CN1064746C - Thermoacoustic engine - Google Patents

Abstract

A new type of thermoacoustic engine device, which uses the thermoacoustic effect generated by the half-wave resonance or near-resonance sound field to partially convert the thermal energy of the high-temperature heat source into sound energy, and the sound energy is directly used or converted into mechanical energy, electrical energy, and pressure energy Waiting for use. The novel thermoacoustic engine consists of heat exchangers 1, 3, regenerator 2, acoustic wave guides 4, 6, resonance tube 5, microphone 7, acoustic wave guides or guide sets 8, 9 with acoustic impedance regulators. The length of the thermoacoustic engine is about half the wavelength of the sound wave or more than a quarter wavelength and less than half the wavelength. In a thermoacoustic regenerator, the thermoacoustic effects produced by the traveling wave part and the standing wave part of the sound field are both thermoacoustic effects.

Description

thermoacoustic engine

The invention relates to an engine device, in particular to a thermoacoustic engine which converts heat energy into sound energy by using thermoacoustic effect in thermoacoustic effect. The thermoacoustic engine consumes heat energy provided by a high-temperature heat source, and converts heat energy into sound energy through the thermal interaction between the oscillating compressible fluid working medium (sound) and the solid working medium, and the sound energy is directly utilized or converted into mechanical energy , Electric energy, pressure energy, etc. are available for use.

Currently, known thermoacoustic engines are described in US Patent 4,489,553 (Whealley 12/1984). This is a half-wavelength thermoacoustic engine (L ~ 1/2λ, λ is the acoustic wavelength), but they only use the irreversibility of the working medium and the standing wave to produce the thermoacoustic effect, so the intensity of the thermoacoustic effect it produces And the conversion and utilization rate of effective energy is low. Also as described in U.S. Patent 4,114,380 (Ceperley 9/1978), 4,355,517 (Ceperley 10/1982), they use the thermoacoustic effect produced by traveling waves to work, but this is a full-wavelength thermal Acoustic engine (L～λ), the impedance of its acoustic path is not easy to match and it is difficult to realize, so far there is no report of implementation and application.

The object of the invention is to propose a thermoacoustic engine that converts heat energy into sound energy according to the characteristics of energy (sound energy and heat energy) conversion and transportation in thermoacoustic effect on the basis of systematic research on thermoacoustic effect. Acoustic engines can overcome or reduce the shortcomings of previous thermoacoustic engines, and improve the intensity of thermoacoustic effects and the conversion and utilization of effective energy.

Embodiments of the present invention are as follows:

The thermoacoustic engine provided by the present invention includes an ambient temperature thermoacoustic radiator, a thermoacoustic regenerator, a high temperature thermoacoustic heat absorber, a high temperature acoustic waveguide, a thermoacoustic resonant tube, an ambient temperature acoustic waveguide, and a microphone, and is characterized in that: It also includes the acoustic wave main feedback adjustment loop and the acoustic wave secondary feedback adjustment loop composed of acoustic wave guides or acoustic wave guide groups with acoustic impedance regulators. The ambient temperature thermoacoustic radiator and high temperature thermoacoustic heat absorber are respectively located Low-temperature and high-temperature ends, the two ends of the high-temperature acoustic waveguide are respectively connected to the high-temperature thermoacoustic heat absorber and the thermoacoustic resonance tube, and the other end of the thermoacoustic resonance tube is connected to the microphone through the ambient temperature acoustic waveguide, the acoustic waveguide or the acoustic waveguide with the acoustic impedance adjuster One end of the sound wave main feedback regulation loop composed of a group is connected to the ambient temperature thermoacoustic radiator, the other end is connected to the ambient temperature acoustic waveguide between the thermoacoustic resonance tube and the microphone, and the sound wave secondary feedback regulation loop is connected to the thermoacoustic regenerator and Thermoacoustic resonant tube; the sound field in a thermoacoustic engine is a half-wave resonant sound field or a half-wave near-resonant sound field, the length of which is about half the wavelength of the sound wave or between a quarter wavelength and a half wavelength; in a thermoacoustic regenerator In this method, the phase of the velocity fluctuation of the working fluid is ahead of the phase of the pressure fluctuation, and the thermoacoustic effects generated by the traveling wave part and the standing wave part of the sound field are all thermoacoustic effects; the two ends of the thermoacoustic resonance tube are at high temperature and ambient temperature respectively, Part of the acoustic energy flow generated by the thermoacoustic regenerator is fed back to the thermoacoustic regenerator by the main feedback regulation loop of the sound wave, forming a traveling wave acoustic energy flow that runs through the entire thermoacoustic regenerator;

The microphone is an electromagnetic oscillation microphone or generator that converts sound energy into electrical energy, a reciprocating piston microphone that converts sound energy into mechanical energy, a compressor valve group or electromagnetic valve group that converts sound energy into pressure energy, or rotary valve group;

The high-temperature acoustic waveguide, thermoacoustic regenerator, thermoacoustic resonator tube and ambient temperature acoustic waveguide are made of metal pipes or non-metallic pipes, and the layout shapes of their axes are linear, U-shaped, curved, and partially curved; The relative position between the thermoacoustic regenerator and the thermoacoustic resonance tube is arranged coaxially or non-coaxially;

The internal structure of the thermoacoustic regenerator is a laminated structure of solid thin plates forming an acoustic flow channel between plates, or a porous acoustic flow channel formed by stacking wire mesh or a porous solid porous material or granular material. Acoustic channel or a combination of the above three types of structures; the thermoacoustic regenerator is a straight pipe or a variable cross-section pipe that expands from the low temperature end to the high temperature end, and its expansion form is a trumpet-shaped continuous expansion or a trapezoidal step expansion; the thermoacoustic regenerator The heater is insulated from the external heat source;

The thermoacoustic resonant tube is a pipeline with poor axial thermal conductivity, with or without high and low temperature thermoacoustic heat exchangers at both ends to maintain a constant temperature at both ends; the material of the thermoacoustic resonant tube is thin-walled Metal tube or non-metallic tube or composite thin-walled tube whose outer wall is metal and inner wall is non-metallic; the cross-sectional shape of the thermoacoustic resonance tube is a straight tube or a variable-section tube that shrinks from the high temperature end to the low temperature end, and its shrinkage form is Trumpet-shaped continuous shrinkage or trapezoidal stepped shrinkage; the tube of the thermoacoustic resonant tube is filled or partially filled with or not filled with thermoacoustic regenerating materials; both ends of the thermoacoustic resonant tube are provided with or without laminar fluidization elements;

The internal structure of the ambient temperature thermoacoustic heat radiator and high temperature thermoacoustic heat absorber is a laminated structure of solid flat plates with good thermal conductivity, and acoustic flow channels are formed between the plates or solid circular tube groups or integral The sound channel is processed in a solid block or the porous acoustic channel is formed by stacking metal mesh and solid porous materials; the shape of the acoustic channel of the ambient temperature thermoacoustic heat radiator and high temperature thermoacoustic heat absorber is rectangular, circular or Ellipse, triangle, rhombus and hexagon; the solid medium of ambient temperature thermoacoustic heat radiator and high temperature thermoacoustic heat absorber is a solid material with good thermal conductivity;

The acoustic impedance adjuster in the acoustic wave main feedback adjustment loop and the acoustic wave secondary feedback adjustment loop composed of the acoustic waveguide or the acoustic waveguide group with the acoustic impedance adjuster is an acoustic resistance adjuster, an acoustic capacity adjuster or an acoustic sense adjuster or Its combination, the acoustic resistance adjuster is a small section of fine hole tube or a small section of porous medium or a small hole regulating valve or a combination thereof; the sound volume adjuster is a cavity located on the acoustic channel; the acoustic inductance adjuster is A length of slender pipe connected to the channel;

The sound wave sub-feedback adjustment loop is composed of an acoustic waveguide with an acoustic impedance regulator, which is one, two or multiple;

When the relative position between the thermoacoustic regenerator and the thermoacoustic resonant tube is arranged coaxially, the acoustic impedance adjuster in the acoustic wave sub-feedback adjustment loop is one on the common wall of the thermoacoustic regenerator and the thermoacoustic resonant tube , two or more small holes, or adopt or make the common wall into a porous wall;

The sound wave main feedback regulation loop is replaced by a loudspeaker, and its loudspeaker is a component that converts electrical energy, mechanical energy, and pressure energy into sound energy, including piston type, diaphragm type, and airflow type speakers driven by motors or electromagnetic drives. The energy provided by the outside or the part of the energy converted from the sound energy by the microphone.

The thermoacoustic engine that the present invention provides, its sound field adopts the design of half-wave resonant sound field (L～1/2λ) or near-resonant sound field (1/4λ<L<1/2λ), and it rationally utilizes isothermal wall thermoacoustic effect and The characteristics of the thermoacoustic effect of the adiabatic wall, and the thermoacoustic effect of the thermoacoustic effect produced by the traveling wave part of the sound field and the thermoacoustic effect produced by the standing wave part of the sound field, convert heat energy into sound energy. This new type of thermoacoustic engine can overcome the shortcomings of previous thermoacoustic engines that the impedance is not easy to match, cannot obtain enough useful work worth using, or has low energy conversion efficiency, and convert thermal energy into sound energy, or into mechanical energy and electrical energy. Or output such as pressure energy for utilization.

In order to clarify the idea of the present invention, a necessary description of the thermoacoustic effect is given below.

The thermoacoustic effect refers to the time-average thermodynamics between the compressible fluid working medium with thermal expansion and the solid working medium with large heat capacity and thermal conductivity due to the acoustic oscillation and thermal interaction of the fluid relative to the solid. energy effect.

According to the thermal contact mode between the solid outer wall and the external heat source, the thermoacoustic effect can be divided into isothermal wall thermoacoustic effect, adiabatic wall thermoacoustic effect, and general situation thermoacoustic effect.

The isothermal wall thermoacoustic effect means that when the outer wall of the solid working medium is in ideal thermal contact with the external heat source, the average temperature of the solid and the fluid does not change at any point due to the ideal thermal contact, and is the same as the temperature of the external heat source. Time-averaged energy effect of lateral heat exchange between working medium and external heat source. The characteristics of isothermal wall thermoacoustic effect are: 1. In the area of low acoustic conductivity ratio (acoustic conductivity ratio is the ratio of the product of the local fluid density, sound velocity, and velocity fluctuation amplitude to the pressure fluctuation amplitude), the working medium releases heat to the external heat source, 2. In the area of high acoustic conductivity ratio, if the Prandtl number (the ratio of viscosity coefficient to thermal conductivity) of the fluid working medium is small enough, the working medium will absorb heat from an external heat source, 3. When the working medium and the acoustic conductivity ratio are constant, the strength and efficiency of the thermoacoustic effect of the isothermal wall are related to the ratio of the acoustic channel width to the fluid thermal penetration depth. When the equivalent scale of the acoustic channel is equivalent to the fluid thermal penetration depth, it is relatively good.

The thermoacoustic effect of the adiabatic wall refers to that when the outer wall surface of the solid working medium is insulated from the external heat source, due to the result of ideal thermal insulation, the total energy flow (the total energy flow is the sum of the enthalpy flow and the heat flow of heat conduction, which is also equal to the heat and sound work The sum of currents) will remain unchanged, and the time-averaged energy effect of the mutual conversion of heat energy and sound energy will appear. When the thermoacoustic effect of the adiabatic wall produces thermoacoustic effect, the high temperature heat energy is consumed and converted into acoustic energy, and the heat flow is transported from the high temperature end to the low temperature end and released to the environment.

The thermoacoustic effect of the general case occurs when the outer wall surface of the solid working medium is in limited thermal contact with an external heat source. Isothermal wall thermoacoustic effect and adiabatic wall thermoacoustic effect are two limit cases of general case thermoacoustic effect.

Any sound field can be regarded as the sum of the standing wave part and the traveling wave part of the sound field. When thermoacoustic effect of adiabatic wall produces thermoacoustic effect, the effect produced by the standing wave part of the sound field has the following characteristics: 1. The resulting thermoacoustic effect is low in intensity; 2. The direction of heat flow is always from the area with high acoustic conductivity ratio to the area with low acoustic conductivity ratio; 3. When the high temperature end is in the area of high acoustic conductivity ratio and the low temperature end is in the area of low acoustic conductivity ratio, the thermoacoustic effect will be generated when a large temperature gradient is applied. At this time, the heat flow direction flows from the high temperature end to the low temperature end; 4. When the temperature gradient is constant, the strength and efficiency of the thermoacoustic effect of the standing wave part of the sound field is the largest when the equivalent scale of the acoustic channel is about the thermal penetration depth of the fluid. At this time, the fluid working medium has a moderate degree of thermal contact with the solid working medium, and the thermoacoustic effect relies on the limited thermodynamic irreversibility of the working medium. For completely reversible or completely irreversible working media, standing waves cannot produce thermoacoustic effects.

The effects produced by the traveling wave part of the sound field have the following characteristics: 1. The thermoacoustic effect generated is high (for the same pressure and velocity amplitude sound wave, the energy flux density that can be achieved is about twice that of the standing wave); 2. The direction of heat flow is always opposite to the direction of acoustic work flow (direction of traveling wave propagation). And ideally, when the working medium is fully reversible, the heat flow and work flow are equal, and when the working medium is thermodynamically irreversible, the heat flow is smaller than the work flow; 3. When the high-temperature end is in the area of high acoustic conductivity ratio, and the low-temperature end is in the area of low acoustic conductivity ratio, the thermoacoustic effect is generated when the large temperature gradient and heat flow direction flow from the high-temperature end to the low-temperature end. The flow direction flows from the low temperature end to the high temperature end, and part of the heat energy is consumed and converted into sound energy; 4. When the temperature gradient is constant, the intensity and efficiency of the thermoacoustic effect produced by the traveling wave part of the sound field is the largest when the equivalent scale of the acoustic flow channel is small compared with the thermal penetration depth without causing large viscous dissipation. At this time, the fluid working medium has good thermal contact with the solid working medium, and the thermoacoustic effect relies on the thermodynamic reversibility of the working medium. For a fully reversible working medium, the intensity of the thermoacoustic effect generated by traveling waves and the efficiency of energy conversion and utilization are the highest.

The working medium that produces the thermoacoustic effect should be a compressible fluid medium with a higher degree of thermal expansion and a lower Prandtl number, and a solid medium with a larger heat capacity than the fluid medium. Especially for fluid media, where the temperature difference between high and low temperatures is large and the energy flow density is low (such as high temperature heat source and low power thermoacoustic engine), simple molecular formula and small molecular weight can be used. Gases (such as helium, hydrogen, nitrogen, etc.); in occasions where the temperature difference between high and low temperatures is small and the energy flow density is relatively large (such as the temperature of the high-temperature heat source is low and the thermoacoustic engine that requires high power) , gas with relatively simple molecular formula at higher working pressure (such as helium, nitrogen, carbon dioxide, etc.) or a near-critical fluid with simple molecular formula whose critical temperature is near the ambient temperature (such as carbon dioxide, propylene, water, etc. can be used, but The working pressure should be near the critical pressure).

The present invention is realized using the following basic acoustic and thermoacoustic components. Each of these components has different functions, and completes the functions of providing, converting, and transporting sound energy and heat energy in the thermoacoustic engine. These basic components are:

1. sound transducer. The acoustic transducer is a component that realizes the mutual conversion between active energy such as electrical energy, mechanical energy, and pressure energy, and acoustic energy. For example, electromagnetic, piston, and airflow speakers can realize the conversion of active energy and sound energy; electromagnetic oscillation type, reciprocating piston microphone or generator can realize the conversion of sound energy and electric energy, and the reciprocating piston can realize the conversion of sound energy and sound energy. The conversion of mechanical energy, compressor valve group, solenoid valve group or rotary valve group can realize the mutual conversion of sound energy and pressure energy, etc., and they can output the sound energy in the thermoacoustic engine. In the following, transducers that convert other active energy into sound energy are collectively referred to as loudspeakers, and transducers that convert sound into other active energy are collectively referred to as microphones.

2. Thermoacoustic heat exchanger. The thermoacoustic heat exchanger is a component that uses the thermoacoustic effect of the isothermal wall to realize the heat exchange between the thermoacoustic engine and the external heat source. A thermoacoustic heat exchanger placed in a region with a high acoustic conductivity ratio in the sound field of a thermoacoustic engine absorbs heat from an external heat source, called a thermoacoustic heat absorber, and a thermoacoustic heat exchanger placed in a region with a low acoustic conductivity ratio in the sound field of a thermoacoustic engine Heat release to an external heat source is called a thermoacoustic radiator. The structure of the thermoacoustic heat exchanger can be a laminated structure of solid flat plates (such as metal plates) with good thermal conductivity, and flow channels are formed between the plates; solid circular tube groups or sound channels can also be processed in the whole block The structure can also be stacked with wire mesh to form a porous acoustic flow channel or use other types of solid porous materials. In a thermoacoustic heat exchanger, the shape of the acoustic flow channel can be various, such as rectangle, circle or ellipse, triangle, rhombus, hexagon, etc., but the equivalent scale of the acoustic flow channel should be equivalent to the fluid heat penetration depth. The solid medium of the thermoacoustic heat exchanger should have good thermal conductivity, and the outer wall of the solid medium should have good thermal contact with the external heat source, so that the temperature of the entire heat exchanger should be in an isothermal state as much as possible. The length of the heat exchanger should be small compared to the acoustic wavelength, so as to avoid the same heat exchanger going beyond the area of high or low acoustic conductivity ratio, so that the heat absorption or heat release effect is reduced or counteracted.

3. Thermoacoustic regenerator. The thermoacoustic regenerator is a key component to realize the thermoacoustic effect of the thermoacoustic engine and the conversion of heat energy and sound energy by using the thermoacoustic effect of the adiabatic wall. The design of the thermoacoustic regenerator should make the ratio of acoustic conductivity at both ends appropriate, so that the energy transport and conversion can be carried out smoothly, and it can work in harmony with the thermoacoustic heat exchanger. The structure of the thermoacoustic regenerator can be a laminated structure of solid thin plates (such as metal plates), and the acoustic flow channel is formed between the plates; it can also be stacked with metal wire mesh to form a porous acoustic flow channel or other types of solid porous material. In the thermoacoustic regenerator, the shape of the acoustic runner can be various or a combination of various shapes can be used in the same regenerator. However, the equivalent scale of the acoustic channel should be about the thermal penetration depth of the local fluid (in the area where the standing wave sound field accounts for the main part), or much smaller than the thermal penetration depth of the fluid (in the area where the traveling wave sound field accounts for the main part), Or an appropriate value smaller than the fluid penetration depth (in the region where both the standing wave and the traveling wave sound field account for a considerable share). The thermoacoustic regenerator can be a straight pipe, or a variable-section pipe that shrinks from the high temperature end to the low temperature end, such as a trumpet-shaped continuous shrinkage, or a trapezoidal stepped shrinkage. The solid medium of the thermoacoustic regenerator should have better transverse (perpendicular to the direction of sound propagation) thermal conductivity and longitudinal (along the direction of sound propagation) thermal conductivity (this can be achieved with a longitudinally arranged laminated structure), so that the entire regenerator The temperature in the same cross-section should be the same as possible without large longitudinal heat flow loss from the high temperature end to the low temperature end of the regenerator due to heat conduction. The heat capacity of the solid medium on the same cross-section of the regenerator should be much larger than that of the fluid medium, and the thermal contact area between the solid medium and the fluid medium should be large to avoid imperfect thermal contact, which will cause insufficient thermoacoustic effect and lead to incomplete Necessary thermodynamically irreversible losses. The thermoacoustic regenerator and the external heat source should have good thermal insulation to avoid heat leakage to the environment and heat transport loss from the high temperature end to the low temperature end due to the thermoacoustic effect.

4. Thermoacoustic resonance tube. The thermoacoustic resonant tube is a solid pipe whose outer wall is insulated and its two ends are respectively connected to the high and low temperature ends. Its two ends can be equipped with high and low temperature thermoacoustic heat exchangers to maintain a constant temperature at both ends. Its main function is to generate a half-wave resonance or near-resonance sound field in the entire system through the matching of the pipe length in the system, and to connect any two thermoacoustic components working in the high temperature section and the low temperature section without causing relatively Large heat flow loss from high temperature end to low temperature end and attenuation of sound work flow. The acoustic conductivity ratio at both ends of the thermoacoustic resonant tube preferably spans regions of high and low acoustic conductivity ratios. The thermoacoustic resonant tube should adopt a tube with poor thermal conductivity, such as a thin-walled metal tube or a non-metallic tube, or a composite thin-walled tube with a metal outer wall and a non-metallic inner wall. The cross-sectional shape of the thermoacoustic resonance tube can be various, but the equivalent scale of the acoustic flow path should be greater than or much greater than the heat penetration depth of the local fluid to avoid heat flow from the high temperature end to the low temperature end due to solid heat conduction and thermoacoustic effects The loss, but it can't be too large so that the working volume of the whole system is too large and the energy density is too low. The thermoacoustic resonant tube can be a straight tube along the longitudinal direction, or a variable-section tube expanding from the low temperature end to the high temperature end, such as a trumpet-shaped continuous expansion, or a trapezoidal step expansion. The outer wall of the thermoacoustic resonant tube should be thermally insulated from the external heat source as much as possible to avoid heat leakage loss. Both ends of the thermoacoustic resonant tube can be provided with (or not provided with) laminar fluidization elements, so that the flow in the thermoacoustic resonant tube can be as close to laminar flow as possible, and the turbulent mixing loss can be reduced or eliminated.

5. acoustic waveguide. An acoustic waveguide is a section or a group of solid pipes operating at the same or similar temperature. Its function is mainly to connect the two ends of the thermoacoustic engine in the same temperature region to form an acoustic loop (acoustic feedback loop), or to adjust the natural frequency of the system.

6. Acoustic impedance adjuster. The acoustic impedance adjuster is a component that adjusts and matches the acoustic impedance. It can be used to adjust and match the magnitude and phase of the local acoustic oscillation (velocity and pressure fluctuations) in the appropriate position in the thermoacoustic engine. There are three types of impedance in acoustics, acoustic resistance, acoustic capacitance, and acoustic perception, so there are three basic types of acoustic impedance regulators. The acoustic resistance adjuster (or acoustic damping adjuster) can be a small section of fine (micro) hole tube or a small section of porous medium or a small hole regulating valve or a combination thereof. The acoustic capacitive reactance regulator is connected to a larger cavity on the acoustic channel. The acoustic inductance adjustment is generally connected to a long and thin pipe on the acoustic channel. In actual use, these three basic regulators can be used alone or in combination in parallel or in series to obtain the desired acoustic oscillation at a specific position in the sound path and adjust the amplitude and phase of the sound field at a certain position.

The thermoacoustic engine referred to in the present invention is composed of the above several basic acoustic and thermoacoustic components. Different selections and combinations of these components form thermoacoustic engines with different structural characteristics. The different options and combinations referred to here all need to meet the condition that a thermoacoustic engine includes at least the above basic components; at the high temperature end, the thermoacoustic heater is transported from the high temperature end of the outside to the low temperature end; In the thermoacoustic regenerator, the thermoacoustic effect produced by the traveling wave part and the standing wave part of the sound field is the thermoacoustic effect, that is, the heat energy is converted into sound energy. At this time, the acoustic work flow is transported from the low temperature end to the high temperature end. The heat flow is transported from the high-temperature end to the low-temperature end; at the low-temperature end, the thermoacoustic heat exchanger releases heat to the external low-temperature heat source; the sound field in the entire thermoacoustic engine is a half-wave resonant sound field or a near-resonant sound field, and the resonance of the sound field depends on The thermoacoustic resonance tube is matched with the acoustic waveguide; the traveling wave component of the sound field is generated by a speaker or an acoustic feedback loop with an acoustic impedance regulator.

By adopting the above design, the performance of the thermoacoustic engine can be greatly improved, the loss of useful energy can be reduced, and the efficiency of the thermoacoustic engine can be improved. Furthermore, due to the flexible design, we can choose the combination of different types of transducers and other parts with different characteristics according to the situation, so as to meet the needs of different occasions.

Further describe the present invention below in conjunction with accompanying drawing and embodiment:

Accompanying drawing 1 is the structural representation of the thermoacoustic engine of the present invention that only adopts a transducer (microphone), and arrow point among the figure is the direction of sound work flow;

Accompanying drawing 2 is the structure schematic diagram of the thermoacoustic engine that adopts loudspeaker to replace the main feedback loop of sound wave in the structure of Fig. 1, and it adopts two transducers (dual drive), namely a microphone and a loudspeaker. The arrows in the figure indicate the direction of the sound work flow;

Ambient temperature thermoacoustic radiator 1 thermoacoustic regenerator 2 high temperature thermoacoustic absorber 3

High temperature acoustic waveguide 4 Thermoacoustic resonance tube 5 Ambient temperature acoustic waveguide 6

Microphone 7 Primary acoustic feedback adjustment loop 8 Secondary acoustic feedback adjustment loop 9

As can be seen from the figure, the thermoacoustic engine provided by the present invention includes an ambient temperature thermoacoustic radiator 1, a thermoacoustic regenerator 2, a high-temperature thermoacoustic heat absorber 3, a high-temperature acoustic waveguide 4, a thermoacoustic resonance tube 5, and an ambient temperature The acoustic waveguide 6 and the microphone 7 are characterized in that: they also include an acoustic waveguide with an acoustic impedance regulator or an acoustic waveguide group composed of an acoustic wave main feedback adjustment loop 8 and an acoustic wave secondary feedback adjustment loop 9, an ambient temperature thermoacoustic radiator 1 and The high-temperature thermoacoustic heat absorber 3 is respectively located at the low-temperature and high-temperature ends of the thermoacoustic regenerator 2, and the two ends of the high-temperature acoustic waveguide 4 are respectively connected to the high-temperature thermoacoustic heat absorber 3 and the thermoacoustic resonance tube 5, and the other end of the thermoacoustic resonance tube 5 One end is connected to the microphone 7 through the ambient temperature acoustic waveguide 6, and one end of the acoustic wave main feedback regulation loop 8 composed of the acoustic waveguide with the acoustic impedance regulator or the acoustic waveguide group is connected to the ambient temperature thermoacoustic heat radiator 1, and the other end is connected to the thermoacoustic resonance On the ambient temperature acoustic waveguide 6 between the tube 5 and the microphone 7, the acoustic sub-feedback regulation loop 9 connects the thermoacoustic regenerator 2 and the thermoacoustic resonance tube 5; the sound field in the thermoacoustic engine is a half-wave resonant sound field or a half-wave near Resonant sound field, the length of which is about half the wavelength of the sound wave or between a quarter wavelength and a half wavelength; in a thermoacoustic regenerator, the phase of the working fluid velocity fluctuation is ahead of the phase of the pressure fluctuation, and the traveling wave part of the sound field The thermoacoustic effect produced by the standing wave part and the standing wave part are both thermoacoustic effects; the two ends of the thermoacoustic resonance tube are at high temperature and ambient temperature respectively, and a part of the acoustic energy flow generated by the thermoacoustic regenerator is controlled by the main feedback loop of the acoustic wave Feedback to the thermoacoustic regenerator to form a shape wave acoustic energy flow that runs through the entire thermoacoustic regenerator;

The microphone 7 is an electromagnetic oscillation microphone or generator that converts sound energy into electrical energy, a reciprocating piston microphone that converts sound energy into mechanical energy, and a compressor valve group or electromagnetic valve group that converts sound energy into pressure energy. or rotary valve group;

The high-temperature acoustic waveguide 4, the thermoacoustic regenerator 2, the thermoacoustic resonator tube 5 and the ambient temperature acoustic waveguide 6 are made of metal pipes or non-metallic pipes, and the layout shapes of their axes are linear, U-shaped, curved, Partially curved; the relative position between the thermoacoustic regenerator 2 and the thermoacoustic resonance tube 5 is arranged coaxially or non-coaxially;

The internal structure of the acoustic engine thermoacoustic regenerator 2 is a solid thin plate laminated structure forming an acoustic flow channel between plates or a porous acoustic flow channel formed by stacking wire mesh or solid porous material or granular material The formed porous acoustic flow channel or its combination; the thermoacoustic regenerator is a straight pipe or a variable cross-section pipe expanding from the low temperature end to the high temperature end, and its expansion form is a trumpet-shaped continuous expansion or a trapezoidal step expansion; the thermoacoustic reheating The device is insulated from the external heat source;

The thermoacoustic resonance tube 5 is a pipeline with poor axial thermal conductivity, and its two ends are equipped with high and low temperature thermoacoustic heat exchangers to maintain a constant temperature at both ends; the material of the thermoacoustic resonance tube is thin-walled metal Tube or non-metallic tube or composite thin-walled tube whose outer wall is metal and whose inner wall is non-metallic; the cross-sectional shape of the thermoacoustic resonance tube is a straight tube or a variable-section tube that shrinks from the high temperature end to the low temperature end, and its contraction form is a horn Shaped continuous shrinkage or trapezoidal stepwise shrinkage; the tube of the thermoacoustic resonant tube is filled or partially filled with or not filled with thermoacoustic regenerating materials; both ends of the thermoacoustic resonant tube are provided with or without laminar fluidization elements;

The internal structure of the ambient temperature thermoacoustic heat radiator 1 and the high temperature thermoacoustic heat absorber 3 is a laminated structure of solid flat plates with good thermal conductivity, and acoustic flow channels are formed between the plates or solid circular tube groups are used Or the structure in which the acoustic channel is processed in the whole solid, or the porous acoustic flow channel is formed by stacking metal mesh and solid porous materials; the shape of the acoustic flow channel of the ambient temperature thermoacoustic radiator and high temperature thermoacoustic heat absorber is rectangular, Round or elliptical, triangular, rhombus and hexagonal; the solid medium of ambient temperature thermoacoustic radiator and high temperature thermoacoustic heat absorber is a solid material with good thermal conductivity;

The acoustic impedance adjuster in the acoustic wave main feedback adjustment loop 8 and the acoustic wave secondary feedback adjustment loop 9 composed of the acoustic waveguide or the acoustic waveguide group with the acoustic impedance adjuster is an acoustic resistance adjuster, an acoustic capacity adjuster or an acoustic adjustment The acoustic resistance adjuster is a small section of fine-pore tube or a small section of porous medium or a small-hole regulating valve or a combination thereof; the sound volume adjuster is a cavity located on the acoustic channel; the acoustic inductance adjuster is a length of slender pipe connected to the acoustic channel;

The acoustic wave sub-feedback adjustment loop 9 is composed of an acoustic waveguide with an acoustic impedance regulator, which is one, two or multiple;

When the relative position between the thermoacoustic regenerator 2 and the thermoacoustic resonant tube 5 is arranged coaxially, the acoustic impedance adjuster in the acoustic wave sub-feedback adjustment loop 9 is the common wall of the thermoacoustic regenerator and the thermoacoustic resonant tube One, two or more small holes on the wall, or this common wall is adopted or made into a porous wall;

The sound wave main feedback regulation circuit 8 is replaced by a loudspeaker; its loudspeaker is a component that converts electrical energy, mechanical energy, and pressure energy into acoustic energy, including piston type, diaphragm type, and airflow type speakers driven by motors or electromagnetic drives. The energy of the loudspeaker is provided by the outside world or part of the energy converted from the sound energy by the microphone.

The thermoacoustic engine in Fig. 1, the thermoacoustic heater 2 that utilizes the thermoacoustic effect produced by the traveling wave and the standing wave part of the sound field to convert part of the heat absorbed by the high-temperature thermoacoustic heat absorber 3 from the external high-temperature heat source It is sound energy, and the other part is released to the ambient low-temperature heat source by the thermoacoustic radiator 1 . The acoustic waveguide 4 working at the high-temperature end realizes the connection between the high-temperature thermoacoustic heat absorber 3 and the thermoacoustic resonant tube 5. The thermoacoustic resonant tube 5 is used to transmit the acoustic wave energy from the high temperature to the ambient temperature end, and then through the acoustic waveguide 6 by the microphone 7 Convert sound energy into active energy output such as electrical energy, mechanical energy, and pressure energy for use (it can also directly output sound energy for use as a thermoacoustic speaker). The acoustic waveguide 8 with the acoustic impedance regulator is used to form the main feedback adjustment loop of the acoustic wave to adjust the acoustic field in the thermoacoustic regenerator 2 and match the acoustic impedance so that each thermoacoustic component works in a good state. The length and impedance of the entire main feedback loop should be selected so that the direction of the traveling wave flows to one end of the thermoacoustic regenerator and the system works in an optimal state. The acoustic waveguide or conduit group 9 with an acoustic impedance regulator is used for the connection between the thermoacoustic regenerator 2 and the middle position of the thermoacoustic resonant tube 5, forming a sub-feedback adjustment loop of one or more acoustic waves, so that the thermoacoustic reheating The working efficiency of the device is brought into full play. The acoustic waveguide 6 is used to match the acoustic impedance of the end and the impedance of the microphone 7, and make the low-temperature end of the thermoacoustic resonance tube 5 work in a region with a low acoustic conductivity ratio, so that the sound energy can be converted smoothly and the system can work normally. The length of the entire thermoacoustic engine should be approximately equal to half the wavelength of the sound wave or greater than a quarter wavelength of the sound wave and less than half the wavelength of the sound wave to ensure that the phase of the sound field velocity fluctuation is ahead of the phase of the pressure fluctuation in the thermoacoustic regenerator , the thermoacoustic effect produced by the traveling wave part and the standing wave part of the sound field is a thermoacoustic effect, that is, heat energy is converted into sound energy.

The thermoacoustic engine in Fig. 2 replaces the structure of the sound wave main feedback loop 8 in Fig. 1 with the loudspeaker 10, and the acoustic waveguide 11 is used to match the acoustic impedance of the thermoacoustic radiator and the impedance of the loudspeaker 10, so that the mechanical energy in the loudspeaker 10 etc. can be smoothly converted into acoustic energy, and make the low-temperature thermoacoustic radiator 1 work in the area of low acoustic conductivity ratio. The movement phase of the fluid in the loudspeaker 10 should be coordinated with the movement phase of the fluid in the microphone 7, and the selection of this phase should ensure that the sound work flow is passed through the heater 2 and the thermoacoustic resonance tube 5 to the microphone 7 by the loudspeaker 10 in the system, and makes The whole system works at its best. The functions of other components in the figure are the same as those of the corresponding components in the structure of Fig. 1 . In this structure, the energy microphone 7 driving the operation of the speaker 10 is provided. Here, the length of the entire thermoacoustic engine from the sound source of the speaker to the sound absorber is equal to or approximately less than half the wavelength of the sound wave, so as to ensure the thermoacoustic effect produced by the traveling wave part and the standing wave part of the sound field in the thermoacoustic regenerator Both produce a thermoacoustic effect, converting heat energy into sound energy.

The thermoacoustic regenerator and thermoacoustic resonant tube working in the same temperature range in the above-mentioned thermoacoustic engine can be made into a coaxial structure to increase the compactness of the device.

Claims (10)

1. A thermoacoustic engine, comprising an ambient temperature thermoacoustic radiator, a thermoacoustic regenerator, a high temperature thermoacoustic heat absorber, a high temperature acoustic waveguide, a thermoacoustic resonance tube, an ambient temperature acoustic waveguide, and a microphone, characterized in that it also includes The acoustic wave main feedback adjustment loop and the acoustic wave secondary feedback adjustment loop are composed of acoustic wave guides or acoustic wave guide groups with acoustic impedance regulators, and the ambient temperature thermoacoustic heat radiator and high temperature thermoacoustic heat absorber are respectively located at the low temperature and low temperature of the thermoacoustic regenerator. The high-temperature end, the two ends of the high-temperature acoustic waveguide are respectively connected to the high-temperature thermoacoustic heat absorber and the thermoacoustic resonance tube, and the other end of the thermoacoustic resonance tube is connected to the microphone through the ambient temperature acoustic waveguide, and the acoustic waveguide or the acoustic waveguide group with the acoustic impedance regulator One end of the sound wave main feedback regulation loop is connected to the ambient temperature thermoacoustic radiator, the other end is connected to the ambient temperature acoustic waveguide between the thermoacoustic resonance tube and the microphone, and the sound wave secondary feedback regulation loop is connected to the thermoacoustic regenerator and the thermoacoustic Resonant tube; the sound field in a thermoacoustic engine is a half-wave resonant sound field or a half-wave near-resonant sound field, the length of which is about half the wavelength of the sound wave or between a quarter wavelength and a half wavelength; in a thermoacoustic regenerator, The phase of the velocity fluctuation of the working fluid is ahead of the phase of the pressure fluctuation, and the thermoacoustic effect generated by the traveling wave part and the standing wave part of the sound field are all thermoacoustic effects; Part of the acoustic energy flow generated by the acoustic regenerator is fed back to the thermoacoustic regenerator by the main feedback regulation loop of the sound wave, forming a traveling wave acoustic energy flow that runs through the entire thermoacoustic regenerator. 2. The thermoacoustic engine according to claim 1, wherein the microphone is an electromagnetic oscillator microphone or generator that converts sound energy into electrical energy, a reciprocating piston microphone that converts sound energy into mechanical energy, and converts sound energy into pressure. Capable compressor valve group or solenoid valve group or rotary valve group. 3. The thermoacoustic engine according to claim 1, characterized in that: the high-temperature acoustic waveguide, the thermoacoustic regenerator, the thermoacoustic resonance tube and the ambient temperature acoustic waveguide are made of metal pipes or non-metallic pipes, and the arrangement shape of the axis has a straight line Shaped, U-shaped, curved, partially curved; the relative position between the thermoacoustic regenerator and the thermoacoustic resonant tube is coaxial or non-coaxial. 4. The acoustic engine according to claim 1, characterized in that the internal structure of the thermoacoustic regenerator is a solid thin plate laminate structure forming an acoustic flow channel between plates or a porous acoustic flow channel formed by stacking metal wire mesh Or a porous acoustic flow channel formed by solid porous material, granular material or a combination of the above three types of structures; the thermoacoustic regenerator is a straight tube or a variable-section tube that expands from the low temperature end to the high temperature end, and its expansion form is a trumpet-shaped continuous Expansion or trapezoidal step expansion; thermoacoustic regenerator is insulated from external heat source. 5. The thermoacoustic engine according to claim 1, characterized in that: the thermoacoustic resonant tube is a tube with poor axial thermal conductivity, and its two ends are equipped with or not provided with high and low temperature thermoacoustic exchangers to maintain a constant temperature at both ends. Heater; the material of the thermoacoustic resonance tube is a thin-walled metal tube or non-metallic tube or a composite thin-walled tube whose outer wall is metal and the inner wall is non-metallic; the cross-sectional shape of the thermoacoustic resonance tube is a straight tube or from the high temperature end to The variable cross-section tube that shrinks at the low temperature end, and its shrinkage form is trumpet-shaped continuous shrinkage or trapezoidal stepwise shrinkage; the tube of the thermoacoustic resonance tube is filled or partially filled with or not filled with thermoacoustic reheating materials; the two ends of the thermoacoustic resonance tube are set or Laminarization elements are not provided. 6. The thermoacoustic engine according to claim 1, characterized in that: the internal structure of the ambient temperature thermoacoustic heat radiator and the high temperature thermoacoustic heat absorber is a laminated structure of solid flat plates with good thermal conductivity, and between the plates Acoustic flow channel is formed or the sound channel is processed in a solid circular tube group or a solid block, or a porous acoustic flow channel is formed by stacking metal mesh and solid porous materials; ambient temperature thermoacoustic heat radiator and high temperature thermoacoustic absorber The shape of the acoustic flow channel of the heater is rectangular, circular or elliptical, triangular, rhombus and hexagonal; the solid medium of the ambient temperature thermoacoustic radiator and high temperature thermoacoustic heat absorber is a solid material with good thermal conductivity. 7. The thermoacoustic engine according to claim 1, characterized in that: the acoustic impedance regulator in the acoustic wave main feedback adjustment loop and the acoustic wave secondary feedback adjustment loop formed by the acoustic waveguide or the acoustic waveguide group with the acoustic impedance adjuster is an acoustic impedance adjustment Acoustic volume adjuster or acoustic sense adjuster or its combination, the acoustic resistance adjuster is a small section of fine hole tube or a small section of porous medium or a small hole regulating valve or a combination thereof; the sound volume adjuster is located on the acoustic channel A cavity; the acoustic reactance adjuster is a length of slender pipe connected to the acoustic channel. 8. The thermoacoustic engine according to claim 1, characterized in that: the acoustic wave sub-feedback adjustment loop is composed of an acoustic waveguide with an acoustic impedance adjuster, which is one, two or multiple. 9. The thermoacoustic engine according to claim 1, characterized in that: when the relative position between the thermoacoustic regenerator and the thermoacoustic resonant tube is coaxially arranged, the acoustic impedance regulator in the acoustic wave sub-feedback adjustment loop is a thermoacoustic One, two or more small holes on the common wall of the acoustic regenerator and the thermoacoustic resonance tube, or the common wall is adopted or made into a porous wall. 10. According to the described thermoacoustic engine of claim 1, it is characterized in that: the sound wave main feedback regulation loop is replaced by a loudspeaker; Its loudspeaker is the component that converts electric energy, mechanical energy, pressure energy into sound energy, comprises the piston type of motor drive or electromagnetic drive , Diaphragm type, airflow type speaker, the energy driving the speaker is provided by the outside or part of the energy converted from the sound energy by the microphone.

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