CN101210749A - A tandem thermoacoustic system - Google Patents

Abstract

The present invention provides a tandem thermoacoustic system, which includes at least two stages of thermoacoustic devices connected in series; the first stage thermoacoustic device includes: one or at least two λ/2 acoustic resonators connected in parallel λ is the wavelength of the sound wave; and a standing wave thermoacoustic engine installed in the standing wave region in the resonant tube of each λ/2 acoustic resonator; A wave type thermoacoustic engine, the temperature gradient of the traveling wave type thermoacoustic engine is the same as that of the standing wave type thermoacoustic engine; the last stage thermoacoustic device includes: one or at least two parallel λ/ 2 acoustic resonators; λ is the wavelength of the sound wave; and a traveling-wave thermoacoustic refrigerator or an acoustic-electric transducer installed in the traveling-wave region of each lambda/2 acoustic resonator resonance tube, the traveling-wave thermoacoustic refrigerator The temperature gradient is opposite to that of the standing wave type thermoacoustic engine of the first stage thermoacoustic device.

Description

A tandem thermoacoustic system

field of invention

The invention mainly relates to a thermoacoustic system, in particular to a tandem thermoacoustic system in which a thermoacoustic engine drives a thermoacoustic refrigerator or thermoacoustic power generation and other energy conversion mechanisms.

Background technique

Thermoacoustic heat engines (including thermoacoustic engines, thermoacoustic refrigerators and thermoacoustic heat pumps) fundamentally eliminate moving parts, use environmentally friendly natural working fluids, and can effectively use low-grade heat energy, so they are widely used in space technology, natural gas liquefaction and Environmental protection and refrigeration engineering have shown important application prospects. However, the improvement of thermoacoustic conversion efficiency has always been the core technical issue restricting the engineering and commercialization of thermoacoustic heat engines. Compound. Standing-wave thermoacoustic heat engines rely on the irreversible thermoacoustic conversion process, so their efficiency is limited. The energy efficiency ratio (COP) of a standing wave thermoacoustic refrigerator in the temperature range of a household refrigerator is only 0.6; the thermal efficiency of a standing wave thermoacoustic engine usually does not exceed 20%. Due to the low acoustic impedance of the loop, the simple annular ring traveling wave thermoacoustic heat engine causes serious viscous loss and shuttling heat loss, and the actual efficiency is also very low. Although the thermal efficiency of the traveling standing wave composite thermoacoustic Stirling engine can reach 30%, due to the Gedeon acoustic direct current loss in the loop, additional measures to effectively suppress the acoustic flow are required. In U.S. Patent No. 6,658,862 (G.W.Swift. Cascaded thermoacoustic devices. U.S. Patent No. 6,658,862, 2003.), a traveling standing wave cascaded thermoacoustic heat engine is described, and its structure is limited to a single half-wavelength The standing wave thermoacoustic engine and traveling wave thermoacoustic engine are arranged in the acoustic resonator, but the high impedance traveling wave region is usually too narrow, and the number of cascade series is extremely limited. No more than two grades.

Contents of the invention

The purpose of the present invention is to overcome the defects of the above-mentioned prior art, thereby providing a tandem thermoacoustic system that can avoid the loss of acoustic circulation and realize efficient thermoacoustic conversion, which is beneficial to the integration of the thermoacoustic system.

The tandem thermoacoustic system provided by the present invention includes at least two stages of thermoacoustic devices connected in series;

The first stage thermoacoustic device comprises:

one or at least two λ/2 acoustic resonators connected in parallel; λ is the acoustic wavelength; and

A standing wave thermoacoustic engine installed in the standing wave region of each λ/2 acoustic resonator resonant tube; a traveling wave thermoacoustic engine installed in the high impedance traveling wave region of each λ/2 acoustic resonator resonant tube, so The temperature gradient of the traveling wave thermoacoustic engine is the same as that of the standing wave thermoacoustic engine;

The last stage thermoacoustic device includes:

one or at least two λ/2 acoustic resonators connected in parallel; λ is the acoustic wavelength; and

A traveling-wave thermoacoustic refrigerator or an acoustic-electric transducer installed in the traveling-wave region of each λ/2 acoustic resonator resonant tube, the temperature gradient of the traveling-wave thermoacoustic refrigerator and the first-stage thermoacoustic The temperature gradient of the standing wave type thermoacoustic engine of the device is opposite.

The tandem thermoacoustic system provided by the present invention may further include an intermediate thermoacoustic device located between the first-stage thermoacoustic device and the last-stage thermoacoustic device and connected in series;

The intermediate stage thermoacoustic device includes:

one or at least two λ/2 acoustic resonators connected in parallel; λ is the acoustic wavelength; and

A traveling-wave thermoacoustic engine installed in the high-impedance traveling-wave region of each λ/2 acoustic resonator resonance tube, the temperature gradient of the traveling-wave thermoacoustic engine and the standing wave thermoacoustic of the first-stage thermoacoustic device The temperature gradient of the engine is the same.

The resonance tube of the λ/2 acoustic resonator is provided with a hollow annular tube communicating with it; the plane where the hollow annular tube is located is perpendicular to the resonance tube of the λ/2 acoustic resonator; the hollow The distance between the intersection point where the annular tube communicates with the resonance tube of the λ/2 acoustic resonator and the sweet spot of the λ/2 acoustic resonator is less than or equal to 1/8λ, and satisfies the formula p _J /U _J =ρa/Acot(2πL/λ), where p _J is the sound pressure at the intersection of the hollow annular tube and the resonant tube of the λ/2 acoustic resonator, and U _J is the acoustic pressure of the λ/2 acoustic resonator The volume flow velocity of the working medium at the connecting intersection point in the resonance tube of the resonator, ρ is the average density of the working medium in the resonance tube of the λ/2 acoustic resonator, and a is the working medium in the resonance tube of the λ/2 acoustic resonator The speed of sound, A is the cross-sectional area of the hollow annular tube, L is the length of the hollow annular tube; the sweet spot refers to the point where the phase difference between the sound pressure and the oscillation velocity in the resonant tube is zero.

The shape of the hollow annular tube is a circular, oval or rectangular closed loop annular tube.

The ratio of the diameter of the resonance tube of the λ/2 acoustic resonator to the hollow annular tube is 2-4, and the ratio of the length of the hollow annular tube to the diameter of the hollow annular tube is 8-20;

The starting end of the resonance tube of the λ/2 acoustic resonator of the first-stage thermoacoustic device or the end of the resonance tube of the λ/2 acoustic resonator of the last-stage thermoacoustic device is open, or a resonant cavity or Move the piston.

The two ends of the resonant tube of the λ/2 acoustic resonator of the intermediate thermoacoustic device are respectively connected with a resonant cavity, that is, has a dumbbell structure.

The resonant cavity is a hollow spherical or cylindrical resonant cavity.

Those skilled in the industry know that a traveling wave thermoacoustic engine generally consists of a cooler, a heater, and a regenerator arranged between the cooler and the heater. A traveling-wave thermoacoustic refrigerator generally consists of a low temperature heat exchanger, a room temperature heat exchanger, and a regenerator between the two heat exchangers.

In the present invention, the distance between the center of the regenerator in the traveling wave thermoacoustic engine and the sweet spot of the λ/2 acoustic resonator of the traveling wave thermoacoustic engine is less than or equal to 1/8λ .

In the present invention, the distance between the center of the regenerator in the traveling wave thermoacoustic refrigerator and the best listening point of the λ/2 acoustic resonator of the traveling wave thermoacoustic refrigerator is less than or equal to 1 /8λ.

The regenerators of the traveling-wave thermoacoustic engine and the traveling-wave thermoacoustic refrigerator are multi-channel structures, and the hydraulic radius of each channel is 0.1-0.5 times that of the oscillating heat-permeable layer of the medium.

The standing wave thermoacoustic engine includes a cooler, a heater, and a thermoacoustic pile located between the cooler and the heater. The center of the thermoacoustic pile is between the sweet spot of the λ/2 acoustic resonator. The distance between them is 0.025λ-0.3λ.

The thermoacoustic stack is composed of a laminated structure or wire mesh, and the hydraulic radius of the micropores is 1-2 times that of the heat permeable layer.

The working medium of the λ/2 acoustic resonator is nitrogen, helium, carbon dioxide, argon, hydrogen or a mixture of two or more of the above gases.

The resonant tube cross-section of the λ/2 acoustic resonator is circular or square; the tube wall is made of dense and rigid material, and the inner surface of the tube wall is smooth and has no fine gaps; the length of the resonant tube and the inner diameter of the circular section Or the ratio of the side lengths of the square section is in the range of 10 to 50, and the length of the resonance tube is in the range of 1 to 1.25 times the half wavelength.

In the tandem thermoacoustic system, the sound work is initially generated by the thermoacoustic engine working in the standing wave mechanism, and then propagated through the traveling wave thermoacoustic engines of various stages and amplified step by step until the last stage of traveling wave thermoacoustic Consumed by energy conversion units such as refrigerators or acoustic-electric transducers.

The structure of the tandem thermoacoustic system belongs to a linear arrangement, which avoids the appearance of Gedeon acoustic direct current, thereby making full use of multiple high-impedance near-traveling wave phase regions, and more acoustic power in the subsequent tandem The heat energy and sound energy are converted in a form close to the Stirling cycle in the regenerator, so it has the highest thermoacoustic conversion efficiency that can be theoretically achieved.

The high-impedance traveling-wave region refers to the region within the range of plus or minus 45 degrees of the phase difference between the sound pressure and the oscillation velocity in the resonant tube.

The traveling-wave thermoacoustic machines of the various levels have the meaning of cooperating front and back, because there is only one sweet spot in a half-wavelength acoustic resonator, and the traveling wave region near the sweet spot usually only occupies the wavelength 2.5%, in order to meet the thermal insulation between the thermoacoustic engine stage and the refrigeration stage, a thermal buffer distance of about 1% of the wavelength is required, so the tandem thermoacoustic system is at least a full-wavelength resonant system. In theory, this thermoacoustic system Can be serialized indefinitely;

The loop structure of the extended high-impedance area, as shown in Figure 7a, is vertically arranged between the loop and the resonance tube of the λ/2 acoustic resonator, such a structure will not cause acoustic circulation in the resonance tube, and the hollow annular tube The distance between the connecting intersection connected with the resonant tube of the λ/2 acoustic resonator and the sweet spot of the λ/2 acoustic resonator is less than or equal to 1/8λ, and the transverse width of the hollow annular tube is required The cross-sectional area A and the length L of the hollow annular tube must meet the following acoustic impedance relationship (for specific reasons, please refer to the explanation in the working principle section below):

p _J /U _J ＝ρa/Acot(2πL/λ) (1)

In the formula, p _J is the sound pressure at the intersection of the hollow annular tube and the resonance tube of the λ/2 acoustic resonator, and U _J is the volume of the working medium at the intersection of the resonance tube of the λ/2 acoustic resonator flow velocity;

The present invention is based on the understanding of the sound field characteristics of the actual closed space and its modulation mechanism, combined with the law of component acoustic impedance conditional coupling, from the perspective of fluctuations, to create an acoustic region that is conducive to high-efficiency thermoacoustic conversion, and through multi-stage series connection, The sound power is amplified layer by layer during the transmission process, so as to achieve greater sound power output at a high efficiency level.

Compared with the prior art, the key of the tandem thermoacoustic system provided by the present invention is to use the law of sound wave propagation to modulate the high-impedance traveling wave phase region, and to ensure the realization of the expected sound field from the design of the acoustic structure. The loop structure of partially extending the high-impedance region is more compact, simple and flexible than the LC method.

In order to further illustrate the rationality of the structural design of the present invention, and also further illustrate the principles to be followed when carrying out the structural design, the following will be explained from the working principle.

Usually, the thermoacoustic self-excited oscillation starts at the fundamental frequency (the energy loss of the system is the smallest at this time). In order to realize the sound field conditions of the tandem thermoacoustic system under the fundamental frequency vibration, a full-wavelength acoustic resonator such as that shown in Figure 1 is used as the For example, it consists of two slender acoustic resonance tubes and three resonant cavities. The resonators at the two ends can also be opened or moved. The middle resonant cavity can ensure that the system is excited at the fundamental frequency. According to the interference theory of sound wave propagation, the sound field characteristics of this resonator are as follows:

p ₁ =[p _sa cosk′x-ip _ta sink′x]e ^iωt

${\mathrm{<span\; class="notranslate">\; u</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}{\mathrm{<span\; class="notranslate">\; c</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; p</span>}}_{\mathrm{<span\; class="notranslate">\; ta</span>}}\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; ip</span>}}_{\mathrm{<span\; class="notranslate">\; sa</span>}}\mathrm{<span\; class="notranslate">\; sin</span>}{\mathrm{<span\; class="notranslate">\; k</span>}}^{<span\; class="notranslate">\; \&prime;</span>}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; e</span>}}^{\mathrm{<span\; class="notranslate">\; i\&omega;t</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 2</span>}<span\; class="notranslate">\; )</span>$

p _sa =p _ia +p _ra p _ta =p _ia -p _ra

Among them: k′=k-iα k=ω/c ₀ k′ wave vector, the acoustic boundary condition determines the wave vector; α attenuation coefficient.

It can be seen that the actual closed sound field is composed of two components of standing wave and traveling wave, where p _sa and p _ta represent the complex amplitudes of standing wave component and traveling wave component respectively. Figure 2 is the waveform spatial distribution of the fundamental frequency oscillation in a full-wavelength tandem acoustic resonator claimed in this patent. It can be seen from the figure that there are two local high-impedance regions near the sweet spot, and The phase difference between the fluctuating sound pressure vector and the fluctuating velocity vector in this area is close to traveling waves, which is suitable for the arrangement of a regenerator unit with high-efficiency thermoacoustic conversion. High conversion efficiency.

Due to the short wavelength of the high-frequency thermoacoustic system, the size of the entire thermoacoustic device can be reduced, but often the local high-impedance area is also shortened accordingly, and there is not enough space to arrange the thermoacoustic element section. The present invention proposes a method in which a hollow annular tube connected to the high impedance of the existing λ/2 acoustic resonator resonant tube is provided as an acoustic circuit, and the acoustic impedance of the hollow annular tube is reasonably designed to extend the The purpose of the λ/2 acoustic resonator resonator tube high impedance region, as shown in Fig. 7a. The sound pressure at the intersection of the hollow annular tube and the resonance tube of the λ/2 acoustic resonator is denoted as p _J , and the volume flow velocity of the working medium at the intersection of the resonance tube of the λ/2 acoustic resonator is denoted as U _J , assuming that the volume flow velocity of the working medium in the resonance tube of the λ/2 acoustic resonator originally mentioned is -U _J , how to bypass a reasonable acoustic structure so that it becomes +U _J after passing through the bypass port, so high impedance The zone will be effectively extended. At present, the method of using LC (acoustic sense-acoustic capacity) acoustic structure, but usually the proportion of LC is relatively large, which not only affects the compactness of the system but also increases the difficulty of starting the vibration of the entire thermoacoustic system. For this reason, this patent proposes a new loop bypass regulation structure. Through the analysis of the sound field in the hollow annular tube, as shown in Figure 7b, the entire hollow annular tube is actually equivalent to an acoustic resonant tube with openings at both ends, and the two ends always have velocity fluctuations in opposite directions. The velocity of the flow is +U _J , spread out along the circumference of the loop, and the other branch must be -U _J , but since this branch is also connected to the main road, it is still +U _J for the main road. Then the volume flow velocity of the main road becomes +U _J after the fork. This necessarily requires the loop to meet a certain acoustic impedance condition, which is shown in formula (1).

The advantage of the present invention described above is:

1. The structure is simple, easy to integrate, and can achieve higher output power (or cooling effect) at a high efficiency level;

2. The loop bypass measure for extending the high impedance area is simple and feasible. The innovation point of the present invention is to break through the traditional thermoacoustic system design idea, skillfully utilize the law of sound wave propagation, and through the analysis of the sound field distribution law and impedance matching characteristics, ensure the modulation of the local high-impedance traveling wave sound field with a more compact and novel acoustic structure ( including extensions). This is a traveling-wave thermoacoustic heat engine that avoids Giton-acoustic DC loss, which is completely different from the annular ring traveling-wave machine structure of current thermoacoustic technology.

Description of drawings

Figure 1 shows four full-wavelength linear tandem thermoacoustic resonators;

Fig. 2 is the waveform spatial distribution of the fundamental frequency oscillation of a full-wavelength tandem acoustic resonator filled with 3MPa nitrogen;

Fig. 3 is a schematic diagram of a full-wavelength linear tandem thermoacoustic engine driving a thermoacoustic refrigerator;

Fig. 4 is a schematic diagram of a device for driving a thermoacoustic refrigerator driven by a full-wavelength U-shaped thermoacoustic engine;

Fig. 5 is a schematic diagram of a series-parallel hybrid integrated serial heat-driven thermoacoustic refrigeration device;

Fig. 6 is a schematic diagram of a series (ring) integrated dual-wavelength tandem heat-driven thermoacoustic refrigeration device;

Figure 7a is a hollow annular tube that effectively extends the high impedance region;

Fig. 7b is an analysis diagram of the sound field of the hollow annular tube extending the high impedance region.

Detailed ways

Below in conjunction with accompanying drawing, the present invention is further explained and illustrated:

Example 1

This embodiment is a tandem thermoacoustic refrigeration system in which a two-stage cascaded thermoacoustic engine drives a traveling wave thermoacoustic refrigerator. Its structure is shown in Figure 3, two λ/2 acoustic resonators They are connected in series, the arc in the figure is the sound pressure (P ₁ ) distribution along the course, and the following components are arranged in series along the direction of sound power propagation: the first resonant cavity 1, the first resonant tube 2, the first water-cooled 3, the first thermoacoustic pile 4, the first heater 5, the first thermal buffer tube 6, the second water cooler 7, the first regenerator 8, the second heater 9, the second thermal buffer tube 10, the first A secondary water cooler 11, a second resonant cavity 13, a second resonant tube 14, a third water cooler 15, a second regenerator 16, a cold head 17, a third thermal buffer pipe 18, a second secondary water cooler 19, the first Three resonant cavities 21.

Among the above components, the distance between the center of the first thermoacoustic pile 4 and the best listening point of the first resonant tube 2 is 0.025λ～0.30λ; The distance is less than or equal to 1/8λ, and the distance between the center of the second regenerator 16 and the best listening point of the second resonance tube 14 is less than or equal to 1/8λ;

The regenerator in this embodiment can adopt a multi-channel structure, and the hydraulic radius of each micro-channel is 0.1-0.5 times that of the medium oscillating heat permeable layer; the thermoacoustic stack can use a plate stack structure or be composed of a wire mesh, wherein , the hydraulic radius of the channel is 1-2 times that of the heat permeable layer.

The device is actually a full-wavelength resonant system, and all components are connected in series in sequence, that is, cascaded thermoacoustic engines and thermoacoustic refrigerators work in a linear series. The working medium can be helium, nitrogen, carbon dioxide, and argon. Or a single working gas such as hydrogen, or a mixture of two or more gases among them. When the temperature gradient between the first heater 5 and the first water cooler 3 exceeds the critical temperature gradient, the acoustic work will be generated in the first thermoacoustic pile 4 and start to propagate to the downstream components in turn, and in the first round Amplified in the heater 8, the magnification is theoretically the ratio of the absolute temperature of the second heater 9 and the first water cooler 7, and finally consumed in the second regenerator 16, thereby obtaining the refrigeration temperature of the cold head 17 and cooling capacity.

The calculation formula of the above critical temperature gradient is $\&dtri;T_{\mathrm{crit}}=\frac{\left|{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="A20061017165400152.png,A20061017165400171.png"\; state="\{\{state\}\}">p</figure-callout>}}_1\right|/{\mathrm{\&rho;}}_m{C}_p}{\left|{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="A20061017165400152.png,A20061017165400171.png"\; state="\{\{state\}\}">u</figure-callout>}}_1\right|/\mathrm{A\&omega;}},$ where p ₁ is the sound pressure amplitude in the thermoacoustic reactor, U ₁ is the volumetric flow velocity of the working medium in the thermoacoustic reactor; A is the flow area of the working medium in the thermoacoustic reactor; Cp is the constant pressure of the working medium in the thermoacoustic reactor Specific heat; ω is the angular frequency of oscillation.

Figure 2 shows the spatial distribution of the fundamental frequency oscillation waveform when the above-mentioned device uses 3MPa nitrogen as the working medium. In the figure, PAN represents the antinode of the sound pressure, and VN represents the node of the velocity. The best listening point can be seen from the figure There are two local high-impedance regions nearby, and the phase difference between the sound pressure and the velocity oscillation in this region is close to that of a traveling wave.

In order to effectively extend the length of the traveling wave region, a hollow annular tube perpendicular to and connected to the resonant tube as shown in Figure 7a can also be used at the first regenerator 8 and the second regenerator 16. The hollow annular tube The distance between the connecting intersection point where the tube communicates with the resonance tube of the λ/2 acoustic resonator and the sweet spot of the λ/2 acoustic resonator is less than or equal to 1/8λ, and satisfies the formula p _J /U _J = ρa/Acot(2πL/λ), where p _J is the sound pressure at the intersection of the hollow annular tube and the resonance tube of the λ/2 acoustic resonator, and U _J is the sound pressure of the λ/2 acoustic resonator The volume flow velocity of the working medium at the connected intersection point in the resonance tube, ρ is the average density of the working medium in the resonance tube of the described λ/2 acoustic resonator, and a is the sound velocity of the working medium in the resonance tube of the described λ/2 acoustic resonator, A is the cross-sectional area of the hollow annular tube, L is the length of the hollow annular tube; the sweet spot refers to the point where the phase difference between the sound pressure and the oscillation velocity in the resonant tube is zero.

The hollow annular tube is circular, elliptical or rectangular, and the ratio of its length to the diameter of the hollow annular tube is 8-20. The ratio of the diameter of the hollow annular tube to the diameter of the resonant tube is 1/ 4-1/2. Numerical simulations show that the acoustic resonant cavity at both ends and in the middle deviates slightly from the sound pressure node. The length of the resonant tube of this device is about 1.2 times the full wavelength, and the thermal efficiency of the engine is more than 25%. The COP of driving the vapor compression refrigeration method is basically the same. This is much higher than the efficiency of the thermoacoustic-driven refrigeration device in the same temperature zone through "long-diameter tube + gas storage" or "small hole + gas storage" phase modulation, because the COP of that structure cannot exceed 1.

The λ/2 acoustic resonator used in this embodiment includes a resonant tube and resonant cavities respectively located at both ends of the resonant tube, wherein the resonant cavities can have different sizes or different shapes, as shown in Figure 1, A in the figure And Figure B is composed of two slender acoustic resonance tubes and three resonant cavities. The resonant cavities can have different sizes, and the resonant cavities can also adopt different shapes. For example, A uses a spherical resonant cavity, which can reduce surface acoustics. Dissipation and cross-section mutation loss, B is to use a relatively thick and short circular tube as a resonant cavity; C is the form of an opening at the end of the boundary resonant tube, D is the form of a moving piston at the end, and the resonant cavity connected between C and D can also be used spherical.

Example 2

This embodiment adopts the tandem thermoacoustic system shown in Figure 4; the system consists of two λ/2 acoustic resonators connected in series to form a U-shaped structure, and the setting, position, working mode and working process of each component in the resonator are all Same as embodiment 1;

The U-shaped tandem method reduces the actual length of the system and can effectively save space. At the same time, since the working medium is mostly nitrogen, helium, carbon dioxide, argon, hydrogen or a mixed gas composed of two or more of the above gases , which is much lower than the acoustic impedance of the stainless steel material of the λ/2 acoustic resonator tube wall, so the acoustic resonant tube at the U-bend part can still be regarded as plane wave propagation, but some local viscous loss will be added.

Example 3

This embodiment adopts the system structure shown in Figure 5; the first-stage thermoacoustic device consists of three λ/2 acoustic resonators with built-in thermoacoustic engines connected in parallel to form a stronger driving device, and then a built-in thermoacoustic cooling device is connected in series The λ/2 acoustic resonator of the machine acts as a second-stage thermoacoustic device. Inside the resonance tube of each λ/2 acoustic resonator in the first-stage thermoacoustic device, there is a standing wave thermoacoustic engine and a traveling wave thermoacoustic engine. In the figure, the first, second and third The standing wave thermoacoustic engines 34, 36, and 38 are composed of two hot and cold end heat exchangers sandwiching a thermoacoustic stack, and the first, second, and third traveling wave thermoacoustic engines 35, 37, 39 and traveling wave type thermoacoustic refrigerator 40 is composed of two hot and cold end heat exchangers sandwiching a regenerator, and the center of the regenerator in each traveling wave thermoacoustic engine is in line with the λ/2 acoustic The distance between the best listening points of the resonators is less than or equal to 1/8λ; the center of the regenerator in the traveling wave thermoacoustic refrigerator is in acoustic resonance with the lambda/2 of the traveling wave thermoacoustic refrigerator The distance between the best listening points of the transducers is less than or equal to 1/8λ, and the temperature gradient of each standing wave thermoacoustic engine is the same, and the temperature gradient of each traveling wave thermoacoustic engine is the same as that of each standing wave thermoacoustic engine The temperature gradient is the same, and the temperature gradient of the traveling wave thermoacoustic refrigerator is opposite to that of each standing wave thermoacoustic engine;

Acoustic work is produced with the thermoacoustic effect of the standing wave mechanism in the first, second, and third standing wave thermoacoustic engines 34, 36, and 38, and then respectively in the first, second, and third traveling wave thermoacoustic The engines 35, 37, 39 are effectively amplified, and then collected in the traveling-wave thermoacoustic refrigerator 40 for consumption. This is an integrated full-wavelength resonant system, which can greatly enhance the compactness of the actual system. One of the biggest shortcomings of the current thermoacoustic device is that it is not compact. The thermoacoustic unit only accounts for a small proportion of the resonant system. The hybrid thermoacoustic The Stirling machine is more obvious.

The three independent λ/2 acoustic resonators connected in parallel in Fig. 5 cannot be replaced by a single λ/2 acoustic resonator with a cross-sectional area three times thicker for two reasons. If the proportion increases, the temperature distribution of the cross-section of the regenerator will be uneven, which will affect the system efficiency; secondly, increasing the diameter of the regenerator will increase the sound volume of the regenerator, causing the phase difference between the local sound pressure and velocity to deviate from the traveling wave phase , in other words, the traveling wave region will be greatly shortened, which is not conducive to the regenerator to fully play the role of amplifying the sound work.

Example 4

In this embodiment, four λ/2 acoustic resonators are connected in series to form a ring shape, as shown in Figure 6, wherein,

A fourth standing wave thermoacoustic engine 42 and a fourth traveling wave thermoacoustic engine 43 are arranged in the resonant tube of the first λ/2 acoustic resonator 41, the fourth standing wave thermoacoustic engine 42 is located in the standing wave region, and its thermal The center of the acoustic pile is 0.025λ to 0.30λ from the sweet spot of the first λ/2 acoustic resonator; the fourth traveling wave thermoacoustic engine 43 is located in the traveling wave region of the first λ/2 acoustic resonator, and its The distance between the center of the heater and the sweet spot of the λ/2 acoustic resonator of the traveling wave type thermoacoustic refrigerator is less than or equal to 1/8λ, and the temperature gradient of the fourth traveling wave type thermoacoustic engine 43 is the same as The temperature gradient of the fourth standing wave thermoacoustic engine 42 is the same;

The traveling wave regions in the second and third λ/2 acoustic resonators 44, 46 are respectively provided with fifth and sixth traveling wave thermoacoustic engines 45, 47, and their positions and temperature gradients are the same as those of the fourth traveling wave thermoacoustic engines. The engine 43 is the same;

The fourth λ/2 acoustic resonator 48 is provided with a traveling-wave thermoacoustic refrigerator 49 ; its position is the same as that of the fourth traveling-wave thermoacoustic engine 43 , and its temperature gradient is the same as that of the fourth traveling-wave thermoacoustic engine 43 .

The sound work is generated in the fourth standing wave thermoacoustic engine 42, and is sequentially amplified step by step in the fourth, fifth, and sixth traveling wave thermoacoustic engines 43, 45, 47, and finally in the traveling wave refrigerator 49. Internal consumption, sound energy is converted into cooling capacity. Simultaneously the traveling wave type thermoacoustic refrigerator 49 of the 4th λ/2 acoustic resonator 48 can be used as cryogenic devices such as the refrigerator, air conditioner, liquefier that obtains cold capacity according to the difference of purposes (from the cold end of the 4th regenerator 9 heat exchanger as the output end), and can also be used as heat pump heating (from the cold and hot end heat exchanger of the fourth regenerator 9 as the output end). This is also a practical and frugal solution, and the proportion of the thermoacoustic core section increases. The device is a 2-wavelength system. After the sound power is generated, it is provided to the energy-consuming unit after three times of exponential growth amplification, which greatly improves the energy utilization efficiency. Theoretically, it can reach a relative Carnot efficiency of 40%.

On the basis of the structure of the above device, the traveling wave thermoacoustic refrigerator 49 can also be replaced by an acoustic-electric transducer, so as to convert the acoustic energy into electrical energy.

Claims (10)

1. tandem type thermoacoustic system, this system comprises the acoustic device of two levels of thermal at least of mutual polyphone;

Described first order thermoacoustic devices comprises:

One or at least two λ parallel with one another/2 acoustic resonator; λ is a wave length of sound; With

Be loaded on a standing wave type thermoacoustic engine in each λ/2 acoustic resonator resonatron standing internal wave districts; Be loaded on the travelling-wave type thermoacoustic engine in high impedance Hang Bo district in each λ/2 acoustic resonator resonatrons, described travelling-wave type thermoacoustic engine thermograde is identical with the thermograde of described standing wave type thermoacoustic engine;

Described afterbody thermoacoustic devices comprises:

One or at least two λ parallel with one another/2 acoustic resonator; λ is a wave length of sound; With

Be loaded on the travelling-wave type hot sound refrigerating machine or the acoustic-electrical transducer in the expert ripple of each λ/2 acoustic resonator resonatrons district, the thermograde of described travelling-wave type hot sound refrigerating machine is opposite with the thermograde of the standing wave type thermoacoustic engine of described first order thermoacoustic devices.

2. by the described tandem type thermoacoustic system of claim 1, it is characterized in that the intergrade thermoacoustic devices that also further comprises between first order thermoacoustic devices and afterbody thermoacoustic devices and contact with it;

Described intergrade thermoacoustic devices comprises:

One or at least two λ parallel with one another/2 acoustic resonator; λ is a wave length of sound; With

Be loaded on the travelling-wave type thermoacoustic engine in each λ/2 acoustic resonator resonatron high impedance Hang Bo districts, described travelling-wave type thermoacoustic engine thermograde is identical with the thermograde of the standing wave type thermoacoustic engine of described first order thermoacoustic devices.

3. by claim 1 or 2 described tandem type thermoacoustic systems, it is characterized in that the resonatron of described λ/2 acoustic resonator is provided with and is attached thereto logical hollow and annular pipe; The plane at described hollow and annular pipe place is perpendicular to the resonatron of described λ/2 acoustic resonator; The connection intersection point that described hollow and annular pipe is connected with the resonatron of described λ/2 acoustic resonator and the best of described λ/2 acoustic resonator listen between the point of articulation distance to be less than or equal to 1/8 λ, and satisfy formula p _J/ U _J=ρ α/Acot (2 π L/ λ), wherein p _JFor described hollow and annular pipe is communicated with the acoustic pressure of intersection point, U with the resonatron of described λ/2 acoustic resonator _JFor being communicated with the volume flow speed of intersection point place work medium in the resonatron of described λ/2 acoustic resonator, ρ is the averag density of the interior work of the resonatron medium of described λ/2 acoustic resonator, a is the velocity of sound of the interior work of the resonatron medium of described λ/2 acoustic resonator, A is the cross-sectional area of hollow and annular pipe, and L is the length of hollow and annular pipe; The best point of articulation of listening is meant that acoustic pressure is zero point with the hunting speed phase difference in the resonatron.

4. according to the described tandem type thermoacoustic system of claim 3, it is characterized in that, described hollow and annular pipe be shaped as circle, ellipse or rectangle closed-loop path loop pipe.

5. according to the described tandem type thermoacoustic system of claim 3, it is characterized in that the resonatron of described λ/2 acoustic resonator is 2-4 with the caliber of described hollow and annular pipe ratio, described hollow and annular length of tube is 8-20 with the ratio of described hollow and annular caliber.

6. according to claim 1 or 2 described tandem type thermoacoustic systems, it is characterized in that the center of the regenerator in the described travelling-wave type thermoacoustic engine and the λ of this travelling-wave type thermoacoustic engine/2 acoustic resonator are best listens the distance between the point of articulation to be less than or equal to 1/8 λ.

7. according to claim 1 or 2 described tandem type thermoacoustic systems, it is characterized in that the center of the regenerator in the described travelling-wave type hot sound refrigerating machine and the λ of this travelling-wave type hot sound refrigerating machine/2 acoustic resonator are best listens the distance between the point of articulation to be less than or equal to 1/8 λ.

8. according to claim 1 or 2 described tandem type thermoacoustic systems, it is characterized in that, described standing wave type thermoacoustic engine comprises cooler, heater and is positioned at described cooler and the thermoacoustic system of heater centre that it is 0.025 λ-0.3 λ that the best of the center of described thermoacoustic system and λ/2 acoustic resonator is listened the distance between the point of articulation.

9. described thermoacoustic system is that plate stack structure or woven wire are formed, and the 1-2 that its microchannel hydraulic radius is the heat leak layer doubly.

10. the work medium of described λ/2 acoustic resonator is nitrogen, helium, carbon dioxide, argon gas, hydrogen or is the mist of above-mentioned two or more gas compositions.

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