Investigation on a 1 kW traveling-wave thermoacoustic electrical generator

Abstract

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 1kW 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 638W 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 74Hz to 64Hz by charging 4.5% mole fraction argon gas into the system. And a maximum electric power of 1043W 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 970W were obtained successfully. Other operating conditions were a mean pressure of 4.0MPa, 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.