CN100572987C - A kind of thermoacoustic driving pulse pipe refrigerating machine - Google Patents

Abstract

The present invention relates to a kind of thermoacoustic driving pulse pipe refrigerating machine, comprise a thermoacoustic engine and a pulse tube refrigerating machine, and connect the connection pipe of the two, the length of described connection pipe is that 1/10 to 1/4 sound wave is long.This cross-sectional area that connects pipe is than long-pending little with the engine flow channel cross-section of thermoacoustic engine joint; Its shape can be the equal diameter pipe, have long tube that the pipe of 2 to 4 kinds of different-diameters is formed by connecting or near thermoacoustic engine to pulse tube refrigerating machine place diameter continually varying pipe.Compared with prior art, thermoacoustic driving pulse pipe refrigerating machine provided by the invention has inserted a long tube between the pulse tube refrigerating machine of thermoacoustic engine and its driving, when having kept thermoacoustic driving pulse pipe refrigerating machine not have the characteristics of any moving component, make in-engine pressure wave become big through fluctuation amplitude behind this long tube, be that thermoacoustic driving pulse pipe refrigerating machine provided by the invention has than high pressure ratio, thereby its refrigeration performance is improved.

Description

A kind of thermoacoustic driving pulse pipe refrigerating machine

Technical field

The invention belongs to refrigeration and cryogenic technique field, specifically relate to a kind of thermoacoustic driving pulse pipe refrigerating machine.

Background technology

Pulse tube refrigerating machine is because the moving component under the no low temperature becomes the focus and emphasis in the small-sized Cryo Refrigerator research field over past ten years.Usually, pulse tube refrigerating machine needs the mechanical oilless (oil free) compressor under the room temperature that pressure wave is provided, and this compressor arrangement complexity, the cost height, and restricted the pulse tube refrigerating machine long term reliability.

Thermoacoustic engine be a kind of novel be the device of acoustic energy with thermal power transfer, can need not any moving component and pressure wave is provided.It comes down to a kind of compressor that utilizes heat energy, and is simple in structure and reliability is very high.Along with people's close attention and further investigation, the actual performance of thermoacoustic engine is largely increased in nearly ten years, and the hot merit conversion efficiency of thermoacoustic engine has reached 30% at present.

The thermoacoustic driving pulse pipe refrigerating machine that the coupling of thermoacoustic engine and pulse tube refrigerating machine is obtained in the past is the direct-connected mode of connecting pipe of having only several centimetre lengths that adopts between the two.This thermoacoustic driving pulse pipe refrigerating machine can form the Cryo Refrigerator of complete movement-less part, has incomparable advantage aspect cost and the reliability.The obtainable minimum temperature of this coupled system is 68.8K at present, has broken through liquid nitrogen temperature.Limit this coupled system and obtain more that the bottleneck of low temperature is the pressure ratio lower (pressure ratio is defined as the maximum of surge pressure divided by minimum of a value) that common thermoacoustic engine can provide.Adopt helium working medium generally can only obtain pressure ratio about 1.2, even and if this pressure ratio also be not easy to realize.

In order to obtain lower cryogenic temperature and bigger refrigerating capacity, high pressure ratio is one of emphasis of research at present promptly to need the sound-driving pulse tube refrigerating machine of feasible heat to obtain more.

Summary of the invention

The pressure ratio of thermoacoustic driving pulse pipe refrigerating machine that the objective of the invention is to overcome prior art is lower, thereby by increasing the length of connecting pipe, provides a kind of thermoacoustic driving pulse pipe refrigerating machine that has than high pressure ratio, higher refrigeration performance.

The objective of the invention is to realize by the following technical solutions:

Thermoacoustic driving pulse pipe refrigerating machine provided by the invention, comprise a thermoacoustic engine and a pulse tube refrigerating machine, between described thermoacoustic engine and pulse tube refrigerating machine, connect pipe, the length of described connection pipe is between 1/10 sound wave length is long to 1/4 sound wave, in this scope, can select different optimum lengths according to refrigeration machine impedance operator difference.

For example: with the helium is working medium to the optimum length of described connection pipe and different according to Working medium gas, operating temperature and operating frequency different, 69 hertz of operating frequencies, and temperature 300K, the optimum length that then connects pipe is between 1.5～7.4 meters.

The cross-sectional area of described connection pipe is less than long-pending with the engine flow channel cross-section of thermoacoustic engine joint, and its diameter is 1 millimeter～5 centimetres.

Described connection pipe is selected from following three kinds of shapes:

(1) equal diameter pipe;

(2) long tube that is formed by connecting by the pipe of 2 to 4 kinds of different-diameters;

(3) near thermoacoustic engine to pulse tube refrigerating machine place diameter continually varying reducer pipe.

Described thermoacoustic engine is traveling wave thermoacoustic engine or standing wave thermoacoustic engine.

Described pulse tube refrigerating machine is the single-stage pulse tube refrigerating machine of straight line, U type layout or coaxial arrangement, perhaps is the multi-stage pulse tube refrigeration machine of straight line, U type layout or coaxial arrangement.

One end of described connection pipe can be connected in any position on the thermoacoustic engine, and typical position is: for the standing wave thermoacoustic engine, generally be the joint that is connected in the resonatron and the water cooler of thermoacoustic engine; For traveling wave thermoacoustic engine, generally be the joint of main water cooler with the feedback pipe of thermoacoustic engine.

When prior art is used thermoacoustic engine driving pulse pipe refrigeration machine, it is conventionally believed that connecting pipe is short more good more, generally have only several centimetres, in the hope of reducing flow losses.By comparison, thermoacoustic driving pulse pipe refrigerating machine provided by the invention, key is to have inserted a long tube between the pulse tube refrigerating machine of thermoacoustic engine and its driving, when having kept thermoacoustic engine driving pulse pipe refrigeration machine not have the characteristics of any moving component, make in-engine pressure wave become big through fluctuation amplitude behind this long tube, be that thermoacoustic driving pulse pipe refrigerating machine provided by the invention has than high pressure ratio, thereby its refrigeration performance is improved.

For further specify that the present invention proposes in the principle that is connected long tube lifting pressure ratio between thermoacoustic engine and the pulse tube refrigerating machine, simultaneously also further specify required some principles of following when choosing tube length, will make an explanation to its supercharging principle theoretically below.

When sound wave transmitted in can the harmony wavelength comparable pipeline of a length, it had typical distribution formula parameter characteristic.Give certain pressure wave as openend a at end opening one by one, pipeline end sealing, long 1/4 wavelength, because the other end b of pipeline sealing, will form standing-wave sound field in the time of in the pipeline, the amplitude of pressure wave changes along pipe range, can occur the maximum of amplitude on the sealing interface.The distribution of pressure wave amplitude when the blind end at pipeline is connected to the acoustics load, equally also can occur, adopt linear heat sound theory to analyze here.Linear heat sound theory is the common tool that is used for analyzing little amplitude sound field in the thermoacoustics, and formula (1) and formula (2) are its two equations that are used for describing sound field.

$\frac{d\hat{U}}{\mathrm{dx}}+R_1\hat{p}=0,{\mathrm{<figure-callout\; id="1"\; label="R"\; filenames="C2005100643400008H1.png,C2005100643400008H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_1=\frac{\mathrm{i\&omega;A}[1+(\mathrm{\&gamma;}-1)f_k]}{\mathrm{\&gamma;}{P}_0}---\left(1\right)$

$\frac{d\hat{p}}{\mathrm{dx}}+R_2\hat{U}=0,{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="C2005100643400008H1.png,C2005100643400008H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_2=\frac{\mathrm{i\&omega;\&rho;}}{A(1-f_{\mathrm{\&mu;}})}---\left(2\right)$

ω wherein, A, γ, P ₀, ρ is that angular frequency, flow channel cross-section are long-pending respectively, specific heat ratio, average pressure and gas density.f _μ, f _kBe and relevant functions such as runner geometric parameter, gas rerum natura, operating frequency.

The surge pressure at openend a place

With fluctuation volume flow amplitude

The surge pressure amplitude at blind end b place

With fluctuation volume flow amplitude

So (1) (2) formula is found the solution and can be obtained following relational expression:

$\left[\begin{array}{c}{\hat{p}}_b\\ {\hat{U}}_b\end{array}\right]=\left[\begin{array}{cc}{A}_{11}& A_{12}\\ A_{21}& A_{22}\end{array}\right]\left[\begin{array}{c}{\hat{p}}_a\\ {\hat{U}}_a\end{array}\right]---\left(3\right)$

${\mathrm{<figure-callout\; id="11"\; label="A"\; filenames="C2005100643400009H1.png"\; state="\{\{state\}\}">A</figure-callout>}}_{11}=A_{22}\cosh \left(\sqrt{R_1{R}_{2}L}\right)$

$A_{12}=-\sqrt{\frac{R_2}{R_1}}\sinh \left(\sqrt{R_1{R}_{2}L}\right),---\left(4\right)$

$A_{21}=-\sqrt{\frac{R_1}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="C2005100643400008H1.png,C2005100643400008H2.png"\; state="\{\{state\}\}">R</figure-callout>}}_2}}\sinh \left(\sqrt{R_1{R}_{2}L}\right)$

Openend a is the input of pressure wave, and blind end b is connected to the pulse tube refrigerating machine load.If the surge pressure at a place

Known, the impedance of pulse tube refrigerating machine $Z={\hat{P}}_b/{\hat{U}}_b$ Known, pressure oscillation magnification ratio r is defined as so

$r=\frac{\left|{\hat{P}}_b\right|}{\left|{\hat{P}}_a\right|}=\left|\frac{1}{-A_{12}+A_{22}Z}Z\right|---\left(5\right)$

Typically, select 10mm internal diameter copper tube for use, as Z=(3.9-3.4i) * 10 ⁸The time, adopt helium working medium, average pressure 2.0Mpa, temperature 300K, in the pressure oscillation of openend input 0.1MPa, 90Hz, Fig. 1 shows the situation of change of impedance inlet pressure fluctuation amplitude with different pipe ranges, can see the pressure oscillation amplification effect significantly, especially when pipe range was 2.65 meters, the pressure oscillation amplitude of load end can be increased to about 10 times

Description of drawings

Fig. 1 is the situation of change of impedance inlet pressure fluctuation amplitude with different pipe ranges;

Fig. 2 is the schematic diagram that the traveling wave thermoacoustic engine of embodiment 1 drives single-stage linear pattern pulse tube refrigerating machine;

Fig. 3 is the schematic diagram that the standing wave thermoacoustic engine of embodiment 2 drives U type two-stage pulse tube refrigerating machine;

Wherein: the A thermoacoustic engine, B connects long tube, C pulse tube refrigerating machine, 1 main water cooler, 2 regenerators, 3 heaters, 4 thermal buffer tubes, 5 secondary water coolers, 6 feedback pipes, 7 taper resonatrons; 8 hot chambeies, 9 heaters, 10 plates are folded, 11 water coolers, the resonator that 12 equal diameter pipes and cavity are formed, 13 water coolers, 14 regenerators, 15 cold heads, 16 pulse tubes, 17 little ports valves, 18 air reservoirs, 19 two-way valves, 20 secondary regenerators, 21 one-level air reservoirs, 22 one-level inertance tubes, 23 one-level pulse tubes, 24 secondary air reservoirs, 25 secondary inertance tubes, 26 secondary vein washing pipes, 27 water coolers, 28 one-level regenerators.

The specific embodiment

Describe the thermoacoustic driving pulse pipe refrigerating machine that has than high pressure ratio, higher refrigeration performance provided by the invention in detail below in conjunction with Fig. 2 and Fig. 3.

Embodiment 1,

Adopt constructional device as shown in Figure 2, use traveling wave thermoacoustic engine to drive single-stage linear pattern pulse tube refrigerating machine, wherein A is a traveling wave thermoacoustic engine, mainly comprises main water cooler 1, regenerator 2, heater 3, thermal buffer tube 4, secondary water cooler 5, feedback pipe 6, taper resonatron 7; C is a single-stage linear pattern pulse tube refrigerating machine, mainly comprises water cooler 13, regenerator 14, cold head 15, pulse tube 16, aperture valve 17, air reservoir 18, two-way valve 19; The two connects by connecting long tube B, and described connection pipe is connected in the joint of main water cooler with the feedback pipe of traveling wave thermoacoustic engine.

The diameter of the feedback pipe of this traveling wave thermoacoustic engine is 80mm, and backfeed loop is about 2m, taper resonatron length 4.5m.Adopt helium as working medium, average pressure 2.46MPa, operating frequency is 69Hz (the long 14.8m of being of the corresponding sound wave of this frequency), and single-stage linear pattern pulse tube refrigerating machine regenerator is of a size of the 15mm internal diameter, and length 48mm fills 400 order stainless steel cloths; Pulse tube is of a size of 6mm internal diameter, length 77mm.The isodiametric red copper pipe that adopts 8mm is as connecting long tube, and its length is 2.8m.Experimental result shows, from the amplitude of thermoacoustic engine be the pressure oscillation of 0.128MPa (being that pressure ratio is 1.11) to be amplified to amplitude be that the pressure oscillation of 0.34MPa (being that pressure ratio is 1.32) enters pulse tube refrigerating machine, drive this refrigeration machine and obtain the 65.7K lowest temperature.

Embodiment 2,

Adopt constructional device as shown in Figure 3, use the standing wave thermoacoustic engine to drive U type two-stage pulse tube refrigerating machine, wherein A is the standing wave thermoacoustic engine, mainly comprises hot chamber 8, heater 9, and plate folds 10, water cooler 11, the resonator 12 that equal diameter pipe and cavity are formed; C is a U type two-stage pulse tube refrigerating machine, mainly comprises secondary regenerator 20, one-level air reservoir 21, one-level inertance tube 22, one-level pulse tube 23, secondary air reservoir 24, secondary inertance tube 25, secondary vein washing pipe 26, water cooler 27, one-level regenerator 28; The two connects by connecting long tube B, and described connection pipe is connected in the joint of the resonatron and the water cooler of standing wave thermoacoustic engine.

The heater of this standing wave thermoacoustic engine, plate superimposition water cooler internal diameter are 80mm, and the resonatron internal diameter is 50mm, and length 3.3m adopts helium as working medium, average pressure 3.0MPa, and operating frequency is 88Hz (the long 11.6m of being of the corresponding sound wave of this frequency).The one-level regenerator is of a size of the 25mm internal diameter in the two-stage pulse tube refrigerating machine, and length 55mm fills 400 order stainless steel cloths; The one-level pulse tube is of a size of 10mm internal diameter, length 100mm; The secondary regenerator is of a size of the 10mm internal diameter, and length 35mm fills 500 order stainless steel cloths; The secondary vein washing pipe is of a size of 6mm internal diameter, length 70mm.The isodiametric red copper pipe that adopts internal diameter 8mm is as connecting long tube, its length is 2.6m, be that the pressure oscillation of 0.073MPa (being that pressure ratio is 1.05) is amplified to the pressure oscillation that amplitude is 0.19MPa (being that pressure ratio is 1.14) and enters the two-stage pulse tube refrigerating machine from the amplitude of standing wave thermoacoustic engine in the experiment, drive this refrigeration machine and obtain the 60K lowest temperature.

Claims (7)

1, a kind of thermoacoustic driving pulse pipe refrigerating machine, comprise a thermoacoustic engine and a pulse tube refrigerating machine, connect pipe between described thermoacoustic engine and pulse tube refrigerating machine, it is characterized in that: the length of described connection pipe is between 1/10 sound wave length is long to 1/4 sound wave.

2, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1 is characterized in that: when Working medium gas is a helium, operating frequency is 69 hertz, and when operating temperature was 300K, the length of described connection pipe was 1.5～7.4 meters.

3, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1 is characterized in that: the cross-sectional area of described connection pipe is than long-pending little with the engine flow channel cross-section of thermoacoustic engine joint.

4, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1 is characterized in that: the diameter of described connection pipe is 1 millimeter～5 centimetres.

5, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1 is characterized in that: described connection pipe is selected from following three kinds of shapes:

(1) equal diameter pipe;

(2) long tube that has the pipe of 2 to 4 kinds of different-diameters to be formed by connecting;

(3) near thermoacoustic engine to pulse tube refrigerating machine place diameter continually varying reducer pipe.

6, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1 is characterized in that: described thermoacoustic engine is traveling wave thermoacoustic engine or standing wave thermoacoustic engine.

7, thermoacoustic driving pulse pipe refrigerating machine as claimed in claim 1, it is characterized in that: described pulse tube refrigerating machine is that straight line, U type are arranged or coaxial arrangement single-stage pulse tube refrigerating machine, perhaps is that straight line, U type are arranged or coaxial arrangement multi-stage pulse tube refrigeration machine.

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