Influence of a magnetic field on the energy, work, and heat flux of a multi-plate thermoacoustic system

Abstract

Research on clean and efficient energy conversion is extremely important to mitigate the high price of fossil fuel and its adverse effects on the environment. Thermoacoustic is a clean energy conversion technology that uses the conversion of acoustic to thermal energy and vice versa. However, the efficient conversion of acoustic to thermal energy using thermoacoustic systems (e.g., engine, refrigerator, or heat pump) demands research on working fluids, operational, and geometric parameters. The present study is a contribution to improve the efficiency of a thermoacoustic heat system by introducing a magnetic field perpendicular to the direction of the oscillating fluid. The major focus of this study is to examine the effect of a magnetic field on three important performance parameters: energy, heat, and work fluxes of a multi-plate thermoacoustic system. Initially, analytical expressions for the fluctuating velocity and temperature are derived from the governing continuity, momentum, and energy equations by applying the first order perturbation technique and solving these equations. The derived first order analytical equations for the fluctuating velocity and temperature enable us to calculate the energy, heat, and work fluxes and are expressed in terms of dimensionless Hartmann number (Haδ), temperature gradient ratio (Γ0), Swift number (Sw), Prandlt number (Pr), and modified Rott's and Swift's parameters (fv and fk). It is observed that the normalized energy flux density increases with increasing Haδ and Γ0 when Sw<1.5. The heat flux and work flux densities also increase with increasing Haδ and Γ0 when Sw<1.5 and decrease when Haδ>1.5. The findings of this research will provide useful information to thermoacoustic system's designers for the devloepment of effieicnt magnetic thermoacoustic heat pumps.