigerant flowing out of the regenerator enters the shell at a constant pressure, maintaining the internal pressure of the system, avoiding pressure fluctuations from affecting the gas-liquid separation effect, and improving stability.

[0026] In the aforementioned cascade refrigeration system, a liquid outlet valve and a liquid level sensor are provided at the bottom of the outer casing. After the liquid level sensor detects a change in the liquid level inside the casing, it transmits a signal to an external controller, which then controls the opening degree of the liquid outlet valve.

[0027] By combining the liquid outlet valve and the liquid level sensor, the opening of the liquid outlet valve can be adjusted according to the liquid level. When the gas-liquid mixture flows, it is necessary to ensure that after entering the shell from the air inlet, it directly exchanges heat with the heat exchange tube under the guidance of the rear support plate, and then flows into the low-temperature and low-pressure refrigerant liquid in the shell under the guidance of the lower baffle plate, thereby improving the overall cooling stability.

[0028] The distance between the lower side of the lower baffle and the bottom wall of the outer shell is H1, the distance between the lower side of the rear support plate and the bottom wall of the outer shell is H2, and the liquid level inside the outer shell is H3. When the cascade refrigeration system is working, it is necessary to satisfy H2 > H3 > H1 so that the liquid level does not submerge all the heat exchange tubes. Maintaining this level can achieve a better cooling effect.

[0029] In the aforementioned cascade refrigeration system, the cascade refrigeration system further includes an auxiliary compressor, an auxiliary condenser, and a liquid receiver. The liquid receiver includes a block-shaped auxiliary outer shell and a subcooler disposed at the bottom of the auxiliary outer shell. The subcooler includes a tube shell and multiple auxiliary heat exchange tubes disposed within the tube shell. The outlet of the auxiliary compressor is connected to the auxiliary condenser. The outlet of the auxiliary condenser is connected to the inlet of the auxiliary outer shell. The outlet of the auxiliary outer shell is connected to the inlet of the condenser. The outlet of the condenser is connected to the inlet of the tube shell. The outlet of the tube shell is connected to the inlet of the auxiliary compressor.

[0030] When a compressor, evaporator, gas-liquid separator, and condenser are used for refrigeration, the compressor, evaporator, gas-liquid separator, and condenser are used for low-temperature refrigeration. The auxiliary compressor, auxiliary condenser, and receiver must be turned on, and the auxiliary compressor, auxiliary condenser, and receiver are used for high-temperature refrigeration. The cooling capacity of the high-temperature stage removes the condensing heat of the low-temperature stage in the condenser, making the refrigeration effect of the low-temperature stage better.

[0031] Compared with existing technologies, this cascade cooling system has the following advantages:

[0032] 1. A portion of the low-temperature, low-pressure liquid refrigerant flows into the inlet of the regenerator, maintaining a low temperature in the heat exchange tubes. The refrigerant then passes through the evaporator and enters the low-temperature, low-pressure vaporized refrigerant inside the casing. Energy exchange occurs between the two. To achieve rapid gas-liquid separation during this energy exchange, upper and lower baffles are installed. These baffles force the low-temperature, low-pressure vaporized refrigerant to pass through the liquid inside the casing, extending the gas flow path and making gas-liquid separation more thorough. Therefore, this application achieves energy circulation and stable gas-liquid separation by adding a branch path and using upper and lower baffles, thereby improving the energy utilization efficiency and ease of use of the cascade refrigeration system.

[0033] 2. By setting opening one and opening two, the opening area should be as large as possible without affecting the supporting function of the support cylinder, thereby increasing the contact area between the low-temperature and low-pressure gaseous refrigerant and the heat exchange tube, ensuring more stable energy exchange when the low-temperature and low-pressure gaseous refrigerant flows, and without affecting the structural strength of the support cylinder. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of the present invention.

[0035] Figure 2 This is a partial cross-sectional view of the gas-liquid separator in this invention.

[0036] Figure 3 This is a partial structural schematic diagram of the gas-liquid separator in this invention.

[0037] Figure 4 This is a schematic diagram of the support cylinder in this invention.

[0038] Figure 5 This is a schematic diagram of the subcooler in this invention.

[0039] In the diagram, 1. Compressor; 2. Oil separator; 3. Condenser; 4. Gas-liquid separator; 41. Outer shell; 42. Regenerator; 42a. Heat exchange tube; 42b. Front support plate; 42c. Rear support plate; 43. Upper baffle; 43a. Opening 1; 44. Lower baffle; 44a. Opening 2; 45. Gas outlet; 46. Front cover; 46a. Partition plate; 47. Rear cover; 48. Liquid inlet pipe; 49. Gas outlet pipe; 4a. Support cylinder; 5. Evaporator; 6. Throttling valve 1; 7. Throttling valve 2; 8. Auxiliary compressor; 9. Auxiliary oil separator; 10. Auxiliary condenser; 1a. Liquid receiver; 1a1. Auxiliary outer shell; 1a2. Auxiliary heat exchange tube; 1a3. Subcooler; 1a4. Tube shell; 1b. Constant pressure valve; 1c. Liquid outlet valve; 1d. Liquid level sensor. Detailed Implementation

[0040] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0041] like Figure 1 As shown, this cascade refrigeration system includes a compressor 1, an oil separator 2, a condenser 3, a gas-liquid separator 4, and an evaporator 5. The outlet of the compressor 1 is connected to the inlet of the oil separator 2, the outlet of the oil separator 2 is connected to the inlet of the condenser 3, and the liquid outlet of the condenser 3 is connected to the liquid inlet of the gas-liquid separator 4.

[0042] Specifically, such as Figure 1-5As shown, the gas-liquid separator 4 includes a housing 41 and a regenerator 42 disposed within the housing 41. The regenerator 42 includes multiple parallel heat exchange tubes 42a. The liquid inlet of the regenerator 42 and the liquid inlet of the evaporator 5 are both connected to the liquid outlet of the housing 41. The gas outlet of the regenerator 42 and the gas outlet of the evaporator 5 are both connected to the gas inlet of the housing 41. The gas outlet of the housing 41 is connected to the gas inlet of the compressor 1. Multiple upper baffles 43 and lower baffles 44 are also connected inside the housing 41. The upper baffles 43 and lower baffles 44 are distributed along the length of the heat exchange tubes 42a and are staggered vertically. This cascade refrigeration system also includes a first throttling valve 6 and a second throttling valve 7. The liquid outlet of the housing 41 and the liquid inlet of the regenerator 42 are connected through the first throttling valve 6, and the condenser 3 is connected to the housing 41 through the second throttling valve 7. The cascade refrigeration system also includes an auxiliary compressor 8, an auxiliary oil separator 9, an auxiliary condenser 10, and a liquid receiver 1a. The liquid receiver 1a includes a block-shaped auxiliary housing 1a1 and a subcooler 1a3 disposed at the bottom of the auxiliary housing 1a1. The subcooler 1a3 includes a tube shell 1a4 and multiple auxiliary heat exchange tubes 1a2 disposed inside the tube shell 1a4. The outlet of the auxiliary compressor 8 is connected to the inlet of the auxiliary oil separator 9. The outlet of the auxiliary oil separator 9 is connected to the inlet of the auxiliary condenser 10. The outlet of the auxiliary condenser 10 is connected to the inlet of the auxiliary housing 1a1. The outlet of the auxiliary housing 1a1 is connected to the inlet of the condenser 3. The outlet of the condenser 3 is connected to the inlet of the tube shell 1a4. The outlet of the tube shell 1a4 is connected to the inlet of the auxiliary compressor 8.

[0043] After the refrigerant gas is compressed into a high-temperature, high-pressure superheated gas in the auxiliary compressor 8, it carries atomized lubricating oil into the auxiliary oil separator 9. The atomized lubricating oil gathers or condenses in the auxiliary oil separator 9 and is retained there. The high-temperature, high-pressure superheated gas then enters the auxiliary condenser 10. Heat exchange occurs in the auxiliary condenser 10, where the heat of the refrigerant is carried away by the coolant and condensed into a room-temperature, high-pressure saturated refrigerant liquid. This liquid enters the receiver 1a from the outlet of the auxiliary condenser 10. The room-temperature, high-pressure saturated refrigerant liquid submerges the auxiliary heat exchange tubes 1a2 of the receiver 1a, making complete contact with the tube walls. It continues to exchange heat with the low-temperature, low-pressure refrigerant gas passing through the auxiliary heat exchange tubes 1a2, further reducing the temperature of the room-temperature, high-pressure saturated refrigerant liquid, cooling it into a room-temperature, high-pressure subcooled refrigerant liquid. This subcooled refrigerant liquid is then throttled, due to… The throttling effect transforms the refrigerant into a low-temperature, low-pressure liquid, which enters the outer shell 41 of the condenser 3. After exchanging heat with another high-temperature, high-pressure gaseous refrigerant, the low-temperature, low-pressure liquid refrigerant evaporates into a low-temperature, low-pressure gaseous refrigerant. Usually, it carries a mist-like liquid refrigerant into the auxiliary heat exchange tube 1a2 of the receiver 1a. There, it exchanges heat with the ambient-temperature, high-pressure saturated refrigerant liquid from the auxiliary condenser 10 outside the auxiliary heat exchange tube 1a2. The low-temperature, low-pressure refrigerant in the auxiliary heat exchange tube 1a2 completely evaporates and transforms into a saturated or slightly superheated gaseous refrigerant, which is then drawn away by the auxiliary compressor 8 and enters the next refrigeration compression cycle.

[0044] Another type of refrigerant gas is compressed into a high-temperature, high-pressure superheated gas in compressor 1, carrying mist-like lubricating oil into oil separator 2. The mist-like lubricating oil accumulates or condenses in oil separator 2 and is retained there. The high-temperature, high-pressure superheated gas then enters the shell side of condenser 3. In condenser 3, heat exchange occurs between the gas and a low-temperature, low-pressure liquid refrigerant within the condenser tubes. The heat from the other high-temperature, high-pressure refrigerant is carried away by the low-temperature, low-pressure liquid refrigerant, condensing into a room-temperature, high-pressure saturated refrigerant liquid. As this liquid flows from the outlet of condenser 3 through throttling valve 7, the sudden change in flow area causes the room-temperature, high-pressure subcooled refrigerant liquid to transform into a low-temperature, low-pressure refrigerant liquid due to the throttling effect. This liquid then enters gas-liquid separator 4. The other refrigerant, after being throttled by throttling valve 7, transforms into a low-temperature, low-pressure liquid refrigerant, carrying flash gas.

[0045] The outlet of the gas-liquid separator 4 is divided into two branches. In the first branch, most of the low-temperature, low-pressure liquid refrigerant is connected to the inlet of the evaporator 5. The evaporator 5 achieves heat exchange with the external high-temperature medium, thereby cooling the external high-temperature medium and achieving a refrigeration effect. After refrigeration, the low-temperature, low-pressure liquid refrigerant evaporates into a low-temperature, low-pressure gaseous refrigerant, which usually carries mist-like liquid refrigerant. This vapor then enters the outer shell 41 of the gas-liquid separator 4 and mixes with the low-temperature, low-pressure liquid refrigerant from the condenser 3 after throttling, thus completing the heat exchange. The liquid refrigerant temperature decreases, transforming into a saturated or slightly superheated gaseous refrigerant which is drawn away by compressor 1 and enters the next refrigeration compression cycle. Alternatively, the low-temperature, low-pressure liquid refrigerant inside the outer shell 41 of the gas-liquid separator 4 enters the inlet of the regenerator 42 after throttling, transforming into an even lower-temperature, low-pressure liquid refrigerant. This liquid refrigerant exchanges heat with the slightly higher-temperature liquid and gaseous refrigerant outside the heat exchange tube 42a through the tube wall, causing some of the lower-temperature liquid refrigerant inside the tubes to evaporate and flow out from the outlet of the heat exchange tube 42a. After flowing out, it enters the outer shell 41 through the inlet of the shell, where it undergoes complete mixing, heat exchange, and gas-liquid separation. It then transforms into a saturated or slightly superheated gaseous refrigerant which is drawn away by compressor 1 and enters the next refrigeration compression cycle.

[0046] In the above structure, a portion of the low-temperature, low-pressure liquid refrigerant flows into the inlet of the regenerator 42 through the second path, maintaining a low temperature in the heat exchange tube 42a. The refrigerant then passes through the evaporator 5 and enters the low-temperature, low-pressure vaporized refrigerant inside the outer shell 41. Energy exchange occurs between the two. To achieve rapid gas-liquid separation during this energy exchange, an upper baffle 43 and a lower baffle 44 are installed. This forces the low-temperature, low-pressure vaporized refrigerant to pass through the liquid inside the outer shell 41, extending the gas flow path and making gas-liquid separation more thorough. Therefore, this application achieves energy circulation and stable gas-liquid separation by adding a branch path and using the upper baffle 43 and lower baffle 44, thereby improving the energy utilization efficiency of the cascade refrigeration system and enhancing its ease of use.

[0047] like Figure 2 and Figure 3As shown, the regenerator 42 also includes a front support plate 42b and a rear support plate 42c fixedly connected to the outer shell 41. The two ends of the heat exchange tube 42a are respectively inserted into the front support plate 42b and the rear support plate 42c. The front support plate 42b is close to the air outlet of the outer shell 41. An air passage 45 is formed between the upper side of the front support plate 42b and the inner wall of the outer shell 41. The rear support plate 42c is close to the air inlet of the outer shell 41. The upper side of the rear support plate 42c is attached to and sealed to the inner wall of the outer shell 41. The vertical distance between the lower side of the rear support plate 42c and the inner bottom wall of the outer shell 41 is greater than the vertical distance between the lower side of the lower baffle 44 and the inner bottom wall of the outer shell 41.

[0048] like Figure 1-4 As shown, the regenerator 42 also includes a support cylinder 4a connecting the front support plate 42b and the rear support plate 42c. The support cylinder 4a has openings 43a between two adjacent upper baffles 43, between the upper baffle 43 and the front support plate 42b, and between the upper baffle 43 and the rear support plate 42c. The support cylinder 4a also has openings 44a between two adjacent lower baffles 44, between the lower baffle 44 and the front support plate 42b, and between the lower baffle 44 and the rear support plate 42c. The front support plate 42b... A hemispherical front cover 46 is fixedly connected to the front support plate 42b, and a hemispherical rear cover 47 is fixedly connected to the rear support plate 42c. An inlet pipe 48 and an outlet pipe 49 with their ends extending out of the outer shell 41 are connected to the front cover 46. A partition plate 46a is provided inside the front cover 46 to separate the space formed by the front cover 46 and the front support plate 42b. The inlet pipe 48 and the outlet pipe 49 are located on both sides of the partition plate 46a. This cascade refrigeration system also includes a constant pressure valve 1b. The outlet of the regenerator 42 is connected to the inlet of the outer shell 41 through the constant pressure valve 1b.

[0049] The upper baffle 43, lower baffle 44, front support plate 42b and rear support plate 42c of the above structure divide the regenerator 42 into multiple regions that run from end to end at the heat exchange tube 42a.

[0050] like Figure 1 and Figure 2 As shown, a liquid outlet valve 1c and a liquid level sensor 1d are provided at the bottom of the housing 41. After the liquid level sensor 1d detects the change in liquid level inside the housing 41, it transmits the signal to an external controller, which controls the opening degree of the liquid outlet valve 1c.

[0051] A manhole is provided axially at one end of the outer casing 41. The cross-sectional projection of the manhole coincides with that of the heat exchange tube 42a, which facilitates maintenance personnel to enter the outer casing 41 to perform maintenance on the heat exchange tube 42a.

[0052] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A cascade refrigeration system, comprising a compressor (1), a condenser (3), a gas-liquid separator (4), and an evaporator (5), wherein the outlet of the compressor (1) is connected to the inlet of the condenser (3), and the liquid outlet of the condenser (3) is connected to the liquid inlet of the gas-liquid separator (4), characterized in that, The gas-liquid separator (4) includes a shell (41) and a regenerator (42) disposed inside the shell (41). The regenerator (42) includes multiple parallel heat exchange tubes (42a). The liquid inlet of the regenerator (42) and the liquid inlet of the evaporator (5) are both connected to the liquid outlet of the shell (41). The gas outlet of the regenerator (42) and the gas outlet of the evaporator (5) are both connected to the gas inlet of the shell (41). The gas outlet of the shell (41) is connected to the gas inlet of the compressor (1). Multiple upper baffles (43) and lower baffles (44) are also connected inside the shell (41). The upper baffles (43) and lower baffles (44) are distributed along the length of the heat exchange tubes (42a) and are staggered vertically.

2. The cascade cooling system according to claim 1, characterized in that, The cascade refrigeration system also includes a throttle valve (6), and the liquid outlet of the outer shell (41) is connected to the liquid inlet of the regenerator (42) through the throttle valve (6).

3. The cascade refrigeration system according to claim 1 or 2, characterized in that, The regenerator (42) also includes a front support plate (42b) and a rear support plate (42c) fixedly connected to the outer shell (41). The two ends of the heat exchange tube (42a) are respectively inserted into the front support plate (42b) and the rear support plate (42c). The front support plate (42b) is close to the air outlet of the outer shell (41). An air passage (45) is formed between the upper side of the front support plate (42b) and the inner wall of the outer shell (41). The rear support plate (42c) is close to the air inlet of the outer shell (41). The upper side of the rear support plate (42c) is attached to and sealed to the inner wall of the outer shell (41).

4. The cascade cooling system according to claim 3, characterized in that, The vertical distance between the lower side of the rear support plate (42c) and the inner bottom wall of the outer shell (41) is greater than the vertical distance between the lower side of the lower baffle plate (44) and the inner bottom wall of the outer shell (41).

5. The cascade cooling system according to claim 3, characterized in that, The regenerator (42) further includes a support cylinder (4a) connecting the front support plate (42b) and the rear support plate (42c). The support cylinder (4a) has an opening (43a) between two adjacent upper baffles (43), between the upper baffle (43) and the front support plate (42b), and between the upper baffle (43) and the rear support plate (42c). The support cylinder (4a) also has an opening (44a) between two adjacent lower baffles (44), between the lower baffle (44) and the front support plate (42b), and between the lower baffle (44) and the rear support plate (42c).

6. The cascade cooling system according to claim 5, characterized in that, A hemispherical front cover (46) is fixedly connected to the front support plate (42b), and a hemispherical rear cover (47) is fixedly connected to the rear support plate (42c). An inlet pipe (48) and an outlet pipe (49) with their ends extending out of the outer shell (41) are connected to the front cover (46). A partition (46a) is provided inside the front cover (46) to separate the space formed by the front cover (46) and the front support plate (42b). The inlet pipe (48) and the outlet pipe (49) are located on both sides of the partition (46a).

7. The cascade refrigeration system according to claim 1 or 2, characterized in that, The cascade refrigeration system also includes a second throttle valve (7), and the condenser (3) is connected to the liquid inlet of the outer casing (41) through the second throttle valve (7).

8. The cascade refrigeration system according to claim 1 or 2, characterized in that, The cascade refrigeration system also includes a constant pressure valve (1b), and the outlet of the regenerator (42) is connected to the inlet of the outer casing (41) through the constant pressure valve (1b).

9. The cascade refrigeration system according to claim 1 or 2, characterized in that, The bottom of the housing (41) is provided with a liquid outlet valve (1c) and a liquid level sensor (1d). After the liquid level sensor (1d) detects the change in liquid level inside the housing (41), it transmits the signal to an external controller, which controls the opening degree of the liquid outlet valve (1c).

10. The cascade refrigeration system according to claim 1 or 2, characterized in that, This cascade refrigeration system also includes an auxiliary compressor (8), an auxiliary condenser (10), and a liquid receiver (1a). The liquid receiver (1a) includes a block-shaped auxiliary shell (1a1) and a subcooler (1a3) disposed at the bottom of the auxiliary shell (1a1). The subcooler (1a3) includes a tube shell (1a4) and multiple auxiliary heat exchange tubes (1a2) disposed inside the tube shell (1a4). The outlet of the auxiliary compressor (8) is connected to the auxiliary condenser (10). The outlet of the auxiliary condenser (10) is connected to the inlet of the auxiliary shell (1a1). The outlet of the auxiliary shell (1a1) is connected to the inlet of the condenser (3). The outlet of the condenser (3) is connected to the inlet of the tube shell (1a4). The outlet of the tube shell (1a4) is connected to the inlet of the auxiliary compressor (8).

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