Operation map of a traveling-wave thermoacoustic electric generator with variable resistive-capacitive electric loads.

A toroidal-topology traveling-wave thermoacoustic electric generator (TWTEG) is developed. It consists of a traveling-wave thermoacoustic engine, two linear alternators connected in parallel, and sets of variable resistive-capacitive (R-C) external electric loads, in conjunction with accessories and instrumentation required for experimental investigations. The working medium is helium with a static absolute pressure that varies from 25 bars to 30 bars. A detailed description of the thermal design of the heat exchangers is presented. Sustainable operation of the TWTEG is achieved over a range of external R-C loads at different imposed hot-side temperatures and mean gas pressures. The performance parameters are measured for different experimental conditions and compared with a developed lumped-element model. The comparison between the experimental results and predictions reveals a good agreement. The impedance matching between the thermoacoustic engine and the linear alternators is investigated experimentally over a wide range of external R-C loads. The external R-C loads play a crucial role in the operation of the TWTEG. The mean gas pressure changes the operating frequency; however, it has no significant influence on the operating range of the TWTEG on the R-C load map. Increasing the hot-side temperature improves the thermal-to-acoustic efficiency and extends the operating region into larger regions.