WO2022042457A1 - 一种采用直流的回热式制冷机高效液化系统 - Google Patents

一种采用直流的回热式制冷机高效液化系统 Download PDF

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WO2022042457A1
WO2022042457A1 PCT/CN2021/113941 CN2021113941W WO2022042457A1 WO 2022042457 A1 WO2022042457 A1 WO 2022042457A1 CN 2021113941 W CN2021113941 W CN 2021113941W WO 2022042457 A1 WO2022042457 A1 WO 2022042457A1
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regenerator
heat exchanger
refrigerator
regenerative
direct current
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PCT/CN2021/113941
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English (en)
French (fr)
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曹强
栾铭凯
霍斌
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同济大学
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B40/00—Subcoolers, desuperheaters or superheaters
    • F25B40/06—Superheaters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/14—Compression machines, plants or systems characterised by the cycle used 
    • F25B2309/1408—Pulse-tube cycles with pulse tube having U-turn or L-turn type geometrical arrangements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B2600/00—Control issues
    • F25B2600/25—Control of valves

Definitions

  • the invention relates to the technical field of refrigeration, in particular to a high-efficiency liquefaction system for a regenerative refrigerator using direct current.
  • Regenerative cryogenic refrigerators have the advantages of high reliability, simple structure and high flexibility, and are widely used in low temperature technologies such as gas liquefaction and superconductivity.
  • Cao Qiang proposed a method to measure the DC quantity by using a fixed volume of gas charge to quantitatively study the influence of controllable DC on the performance of the designed multi-stage Stirling-type pulse tube refrigerator.
  • the minimum cooling temperature is reduced by 6.4K, which significantly improves the cooling performance.
  • Tsuchiya et al. introduced DC into a GM-type two-way intake pulse tube refrigerator in the liquid helium temperature zone. Under certain DC conditions, the cooling capacity was increased by 0.25W when the cooling temperature was 4.2K.
  • helium collection and liquefaction are both high.
  • liquefaction flow channel is wrapped around the outside of the regenerator tube wall for precooling, which has a large heat transfer resistance and high liquefaction efficiency.
  • the liquefaction cost per unit volume of helium is higher.
  • the purpose of the present invention is to provide a high-efficiency liquefaction system for a direct current regenerative refrigerator in order to overcome the above-mentioned defects in the prior art.
  • the high-efficiency liquefaction system for a direct current regenerative refrigerator of the present invention is The cold end and the hot end of the regenerator form a stable DC cycle, so that the DC cycle absorbs cold energy inside the regenerator, and is drawn out from the heat exchanger at the cold end of the regenerator and then enters the wall heat exchanger to exchange heat with the liquefaction module.
  • the liquefied substance is pre-cooled and returned to the hot end of the regenerator to complete the cycle.
  • the original concept of the invention is based on reducing the actual gas loss by direct current in the regenerator of the refrigeration cycle. Based on the thermodynamic analysis, the working mechanism of adding direct current to the regenerator with significant actual gas effect is revealed. The theoretical expression of the DC quantity in the regenerator and the theoretical value of the COP of the regenerator after adding DC are presented. The results show that the COP of the regenerator with direct current can be increased by more than 10 times, and even higher relative Carnot efficiency of about 80% can be achieved in some specific temperature ranges. At the same time, it is concluded that the liquefaction rate can be effectively improved by external DC in practical applications.
  • the enthalpy and entropy losses can be increased by increasing the DC in some specific temperature ranges. To further reduce, so that the system efficiency has been greatly improved.
  • the direction of negative direct current is defined as: hot end of regenerator - cold end - hot end of pulse tube; the direction of positive direct current is: hot end of pulse tube - cold end - hot end of regenerator.
  • the present invention has carried out a more innovative design.
  • the high-efficiency liquefaction system of a DC regenerative refrigerator is adopted in the present invention, including a regenerative refrigeration module and a liquefaction module;
  • the regenerative refrigeration module includes a regenerative refrigerator unit and a DC external circulation unit;
  • the regenerative refrigerator unit includes a compression device, a regenerator hot end heat exchanger, a regenerator, a regenerator cold end heat exchanger, an expansion mechanism cold end heat exchanger, an expansion mechanism, and an expansion mechanism connected in sequence. hot end heat exchanger;
  • the liquefaction module includes an air intake assembly, a partition heat exchanger, a cold end winding heat exchange pipeline and a liquid collection component that are communicated in sequence, and the cold end winding heat exchange pipeline is arranged in the cold end heat exchanger of the regenerator , for heat exchange;
  • the direct current external circulation unit is led out from the heat exchanger at the cold end of the regenerator and then enters the partition heat exchanger, uses the cooling capacity generated inside the regenerator to pre-cool the liquefied chemical, and then returns to the hot end of the regenerator , complete the DC external circulation;
  • the working fluid in the air intake assembly is first pre-cooled by the partition heat exchanger, then enters the cold end winding heat exchange pipeline to realize liquefaction, and finally flows into the liquid collection assembly.
  • the direct current external circulation unit includes a direct current circulation pipeline, and the direct current circulation pipeline is sequentially connected to the air intake assembly, the partition heat exchanger, the cold end winding heat exchange pipeline and the liquid collection component;
  • the DC circulation pipeline is also provided with a DC external circulation control component.
  • the regenerative refrigerator unit is a refrigerator that uses regenerator components to achieve alternating heat storage and release, including GM refrigerators, GM pulse tube refrigerators, Stirling refrigerators, and Sterling refrigerators. It is one of the forest-type pulse tube refrigerator and the VM refrigerator, or it can be one of several structural forms coupled.
  • the regenerative refrigeration module is a single-stage or multi-stage coupling structure
  • the multi-stage coupling structure is a multi-stage thermal coupling structure or a multi-stage gas coupling structure.
  • the regenerative refrigeration module is a multi-stage coupling structure, and the number of stages can be two-stage, three-stage, four-stage, etc.
  • the multi-stage structure can achieve a lower refrigeration temperature, and can achieve low critical temperature such as helium. Mass liquefaction.
  • the regenerative refrigeration module is a two-stage thermally coupled pulse-tube refrigerator, including a first-stage pulse-tube refrigerator, and the first-stage pulse-tube refrigerator includes first-stage pulse-tube refrigerators connected in sequence.
  • the hot-end heat exchanger of the first-stage regenerator is connected with the compression device through a pipeline, and the first-stage cold-end heat exchanger cools the middle of the second-stage regenerator through a thermal bridge.
  • the direct current external circulation unit includes a direct current circulation pipeline, and the direct current circulation pipeline is sequentially connected to the air intake assembly, the partition heat exchanger and the liquid collection component; the partition heat exchange The heat exchanger is a two-stage dividing wall heat exchanger structure; the inlet of the outer channel of the dividing wall heat exchanger is communicated with the primary dividing wall heat exchanger through a pipeline, and the outlet is communicated with the secondary dividing wall heat exchanger through a pipeline.
  • the air intake assembly and the liquid discharge assembly are removed, the liquid storage unit is connected to the hot end of the partition heat exchanger, and a certain amount of liquid is pre-installed in the liquid storage unit.
  • the endothermic gasification will be liquefied again by the low temperature refrigerator.
  • the liquid storage unit can be transformed into a constant temperature cold source.
  • the location where the direct current is introduced includes a certain position between the hot end and the cold end, and the extraction point of the direct current includes a certain position between the cold end and the hot end.
  • removing the liquefaction heat exchanger and the liquid storage unit can form a cooling effect on the relevant fluid or solid along the temperature gradient, so as to realize the pre-cooling function.
  • the average working pressure in the regenerative refrigeration module is greater than 2 times the atmospheric pressure, which is 2-100 atmospheric pressure.
  • the working pressure of the regenerative refrigeration module is generally higher than the atmospheric pressure, and the working pressure of the liquefaction module is generally the same as that of the regenerative refrigeration module.
  • the pressure in the heat exchanger is different, usually close to atmospheric pressure, and can be distributed in different flow channels through the partition heat exchanger.
  • the working pressure of the liquefaction module is close to one atmospheric pressure, and may include 0.1 to 10 times the atmospheric pressure.
  • the liquid collection assembly includes a liquid storage unit and a liquid discharge unit, wherein:
  • the outlet of the cold end winding heat exchange pipeline is communicated with the liquid storage unit
  • the liquid discharge unit communicates with the liquid storage unit through a pipeline.
  • the air intake assembly includes a high-pressure air source, a decompression unit, a buffer unit and a flow monitoring unit that are sequentially connected through pipelines;
  • the gas in the high-pressure air source passes through the high-pressure air source, the decompression unit, the buffer unit and the flow monitoring unit in sequence, and then enters the pre-cooling flow channel of the partition heat exchanger, and then enters the cold-end winding heat exchange pipeline. , is liquefied and then enters the liquid storage unit.
  • a flow control device a constant pressure gas reservoir and a one-way pressure limiting valve are also provided on the DC circulation pipeline;
  • the flow control device is a valve, a capillary, a nozzle or a resistance element formed by a porous medium
  • the one-way pressure limiting valve is a high pressure limiting valve or a low pressure limiting valve.
  • the present invention has the following technical advantages:
  • the high-efficiency liquefaction system of the regenerative refrigerator of the present invention adopts the direct current to connect the cold end and the hot end of the regenerator to form a stable direct current circulation, so that the direct current circulation absorbs the cold energy inside the After the cold end is drawn out, it exchanges heat with the liquefaction module, pre-cools the liquefied chemical, and then returns to the hot end of the regenerator to complete the cycle. It is especially suitable for compact GM refrigerators with better cooling performance.
  • the regenerator Since the regenerator is built into the cylinder, and there must be an air gap between the two, the liquefied chemical flow channel can only be wrapped around the outside of the cylinder, and There is a large air gap thermal resistance in the heat exchange of the regenerator, and the internal direct current is in close contact with the regenerative filler and the alternating current, so that there is almost no heat exchange temperature difference, which can effectively reduce the thermal resistance.
  • the regenerator in the present invention can absorb a certain amount of direct current enthalpy current, and the increase of the cold end enthalpy current caused by a suitable size direct current can be smaller than the enthalpy current absorbed by the regenerator, so the full utilization of the direct current can improve the refrigeration.
  • the liquefaction capacity of the machine especially when the working medium is close to the critical temperature region, has a maximum allowable direct current. Within this direct current range, the COP of the actual regenerator will not be affected by the direct current and will drop significantly.
  • the liquid produced by the high-efficiency liquefaction system of the direct current regenerative refrigerator of the present invention can be used as a constant temperature cold source to meet the low temperature requirement of a stable constant temperature.
  • the small cryogenic refrigerator of this structure can obviously improve the liquefaction efficiency, and the equipment is small and movable, and can be used to liquefy gases with low liquefaction temperature such as helium, hydrogen, nitrogen, etc. large-scale application.
  • FIG. 1 is a schematic structural diagram of a high-efficiency liquefaction system using a DC regenerative refrigerator according to Embodiment 1 of the present invention.
  • FIG. 2 is a schematic structural diagram of an air intake assembly according to Embodiment 1 of the present invention.
  • FIG. 3 is a schematic structural diagram of the DC external circulation unit according to Embodiment 1 of the present invention.
  • Example 4 is a schematic diagram of a high-efficiency liquefaction system of a regenerative refrigerator using a GM-type pulse tube refrigerator and a bidirectional intake valve group structure in Example 2.
  • FIG. 5 is a schematic diagram of a high-efficiency liquefaction system of a regenerative refrigerator using a two-stage GM refrigerator structure in Example 3.
  • FIG. 5 is a schematic diagram of a high-efficiency liquefaction system of a regenerative refrigerator using a two-stage GM refrigerator structure in Example 3.
  • FIG. 6 is a schematic diagram of a high-efficiency liquefaction system of a regenerative refrigerator using a two-stage thermally coupled regenerative refrigerator in Example 4.
  • the high-efficiency liquefaction system using a DC regenerative refrigerator in this embodiment includes a regenerative refrigeration module and a liquefaction module.
  • the regenerative refrigeration module includes a regenerative chiller unit and a DC external circulation unit.
  • the regenerative refrigerator unit includes a compression device 1, a compressor transfer pipe 2, a regenerator hot end heat exchanger 3, a regenerator 4, a regenerator cold end heat exchanger 5, a DC circulation line 6, and an expansion mechanism.
  • the DC external circulation unit includes a DC lead-out pipe 6 and a DC external circulation control assembly 11 .
  • the liquefaction module includes a high-pressure gas source 12 , a partition heat exchanger 13 , a liquefaction heat exchange pipeline 14 , and a liquid collection component 15 that are communicated in sequence.
  • the air intake assembly includes a high pressure air source 12 , a flow meter 16 , a pressure reducing valve 17 , and a stainless steel gas storage buffer tank 18 .
  • the DC external circulation unit of Embodiment 1 includes a one-way pressure limiting valve 19 , a constant pressure gas store 20 , and a flow control device 21 .
  • connection relationship between the components is:
  • Compression device 1 compressor transfer tube 2, regenerator hot end heat exchanger 3, regenerator 4, regenerator cold end heat exchanger 5, regenerator and expansion mechanism (exhaust or pulse tube) transfer tube 10.
  • the cold end heat exchanger 9 of the expansion mechanism (discharger or pulse tube), the expansion mechanism (discharger or pulse tube) 8, and the hot end heat exchanger 7 of the expansion mechanism (discharger or pulse tube) are connected in sequence.
  • the direct current external circulation unit of the regenerator is communicated with the cold end heat exchanger 5 of the regenerator through the direct current lead-out pipe 6, and then connected to the partition heat exchanger 13, the flow control device 21, the constant pressure gas storage 20, the one-way heat exchanger through the pipeline in turn Pressure limiting valve 19.
  • the air intake assembly includes a high-pressure gas source 12, a pressure reducing valve 17, a stainless steel gas storage buffer tank 18, and a flow meter 16, which are sequentially connected through pipelines. Liquid collection assembly 15 .
  • the structure of the GM-type pulse tube refrigerator and the two-way intake valve group of Example 2 is basically the same as that of the refrigerator shown in FIG. 1 , except that the regenerative refrigerator is a GM-type pulse tube refrigerator.
  • Refrigerator the compression device 1 of the GM pulse tube refrigerator is composed of a high pressure control valve 22, a low pressure control valve 23, a compressor 24, and a two-way intake valve group 25 is composed of two one-way valves in reverse parallel connection.
  • connection relationship between the components is:
  • the compression device 1 is connected by a compressor 24, a high-pressure control valve 22 and a low-pressure control valve 23 in sequence through pipelines.
  • Heater 5 Regenerator and Expansion Mechanism (Pulse Tube) Transmission Pipe 10, Expansion Mechanism (Pulse Tube) Cold End Heat Exchanger 9, Expansion Mechanism (Pulse Tube) 8, Expansion Mechanism (Pulse Tube) Hot End Heat Exchanger 7 is connected to the phase-modulating gas storage 26 in sequence.
  • the DC external circulation unit of the regenerator is communicated with the cold end heat exchanger 5 of the regenerator through the DC lead-out pipe 6, and then connected to the partition heat exchanger 13 and the DC external circulation control assembly 11 in turn through the pipeline.
  • the air intake assembly includes a high-pressure air source 12 and an air intake assembly structure (see FIG. 2 ) that are sequentially communicated through pipelines.
  • the secondary regenerator of the refrigerator leads out a direct current of 0.07g/s, which can increase the distributed cooling capacity from 4K to 38K from 1.42W to 13.8W, and the rate of liquefied helium gas from 0.2L/h to 1.96L/h h, the liquefaction capacity is increased by about 10 times.
  • the structure of the secondary GM refrigerator in Example 3 is basically the same as that of the refrigerator shown in FIG. 1 , except that the regenerative refrigerator is a GM refrigerator, and the compression of the GM refrigerator
  • the device 1 consists of a compressor 27, a post-stage water cooler 28, a high-pressure balance tank 29, an intake valve 30, an exhaust valve 31 and a low-pressure balance tank 32; Heater 34 , primary cylinder 35 , secondary cylinder 36 and primary partition heat exchanger 37 .
  • connection relationship between the components is:
  • Compression device 1 consists of compressor 27, post-stage water cooler 28, high-pressure balance tank 29, intake valve 30, exhaust valve 31 and low-pressure balance tank 32 connected by pipelines in sequence, compressor transmission pipe 2, first-stage hot end exchange Heater 34, primary cylinder 35, expansion mechanism (exhaust) hot end heat exchanger 7 (primary cold end heat exchanger), secondary cylinder 36 and expansion mechanism (exhaust) cold end heat exchanger 9 (two (stage cold end heat exchanger) are connected in sequence; wherein, the primary regenerator 33 is located inside the primary cylinder 35 to function as an ejector; the regenerator 4 is located inside the secondary cylinder 36 to function as an ejector; the regenerator is DC The external circulation unit is communicated with the cold end heat exchanger 5 of the regenerator through the direct current lead-out pipe 6, and then connected to the partition wall heat exchanger 13, the first-stage partition wall heat exchanger 37, the direct current external circulation control assembly 11 and the low pressure through the pipeline in turn.
  • the balance tank 32; the air intake assembly includes the high-pressure air source 12, the air intake assembly structure (see FIG. 2), and the first-stage partition heat exchanger 37, which are sequentially communicated through pipelines.
  • the working medium enters the partition wall heat exchanger 13 and passes through The liquefied chemical flow channel 14 enters the liquid collection assembly 15 .
  • the structure of the two-stage thermally coupled regenerative refrigerator in Example 4 is basically the same as that of the refrigerator shown in FIG. 1 , except that the regenerative refrigerator is a two-stage thermally coupled refrigerator.
  • a first-stage hot-end heat exchanger 38, a first-stage expansion mechanism (exhaust or pulse tube) 39, and a first-stage expansion mechanism (exhaust or pulse tube) cold-end heat exchanger are added 40.
  • connection relationship between the components is:
  • the hot end heat exchanger 41 of the primary regenerator is connected with the regenerative refrigerator compression device 1 through pipelines, and the primary cold end heat exchanger 43 cools the middle of the regenerator 4 through a thermal bridge 45 .
  • a first-stage dividing wall heat exchanger 46 is added, and the cold end heat exchanger 5 of the regenerator is connected to the dividing wall heat exchanger 13 , the first-stage dividing wall heat exchanger 46 and the DC external circulation control assembly 11 in sequence through pipelines.

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Abstract

本发明涉及一种采用直流的回热式制冷机高效液化系统，包括回热式制冷模块和液化模块；所述回热式制冷模块包括回热式制冷机单元以及直流外部循环单元；所述回热式制冷机单元包括依次连接的压缩装置、回热器热端换热器、回热器、回热器冷端换热器、膨胀机构冷端换热器、膨胀机构、膨胀机构热端换热器。与现有技术相比，本发明换热热阻更小，尤其适配于制冷性能较优的紧凑型GM制冷机，由于回热器内置于气缸中，且二者必然存在气隙，只能将液化工质流道缠绕在气缸外侧，与回热器换热存在较大的气隙热阻，内部引出直流与回热填料和交变流紧密接触，由此做到几乎无换热温差，可有效降低热阻。

Description

一种采用直流的回热式制冷机高效液化系统 技术领域
本发明涉及制冷技术领域，尤其是涉及一种采用直流的回热式制冷机高效液化系统。
背景技术
回热式低温制冷机具有可靠性高、结构简单、灵活性高等优点，在气体液化、超导等低温技术中得到广泛应用。
理想的回热式低温制冷机如脉管制冷机在运行中并不存在直流。然而随着双向进气结构的引入形成了一个由双向进气阀，回热器和脉管构成的闭合回路。这种回路引发了直流流动，直流由于最早由Gedeon正式提出并进行了理论论证而也被称作Gedeon直流。最初认为直流现象对制冷机的稳定性、制冷效率产生严重影响，自上世纪九十年代以来一直备受关注，具有重要研究意义。然而之后一系列的理论和实验表明，一定流量的正向、负向直流都具有提高脉管制冷机制冷性能的潜力。1997年，陈国邦等人在一台两级脉管制冷机中引入了一股负向直流，降低了脉管中部的温度，增强了调相作用，提高了回热器性能，减少了损失。1998年，王超通过数值模拟和实验结合的方法，发现一定负向直流可以显著地提高G-M制冷机的制冷性能。同年，王超得出了一台单级双向进气型脉管制冷机性能提升的可控直流的范围区间：-0.13％-+0.016％(可控直流量与回热器中交流量的比值)。2012年，曹强在提出一种利用固定体积充气来测定直流量的方法，定量研究可控直流对其设计的多级斯特林型脉管制冷机性能的影响。在20K温区使最低制冷温度降低达6.4K，显著提升了制冷性能。2014年，Tsuchiya等人在一台液氦温区GM型双向进气的脉管制冷机中引入直流，一定直流量的工况下制冷温度为4.2K时制冷量提高了0.25W。
氦气收集成本和液化成本均较高，市面上也存在一些小型可移动式的氦液化装置，通常将液化流道缠绕在回热器管壁外侧预冷，换热热阻较大，液化效率较低，单位体积氦气的液化成本较高。
发明内容
本发明的目的就是为了克服上述现有技术存在的缺陷而提供一种采用直流的回热式制冷机高效液化系统，本发明的采用直流的回热式制冷机高效液化系统，通过管路连通回热器冷端和热端，形成稳定的直流循环，使得直流循环在回热器内部吸收冷量，并从回热器冷端换热器引出后进入间壁式换热器与液化模块换热，预冷液化工质，再回到回热器热端，完成循环。
本发明的构思原始基础为，通过制冷循环的回热器中的直流减少实际气体损失，在热力学分析的基础上，揭示了在实际气体效应显著的回热器中加入直流的工作机理，得出了回热器中直流量的理论表达式及加入直流后回热器COP的理论值。结果表明，有直流的回热器的COP可以提高10倍以上，在某些特定温度范围内甚至可以达到更高的约80％的相对卡诺效率。同时得出，在实际应用中可用外部直流有效改善液化速率，虽然这种方法不能消除所有实际气体相关的“固有”热损失，但是焓损失和熵损失可以通过在某些特定温度范围内增加直流来进一步降低，使系统效率有较大提升。注意到，负向直流的方向定义为：回热器热端-冷端-脉管热端；正向直流的方向为：脉管热端—冷端—回热器热端。
基于上述原始构思基础，本发明进行了更具创新的设计，本发明中采用直流的回热式制冷机高效液化系统，包括回热式制冷模块和液化模块；
所述回热式制冷模块包括回热式制冷机单元以及直流外部循环单元；
所述回热式制冷机单元包括依次连接的压缩装置、回热器热端换热器、回热器、回热器冷端换热器、膨胀机构冷端换热器、膨胀机构、膨胀机构热端换热器；
所述液化模块包括依次连通的进气组件、间壁式换热器、冷端缠绕换热管路以及液体收集组件，所述冷端缠绕换热管路设于回热器冷端换热器中，进行换热；
所述直流外部循环单元从回热器冷端换热器引出后进入所述间壁式换热器，利用回热器内部产生的冷量预冷液化工质，之后再回到回热器热端，完成直流外部循环；
所述进气组件中的工质首先通过所述间壁式换热器进行预冷，之后进入冷端缠绕换热管路实现液化，最后流入液体收集组件。
进一步地，所述直流外部循环单元包括直流循环管路，所述直流循环管路依次连接进气组件、间壁式换热器、冷端缠绕换热管路以及液体收集组件；
所述直流循环管路上还设有直流外部循环控制组件。
进一步地，所述回热式制冷机单元为采用回热器部件实现热量的交变式储存与 释放的制冷机，包括GM制冷机、GM型脉管制冷机、斯特林制冷机、斯特林型脉管制冷机、VM制冷机中的一种，也可以是几种结构形式耦合的一种。
进一步地，所述回热式制冷模块为单级或多级耦合结构；
所述多级耦合结构为多级热耦合结构或多级气耦合结构。
进一步地，所述回热式制冷模块为多级耦合结构，级数可以是两级、三级、四级等，多级结构可达到较低的制冷温度，可实现氦等临界温度低的工质液化。
作为本发明的一种实施方式，所述回热式制冷模块为两级热耦合脉管制冷机，包括第一级脉管制冷机，所述第一级脉管制冷机包括依次连接的第一级回热器热端换热器、第一级回热器、第一级冷端换热器、第一级脉管、第一级脉管热端换热器、第一级调相机构，所述第一级回热器热端换热器与所述压缩装置通过管路连接，所述第一级冷端换热器通过热桥冷却二级回热器的中部。
作为本发明的另一种实施方式，所述直流外部循环单元包括直流循环管路，所述直流循环管路依次连接进气组件、间壁式换热器以及液体收集组件；所述间壁式换热器为两级间壁式换热器结构；所述间壁式换热器的外通道的入口通过管路与一级间壁式换热器连通，出口通过管路与二级间壁式换热器连通。
作为本发明的另一种实施方式，去掉进气组件和排液组件，将储液单元与间壁式换热器热端相连，储液单元中预装一定量的液体，当储液单元中液体吸热气化，将被低温制冷机再次液化，只要取冷的功率低于液化功率，可将储液单元改造为恒温冷源。
作为本发明的另一种实施方式，引入直流的位置包括热端至冷端之间的某个部位，引出直流引出点包括冷端到热端之间的某个部位。
作为本发明的另一种实施方式，去掉液化换热器及储液单元，可形成对相关流体或固体沿温度梯度的冷却作用，实现预冷功能。
进一步地，所述回热式制冷模块中的平均工作压力大于2倍的大气压，为2-100大气压，回热式制冷模块工作压力一般高于大气压，液化模块工作压力一般与回热式制冷模块中的压力不同，常为接近于大气压，可通过间壁式换热器分布在不同流道中。
所述液化模块的工作压力接近于一个大气压，可包括0.1至10倍的大气压。
进一步地，为了便于制造和安装，液体收集组件包括储液单元和排液单元，其中：
所述冷端缠绕换热管路的出口与储液单元连通；
所述排液单元通过管路与储液单元连通。
进一步地，所述进气组件包括依次通过管路连接的高压气源、减压单元、缓冲单元和流量监测单元；
所述高压气源内的气体依次通过高压气源、减压单元、缓冲单元和流量监测单元后进入所述间壁式换热器的预冷流道，之后进入所述冷端缠绕换热管路，被液化后进入储液单元。
进一步地，所述的直流循环管路上还设有流量控制装置、恒压气库和单向限压阀；
所述流量控制装置为阀门、毛细管、喷嘴或多孔介质形成的阻力元件；
所述单向限压阀是高压限压阀或低压限压阀。
与现有技术相比，本发明具有以下技术优势：
1)本发明的采用直流的回热式制冷机高效液化系统，通过管路连通回热器冷端和热端，形成稳定的直流循环，使得直流循环在回热器内部吸收冷量，并从冷端引出后与液化模块换热，预冷液化工质，再回到回热器热端，完成循环，和传统的液化工质流道通过缠绕回热器外壁预冷相比，换热热阻更小，尤其适配于制冷性能较优的紧凑型GM制冷机，由于回热器内置于气缸中，且二者必然存在气隙，只能将液化工质流道缠绕在气缸外侧，与回热器换热存在较大的气隙热阻，内部引出直流与回热填料和交变流紧密接触，由此做到几乎无换热温差，可有效降低热阻。
2)本发明中的回热器可以吸收一定量直流的焓流，且合适大小的直流造成冷端焓流的增大可小于其吸收的焓流，因此对引出直流的充分利用，可提高制冷机液化能力，特别是在工质接近临界温区，存在一个最大允许直流量，在该直流范围内，实际回热器的COP不会受直流影响而明显下降。
3)本发明的采用直流的回热式制冷机高效液化系统产生的液体可作为恒温冷源，满足稳定恒温的低温需求。
4)该结构形式的小型低温制冷机能明显提高液化效率，且设备较小、可移动，能用来液化氦气、氢气、氮气等液化温度较低的气体，促进移动式小型制冷机液化装置的大规模应用。
附图说明
图1为本发明实施例1的采用直流的回热式制冷机高效液化系统的结构示意图。
图2为本发明实施例1的进气组件的结构示意图。
图3为本发明实施例1的直流外部循环单元的结构示意图。
图4是实施例2中采用GM型脉管制冷机和双向进气阀组结构的回热式制冷机高效液化系统示意图。
图5是实施例3中采用二级GM制冷机结构的回热式制冷机高效液化系统示意图。
图6是实施例4中采用两级热耦合回热式制冷机的回热式制冷机高效液化系统示意图。
图中：1、压缩装置；2、压缩机传输管；3、回热器热端换热器；4、回热器；5、回热器冷端换热器；6、直流引出管；7、膨胀机构热端换热器；8、膨胀机构；9、膨胀机构冷端换热器；10、回热器与膨胀机构传输管；11、直流外部循环控制组件；12、高压气源；13、间壁式换热器；14、液化管路；15、储液单元；16、流量计；17、减压阀；18、不锈钢气库缓冲罐；19、单向限压阀；20、恒压气库；21、流量控制装置；22、高压控制阀；23、低压控制阀；24、压缩机；25、双向进气阀组；26、调相气库；27、压缩机；28、级后水冷器；29、高压平衡罐；30、进气阀；31、排气阀；32、低压平衡罐；33、一级回热器；34、一级热端器；35、一级气缸；36、二级气缸、37、一级间壁式换热器；38、一级热端换热器；39、一级膨胀机构；40、一级膨胀机构冷端换热器；41、一级回热器热端换热器；42、一级回热器；43、一级回热器侧冷端换热器；44、一级回热器与膨胀机构传输管；45、热桥；46、一级间壁式换热器。
具体实施方式
下面结合附图和具体实施例对本发明进行详细说明。
实施例1
如图1所示，本实施例的采用直流的回热式制冷机高效液化系统包括回热式制冷模块和液化模块。
回热式制冷模块包括回热式制冷机单元和直流外部循环单元。回热式制冷机单元包括压缩装置1、压缩机传输管2、回热器热端换热器3、回热器4、回热器冷 端换热器5、直流循环管路6、膨胀机构(排出器或脉管)热端换热器7、膨胀机构(排出器或脉管)8、膨胀机构(排出器或脉管)冷端换热器9、回热器与膨胀机构(排出器或脉管)传输管10。直流外部循环单元包括直流引出管6、直流外部循环控制组件11。
液化模块包括依次连通的高压气源12、间壁式换热器13、液化换热管路14、液体收集组件15。
如图2所示，进气组件包括高压气源12、流量计16、减压阀17、不锈钢气库缓冲罐18。
如图3所示，实施例1的直流外部循环单元包括单向限压阀19、恒压气库20、流量控制装置21。
各部件之间的连接关系为：
压缩装置1、压缩机传输管2、回热器热端换热器3、回热器4、回热器冷端换热器5、回热器与膨胀机构(排出器或脉管)传输管10、膨胀机构(排出器或脉管)冷端换热器9、膨胀机构(排出器或脉管)8、膨胀机构(排出器或脉管)热端换热器7依次连接。
回热器直流外部循环单元通过直流引出管6与回热器冷端换热器5连通，再通过管路依次连通间壁式换热器13、流量控制装置21、恒压气库20、单向限压阀19。
进气组件包括通过管路依次连通的高压气源12、减压阀17、不锈钢气库缓冲罐18、流量计16，工质进入间壁式换热器13液化后通过液化工质流道14进入液体收集组件15。
本实施例的工作过程为：
按上述流程完成系统安装，置换3～4次，最终回热式制冷模块内充入工作压力的气体工质。先打开压缩机的电源，回热式制冷机开始降温，当回热器冷端换热器5温度降低至工质液化转变温度以下，打开单向限压阀19和高压气源12的阀门，逐渐调大减压阀17的压力，冷端换热器温度升高，温度升至液化工质的液化转变温度时停止调节减压阀17，即可获得最大液化量。
实施例2
如图4所示，实施例2的GM型脉管制冷机和双向进气阀组，结构与图1 所示制冷机结构基本相同，其不同之处在于回热式制冷机为GM型脉管制冷机，GM型脉管制冷机的压缩装置1由高压控制阀22、低压控制阀23、压缩机24组成，双向进气阀组25由两个单向阀反向并联组成。
各部件之间的连接关系为：
压缩装置1由压缩机24、高压控制阀22和低压控制阀23依次通过管路连接，压缩机传输管2、回热器热端换热器3、回热器4、回热器冷端换热器5、回热器与膨胀机构(脉管)传输管10、膨胀机构(脉管)冷端换热器9、膨胀机构(脉管)8、膨胀机构(脉管)热端换热器7和调相气库26依次连接。
回热器直流外部循环单元通过直流引出管6与回热器冷端换热器5连通，再通过管路依次连通间壁式换热器13、直流外部循环控制组件11。
进气组件包括通过管路依次连通的高压气源12、进气组件结构(参见图2)，工质进入间壁式换热器13液化后通过液化工质流道14进入液体收集组件15。
本实施例的工作过程为：
按上述流程完成系统安装，置换3～4次，最终回热式制冷模块内充入工作压力的气体工质。先打开高压控制阀22和低压控制阀23的控制电源，使其按脉管制冷机工作频率运行，再打开压缩机24的电源，脉管制冷机开始降温，当回热式制冷模块温度降至工质临界点温度时，当回热器冷端换热器5温度降低至工质转变温度以下，打开单向限压阀19和高压气源12的阀门，逐渐调大减压阀17的压力，冷端换热器温度升高，温度升至液化工质的液化转变温度停止调节减压阀，即可获得最大液化量。
运用REGEN3.3模拟一台实际二级GM型回热器中引出直流对液化性能的提升，其中，该制冷机第二级的冷、热端温度分别为4K和38K，工作压力为1.4MPa(二级GM型回热器详细参数见论文Wang C.Helium liquefaction with a 4 K pulse tube cryocooler.Cryogenics.2001；41:491-496.)。制冷机二级回热器引出0.07g/s的直流，可使分布在4K到38K的分布式制冷量由1.42W增加至13.8W，液化氦气的速率由0.2L/h增加至1.96L/h，液化能力提升约10倍。
实施例3
如图5所示，实施例3的二级GM制冷机结构示意图，结构与图1所示制冷机结构基本相同，其不同之处在于回热式制冷机为GM制冷机，GM制冷机 的压缩装置1由压缩机27、级后水冷器28、高压平衡罐29、进气阀30、排气阀31和低压平衡罐32组成；此外，需要增加一级回热器33、一级热端换热器34、一级气缸35、二级气缸36和一级间壁式换热器37。
各部件之间的连接关系为：
压缩装置1由压缩机27、级后水冷器28、高压平衡罐29、进气阀30、排气阀31和低压平衡罐32依次通过管路连接，压缩机传输管2、一级热端换热器34、一级气缸35、膨胀机构(排出器)热端换热器7(一级冷端换热器)、二级气缸36和膨胀机构(排出器)冷端换热器9(二级冷端换热器)依次连接；其中，一级回热器33位于一级气缸35内部充当排出器的功能；回热器4位于二级气缸36内部充当排出器的功能；回热器直流外部循环单元通过直流引出管6与回热器冷端换热器5连通，再通过管路依次连通间壁式换热器13、一级间壁式换热器37、直流外部循环控制组件11和低压平衡罐32；进气组件包括通过管路依次连通的高压气源12、进气组件结构(参见图2)、一级间壁式换热器37，工质进入间壁式换热器13液化后通过液化工质流道14进入液体收集组件15。
本实施例的工作过程为：
按上述流程完成系统安装，置换3～4次，最终回热式制冷模块内充入工作压力的气体工质。先打开进气阀30和排气阀31的控制电源，使其按二级GM制冷机工作频率运行，然后打开级后水冷器28的水源，再打开压缩机27的电源，GM制冷机开始降温，当回热式制冷模块温度降至工质临界点温度时，当回热器冷端换热器5温度降低至工质液化转变温度以下，打开单向限压阀19和高压气源12的阀门，逐渐调大减压阀17的压力，冷端换热器温度升高，温度升至液化工质的液化转变温度停止调节减压阀，即可获得最大液化量。
实施例4
如图6所示，实施例4的两级热耦合回热式制冷机，结构与图1所示制冷机结构基本相同，其不同之处在于，回热式制冷机为两级热耦合制冷机，在原回热式制冷机基础上，增加了一级热端换热器38、一级膨胀机构(排出器或脉管)39、一级膨胀机构(排出器或脉管)冷端换热器40、一级回热器热端换热器41、一级回热器42、一级回热器侧冷端换热器43、一级回热器与膨胀机构(排出器或脉管)传输管44、热桥45、一级间壁式换热器46。
各部件之间的连接关系为：
一级膨胀机构(排出器或脉管)热端换热器38、一级膨胀机构(排出器或脉管)39、一级膨胀机构(排出器或脉管)冷端换热器40、一级回热器与膨胀机构(排出器或脉管)传输管44、一级回热器侧冷端换热器43、一级回热器42、一级回热器热端换热器41依次连接。一级回热器热端换热器41与回热式制冷机压缩装置1通过管路连接，一级冷端换热器43通过热桥45冷却回热器4中部。增加了一级间壁式换热器46，回热器冷端换热器5通过管路与间壁式换热器13、一级间壁式换热器46和直流外部循环控制组件11依次相连。
本实施例的工作过程为：
安装完系统后，置换3～4次，最终充入工作压力气体。先打开压缩机的电源，回热式制冷机开始降温，当回热器冷端换热器5温度降低至工质转变温度以下，打开单向限压阀19和高压气源12的阀门，逐渐调大减压阀17的压力，冷端换热器温度升高，温度升至液化工质的液化转变温度停止调节减压阀，即可获得最大液化量。
上述的对实施例的描述是为便于该技术领域的普通技术人员能理解和使用发明。熟悉本领域技术的人员显然可以容易地对这些实施例做出各种修改，并把在此说明的一般原理应用到其他实施例中而不必经过创造性的劳动。因此，本发明不限于上述实施例，本领域技术人员根据本发明的揭示，不脱离本发明范畴所做出的改进和修改都应该在本发明的保护范围之内。

Claims (4)

  1. 一种采用直流的回热式制冷机高效液化系统，其特征在于，包括回热式制冷模块和液化模块；
    所述回热式制冷模块包括回热式制冷机单元以及直流外部循环单元；
    所述回热式制冷机单元包括依次连接的压缩装置(1)、回热器热端换热器(3)、回热器(4)、回热器冷端换热器(5)、膨胀机构(8)；
    所述液化模块包括依次连通的进气组件、间壁式换热器、冷端缠绕换热管路以及液体收集组件；
    所述直流外部循环单元，直流从回热器冷端换热器(5)引出后进入所述间壁式换热器，利用回热器内部产生的冷量预冷进气组件中的工质，之后再回到回热器热端，完成直流外部循环；
    所述进气组件中的工质首先通过所述间壁式换热器进行预冷，之后进入冷端缠绕换热管路实现液化，最后流入液体收集组件。
  2. 根据权利要求1所述的一种采用直流的回热式制冷机高效液化系统，其特征在于，所述直流外部循环单元包括直流循环管路(6)，所述直流循环管路(6)依次连接进气组件、间壁式换热器、冷端缠绕换热管路以及液体收集组件。
  3. 根据权利要求1所述的一种采用直流的回热式制冷机高效液化系统，其特征在于，所述回热式制冷机单元为GM制冷机、GM型脉管制冷机、斯特林制冷机、斯特林型脉管制冷机、VM制冷机中的一种。
  4. 根据权利要求3所述的一种采用直流的回热式制冷机高效液化系统，其特征在于，所述回热式制冷模块为单级或多级耦合结构；
    所述多级耦合结构为多级热耦合结构或多级气耦合结构。
PCT/CN2021/113941 2020-08-25 2021-08-23 一种采用直流的回热式制冷机高效液化系统 WO2022042457A1 (zh)

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CN112097422A (zh) * 2020-08-25 2020-12-18 同济大学 一种采用直流的回热式制冷机高效液化系统
CN114791203B (zh) * 2022-05-23 2024-02-20 浙江大学 一种采用回热式制冷机冷端与热端直流的氢、氦节流液化系统

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