CN103047788A - J-T throttling refrigeration circulating system driven by low-temperature linear compressor - Google Patents

Abstract

The invention discloses a J-T throttling refrigeration circulating system driven by a low-temperature linear compressor. The J-T throttling refrigeration circulating system comprises a refrigeration unit and a precooling unit, wherein the refrigeration unit comprises the one-stage low-temperature linear compressor, a heat exchanger before throttling, a throttling valve and an evaporator, the precooling unit comprises a one-stage precooling heat exchanger and a precooling mechanism, the outlet of the one-stage low-temperature linear compressor is communicated with a high-temperature side pipeline of the one-stage precooling heat exchanger, a high-temperature side pipeline of the heat exchanger before throttling, the throttling valve, a low-temperature side pipeline of the heat exchanger before throttling and the inlet of the compressor sequentially through pipelines to form a circulating loop, and the outlet of the precooling mechanism is communicated with a low-temperature side pipeline of the one-stage precooling heat exchanger, a surface coil pipe of the one-stage low-temperature linear compressor and the inlet of the precooling mechanism sequentially through pipelines to form a circulating precooling loop. According to the refrigeration circulating system, the compressor which works at the low temperature is used, pressure losses of a refrigerating medium, which are caused by the reverse-flow heat exchanger, are reduced, the pressure ratio of two ends of the throttling valve is increased, and the J-T throttling refrigeration performance is improved.

Description

J-T Throttle Refrigeration Cycle System Driven by Low Temperature Linear Compressor

technical field

The invention relates to the technical field of refrigeration, in particular to a J-T throttling refrigeration cycle system driven by a low-temperature linear compressor.

Background technique

With the development of space detection technology, more and more detectors work in the 4K and mK temperature zone, and the mK temperature zone must provide pre-cooling in the 4K temperature zone, so the 4K temperature zone is an extremely important in space detection. The temperature zone has always been the focus and difficulty of scientific research.

The refrigeration methods in the space liquid helium temperature zone mainly include liquid helium (or superfluid helium) Dewar technology and mechanical refrigeration technology. Among them, the liquid helium Dewar refrigeration technology uses the evaporation and heat absorption of liquid helium or superfluid helium stored in a high-vacuum multi-layer adiabatic storage tank to achieve the cooling effect. This method can obtain a relatively stable temperature. In the field of early aerospace exploration It has a wide range of applications, and the technology is relatively mature, but it has the disadvantages of large size, heavy weight, complex insulation system, high launch cost, and limited service life by the amount of working fluid stored. With the progress and development of mechanical refrigeration technology, especially the application of leaf spring and gap seal technology, the long life problem that Dewar technology has never been able to overcome has been completely solved, making mechanical refrigeration technology such as Stirling refrigerator and pulse Tube refrigerators have developed rapidly in the aerospace field in the past 20 years and have occupied a considerable share. However, in the temperature range below 15K, helium seriously deviates from the ideal gas properties, and the volume specific heat capacity of the regenerative material drops sharply. As a result, Stirling refrigerators and Stirling-type pulse tube refrigerators that have been widely used in space are cooled in the liquid helium temperature range. less efficient. In actual space applications, it is often desired that the compressor unit be as close as possible to the heat dissipation unit for heat dissipation, and as far away from the cooled detector device as possible to reduce heat dissipation, mechanical vibration and electromagnetic interference caused by the compressor. However, the distance between the cold end and the hot end of the regenerative cryogenic refrigerator is relatively close, and it is difficult to realize the requirement of separating the compressor and the cold end, thus limiting its application in space missions.

The Joule-Thomson cooler (Joule-Thomson Cooler, hereinafter referred to as J-T throttling refrigerator) uses the Joule-Thomson throttling effect caused by the significant non-ideal characteristics of helium when the temperature is lower than 15K to obtain Refrigeration, high efficiency. Moreover, the J-T refrigerator has no moving parts at the cold end, the working medium flows directly, and the cold head can be freely designed according to the required cooling structure. A series of advantages brought about by the J-T refrigerator have become the mainstream of the space liquid helium temperature zone.

J-T refrigerator compressor unit can be divided into two types: non-mechanical compressor and mechanical compressor. The former mainly uses adsorption compressors, which is one of the hot spots in the research of J-T refrigerators at present. It has the characteristics of no moving parts, small mechanical vibration and electromagnetic interference, but the efficiency of adsorption compressors is generally low, and the structure of the compressor system is relatively complicated. The latter works at room temperature. Although the compressor unit inevitably has certain mechanical vibration and electromagnetic interference, the mechanical compressor technology is relatively mature, the system structure is simple, and the efficiency is relatively high. As for the long life, low vibration and oil-free requirements in the space liquid helium temperature zone, currently only linear compressors can meet the requirements of mechanical compressors. Therefore, the linear compressor is the main driving type for the actual space application of the J-T refrigerator at present. Most of the existing J-T refrigerators have the technical problem of low refrigeration performance.

Contents of the invention

The invention provides a J-T throttling refrigerating cycle system driven by a low-temperature linear compressor. The refrigerating cycle system uses a compressor working at a low temperature, which reduces the pressure loss of the refrigerant caused by the counterflow heat exchanger. When the inlet and outlet pressure ratios are the same, the pressure ratio at both ends of the throttle valve is increased, and the J-T throttling refrigeration performance is improved.

A J-T throttling refrigeration cycle system driven by a low-temperature linear compressor, comprising a refrigeration unit and a pre-cooling unit, the refrigeration unit comprising a first-stage low-temperature linear compressor, a heat exchanger before throttling, a throttle valve and an evaporator; The pre-cooling unit described above includes a primary pre-cooling heat exchanger and a pre-cooling mechanism; according to the flow direction of the refrigerant, the outlet of the primary low-temperature linear compressor is sequentially connected with the high-temperature side pipeline of the primary pre-cooling heat exchanger through pipelines, The high-temperature side pipeline of the heat exchanger before throttling, the throttle valve and the inlet of the evaporator are connected, and the outlet of the evaporator is connected with the low-temperature side pipeline of the heat exchanger before throttling and the inlet of the compressor through the pipeline to form a circulation loop; according to The flow direction of the pre-cooling agent, the outlet of the pre-cooling mechanism is connected with the low-temperature side pipeline of the first-stage pre-cooling heat exchanger, the surface coil of the first-stage low-temperature linear compressor, and the inlet of the pre-cooling mechanism through pipelines to form a circulating pre-cooling circuit .

If the compressor works at low temperature, its coil resistance will be greatly reduced, and the Joule heat generated by itself will also be reduced accordingly. Small. For the J-T throttling refrigerator in the cryogenic temperature zone compressed at room temperature, multi-stage counterflow heat exchangers are often required to recover cooling capacity. If the compressor directly compresses at low temperature, the number of counterflow heat exchangers can be reduced, thus reducing The pressure drop caused by multiple heat exchangers makes the pressure before throttling closer to the discharge pressure of the compressor, and the pressure after throttling is closer to the suction pressure of the compressor. The temperature drop caused by throttling is greater, and lower temperature can be obtained Cooling temperature or greater cooling capacity (better cooling performance). Its working medium can be helium, hydrogen, neon (rare gases are very expensive and generally not used), nitrogen, etc. The low temperature environment of the compressor depends on its working medium and refrigeration temperature requirements.

In order to further improve refrigeration performance, preferably, the first-stage low-temperature linear compressor is a superconducting linear compressor. The superconducting linear compressor is a linear compressor using superconducting coils working at low temperature. It not only has the advantages of ordinary linear compressors, but also shows better performance at low temperatures. The resistance of the linear compressor using the superconducting motor is almost zero when it is lower than the temperature of its coil material, thus eliminating the copper loss of the superconducting linear compressor, thereby eliminating the Joule heat generated by the corresponding coil. Therefore, when the superconducting linear compressor works below the critical temperature of its coil material, the heat load generated by itself is only the compression heat generated by the compressed working fluid, that is to say, the cooling capacity required to maintain the low temperature environment is small. Therefore, the J-T throttling refrigeration cycle in the liquid helium temperature zone using the superconducting linear compressor can more efficiently obtain the refrigeration performance in the liquid helium temperature zone, and at the same time has the advantages of compact structure, long life, and high reliability.

In actual use, as a preference, the compressor can adopt multi-stage compression. For example, when two-stage compression is used, the distance between the outlet of the high-temperature side pipeline of the first-stage precooling heat exchanger and the inlet of the high-temperature side pipeline of the heat exchanger before throttling There are also two-stage low-temperature linear compressors and two-stage pre-cooling heat exchangers on the pipeline between; The outlet of the compressor communicates with the inlet of the high temperature side pipeline of the heat exchanger before throttling through the high temperature side pipeline of the secondary precooling heat exchanger; the low temperature side pipeline inlet of the secondary precooling heat exchanger is simultaneously connected with the The outlet of the pre-cooling mechanism is connected, and the outlet is connected with the surface coil inlet of the two-stage low-temperature linear compressor; the surface coil outlet of the two-stage low-temperature linear compressor is simultaneously connected with the inlet of the pre-cooling mechanism through a pipeline. When using two-stage compression, the working fluid is cooled to the suction temperature of the first-stage low-temperature linear compressor at the outlet of the first-stage low-temperature linear compressor, and then enters the second-stage low-temperature linear compressor, which can reduce the second-stage compression. The heat can also reduce the total input work and improve cycle efficiency. As a further preference, the two-stage low-temperature linear compressor is a superconducting linear compressor.

In the refrigeration unit, a linear compressor can also be added according to actual needs. As a preference, a linear compressor is also arranged on the pipeline between the low-temperature side pipeline outlet of the heat exchanger before throttling and the inlet of the first-stage low-temperature linear compressor. , a primary heat exchanger, a high-temperature pre-cooling heat exchanger, and a secondary heat exchanger; according to the flow direction of the refrigerant, the outlet of the low-temperature side pipeline of the heat exchanger before throttling passes through the pipeline in sequence with the secondary heat exchanger The low-temperature side pipeline and the low-temperature side pipeline of the first-stage heat exchanger are connected with the inlet of the linear compressor, and the outlet of the linear compressor is connected with the high-temperature side pipeline of the first-stage heat exchanger and the high-temperature pre-cooling heat exchanger through the pipeline in turn. And the high-temperature side pipeline of the secondary heat exchanger communicates with the inlet of the primary low-temperature linear compressor.

The pre-cooling mechanism can be selected according to the temperature at which the low-temperature linear compressor needs to work, and a refrigeration mechanism with different refrigerants can be selected. For example, if the compressor needs to work at 20K, then generally liquid hydrogen is used as the low-temperature fluid for cooling the compressor, and it can also be used. If it is helium, the corresponding refrigeration mechanism can be a hydrogen adsorption refrigeration mechanism or a J-T throttling refrigeration mechanism using hydrogen as a working medium, or a regenerative refrigeration mechanism using helium as a working medium (GM refrigerator, Stirling refrigerator , GM pulse tube refrigerator, Stirling pulse tube refrigerator or Stirling/pulse tube composite refrigerator). If the compressor works in a temperature range of about 80K, the refrigeration mechanism can adopt a J-T throttling refrigeration mechanism using nitrogen as a working medium, or a regenerative refrigeration mechanism using helium as a working medium.

In order to obtain a refrigerating temperature zone of 4K, preferably, the refrigerant is helium, and the pre-cooling mechanism is a pre-cooling mechanism that can provide a cold source with a temperature below 20K; the coil of the superconducting linear compressor is A superconducting material with a critical temperature higher than 20K; the refrigerant at the refrigerant outlet of the pre-cooling heat exchanger needs to be pre-cooled to a temperature below 20K.

Compared with the prior art, the beneficial effects of the present invention are reflected in:

(1) The J-T throttling refrigeration cycle system driven by the low-temperature linear compressor of the present invention has strong adjustability, and can adopt the form of single-stage or multi-stage superconducting linear compressor to compress below the critical temperature of the coil material, or can adopt The linear compressor compresses in one stage at room temperature, and the superconducting linear compressor compresses in one or two stages below the critical temperature of the coil material. The former has a more compact structure, and the theoretical energy efficiency ratio (Carnot COP) of the J-T cycle itself is higher. The latter is beneficial to achieve a larger pressure ratio and reduce the cost of the compressor, and can be selected according to actual needs.

(2) The present invention uses a superconducting linear compressor to work in a low temperature environment of about 20K to compress the working medium of the J-T throttling refrigeration cycle in the liquid helium temperature zone, which is beneficial to increase the actual pressure ratio before and after throttling, and improve the cycle cooling performance. At the same time, since the superconducting coil is used in the superconducting linear compressor, the copper loss caused by resistance in the linear motor of the superconducting linear compressor is eliminated, and the efficiency of the compressor is effectively improved. Therefore, the J-T throttling refrigeration cycle in the liquid helium temperature zone driven by the superconducting linear compressor will have higher efficiency, and also have the advantages of long life and high reliability.

Description of drawings

Fig. 1 is a schematic diagram of the first embodiment of the low-temperature linear compressor-driven J-T throttling refrigeration cycle system of the present invention.

Fig. 2 is a schematic diagram of the second embodiment of the low-temperature linear compressor-driven J-T throttling refrigeration cycle system of the present invention.

Fig. 3 is a schematic diagram of a third embodiment of the low-temperature linear compressor-driven J-T throttling refrigeration cycle system of the present invention.

Fig. 4 is a T-s schematic diagram of the circulation system shown in Fig. 1 .

Fig. 5 is a T-s schematic diagram of the circulation system shown in Fig. 2 .

Among them: 1: One-stage low-temperature linear compressor, 2: One-stage pre-cooling heat exchanger, 3: Pre-throttle heat exchanger, 4: Throttle valve, 5: Evaporator, 6: Pre-cooling mechanism, 7: One 1st stage low temperature linear compressor surface coil, 8: linear compressor, 9: 1st stage heat exchanger, 10: high temperature pre-cooling heat exchanger, 11: 2nd stage heat exchanger, 12: 2nd stage low temperature linear compressor, 13 : Two-stage low-temperature linear compressor surface coil, 14: Two-stage pre-cooling heat exchanger.

Detailed ways

Example 1

As shown in Figure 1, a J-T throttling refrigeration cycle system driven by a low-temperature linear compressor includes a refrigeration unit and a pre-cooling unit. The refrigeration unit includes a one-stage low-temperature linear compressor 1, a pre-throttle heat exchanger 3, a Valve 4 and evaporator 5; the pre-cooling unit includes a primary pre-cooling heat exchanger 2 and a pre-cooling mechanism 6, wherein the primary low-temperature linear compressor 1 is a superconducting linear compressor.

The connection relationship between the components of the refrigeration unit and the pre-cooling unit is as follows:

According to the refrigerant flow direction, the outlet of the first-stage low-temperature linear compressor 1 is sequentially connected with the high-temperature side pipeline of the first-stage precooling heat exchanger 2, the high-temperature side pipeline of the pre-throttle heat exchanger 3, the throttle valve 4 and the pipeline through the pipeline. The inlet of the evaporator 5 is connected, and the outlet of the evaporator 5 is connected with the low-temperature side pipeline of the heat exchanger 3 before throttling and the inlet of the compressor 1 through pipelines to form a circulation loop;

According to the flow direction of the precooling agent, the outlet of the precooling mechanism 6 is connected to the low-temperature side pipeline of the first-stage precooling heat exchanger 2, the surface coil 7 of the first-stage low-temperature linear compressor 1, and the inlet of the precooling mechanism 6 through pipelines. Circulating precooling circuit.

The working process of the working medium in the refrigeration unit and the pre-cooling unit are as follows:

The working process of the refrigerant in the refrigeration unit is as follows: the refrigerant is compressed by the first-stage low-temperature linear compressor 1 to high pressure and discharged, and flows through the high-temperature side pipeline of the first-stage pre-cooling heat exchanger 2 and the pre-throttling heat exchanger 3 and Throttle valve 4, throttling at throttle valve 4 to a low pressure and reaching the liquid helium temperature zone, flows into the evaporator 5, evaporates the gas through the evaporator 5, enters the low-temperature side pipeline of the heat exchanger 3 before throttling, and finally returns to One stage low temperature linear compressor 1.

The working process of the pre-coolant in the pre-cooling unit is as follows: the pre-coolant starts from the pre-cooling mechanism 6, flows through the first-stage pre-cooling heat exchanger 2 and the surface coil 7 of the first-stage low-temperature linear compressor, and cools the first-stage low-temperature linear compressor. The machine 1 exports the working medium and the first-stage low-temperature linear compressor 1 and then returns to the pre-cooling mechanism 6 .

The precooling mechanism 6 needs to provide a cold source with a temperature below 20K and a power device for delivering precoolant. The precooling mechanism can choose a regenerative refrigeration mechanism with helium as the working fluid (GM refrigerator, Stirling refrigerator, GM pulse tube refrigerator, Stirling pulse tube refrigerator or Stirling/pulse tube hybrid refrigerator). The first coil of the first-stage low-temperature linear compressor adopts a superconducting material with a critical temperature higher than 20K. The system is installed according to the above process and requirements. After the installation is completed, vacuum the interior of the system to about 10 ^-2 Pa, then fill it with high-purity helium, keep it for about 5 minutes, and then vacuum the interior of the system to about 10 ^-2 Pa. After repeated vacuuming and inflating for 3-4 times, the high-purity helium at the working pressure is finally charged to ensure the purity of the helium working medium in the system. Turn on the pre-cooling mechanism 6, so that the pre-coolant in the pre-cooling mechanism 6 flows through the first-stage pre-cooling heat exchanger 2 to pre-cool the outlet working medium of the first-stage low-temperature linear compressor 1 to a temperature of 20K or below, and then flows through the first-stage low-temperature The surface coil 7 of the linear compressor cools the first-stage low-temperature linear compressor 1 to below the critical temperature of the coil material of the first-stage low-temperature linear compressor 1 , and finally flows back to the pre-cooling mechanism 6 . Then, the operating frequency of the first-stage low-temperature linear compressor 1 is adjusted to the optimum operating frequency of the JT throttling refrigeration cycle in the liquid helium temperature zone. Before the system is stable, adjust the pre-cooling mechanism 6 to ensure stable operation below the critical temperature of the coil material of the first-stage low-temperature linear compressor 1, and the outlet temperature of the working medium of the first-stage pre-cooling heat exchanger 2 is stable at 20K or below. After the system is stable, the liquid helium temperature and corresponding cooling capacity can be obtained at the evaporator 5 . FIG. 4 is a schematic diagram of Ts of the JT throttling refrigeration cycle system driven by a low-temperature linear compressor in this embodiment. Each numbered curve in Fig. 4 is the process curve of the working fluid in the corresponding numbered part in Fig. 1 .

Example 2

As shown in Figure 2, a J-T throttling refrigeration cycle system driven by a low-temperature linear compressor is different from Embodiment 1 in that: the outlet of the high-temperature side pipeline of the first-stage pre-cooling heat exchanger 2 and the high-temperature side of the pre-throttling heat exchanger 3 A two-stage low-temperature linear compressor 12 and a two-stage precooling heat exchanger 14 are also arranged on the pipeline between the pipeline inlets. The inlet of the two-stage low-temperature linear compressor 12 is connected with the high-temperature side pipeline of the first-stage pre-cooling heat exchanger 2, and the outlet of the two-stage low-temperature linear compressor 12 is connected to the high-temperature side pipeline of the two-stage pre-cooling heat exchanger 14 and throttled. The high temperature side pipeline inlet of the front heat exchanger 3 is connected; the low temperature side pipeline inlet of the secondary precooling heat exchanger 14 is connected with the outlet of the precooling mechanism 6 through the pipeline at the same time, and the low temperature side pipeline of the secondary precooling heat exchanger 14 The outlet of the road communicates with the inlet of the surface coil 13 of the two-stage low-temperature linear compressor 12;

The precooling mechanism 6 needs to provide a cold source with a temperature below 20K and a power device for delivering precoolant. The precooling mechanism can choose a regenerative refrigeration mechanism with helium as the working fluid (GM refrigerator, Stirling refrigerator, GM pulse tube refrigerator, Stirling pulse tube refrigerator or Stirling/pulse tube hybrid refrigerator). The first coil of the first-stage low-temperature linear compressor adopts a superconducting material with a critical temperature higher than 20K. The system is installed according to the above process and requirements. After the installation is completed, vacuum the interior of the system to about 10 ^-2 Pa, then fill it with high-purity helium, keep it for about 5 minutes, and then vacuum the interior of the system to about 10 ^-2 Pa. After repeated vacuuming and inflating for 3-4 times, the high-purity helium at the working pressure is finally charged to ensure the purity of the helium working medium in the system. Open the pre-cooling mechanism 6, so that the pre-coolant in the pre-cooling mechanism 6 flows through the primary pre-cooling heat exchanger 2 and the secondary pre-cooling heat exchanger 14 respectively, and the primary low-temperature linear compressor 1 and the secondary low-temperature linear compressor The outlet temperature of the machine 12 is cooled to 20K and below, and then flows through the surface coil 7 of the first-stage low-temperature linear compressor and the surface coil 13 of the second-stage low-temperature compression and surface coil 13 respectively, and the first-stage low-temperature linear compressor 1 and the second-stage low-temperature linear compressor The compressor 12 is cooled to below the critical temperature of the coil material of the first-stage low-temperature linear compressor 1 and the second-stage low-temperature linear compressor 12 , and finally flows back to the pre-cooling mechanism 6 . Then, the operating frequency of the first-stage low-temperature linear compressor 1 is adjusted to the optimum operating frequency of the JT throttling refrigeration cycle in the liquid helium temperature zone. Before the system is stable, adjust the pre-cooling mechanism 6 to ensure stable operation below the critical temperature of the coil material of the first-stage low-temperature linear compressor 1, and the outlet temperature of the working medium of the first-stage pre-cooling heat exchanger 2 is stable at 20K or below. After the system is stable, the liquid helium temperature and corresponding cooling capacity can be obtained at the evaporator 5 .

Example 3

As shown in Figure 3, a J-T throttling refrigeration cycle system driven by a low-temperature linear compressor includes a refrigeration unit and a pre-cooling unit. The refrigeration unit includes a one-stage low-temperature linear compressor 1, a pre-throttle heat exchanger 3, a Valve 4, evaporator 5, linear compressor 8, primary heat exchanger 9, high temperature precooling heat exchanger 10 and secondary heat exchanger 11; the precooling unit includes primary precooling heat exchanger 2 and precooling mechanism 6. The first-stage low-temperature linear compressor 1 is a superconducting linear compressor.

The working process of the working medium in the refrigeration unit and the pre-cooling unit are as follows:

The working process of the refrigerant in the refrigeration unit is: the refrigerant is compressed by the linear compressor 8 to high pressure and discharged, flows through the primary heat exchanger 9, the high-temperature pre-cooling heat exchanger 10 and the secondary heat exchanger 11, and then enters the primary stage Low-temperature linear compressor 1, compressed again to a higher pressure and discharged, flows through the first-stage pre-cooling heat exchanger 2, pre-throttle heat exchanger 3 high-temperature side pipeline and throttle valve 4, at the throttle valve 4 Throttling to low pressure and reaching the liquid helium temperature, it flows into the evaporator 5, and after being evaporated by the evaporator 5, the gas flows through the low-temperature side pipeline of the heat exchanger 3 before throttling, the low-temperature side pipeline of the secondary heat exchanger 11 and the primary The low-temperature side pipeline of the heat exchanger 9 finally returns to the linear compressor 8 . At the same time, the cooling capacity introduced into the high-temperature pre-cooling heat exchanger 10 directly cools the working medium at the outlet of the pipeline on the high-temperature side of the primary heat exchanger 9 . The pre-coolant starts from the pre-cooling mechanism 6, flows through the first-stage pre-cooling heat exchanger 2 and the surface coil 7 of the first-stage low-temperature linear compressor, and cools the outlet working medium of the first-stage low-temperature linear compressor 1 and the first-stage low-temperature linear compressor. Return to the pre-cooling mechanism 6 after the machine 1. The precooling mechanism 6 needs to provide a cold source with a temperature below 20K and a power device for delivering precoolant.

The first coil of the first-stage low-temperature linear compressor adopts a superconducting material with a critical temperature higher than 20K. The system is installed according to the above process and requirements. After the installation is completed, vacuum the interior of the system to about 10 ^-2 Pa, then fill it with high-purity helium, keep it for about 5 minutes, and then vacuum the interior of the system to about 10 ^-2 Pa. After repeated vacuuming and inflating for 3-4 times, the high-purity helium at the working pressure is finally charged to ensure the purity of the helium working medium in the system. Introduce the working fluid in the high-temperature pre-cooling heat exchanger 10 into the cooling liquid helium JT throttling cycle, open the pre-cooling mechanism 6, and make the pre-coolant in the pre-cooling mechanism 6 flow through the surface coil 7 of the first-stage low-temperature linear compressor The first-stage low-temperature linear compressor 1 is cooled to below the critical temperature of the coil material of the first-stage low-temperature linear compressor 1 . Then, respectively adjust the operating frequency of the linear compressor 8 and the first-stage low-temperature linear compressor 1 to the optimum operating frequency of the JT throttling refrigeration cycle in the liquid helium temperature zone. Before the system stabilizes, adjust the cooling capacity introduced by the high-temperature pre-cooling heat exchanger 10 and the pre-cooling mechanism 6 to ensure that the first-stage low-temperature linear compressor 1 operates stably below the critical temperature of the coil material, and the first-stage pre-cooling heat exchanger 2. The outlet temperature of the working fluid is stable at 20K and below. After the system is stable, the temperature of the liquid helium and the corresponding cooling capacity can be obtained at the evaporator 9 .

Fig. 5 is a T-S schematic diagram of a J-T throttling refrigeration cycle system driven by a low-temperature linear compressor in an embodiment. Each numbered curve in Fig. 5 is the process curve of the working medium in the corresponding numbered part in Fig. 3 .

Claims (7)

1. the J-T throttling refrigeration circulatory system that drives of a low temperature Linearkompressor, comprise refrigeration unit and precooling unit, it is characterized in that, described refrigeration unit comprises a grade low-temp Linearkompressor (1), the front heat exchanger (3) of throttling, choke valve (4) and evaporimeter (5); Described precooling unit comprises one-level precool heat exchanger device (2) and precooling mechanism (6); According to refrigerant flow direction, the outlet of a described grade low-temp Linearkompressor (1) is communicated with high temperature side pipeline, choke valve (4) and evaporimeter (5) entrance of heat exchanger (3) before the high temperature side pipeline of one-level precool heat exchanger device (2), the throttling successively by pipeline, evaporimeter (5) outlet pass through pipeline successively with throttling before low temperature side pipeline and compressor (1) entrance of heat exchanger (3) be communicated with the formation closed circuit; Flow to according to precooling agent, described precooling mechanism (6) outlet is communicated with the pre-cold loop of formation circulation with the low temperature side pipeline of one-level precool heat exchanger device (2), surperficial coil pipe (7) and precooling mechanism (6) entrance of a grade low-temp Linearkompressor (1) successively by pipeline.

2. the J-T throttling refrigeration circulatory system of low temperature Linearkompressor driving according to claim 1 is characterized in that, a described grade low-temp Linearkompressor (1) is the superconduction Linearkompressor.

3. the J-T throttling refrigeration circulatory system that drives of low temperature Linearkompressor according to claim 1, it is characterized in that, also be provided with two grade low-temp Linearkompressors (12) and secondary precool heat exchanger device (14) on the pipeline before the outlet of described one-level precool heat exchanger device (2) high temperature side pipeline and the throttling between heat exchanger (3) the high temperature side pipeline entrance; The high temperature side pipeline connection of described two grade low-temp Linearkompressor (12) entrances and one-level precool heat exchanger device (2), the outlet of two grade low-temp Linearkompressors (12) is communicated with heat exchanger (3) high temperature side pipeline entrance before the throttling by the high temperature side pipeline of secondary precool heat exchanger device (14); The low temperature side pipeline entrance of described secondary precool heat exchanger device (14) exports with precooling mechanism (6) simultaneously by pipeline and is communicated with, and outlet is communicated with surperficial coil pipe (13) entrance of two grade low-temp Linearkompressors (12); Surperficial coil pipe (13) outlet of two grade low-temp Linearkompressors (12) is communicated with the entrance of precooling mechanism (6) by pipeline simultaneously.

4. the J-T throttling refrigeration circulatory system of low temperature Linearkompressor driving according to claim 3 is characterized in that, described two grade low-temp Linearkompressors (12) are the superconduction Linearkompressor.

5. the J-T throttling refrigeration circulatory system that drives of low temperature Linearkompressor according to claim 1, it is characterized in that, also be provided with Linearkompressor (8), first-class heat exchanger (9), High Temperature Pre cold heat exchanger (10), secondary heat exchanger (11) on the pipeline before the described throttling between the outlet of the low temperature side pipeline of heat exchanger (3) and grade low-temp Linearkompressor (1) entrance; According to refrigerant flow direction, the outlet of the low temperature side pipeline of heat exchanger (3) is communicated with described Linearkompressor (8) entrance with the low temperature side pipeline of secondary heat exchanger (11), the low temperature side pipeline of first-class heat exchanger (9) successively by pipeline before the described throttling, and Linearkompressor (8) exports and passes through pipeline and be communicated with described grade low-temp Linearkompressor (a 1) entrance with the high temperature side pipeline of high temperature side pipeline, High Temperature Pre cold heat exchanger (10) and the secondary heat exchanger (11) of first-class heat exchanger (9) successively.

6. the J-T throttling refrigeration circulatory system that drives of the described low temperature Linearkompressor of arbitrary claim according to claim 1-5, it is characterized in that, described precooling mechanism (6) is hydrogen absorption type refrigerating mechanism, the J-T throttling refrigeration mechanism take hydrogen as working medium, the J-T throttling refrigeration mechanism take nitrogen as working medium or the regenerative refrigerating mechanism take helium as working medium.

7. the J-T throttling refrigeration circulatory system that drives of described low temperature Linearkompressor according to claim 2 is characterized in that, described cold-producing medium is helium, and described precooling mechanism (6) is for providing the precooling mechanism of the following temperature low-temperature receiver of 20K; The coil of described superconduction Linearkompressor is the superconductor that critical-temperature is higher than 20K; The cold-producing medium of described precool heat exchanger device (2) refrigerant outlet need be chilled to 20K and following temperature in advance.

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