CN102538271A - Pulse tube refrigerator capable of restraining direct current - Google Patents

Abstract

The invention discloses a pulse tube refrigerator for suppressing direct current, which includes a pressure wave generator A and a pulse tube refrigerator B. The pulse tube refrigerator B includes a regenerator, a pulse tube, a phase modulating element and a gas storage, and the pulse tube is located in the regenerator. Inside, one end of the cold accumulator is connected to the pressure wave generator through the first connecting pipe, the other end of the cold accumulator is connected to the cold end heat exchanger of the pulse tube, and the hot end heat exchanger of the pulse tube is connected to the phase modulating element, gas The reservoirs are connected in sequence, and the back pressure chamber of the pressure wave generator is directly connected with the gas reservoir by an adjustment mechanism. The direct current suppressing pulse tube refrigerator of the present invention can suppress multiple direct currents in the pulse tube refrigerator, reduce the additional heat flow from the hot end to the cold end of the pulse tube refrigerator, thereby improving the performance of the pulse tube refrigerator and stabilizing the refrigeration performance.

Description

A Pulse Tube Refrigerator with DC Suppression

technical field

The invention relates to the technical field of refrigeration and low temperature, in particular to a pulse tube refrigerator capable of suppressing direct flow.

Background technique

Whether it is traditional industries such as gas liquefaction, separation, storage and transportation, and cryopreservation, or cutting-edge scientific research such as modern high-energy physics, condensed matter physics, space physics, and material science, all are inseparable from cryogenic technology. In the past 20 years, with the rise of modern information technology, space technology, superconducting electronics, satellite remote sensing and telemetry, cryogenic medicine and other fields, cryogenic technology has developed vigorously, and the development of small cryogenic refrigerators has also become a field of cryogenic technology research. hotspots. High-efficiency, stable, and reliable small cryogenic refrigerators can provide effective cold sources and low-temperature conditions for their related low-temperature applications.

Because the pulse tube refrigerator has no mechanical moving parts at the low temperature end, it has the advantages of small mechanical vibration, small electromagnetic interference, long life, simple structure and high reliability, so it can be used in conjunction with various devices to form small special instruments. Weapons, superconducting technology, scientific research and industry, medical equipment, mobile communication base stations and other fields have great advantages and broad application prospects.

With the continuous introduction of new structures and processes, the performance of pulse tube refrigerators has been greatly improved, and the refrigeration efficiency has reached or approached the level of Stirling refrigerators. The pulse tube refrigerator is characterized by the alternating flow of gas working medium, but there is a direct current inside the pulse tube refrigerator, that is, the mass flow transmission from the hot end to the cold end of the pulse tube refrigerator. Direct current will not only reduce the performance of the pulse tube refrigerator, but also affect the stability of its refrigeration temperature. Rayleigh flow is a kind of acoustic work flow, which is mainly formed in the gas boundary layer, which can be suppressed to a certain extent by using a conical pulse tube; the third type of direct current effect proposed by Gedeon DC and Zhou Yuan et al. in 2009 is mainly due to the interaction of working fluid It is caused by the characteristics of variable flow, the asymmetry of the structure and resistance of the refrigerator system, and the change of the physical properties of the working medium. The Gedeon direct current only exists in the two-way inlet type pulse tube refrigerator, while the third direct current generally exists in various types of pulse tube refrigerators. Since the DC effect will bring additional heat flow from the hot end to the cold end of the pulse tube refrigerator, resulting in a decrease in cooling capacity, an increase in the minimum cooling temperature, and unstable cooling temperature, it is very important to use some methods to suppress it. important. At present, asymmetric nozzles are used instead of two-way air intake to suppress Gedeon direct current, and there is no effective suppression method for the third direct current.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the invention is how to suppress multiple direct currents in the pulse tube refrigerator, thereby improving the performance of the pulse tube refrigerator.

(2) Technical solutions

In order to solve the above technical problems, a pulse tube refrigerator that suppresses direct current is provided, including a pressure wave generator and a pulse tube refrigerator. The tube is located in the cold accumulator, one end of the cold accumulator is connected with the pressure wave generator through the first connecting pipe, the other end of the cold accumulator is connected with the pulse tube cold end heat exchanger, and the pulse tube hot end heat exchanger is connected with the The phase modulating element and the gas storage are connected in sequence, and the back pressure chamber of the pressure wave generator and the gas storage are directly connected by an adjustment mechanism.

Preferably, the pressure wave generator is a linear compressor or a crankshaft compressor.

Preferably, the pulse tube refrigerator is a U-shaped, coaxial or linearly arranged single-stage pulse tube refrigerator.

Preferably, the pulse tube refrigerator is a U-shaped, coaxial, or linearly arranged multistage pulse tube refrigerator.

Preferably, the phase modulation element is a throttle valve, an inertia tube or a two-way intake valve, or any combination of the above three.

Preferably, the adjustment mechanism is a valve and/or a second connecting pipe capable of adjusting gas flow and phase.

Preferably, the valve is an asymmetric nozzle, a one-way valve, a flow valve or a combination thereof.

Preferably, the diameter of the second connecting pipe ranges from 1 mm to 5 cm.

Preferably, the second connecting pipe is a pipe of equal diameter; or the second connecting pipe includes several kinds of pipes with different diameters connected together; or the second connecting pipe is a reducing pipe whose diameter continuously changes.

Preferably, the frequency of the pulse tube refrigerator is 5Hz to 300Hz.

Preferably, the refrigeration temperature range of the pulse tube refrigerator is 273K to 1K.

(3) Beneficial effects

The direct current suppressing pulse tube refrigerator of the invention can suppress various direct currents in the pulse tube refrigerator, reduce the additional heat flow from the hot end to the cold end of the pulse tube refrigerator, thereby improving the performance of the pulse tube refrigerator and stabilizing the refrigeration performance.

Description of drawings

Fig. 1 is a schematic structural view of a pulse tube refrigerator for suppressing direct flow according to an embodiment of the present invention;

Fig. 2 is a diagram showing the results of experiments conducted using the pulse tube refrigerator of Fig. 1 for suppressing direct flow.

Among them, 1: cold storage; 2: pulse tube; 3: phase modulation element; 4: gas storage; 5: hot end heat exchanger of cold storage; 6: first connecting pipe; 7: cold end heat exchanger of pulse tube.

Detailed ways

The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

As shown in Figure 1, the present invention provides a pulse tube refrigerator that suppresses direct current, including a pressure wave generator A and a pulse tube refrigerator B, and the pulse tube refrigerator B includes a regenerator 1, a pulse tube 2, and a phase modulation element 3 and the gas storage 4, the pulse tube 2 is located in the regenerator 1, one end of the regenerator 1 is connected to the pressure wave generator A through the first connecting pipe 6, and the other end of the regenerator 1 is connected to the cold end heat exchanger 5 of the pulse tube The pulse tube hot end heat exchanger 7 is sequentially connected with the phase modulation element 3 and the gas storage 4, and the back pressure chamber of the pressure wave generator and the gas storage 4 are directly connected by an adjustment mechanism. The pressure wave generator A can be selected as a linear compressor. The pulse tube refrigerator B can be a U-shaped, coaxial or linearly arranged single-stage pulse tube refrigerator; or the pulse tube refrigerator B can be a U-shaped, coaxial, or linearly arranged multistage pulse tube refrigerator. The phase modulating element 3 is a throttle valve, an inertia tube or a two-way intake valve, or any combination of the above three. The regulating mechanism is a valve and/or a second connecting pipe capable of regulating gas flow and phase. The valves are asymmetric nozzles, check valves, flow valves or combinations thereof. The diameter of the second connecting pipe ranges from 1 mm to 5 cm. The second connecting pipe may be a pipe of equal diameter; or the second connecting pipe may comprise several kinds of pipes with different diameters connected together; or the second connecting pipe may be a reducing pipe whose diameter continuously changes. The frequency of the pulse tube refrigerator is 5Hz to 300Hz.

The regenerator in pulse tube refrigerator B is a porous medium, and gas is stored in the empty volume. Due to temperature changes and pressure fluctuations, the stored gas will be compressed and expanded, so the flow rate flowing through each section of the regenerator Not equal, the interior of the cold storage is a complex alternating flow process. Through theoretical analysis, it can be known that the Gedeon direct current and the third direct current effect are mainly caused by the characteristics of the alternating flow of the working medium, the asymmetry of the structure and resistance of the refrigerator system, and the change of the physical properties of the working medium. Symmetry is an effective means to suppress DC.

M ₂ =ρ ₀ Δp ₀ +(ρ ₁ Δp ₁ cosα)/2

Macroscopically, the cumulative effect of thermodynamic and mechanical asymmetry in the refrigerator system, especially in the regenerator, is reflected in the average pressure difference between the compressor back pressure chamber and the gas storage and the phase difference between the pressure waves. It can be seen from the above formula that the phase difference between the 0th-order quantity (average pressure) and 1st-order quantity of pressure and the density and pressure difference is the main reason for the formation of direct current. Therefore, the above-mentioned specific implementation method can effectively adjust the average pressure difference between the back pressure chamber of the pressure wave generator and the gas storage and the phase difference between the pressure waves, thereby suppressing the formation of direct current.

Experiments were carried out using a pulse tube refrigerator that suppresses direct current as shown in Figure 1. A linear compressor was used to drive a coaxial pulse tube refrigerator without bidirectional air intake. The inner diameter of the pulse tube was 6.7mm, and the inner diameter of the cold storage was 11.7mm. The valve directly connected to the back pressure chamber of the pressure wave generator of the pulse tube refrigerator and the gas storage to adjust the gas flow is a flow valve. Part of the experimental results are shown in Figure 2a and Figure 2b. By adjusting the opening of the small orifice valve and the opening of the flow valve, the average pressure difference and phase difference between the back pressure chamber of the compressor and the gas storage will change greatly. After adopting the above-mentioned embodiment, the minimum refrigeration temperature of the pulse tube refrigerator is significantly lowered.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made, these improvements and modifications It should also be regarded as the protection scope of the present invention.

Claims (11)

1. pulse tube refrigerating machine that suppresses direct current; It is characterized in that; Comprise pressure wave generator (A) and pulse tube refrigerating machine (B), said pulse tube refrigerating machine (B) comprises regenerator (1), pulse tube (2), phase-modulation element (3) and air reservoir (4), and said pulse tube (2) is positioned at said regenerator (1); One end of regenerator (1) links to each other with said pressure wave generator (A) through first tube connector (6); The other end of regenerator (1) links to each other with pulse tube cool end heat exchanger (5), and pulse tube hot end heat exchanger (7) links to each other with said phase-modulation element (3), air reservoir (4) successively, directly is communicated with by governor motion between the back pressure cavity of said pressure wave generator (A) and the air reservoir (4).

2. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 1 is characterized in that, said pressure wave generator (A) is Linearkompressor or is the crank type compressor.

3. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 1 is characterized in that, said pulse tube refrigerating machine (B) is the single-stage pulse tube refrigerating machine of U type, coaxial or straight line.

4. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 1 is characterized in that, said pulse tube refrigerating machine (B) is the multi-stage pulse tube refrigeration machine of U type, coaxial or straight line.

5. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 1 is characterized in that, phase-modulation element (3) is choke valve, inertia tube or bidirection air intake valve, perhaps above-mentioned three's combination in any.

6. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 1 is characterized in that, said governor motion is the valve and/or second tube connector of adjustable gas flow and phase place.

7. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 6 is characterized in that, said valve is asymmetric nozzle, check valve, flow valve or its combination.

8. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 6 is characterized in that, the diameter range of said second tube connector is 0.5 millimeter to 5 centimetres.

9. the pulse tube refrigerating machine of inhibition direct current as claimed in claim 8 is characterized in that, said second tube connector is the equal diameter pipe; Perhaps said second tube connector comprises the pipe of some kinds of different-diameters that link together; Perhaps said second tube connector is a diameter continually varying reducer pipe.

10. like the pulse tube refrigerating machine of each described inhibition direct current of claim 1-9, it is characterized in that the frequency of said pulse tube refrigerating machine (B) is 5Hz to 300Hz.

11. the pulse tube refrigerating machine like each described inhibition direct current of claim 1-9 is characterized in that, the cryogenic temperature scope of said pulse tube refrigerating machine (B) is 273K to 1K.

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