CN103147947B - thermoacoustic generator - Google Patents

Abstract

A thermoacoustic generator, the thermoacoustic generator includes an isotope heat source, a regenerator, a main cold end heat exchanger, an acoustic cavity, an acoustic feedback tube, and a permanent magnet motor, and the permanent magnet motor includes permanent magnets and Surrounding the coil outside the permanent magnet, the regenerator, the main cold end heat exchanger, the acoustic cavity and the acoustic power feedback tube are connected in sequence, and the isotope heat source and the main cold end heat exchanger make the two ends of the regenerator A temperature gradient is formed, and thermoacoustic self-excited oscillations that convert heat energy to acoustic energy are formed in the regenerator, thereby generating self-excited oscillation sound pressure, which drives the permanent magnet in the permanent magnet motor to reciprocate, thereby An induced potential is formed in the coil. The present invention uses the sound pressure generated by the self-excited oscillation of the thermoacoustic heat engine to provide the driving force for the motion of the permanent magnet to generate an induced potential. Since the driving force for the motion of the permanent magnet is provided by the self-excited oscillation of the thermoacoustic engine, the thermoacoustic engine does not move components and therefore have a high degree of reliability.

Description

thermoacoustic generator

technical field

The invention belongs to the technical field of generators, in particular to a thermoacoustic generator.

Background technique

Electric energy is one of the most important energy sources in modern society, and most other energy sources, such as fossil energy represented by coal, oil and natural gas, water energy, wind energy, nuclear energy, etc., need to be converted into electrical energy by generators before being used by people . There are many forms of generators, and the working principle is based on the principle of electromagnetic induction. The magnetic field and electric field capable of electromagnetic induction are formed in a certain way, so as to achieve the purpose of energy conversion.

At present, conventional generators have been developed relatively well, but in some extreme environments, conventional generators cannot work effectively for a long time. For example, when conducting deep space exploration, due to the long detection time, the probe cannot carry enough fuel, and because it is far away from the sun, it cannot use solar cells to obtain sufficient power. At this time, a high-reliability, long-life , Unconventional fuel generators. Another example is that some long-term field detectors and submarine detectors cannot be maintained and fueled due to the harsh working environment. At this time, a one-time injection of fuel is required to ensure long-term and stable operation. A generator powered by isotope decay energy is a possible option. The isotope decay process can be very long (plutonium-238 has a half-life of 87 years), which can provide a steady thermal energy input to a generator for decades to produce a stable electrical energy output. However, there are the following major problems in driving existing generators directly by isotope decay energy: the hot end of existing generators has a moving part called a piston, and a dynamic seal is used between the piston and the cylinder. Due to the presence of lateral force, the sealing The ring rubs against the cylinder directly, and their high-speed relative motion will cause wear, which will affect the life of the motor and power generation efficiency, and some other moving parts also need to be lubricated, which makes the generator must be maintained within a few thousand hours. Obviously can't adapt to the use of described special occasion.

Contents of the invention

(1) Technical problems to be solved

The technical problem to be solved by the present invention is: the existing generator uses chemical fuel, and has moving parts located in a high-temperature environment, and its piston and cylinder have direct mechanical friction, and high-speed relative motion will cause wear and tear, and it is necessary to add fuel and Regular maintenance is not suitable for long-term unattended environments including deep space exploration, seabed exploration, and field fixed-point surveys.

(2) Technical solution

In order to solve the above technical problems, the present invention provides a thermoacoustic generator.

Wherein, the thermoacoustic generator includes an isotope heat source, a regenerator, a main cold end heat exchanger, an acoustic cavity, an acoustic power feedback tube and a permanent magnet motor, and the permanent magnet motor includes a permanent magnet and is surrounded by a permanent magnet The coil of the regenerator, the main cold end heat exchanger, the acoustic cavity and the acoustic power feedback tube are connected in sequence, and the isotope heat source and the main cold end heat exchanger make the two ends of the regenerator form a temperature gradient. The thermoacoustic self-excited oscillation that converts heat energy to sound energy is formed in the regenerator, thereby generating self-excited oscillation sound pressure, which drives the permanent magnet in the permanent magnet motor to reciprocate, thereby forming an induction in the coil electric potential.

Preferably, the outlet end of the sound power feedback tube is provided with a sound pressure output port, and a cylinder with a piston is provided between the sound pressure output port and the permanent magnet motor, and the permanent magnet in the permanent magnet motor is connected to the cylinder. The piston is connected, and the sound pressure output by the sound pressure output port drives the piston to move, thereby driving the permanent magnet to move.

Preferably, the gap between the piston and the cylinder is 5-30 microns.

Preferably, the heat provided by the heat source is transferred to the regenerator through the heat exchanger at the hot end, and the sound pressure output port is connected with a heat exchanger at the sub-cool end, and the heat exchanger at the sub-cool end communicates with the heat exchanger through a heat buffer tube. The hot end heat exchanger, regenerator, main cold end heat exchanger, acoustic cavity, acoustic power feedback tube, sound pressure output port, secondary cold end heat exchanger and thermal buffer tube form a closed loop.

Preferably, the main cold end heat exchanger is an air-cooled or water-cooled heat exchanger.

Preferably, the permanent magnet is connected to the piston through a main shaft, the main shaft is fixedly connected to a plate spring in the permanent magnet motor, and the main shaft is supported by the plate spring.

Preferably, the isotope heat source is plutonium-238 or polonium-210.

Preferably, the isotope heat source is provided with a thermal control device for controlling the temperature generated by the isotope heat source.

Preferably, the casing of the permanent magnet motor is a closed casing.

Preferably, a wire mesh or plate stack is provided in the regenerator.

(3) Beneficial effects

The above technical solution has the following advantages: the generator of the present invention forms a temperature gradient at both ends of the regenerator through the isotope heat source and the main cold end heat exchanger, and forms a thermoacoustic self-excited conversion from heat energy to acoustic energy in the regenerator. Oscillation, thus generating self-oscillating sound pressure, the self-oscillating sound pressure drives the permanent magnet in the permanent magnet motor to reciprocate, thereby forming an induced potential in the coil. In the present invention, the sound pressure generated by the self-excited oscillation of the thermoacoustic engine is used to provide the driving force for the motion of the permanent magnet in the permanent magnet motor to generate an induced potential. Since the driving force for the motion of the permanent magnet is provided by the self-excited oscillation of the thermoacoustic engine, the thermal The acoustic engine has no moving parts and is therefore highly reliable. Moreover, the thermoacoustic system is a traveling wave thermoacoustic system, so that the thermoacoustic conversion efficiency is high. The moving parts of the permanent magnet motor are in a normal temperature environment, and there is a small gap between the piston and the cylinder, so there is no failure caused by high temperature and wear, and the operating life is long.

Description of drawings

Fig. 1 is a schematic structural view of an embodiment of the present invention.

Among them, 100: isotope heat source; 101: isotope decay body; 102: thermal control device; 103: heat output interface; 200: thermoacoustic engine; 201: hot end heat exchanger; 202: regenerator; 203: main cold end Heat exchanger; 204: Acoustic cavity; 205: Acoustic power feedback tube; 206: Acoustic pressure output port; 207: Secondary cooling end heat exchanger; 208: Thermal buffer tube; 300: Permanent magnet motor; 301: Cylinder; 302 : Coil; 303: Support plate; 304: Main shaft; 305: Pressure-bearing shell; 306: Permanent magnet; 307: Magnetic stator; 308: Piston.

Detailed ways

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

As shown in Figure 1, it is a schematic structural diagram of an embodiment of the present invention, the thermoacoustic generator includes an isotope heat source 100, a regenerator 202, a main cold end heat exchanger 203, an acoustic cavity 204, and an acoustic power feedback tube 205 And the permanent magnet motor 300, the permanent magnet motor 300 includes a permanent magnet 306 and a coil 302 surrounding the permanent magnet, the regenerator 202, the main cold end heat exchanger 203, the acoustic cavity 204 and the acoustic feedback tube 205 in turn connected, the isotope heat source 100 and the main cold end heat exchanger 203 make the two ends of the regenerator 202 form a temperature gradient, and form a thermoacoustic self-excited oscillation in which heat energy is converted into acoustic energy in the regenerator 202, thereby generating self-excited oscillation Sound pressure, the self-oscillating sound pressure drives the permanent magnet 306 in the permanent magnet motor 300 to reciprocate, thereby forming an induced potential in the coil 302 . In the thermoacoustic engine of the present invention, when the temperature gradient at both ends of the regenerator 202 reaches 8000° C./m or above, the thermoacoustic engine 200 of the closed acoustic loop formed by the acoustic cavity 204 and the acoustic power feedback pipe 205 and the permanent magnet The thermoacoustic self-excited oscillation is formed in the motor 300, and the oscillating sound pressure drives the high-pressure gas working medium filled in the thermoacoustic engine 200 and the permanent magnet motor 300 to alternately flow, realizing the conversion of thermal energy to acoustic energy (thermoacoustic) . The generator uses sound waves to drive the permanent magnets in the permanent magnet motor to move, thereby generating an induced electromotive force in the coil. Since the sound pressure driving the motion of the permanent magnet is generated by the thermoacoustic engine 200 with no moving parts, it has a high degree of reliability. Moreover, the thermoacoustic system is a traveling wave thermoacoustic system, so that the thermoacoustic conversion efficiency is high. The moving parts of the permanent magnet motor are in a normal temperature environment, and there is a small gap between the piston and the cylinder, so there is no failure caused by high temperature and wear, and the operating life is long.

The isotope heat source of the present invention can be provided by using various suitable isotopes, and the heat source can also be provided by direct heating. Preferably, the heat source is provided by the isotope decay body 101, and the isotopes used to provide the heat source may be plutonium-238, polonium-210, and the like. The invention adopts the isotope as the heat source, which can improve the service life of the heat source, and can realize the long-term stable supply of heat energy under unattended conditions. For example, when plutonium-238 with a long half-life (87.6 years) is used as the isotope decay body, it can ensure that the isotope heat source can continuously provide sufficient heat energy for 10 years. In order to ensure that the temperature of the heat source will not be too high, a heat control device 102 is arranged on the isotope heat source 100 to control the temperature of the isotope heat source. The heat control device can be various existing temperature control devices, which are existing The technology will not be described in detail here. In order to output heat energy from the isotope heat source 100 , a heat output interface 103 is installed in the isotope heat source 100 , and the heat of the heat source is introduced into the heat end heat exchanger 203 at one end of the regenerator 202 through the heat output interface 103 . The heat output interface 103 can adopt various suitable heat conductors, such as metal copper, aluminum and so on.

The thermoacoustic engine 200 of the present invention is used to generate thermoacoustic self-excited oscillation, convert heat energy into sound energy, and drive the permanent magnet 306 in the permanent magnet motor 300 to reciprocate through the oscillating sound wave, thereby forming an induced potential in the coil 302 . The thermoacoustic engine 200 of the embodiment shown in Figure 1 includes a hot end heat exchanger 201, a regenerator 202, a main cold end heat exchanger 203, an acoustic cavity 204, an acoustic power feedback tube 205, a sound pressure output port 206, a secondary Cold end heat exchanger 207 and thermal buffer pipe 208, preferably, hot end heat exchanger 201, regenerator 202, main cold end heat exchanger 203, acoustic cavity 204, acoustic power feedback pipe 205, sound pressure output port 206 , the sub-cooling end heat exchanger 207 and the heat buffer pipe 208 form a closed loop. Wherein, the two ends of the regenerator 202 are respectively a hot end heat exchanger 201 and a main cold end heat exchanger 203, and the hot end heat exchanger 201 is connected with the heat output interface 103 of the isotope heat source 100 to obtain heat from the isotope heat source 100 To maintain a higher temperature, the main cold end heat exchanger 203 releases heat to the outside to maintain a lower temperature, thereby forming a large temperature gradient at both ends of the regenerator 202, and the cooling method of the main cold end heat exchanger 203 can be adopted Water cooling or air cooling. When the temperature gradient at both ends of the regenerator 202 reaches 8000°C/m or above, the self-excited oscillation pressure will be generated in the thermoacoustic engine 200, and the gas is driven by the alternating pressure in the regenerator 202 with a temperature difference. Micro-thermodynamic cycle to realize the conversion of heat energy to sound energy (thermoacoustic). The gas passes through the acoustic cavity 204 and the acoustic power feedback tube 205 for self-excited oscillation and then is output to the permanent magnet motor 300 from the sound pressure output port 206 , thereby providing driving force for the permanent magnet 306 in the permanent magnet motor 300 to move. In the regenerator 202 of this embodiment, a wire mesh or plate stack is added, such as a wire mesh or a stack of metal sheets with poor thermal conductivity, and the hydraulic radius in the regenerator 202 is smaller than that of the gas working fluid. The depth of the heat penetration layer realizes the reversible heat exchange between gas and solid in the regenerator 202, which ensures the high efficiency of the thermoacoustic engine, which is why the present invention adopts the traveling wave thermoacoustic engine. The thermoacoustic engine 200 converts heat into sound power, has no moving parts, has a service life of up to 10 years, and has a thermoacoustic conversion efficiency of 20%-30%.

The acoustic chamber 204 and the acoustic power feedback tube 205 of this embodiment provide the environment for the self-excited oscillation of the acoustic power. Both the acoustic chamber 204 and the acoustic power feedback pipe 205 can be made up of metal pipes of various shapes. It can be set according to needs. Generally, the diameter of the acoustic cavity 204 is larger than that of the acoustic feedback tube 205, thereby providing the closed space required for the acoustic vibration in the thermoacoustic engine 200 and maintaining a higher pressure environment than the outside world. In order to ensure that the gas temperature of the sound pressure output interface 206 is maintained at room temperature, the sound pressure output interface 206 is provided with a secondary cold end heat exchanger 207 and a thermal buffer tube 208, and the thermal buffer tube 208 is connected with the hot end heat exchanger 201, The heat buffer pipe 208 is composed of a section of metal pipe, and the subcooler heat exchanger 207 can also be cooled by water cooling or air cooling. This structure realizes thermal isolation between the sound pressure output interface 206 and the hot end heat exchanger 201 by utilizing the poor thermal conductivity of the gas working fluid.

Driven by sound waves, the permanent magnet motor 300 of the present invention generates induced potential on the coil through the movement of the permanent magnet, and utilizes the principle of electromagnetic induction to generate electricity. The permanent magnet motor 300 can adopt various existing motors. The permanent magnet motor of this embodiment includes a coil 302, a pressure-bearing shell 305, a permanent magnet 306 and a magnetically permeable stator 307, and a magnetically permeable stator is provided around the permanent magnet 306. 307 , a coil 302 is passed through the magnetically permeable stator 307 , and a pressure-bearing shell 305 is provided outside the magnetically permeable stator 307 . The permanent magnet 306 is made of magnetic material capable of maintaining magnetism for a long time, and its linear reciprocating motion can generate alternating magnetic flux changes on the coil plane. The magnetically permeable stator 307 can be made of silicon steel sheets stacked and then pressed to form a passage for the magnetic force lines inside the permanent magnet motor. The pressure-bearing shell 305 can be made of metal and sealed to ensure that the air inside the permanent magnet motor is isolated from the outside air and can withstand the high-pressure gas charged.

The cylinder 301 of the permanent magnet motor 300 of the embodiment shown in Figure 1 is directly connected on the sound pressure output port 206, and the piston 308 that is connected with the permanent magnet 306 is arranged in the cylinder 301, and the permanent magnet 306 is connected with the piston 308 by the main shaft 304 . In order to ensure good alignment between the piston 308 and the cylinder 301, a plate spring 303 is provided in the permanent magnet motor 300, which is fixedly connected with the main shaft 304 and can be made of stainless steel metal plate. Preferably, the radial direction of the plate spring 303 The ratio of stiffness to axial stiffness is 300-800. Since the main shaft 304 is fixedly connected to the plate spring 303, there is no lateral force between the piston 308 and the cylinder 301, no direct mechanical friction, and no wear and tear failure, thereby prolonging the service life. In this embodiment, a small gap is formed between the piston 308 and the cylinder 301, preferably, the gap is 5-30 microns, more preferably 10 microns, which realizes the gas isolation of the cavity before and after the piston, and the efficiency can reach 80%. above. When the piston 308 is driven by the sound pressure generated by the thermoacoustic engine 200, the permanent magnet 306 will reciprocate in a straight line along the axial direction with the main shaft 304, and an alternating magnetic flux change will be generated on the plane of the coil 302, thereby creating a magnetic flux in the coil 302. 302 forms an induced electromotive force at both ends.

It can be seen from the above embodiments that in the embodiment of the present invention, the permanent magnet in the permanent magnet motor is driven by the self-excited oscillation sound pressure, thereby generating an induced electromotive force. Since the driving force for the motion of the permanent magnet is provided by the self-excited oscillation of the thermoacoustic engine, the thermoacoustic engine has no moving parts, so it has a high degree of reliability. The thermoacoustic system is a traveling wave type thermoacoustic system, so that the thermoacoustic conversion efficiency is high. The moving parts of the permanent magnet motor are in a normal temperature environment, and there is a small gap between the piston and the cylinder, so there is no failure caused by high temperature and wear, and the operating life is long. Moreover, the use of isotopes as heat sources can increase the service life of the heat source, and can realize long-term stable supply of heat energy under unattended conditions.

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

Claims (9)

1. A thermoacoustic generator, characterized in that it comprises an isotope heat source, a regenerator, a main cold end heat exchanger, an acoustic cavity, an acoustic feedback tube and a permanent magnet motor, and the permanent magnet motor comprises a permanent magnet and Surrounding the coil outside the permanent magnet, the regenerator, the main cold end heat exchanger, the acoustic cavity and the acoustic feedback tube are connected in sequence, the outlet end of the acoustic feedback tube is provided with a sound pressure output port, and the acoustic feedback tube is provided with a sound pressure output port. A cylinder with a piston is arranged between the pressure output port and the permanent magnet motor. The permanent magnet in the permanent magnet motor is connected with the piston in the cylinder. The isotope heat source and the main cold end heat exchanger make the regenerator A temperature gradient is formed at both ends, and a thermal-acoustic self-excited oscillation of heat energy to sound energy conversion is formed in the regenerator, thereby generating a self-excited oscillation sound pressure at the sound pressure output port, and the self-excited oscillation sound pressure drives the permanent magnet motor through the piston The permanent magnet in the reciprocating motion forms an induced potential in the coil. 2. The thermoacoustic generator according to claim 1, characterized in that the gap between the piston and the cylinder is 5-30 microns. 3. The thermoacoustic generator according to claim 1, wherein the heat provided by the isotope heat source is transferred to the hot end of the regenerator through the hot end heat exchanger, and the sound pressure output port is connected with a secondary cold end heat exchanger, the secondary cold end heat exchanger communicates with the hot end heat exchanger through a thermal buffer tube, the hot end heat exchanger, regenerator, main cold end heat exchanger, acoustic cavity, acoustic power The feedback pipe, the sound pressure output port, the heat exchanger at the sub-cooling end and the thermal buffer pipe form a closed loop loop. 4. The thermoacoustic generator according to claim 1, wherein the heat exchanger at the main cold end is an air-cooled or water-cooled heat exchanger. 5. The thermoacoustic generator according to claim 1 or 2, wherein the permanent magnet is connected to the piston through a main shaft, and the main shaft is fixedly connected to the plate spring in the permanent magnet motor, and the plate-shaped Spring to support the spindle. 6. The thermoacoustic generator according to any one of claims 1-3, wherein the isotope heat source is plutonium-238 or polonium-210. 7. The thermoacoustic generator according to any one of claims 1-3, characterized in that a thermal control device is provided on the isotope heat source for controlling the temperature generated by the isotope heat source. 8. The thermoacoustic generator according to any one of claims 1-3, wherein the casing of the permanent magnet motor is a closed casing. 9. The thermoacoustic generator according to any one of claims 1-3, characterized in that a wire mesh or plate stack is arranged in the regenerator.