The mechanism of thermal diffusion effect on thermacoustic mixture separation

In a resonator filled with binary mixtures, the oscillation of acoustic waves will create oscillating temperature gradient in the radial direction. The radial temperature gradient will lead to diffusion of the light and heavy components along the opposite directions. Based on the thermal diffusion effect and the thermoacoustic effect, the two components can be pumped to the velocity node and the pressure node respectively, which results in separation of the mixture along the propagation direction of sound wave. In order to study the mechanism of thermoacoustic mixture separation, a two-dimensional numerical model has been developed in a half-wavelength resonator. Then a numerical method based on the compressible SIMPLE algorithm is proposed to solve the velocity field, temperature field and the concentration field of a certain component. It is found that the numerical results are in good agreement with theoretical predictions from literature. Then the temperature, velocity, and concentration distributions of the mixture along the radial direction have been studied to investigate the thermal diffusion process and the mass and heat transfer process along the radial direction. This work provides insight into how the mixture can be separated along the wave-propagation direction.