Numerical investigation of a thermoacoustic engine core via heat transfer calculations coupled with acoustic field analyses

Abstract

Thermoacoustic engines are generating increased interest due to their potential use in renewable energy systems. The heat transfer characteristics of such engine cores were examined in this study via numerical simulations, taking into consideration the interactions between the acoustic field and thermal motion of fluids in a thermoacoustic device. Our calculations were based on the energy conservation equation under the assumption of a periodically steady oscillatory flow and thermoacoustic linear theory. The temperature field of the engine core was numerically solved by applying the finite difference method (FDM) to the energy equation, and also compared with CFD results. To systematically clarify the heat transfer characteristics of the oscillatory flow in the engine core, dimensional analyses for the associated geometries and physical values were performed, and nondimensional parameters were selected to determine the heat transfer characteristics. The simulation was performed using these nondimensional parameters, and the correlations of local Nusselt number distributions and some nondimensional parameters were considered. Based on the correlations among heat transfer characteristics, a model was constructed for predicting the temperature gap between the wall and the fluid at the edge of a regenerator. This model was satisfactory when the Reynolds number ranged from 30 to 120 and the nondimensional relaxation time was 0.3–1.3.