Liquid nitrogen generating system

Abstract

The invention relates to the technical field of liquid nitrogen generating equipment, and discloses a liquid nitrogen generating system, through a set of refrigerant refrigerating system, heat dissipation of the hot end of a Stirling cryocooler and cooling and drying of compressed air can be achieved at the same time, the system structure is simpler, and the occupied space is smaller.

Description

Technical Field

[0001] This application relates to the field of liquid nitrogen generating equipment technology, such as a liquid nitrogen generating system. Background Technology

[0002] The cooling system is the core functional unit of a liquid nitrogen generator, and its performance directly affects the overall liquid nitrogen production efficiency, operational reliability, and energy consumption level. Currently, liquid nitrogen generators mainly involve two key cooling aspects: first, cooling and drying the compressed air at the nitrogen source to remove moisture and ensure nitrogen purity and the safety of subsequent equipment; second, efficiently dissipating heat from the hot end of the Stirling chiller—the core of nitrogen liquefaction—to maintain its optimal operating temperature difference and ensure liquefaction efficiency.

[0003] In related technologies, discrete solutions are commonly used in the industry to achieve the aforementioned cooling functions. For the cooling and drying of compressed air, air coolers or thermoelectric refrigerated dryers are typically used. For heat dissipation at the hot end of the Stirling refrigerator, air-cooling or water-cooling solutions are employed depending on the power rating.

[0004] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art: In related technologies, the cooling function of liquid nitrogen generators is achieved by piecing together multiple independent subsystems, namely air-cooled / water-cooled radiators and air coolers / refrigerated dryers, resulting in a complex system structure and large space occupation.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0006] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0007] This disclosure provides a liquid nitrogen generation system that, through a refrigerant refrigeration system, can simultaneously dissipate heat from the hot end of a Stirling refrigerator and cool and dry compressed air. The system structure is simpler and occupies less space.

[0008] This disclosure provides a liquid nitrogen generation system comprising: a liquid nitrogen tank assembly, a liquid nitrogen generation assembly, and a refrigeration assembly. The liquid nitrogen tank assembly includes a Stirling refrigerator and a radiator, the radiator having a heat dissipation cavity, the hot end of the Stirling refrigerator being housed within the heat dissipation cavity; the liquid nitrogen generation assembly includes an air compressor for generating compressed air; the refrigeration assembly includes a radiator and a heat exchanger connected in sequence, the radiator having a heat dissipation cavity, and a cryogenic refrigerant flowing within the heat dissipation cavity and the heat exchanger; wherein the hot end of the Stirling refrigerator is housed within the heat dissipation cavity, and the air compressor is connected to the heat exchanger to deliver compressed air to the heat exchanger.

[0009] In some embodiments, the refrigeration assembly further includes a refrigeration compressor, a condenser, and an expansion valve, wherein the refrigeration compressor, condenser, expansion valve, radiator, and heat exchanger are connected in sequence; wherein the heat exchanger is configured as an evaporator.

[0010] In some embodiments, the refrigeration assembly further includes a dryer filter. The dryer filter is connected between the condenser and the expansion valve and is used to dry and filter the refrigerant flowing through it.

[0011] In some embodiments, the refrigeration assembly further includes a liquid receiver. The liquid receiver is disposed between the condenser and the dryer filter, and the inlet and outlet of the liquid receiver are respectively connected to the condenser and the dryer filter.

[0012] In some embodiments, the radiator includes a heat dissipation housing. The heat dissipation housing is provided with a heat dissipation cavity, a first connecting pipe and a second connecting pipe, the first connecting pipe and the second connecting pipe being respectively connected to the heat dissipation cavity; wherein, the first connecting pipe is also connected to an expansion valve, and the second connecting pipe is also connected to a heat exchanger.

[0013] In some embodiments, the radiator further includes fins. The fins are disposed within the heat dissipation cavity and are in contact with the hot end of the Stirling refrigerator.

[0014] In some embodiments, the hot end of the Stirling refrigerator is configured as a cylindrical or columnar structure; the ribs are configured as annular structures corresponding to the hot end structure of the Stirling refrigerator, and the inner edge of the ribs is connected to the outer wall surface of the hot end of the Stirling refrigerator.

[0015] In some embodiments, the heat sink includes a plurality of fins, and the plurality of fins are arranged in parallel in the heat dissipation cavity.

[0016] In some embodiments, the spacing between the plurality of fins is greater than or equal to a preset distance to form a flow channel within the heat dissipation cavity; wherein the first connecting pipe and the second connecting pipe are respectively connected to the flow channel.

[0017] In some embodiments, the liquid nitrogen generation system further includes a support frame. The support frame is used to mount the liquid nitrogen tank assembly, the liquid nitrogen generation assembly, and the refrigeration assembly.

[0018] The liquid nitrogen generation system provided in this disclosure can achieve the following technical effects: This disclosure provides a liquid nitrogen generation system comprising: a liquid nitrogen tank assembly, a liquid nitrogen generating assembly, and a refrigeration assembly. The liquid nitrogen tank assembly includes a Stirling refrigerator; the liquid nitrogen generating assembly includes an air compressor for generating compressed air; the refrigeration assembly includes a radiator and a heat exchanger connected in sequence, the radiator having a heat dissipation cavity, and a cryogenic refrigerant flowing within the heat dissipation cavity and the heat exchanger; wherein the hot end of the Stirling refrigerator is housed within the heat dissipation cavity, and the air compressor is connected to the heat exchanger to supply compressed air to the heat exchanger. Thus, during system operation, the cryogenic refrigerant in the refrigeration system first flows through a pipeline to the heat dissipation cavity of the radiator, and then the cryogenic refrigerant in the heat dissipation cavity flows through a pipeline to the heat exchanger. At this time, the cryogenic refrigerant in the heat dissipation cavity can directly cool the hot end of the Stirling refrigerator, and the cryogenic refrigerant in the heat exchanger can cool and dry the compressed gas within the heat exchanger. With this configuration, a single refrigerant refrigeration system can simultaneously dissipate heat from the hot end of the Stirling refrigerator and cool and dry the compressed air, resulting in a simpler system structure and smaller footprint.

[0019] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a schematic diagram of a liquid nitrogen generation system provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of another liquid nitrogen generation system provided in an embodiment of this disclosure; Figure 3 This is a schematic diagram of the structure of a liquid nitrogen tank assembly provided in an embodiment of this disclosure; Figure 4 This is a cross-sectional structural schematic diagram of a liquid nitrogen tank assembly provided in an embodiment of this disclosure; Figure 5 This is a magnified view of a portion of the structure of 4; Figure 6 This is a schematic diagram of the structure of a refrigeration component provided in an embodiment of this disclosure; Figure 7 This is a schematic diagram of the structure of a liquid nitrogen generating component provided in an embodiment of this disclosure.

[0021] Figure label: 11: Liquid nitrogen tank assembly; 12: Liquid nitrogen generating assembly; 13: Refrigeration assembly; 14: Support frame; 141: Frame; 142: Support plate; 143: Wheels; 21: Stirling refrigerator; 211: Cold end; 212: Hot end; 22: Tank; 23: Level gauge; 24: Nitrogen inlet valve; 25: Liquid nitrogen outlet valve; 31: Air compressor; 32: Filter; 33: Dryer; 34: Nitrogen generator module; 41: Radiator; 411: First connecting pipe; 412: Second connecting pipe; 413: Heat dissipation cavity; 414: Fin; 42: Heat exchanger; 43: Refrigeration compressor; 44: Condenser; 45: Liquid receiver; 46: Expansion valve. Detailed Implementation

[0022] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0023] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0024] In this disclosure, the terms "upper," "lower," "inner," "middle," "outer," "front," and "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for better description of the embodiments of this disclosure and their implementations, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to require them to be constructed and operated in a specific orientation. Furthermore, some of the aforementioned terms may be used to indicate other meanings besides orientation or positional relationship; for example, the term "upper" may in some cases indicate a dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the embodiments of this disclosure according to the specific circumstances.

[0025] Furthermore, the terms "set up," "connect," and "fix" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this disclosure according to the specific circumstances.

[0026] Unless otherwise stated, the term "multiple" means two or more.

[0027] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0028] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present disclosure can be combined with each other.

[0030] like Figures 1 to 7 As shown, this embodiment of the present disclosure provides a liquid nitrogen generation system that can simultaneously dissipate heat from the hot end 212 of the Stirling refrigerator 21 and cool and dry the compressed air through a refrigerant refrigeration system. The system structure is simpler and occupies less space.

[0031] like Figures 1 to 7 As shown, this disclosure provides a liquid nitrogen generation system comprising: a liquid nitrogen tank assembly 11, a liquid nitrogen generation assembly 12, and a refrigeration assembly 13. The liquid nitrogen tank assembly 11 includes a Stirling refrigerator 21; the liquid nitrogen generation assembly 12 includes an air compressor 31 for generating compressed air; the refrigeration assembly 13 includes a radiator 41 and a heat exchanger 42 connected in sequence, the radiator 41 having a heat dissipation cavity 413, and a cryogenic refrigerant flowing within the heat dissipation cavity 413 and the heat exchanger 42; wherein the hot end 212 of the Stirling refrigerator 21 is housed within the heat dissipation cavity 413, and the air compressor 31 is connected to the heat exchanger 42 to deliver compressed air to the heat exchanger 42.

[0032] Specifically, the liquid nitrogen tank assembly 11 further includes a tank body 22 for storing liquid nitrogen. The cold end 211 of the Stirling refrigerator 21 is arranged corresponding to the opening of the tank body 22 to liquefy the nitrogen in the tank body 22 by the refrigeration of the Stirling refrigerator 21. The refrigeration assembly 13 includes a closed refrigeration cycle circuit for the refrigerant to circulate. The refrigeration cycle circuit is sequentially connected to the heat dissipation cavity 413 of the radiator 41 and the heat exchanger 42, so that the low-temperature refrigerant flows into the heat dissipation cavity 413 and the heat exchanger 42 in sequence. The size of the heat dissipation cavity 413 is larger than the size of the hot end 212 of the Stirling refrigerator 21. After the hot end 212 is accommodated in the heat dissipation cavity 413, there is a gap between the hot end 212 and the inner wall of the heat dissipation cavity 413, and a flow channel for the refrigerant to flow is constructed through this gap. The outlet end of the heat dissipation cavity 413 and the inlet end of the heat exchanger 42 are also connected through the refrigeration cycle circuit, so that the low-temperature refrigerant in the heat dissipation cavity 413 flows into the heat exchanger 42 through the refrigeration cycle circuit. The liquid nitrogen generating assembly 12 further includes an air circulation pipeline. After the air compressor 31 prepares compressed air, the compressed air flows into the heat exchanger 42 through the air circulation pipeline. In this way, the high-temperature compressed air output from the air compressor 31 is transported to the heat exchanger 42. At the same time, when the low-temperature refrigerant in the refrigeration assembly 13 flows through the heat dissipation cavity 413 of the radiator 41, it absorbs the waste heat generated by the hot end 212 of the Stirling refrigerator 21, and then flows through the heat exchanger 42, where it exchanges heat with the high-temperature compressed air from the air compressor 31 to pre-cool and dry the compressed air. Finally, the preliminarily cooled and dried compressed air is sent to the subsequent nitrogen production module 34 to produce high-purity nitrogen, and the high-purity nitrogen is finally liquefied at the cold end 211 of the Stirling refrigerator 21. With such a setting, through a set of refrigerant refrigeration systems, it is possible to simultaneously dissipate heat from the hot end 212 of the Stirling refrigerator 21 and cool and dry the compressed air, making the system structure simpler and occupying less space.

[0033] It can be understood that the liquefaction efficiency of the Stirling refrigerator 21 extremely depends on whether its hot end 212 can be continuously and stably and effectively cooled. If the temperature of the hot end 212 is too high or fluctuates too much, it will directly cause the temperature of the cold end 211 to rise, the liquefaction capacity to drop sharply, and even the machine to stop. If the compressed air is cooled first and then the hot end 212 of the Stirling refrigerator 21 is cooled, the flow rate and temperature fluctuations of the compressed air may cause fluctuations in the state of the refrigerant. If this fluctuation is first transmitted to the radiator 41 of the Stirling hot end 212, it may cause unstable heat dissipation conditions, thereby affecting the liquefaction performance. Therefore, placing the radiator 41 at the front end of the heat dissipation process can ensure that the refrigerant coming out of the refrigeration compressor 43 with the most stable state and the greatest heat exchange potential is preferentially used to cool the Stirling hot end 212. This provides a stable heat dissipation guarantee for the Stirling refrigerator 21 and ensures the stable operation of the core and bottleneck links in the entire liquid nitrogen production process.

[0034] Furthermore, since the hot end 212 of the Stirling refrigerator 21 has a high temperature, typically reaching 50°C or even higher, it is a high-temperature heat source. The compressed air, however, needs to be cooled to a dew point temperature typically around 2-10°C, making it a low-temperature heat source. Therefore, the refrigerant first enters the radiator 41 to exchange heat with the high-temperature Stirling hot end 212. At this point, the refrigerant's evaporation temperature can be designed to be relatively high, efficiently removing heat. In this way, the system only needs to expend less compression work to generate cooling capacity at this temperature level. Then, after absorbing heat from the Stirling hot end 212, the refrigerant, flowing through the heat exchanger 42, still maintains a temperature / pressure state sufficient to cool the compressed air to the required dew point temperature. The refrigerant continues to evaporate during this process, completing the cooling of the compressed air. This flow path design achieves tiered energy utilization, using the same refrigerant to first address high-temperature cooling needs and then low-temperature cooling needs, matching the quality of cooling capacity with the temperature of the heat source, thereby optimizing the overall energy efficiency of the system.

[0035] like Figures 1 to 5 As shown, optionally, the liquid nitrogen tank assembly 11 also includes a level gauge 23, a pressure transmitter, a nitrogen inlet valve 24, and a liquid nitrogen outlet valve 25. During liquid nitrogen production, the control system first opens the nitrogen inlet valve 24. High-purity nitrogen gas enters the tank 22 through the opened inlet valve 24 and is guided to the cold end 211 of the Stirling refrigerator 21. When the high-purity nitrogen gas comes into contact with the cold end 211, heat is rapidly carried away, the gaseous nitrogen is condensed into liquid nitrogen, and drips and collects in the liquid nitrogen tank below. Furthermore, the level gauge 23 monitors the liquid nitrogen level in the tank 22 in real time, and the pressure transmitter monitors the pressure in the tank 22 in real time. When liquid nitrogen needs to be output, the liquid nitrogen outlet valve 25 is opened, and then the liquid nitrogen in the tank 22 is output.

[0036] like Figures 1 to 7 As shown, optionally, the liquid nitrogen generating assembly 12 also includes a filter 32, a dual-tower adsorption dryer 33, and a PSA (Pressure Swing Adsorption) nitrogen generation module 34. The air compressor 31 is configured as an oil-free reciprocating air compressor. The oil-free reciprocating air compressor starts, draws in ambient air, and compresses it. The resulting high-temperature, high-pressure compressed air is first sent to a heat exchanger 42 and forcibly cooled by a low-temperature refrigerant, lowering the temperature below the dew point. At this point, most of the water vapor in the compressed air condenses into liquid water and is separated. After cooling and preliminary dehumidification, the compressed air passes through the filter 32 and then enters the dual-tower adsorption dryer 33. The deeply dried compressed air finally enters the PSA nitrogen generation module 34.

[0037] like Figures 1 to 6As shown, in some embodiments, the refrigeration assembly 13 further includes a refrigeration compressor 43, a condenser 44, and an expansion valve 46, wherein the refrigeration compressor 43, the condenser 44, the expansion valve 46, the radiator 41, and the heat exchanger 42 are connected in sequence; wherein the heat exchanger 42 is configured as an evaporator.

[0038] Specifically, the condenser 44 is also equipped with a cooling fan for heat dissipation. In the condenser 44, the refrigerant releases heat to the external environment, and the cooling fan forces ventilation. As heat dissipates, the high-temperature, high-pressure gaseous refrigerant gradually condenses, transforming into a medium-temperature, high-pressure liquid refrigerant. The medium-temperature, high-pressure liquid refrigerant in the condenser 44 flows through the expansion valve 46, which throttles and reduces the pressure of the liquid refrigerant, causing its pressure and temperature to drop sharply. After exiting the expansion valve 46, the refrigerant becomes a low-temperature, low-pressure gas-liquid two-phase mixture. The low-temperature, low-pressure gas-liquid mixture refrigerant exiting the expansion valve 46 first flows through the heat dissipation chamber 413 of the radiator 41. Here, the refrigerant absorbs the waste heat emitted by the hot end 212 of the Stirling refrigerator 21 contained in the heat dissipation chamber 413, and the refrigerant begins to evaporate. Subsequently, the refrigerant continues to flow to the heat exchanger 42, where it exchanges heat with the high-temperature compressed air of the liquid nitrogen generating assembly 12, further absorbing heat from the compressed air and cooling and drying it. At the same time, the refrigerant itself completely evaporates, becoming a low-temperature, low-pressure superheated gas. The low-temperature, low-pressure superheated gas exiting the heat exchanger 42 is eventually drawn back into the refrigeration compressor 43, starting a new refrigeration cycle.

[0039] like Figures 1 to 6 As shown, in some embodiments, the refrigeration assembly 13 further includes a dryer filter. The dryer filter is connected between the condenser 44 and the expansion valve 46 for drying and filtering the refrigerant flowing through it.

[0040] Specifically, a dryer filter is installed in series between the outlet of the condenser 44 and the inlet of the expansion valve 46. The high-pressure liquid refrigerant, liquefied in the condenser 44, must flow through the dryer filter before flowing to the expansion valve 46. This arrangement, by preventing ice blockage and physical blockage, ensures that the refrigerant can flow continuously and stably in the closed loop formed by the refrigeration compressor 43, condenser 44, dryer filter, expansion valve 46, radiator 41, and heat exchanger 42.

[0041] like Figures 1 to 6 As shown, in some embodiments, the refrigeration assembly 13 further includes a liquid receiver 45. The liquid receiver 45 is disposed between the condenser 44 and the dryer filter, and the inlet and outlet of the liquid receiver 45 are respectively connected to the condenser 44 and the dryer filter.

[0042] Specifically, the receiver 45 is installed in series in the refrigeration circuit. Its inlet is directly connected to the outlet of the condenser 44, and its outlet is connected to the inlet of the dryer filter. Therefore, the liquid refrigerant flowing out of the condenser 44 first enters the receiver 45, and then flows from its outlet to the dryer filter and the subsequent expansion valve 46. When the heat load decreases, the condensation effect increases, and the amount of liquid refrigerant in the condenser 44 increases. The receiver 45 can provide additional volume to accommodate the excess liquid refrigerant. Conversely, when the heat load increases, the system's demand for liquid refrigerant increases. The receiver 45 can replenish the liquid refrigerant stored inside to the circulation in a timely manner, ensuring that the radiator 41 and heat exchanger 42 receive sufficient liquid supply, thereby maintaining the system's cooling capacity.

[0043] like Figures 1 to 5 As shown, in some embodiments, the radiator 41 includes a heat dissipation housing. The heat dissipation housing is provided with a heat dissipation cavity 413, a first connecting pipe 411 and a second connecting pipe 412, the first connecting pipe 411 and the second connecting pipe 412 being respectively connected to the heat dissipation cavity 413; wherein, the first connecting pipe 411 is also connected to the expansion valve 46, and the second connecting pipe 412 is also connected to the heat exchanger 42.

[0044] Specifically, a sealed, hollow heat dissipation cavity 413 is machined or cast inside the casing, and the hot end 212 of the Stirling refrigerator 21 is directly installed inside the heat dissipation cavity 413. The heat dissipation casing is provided with a first connecting pipe 411 and a second connecting pipe 412, which are respectively connected to the two ends of the heat dissipation cavity 413, forming channels for refrigerant inflow and outflow. The first connecting pipe 411 serves as the refrigerant inlet, connected to the outlet of the expansion valve 46 in the system via a pipeline. The low-temperature, low-pressure gas-liquid mixture of refrigerant from the expansion valve 46 enters the heat dissipation cavity 413 through the first connecting pipe 411. The second connecting pipe 412 serves as the refrigerant outlet, connected to the inlet of the heat exchanger 42 in the system via a pipeline. After absorbing heat from the Stirling hot end 212 in the heat dissipation cavity 413, the refrigerant temperature rises and partially evaporates, then flows out through the second connecting pipe 412 to the next cooling station.

[0045] like Figures 1 to 5 As shown, in some embodiments, the radiator 41 further includes fins 414. The fins 414 are disposed within the heat dissipation cavity 413 and are in contact with the hot end 212 of the Stirling refrigerator 21.

[0046] Specifically, the inner edge of the fin 414 extends toward the hot end 212 of the Stirling refrigerator and directly contacts the hot end 212. With this configuration, firstly, the hot end 212 of the Stirling refrigerator transfers heat to the fin 414, and then the fin 414 directly contacts the low-temperature refrigerant to increase the effective heat exchange area. Secondly, when the refrigerant flows through the fin 414, it generates eddies and disturbances, which effectively thins the boundary layer adhering to the wall of the hot end 212 of the Stirling refrigerator. This disturbance enhances turbulent heat transfer, allowing the lower-temperature refrigerant in the central region of the flow channel to mix and contact more fully with the high-temperature fin 414 and the hot end 212 of the Stirling refrigerator.

[0047] like Figure 5 As shown, in some embodiments, the hot end 212 of the Stirling refrigerator 21 is configured as a cylindrical or columnar structure; the rib 414 is configured as an annular structure corresponding to the structure of the hot end 212 of the Stirling refrigerator 21, and the inner edge of the rib 414 is connected to the outer wall surface of the hot end 212 of the Stirling refrigerator 21.

[0048] Specifically, configuring the hot end 212 of the Stirling refrigerator as a cylindrical or columnar structure is more conducive to the uniform radial conduction of heat from the inside of the hot end 212 to its outer wall surface. The fins 414 are specifically configured as annular structures, with the inner edge of each annular fin 414 directly fitting the outer wall surface of the hot end 212 of the Stirling refrigerator 21. The inner edge of the annular fin 414 and the outer wall surface of the cylindrical hot end 212 are connected firmly and with low thermal resistance through processes such as interference fit, welding, or high thermal conductivity adhesives, ensuring that heat can be conducted unimpeded and directly from the outer wall of the hot end 212 to the entire fin 414. With this configuration, firstly, the combination of the annular fins 414 and the cylindrical hot end 212 achieves a wrap-around contact. Compared to heat dissipation methods that connect only from one side or a part of the area, this design makes the heat conduction path the shortest and the contact area the largest. Secondly, the symmetrical annular structure allows heat to be transferred evenly from the hot end 212 to the surrounding area in a radial manner, avoiding the problem of local overheating that may be caused by the asymmetry of the heat sink 41 structure, and making the overall temperature field of the hot end 212 more uniform.

[0049] like Figure 5 As shown, in some embodiments, the heat sink 41 includes a plurality of fins 414, and the plurality of fins 414 are arranged in parallel to the heat dissipation cavity 413.

[0050] Specifically, multiple fins 414 are spaced apart along the axial direction of the hot end 212 of the Stirling refrigerator. Temperature differences may exist at different axial positions of the hot end 212 of the Stirling refrigerator 21. The multiple parallel fins 414 distributed along the axial direction can simultaneously dissipate heat from various sections of the hot end 212.

[0051] like Figure 5As shown, in some embodiments, the spacing between the plurality of ribs 414 is greater than or equal to a preset distance to form a flow channel in the heat dissipation cavity 413; wherein, the first pipe 411 and the second pipe 412 are respectively connected to the flow channel.

[0052] Specifically, the outer edge of the fin 414 is directly connected to the inner wall of the heat dissipation cavity 413, and multiple fins 414 form one or more annular flow channels within the heat dissipation cavity 413. If multiple flow channels exist within the heat dissipation cavity 413, these channels can be interconnected or isolated from each other. The first connecting pipe 411 is simultaneously connected to multiple flow channels, and the second connecting pipe 412 is also simultaneously connected to multiple flow channels. In this way, the low-temperature refrigerant can flow into multiple annular flow channels simultaneously through the first connecting pipe 411, and flow around the periphery of the hot end 212 of the Stirling refrigerator 21 along the annular flow channels, and then flow out of the heat dissipation cavity 413 through the second connecting pipe 412.

[0053] In practical applications, the spacing between any two adjacent fins 414 can be set according to the viscosity and density of the refrigerant, the target flow rate and pressure drop.

[0054] like Figure 1 As shown, in some embodiments, the liquid nitrogen generation system further includes a support 14. The support 14 is used to mount the liquid nitrogen tank assembly 11, the liquid nitrogen generation assembly 12, and the refrigeration assembly 13.

[0055] Specifically, the support frame 14 includes a frame 141 and a support plate 142 for support. The frame 141 defines the installation area for the liquid nitrogen tank assembly 11, the liquid nitrogen generating assembly 12, and the refrigeration assembly 13. The support plate 142 is horizontally positioned in the installation area to divide the upper and lower halves of the installation area. The liquid nitrogen tank assembly 11 and the refrigeration assembly 13 are mounted on the bottom plate of the frame 141, meaning they are located in the lower half of the installation area; the liquid nitrogen generating assembly 12 is mounted on the support plate 142, meaning it is located in the upper half of the installation area. This arrangement allows the heavier liquid nitrogen tank assembly 11 and the refrigeration assembly 13 to be positioned in the lower half of the support frame 14, thus lowering the overall center of gravity of the equipment.

[0056] like Figure 1 As shown, optionally, the bottom of the bracket 14 is also provided with wheels 143 to facilitate the user's movement of the liquid nitrogen generating system.

[0057] The foregoing description and accompanying drawings fully illustrate embodiments of the present disclosure to enable those skilled in the art to practice them. Other embodiments may include structural and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included or substituted for parts and features of other embodiments. Embodiments of the present disclosure are not limited to the structures described above and shown in the accompanying drawings, and various modifications and changes may be made without departing from its scope. The scope of the present disclosure is limited only by the appended claims.

Claims

1. A liquid nitrogen generating system, characterized by, The system comprises: a liquid nitrogen tank assembly (11) comprising a Stirling refrigerator (21); a liquid nitrogen generating assembly (12) comprising an air compressor (31) for preparing compressed air; and a refrigeration assembly (13) comprising a heat sink (41) and a heat exchanger (42) connected in sequence, the heat sink (41) is provided with a heat dissipation cavity (413), and the heat dissipation cavity (413) and the heat exchanger (42) are filled with low-temperature refrigerant. The hot end (212) of the Stirling refrigerator (21) is contained in the heat dissipation cavity (413), and the air compressor (31) is connected to the heat exchanger (42) to supply compressed air to the heat exchanger (42).

2. The system according to claim 1, wherein the refrigeration assembly (13) further comprises a refrigeration compressor (43), a condenser (44) and an expansion valve (46), and the refrigeration compressor (43), the condenser (44), the expansion valve (46), the heat sink (41) and the heat exchanger (42) are connected in sequence. The heat exchanger (42) is configured as an evaporator. The refrigeration assembly (13) further comprises: a drying filter (32) connected between the condenser (44) and the expansion valve (46) for drying and filtering the refrigerant flowing therethrough.

3. The liquid nitrogen generating system of claim 2, wherein, The refrigeration assembly (13) further comprises: a liquid accumulator (45) arranged between the condenser (44) and the drying filter (32), and the inlet and outlet of the liquid accumulator (45) are connected to the condenser (44) and the drying filter (32) respectively.

4. The liquid nitrogen generating system of claim 3, wherein, The heat sink (41) comprises: a heat dissipation housing provided with a heat dissipation cavity (413), a first connecting pipe and a second connecting pipe, and the first connecting pipe and the second connecting pipe are connected to the heat dissipation cavity (413) respectively.

5. The liquid nitrogen generating system of claim 2, wherein, The first connecting pipe is further connected to the expansion valve (46), and the second connecting pipe is further connected to the heat exchanger (42). The heat sink (41) further comprises: a fin (414) arranged in the heat dissipation cavity (413), and the fin (414) is in contact with the hot end (212) of the Stirling refrigerator (21).

6. The liquid nitrogen generating system of claim 5, wherein, 7. The system according to claim 6, wherein the hot end (212) of the Stirling refrigerator (21) is configured as a cylindrical structure or a columnar structure; and the fin (414) is configured as a circular ring structure corresponding to the structure of the hot end (212) of the Stirling refrigerator (21), and the inner edge of the fin (414) is connected to the outer wall surface of the hot end (212) of the Stirling refrigerator (21).

8. The system according to claim 7, wherein the heat sink (41) comprises a plurality of fins (414), and the plurality of fins (414) are arranged in parallel in the heat dissipation cavity (413).

9. The system according to claim 8, wherein ​ ​ ​ ​ The distance between the plurality of fins (414) is greater than or equal to a preset distance, so as to form a flow channel in the heat dissipation cavity (413); The first connecting pipe and the second connecting pipe are respectively communicated with the flow channel.

10. The liquid nitrogen generating system according to any one of claims 1 to 9, characterized by, Further comprising: A support (14) for mounting the liquid nitrogen tank assembly (11), the liquid nitrogen generating assembly (12) and the refrigeration assembly (13).

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