Refrigerating system capable of recycling expansion work

Abstract

The refrigerating system comprises a compression type refrigerating unit and a regenerative refrigerating unit, the compression type refrigerating unit comprises a compressor, a high-pressure gas pipeline, a precooling section heat exchanger, an expansion device, a cold end heat exchanger and a low-pressure gas pipeline, and the compressor comprises a compression cavity A and a compression piston sliding in the compression cavity A; the regenerative refrigeration unit comprises a pressure wave generator, a heat radiator, a heat regenerator, a heat absorber and a pressure wave transmission pipe, the heat absorber serves as a cold head to precool a refrigerant in the precooling section heat exchanger, and a slidable expansion piston is arranged in the pressure wave transmission pipe; a compression piston of the compression type refrigeration unit and an expansion piston of the regenerative refrigeration unit are coupled into a whole and slide in a compression cavity A to compress a refrigerant in the compression cavity A, expansion work of the regenerative refrigeration unit is converted into compression power of the compression type refrigeration unit, external energy input of the refrigeration system is reduced, and the energy utilization efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of cryogenic refrigeration technology, specifically to a refrigeration system with recoverable expansion work, applicable to scientific and technological fields requiring cryogenic refrigeration, such as quantum computing, superconducting magnets, space exploration, and fundamental physics research. Background Technology

[0002] Joule-Thomson (JT) throttling refrigerators are widely used in infrared detection, cryogenic superconductivity, and space science due to their simple structure, high reliability, and lack of moving parts at the cold end. However, traditional JT throttling refrigerators typically require a JT compressor to provide high-pressure refrigerant before throttling, and to achieve a cooling effect, the high-pressure side temperature must be lowered below the conversion temperature before throttling. Therefore, the high-pressure refrigerant must be fully pre-cooled before throttling.

[0003] In existing technologies, independent external pre-cooling stage refrigerators (such as pulse tube refrigerators and thermoacoustic refrigerators) are generally used to pre-cool the gas before JT throttling. However, regenerative refrigerators, such as pulse tube refrigerators and thermoacoustic refrigerators, only provide cooling capacity. The acoustic work or expansion work of pulse tube refrigerators and thermoacoustic refrigerators is usually directly dissipated or only used to maintain their own circulation, and is not recovered for driving the JT compressor. They do not participate in the generation of high-pressure refrigerant in the JT throttling refrigeration system, resulting in defects such as low system integration and low energy utilization efficiency.

[0004] Therefore, there is an urgent need for a highly efficient refrigeration system with high system integration and high energy utilization efficiency. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art. The purpose of this invention is to provide a refrigeration system that integrates compression refrigeration and regenerative refrigeration and can recover expansion work. By integrating the expansion piston of the regenerative refrigeration unit and the compression piston of the JT compressor, the expansion work generated by the regenerative refrigeration unit is converted into the power of the compression piston in the compression refrigeration unit. At the same time, the heat absorber is used as a cold head to pre-cool the refrigerant in the heat exchanger of the pre-cooling section in the compression refrigeration unit, realizing the integrated coupling of "pre-cooling + power supply" and improving the system's energy efficiency and integration.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows: A refrigeration system capable of recovering expansion work includes a compression refrigeration unit and a regenerative refrigeration unit; The compression refrigeration unit includes a compressor, a high-pressure gas pipeline, a pre-cooling section heat exchanger, an expansion device, a cold-end heat exchanger, and a low-pressure gas pipeline; the expansion device is disposed on the high-pressure gas pipeline between the cold-end heat exchanger and the pre-cooling section heat exchanger; the compressor includes a compression chamber A, an exhaust valve, and an intake valve, the compression chamber A is connected to the high-pressure gas pipeline through the exhaust valve, and the low-pressure gas pipeline is connected to the compression chamber A through the intake valve; The refrigerant in compression chamber A is pressurized by the compressor and flows to the precooling section heat exchanger via the exhaust valve and high-pressure gas pipeline. After being precooled by the precooling section heat exchanger, the high-pressure refrigerant expands through the expansion device. The cooling capacity generated by the expanded refrigerant is used to cool the load via the cold end heat exchanger. The refrigerant that has passed through the cold end heat exchanger flows back to compression chamber A via the low-pressure gas pipeline and the suction valve. A sliding compression piston is provided in compression chamber A. By coordinating the timing of the exhaust valve, the suction valve, and the movement of the compression piston, the intermittent compression of the gas in compression chamber A by the reciprocating motion of the compression piston is converted into a continuous high-pressure refrigerant output flowing to the high-pressure gas pipeline. The regenerative refrigeration unit includes a pressure wave generator for generating pressure fluctuations and a heat exchanger, a regenerator, a heat absorber, and a pressure wave transmission pipe connected in sequence along the direction of pressure wave energy propagation. A slidable expansion piston is provided in the room temperature end of the pressure wave transmission pipe. The heat absorber acts as a cold head to pre-cool the refrigerant in the pre-cooling section heat exchanger. The compression piston of the compression refrigeration unit and the expansion piston of the regenerative refrigeration unit are coupled together and slide within the compression chamber A to compress the gaseous refrigerant within the compression chamber A, so that the expansion work of the expansion piston of the regenerative refrigeration unit is recovered as mechanical work or part of the mechanical work to drive the compression piston of the compression refrigeration unit.

[0007] Furthermore, the compressor also includes a drive device that provides motion power to the combination of the compression piston of the compression refrigeration unit and the expansion piston of the regenerative refrigeration unit; the drive device is an electromagnetic drive device or a mechanical drive device; the refrigeration system includes a phase coordination control system, which controls the motion phase of the expansion piston and the piston of the pressure wave generator, so that the regenerative refrigeration unit produces a sufficient cooling effect.

[0008] Furthermore, the driving device is a first electromagnetic driving device; a pair of the first electromagnetic driving devices drive the compression piston to reciprocate within the compression chamber A by switching on an alternating current.

[0009] Furthermore, the pressure wave generator includes a compression chamber B, a piston sliding within the compression chamber B, and a pair of second electromagnetic drive devices located outside the compression chamber B. The pair of second electromagnetic drive devices drive the piston of the pressure wave generator to reciprocate within the compression chamber B by switching on an alternating current. The phase coordination control system controls the movement phase of the expansion piston and the piston of the pressure wave generator, converting the expansion work generated by the regenerative refrigeration unit into mechanical work that drives the reciprocating motion of the compression piston.

[0010] Furthermore, the regenerative refrigeration unit is a regenerative refrigerator with an expansion chamber, and the regenerative refrigerator is a pulse tube refrigerator, a Stirling refrigerator, or a thermoacoustic refrigerator.

[0011] Furthermore, the regenerative refrigeration unit is a pulse tube refrigeration machine, the pressure wave transmission tube is a pulse tube, and the expansion piston slides against the inner wall of the room temperature end of the pulse tube.

[0012] Furthermore, the pressure wave generator has two sets, and the pistons of the two sets of pressure wave generators move towards each other and are arranged opposite each other. The pistons of the two sets of pressure wave generators together form a compression chamber B. The volume swept by the piston movement of the two sets of pressure wave generators is doubled, and the vibrations caused by the piston movement of the two sets of pressure wave generators cancel each other out.

[0013] Furthermore, the compressor has two sets, and the compression pistons of the two sets of compressors move towards each other and are arranged opposite each other. The two sets of compression pistons together form the compression chamber A of the compressor. The volume swept by the movement of the two sets of compression pistons is doubled, and the vibrations caused by the movement of the two sets of compression pistons cancel each other out.

[0014] Furthermore, the two sets of compressors are arranged in parallel or in series; when the two sets of compressors are arranged in parallel, the two sets of compressors provide high-pressure gas with the same pressure ratio to the compression refrigeration unit; when the two sets of compressors are arranged in series, the high-pressure gas provided by the upper stage compressor is compressed twice by the lower stage compressor and then provided to the compression refrigeration unit to output high-pressure gas with a higher compression ratio.

[0015] Furthermore, the pressure wave generator is a thermoacoustic engine or a loudspeaker.

[0016] Furthermore, the compression refrigeration unit is a JT throttling refrigeration unit, which also includes a JT counter-current heat exchanger. The high-pressure side inlet of the JT counter-current heat exchanger is connected to the cold end outlet of the pre-cooling section heat exchanger. The high-pressure side outlet of the JT counter-current heat exchanger is connected to the low-pressure side inlet of the JT counter-current heat exchanger via the expansion device and the cold end heat exchanger. The low-pressure side outlet of the JT counter-current heat exchanger is connected to the suction valve of the compressor. The high-pressure refrigerant in the high-pressure gas pipeline is pre-cooled by the pre-cooling section heat exchanger and the JT counter-current heat exchanger in sequence, and then flows to the expansion device for throttling expansion. It provides cooling capacity to the load at the cold end heat exchanger.

[0017] Furthermore, the compression refrigeration unit also includes a counter-current heat exchanger, wherein the high-pressure side inlet of the counter-current heat exchanger is connected to the exhaust valve, the high-pressure side outlet of the counter-current heat exchanger is connected to the hot end inlet of the pre-cooling section heat exchanger, the low-pressure side inlet of the counter-current heat exchanger is connected to the low-pressure side outlet of the JT counter-current heat exchanger, and the low-pressure side outlet of the counter-current heat exchanger is connected to the suction valve.

[0018] Furthermore, the expansion device is a throttling valve or an expander, and the high-pressure refrigerant in the high-pressure gas pipeline is pre-cooled by the heat exchanger in the pre-cooling section before being throttled and expanded by the throttling valve or expander.

[0019] A refrigeration system with recoverable expansion work includes a refrigerant circulation unit and a regenerative refrigeration unit; The refrigerant circulation unit includes a fluid pump, a high-pressure fluid pipeline, a pre-cooling section heat exchanger, a cold end heat exchanger, and a low-pressure fluid pipeline; the fluid pump includes a pump cylinder, a discharge valve, and a suction valve, the pump cylinder is connected to the high-pressure fluid pipeline through the discharge valve, and the low-pressure fluid pipeline is connected to the pump cylinder through the suction valve; The refrigerant in the pump cylinder is pressurized by the fluid pump and flows to the pre-cooling end heat exchanger through the discharge valve and high-pressure fluid pipeline. After being pre-cooled by the pre-cooling section heat exchanger, the high-pressure refrigerant flows to the cold end heat exchanger to cool the load. The refrigerant after passing through the cold end heat exchanger flows back to the pump cylinder through the low-pressure fluid pipeline and the suction valve. The pump cylinder is equipped with a sliding fluid pump piston. By coordinating the movement of the discharge valve, the suction valve, and the fluid pump piston, the intermittent pressurization of the reciprocating motion of the fluid pump piston on the refrigerant in the pump cylinder is converted into a continuous high-pressure refrigerant output to the high-pressure fluid pipeline. The regenerative refrigeration unit includes a pressure wave generator for generating pressure fluctuations and a heat exchanger, a regenerator, a heat absorber, and a pressure wave transmission pipe connected in sequence along the direction of pressure wave energy propagation. A slidable expansion piston is provided in the room temperature end of the pressure wave transmission pipe. The heat absorber acts as a cold head to pre-cool the refrigerant in the heat exchanger of the pre-cooling section. The fluid pump piston of the refrigerant circulation unit and the expansion piston of the regenerative refrigeration unit are coupled together and slide within the pump cylinder to pressurize the refrigerant within the pump cylinder, so that the expansion work of the expansion piston of the regenerative refrigeration unit is recovered as mechanical work or part of the mechanical work to drive the fluid pump piston of the refrigerant circulation unit.

[0020] Furthermore, the fluid pump also includes a drive device that provides motion power to the combination of the fluid pump piston of the refrigerant circulation unit and the expansion piston of the regenerative refrigeration unit; the drive device is an electromagnetic drive device or a mechanical drive device; the refrigeration system includes a phase coordination control system, which controls the motion phase of the expansion piston and the piston of the pressure wave generator, so that the regenerative refrigeration unit generates a sufficient cooling effect.

[0021] Furthermore, the driving device is a first electromagnetic driving device; a pair of the first electromagnetic driving devices drives the fluid pump piston to reciprocate within the pump cylinder by switching on an alternating current.

[0022] Furthermore, the pressure wave generator includes a compression chamber B, a piston sliding within the compression chamber B, and a pair of second electromagnetic drive devices located outside the compression chamber B. The pair of second electromagnetic drive devices drive the piston of the pressure wave generator to reciprocate within the compression chamber B by switching on an alternating current. The phase coordination control system controls the movement phase of the expansion piston and the piston of the pressure wave generator, converting the expansion work generated by the regenerative refrigeration unit into mechanical work that drives the fluid pump piston to reciprocate.

[0023] Furthermore, the regenerative refrigeration unit is a regenerative refrigerator with an expansion chamber, and the regenerative refrigerator is any one of a pulse tube refrigerator, a Stirling refrigerator, and a thermoacoustic refrigerator.

[0024] Furthermore, the regenerative refrigeration unit is a pulse tube refrigeration machine, the pressure wave transmission tube is a pulse tube, and the expansion piston slides against the inner wall of the room temperature end of the pulse tube.

[0025] Furthermore, the pressure wave generator has two sets, and the pistons of the two sets of pressure wave generators move towards each other and are arranged opposite each other. The pistons of the two sets of pressure wave generators together form a compression chamber B. The volume swept by the piston movement of the two sets of pressure wave generators is doubled, and the vibrations caused by the piston movement of the two sets of pressure wave generators cancel each other out.

[0026] Furthermore, the fluid pump has two sets, and the fluid pump pistons of the two sets of fluid pumps move towards each other and are arranged opposite each other. The two sets of fluid pump pistons together form the pump cylinder of the fluid pump. The volume swept by the movement of the two sets of fluid pump pistons is doubled, and the vibrations caused by the movement of the two sets of fluid pump pistons cancel each other out.

[0027] Furthermore, the two sets of fluid pumps are arranged in parallel or in series. When the two sets of fluid pumps are arranged in parallel, the two sets of fluid pumps provide the refrigerant circulation unit with the same high-pressure refrigerant. When the two sets of fluid pumps are arranged in series, the high-pressure refrigerant provided by the upper-level fluid pump is pressurized again by the lower-level fluid pump and then provided to the refrigerant circulation unit, resulting in a higher output pressure of high-pressure refrigerant.

[0028] Furthermore, the pressure wave generator is a thermoacoustic engine or a loudspeaker.

[0029] Furthermore, the refrigerant circulation unit also includes a first counter-current heat exchanger. The high-pressure side inlet of the first counter-current heat exchanger is connected to the cold end outlet of the pre-cooling section heat exchanger. The high-pressure side outlet of the first counter-current heat exchanger is connected to the low-pressure side inlet of the first counter-current heat exchanger via the cold end heat exchanger. The low-pressure side outlet of the first counter-current heat exchanger is connected to the suction valve of the fluid pump. The high-pressure refrigerant in the high-pressure fluid pipeline flows sequentially from the pre-cooling section heat exchanger and the first counter-current heat exchanger to the cold end heat exchanger, where it provides cooling capacity to the load.

[0030] Furthermore, the refrigerant circulation unit also includes a second counter-current heat exchanger, the high-pressure side inlet of the second counter-current heat exchanger is connected to the discharge valve, the high-pressure side outlet of the second counter-current heat exchanger is connected to the hot end inlet of the pre-cooling section heat exchanger, the low-pressure side inlet of the second counter-current heat exchanger is connected to the low-pressure side outlet of the first counter-current heat exchanger, and the low-pressure side outlet of the second counter-current heat exchanger is connected to the suction valve.

[0031] The refrigeration system with recoverable expansion work provided by this invention uses a regenerative refrigeration unit as the precooling stage of a compression refrigeration unit. The expansion piston sliding within the pressure wave transmission tube in the regenerative refrigeration unit and the compression piston sliding within the compression chamber A in the compression refrigeration unit are coupled as a single unit. The expansion piston moves under the influence of the expansion work within the pressure wave transmission tube, driving the compression piston to slide within the compression chamber A to compress the refrigerant. This converts the expansion work of the regenerative refrigeration unit into partial compression power of the compressor in the compression refrigeration unit, providing high-pressure refrigerant to the high-pressure gas pipeline. This reduces the external energy input to the refrigeration system, improves its energy utilization efficiency, and eliminates the need for a separate compressor in the compression refrigeration unit, thus increasing the integration and reducing the system's size.

[0032] Furthermore, when the compression refrigeration unit is a JT throttling refrigeration unit and the regenerative refrigeration unit is a thermoacoustic refrigerator or a pulse tube refrigerator, the combination of thermoacoustic precooling and JT throttling refrigeration can meet the ultra-low temperature refrigeration requirements of cutting-edge fields such as quantum computing. Moreover, the cold end of the entire refrigeration system has no mechanical moving parts, no sealing wear and vibration interference, and can operate continuously and stably for a long time in a low temperature environment, reducing the external energy input of the refrigeration system and improving the energy utilization efficiency of the refrigeration system. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of a refrigeration system that integrates a compression refrigeration unit and a regenerative refrigeration unit and can recover expansion work in Embodiment 1 of the present invention. Figure 2 The first view shows the compressor of the compression refrigeration unit and the regenerative refrigeration unit integrated to form a refrigeration machine in Embodiment 1 of the present invention. Figure 3 The compressor of the compression refrigeration unit and the regenerative refrigeration unit in Embodiment 1 of the present invention is integrated to form a refrigeration machine on the second side. Figure 4 This is a schematic diagram of the refrigeration system in Embodiment 2 of the present invention, which integrates refrigerant circulation and regenerative refrigeration and can recover expansion work. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0037] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0038] Example 1 like Figures 1 to 3 The refrigeration system shown includes a compression refrigeration unit 1 and a regenerative refrigeration unit 2, with the regenerative refrigeration unit 2 serving as a precooling stage for the compression refrigeration unit 1.

[0039] like Figure 1 As shown, the compression refrigeration unit 1 includes a compressor 11, a cold-end heat exchanger 12, a high-pressure gas pipeline 13, a low-pressure gas pipeline 14, a pre-cooling section heat exchanger 15, and an expansion device 16. The compressor 11 includes a compression chamber A111 and an exhaust valve 112 and an intake valve 113 disposed on the wall of the compression chamber A111. The high-pressure refrigerant inlet of the high-pressure gas pipeline 13 is connected to the compression chamber A111 through the exhaust valve 112, and the low-pressure refrigerant outlet of the low-pressure gas pipeline 14 is connected to the compression chamber A111 through the intake valve 113. The compression chamber A111, the high-pressure gas pipeline 13, and the low-pressure gas pipeline 14 constitute the refrigerant circulation loop of the compression refrigeration unit 1. The cold end heat exchanger 12 is used to provide a cooling capacity Qc for the load in the cooling temperature range Tc. The pre-cooling section heat exchanger 15 is installed on the high-pressure gas pipeline 13. The expansion device 16 is installed on the high-pressure gas pipeline 13 between the cold end heat exchanger 12 and the pre-cooling section heat exchanger 15.

[0040] like Figure 1 As shown, the compressor 11 pressurizes the gaseous refrigerant in the compression chamber A111 into a high-pressure refrigerant, which then flows through the exhaust valve 112 to the high-pressure gas pipeline 13. The high-pressure refrigerant in the high-pressure gas pipeline 13 is pre-cooled by the pre-cooling section heat exchanger 15 and then flows to the expansion device 16. The pre-cooled refrigerant is further cooled by the expansion device 16 through throttling expansion. After cooling, the refrigerant flows to the cold end heat exchanger 12 to provide cooling capacity for the load. After heat exchange in the cold end heat exchanger 12, the refrigerant flows back to the compression chamber A111 of the compressor 11 through the low-pressure gas pipeline 14 and the suction valve 113.

[0041] like Figure 1 As shown, the regenerative refrigeration unit 2 includes a pressure wave generator 21 for generating pressure fluctuations and a heat exchanger 22, a regenerator 23, a heat absorber 24, and a pressure wave transmission pipe 25 connected sequentially along the direction of pressure wave energy propagation. The heat absorber 24 acts as a cold head to pre-cool the refrigerant in the pre-cooling section heat exchanger 15. Specifically, the heat absorbed Q0 is the heat absorbed by the heat absorber 24 from the refrigerant in the pre-cooling section heat exchanger 15, and the pre-cooling stage temperature T0 is the temperature range of the refrigerant in the pre-cooling section heat exchanger 15 after pre-cooling.

[0042] like Figure 1 As shown, a slidable compression piston 115 is provided inside the compression chamber A111 and is sealed to fit within the compression chamber A111. A slidable expansion piston 27 is provided inside the room temperature end of the pressure wave transmission pipe 25. The compression piston 115 of the compression refrigeration unit 1 and the expansion piston 27 of the regenerative refrigeration unit 2 are coupled as one unit, and the compression piston 115 and the expansion piston 27 together separate the pressure wave transmission pipe 25 and the compression chamber A111. Under the action of the expansion work in the pressure wave transmission pipe 25, the expansion piston 27 moves and drives the compression piston 115 to slide in the compression chamber A111 to compress the gaseous refrigerant in the compression chamber A111, providing high-pressure refrigerant to the high-pressure gas pipeline 13 of the compression refrigeration unit 1. The expansion piston 27 is used to recover the expansion work of the regenerative refrigeration unit 2 and convert it into the mechanical work or part of the mechanical work of the compression piston 115 in the compression refrigeration unit 1 to compress the refrigerant, so as to provide high-pressure refrigerant for the compression refrigeration unit 1.

[0043] like Figure 1 As shown, both the exhaust valve 112 and the intake valve 113 are one-way valves. The exhaust valve 112 controls the flow of high-pressure refrigerant from the compression chamber A111 to the high-pressure gas line 13, while the intake valve 113 controls the flow of low-pressure refrigerant from the low-pressure gas line 14 to the compression chamber A111. By coordinating the movements of the exhaust valve 112, the intake valve 113, and the compression piston 115, the intermittent compression of the gaseous refrigerant in the compression chamber A111 by the reciprocating motion of the compression piston 115 can be converted into a continuous output of high-pressure refrigerant flowing to the high-pressure gas line 13.

[0044] like Figure 1 As shown, the compressor 11 also includes a drive device that provides motion power to the compression piston 115 within the compression chamber A111; the drive device can be an electromagnetic drive device or a mechanical drive device. In some embodiments, the drive device is a first electromagnetic drive device 114; a pair of first electromagnetic drive devices 114 are located outside the compression chamber A111, and the pair of first electromagnetic drive devices 114 drive the compression piston 115 to reciprocate within the compression chamber A111 by switching on an alternating current. The frequency of the alternating current switched on by the first electromagnetic drive device 114 is 50-200Hz, and the electromagnetic work input to the first electromagnetic drive device 114 is W1.

[0045] like Figure 1 As shown, the pressure wave generator 21 includes a compression chamber B211, a piston 212 sliding within the compression chamber B211, and a pair of second electromagnetic drive devices 213 located outside the compression chamber B211. The pair of second electromagnetic drive devices 213 drive the piston 212 of the pressure wave generator to reciprocate within the compression chamber B211 by switching on an alternating current. There is a phase difference between the alternating current switched on by the first electromagnetic drive device 114 and the alternating current switched on by the second electromagnetic drive device 213. The refrigeration system also includes a phase coordination control system, which controls the movement phase of the expansion piston 27 and the piston 212 of the pressure wave generator, so that the heat absorber 24 of the regenerative refrigeration unit 2 generates a sufficient cooling effect and converts the expansion work generated by the regenerative refrigeration unit 2 into mechanical work to drive the reciprocating motion of the compression piston 115. Specifically, the phase difference between the movement phase of the expansion piston 27 and the movement phase of the piston 212 of the pressure wave generator is maintained at 90° to maximize the expansion work recovery efficiency.

[0046] This refrigeration system with recoverable expansion work uses a regenerative refrigeration unit 2 as the precooling stage of a compression refrigeration unit 1. The expansion piston 27, which slides in the pressure wave transmission pipe 25 in the regenerative refrigeration unit 2, and the compression piston 115, which slides in the compression chamber A111 in the compression refrigeration unit 1, are coupled together. The expansion piston 27 moves under the action of the expansion work in the pressure wave transmission pipe 25 and drives the compression piston 115 to slide in the compression chamber A111 to compress the gaseous refrigerant in the compression chamber A111. The whole formed by the expansion piston 27 and the compression piston 115 can convert the expansion work of the regenerative refrigeration unit 2 into part of the compression power of the compressor 11 in the compression refrigeration unit 1, and provide high-pressure refrigerant to the high-pressure gas pipeline 13. This can reduce the external energy input of the refrigeration system and improve the energy utilization efficiency of the refrigeration system. Moreover, the compression refrigeration unit 1 does not need to be equipped with a completely independent compressor, which can improve the integration of the refrigeration system and reduce the size of the refrigeration system.

[0047] In this embodiment, the expansion device 16 of the compression refrigeration unit 1 is specifically a throttling valve or an expander. The throttling valve or expander is installed on the high-pressure gas pipeline 13 between the cold end heat exchanger 12 and the pre-cooling section heat exchanger 15. The high-pressure refrigerant in the high-pressure gas pipeline 13 is pre-cooled by the pre-cooling section heat exchanger 15 and then expanded by the throttling valve or expander. After the high-pressure refrigerant expands, it cools down and provides cooling capacity for the load at the cold end heat exchanger 12.

[0048] like Figure 1 As shown, in some embodiments, the compression refrigeration unit 1 is a JT throttling refrigeration unit, which further includes a JT counter-current heat exchanger 17, and the expansion device 16 is specifically a JT throttling valve. The JT throttling valve is installed on the high-pressure gas pipeline 13 between the cold-end heat exchanger 12 and the pre-cooling section heat exchanger 15. The high-pressure gas in the high-pressure gas pipeline 13 expands and cools down after being throttled by the JT throttling valve, providing cooling capacity to the cold-end heat exchanger 12. The high-pressure side inlet of the JT counter-current heat exchanger 17 is connected to the cold-end outlet of the pre-cooling section heat exchanger 15. The high-pressure side outlet of the JT counter-current heat exchanger 17 is connected to the low-pressure side inlet of the JT counter-current heat exchanger 17 via the JT throttling valve and the cold-end heat exchanger 12. The low-pressure side outlet of the JT counter-current heat exchanger 17 is connected to the suction valve 113 of the compressor 11. The high-pressure refrigerant in the high-pressure gas pipeline 13 is pre-cooled sequentially by the pre-cooling section heat exchanger 15 and the JT counter-current heat exchanger 17 before flowing to the JT expansion valve for throttling and expansion. It generates cooling capacity at the cold-end heat exchanger 12 to provide cooling for the load. The JT counter-current heat exchanger 17 exchanges heat counter-currently between the high-pressure gas pipeline 13 and the low-pressure gas pipeline 14, recovering the cooling capacity of the refrigerant returning after throttling, further pre-cooling the high-pressure refrigerant, and improving system energy efficiency.

[0049] like Figure 1 As shown, in some embodiments, the JT throttling refrigeration unit further includes a counter-current heat exchanger 18. The high-pressure side inlet of the counter-current heat exchanger 18 is connected to the exhaust valve 112 of the compressor 11, the high-pressure side outlet of the counter-current heat exchanger 18 is connected to the hot end inlet of the pre-cooling section heat exchanger 15, the low-pressure side inlet of the counter-current heat exchanger 18 is connected to the low-pressure side outlet of the JT counter-current heat exchanger 17, and the low-pressure side outlet of the counter-current heat exchanger 18 is connected to the suction valve 113 of the compressor 11. The counter-current heat exchanger 18 performs counter-current heat exchange between the high-pressure gas pipeline 13 and the low-pressure gas pipeline 14, recovering the throttling-induced cooling capacity, further pre-cooling the high-pressure refrigerant, and improving system energy efficiency.

[0050] In this embodiment, the regenerative refrigeration unit 2 is a regenerative refrigerator with an expansion chamber. The regenerative refrigerator includes any one of a Stirling refrigerator, a pulse tube refrigerator, and a thermoacoustic refrigerator. The Stirling refrigerator, pulse tube refrigerator, and thermoacoustic refrigerator are used to generate a pre-cooling temperature range of 20-30K and output recoverable expansion work.

[0051] like Figure 1 , Figure 2 and Figure 3 As shown, in some embodiments of this example, the regenerative refrigeration unit 2 is a pulse tube refrigerator. When the regenerative refrigeration unit 2 is a pulse tube refrigerator, the pressure wave generator 21 can be a compressor. The pulse tube refrigerator includes a pulse tube 26 connected downstream of the absorber 24 along the direction of pressure wave energy propagation. The pulse tube 26 is connected to the pressure wave transmission tube 25, or the pressure wave transmission tube 25 is the pulse tube 26. The expansion piston 27 slides and seals against the inner wall of the pulse tube 26. The pressure wave generator 21 is used to input compression work or acoustic work W2 to establish a high-frequency alternating pressure wave in the pulse tube 26 to drive the working gas to reciprocate. The heat releaser 22, the regenerator 23, and the absorber 24 are connected sequentially along the direction of pressure wave energy propagation. The heat releaser 22 releases the compressed heat at the hot end of the regenerator 23 to the environment, maintaining a stable hot end temperature. Under the action of alternating pressure waves, the working gas in the regenerator 23 undergoes alternating compression and expansion within its internal channels. The working gas exchanges heat stably with the channel walls, forming a pre-cooled low temperature at the end near the receiver 24. The receiver 24, acting as a pre-cooling stage, absorbs heat from the heat exchanger 15 in the pre-cooling section of the JT throttling refrigeration unit, cooling the high-pressure refrigerant entering the JT throttling valve below its conversion temperature.

[0052] This integrated refrigeration system, combining a JT throttling refrigeration unit and thermoacoustic refrigeration with recoverable expansion work, can meet the ultra-low temperature refrigeration needs of cutting-edge fields such as quantum computing, as well as the refrigeration requirements of higher temperature regions. Furthermore, the entire refrigeration system has no moving mechanical parts at the cold end, eliminating sealing wear and vibration interference, allowing for long-term continuous and stable operation in low-temperature environments. This reduces the external energy input to the refrigeration system and improves its energy utilization efficiency. Moreover, the compression function of the JT throttling refrigeration unit is integrated between the pressure wave transmission tube 25 and the compression chamber A111, eliminating the need for a separate JT compressor. This increases the integration level of the refrigeration system and reduces its size and structural complexity.

[0053] It should also be noted that Reference 1 (Publication No.: CN103808056B) uses the expansion work of the room temperature expansion end of the pulse tube to pressurize the gas used for throttling in JT. However, this pressurization adds a second stage of compression to the existing compressor, resulting in three moving parts: the first is the piston of the pressure wave generator (not shown in the attached figure), the second is the piston of the compressor (not shown in the attached figure), and the third is the piston inside the pulse chamber. Essentially, the work recovered by the piston inside the pulse chamber is used to compress the compression chamber, forming the second stage of compression in the compressor, which is a two-stage compression structure. Since the compressor outlet is already at high pressure, the intake pressure of the intake and exhaust valve group of the compression chamber is the high pressure of the compressor outlet, making compression in the compression chamber very difficult to achieve. Furthermore, the piston inside the pulse chamber has no additional power drive; it is only passively driven by the pressure fluctuations of the pulse tube, which is also very difficult to achieve. This invention does not have the compressor found in Document 1 (Patent No.: CN 103808056 B) in its topological structure, thus eliminating one set of moving parts and leaving only two sets. It draws air directly from the low-pressure gas pipeline 14 via the intake valve 113, and provides partial compression power through a drive device (such as the first electromagnetic drive device 114). Therefore, it has only one stage of compression, with low-pressure inlet and high-pressure outlet. While a two-stage compression system could be implemented under specific conditions, both stages involve expansion work or acoustic work recovery, fundamentally different from the two-stage compression in Document 1 (Publication No.: CN103808056 B), where the first-stage compressor lacks acoustic work recovery.

[0054] like Figure 2 and Figure 3 As shown, in some embodiments of this example, the refrigeration system further includes a refrigeration unit housing 5, and two sets of pressure wave generators 21, both of which are fixed inside the refrigeration unit housing 5. The pistons 212 of the two sets of pressure wave generators 21 move towards each other and are positioned opposite each other. The pistons 212 of the two sets of pressure wave generators and the refrigeration unit housing 5 together enclose a compression chamber B211. The volume swept by the pistons 212 of the two sets of pressure wave generators is doubled, and the vibrations caused by the movement of the pistons 212 of the two sets of pressure wave generators cancel each other out.

[0055] like Figure 2 and Figure 3 As shown, in some embodiments of this example, the compressor 11 of the JT throttling refrigeration unit also has two sets. The two compression pistons 115 in the two sets of compressors 11 move towards each other and are arranged opposite each other. The two sets of compression pistons 115 and the refrigeration housing 5 together enclose the compression chamber A111 of the compressor 11. The volume swept by the movement of the two sets of compression pistons 115 is doubled, and the vibrations caused by the movement of the two sets of compression pistons 115 cancel each other out.

[0056] like Figure 2 and Figure 3 As shown, in some embodiments of this example, the two sets of compressors 11 are connected in parallel or in series. When the two sets of compressors 11 are connected in parallel, each set of compressors 11 provides high-pressure refrigerant with the same pressure ratio to the compression refrigeration unit 1. Compared with the method of setting a single set of compressors 11, this configuration can increase the flow rate of high-pressure refrigerant in the compression refrigeration unit 1, effectively doubling the refrigerant flow rate, which is beneficial to increasing the cooling capacity of the compression refrigeration unit 1. When the two sets of compressors 11 are connected in series, the high-pressure refrigerant provided by the upper-stage compressor 11 is compressed twice by the lower-stage compressor 11 before being supplied to the compression refrigeration unit 1. This configuration can achieve secondary compression of the high-pressure refrigerant, ultimately increasing the pressure of the high-pressure refrigerant supplied to the compression refrigeration unit 1, which is also beneficial to increasing the cooling capacity of the compression refrigeration unit 1.

[0057] Example 2 like Figure 4 The refrigeration system shown includes a refrigerant circulation unit 4 and a regenerative refrigeration unit 2. The difference from Embodiment 1 is that the refrigerant circulation unit 4, which does not have its own refrigeration capacity, is used instead of the compression refrigeration unit with its own refrigeration capacity in Embodiment 1. The refrigerant circulation unit 4 only provides a loop for the refrigerant circulation flow. The regenerative refrigeration unit 2 cools the refrigerant in the refrigerant circulation unit 4, and the cooled refrigerant cools the load 6.

[0058] like Figure 4 As shown, the refrigerant circulation unit 4 includes a fluid pump 41, a cold-end heat exchanger 42, a high-pressure fluid line 43 supplying refrigerant from the fluid pump 41 to the cold-end heat exchanger 42, and a low-pressure fluid line 44 supplying refrigerant from the cold-end heat exchanger 42 back to the fluid pump 41. The cold-end heat exchanger 42 is used to cool the load 6, and the high-pressure fluid line 43 is equipped with a pre-cooling section heat exchanger 45. The fluid pump 41 includes a pump cylinder 411, a discharge valve 412, and a suction valve 413. The high-pressure inlet of the high-pressure fluid line 43 is connected to the pump cylinder 411 through the discharge valve 412, and the low-pressure outlet of the low-pressure fluid line 44 is connected to the pump cylinder 411 through the suction valve 413.

[0059] like Figure 4As shown, the refrigerant in pump cylinder 411 is pressurized by fluid pump 41 and flows to pre-cooling section heat exchanger 45 through discharge valve 412 and high-pressure fluid pipeline 43. After pre-cooling by pre-cooling section heat exchanger 45, the high-pressure refrigerant flows to cold end heat exchanger 42 to cool load 6. The refrigerant after passing through cold end heat exchanger 42 flows back to pump cylinder 411 through low-pressure fluid pipeline 44 and suction valve 413. Pump cylinder 411 is equipped with a sliding fluid pump piston 415. By coordinating the movement of discharge valve 412, suction valve 413 and fluid pump piston 415, the intermittent pressurization of refrigerant in pump cylinder 411 by the reciprocating motion of fluid pump piston 415 is converted into continuous high-pressure refrigerant output to high-pressure fluid pipeline 43.

[0060] like Figure 4 As shown, the regenerative refrigeration unit 2 includes a pressure wave generator 21 for generating pressure fluctuations and a heat exchanger 22, a regenerator 23, a heat absorber 24, and a pressure wave transmission pipe 25 connected sequentially along the direction of pressure wave energy propagation. The heat absorber 24 acts as a cold head to pre-cool the refrigerant in the pre-cooling section heat exchanger 45. A sliding expansion piston 27 is provided inside the pressure wave transmission pipe 25.

[0061] like Figure 4 As shown, the fluid pump piston 415 of the refrigerant circulation unit 4 and the expansion piston 27 of the regenerative refrigeration unit 2 are coupled as one unit, and the fluid pump piston 415 and the expansion piston 27 together separate the pressure wave transmission pipe 25 and the pump cylinder 411. Under the action of expansion work in the pressure wave transmission pipe 25, the expansion piston 27 moves and drives the fluid pump piston 415 to slide in the pump cylinder 411 to compress the refrigerant in the pump cylinder 411, providing part of the kinetic power for the circulation of the refrigerant in the high-pressure fluid pipeline 43 of the refrigerant circulation unit 4.

[0062] like Figure 4 As shown, the fluid pump 41 also includes a drive device that provides partial motion power to the assembly of the fluid pump piston 415 of the refrigerant circulation unit 4 and the expansion piston 27 of the regenerative refrigeration unit 2; the drive device is an electromagnetic drive device or a mechanical drive device. In some embodiments, the drive device is a first electromagnetic drive device 414; a pair of first electromagnetic drive devices 414 are located outside the pump cylinder 411, and the pair of first electromagnetic drive devices 414 drive the fluid pump piston 415 to reciprocate within the pump cylinder 411 by switching on an alternating current. The frequency of the alternating current switched on by the first electromagnetic drive device 414 is 50-200Hz, and the electromagnetic work input to the first electromagnetic drive device 414 is W1.

[0063] like Figure 4As shown, the pressure wave generator 21 includes a compression chamber B211, a piston 212 sliding within the compression chamber B211, and a pair of second electromagnetic drive devices 213 located outside the compression chamber B211. The pair of second electromagnetic drive devices 213 drive the piston 212 of the pressure wave generator to reciprocate within the compression chamber B211 by switching on an alternating current. There is a phase difference between the alternating current switched on by the first electromagnetic drive device 114 and the alternating current switched on by the second electromagnetic drive device 213. The refrigeration system includes a phase coordination control system, which controls the movement phase of the expansion piston 27 and the piston 212 of the pressure wave generator 21, so that the regenerative refrigeration unit 2 generates a sufficient cooling effect and converts the expansion work generated by the regenerative refrigeration unit 2 into mechanical work to drive the fluid pump piston 415 to reciprocate. Specifically, the phase difference between the movement phase of the expansion piston 27 and the movement phase of the piston 212 of the pressure wave generator is maintained at 90° to maximize the expansion work recovery efficiency.

[0064] This refrigeration system with recoverable expansion work uses the expansion work of the regenerative refrigeration unit 2 to drive the fluid pump 41 in the refrigerant circulation unit 4, reducing the external energy input of the fluid pump 41 in the refrigerant circulation unit 4, improving the energy utilization efficiency of the refrigeration system, and the refrigerant circulation unit 4 does not need to be equipped with a separate fluid pump, which can improve the integration of the refrigeration system and reduce the size of the refrigeration system.

[0065] like Figure 4 As shown, in some embodiments, the refrigerant circulation unit 4 further includes a first counter-current heat exchanger 47. The high-pressure side inlet of the first counter-current heat exchanger 47 is connected to the cold end outlet of the pre-cooling section heat exchanger 45. The high-pressure side outlet of the first counter-current heat exchanger 47 is connected to the low-pressure side inlet of the first counter-current heat exchanger 47 via the cold end heat exchanger 42. The low-pressure side outlet of the first counter-current heat exchanger 47 is connected to the suction valve 413 of the fluid pump 41. The high-pressure refrigerant in the high-pressure fluid pipeline 43 flows to the cold end heat exchanger 42 after being pre-cooled by the pre-cooling section heat exchanger 45 and the first counter-current heat exchanger 47. The cold end heat exchanger 42 provides cooling capacity to cool the load 6. The first counter-current heat exchanger 47 performs counter-current heat exchange between the high-pressure fluid pipeline 43 and the low-pressure fluid pipeline 44, recovers the cooling capacity of the returning refrigerant, further pre-cools the high-pressure refrigerant, and improves the system energy efficiency.

[0066] like Figure 4As shown, in some embodiments, the refrigerant circulation unit 4 further includes a second counter-current heat exchanger 48. The high-pressure side inlet of the second counter-current heat exchanger 48 is connected to the discharge valve 412, the high-pressure side outlet of the second counter-current heat exchanger 48 is connected to the hot end inlet of the pre-cooling section heat exchanger 45, the low-pressure side inlet of the second counter-current heat exchanger 48 is connected to the low-pressure side outlet of the first counter-current heat exchanger 47, and the low-pressure side outlet of the second counter-current heat exchanger 48 is connected to the suction valve 413. The second counter-current heat exchanger 48 performs counter-current heat exchange between the high-pressure fluid pipeline 43 and the low-pressure fluid pipeline 44, recovering the cooling capacity of the returning refrigerant, further pre-cooling the high-pressure refrigerant, and improving system energy efficiency.

[0067] In summary, the refrigeration system with recoverable expansion work provided by the present invention has the following beneficial effects: 1. High energy efficiency: The expansion work of the regenerative refrigeration unit 2 can be converted into the compression power of the compression refrigeration unit 1 or the refrigerant circulation unit 4, which can reduce the external energy input of the refrigeration system, improve the energy utilization efficiency of the refrigeration system, and avoid the loss of expansion work directly dissipated in traditional schemes. In addition, when the compression refrigeration unit 1 is a JT throttling refrigeration unit and the regenerative refrigeration unit 2 is a thermoacoustic refrigerator, the thermoacoustic refrigerator can pre-cool the high-pressure refrigerant in the JT throttling refrigeration unit to a temperature range of 10-30K, so that the JT throttling refrigeration process can be carried out under optimal conditions, which can improve the overall thermodynamic efficiency of the system.

[0068] 2. High integration: By coupling the expansion piston 27 of the regenerative refrigeration unit 2 and the fluid pump piston 415 of the compression refrigeration unit 1 or the refrigerant circulation unit 4 into one unit, the fluid pump piston 415 and the expansion piston 27 slide synchronously, so that the cooling output function and the expansion sound power output function of the regenerative refrigeration unit 2 can be used at the same time. The regenerative refrigeration unit 2 serves as both the precooling stage of the compression refrigeration unit 1 or the refrigerant circulation unit 4 and the drive source of the compressor in the compression refrigeration unit 1 or the fluid pump in the refrigerant circulation unit 4. The compression refrigeration unit 1 does not need to be equipped with a separate compressor or the refrigerant circulation unit 4 does not need to be equipped with a separate fluid pump, so as to realize the integrated integration of precooling and compression functions. The system structure is compact and the volume and weight are significantly reduced.

[0069] 3. High reliability: When the regenerative refrigeration unit 2 is a thermoacoustic refrigerator or a pulse tube refrigerator, the cold end of the entire system has no mechanical moving parts. The fluid pump piston 415 or expansion piston 27 is designed to slide freely between the pressure wave transmission pipe 25 and the compression chamber A of the compressor. There are no mechanical connecting rods or rotating parts. The fluid pump piston 415 and expansion piston 27 move freely under the action of expansion work, avoiding mechanical friction and wear. In addition, the thermoacoustic refrigerator or pulse tube refrigerator itself has no moving parts, which makes the entire system have extremely high reliability and ultra-long life. It is particularly suitable for scientific and technological fields that require ultra-low temperature refrigeration, such as quantum computing, superconducting magnets, space exploration, and basic physics research.

[0070] 4. High-frequency operation and miniaturization: The system operates at frequencies as high as 50-300Hz, which is much higher than that of traditional GM refrigerators (1-2Hz) and Stirling refrigerators (typical value 30-60Hz). High-frequency operation allows for a significant reduction in the size of heat exchange components and pipelines, which is conducive to the miniaturization and weight reduction of various devices in the refrigeration system, meeting the application requirements of quantum computing and other applications with strict size and weight restrictions.

[0071] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A refrigeration system capable of recovering expansion work, characterized in that, include: A compression refrigeration unit includes a compressor, a high-pressure gas pipeline, a pre-cooling section heat exchanger, an expansion device, a cold-end heat exchanger, and a low-pressure gas pipeline. The expansion device is located on the high-pressure gas pipeline between the cold-end heat exchanger and the pre-cooling section heat exchanger. The compressor includes a compression chamber A and a compression piston that slides within the compression chamber A. The compression chamber A is connected to the high-pressure gas pipeline via an exhaust valve, and the low-pressure gas pipeline is connected to the compression chamber A via an intake valve. The gaseous refrigerant in the compression chamber A is pressurized by the compressor and flows to the pre-cooling section heat exchanger via the exhaust valve and the high-pressure gas pipeline. After being pre-cooled by the pre-cooling section heat exchanger, the high-pressure refrigerant expands through the expansion device to generate cooling capacity. The refrigerant passing through the cold-end heat exchanger flows back to the compression chamber A via the low-pressure gas pipeline and the intake valve. By coordinating the timing of the exhaust valve, the intake valve, and the movement of the compression piston, the intermittent compression of the gaseous refrigerant in the compression chamber A by the reciprocating motion of the compression piston is converted into a continuous high-pressure refrigerant output flowing to the high-pressure gas pipeline. A regenerative refrigeration unit includes a pressure wave generator for generating pressure fluctuations and a heat exchanger, a regenerator, a heat absorber, and a pressure wave transmission pipe connected in sequence along the direction of pressure wave energy propagation. The room temperature end of the pressure wave transmission pipe is provided with a sliding expansion piston. The heat absorber pre-cools the refrigerant in the heat exchanger of the pre-cooling section. The compression piston and expansion piston are coupled as one unit and slide within the compression chamber A to compress the gaseous refrigerant within the compression chamber A, so that the expansion work of the expansion piston is recovered as mechanical work to drive the movement of the compression piston.

2. The refrigeration system with recoverable expansion work according to claim 1, characterized in that, The compressor further includes a drive device that provides motion power to the combination of the compression piston and the expansion piston; the drive device is an electromagnetic drive device or a mechanical drive device; the refrigeration system includes a phase coordination control system, which controls the motion phase of the expansion piston and the piston of the pressure wave generator, so that the regenerative refrigeration unit generates a sufficient refrigeration effect.

3. The refrigeration system with recoverable expansion work according to claim 2, characterized in that, The driving device is a first electromagnetic driving device; a pair of the first electromagnetic driving devices drive the compression piston to reciprocate within the compression chamber A by switching on an alternating current.

4. The refrigeration system with recoverable expansion work according to claim 3, characterized in that, The pressure wave generator includes a compression chamber B, a piston sliding inside the compression chamber B, and a pair of second electromagnetic drive devices located outside the compression chamber B. The pair of second electromagnetic drive devices drive the piston of the pressure wave generator to reciprocate within the compression chamber B by switching on an alternating current. The phase coordination control system controls the movement phase of the expansion piston and the piston of the pressure wave generator, converting the expansion work generated by the regenerative refrigeration unit into mechanical work that drives the reciprocating motion of the compression piston.

5. The refrigeration system with recoverable expansion work according to claim 1, characterized in that, The regenerative refrigeration unit is a regenerative refrigeration machine with an expansion chamber, which is a pulse tube refrigeration machine, a Stirling refrigeration machine, or a thermoacoustic refrigeration machine.

6. The refrigeration system with recoverable expansion work according to claim 5, characterized in that, The regenerative refrigeration unit is a pulse tube refrigeration machine, the pressure wave transmission tube is a pulse tube, and the expansion piston slides against the inner wall of the room temperature end of the pulse tube.

7. The refrigeration system with recoverable expansion work according to claim 6, characterized in that, The pressure wave generator has two sets, and the pistons of the two sets of pressure wave generators move towards each other and are arranged opposite each other. The pistons of the two sets of pressure wave generators together form a compression chamber B. The volume swept by the piston movement of the two sets of pressure wave generators is doubled, and the vibrations caused by the piston movement of the two sets of pressure wave generators cancel each other out.

8. The refrigeration system with recoverable expansion work according to claim 7, characterized in that, The compressor has two sets, and the compression pistons of the two sets of compressors move towards each other and are positioned opposite each other. The two sets of compression pistons together form the compression chamber A of the compressor. The volume swept by the movement of the two sets of compression pistons is doubled, and the vibrations caused by the movement of the two sets of compression pistons cancel each other out.

9. The refrigeration system with recoverable expansion work according to claim 8, characterized in that, The two sets of compressors are arranged in parallel or in series. When the two sets of compressors are arranged in parallel, the two sets of compressors provide high-pressure gas with the same pressure ratio to the compression refrigeration unit. When the two sets of compressors are arranged in series, the high-pressure gas provided by the upper stage compressor is compressed twice by the lower stage compressor and then provided to the compression refrigeration unit to output high-pressure gas with a higher compression ratio.

10. The refrigeration system with recoverable expansion work according to claim 1, characterized in that, The pressure wave generator is a thermoacoustic engine or a loudspeaker.

11. The refrigeration system with recoverable expansion work according to claim 1, characterized in that, The compression refrigeration unit is a JT throttling refrigeration unit, which also includes a JT counter-current heat exchanger. The high-pressure side inlet of the JT counter-current heat exchanger is connected to the cold end outlet of the pre-cooling section heat exchanger. The high-pressure side outlet of the JT counter-current heat exchanger is connected to the low-pressure side inlet of the JT counter-current heat exchanger via the expansion device and the cold end heat exchanger. The low-pressure side outlet of the JT counter-current heat exchanger is connected to the suction valve of the compressor. The high-pressure refrigerant in the high-pressure gas pipeline is pre-cooled by the pre-cooling section heat exchanger and the JT counter-current heat exchanger in sequence and then flows to the expansion device for throttling expansion. It provides cooling capacity to the load at the cold end heat exchanger.

12. The refrigeration system with recoverable expansion work according to claim 11, characterized in that, The compression refrigeration unit also includes a counter-current heat exchanger. The high-pressure side inlet of the counter-current heat exchanger is connected to the exhaust valve, the high-pressure side outlet of the counter-current heat exchanger is connected to the hot end inlet of the pre-cooling section heat exchanger, the low-pressure side inlet of the counter-current heat exchanger is connected to the low-pressure side outlet of the JT counter-current heat exchanger, and the low-pressure side outlet of the counter-current heat exchanger is connected to the suction valve.

13. The refrigeration system with recoverable expansion work according to claim 1, characterized in that, The expansion device is a throttling valve or an expander. The high-pressure refrigerant in the high-pressure gas pipeline is pre-cooled by the heat exchanger in the pre-cooling section and then expanded by the throttling valve or expander.

14. A refrigeration system capable of recovering expansion work, characterized in that, include: The refrigerant circulation unit includes a fluid pump, a high-pressure fluid pipeline, a pre-cooling section heat exchanger, a cold-end heat exchanger, and a low-pressure fluid pipeline. The fluid pump includes a pump cylinder and a fluid pump piston sliding within the pump cylinder. The pump cylinder is connected to the high-pressure fluid pipeline via a discharge valve, and the low-pressure fluid pipeline is connected to the pump cylinder via a suction valve. The refrigerant in the pump cylinder is pressurized by the fluid pump and flows to the pre-cooling section heat exchanger via the discharge valve and the high-pressure fluid pipeline. After being pre-cooled by the pre-cooling section heat exchanger, the high-pressure refrigerant flows to the cold-end heat exchanger to cool the heat load. The refrigerant after passing through the cold-end heat exchanger flows back to the pump cylinder via the low-pressure fluid pipeline and the suction valve. By coordinating the timing of the discharge valve, the suction valve, and the movement of the fluid pump piston, the intermittent compression of the refrigerant in the pump cylinder by the reciprocating motion of the fluid pump piston is converted into a continuous high-pressure refrigerant output to the high-pressure fluid pipeline. The regenerative refrigeration unit includes a pressure wave generator for generating pressure fluctuations and a heat exchanger, a regenerator, a heat absorber, and a pressure wave transmission pipe connected in sequence along the direction of pressure wave energy propagation. The room temperature end of the pressure wave transmission pipe is provided with a sliding expansion piston. The heat absorber acts as a cold head to pre-cool the refrigerant in the heat exchanger of the pre-cooling section. The fluid pump piston and the expansion piston are coupled together and slide within the pump cylinder to pressurize the coolant within the pump cylinder, so that the expansion work of the expansion piston is recovered as mechanical work to drive the fluid pump piston.

15. The refrigeration system with recoverable expansion work according to claim 14, characterized in that, The fluid pump further includes a drive device that provides motion power to the combination of the fluid pump piston of the refrigerant circulation unit and the expansion piston of the regenerative refrigeration unit; the drive device is an electromagnetic drive device or a mechanical drive device; the refrigeration system includes a phase coordination control system, which controls the motion phase of the expansion piston and the piston of the pressure wave generator, so that the regenerative refrigeration unit generates a sufficient cooling effect.

16. The refrigeration system with recoverable expansion work according to claim 15, characterized in that, The driving device is a first electromagnetic driving device; a pair of the first electromagnetic driving devices drive the fluid pump piston to reciprocate within the pump cylinder by switching on an alternating current.

17. The refrigeration system with recoverable expansion work according to claim 16, characterized in that, The pressure wave generator includes a compression chamber B, a piston sliding inside the compression chamber B, and a pair of second electromagnetic drive devices located outside the compression chamber B. The pair of second electromagnetic drive devices drive the piston of the pressure wave generator to reciprocate within the compression chamber B by switching on an alternating current. The phase coordination control system controls the movement phase of the expansion piston and the piston of the pressure wave generator, converting the expansion work generated by the regenerative refrigeration unit into mechanical work that drives the reciprocating motion of the fluid pump piston.

18. The refrigeration system with recoverable expansion work according to claim 14, characterized in that, The regenerative refrigeration unit is a regenerative refrigeration machine with an expansion chamber, which is a pulse tube refrigeration machine, a Stirling refrigeration machine, or a thermoacoustic refrigeration machine.

19. The refrigeration system with recoverable expansion work according to claim 18, characterized in that, The regenerative refrigeration unit is a pulse tube refrigeration machine, the pressure wave transmission tube is a pulse tube, and the expansion piston slides against the inner wall of the room temperature end of the pulse tube.

20. The refrigeration system with recoverable expansion work according to claim 19, characterized in that, The pressure wave generator has two sets, and the pistons of the two sets of pressure wave generators move towards each other and are arranged opposite each other. The pistons of the two sets of pressure wave generators together form a compression chamber B. The volume swept by the piston movement of the two sets of pressure wave generators is doubled, and the vibrations caused by the piston movement of the two sets of pressure wave generators cancel each other out.

21. The refrigeration system with recoverable expansion work according to claim 20, characterized in that, The fluid pump has two sets, and the pistons of the two sets of fluid pumps move towards each other and are arranged opposite each other. The pistons of the two sets of fluid pumps together form the pump cylinder of the fluid pump. The volume swept by the movement of the pistons of the two sets of fluid pumps is doubled, and the vibrations caused by the movement of the pistons of the two sets of fluid pumps cancel each other out.

22. The refrigeration system with recoverable expansion work according to claim 21, characterized in that, The two sets of fluid pumps are arranged in parallel or in series. When the two sets of fluid pumps are arranged in parallel, the two sets of fluid pumps provide the refrigerant circulation unit with the same high-pressure refrigerant. When the two sets of fluid pumps are arranged in series, the high-pressure refrigerant provided by the upper-level fluid pump is pressurized again by the lower-level fluid pump and then provided to the refrigerant circulation unit, resulting in a higher output pressure of high-pressure refrigerant.

23. The refrigeration system with recoverable expansion work according to claim 14, characterized in that, The refrigerant circulation unit further includes a first counter-current heat exchanger. The high-pressure side inlet of the first counter-current heat exchanger is connected to the cold end outlet of the pre-cooling section heat exchanger. The high-pressure side outlet of the first counter-current heat exchanger is connected to the low-pressure side inlet of the first counter-current heat exchanger via the cold end heat exchanger. The low-pressure side outlet of the first counter-current heat exchanger is connected to the suction valve of the fluid pump. The high-pressure refrigerant in the high-pressure fluid pipeline flows to the cold end heat exchanger after being pre-cooled by the pre-cooling section heat exchanger, where it provides cooling capacity to the load.

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