RU2809514C1 - Method for supplying and removing heat in thermoacoustic engine and device for its implementation - Google Patents

Abstract

FIELD: thermoacoustic power generators.

SUBSTANCE: invention is related to thermoacoustic engines that convert thermal energy into energy of an acoustic wave and then into electricity. The invention can be used in rocket and space technology, solar energy and energy saving. The thermoacoustic engine works as follows. Heat is removed and supplied to the working fluid (gas) located inside the resonator 7 using a cold heat exchanger 1 and a hot heat exchanger 3. In regenerator 2, the necessary temperature distribution with the corresponding gradient is formed and the thermoacoustic effect of converting heat into wave energy is realized. Next, the kinetic energy of the oscillating gas on the impeller of the pulsation turbine 5 is converted into mechanical work and, with the help of an electric generator 6 located in the casing of the impeller of the turbine 6, into electricity. The guide apparatus of the pulsation turbine 4 performs the function of a secondary cold heat exchanger 8, that is, it removes the body in the thermoacoustic engine, preventing the resonator cavity from being heated by the hot heat exchanger 3. Moreover, heat removal can be carried out by both the input and output guide vanes of the pulsation turbine 4.

EFFECT: solution to these technical problems in the proposed invention will reduce the hydraulic and acoustic resistance in the circuit of the thermoacoustic engine, increase its thermodynamic efficiency by combining the functions of the heat exchanger and the guide vane of the pulsation turbine, and thereby simplify the design of the thermoacoustic engine.

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Description

The invention relates to thermoacoustic power generators, namely to thermoacoustic engines that convert thermal energy into the energy of an acoustic wave and then into electricity. The invention can be used in rocket and space technology, solar energy and energy saving.

A single-stage thermoacoustic engine with a traveling wave is known, including a resonator in the form of a looped pipe and a stage that amplifies acoustic vibrations, consisting of hot and cold heat exchangers and a regenerator between them (Ceperley P.H. A pistonless Stirling engine - the traveling wave heat engine // J Acoust Soc. Am. 1979. Vol. 66, No. 5. P. 1508-1513. DOI: https://doi.org 10.112/1.383505). As the temperature difference between the heat exchangers increases, the gain in the regenerator becomes greater than the attenuation when the wave passes through the remaining elements and the engine self-starts. This design has insufficient efficiency due to friction losses due to the high oscillatory velocity of the gas in the regenerator. In addition, in this engine, the presence of a phase difference between the pressure and gas velocity in the regenerator zone leads to additional losses.

There is a known method of noise suppression and a device for utilizing acoustic energy in exhaust systems of power plants (Patent RU 2626192, published on July 24, 2017). According to the method, based on the principle of reducing the level of acoustic power of an oscillating gas flow in the exhaust system, acoustic wave energy in the engine exhaust system or in the compressed gas exhaust line of a compressor is directed into specially organized acoustic paths containing at least one pulsation turbine, which , converting the acoustic energy of an oscillating gas flow into mechanical and then into electrical energy, selects part of the total acoustic energy from the gas in the exhaust system of the power plant, as a result of which the level of acoustic pressure in the exhaust pipeline of the power plant decreases and, thus, realizes a double positive effect: noise reduction and additional energy generation.

There is a known version of a four-stage thermoacoustic engine with a traveling wave, each stage of which includes cold and hot heat exchangers and a regenerator between them, a thermal buffer tube, a secondary cold heat exchanger, a load and a resonator (Gorshkov I.B., Petrov V.V. Numerical modeling of an annular four-stage thermoacoustic engine with a traveling wave // Izvestia Saratov University, Nov. Ser. Ser. Physics. 2018. T. 18, issue 4. P. 285-296. https://doi.org/10.18500/ 1817-3020-2018-18-4-285-296). A secondary cold heat exchanger is installed to prevent the resonator cavity from being heated by a hot heat exchanger, which can lead to increased losses. In thermoacoustic engines, a linear electric generator or an electric generator based on a pulsation turbine can be used as a load.

This four-stage thermoacoustic traveling wave engine and its method of operation are adopted as a prototype for the invention.

The disadvantage of the prototype is the complexity of the design and the increase in hydraulic resistance due to the installation of a secondary heat exchanger and the presence of load.

The technical problem to which the present invention is aimed is to increase the thermodynamic efficiency in a thermoacoustic engine by simplifying its design, reducing hydraulic and acoustic resistance in the thermoacoustic engine circuit.

A design solution that ensures the achievement of this technical task is to combine the functions of the heat exchanger and the guide vane of the pulsation turbine. Heat exchangers are structurally a set of plates. The guide vanes of a pulsation turbine are also sets of thin profiles (blades) with surfaces equidistantly located relative to each other. In this case, the guide apparatus of the pulsation turbine, based on the number of blades and their total surface, can be designed in such a way that, in addition to organizing the movement of the gas flow, it can provide the necessary supply or removal of heat, that is, perform the function of a heat exchanger.

The problem is solved due to the fact that in the proposed thermoacoustic engine containing cold and hot heat exchangers, a regenerator between them, a resonator, according to the invention, a pulsation turbine is installed behind the hot heat exchanger in the direction of propagation of the acoustic wave, with fixed blades of the input and output guide vanes of the pulsation the turbines are made integral with their casings, outside of which flow chambers are formed for supplying coolant to remove heat, and the casings of the guide vanes themselves and the impeller housing are made separately, and the electric generator is located in the turbine impeller casing.

In addition, the blades of the input and output guide vanes of the pulsation turbine are profiled in such a way that they perform the function of a pneumatic diode - suppressing circulating gas flows.

The essence of the proposed technical solutions is illustrated by drawings, where:

- in Fig. 1 shows a diagram of the proposed thermoacoustic engine;

- in Fig. 2 shows a design option where the guide vane of a pulsation turbine performs the function of a cold heat exchanger for heat removal in a thermoacoustic engine;

- in Fig. 3 shows a design option where the guide vane of a pulsation turbine performs the function of a hot heat exchanger for supplying heat to a thermoacoustic engine operating at negative temperature levels;

- in Fig. 4 shows a design option where the guide vane of a pulsation turbine acts as a hot heat exchanger for supplying heat to a thermoacoustic engine operating at positive temperature levels.

The thermoacoustic engine contains a cold heat exchanger 1, a regenerator 2, a hot heat exchanger 3, a pulsation turbine guide vane 4, a pulsation turbine impeller 5, an electric generator 6, and a resonator 7.

The thermoacoustic engine works as follows. Heat is removed or supplied to the working fluid (gas) located inside the resonator 7 using a cold heat exchanger 1 and a hot heat exchanger 3. In regenerator 2, the necessary temperature distribution with the corresponding gradient is formed and the thermoacoustic effect of converting heat into wave energy is realized. Next, the kinetic energy of the oscillating gas on the impeller of the pulsation turbine 5 is converted into mechanical work and, with the help of an electric generator 6 located in the stationary housing of the turbine 6, into electricity. In FIG. 1, the guide vane of the pulsation turbine 4 performs the function of a secondary cold heat exchanger 8, that is, it removes the body in the thermoacoustic engine in order to prevent the resonator cavity from being heated by the hot heat exchanger 3. Moreover, heat removal can be carried out by both the input and output guide vanes of the pulsation turbine 4.

In FIG. 2 shows a design option where the guide vane of the pulsation turbine 4 performs the function of a cold heat exchanger 1 to remove heat at the inlet of the regenerator in a thermoacoustic engine. That is, heat is supplied in the hot heat exchanger 3, and heat is removed by the blades of the output guide vane of the pulsation turbine 4. In the regenerator 2, the necessary temperature distribution and wave generation are formed.

In FIG. Figure 3 shows a design option where the guide vane of the pulsation turbine 4 performs the function of a “conditionally” hot heat exchanger 3 for supplying heat at the outlet of the regenerator in a thermoacoustic engine.

Since the performance of a pulsation turbine is objectively limited by the temperature level of the materials, it is desirable that the temperature level at the pulsation turbine does not exceed the permissible level. The fulfillment of permissible temperature conditions can occur, for example, when utilizing low-potential heat (cold) of a cryogenic liquid during its regasification to remove heat from a thermoacoustic engine and using external heat from the environment or another secondary body of industrial emissions to supply heat to a thermoacoustic engine, that is, in inlet guide vane of the pulsation turbine 4.

In FIG. 4 shows a design option where the guide vane of the pulsation turbine 4 performs the function of a hot heat exchanger 3 for supplying heat to a thermoacoustic engine operating at positive temperature levels. That is, in the cold heat exchanger 1 and the secondary cold heat exchanger 8, heat is removed, and the heat supply is provided by the input guide devices of the pulsation turbine 4 from the environment or other heat sources.

The solution to these technical problems in the proposed invention will reduce the hydraulic and acoustic resistance in the circuit of the thermoacoustic engine, increase its thermodynamic efficiency by combining the functions of the heat exchanger and the guide vane of the pulsation turbine, and thereby simplify the design of the thermoacoustic engine.

Claims (2)

1. A thermoacoustic engine containing cold and hot heat exchangers and a regenerator between them, a resonator, characterized in that a pulsation turbine is installed behind the hot heat exchanger in the direction of propagation of the acoustic wave, while the fixed blades of the input and output guide vanes of the pulsation turbine are made integral with their housings , outside of which flow chambers are formed for supplying coolant to remove heat, and the housings of the guide vanes and the impeller housing themselves are made separately, and the electric generator is located in the turbine impeller housing. 2. Thermoacoustic engine according to claim 2, characterized in that the blades of the input and output guide vanes of the pulsation turbine are profiled in such a way that they perform the function of a pneumatic diode - suppressing circulating gas flows.

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