International Journal of Energy Research, Vol.44, No.3, 2298-2305, 2020
An electret-based thermoacoustic-electrostatic power generator
This study reports a new concept for power generation from thermal energy, which integrates a thermoacoustic engine (TAE) with a contact-free electret-based electrostatic transducer. The TAE converts thermal energy into high-intensity acoustic energy, while the electret-based electrostatic transducer converts the generated acoustic energy into electricity. The experiments demonstrate the feasibility and potential of the proposed electret-based thermoacoustic-electrostatic power generator (TAEPG). The dynamic response of the electrostatic transducer and energy conversion inside the TAE are further investigated using a lumped element model and a frequency-domain reduced-order network model. Good agreement is achieved between experimental measurements and theoretical predictions. Furthermore, a parametric study is performed to study the effect of key parameters including the external heating power, air gap, and resistive load on the performance of the TAEPG. Results show that an open-circuit voltage amplitude of 4.7 V is produced at a closed-end pressure amplitude of 480 Pa in the experiment, and it is estimated that 25.2% of the acoustic power generated by the TAE has been extracted by the electret-based electrostatic transducer. In this case, the maximum electric power output is measured to be 2.91 mu W at a resistive load of around 2.2 M omega. By increasing the external heating power, the TAEPG can produce a maximum voltage amplitude of 8 V. This work shows that the proposed concept has great potential for developing miniature heat-driven power generators.