CN114322349B - A low temperature storage system with a DC coupled regenerative chiller - Google Patents

Abstract

The invention relates to a low-temperature storage system cooled by a coupled direct-current regenerative refrigerator, which comprises a regenerative refrigeration module and a low-temperature storage module; the regenerative refrigeration module comprises a regenerative refrigerator unit and a direct current circulation unit; the regenerative refrigerator unit comprises a compressor device, a heat regenerator and a cold end heat exchanger which are connected in sequence; the direct current circulation unit comprises a dividing wall type heat exchange channel, wherein direct current is led out of the regenerator from any position and led into the dividing wall type heat exchange channel, and the direct current directly or indirectly cools a heat leakage channel of the low-temperature storage module and then returns to the upper part of the regenerator, so that direct current circulation is completed. Compared with the prior art, the invention can effectively reduce the heat leakage of the low-temperature storage module by utilizing the cold quantity carried by direct current, thereby reducing the energy consumption of the low-temperature storage system and improving the efficiency of the low-temperature storage system.

Description

A low temperature storage system with a DC coupled regenerative chiller

Technical Field

The present invention relates to the field of refrigeration technology, and in particular to a low-temperature storage system cooled by a direct current coupled heat recovery refrigerator.

Background technique

The regenerative refrigerator is a refrigeration technology with alternating flow. It uses a regenerator to achieve periodic heat storage and release between the gas working medium and the regenerative filler, and uses the expansion of the gas to produce a refrigeration effect. The regenerator generally has a large specific surface area per unit volume, and the structural forms include wire mesh, pellet filler, gap type, etc. The regenerative cryogenic refrigerator has the advantages of high reliability, simple structure, and high efficiency. It is widely used in low-temperature technologies such as gas liquefaction and superconducting cooling.

Direct current is when the airflow masses of the forward and reverse flows in a certain cross section are not equal in one cycle, resulting in a net mass flow in one direction. Direct current is also called direct current circulating mass flow.

Cryogenic storage is a technology that maintains a certain material at a temperature far below room temperature. Storage is generally relatively static, and the main purpose is to maintain the state of the material, maintain low temperature, high density, purity, etc. Cryogenic transportation is a technology that transmits a certain material at a temperature far below room temperature and a certain pressure through a certain channel. The material generally moves relative to the channel. The insulation structure of cryogenic transportation is basically the same as the insulation structure of the storage system. Cryogenic storage and transportation are very important for the storage and transportation of various cryogenic liquids such as liquid helium, liquid hydrogen, and liquefied natural gas (LNG). Applications include the storage of liquid helium in superconducting nuclear magnetic resonance systems (MRI), the storage of liquid hydrogen in liquid hydrogen refueling stations, liquid hydrogen tank trucks and ships, etc.

The structure of low-temperature storage generally includes inner container, outer shell, intermediate insulation structure, support structure, material inlet and outlet pipeline, measurement signal channel, etc. The inner container is the structure in direct contact with the low-temperature material, the outer shell is the structure in direct contact with the external environment, the intermediate insulation structure includes low thermal conductivity stacking materials, radiation screen, cooling screen, etc. according to different structural forms, and the support structure is to fix the inner container in a certain position through the action of a certain force. The material inlet and outlet pipeline is the channel for putting materials into and taking out of the container, as well as the auxiliary discharge pipeline, including the neck pipe, exhaust pipe, inflation and pressure pipe, etc. The measurement signal channel is the channel for measuring information such as temperature, pressure, and liquid level. The support structure, material inlet and outlet pipeline, and measurement signal channel generally connect the inner container (or material) at low temperature and the room temperature part of the outside world, causing heat loss. The radiation screen is a low-emissivity film material, often made of aluminum foil or aluminum-plated film, and low-thermal conductivity spacers are often added between the multi-layer radiation screens. The cooling screen, also known as the steam cooling screen, or the steam cooling radiation screen, is a thin material that receives a certain amount of cooling, so that the radiation temperature in the middle is lower, and metal foil is often used.

The intermediate insulation structure of low-temperature storage includes ordinary non-vacuum stacked insulation, vacuum powder and fiber insulation, high vacuum insulation, vacuum multi-layer insulation, etc. The vacuum greatly reduces the gas heat conduction and convection heat transfer between the inner container and the outer shell, while the high reflectivity radiation material significantly reduces the radiation heat transfer. Therefore, the vacuum multi-layer insulation has the best insulation effect, and the apparent thermal conductivity is about ^10-4 , ^10-2 , and ^10-2 of the first three structures. Therefore, vacuum multi-layer insulation is the most widely used in current low-temperature storage.

The heat leakage channel is formed by temperature difference and transmitted to the inner container in the three forms of heat transfer: conduction, convection and radiation. Specifically, it includes cooling screen, radiation screen, stacked material, support structure, material inlet and outlet pipeline, measurement signal channel, stacked material, powder material, fiber material, etc.

However, there is still a certain amount of radiation heat leakage in the vacuum multi-layer insulation structure, heat conduction through multi-layer materials, heat transfer of residual gas molecules and heat conduction of related structures (support, material inlet and outlet pipes, measurement signal channels), which makes the heat leakage much higher than the heat leakage calculated by the ideal radiation attenuation model. In fact, the heat flow entering the cryogenic insulation cylinder through the support structure, material inlet and outlet pipes (including neck tubes), and measurement signal channels accounts for a very large proportion of the total heat flow, even reaching a size comparable to the radiation heat leakage.

The vacuum multi-layer insulation using pre-cooling cooling screens can absorb part of the radiation heat leakage, heat conduction through multi-layer materials, heat transfer of residual gas molecules and heat conduction of related structures, thereby reducing the total heat leakage.

The prior art uses the cold end refrigeration capacity (temperature denoted as _Tc ) of the refrigerator (generally two-stage) to reliquefy the stored material, and uses the precooling stage (temperature denoted as _T1 ) to cool the cooling screen. However, no cooling capacity can be provided between the cold end temperature _Tc and the precooling stage temperature _T1 , and between the precooling stage temperature _T1 and the room temperature, that is, no cooling screen can be provided in those intervals, resulting in limited precooling effect.

For another form, in low-temperature storage without refrigeration machine reliquefaction, steam is often used to cool the cooling screen, and its sensible heat is used to reduce the temperature of the cooling screen, thereby reducing radiation heat leakage and reducing the evaporation rate. For the specific cooling form, for small-sized ones, heat is generally transferred through the neck tube; for large and medium-sized ones, steam is generally transported through pipelines to conduct heat with each layer of cooling screen. However, the steam after cooling the cooling screen cannot be liquefied again, resulting in a loss of storage capacity.

Summary of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a low-temperature storage system cooled by a heat-recovery refrigerator coupled with direct current. The cold in the form of sensible heat carried by the direct current of the heat-recovery refrigerator is used to directly or indirectly cool the insulation structure, thereby changing the temperature distribution of the insulation structure, lowering the temperature of the part near the low temperature, reducing the corresponding heat leakage, and improving the storage efficiency.

When the applicant was developing and conceiving the present technical solution, he believed that the patent with publication number CN112097422A disclosed "a high-efficiency liquefaction system of a heat recovery refrigerator using direct current". Although it has the advantage of a heat recovery refrigerator that draws out direct current for pre-cooling and liquefaction, the patent does not involve how to cool the insulating material by direct or indirect heat transfer and apply it to a low-temperature storage system.

The applicant further considered that the transportation of low-temperature materials, where the materials move relative to the inner container most of the time, generally adopts a transmission pipeline with a certain insulation structure. At present, the steam cooling screen is not used to enhance the insulation performance, resulting in large heat leakage along the pipeline, and generally no refrigerator is used for reliquefaction.

The purpose of the present invention can be achieved by the following technical solutions:

The object of the present invention is to protect a low temperature storage system cooled by a DC coupled regenerative refrigerator, comprising a regenerative refrigerator module and a low temperature storage module;

The regenerative refrigeration module comprises a regenerative refrigerator unit and a direct current circulation unit;

The regenerative refrigerator unit comprises a compressor device, a regenerator, and a cold end heat exchanger connected in sequence;

The DC circulation unit includes a partition-type heat exchange channel. DC is drawn out of the regenerator from any position and introduced into the partition-type heat exchange channel to directly or indirectly cool the heat leakage channel of the low-temperature storage module, and then returns to the upper part of the regenerator to complete the DC circulation.

The DC circulation unit is provided with a DC control valve, through which the DC flow rate is controlled;

The low temperature storage module includes cold material, storage container inner container and storage container outer shell. It also includes cooling screen, radiation screen, stacking material, support structure, material inlet and outlet pipeline, measurement signal channel, and cold carrying channel for heat exchange with cooling screen; the heat leakage channel includes cooling screen, radiation screen, stacking material, support structure, material inlet and outlet pipeline, and measurement signal channel.

Furthermore, the position of the direct current outlet regenerator is the cold end of the regenerator, or any position between the cold end of the regenerator and the hot end of the regenerator;

The DC is led out at one or more locations, thereby forming one DC or multiple DCs, and the corresponding cold end heat exchanger includes one of an internal gap structure, multiple internal gap structures, one partition-type heat exchanger, and multiple partition-type heat exchangers;

The position where the direct current self-partitioning heat exchange channel is introduced into the regenerator is the hot end of the regenerator or any position between the hot end of the regenerator and the cold end of the regenerator;

The partition-type heat exchange channel behind the direct current outlet heat regenerator includes a gap structure inside the refrigerator, a direct current outlet heat regenerator and a partition-type heat exchanger behind the wall of the refrigerator pressure container;

The internal gap structure includes a gap formed by the expansion piston and the cylinder, a gap formed by two or more layers of channels in the pressure-bearing pipe of the regenerator, and a gap formed by two or more layers of channels in the pressure-bearing pipe of the pulse tube.

Furthermore, the DC circulation unit is also provided with an expansion mechanism and a compression mechanism, and the DC is successively led out of the regenerator and the wall of the refrigerator pressure container and then connected to the expansion mechanism;

The expansion mechanism is a single expansion mechanism or a combination of multiple expansion mechanisms;

The expansion mechanism is arranged on one direct current or respectively on multiple direct currents;

The position of the expansion mechanism on the DC is the cold end or any position between the cold end and the hot end;

The compression mechanism includes a single compression mechanism or a combination of multiple compression mechanisms;

The compression mechanism is arranged on one direct current or respectively on a plurality of direct currents.

Furthermore, the direct current is led out from the partition-type heat exchange channel and then introduced into the regenerator, or introduced into the low-pressure component and then introduced into the regenerator, or driven by the high-pressure component, thereby forming a cycle;

The low-pressure component is a low-pressure pipeline or a low-pressure chamber formed by a one-way valve;

The high-pressure component is a high-pressure pipeline or a high-pressure chamber formed by setting a one-way valve.

Furthermore, the structure for transmitting cold energy between the regenerative refrigerator and the low-temperature storage module is one of a pipeline transmission cooling medium structure, a solid heat conduction structure, and a series-parallel combination structure of pipeline transmission and solid heat conduction;

The pipeline cooling low temperature storage module in the pipeline transmission cooling medium structure, the cooling medium includes the direct current directly led out from the regenerative refrigerator for cooling, the gas material in the low temperature storage module, and the coolant;

After the direct current flows through the low-temperature storage module, the gas and the coolant in the low-temperature storage module are subjected to the inter-wall heat exchange by the inter-wall heat exchanger outside the heat recovery refrigerator or the outer surface of the heat recovery refrigerator, cooled to a low temperature, and recirculated.

Furthermore, the coolant refers to a coolant having a different pressure or chemical composition than the gas in the regenerative refrigerator or storage system, including gas, liquid, solid or a mixture of two or three thereof.

The partition wall heat exchange structure of the feed and cylinder outer shell heat exchange component includes a pipeline for heat exchange by heat conduction and a structure for heat exchange by convection with the partition wall heat exchange structure.

When the gas material and the coolant are subjected to flow cooling, a booster mechanism such as a fan and a pump, as well as a flow control component can be added.

The cooling method of solid heat conduction is to connect the cooling screen, radiation screen, stacked materials, support structure, material inlet and outlet pipelines, measurement signal channels and other heat leakage channels and the internal gap structure of the refrigerator through solids, and then lead the direct current out of the heat regenerator and the partition heat exchanger behind the wall of the refrigerator pressure container.

Further, the heat leakage channel is a component of direct cooling, including one of a cooling screen, a radiation screen, a stacked material, a support structure, a material inlet and outlet pipeline, and a measurement signal channel. That is, the direct cooling components include a cooling screen, a stacked material, a support structure, a material inlet and outlet pipeline, a measurement signal channel, and the like, which are heat leakage channels that bring heat load to the central low-temperature storage container. The cooling screen includes one or more layers. The support structure, the material inlet and outlet pipeline, and the measurement signal channel include one or more.

Furthermore, the cooling medium and the supporting structure, the material inlet and outlet pipelines, and the measurement signal channel can flow in parallel to perform distributed cooling, and a number of heat exchange points can also be installed on the supporting member.

Furthermore, the insulation structure forms applicable to the low-temperature storage system cooled by the DC-coupled regenerative refrigerator are vacuum multilayer insulation, vacuum insulation, vacuum stacking insulation, ordinary stacking insulation (non-vacuum) insulation structures that reduce the three heat transfer modes of heat conduction/convection/radiation, and composite insulation forms of the above insulation structures. Among them, ordinary stacking insulation includes foaming materials, filling materials, aerogels, etc., and the structural forms of stacking materials in vacuum stacking insulation and ordinary stacking insulation include blocks, sheets, fibers, spheres, powders, etc.

For vacuum insulation, the cooling screen can be cooled. For vacuum stacked insulation and ordinary stacked insulation, the stacked insulation material can be cooled to absorb part of the radiation leakage heat, heat conduction, heat transfer of residual gas molecules and heat conduction of related structures (supports, material inlet and outlet pipelines, measurement signal channels), thereby reducing the total heat leakage.

Furthermore, the low-temperature storage module is a storage tank in which the material is basically stationary relative to the inner container, and a pipeline for transporting the material in which the material moves relative to the inner container.

Furthermore, the regenerative refrigerator unit is a refrigerator that uses a regenerator component to realize alternating storage and release of heat, including a hybrid structure in which one or more refrigerators selected from the group consisting of a GM refrigerator, a Solvay refrigerator, a Stirling refrigerator, a VM refrigerator, and a pulse tube refrigerator are multi-stage coupled;

The pulse tube refrigerator is a GM pulse tube refrigerator or a Stirling pulse tube refrigerator.

Furthermore, the regenerative refrigeration module is a regenerator built-in structure or a regenerator external structure;

In the regenerator built-in structure, the regenerator is built-in in the expansion piston;

In the external regenerator structure, the expansion piston and the regenerator are separately arranged;

The regenerative refrigeration module comprises a single-stage structure and a multi-stage coupling structure, wherein the multi-stage coupling structure comprises a multi-stage thermal coupling structure, a multi-stage gas coupling structure, and a thermal coupling and gas coupling mixed structure.

Furthermore, the average working pressure in the heat recovery refrigeration module is 0.1 to 3000 times the atmospheric pressure (0.01-300MPa), and the average working pressure in the low-temperature storage module is 0.01 to 3000 times the atmospheric pressure (0.001-300MPa).

Furthermore, the cryogenic storage material includes gas, liquid or solid, and a mixture of any two or three of the three phases of gas, liquid and solid. The cryogenic storage material includes a pure substance and a mixture of multiple materials.

Compared with the prior art, the present invention has the following technical advantages:

1) The present invention adopts a low-temperature storage system cooled by a DC-coupled DC regenerative refrigerator, so that the DC absorbs cold energy inside the regenerator, directly or indirectly reducing the heat leakage of the low-temperature storage module, thereby reducing the energy consumption of the low-temperature storage system and improving the efficiency of the low-temperature storage system.

2) The regenerator in the present invention can absorb a certain amount of direct current enthalpy flow, especially when the working medium is close to the critical temperature zone. Within a certain range of the direct current flow, the COP of the actual regenerator is affected by the direct current and decreases very little.

3) The method of the low-temperature storage system cooled by a coupled direct current heat recovery refrigerator of the structural form of the present invention is applicable to small systems and large systems, and is applicable to various working fluids such as liquid helium, liquid hydrogen, liquid nitrogen, liquefied methane, etc., and has broad application prospects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the mechanism of a two-stage GM refrigerator low-temperature vapor reliquefaction system according to Example 1 of the present invention;

2 is a schematic structural diagram of a cooling liquid storage system for a refrigerator internal gap structure using a coolant circulation according to Embodiment 2 of the present invention;

3 is a schematic structural diagram of a once-through cooling gas storage system coupled with a JT throttling expansion mechanism and a Stirling refrigerator structure according to Example 3 of the present invention;

FIG. 4 is a schematic structural diagram of a liquid storage system cooled by a gap structure inside a refrigerator using heat conduction according to Embodiment 4 of the present invention.

Detailed ways

The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms and other features not clearly described in this technical solution are all considered to be common technical features disclosed in the prior art.

Example 1

As shown in FIG1 , the low-temperature storage system using a DC-coupled regenerative refrigerator for cooling in this embodiment includes a two-stage GM refrigerator module and a liquid storage module;

The two-stage GM refrigerator module includes a heat recovery refrigerator unit and a direct current external circulation unit. The heat recovery refrigerator unit includes a compression device 1, a compressor low-pressure air storage tank 2, a compressor cooler and a filter device 3, a compressor high-pressure air storage tank 4, a GM compressor high- and low-pressure gas distribution valve 5, a refrigerator air inlet channel 6, a refrigerator cylinder 7, a first-stage expansion piston 11, a first-stage heat exchanger 8, a first-stage expansion piston sealing mechanism 9, a gap 10 between the first-stage expansion piston and the cylinder, a second-stage expansion piston 27, a second-stage heat exchanger 26, a first-stage cold end heat exchanger 12, a first-stage expansion chamber 13, a second-stage expansion piston sealing mechanism 14, a gap 15 between the second-stage expansion piston and the cylinder, a second-stage cold end heat exchanger 16, and a second-stage expansion chamber 17.

The direct current external circulation unit includes a direct current 28 , a partitioning heat exchanger 30 , and a direct current control valve 20 .

The liquid storage module includes a low-temperature liquid 25, a storage container outer shell 50, a storage container inner container 51, a material inlet and outlet pipeline 52, a measurement signal channel 53, a cooling screen 54, a cold-carrying channel 56 for heat exchange between a multi-layer aluminum-coated film 55 and the cooling screen, a supporting structure 57, as well as a steam booster fan 22, steam 23, a partition wall heat exchanger 30, and a cold end heat exchange component 24.

The working process of this embodiment is:

According to the above process, the system installation is completed and the gas working medium at the working pressure is filled. First, the compressor 1 is operated, and the refrigerator starts to cool down. When the temperature of the heat exchanger 16 at the cold end of the regenerator drops below the working medium liquefaction temperature, the opening of the DC control valve 20 is adjusted, and the steam booster fan 22 is started to control the DC flow and the steam gas circulation flow. Due to heat leakage, the low-temperature liquid 25 evaporates, and the steam enters the cold-carrying channel 56 for heat exchange with the cooling screen. The cold-carrying channel 56 is thermally connected with the cooling screen 54, the material inlet and outlet pipeline 52, the measurement signal channel 53 and the support structure 57, and the heat leakage caused by heat conduction and radiation is absorbed through the sensible heat of the steam. The cold-carrying channel 56 is coiled on the two-layer cooling screen 54. The temperature of the steam gradually rises from the inner layer to the outer layer until it is close to the room temperature. After being pressurized by the steam booster fan 22, it enters the partition wall heat exchanger 30, is gradually cooled by the DC 28, and is further liquefied in the cold end heat exchange component 24, returns to the inner container 51, and becomes part of the low-temperature liquid 25.

When the cooling capacity of the refrigerator is greater than the low-temperature storage heat leakage, the refrigerator can be started and stopped intermittently until a stable reliquefaction rate is obtained and the pressure in the liquid storage module is maintained.

Example 2

As shown in FIG2 , the schematic diagram of the structure of the liquid storage system of the refrigerator internal gap structure cooling using the circulating refrigerant in this embodiment includes a two-stage GM refrigerator module and a liquid storage module;

The two-stage GM refrigerator module includes a regenerative refrigerator unit and a direct current internal circulation unit. The regenerative refrigerator unit includes a compression device 1, a compressor low-pressure air storage tank 2, a compressor cooler and filter device 3, a compressor high-pressure air storage tank 4, a GM compressor high-low pressure gas distribution valve 5, a refrigerator air intake channel 6, a refrigerator cylinder 7, a first-stage expansion piston 11, a first-stage regenerator 8, a first-stage expansion piston sealing mechanism 9, a gap 10 between the first-stage expansion piston and the cylinder, a second-stage expansion piston 27, a second-stage regenerator 26, a first-stage cold end heat exchanger 12, a first-stage expansion chamber 13, a second-stage expansion piston sealing mechanism 14, a gap 15 between the second-stage expansion piston and the cylinder, a second-stage cold end heat exchanger 16, and a second-stage expansion chamber 17. The direct current internal circulation unit includes a direct current 28, an inter-stage direct current connection channel 18, a first-stage to hot end direct current connection channel 19, and a direct current control valve 20.

The liquid storage module includes a liquid storage unit and a coolant circulation unit, specifically including a cryogenic liquid 25, a storage container outer shell 50, a storage container inner container 51, a material inlet and outlet pipeline 52, a measurement signal channel 53, a cooling screen 54, a coolant channel 56 for heat exchange of the cooling screen, a support structure 57, a coolant booster fan 22, a cylinder outer wall heat exchange component 23, and a cold end heat exchange component 24.

The working process of this embodiment is:

According to the above process, the system installation is completed and the gaseous working medium at the working pressure is filled. First, the compressor 1 is operated, and the refrigerator starts to cool down. When the temperature of the heat exchanger 16 at the cold end of the regenerator drops below the working medium liquefaction temperature, the opening of the direct current control valve 20 is adjusted to control the direct current flow rate. Due to heat leakage, the low-temperature liquid 25 has a tendency to increase in temperature. The refrigerant booster fan 22 is started to control the circulation flow of the refrigerant so that the refrigerant enters the refrigerant channel 56 for heat exchange with the cooling screen. The refrigerant channel 56 is thermally connected with the cooling screen 54, the material inlet and outlet pipeline 52, the measurement signal channel 53 and the support structure 57, and the heat leakage caused by heat conduction and radiation is absorbed by the heat capacity of the refrigerant. The refrigerant channel 56 is coiled on the two-layer cooling screen 54. The temperature of the refrigerant gradually rises from the inner layer to the outer layer until it is close to the room temperature. After being pressurized by the booster fan 22, it enters the cylinder outer wall heat exchange component 23, is gradually cooled by the direct current 28, and is further cooled in the cold end heat exchange component 24, and the low-temperature liquid 25 is cooled in the inner container 51.

When the refrigeration capacity of the refrigerator is greater than the low-temperature storage heat leakage, the refrigerator can be started and stopped intermittently until a stable temperature or reliquefaction rate (for volatile refrigerants) is obtained and the pressure in the liquid storage module is maintained.

Example 3

As shown in FIG3 , a schematic diagram of the structure of a once-through cooling gas storage system coupled with a JT throttling expansion mechanism and a Stirling refrigerator structure of Example 3; including a single-stage Stirling refrigerator module, an expansion and compression module, and a gas storage module;

The single-stage Stirling refrigerator module includes a regenerative refrigerator unit and a direct current external circulation unit. The regenerative refrigerator unit includes a piston compression device 1, a compressor cooler 3, a refrigerator air inlet channel 6, a refrigerator cylinder 7, a first-stage expansion piston 11, a first-stage regenerator 8, a first-stage expansion piston sealing mechanism 9, a gap 10 between the first-stage expansion piston and the cylinder, a first-stage cold end heat exchanger 12, and a first-stage expansion chamber 13. The direct current external circulation unit includes a direct current 28, a direct current control valve 20, and a direct current control valve 59.

The expansion and compression module includes an expansion mechanism 29 , a low-pressure buffer gas reservoir 31 , a compression mechanism 32 , a compression mechanism cooler and a filter device 33 .

The gas storage module includes low-temperature gas 25, a storage container outer shell 50, a storage container inner container 51, a material inlet and outlet pipeline 52, a measurement signal channel 53, a cooling screen 54, a vacuum stacking material 55, a direct current channel 56 for heat exchange with the cooling screen, a supporting structure 57, a direct current channel 58 for heat exchange with the neck tube, and a cold end heat exchange component 24.

The working process of this embodiment is:

Complete the system installation according to the above process, and fill the gas working medium with working pressure. Preset the resistance working condition of the expansion mechanism 29 at room temperature, run the compressor 1 first, and the refrigerator starts to cool down. When the temperature of the heat exchanger 16 at the cold end of the regenerator drops to the set temperature of the gas, the direct current is divided into two paths after the pressure is reduced by the expansion mechanism 29, and the opening of the direct current control valve 20 and the direct current control valve 59 are adjusted respectively to control the circulation flow of the two direct current gases respectively.

One of the DC gas flows into the DC channel 56 for heat exchange with the cooling screen, and is thermally connected to the cooling screen 54 and the supporting structure 57, and the heat leakage caused by conduction and radiation is absorbed by the heat capacity of the DC. The DC channel 56 is wound around the single-layer cooling screen 54, and the temperature of the DC gradually rises as the cooling screen is cooled.

Another DC gas enters the DC channel 58 for heat exchange with the neck tube. The DC channel 58 is thermally connected to the cooling material inlet and outlet pipeline 52 and the measurement signal channel 53. The heat leakage caused by heat conduction is absorbed by the heat capacity of the DC. The temperature of the DC gradually rises during the cooling process until it approaches room temperature.

The two direct currents merge after cooling, and the compression mechanism 32 is started. The direct current is compressed to the original low-pressure chamber pressure to form a stable cycle. The attached buffer gas reservoir 31 is stabilized at low pressure, and the compression mechanism cooler and filter device 33 discharge the compression heat, filter and adsorb impurities.

When the cooling capacity and DC flow of the refrigerator are greater than the low-temperature storage heat leakage, the refrigerator can be started and stopped intermittently until a stable temperature is obtained and the pressure in the gas storage module is maintained.

Example 4

As shown in FIG4 , the schematic diagram of the structure of the liquid storage system using the internal gap structure of the heat-conducting refrigerator in this embodiment; it includes a two-stage GM refrigerator module and a liquid storage module;

The two-stage GM refrigerator module includes a regenerative refrigerator unit and a direct current internal circulation unit. The regenerative refrigerator unit includes a compression device 1, a compressor low-pressure air storage tank 2, a compressor cooler and filter device 3, a compressor high-pressure air storage tank 4, a GM compressor high-low pressure gas distribution valve 5, a refrigerator air intake channel 6, a refrigerator cylinder 7, a first-stage expansion piston 11, a first-stage regenerator 8, a first-stage expansion piston sealing mechanism 9, a gap 10 between the first-stage expansion piston and the cylinder, a second-stage expansion piston 27, a second-stage regenerator 26, a first-stage cold end heat exchanger 12, a first-stage expansion chamber 13, a second-stage expansion piston sealing mechanism 14, a gap 15 between the second-stage expansion piston and the cylinder, a second-stage cold end heat exchanger 16, and a second-stage expansion chamber 17. The direct current internal circulation unit includes a direct current 28, an inter-stage direct current connection channel 18, a first-stage to hot end direct current connection channel 19, and a direct current control valve 20.

The liquid storage module specifically includes a cryogenic liquid 25 , a storage container outer shell 50 , a storage container inner container 51 , a material inlet and outlet pipeline 52 , a cooling screen 54 , a support structure 57 , a heat conduction mechanism 58 and a cold end heat exchange component 24 .

The working process of this embodiment is:

According to the above process, the system is installed, and the gaseous working medium at the working pressure is filled in, and the outer wall of the refrigerator cylinder 7 is connected with the cooling screen 54, the material inlet and outlet pipeline 52, the support structure 57 and other heat leakage channels through multiple heat conduction mechanisms 58. First, the compressor 1 is operated, and the refrigerator starts to cool down. When the temperature of the heat exchanger 16 at the cold end of the regenerator drops below the set temperature of the working medium, the opening of the DC control valve 20 is adjusted to control the DC flow.

The coldness of the direct current 28 in the gap is transmitted to the cooling screen 54, the material inlet and outlet pipes 52, and the supporting structure 57 through multiple heat conduction mechanisms 58, and the heat leakage caused by heat conduction and radiation is finally absorbed by the heat capacity of the direct current 28. The temperature of the three-layer cooling screen 54 gradually increases from the inner layer to the outer layer. The cold end heat exchange component 24 exchanges heat with the cryogenic liquid 25 through convection or heat conduction to achieve cooling or reliquefaction.

When the cooling capacity of the refrigerator is greater than the low-temperature storage heat leakage, the refrigerator can be started and stopped intermittently until a stable temperature or reliquefaction rate is obtained and the pressure in the liquid storage module is maintained.

The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims (8)

1. The low-temperature storage system for cooling the direct-current coupled regenerative refrigerator is characterized by comprising a regenerative refrigeration module and a low-temperature storage module;

The regenerative refrigeration module comprises a regenerative refrigerator unit and a direct current circulation unit;

The regenerative refrigerator unit comprises a compressor device (1), a heat regenerator and a cold end heat exchanger (12) which are connected in sequence;

the direct current circulation unit comprises a divided wall type heat exchange channel, wherein a direct current (28) is led out of a heat regenerator from any position and is led into the divided wall type heat exchange channel, and the direct current is used for directly or indirectly cooling a heat leakage channel of the low-temperature storage module and then returns to the upper part of the heat regenerator, so that direct current circulation is completed;

a direct current control valve (20) is arranged in the direct current circulation unit, and the direct current flow is controlled through the direct current control valve (20);

the low-temperature storage module comprises a cold material (21), a storage container inner container and a storage container outer shell;

The low-temperature storage module further comprises a cooling screen and a cold carrying channel structure exchanging heat with the cooling screen;

The direct current is led out of the regenerator at a cold end of the regenerator or at any position between the cold end of the regenerator and the hot end of the regenerator;

The number of the leading-out positions of the direct current (28) is one or more, so that one direct current or a plurality of direct currents are formed, and the corresponding cold end heat exchanger (12) comprises one of an internal gap structure, a plurality of internal gap structures, a dividing wall type heat exchanger and a plurality of dividing wall type heat exchangers;

The direct current (28) is introduced into the heat regenerator from the dividing wall type heat exchange channel at any position between the heat regenerator hot end or the heat regenerator hot end and the heat regenerator cold end;

the partition wall type heat exchange channel after the direct current (28) is led out of the heat regenerator comprises a gap structure in the refrigerator and a partition wall type heat exchanger after the direct current is led out of the heat regenerator and the wall surface of the pressure-bearing container of the refrigerator in sequence;

The internal gap structure comprises a gap formed by an expansion piston and a cylinder, a gap formed by two or more layers of channels in a pressure-bearing pipe of the heat regenerator and a gap formed by two or more layers of channels in a pulse pipe pressure-bearing pipe;

The direct current circulation unit is also provided with an expansion mechanism and a compression mechanism, and the direct current (28) is led out of the wall surfaces of the pressure-bearing container of the regenerator and the refrigerator in sequence and then is connected with the expansion mechanism;

The expansion mechanism is a single expansion mechanism or a combination of a plurality of expansion mechanisms;

the expansion mechanism is arranged on one strand of direct current or on a plurality of strands of direct current respectively;

the position of the expansion mechanism on direct current is a cold end or any position between the cold end and the hot end;

the compression mechanism comprises a single compression mechanism or a combination of multiple compression mechanisms;

the compression mechanism is arranged on one direct current or a plurality of direct currents respectively.

2. A low temperature storage system cooled by a regenerative refrigerator coupled with direct current according to claim 1, wherein the direct current (28) is led out from the dividing wall type heat exchange channel and then led into the regenerator, or led into the low pressure assembly and then led into the regenerator, or driven by the high pressure assembly, thereby forming a cycle;

the low-pressure component is a low-pressure pipeline or a low-pressure cavity formed by arranging a one-way valve;

The high-pressure component is a high-pressure pipeline or a high-pressure cavity formed by arranging a one-way valve.

3. The low-temperature storage system for cooling a direct-current coupled regenerative refrigerator according to claim 1, wherein the structure for transmitting cold energy between the regenerative refrigerator and the low-temperature storage module is one of a pipeline type cooling medium structure, a solid heat conduction structure and a serial-parallel combination structure of pipeline transmission and solid heat conduction;

The pipeline in the pipeline type transmission cooling medium structure can cool the low-temperature storage module, and the cooling medium comprises direct current which is directly led out from the regenerative refrigerator for cooling, and gas materials and secondary refrigerant in the low-temperature storage module;

After the direct current (28) flows through the low-temperature storage module, the gas and the secondary refrigerant in the low-temperature storage module are cooled to low temperature through the dividing wall type heat exchanger outside the regenerative refrigerator or the dividing wall type heat exchange of the outer surface of the regenerative refrigerator, and are recycled.

4. The direct current coupled regenerative chiller cooled cryogenic storage system of claim 1 wherein the heat leak path is a direct current (28) cooled component, the heat leak path comprising one or more of a cooling screen, a radiant screen, a build-up material, a support structure, a material access conduit, a measurement signal path.

5. The direct current coupled regenerative refrigerator cooled cryogenic storage system of claim 1, wherein the direct current coupled regenerative refrigerator cooled cryogenic storage system adopts an insulating structure in the form of vacuum multi-layer insulation, vacuum stack insulation, and common stack insulation by reducing the heat conduction/convection/radiation;

the common stacked heat insulation material comprises foaming materials, filling materials and aerogel, and the structural form of the stacked materials in the common stacked heat insulation material comprises one of blocks, sheets, fibers, spheres and powder.

6. The direct-current coupled regenerative refrigerator cooling low-temperature storage system according to claim 1, wherein the regenerative refrigerator unit is a refrigerator which adopts a regenerator component to realize alternating storage and release of heat, and comprises a mixed structure form of multistage coupling of one or more refrigerators of a GM refrigerator, a soldier refrigerator, a stirling refrigerator, a VM refrigerator and a pulse tube refrigerator;

The pulse tube refrigerator is one of a GM pulse tube refrigerator or a Stirling pulse tube refrigerator.

7. The direct current coupled regenerative refrigerator cooled cryogenic storage system of claim 1, wherein the regenerative refrigeration module is a regenerator internal structure or a regenerator external structure;

in the built-in structure of the heat regenerator, the heat regenerator is built in the expansion piston;

in the external structure of the heat regenerator, an expansion piston and the heat regenerator are arranged in a split type;

The regenerative refrigeration module is of a single-stage structure or a multi-stage coupling structure, and the multi-stage coupling structure is one of a multi-stage thermal coupling structure, a multi-stage gas coupling structure and a thermal coupling and gas coupling mixed structure.

8. The direct current coupled regenerative chiller cooled cryogenic storage system of claim 1, wherein the average operating pressure in the regenerative refrigeration module is between 0.1 and 3000 times the atmospheric pressure and the average operating pressure in the cryogenic storage module is between 0.01 and 3000 times the atmospheric pressure.