Acoustic field improvement through adjustable resonator to enhance the performance of thermoacoustic-Stirling engine

In this study, the simulation and experiment of a thermoacoustic Stirling heat engine (TASHE) with a phase-adjuster are demonstrated. The phase-adjuster is used as a tool to tune the acoustic field of the TASHE in order to maintain the high performance of the system. The core components of the TASHE comprising an ambient heat exchanger, regenerator, hot heat exchanger, and feedback pipe, are located in the torus section. Besides, there is a resonator pipe, connecting to the torus, which acts as compliance to maintain the system stability, and the phase-adjuster is installed at the end of the resonator. Firstly, the TASHE is modeled by DeltaEC to search for the optimal configurations of the prototype. Due to the variations of acoustic load or operating conditions from the design criteria, the engine absolutely cannot provide maximum output power. The proposed phase-adjuster could keep its high efficiency by re-matching the frequency. In the experiments, the self-excited and steady-state temperatures of the TASHE are around 755 K and 670 K, respectively. Here, this TASHE can provide an acoustic power of up to 40 W, and an energy conversion efficiency of 12.03%. In comparison, there is a reasonably good agreement between the measured and DeltaEC simulated results. This can reflect on the preciseness of the proposed model. In the case of the TASHE operated under the off-design condition, these scenarios certainly drop its efficiency. Consequently, the role of the phase-adjuster in improving its performance by tuning the acoustic field is presented here. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).