Pulse tube refrigerator adopting index curve structure for phase adjustment

Abstract

The invention discloses a pulse tube refrigerator adopting an index curve structure for phase adjustment. The device comprises a compressor, a precooler, a heat regenerator, a cold-end heat exchanger, a pulse tube, a hot-end heat exchanger, a reducing cavity, an adjusting tube and a phase modulation device which are communicated in sequence. The phase modulation device comprises a plane cover plate, a curved side plate, an opening sealing plate and a plane bottom plate which are enclosed to form a phase modulation cavity, and two adjusting partition plates are arranged in the phase modulation cavity. The two plane cover plates are the same in shape and are arranged in parallel, the whole plane cover plates are in a horn shape, and two contour lines of the side edges are symmetrical, smooth and continuous index curves. According to the inertia tube structure, the rectangular flow channel with the smoothly-expanded width is adopted, acoustic power transmission is easy, flow resistance is reduced, air pressure drop is reduced, and the efficiency of a refrigerating machine is improved. The problem that the phase difference between pressure waves and mass flow is too large is effectively solved, the phase modulation effect is improved, and structural parameters can be flexibly adjusted to expand the expansibility.

Description

Technical Field

[0001] This invention belongs to the field of high-frequency pulse tube cryogenic refrigerators, and specifically relates to a pulse tube refrigerator that uses an exponential curve structure for phase adjustment. Background Technology

[0002] High-frequency pulse tube refrigerators, due to their outstanding advantages such as no moving parts in the low-temperature region, high reliability, low vibration, and long lifespan, have irreplaceable application value in defense and cutting-edge scientific fields such as space exploration, infrared guidance, and superconducting electronics. Their core performance lies in the phase relationship between the pressure wave and mass flow within the regenerator; optimal phase is key to achieving high cooling efficiency. Currently, the most commonly used phase-adjusting mechanism in Stirling pulse tube refrigerators is the "inertial tube-gas reservoir" combination. In this system, the inertial tube utilizes the inertia (inductive reactance) of the alternating flow of gas to adjust the phase, while the gas reservoir provides a capacitive reactance element. Although this structure is an improvement over earlier designs, it suffers from two inherent and fundamental defects that severely impact performance. To address the problem of insufficient phase-adjusting flexibility, existing technologies have adopted schemes using parallel multi-path inertial tubes (such as patent CN201710116594.6). This scheme provides discrete phase-adjusting capability by switching different branches, thus expanding the phase-adjusting range to some extent. However, it does not solve the fundamental problem of acoustic power loss because the connection between each branch inertial tube and the gas reservoir remains abrupt. Furthermore, its phase modulation is step-like and discontinuous, failing to achieve fine, stepless phase adjustment, and the system structure and control strategy are more complex. Therefore, there is an urgent need in this field for a novel phase modulation mechanism that can fundamentally eliminate acoustic power loss at the connection between the inertial tube and the gas reservoir, while possessing a wide-range, continuous, and adjustable phase adjustment capability to meet the high-performance requirements of pulse tube refrigerators in complex application scenarios.

[0003] Stirling-type pulse tube refrigerators typically employ an inertial tube and a gas reservoir as the phase-adjusting mechanism, and circuit simulations are used to analyze the inertial tube. The phase-adjusting capability of the inertial tube is highly sensitive to its geometric parameters. Analysis and experiments show that the inertial tube can adjust the phase over a wide range, making it suitable for use in high-power pulse tube refrigerators, and also meeting appropriate phase-adjusting requirements in smaller pulse tube refrigerators. The gas inside the inertial tube flows alternately; through circuit analogy, the gas flow resistance can be represented as a drag characteristic, the inertia of the working fluid manifests as inductive reactance, and the internal air volume manifests as capacitive reactance.

[0004] The impedance of the inertial tube is expressed as: , The Reynolds number represents the flow of the working fluid inside the pipe. Indicates mass flow rate. This indicates the density of the working gas. The length of the inertial tube, This is the inner diameter of the inertial tube. The inductive reactance of the inertial tube. Capacitive and resistive properties of inertial tubes Gas storage capacity resistance The total impedance of the inertial tube is expressed as: The phase angle between the inertial tube inlet mass flow and the pressure wave is: As can be seen, the phase modulation capability of an inertial tube is closely related to its impedance, capacitive reactance, and inductive reactance. However, traditional inertial tubes use a single metal tube of fixed length and diameter for phase modulation, which has low flexibility and cannot be coordinated with phase modulation when parameters such as frequency and input power change. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a pulse tube refrigerator with flexible phase adjustment, low loss, and high efficiency, which uses an exponential curve structure as the phase adjustment device.

[0006] This invention comprises a compressor, a precooler, a regenerator, a cold-end heat exchanger, a pulse tube, a hot-end heat exchanger, a shrinking chamber, and a phase-adjusting device connected in sequence. The shrinking chamber and the phase-adjusting device are connected via a regulating pipe. The high-temperature, high-pressure gas compressed by the compressor enters the regenerator after passing through the precooler. After being further cooled by the regenerator, the gas absorbs heat from the cold-end heat exchanger and then enters the pulse tube. The temperature at the hot end of the pulse tube rises, and the gas undergoes heat exchange again after passing through the hot-end heat exchanger. The gas then converges in the shrinking chamber and enters the phase-adjusting device through the regulating pipe. The regulating pipe is equipped with a regulating valve to adjust the gas flow rate.

[0007] The phase-adjusting device is a metal cavity, comprising two flat cover plates, two curved side plates, an opening sealing plate, a flat bottom plate, and two adjusting baffles. The flat cover plates, curved side plates, opening sealing plate, and flat bottom plate form a phase-adjusting cavity. An adjusting pipe is located at the end of the flat bottom plate, and the adjusting baffles are located inside the phase-adjusting cavity to adjust the flow resistance of the inertial pipe section and the equivalent volume of the gas storage section.

[0008] The two planar cover plates are identical in shape and arranged parallel to each other; the planar cover plates are generally trumpet-shaped, with two symmetrical, smooth, continuous curves on their sides, and these curves are exponential curves. and curve , It is the expansion constant. 0.009~0.011, This is the width adjustment factor. 1-2; Width variation of the flat cover plate , The length variable is the distance from the base plate. This is the starting width of the entrance. 2-6mm, total length of the flat cover plate 400~600mm; the overall thickness of the phase adjustment device is 15~30mm.

[0009] This invention, based on the characteristics of a horn-shaped structure, changes the structure of the inertial tube from a traditional fixed-diameter metal tube to a rectangular flow channel with a smoothly expanding width. Furthermore, the wide end of the flow channel is sealed as a gas reservoir, solving the problem of acoustic power loss caused by the separation of the inertial tube and gas reservoir in traditional pulse tube refrigerators. The horn-shaped structure has smooth streamlines, facilitating acoustic power transmission, reducing flow resistance, reducing air pressure drop, and improving refrigerator efficiency. The transition of the phase-adjusting device is natural and harmonious, which is very beneficial for the amplification and attenuation of acoustic power within the structure. The gas exiting the pulse tube hot-end heat exchanger first enters the small-end inlet of the structure; the high pressure at the inlet of the converging cavity is conducive to gas flow. Using a horn-shaped structure as the inertial tube and gas reservoir for phase adjustment in the pulse tube refrigerator results in high energy utilization, no special requirements on other components of the pulse tube refrigerator, effectively solves the problem of excessive phase difference between pressure waves and mass flow, improves the phase-adjusting effect, enhances the overall cooling capacity of the refrigerator, and allows for flexible adjustment of structural parameters, giving it great scalability. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0011] Figure 2 This is a schematic diagram of the phase adjustment device.

[0012] Figure 3 This is a schematic diagram of the phase adjustment device.

[0013] Figure 4 This is a schematic diagram of the planar cover plate in the embodiment;

[0014] Figure 5 This is a schematic diagram illustrating the phase modulation effect of the present invention. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] like Figure 1 As shown, the pulse tube refrigerator that uses an exponential curve structure for phase adjustment includes a compressor 1, a precooler 2, a regenerator 3, a cold end heat exchanger 4, a pulse tube 5, a hot end heat exchanger 6, a shrinking cavity 7, and a phase adjustment device 8 connected in sequence. The shrinking cavity 7 and the phase adjustment device 8 are connected through an adjustment pipe 9.

[0017] The converging cavity 7 is an inverted trumpet-shaped cavity with a smooth curved inner wall. The upper end of the converging cavity is connected to one end of the regulating pipe 9, and the other end of the regulating pipe 9 is connected to the phase adjustment device 8. The lower end of the converging cavity is connected to the hot-end heat exchanger 6. The high-temperature, high-pressure gas compressed by the compressor 1 passes through the precooler 2 and enters the regenerator 3. After being further cooled by the regenerator 3, it absorbs heat from the cold-end heat exchanger 4 and then enters the pulse tube 5. The temperature at the hot end of the pulse tube 5 increases, and the gas undergoes heat exchange again after passing through the hot-end heat exchanger 6. Afterward, it passes through the converging cavity 7 and enters the phase adjustment device 8 through the regulating pipe 9. The regulating pipe 9 is equipped with a regulating valve to adjust the gas flow rate.

[0018] like Figure 2 and 3 As shown, the phase-adjusting device 8 is a metal cavity, comprising two flat cover plates 8-1, two curved side plates 8-2, an opening sealing plate 8-3, a flat bottom plate 8-4, and two adjusting partitions 8-5. The flat cover plates 8-1, curved side plates 8-2, opening sealing plate 8-3, and flat bottom plate 8-4 form the phase-adjusting cavity. The adjusting pipe 9 is located at the end of the flat bottom plate 8-4. The phase-adjusting cavity is connected to the tapered cavity 7 through the adjusting pipe 9, thus achieving the function of phase adjustment.

[0019] Two identical planar cover plates are arranged in parallel. The planar cover plate 8-1 is generally trumpet-shaped, with two symmetrical, smooth, continuous curves along its sides. These curves are exponential curves. and curve .in, It is the expansion constant. 0.009~0.011, This is the width adjustment factor. 1-2, Width variation of the phase modulation device , The length variable is the distance from the entrance. The starting width of the entrance (i.e., the closest distance between the two curved side plates). 2-6mm. Total length of the phase adjustment device (i.e., the distance between the opening sealing plate and the flat base plate). 400–600 mm. In this embodiment… 1, 0.01, total length 500mm, starting width of the entrance 3mm, end width (i.e., the furthest distance between the two curved side plates). 300mm, flat cover plate shape as follows Figure 4 As shown. The thickness h (i.e., the distance between the two planar cover plates) of the phase adjustment device 8 is 15-30 mm, and 20 mm is used in this embodiment.

[0020] The regulating baffle 8-5 is a rectangular metal plate installed within the phase-adjusting cavity. The middle of the regulating baffle 8-5 is connected to two curved side plates via a rotating shaft, forming a flip plate. A knob is located at one end of the rotating shaft; rotating the knob flips the regulating baffle, creating two valves. One regulating baffle is located in the middle of the phase-adjusting cavity, dividing it into an inertia pipe section and a gas storage section; the other regulating baffle is located in the gas storage section.

[0021] Gas enters the funnel-shaped cavity through a regulating pipe. The flow path gradually increases from the inlet to the closed end, with the smaller section serving as the inertial tube and the larger, closed section serving as the gas reservoir. By operating the opening and closing angles of the two regulating baffles, the flow resistance of the inertial tube section and the equivalent volume of the gas reservoir section can be adjusted separately, thereby obtaining continuously adjustable phase modulation capability.

[0022] The following comparison uses the two inertial tubes in the parallel connection diagram of patent number CN201710116594.6 to compare the phase modulation performance of the horn-shaped phase modulation device in the embodiment. Figure 5 As can be seen (the dashed line in the figure is the adjustment capability curve of the inertial tube of CN201710116594.6, and the solid line is the adjustment capability curve of the horn-shaped structure in this embodiment), due to the smooth and continuous expansion characteristics of the horn-shaped flow channel and the partition design that can be adjusted in sections, a better and more flexible continuous phase adjustment capability is obtained as shown in the figure.

[0023] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pulse tube refrigerator employing an exponential curve structure for phase adjustment, comprising a compressor, a precooler, a regenerator, a cold-end heat exchanger, a pulse tube, a hot-end heat exchanger, a shrinking chamber, and a phase-adjusting device connected sequentially, wherein the shrinking chamber and the phase-adjusting device are connected via an adjusting pipe; high-temperature, high-pressure gas compressed by the compressor enters the regenerator after passing through the precooler, is further cooled by the regenerator, absorbs heat from the cold-end heat exchanger, and then enters the pulse tube, where the temperature at the hot end of the pulse tube rises. The gas then passes through the hot-end heat exchanger for further heat exchange, is collected in the shrinking chamber, and enters the phase-adjusting device through the adjusting pipe; the adjusting pipe is equipped with an adjusting valve to regulate the gas flow rate; characterized in that: The phase-adjusting device is a metal cavity, comprising two flat cover plates, two curved side plates, an opening sealing plate, a flat bottom plate, and two adjusting baffles; the flat cover plates, curved side plates, opening sealing plate, and flat bottom plate form a phase-adjusting cavity, the adjusting tube is located at the end of the flat bottom plate, and the adjusting baffles are located inside the phase-adjusting cavity; The two planar cover plates are identical in shape and arranged parallel to each other; the planar cover plates are generally trumpet-shaped, with two symmetrical, smooth, continuous curves on their sides, and these curves are exponential curves. and curve , It is the expansion constant. 0.009~0.011, This is the width adjustment factor. 1~2; Width variation of the flat cover plate , The length variable is the distance from the base plate. This is the starting width of the entrance. 2-6mm, total length of the flat cover plate 400~600mm; The adjusting baffle is a rectangular metal plate, with the middle part connected to two curved side plates via a rotating shaft to form a flip plate. A knob is provided at one end of the rotating shaft, and rotating the knob will flip the adjusting baffle. One adjusting baffle is located in the middle of the phase adjustment cavity, dividing the phase adjustment cavity into an inertial tube section and a gas storage section, and the other adjusting baffle is located in the gas storage section.

2. The pulse tube refrigerator with phase adjustment using an exponential curve structure as described in claim 1, characterized in that: The tapering cavity is an inverted trumpet-shaped cavity with a smooth curved inner wall. The upper end is narrowed and connected to one end of the regulating pipe, while the lower end is open and connected to the hot-end heat exchanger.

3. The pulse tube refrigerator with phase adjustment using an exponential curve structure as described in claim 1, characterized in that: The thickness of the phase adjustment device is 15-30 mm.

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