A traveling-wave thermoacoustic electric generator with a variable electric R-C load

Abstract

A traveling-wave thermoacoustic electric generator, which is composed of a traveling wave thermoacoustic engine and linear alternators, is promising in solar power generation and energy recovery due to its high efficiency, high reliability, and capability of utilizing low-grade heat. An equivalent acoustic circuit of a linear alternator is first built and analyzed using electro-mechano-acoustical analogy. It is found that the acoustic coupling of the linear alternators to the traveling-wave thermoacoustic engine is crucial to the performance of the system. A traveling-wave thermoacoustic electric generator with a variable electric R-C load is then constructed and experimentally studied. Both the theoretical analysis and the experimental results show the importance of mechanical and electrical resonances to the overall performance of the system. Furthermore, the thermal-to-electric efficiency and the electric power are found to be proportional to the pressure amplitude and the square of it in front of the piston of the linear alternator, respectively. By optimizing the load impedance, the traveling-wave thermoacoustic electric generator has achieved a maximum electric power of 345.3 W with a thermal-to-electric efficiency of 9.34% and a maximum efficiency of 12.33% with an electric power of 321.8 W at around 65 Hz when helium of 3.0 MPa is used as the working gas.

Numerical simulation on onset characteristics of traveling-wave thermoacoustic engines based on a time-domain network model

“…The energy conversion process in a traveling-wave thermoacoustic engine takes place reversibly based on a good thermal contact between gas and porous solids in the regenerator. As a result, traveling-wave thermoacoustic engines work more efficiently and are more promising in the practical applications compared to their standing-wave counterparts [12,15].…”

Study of Standing-Wave Thermoacoustic Electricity Generators for Low-Power Applications

“…The performance also increases when the electrical reactance (X e ) is decreased. An additional condenser could be added to the coil circuit to use the alternator in favorable electrical resonant conditions (X e = 0) at the selected operation frequency [9] (even if the inductance of the voice coil, ωL e , is generally negligible at the typical working frequencies of TA devices for standard woofers and sub-woofers). Finally, the amount of acoustic power absorbed by the alternator also grows with decreasing mechanical reactance X m so the performance of the device is highest when it works in both mechanical and electrical resonant conditions (X m = 0, X e = 0) for which the alternator acoustical impedance becomes real (p 1 − p 2 in phase with U).…”

A two-stage traveling-wave thermoacoustic electric generator with loudspeakers as alternators

“…A thermoacoustic generator combines the advantages of a thermoacoustic engine and a linear alternator to generate electricity from low temperature heat sources with high efficiency and high reliability. There have been continuous research efforts to develop travelling-wave thermoacoustic electric generator in the past decade [11][12][13][14][15][16][17]. However, the linear alternators are costly, which counteracts the advantages of thermoacoustic engines such as simplicity and low cost.…”