Development of Thermoacoustic Arrays for Power.

Themoacoustic heat engines with piezoelectric devices provide a simple approach to converting heat to electricity. Heat generates sound in an acoustic resonator, which is converted to electricity. For high power, arrays of engines are used. The development of such approach deals with the coupling of engines for synchronization, frequency tuning of resonant components, stability, and performance. Standing wave thermoacoustic engines (2 to 6) at ~2.5 kHz were mounted on a cavity housing piezoelectric devices for converting sound to electricity, and the cavity provided coupling. Above a threshold temperature difference, oscillations were initiated, and they appeared synchronized. The engines were tuned to the piezos. Temperature changes led to detuning. This was compensated by using two piezos of different resonant frequencies, and each piezo was coupled to a Helmholtz resonator, making broadband response and maintaining sensitivity. The increase in power density in the above-coupled engines can be eventually applied to large systems, i.e. arrays.