New method to analyse and optimise thermoacoustic power generators for the recovery of residual energy

Abstract

The analysis of thermoacoustic engines and the equations that describe the internal physical phenomena are far from simple. Previous studies on energetic characterisation of thermoacoustic engines are based only on the determination of the active acoustic power flow distribution. In this paper, another variable, known as the reactive acoustic power, is additionally estimated and studied. This article proposes a simple method which is based on the combination of both active and reactive acoustic power flow for the evaluation and optimisation of thermoacoustic Stirling engines. In addition the paper illustrates the method using a thermoacoustic Stirling engine demonstrator design which is able to fit three different feedback branches. The results show that the amount of reactive acoustic power supplied towards the core branch differs depending on the specifications of the selected feedback branch. Besides, the amount of reactive acoustic power distributed towards the core branch is a good indicator of the grade of traveling-wave phasing. An improvement of 16.4% in the active acoustic power towards the extraction branch is achieved and besides, the amplification of the active acoustic power through the core branch has increased by 12%. The method can serve as an effective tool to study and optimise thermoacoustic devices.