An ultra-low temperature refrigeration system

Abstract

This invention discloses an ultra-low temperature refrigeration system employing a dual-compressor cascade refrigeration method. It includes a condenser module, a primary compression system sharing a heat exchanger, and a secondary compression system. The condenser module comprises a first pipe, a second pipe, and a third pipe. The inlet end of the first pipe is connected to the discharge end of the secondary compressor in the secondary compression system, and the outlet end of the first pipe is connected to the first inlet of the heat exchanger. The inlet end of the second pipe is connected to the discharge end of the primary compressor in the primary compression system, and the outlet end of the second pipe is connected to the inlet of the decondensation pipe in the primary compression system. The inlet end of the third pipe is connected to the outlet end of the decondensation pipe, and the outlet end of the third pipe is connected to the second inlet of the heat exchanger. This invention can effectively reduce the heat load inside the compressor compartment, which is beneficial for improving the cooling rate of the compressor compartment and enhancing refrigeration efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of refrigeration, and particularly relates to an ultralow-temperature refrigeration system. BACKGROUND

[0002] An ultralow-temperature cabinet is a kind of preservation cabinet that can reduce the temperature in the cabinet to below-80℃ and maintain the temperature in the cabinet, for example, to preserve medical products. Due to the large evaporation-condensation pressure difference and the limitations of the compressor, a single compressor is difficult to meet the requirements, and currently ultralow-temperature cabinets generally adopt a double-compressor cascade refrigeration mode. Among them, the first-stage refrigeration system makes the refrigerant reach about-40℃ to exchange heat with the evaporative condenser, and the second-stage refrigeration system makes the refrigerant reach below-80℃ to exchange heat with the inside of the ultralow-temperature cabinet on the basis of the first-stage system.

[0003] In the prior art, the refrigerant in the second-stage system is discharged from the compressor, enters the heat exchanger for heat exchange after passing through the oil separator; in the above process, the high-temperature refrigerant vapor discharged from the compressor directly enters the low-temperature oil separator, and due to the excessively high temperature of the vapor, the separation efficiency of the oil separator is low; and too much lubricating oil enters the subsequent heat exchange in the refrigeration cycle, reducing the heat exchange effect.

[0004] In addition, in the first-stage system of the prior art, the refrigerant is introduced from the inside of the compressor, first enters the dew removal pipe and then enters the condenser, which increases the energy consumption of the compressor, makes the thermal load in the compressor cabin large, and affects the refrigeration efficiency.

[0005] In the prior art, the first-stage system directly exchanges heat with the surrounding environment, i.e., discharges heat into the compressor cabin, which can cause the temperature in the compressor cabin to rise, the thermal load to be excessively large, and the refrigeration efficiency to be affected. In order to better dissipate heat, a fan is often used for heat dissipation in the prior art, but there is still the defect of low cooling speed. There is also a structure for dissipating heat by using water cooling in the prior art, for example, the composite ultralow-temperature refrigeration system disclosed in Chinese Patent Document CN 202011365087.4; however, the structure of this way is relatively complex. SUMMARY

[0006] The main purpose of the present application is to provide an ultralow-temperature refrigeration system that reduces the thermal load in the compressor cabin and improves the refrigeration efficiency.

[0007] In order to achieve the above main purpose, the present application provides an ultralow-temperature refrigeration system, which adopts a double-compressor cascade refrigeration mode and includes a first-stage compression system and a second-stage compression system that share a heat exchanger, wherein:

[0008] The condenser module includes a first pipeline, a second pipeline and a third pipeline.

[0009] The inlet end of the first pipeline is connected with the exhaust end of the second-stage compressor in the second-stage compression system, and the outlet end of the first pipeline is connected with the first inlet of the heat exchanger;

[0010] The inlet end of the second pipeline is connected with the exhaust end of the first-stage compressor in the first-stage compression system, and the outlet end of the second pipeline is connected with the inlet of the dehumidification pipe in the first-stage compression system;

[0011] The inlet end of the third pipeline is connected with the outlet end of the dehumidification pipe, and the outlet end of the third pipeline is connected with the second inlet of the heat exchanger.

[0012] As a specific embodiment of the present application, the condenser module comprises a shell, a fan and fins;

[0013] The first pipeline, the second pipeline and the third pipeline are installed on the shell;

[0014] The fan is arranged on the shell and located on the opposite side of the first pipeline, the second pipeline and the third pipeline;

[0015] The fins are installed on the first pipeline, the second pipeline and the third pipeline.

[0016] As a specific embodiment of the present application, the effective length of the first pipeline does not exceed the effective length of the second pipeline, and the effective length of the second pipeline does not exceed the effective length of the third pipeline.

[0017] As a specific embodiment of the present application, the first pipeline, the second pipeline and the third pipeline are arranged in a stack from top to bottom and are independent of each other.

[0018] As a specific embodiment of the present application, the first-stage compression system further comprises a first-stage drying filter, a first-stage capillary and a liquid reservoir; the first-stage compressor, the dehumidification pipe, the condenser module, the first-stage drying filter, the first-stage capillary, the heat exchanger and the liquid reservoir are sequentially communicated; the second-stage compression system further comprises an oil separator, a second-stage drying filter, a second-stage capillary and an evaporator; the second-stage compressor, the condenser module, the oil separator, the second-stage drying filter, the heat exchanger, the second-stage capillary and the evaporator are sequentially communicated.

[0019] As a specific embodiment of the present application, the outlet end of the first-stage capillary is connected with the first inlet of the heat exchanger, and the first outlet of the heat exchanger is connected with the inlet end of the liquid reservoir; the outlet end of the second-stage drying filter is connected with the second inlet of the heat exchanger, and the second outlet of the heat exchanger is connected with the inlet end of the second-stage capillary.

[0020] As a specific embodiment of the present application, the heat exchanger is a tubular heat exchanger.

[0021] In one specific embodiment of the present invention, the two-stage compression system further includes a regenerator; the first inlet of the regenerator is connected to the second outlet of the heat exchanger, and the first outlet of the regenerator is connected to the inlet end of the two-stage capillary tube; the second inlet of the regenerator is connected to the outlet end of the evaporator, and the second outlet of the regenerator is connected to the return gas end of the two-stage compressor.

[0022] In one specific embodiment of the present invention, the regenerator includes a shell and an intermediate conductive tube; the shell has a regenerating cavity, and the intermediate conductive tube is disposed inside the shell and isolated from the regenerating cavity; the two ends of the intermediate conductive tube respectively form a first inlet and a first outlet of the regenerator, and the second inlet and the second outlet of the regenerator are both connected to the regenerating cavity; or, the two ends of the intermediate conductive tube respectively form a second inlet and a second outlet of the regenerator, and the first inlet and the first outlet of the regenerator are both connected to the regenerating cavity.

[0023] In one specific embodiment of the present invention, the outer shell is cylindrical and the middle conductive tube is spiral.

[0024] The present invention has the following beneficial effects:

[0025] In the ultra-low temperature refrigeration system of the present invention, the condenser module adopts a three-inlet, three-outlet configuration. On the one hand, the first pipeline of the condenser module pre-cools the secondary compression system; on the other hand, the exhaust gas from the primary compressor first enters the second pipeline of the condenser module, then enters the decondenser pipe, then returns to the third pipeline of the condenser, and finally exits the condenser. The present invention can effectively reduce the heat load in the compressor compartment, which is conducive to improving the cooling rate of the compressor compartment and improving the refrigeration efficiency.

[0026] To more clearly illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Attached Figure Description

[0027] Figure 1 This is a structural diagram of the compressor compartment of the present invention;

[0028] Figure 2 This is a top view of the compressor compartment of the present invention;

[0029] Figure 3 This is a three-dimensional sectional view of the compressor compartment of the present invention;

[0030] Figure 4 This is a longitudinal sectional view of the compressor compartment of the present invention;

[0031] Figure 5 This is an exploded view of the condenser module of the present invention;

[0032] Figure 6 This is a partial structural diagram of the condenser module of the present invention;

[0033] Figure 7 This is a schematic diagram of the regenerator of the present invention;

[0034] Figure 8 This is a framework diagram of the cryogenic refrigeration system of the present invention;

[0035] Figure 9 This is a rendering of the cryogenic refrigeration system of the present invention;

[0036] Figure 10 This is a comparison chart of the effects of traditional ultra-low temperature refrigeration systems. Detailed Implementation

[0037] Numerous specific details are set forth in the following description to provide a thorough understanding of the invention, but the invention can also be practiced with other variations thereof. Therefore, other possible implementations that can be learned by those skilled in the art based on the embodiments described herein are all within the scope of protection of this invention.

[0038] The cryogenic refrigeration equipment of this invention includes a housing, a compressor compartment structure 10, and a cryogenic refrigeration system 20; wherein, the housing defines a compartment for storing items, which is used to place items that need to be cryogenically refrigerated, such as biological pharmaceuticals.

[0039] The cryogenic refrigeration system 20 in this embodiment of the invention is used to cool the internal environment of the compartment; the cryogenic refrigeration system 20 adopts a dual-compressor cascade refrigeration method, including a primary compression system 21 and a secondary compression system 22; as shown Figure 8 As shown, the primary compression system 21 (high temperature stage) includes a primary compressor 211, a decondenser pipe 212, a condenser module 30, a primary dryer filter 213, a primary capillary tube 214, a heat exchanger 40, and a liquid receiver 215 connected in sequence; the secondary compression system 22 (low temperature stage) includes a secondary compressor 221, a condenser module 30, an oil separator 222, a secondary dryer filter 223, a heat exchanger 40, a secondary capillary tube 224, an evaporator 225, and a regenerator 50; wherein, the heat exchanger 40 is preferably a tubular heat exchanger to save installation space.

[0040] The condenser module 30 in this embodiment of the invention adopts a three-in-three-out configuration, such as... Figures 5-6 , Figure 8 As shown, the condenser module 30 includes a housing 31, a fan 32, fins 33, and a condenser tube 34. The condenser tube 34 is mounted on the housing 31, the fan 32 is located on the air outlet side of the housing 31, and the fins 33 are mounted on the condenser tube 34. The condenser tube 34 includes a first pipe 341, a second pipe 342, and a third pipe 343.

[0041] Specifically, such as Figure 5As shown, the first pipe 341, the second pipe 342 and the third pipe 343 are stacked from top to bottom and are independent of each other to form a compact structure.

[0042] Please continue reading. Figure 8 In the condenser module 30 of this embodiment of the invention, the inlet end of the first pipe 341 is connected to the exhaust end of the second-stage compressor 221 in the second-stage compression system 22, and the outlet end of the first pipe 341 is connected to the first inlet of the heat exchanger 40 to pre-cool the second-stage compression system 22; the inlet end of the second pipe 342 is connected to the exhaust end of the first-stage compressor 211 in the first-stage compression system 21, and the outlet end of the second pipe 342 is connected to the inlet of the decondensation pipe 212 in the first-stage compression system 21; the inlet end of the third pipe 343 is connected to the outlet end of the decondensation pipe 212, and the outlet end of the third pipe 343 is connected to the second inlet of the heat exchanger 40.

[0043] The arrangement of the exhaust from the first-stage compressor 211 into the second pipe 342 of the condenser module 30, then into the decondenser pipe 212, then back into the third pipe 343 of the condenser module 30, and finally out of the condenser module 30, can reduce the heat load in the compressor compartment and improve the cooling rate of the compressor compartment. If the exhaust from the first-stage compressor 211 directly enters the decondenser pipe 212, the temperature of the door frame will rise, increasing the heat load. Therefore, by using the second pipe 342 of the first-stage compressor 211 for pre-cooling, then into the decondenser pipe 212, and finally into the third pipe 343 of the condenser module 30, the heat load added by the decondenser pipe 212 can be reduced.

[0044] Furthermore, in this embodiment of the invention, the first pipe 341 precools the low-temperature refrigerant R170 to reduce the heat load on the evaporator 225, making it easier for R170 to be subcooled to reach the required low temperature. The first pipe 341, the second pipe 342, and the third pipe 343 are independent of each other. R170 refrigerant flows through the first pipe 341, while R290 refrigerant flows through the second pipe 342 and the third pipe 343 to adjust the heat load of the decondensation pipe 212 on the housing. The lengths of the second pipe 342 and the third pipe 343 can be adjusted while keeping the total length of the second pipe 342 and the third pipe 343 constant.

[0045] Specifically, the length of the second pipe 342 directly affects the temperature of the R290 refrigerant entering the condenser pipe 212, thereby affecting the heat load of the condenser pipe 212 on the housing. Therefore, it is preferable to comprehensively consider both the door frame condensation and heat load conditions when determining the length of the second pipe 342. Preferably, the effective length of the first pipe 341 does not exceed the effective length of the second pipe 342, and the effective length of the second pipe 342 does not exceed the effective length of the third pipe 343. This distribution method can meet the pre-cooling requirements of the first pipe 341 for the secondary compression system 22, and also helps to reduce the heat load in the compressor compartment.

[0046] like Figures 1-4 As shown, the compressor compartment structure 10 of this embodiment of the invention has a bottom wall 11 and a front side wall 12 and a rear side wall 13 located on opposite sides of the bottom wall 11; the condenser module 30 is disposed on the bottom wall 11 and adjacent to the front side wall 12, and the front side wall 12 is provided with an air inlet 121, and the air inlet side of the condenser module 30 is connected to the air inlet 121; wherein, the area of ​​the front side wall 12 except for the air inlet 121 adopts a closed structure to isolate the hot and cold airflows from each other, so as to prevent the condensation heat in the compressor compartment from leaking out from the front side wall 12 and directly entering the air inlet side of the condenser module 30, thereby reducing the efficiency of the condenser module 30.

[0047] In an optional embodiment of the present invention, the air inlet 121 of the front sidewall 12 can be configured as a flared shape so that external cold air can be introduced into the condenser module 30 for heat dissipation.

[0048] In this embodiment of the invention, the bottom wall 11 is square, and the compressor compartment structure 10 also has a left side wall 14 and a right side wall 15 on the other opposite sides of the bottom wall 11. The left side wall 14, the right side wall 15 and the rear side wall 13 are all provided with air outlet grilles to expel the hot air in the compressor compartment as quickly as possible.

[0049] Please continue reading. Figure 2 The primary compressor 211 and the secondary compressor 221 are arranged side-by-side on the bottom wall 11 and located behind the condenser module 30. To prevent the hot airflow from the outlet side of the condenser module 30 from affecting the bottom of the compressor, the bottom wall 11 is provided with heat dissipation holes 111 and a baffle 112 located at the heat dissipation holes 111. The baffle 112 is located between the condenser module 30 and the primary compressor 211 and the secondary compressor 221. In the height direction, the top edge of the baffle 112 is set to not exceed the middle of the primary compressor 211 and the secondary compressor 221, so as to thermally insulate the area with a lower temperature at the bottom of the compressor. Correspondingly, the top of the compressor has a higher temperature, and the airflow formed by the fan in the condenser module 30 can also flow in the top area of ​​the compressor to remove the heat from the top of the compressor.

[0050] In this embodiment of the invention, the air outlet side of the condenser module 30 is preferably provided with an air guide duct 35, and the cooling fan 32 is disposed inside the air guide duct 35 to accelerate the gas flow and form a directional flow that flows towards the compressor at a faster speed, so as to quickly dissipate the heat from the compressor.

[0051] Furthermore, the baffle 112 is an inclined plate to provide a guide portion that is inclined toward the condenser module 30. The guide portion is used to prevent the hot airflow on the outlet side of the condenser module 30 from blowing directly toward the bottom of the primary compressor 211 and the secondary compressor 221, and to guide the hot airflow on the outlet side of the condenser module 30 to be discharged downward from the heat dissipation hole 111.

[0052] In this embodiment of the invention, the top edge of the baffle 112 is located at 1 / 5 to 1 / 3 of the overall height of the primary compressor 211 and the secondary compressor 221; for example Figure 4 As shown, the top edge of the baffle 112 is located, for example, at 1 / 4 of the overall height of the primary compressor 211 and the secondary compressor 221. The angle between the guide portion and the bottom wall 11 is 30°-70°, specifically, for example, 45°, so as to guide the hot airflow towards the heat dissipation hole 111 and downwards while preventing the hot airflow from the outlet side of the condenser module 30 from blowing directly towards the compressor.

[0053] In this embodiment of the invention, the heat dissipation hole 111 can be open to reduce exhaust obstruction and allow gas to be discharged quickly; in other embodiments, the heat dissipation hole 111 can also be mesh-shaped.

[0054] The compressor compartment structure 10 in this embodiment of the invention isolates the air inlet side and air outlet side of the condenser module 30, which is beneficial to improving the efficiency of the condenser module 30; at the same time, the heat dissipation holes 111 and baffles 112 are used to quickly dissipate the condensation heat, which is beneficial to reducing the impact of the condensation heat on the compressor and other components in the compartment.

[0055] like Figures 3-4 As shown, in this embodiment of the invention, the oil separator 222 is disposed on the bottom wall 11, wherein the top of the oil separator 222 is set to be lower than the first pipe 341; specifically, the secondary compression system 22 adopts a pre-cooling treatment method, the first pipe 341 in the condenser module 30 is used to cool the exhaust gas of the low temperature compressor, and at the same time the oil separator 222 is sunken, that is, lower than the first pipe 341, which is conducive to the recovery of compressor lubricating oil in the condenser module 30 and helps the refrigeration process.

[0056] Specifically, the oil separator 222 is preferably slightly lower than the first pipeline 341. In order to ensure that the oil separator 222 is always in an effective position lower than the first pipeline 341 during installation, the height of the oil separator 222 is preferably adjustable. For example, a threaded part 2221 is provided at the bottom of the oil separator 222, which is connected to the bottom wall 11, and the height of the oil separator 222 can be adjusted within a certain range during installation.

[0057] like Figures 7-8 As shown, the regenerator 50 of this embodiment includes a shell 51 and an intermediate conductive pipe 52. The shell 51 has a regenerating cavity 511, and the intermediate conductive pipe 52 is disposed inside the shell 51 and isolated from the regenerating cavity 511 to provide heat exchange space. Preferably, the shell 51 is cylindrical to provide sufficient heat exchange space, and the intermediate conductive pipe 52 is spiral to increase the effective length of the intermediate conductive pipe 52 while keeping the length of the shell 51 unchanged, so as to achieve more complete heat exchange.

[0058] Specifically, the first inlet 50a of the regenerator 50 is connected to the second outlet of the heat exchanger 40, the first outlet 50b of the regenerator 50 is connected to the inlet end of the secondary capillary tube 224, the second inlet 50c of the regenerator 50 is connected to the outlet end of the evaporator 225, and the second outlet 50d of the regenerator 50 is connected to the return gas end of the secondary compressor 221.

[0059] In this embodiment of the invention, the two ends of the intermediate conductive pipe 52 form the first inlet 50a and the first outlet 50b of the regenerator 50, respectively. The second inlet 50c and the second outlet 50d of the regenerator 50 are both connected to the regenerating cavity 511. Correspondingly, in other embodiments, depending on the connection method, the two ends of the intermediate conductive pipe 52 can also form the second inlet and the second outlet of the regenerator 50, respectively, and the first inlet and the first outlet of the regenerator 50 are both connected to the regenerating cavity 511.

[0060] The cryogenic refrigeration system of this invention can not only effectively reduce the heat load inside the compressor compartment, but also effectively improve refrigeration efficiency and increase the cooling rate of the compressor compartment; such as Figure 9 As shown, the cryogenic refrigeration system of this embodiment of the invention takes 375.5 minutes to lower the temperature from room temperature to -86°C. Under the same experimental conditions, in contrast, in a conventional cryogenic refrigeration system, the refrigerant is discharged from the secondary compressor and directly enters the oil separator; simultaneously, when the refrigerant is drawn from the primary compressor, it first enters the condenser pipe, then the condenser, and finally exits the condenser into the primary dryer filter. Figure 10As shown, a traditional cryogenic refrigeration system takes 436.5 minutes to lower the temperature from room temperature to -86°C. The cryogenic refrigeration system of this invention reduces the cooling time by a full 61 minutes compared to existing cryogenic refrigeration systems, resulting in a significantly faster cooling rate and a substantial improvement in refrigeration efficiency.

[0061] While the present invention has been disclosed above with reference to specific embodiments, these embodiments are not intended to limit the scope of the invention. Any person skilled in the art can make variations / modifications without departing from the scope of the invention; all equivalent variations / modifications made in accordance with the present invention should be covered by the protection scope of the present invention.

Claims

1. A cryogenic refrigeration system, wherein the refrigeration system employs a dual-compressor cascade refrigeration method, comprising a primary compression system and a secondary compression system sharing a heat exchanger, characterized in that: The condenser module includes a first pipe, a second pipe, and a third pipe. The effective length of the first pipe does not exceed the effective length of the second pipe, the effective length of the second pipe does not exceed the effective length of the third pipe, and the first pipe, the second pipe, and the third pipe are stacked from top to bottom and are independent of each other. The inlet end of the first pipeline is connected to the exhaust end of the second-stage compressor in the two-stage compression system, and the outlet end of the first pipeline is connected to the first inlet of the heat exchanger. The inlet end of the second pipeline is connected to the exhaust end of the first-stage compressor in the first-stage compression system, and the outlet end of the second pipeline is connected to the inlet of the decondenser pipe in the first-stage compression system. The inlet end of the third pipeline is connected to the outlet end of the decondensation pipe, and the outlet end of the third pipeline is connected to the second inlet of the heat exchanger. The primary compression system further includes a primary dryer filter, a primary capillary tube, and a liquid receiver; the primary compressor, the decondenser tube, the condenser module, the primary dryer filter, the primary capillary tube, the heat exchanger, and the liquid receiver are connected in sequence. The two-stage compression system also includes an oil separator, a two-stage dryer filter, a two-stage capillary tube, and an evaporator; The secondary compressor, the condenser module, the oil separator, the secondary dryer filter, the heat exchanger, the secondary capillary tube, and the evaporator are connected in sequence; wherein, the top of the oil separator is configured to be lower than the first pipeline; The secondary compression system further includes a regenerator; the first inlet of the regenerator is connected to the second outlet of the heat exchanger, and the first outlet of the regenerator is connected to the inlet end of the secondary capillary tube; the second inlet of the regenerator is connected to the outlet end of the evaporator, and the second outlet of the regenerator is connected to the return gas end of the secondary compressor; wherein, the regenerator includes a shell and an intermediate conductive tube, the intermediate conductive tube being spiral-shaped; the shell has a regenerating cavity, the intermediate conductive tube being disposed within the shell and isolated from the regenerating cavity; the two ends of the intermediate conductive tube respectively form the first inlet and the first outlet of the regenerator, and the second inlet and the second outlet of the regenerator are both connected to the regenerating cavity; or, the two ends of the intermediate conductive tube respectively form the second inlet and the second outlet of the regenerator, and the first inlet and the first outlet of the regenerator are both connected to the regenerating cavity.

2. The cryogenic refrigeration system as described in claim 1, characterized in that: The condenser module includes a housing, a fan, and fins; The first pipe, the second pipe, and the third pipe are mounted on the housing; The fan is mounted on the housing and located on the opposite side of the first pipe, the second pipe, and the third pipe; The fins are installed on the first pipe, the second pipe, and the third pipe.

3. The cryogenic refrigeration system as described in claim 1, characterized in that: The outlet end of the primary capillary is connected to the first inlet of the heat exchanger, and the first outlet of the heat exchanger is connected to the inlet end of the liquid reservoir; the outlet end of the secondary drying filter is connected to the second inlet of the heat exchanger, and the second outlet of the heat exchanger is connected to the inlet end of the secondary capillary.

4. The cryogenic refrigeration system as described in claim 1, characterized in that: The heat exchanger is a tubular heat exchanger.

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