Design and thermodynamic analysis of a standing wave thermoacoustic superheater

The main objective here is to introduce and analyze a novel design to provide heat at higher temperatures, via a thermoacoustic super-heater, supplied by industrial wasted heat. The system includes two standing wave thermoacoustic engines with a symmetric configuration inside a resonator tube, with a constant linear temperature distribution (500-300 K) on stack plates. A high-temperature heat exchanger (HTHX) is placed in the middle of the resonator tube to extract heat at very high temperatures. This system is numerically simulated in which all non-linear terms are preserved. Two configurations were studied, the first includes an insulated HTHX which reached a high temperature of 800 K, while the HTHX in the second configuration was set to a constant high temperature of 700 K, to achieve a quasi-steady-state high temperature heat transfer. To understand the physics, a Lagrangian viewpoint was used for detail analysis of the aero-thermodynamic cycles of ten particles in the resonator region. It was shown that the engines produce mechanical energy from the wasted heat source, and it is transferred by micro-thermo-acoustic-engines in the resonator towards the system's middle region, to be dissipated there to produce heat at high temperatures. Detail analysis is presented to show how non-linear pressure waves asymmetrize the thermodynamic cycle to make each particle inside the resonator as a microthermoacoustic engine to mitigate heat conduction back towards the engines. The new insight and understanding provided here help designers to improve the performance of real non-linear standing wave engines, and achieve the industrial application of thermo-acoustic super-heating.