Investigation on a 1 kW traveling-wave thermoacoustic electrical generator

• A prototype of 1 kW traveling-wave thermoacoustic electrical generator was presented.
• Maximum electrical power of 1043 W with 17.7% efficiency was achieved.
• Maximum thermal-to-electrical efficiency of 19.8% with 970 W electric power was obtained.
• Impedance coupling rule between the engine and the alternator was first revealed.
• System efficiency problem was discussed to provide clues for further improvement.

Traveling-wave thermoacoustic heat engine is a special device capable of converting external heat to acoustic work with high reliability and high potential efficiency. By coupling with a linear alternator, it can be further developed as a new kind of electricity generator called the traveling-wave thermoacoustic electrical generator. In this paper, a prototype of 1 kW traveling-wave thermoacoustic electrical generator was designed and tested. In the preliminary experiments, due to the high clearance seal loss caused by the pistons of the alternator, only 638 W electric power with 16.6% thermal-to-electrical efficiency was obtained, which was far below our expectation. After further investigation, the acoustic impedance coupling relationship between the engine and alternator was first revealed by means of numerical approach. According to this relationship, the working frequency was decreased in the experiments from 74 Hz to 64 Hz by charging 4.5% mole fraction argon gas into the system. And a maximum electric power of 1043 W with a thermal-to-electrical efficiency of 17.7% and a maximum thermal-to-electrical efficiency of 19.8% with an electric power were of 970 W were obtained successfully. Other operating conditions were a mean pressure of 4.0 MPa, a heating temperature of 650 °C and a cooling temperature of 15 °C. So far, the output electric power and efficiency are the highest values for such a thermoacoustic electrical generator. This work presents a new kind of thermal electric power generator, which is believed to be suitable for many applications in the energy area, such as solar energy, industrial waste heat and so on.