CN106500385B - Liquid piston power recovery type pulse tube refrigeration system and application of liquid piston in pulse tube refrigeration system - Google Patents

Abstract

The invention discloses a liquid piston power recovery type pulse tube refrigerating system, which comprises a pressure wave generator, a room temperature end heat exchanger, a cold accumulator, a cold end heat exchanger, a pulse tube hot end heat exchanger and a phase modulation device which are sequentially connected, wherein: the outlet of the phase modulation device is connected with a pulse tube hot end heat exchanger or a pipeline between a pressure wave generator and a room temperature end heat exchanger, and a liquid piston is arranged in the phase modulation device. In the invention, the liquid piston is arranged in the phase modulation device of the pulse tube refrigerating system, so that the phase of the refrigerating system can be adjusted, and the work can be recovered.

Description

Liquid Piston Work Recovery Pulse Tube Refrigeration System and Application of Liquid Piston in it

technical field

The present invention relates to a pulse tube refrigeration device. More specifically, it relates to a liquid piston work recovery type pulse tube refrigeration system using a liquid piston for work recovery and the application of the liquid piston therein.

Background technique

The pulse tube refrigerator was first invented by Gifford and Longswoth in the United States. It consists of a regenerator, a pulse tube, a hot-end heat exchanger, a cold-end heat exchanger, and a phase adjustment device. Since the refrigerator does not move at low temperatures The components avoid the problems of sealing, wear and vibration at low temperature, so they have the advantages of compact structure, low vibration, long life, etc., and have a very wide range of applications in space technology, superconducting electronics, infrared detection, low temperature biomedicine, etc. Application prospects.

Although the attractiveness of the pulse tube refrigerator is that it eliminates the moving part in the low temperature region - the displacer, it must add an effective regulator to compensate for the function of the eliminated displacer, so the system becomes complicated, especially The existence of the phase-modified gas store makes the volume of the system larger. Moreover, while improving the phase relationship between the pressure and the volumetric flow rate, the phasing device also consumes part of the sound power, and does not make full use of the sound power entering the system. Therefore, for pulse tube refrigerators that do not use work recovery devices , and its cycle efficiency limit is T _C /T _H , which is lower than the limit cycle efficiency T _C /(T _H -T _C ) of the ideal Carnot refrigeration cycle.

In recent years, pulse tube refrigerators have developed rapidly in the liquid nitrogen temperature range and the temperature range below 10K. Among them, the main development direction of the liquid nitrogen temperature zone is the Stirling-type pulse tube refrigerator with large cooling capacity, and the main development direction of the temperature zone below 10K is the GM low-frequency pulse tube refrigerator and the multi-stage Stirling-type pulse tube refrigerator. To obtain a large cooling capacity in the liquid nitrogen temperature zone and obtain an extremely low temperature below 10K, it is necessary to increase the input power of the pulse tube refrigerator, and the sound power consumed in the phase modulation device is also significantly increased, making the system efficiency low. In addition, for low-frequency pulse tube refrigerators below 10K, the required phase modulation angle is also significantly increased, and the phase modulation system also faces the problem of insufficient phase modulation capability. Therefore, in view of the main problems in the development of pulse tube refrigerators, a feasible method is to explore power recovery and phase modulation pulse tube refrigerators, which can simultaneously solve the problems of sound power dissipation and insufficient phase modulation capabilities.

In the existing power recovery phase modulation pulse tube refrigerator, the good capacitive reactance and inductive reactance effect of the adsorber has been used to replace the gas storehouse and inertia tube in the traditional pulse tube refrigerator, so as to achieve the minimum required for the refrigerator to work. Good phase shift, but this device cannot solve the problem of the dissipation of sound work in the pulse tube in the phase modulation device, so the efficiency of the refrigerator is low; there are also pressure fluctuations that rely on the inertia of the moving mass module, inertia tube or valve resistance to form a phase lead The impedance boundary adjustment of the volumetric flow rate increases the ability of phase modulation, but the system still includes devices such as small hole air reservoirs, the system is complex and the sound work consumed by the phase modulation device has not been completely eliminated; and by setting the vessel to 1/ The 4-wavelength long neck tube adjusts the phase between the internal pressure wave and the volume flow of the refrigerator, eliminating the need for the original passive or active phase adjustment device. But this method requires that the long-necked tube has a wavelength of 1/4, and the temperature, frequency and pressure of the refrigerator all affect the wavelength, making the invention more difficult to realize.

Based on the above deficiencies, it is necessary to provide a pulse tube refrigeration system with good work recovery effect, simple and compact structure, strong phase modulation capability and dynamic adjustment of the phase of the pulse tube.

Contents of the invention

The first object of the present invention is to provide a liquid piston work recovery type pulse tube refrigeration system. By providing a liquid piston in the phase adjustment device, the adjustment of the phase of the refrigeration system and the work (for example, sound work) are realized at the same time. At the same time, it also makes the system more compact, convenient to use and efficient in refrigeration.

The second object of the present invention is to provide the application of the above-mentioned liquid piston in the work recovery of the pulse tube refrigeration system.

In order to achieve the above-mentioned first object, the present invention adopts the following technical solutions:

A liquid piston work recovery type pulse tube refrigeration system, which includes a pressure wave generator, a heat exchanger at room temperature end, a cold storage device, a heat exchanger at cold end, a pulse tube, a heat exchanger at the hot end of pulse tube and a heat exchanger connected in sequence Phase device, the outlet of the phase modulation device is connected to the pipeline between the heat exchanger at the hot end of the pulse tube or the pressure wave generator and the heat exchanger at the room temperature end, and a liquid piston is arranged in the phase modulation device.

Preferably, the liquid used by the liquid piston is one of room temperature liquid metal, mercury, water and alcohol. More preferably, the liquid used in the liquid piston is room temperature liquid metal or mercury. For example, the liquid metal at room temperature may be gallium indium alloy, gallium indium tin alloy, or the like. The aforementioned room temperature liquid metal or mercury has a high density, and under the same volume, the inertial force generated by the reciprocating oscillation is also large. Combined with the compression and expansion effect on the gas, it can effectively adjust the phase in the pulse tube refrigeration system and realize the recovery of work; at the same time, these Liquids do not evaporate and contaminate the working fluid; in addition, the low viscosity of these liquids minimizes flow resistance accordingly. More preferably, the liquid used by the liquid piston is mercury.

Preferably, the phasing device is one of a U-shaped tube, a straight tube, a helical tube and an L-shaped tube with a liquid piston inside. Selecting the tubular phase-modulating device of these several shapes can realize phase adjustment more effectively; more preferably, the phase-modulating device is a U-shaped tube with a liquid piston inside. At this time, the phase modulation device not only has a good phase modulation effect but also can effectively prevent power loss.

Preferably, a resistance adjustment device is provided on the pipeline connecting the outlet of the phase adjustment device with the heat exchanger at the hot end of the pulse tube or the pipeline between the pressure wave generator and the heat exchanger at the room temperature end. By adjusting the opening of the resistance adjustment device, the stiffness of the gas working medium at the outlet side of the phase modulation device can be adjusted conveniently, so that the recovery of work and the effect of phase adjustment can reach the optimal value. Further, the more preferred resistance adjusting device may be selected from, but not limited to, one of a regulating valve, a capillary and a nozzle.

The pressure wave generator in the present invention can be a low frequency generator or a high frequency generator. More preferably, the pressure wave generator can be one of GM type low frequency generator, VM type low frequency generator, Stirling type high frequency generator and thermoacoustic type generator.

Preferably, the heat exchanger at the hot end of the pulse tube is connected to the phase adjustment device through a long neck tube, so as to further facilitate phase adjustment; the heat exchanger at the cold end is connected to the pulse tube through a cold head connecting pipe.

Preferably, the gas working fluid used in the refrigeration system is helium.

Preferably, when the liquid is water or ethanol, an isolation structure is provided between the gas working medium in the refrigeration system and the water or ethanol; preferably, the isolation structure is a membrane structure.

In the present invention, the structure of the refrigeration system is preferably one of linear, U-shaped and coaxial; the refrigeration system is a single-stage pulse-tube refrigeration system or a two-stage pulse-tube refrigeration system.

To achieve the above-mentioned second object, the present invention also provides the application of the above-mentioned piston liquid in the work recovery of the pulse tube refrigeration system.

Setting the above-mentioned liquid piston in the phase adjustment device not only realizes the adjustment of the phase in the pulse tube refrigeration system, but also realizes the recovery of work.

The beneficial effects of the present invention are as follows:

In the present invention, phase adjustment is carried out by installing a liquid piston in the phase adjustment device, making full use of the inertial force generated by the reciprocating oscillation of the high-density liquid and the compression and expansion effect on the gas, adjusting the phase relationship and recovery work in the refrigeration system, so that the system The efficiency is more efficient, compact, and convenient to use; in addition, because the liquid piston phase modulation does not introduce any other mechanical parts, compared with other active phase modulation methods, there is no problem such as wear and tear, and the life of the refrigerator is greatly improved; In addition, The setting of the liquid piston can also effectively avoid the direct flow of Gedeon caused by two-way air intake.

In the present invention, the inertial force generated during the reciprocating motion of the liquid is fully utilized, and the loss of work by the liquid is low, so that the liquid piston can effectively recover work; it can not only provide a suitable phase relationship for the cold accumulator, but also make the system The ultimate refrigeration efficiency is increased to the ultimate cycle efficiency of the Carnot refrigeration cycle.

The arrangement of the liquid piston in the phase modulation device of the present invention eliminates structures such as small hole-gas storage, long-diameter tube-gas storage, and two-way air intake, making the structure of the pulse tube refrigeration system more compact and convenient to use, and the two-way air intake structure The removal effectively avoids the influence of Gedeon DC.

The present invention can also well solve the problem of insufficient phase modulation in low-frequency pulse tube refrigerators and pulse tube refrigerators with a small cooling capacity below 40K.

Description of drawings

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

Fig. 1 shows the structure of a liquid piston work recovery type pulse tube refrigeration system according to Embodiment 1 of the present invention.

Figures 2 a to d show the oscillation process of the liquid in the U-shaped tube in the liquid piston work recovery type pulse tube refrigeration system according to Embodiment 1 of the present invention.

Fig. 3 shows the structure of the liquid piston work recovery type pulse tube refrigeration system according to Embodiment 2 of the present invention.

Detailed ways

In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.

Example 1

Figure 1 shows the structure of the liquid piston work recovery type pulse tube refrigeration system of Embodiment 1 of the present invention: it includes pressure wave generators 1 connected in sequence, for example, VM type low frequency generators, room temperature end heat exchangers 2 , regenerator 3, cold end heat exchanger 4, pulse tube 6, pulse tube hot end heat exchanger 7 and phase modulation device 9. Among them, the pressure wave generator 1 is connected to the heat exchanger 2 at the room temperature end through a connecting pipe, the heat exchanger 4 at the cold end is connected to the pulse tube 6 through the cold head connecting pipe 5, and the heat exchanger 7 at the hot end of the pulse tube is connected to the phase modulation device 9 The inlet of (U-shaped tube filled with liquid mercury) is connected through a connecting pipeline, and the outlet of the phasing device 9 is communicated with the hot end heat exchanger 7 of the pulse tube through the pipeline, and the resistance regulating device regulating valve 8 is provided on the pipeline. The gas working medium in the pulse tube refrigeration system is helium.

The working process of the above-mentioned liquid piston work recovery type pulse tube refrigeration system is as follows: the sound work emitted from the pressure wave generator 1 enters the room temperature side heat exchanger 2, the cold storage device 3, the cold side heat exchanger 4, the pulse tube 6 and the pulse tube refrigeration system successively. The heat exchanger 7 at the hot end of the tube generates cold energy at the heat exchanger 4 at the cold end. The sound work from the heat exchanger 7 at the hot end of the pulse tube enters the U-shaped pipe from the inlet of the U-shaped pipe through the connecting pipeline. Driven by the pressure wave formed by the sound work, the mercury in the U-shaped pipe reciprocates in the U-shaped pipe. movement, forming a liquid piston. In one pressure wave cycle, the schematic diagram of the oscillation process of the liquid is shown in Fig. 2a-d: With the increase of the pressure wave, when the pressure at the inlet end of the U-shaped pipe increases from the equilibrium pressure to the maximum pressure, the inlet side of the U-shaped pipe (left side) the liquid level drops, the outlet side (right side) liquid level rises, and the left and right liquid levels form a height difference H1(a), and at the same time, the gas working medium helium above the right side liquid level is compressed, thus The time work is stored in the phasing device by the gravitational potential energy of the liquid and the compression energy of the gas working medium in the U-shaped tube on the right; as the pressure on the left side drops from the highest value to the average pressure, the energy stored in the U-shaped tube is released (b ), the work is recovered into the vessel; as the pressure on the left side further drops to the minimum pressure, the liquid level on the right side in the U-shaped tube drops, the liquid level on the left side rises, and the left and right liquid levels form a height difference H2(c). At this time, The gas working medium above the liquid surface on the right side expands and continues to do work on the vessel; when the pressure rises from the minimum pressure to the average pressure (d), the work stored in the vessel is released into the U-shaped tube. Thereby completing a pressure wave cycle and realizing the recovery of work. Furthermore, the phase of the vessel outlet pressure wave and mass flow can be adjusted by the above-mentioned inertial mass of the liquid piston. Among them, during the working process of the pulse tube refrigeration system, by controlling the opening of the regulating valve, the stiffness of the gas working medium above the liquid on the right side of the U-shaped tube can be easily adjusted, so that the work recovery and phase adjustment can reach the optimal value.

Example 2

Figure 3 shows the structure of the liquid piston work recovery type pulse tube refrigeration system in Embodiment 2 of the present invention, which is basically the same as in Embodiment 1, the only difference being that the outlet of the phasing device 9 passes through the pipeline and the pressure wave The pipeline between the generator 1 and the heat exchanger at the room temperature end is connected, and a resistance adjustment device, such as a regulating valve 8, is installed on the pipeline. The liquid in the U-shaped tube is gallium-indium alloy, and other conditions remain unchanged. Thereby realizing the recovery of work and the adjustment of the phase of this refrigeration system. During the working process of the pulse tube refrigeration system, controlling the opening of the regulating valve 8 can conveniently adjust the stiffness of the gas working medium above the liquid on the right side of the U-shaped tube, so that the work recovery and phase adjustment can reach the optimal value, and through Controlling the regulating valve 8 can also promote the adjustment of the vessel phase more obviously.

Apparently, the above-mentioned embodiments of the present invention are only examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those of ordinary skill in the art can also make It is impossible to exhaustively list all the implementation modes here, and any obvious changes or changes derived from the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims (8)

1. A liquid piston work recovery type pulse tube refrigeration system, which includes a pressure wave generator, a room temperature end heat exchanger, a cold storage device, a cold end heat exchanger, a pulse tube, and a pulse tube hot end heat exchanger connected in sequence And the phasing device, characterized in that: the outlet of the phasing device is connected to the pipeline between the heat exchanger at the hot end of the pulse tube or the pressure wave generator and the heat exchanger at the room temperature end, and the liquid is arranged in the phasing device Piston; the liquid used in the liquid piston is one of room temperature liquid metal, water and alcohol; wherein, the room temperature liquid metal is selected from one of gallium indium alloy, gallium indium tin alloy and mercury. 2. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: the phase modulation device is one of a U-shaped tube, a straight tube, a spiral tube, and an L-shaped tube with a liquid piston inside. kind. 3. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: between the outlet of the phase modulation device and the heat exchanger at the hot end of the pulse tube or the pressure wave generator and the heat exchanger at the room temperature end There is a resistance adjustment device on the pipeline connected by the pipeline between them. 4 . The liquid piston work recovery type pulse tube refrigeration system according to claim 3 , wherein the resistance adjusting device is one of a regulating valve, a capillary tube and a nozzle. 5. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: the pressure wave generator is a GM type low frequency generator, a VM type low frequency generator, or a Stirling type high frequency generator and one of the thermoacoustic generators. 6. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: the gas working medium used in the refrigeration system is helium. 7. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: when the liquid is water or mercury, an isolation structure is provided between the gas working medium in the refrigeration system and the water or mercury; The isolation structure is a membrane structure. 8. The liquid piston work recovery type pulse tube refrigeration system according to claim 1, characterized in that: the structure of the refrigeration system is one of linear, U-shaped and coaxial; the refrigeration system is a single One-stage pulse tube cooling system or two-stage pulse tube cooling system.