Wire mesh stack and regenerator model for thermoacoustic devices

Thermoacoustic technology can play a significant role in the development of renewable energies. Thermoacoustic engines and heat pumps (or refrigerators) are however characterized by a low efficiency attributed to suboptimal components. The core of these devices is a porous material, named stack (or regenerator), in which thermoacoustic conversion takes place. The most frequently used stack in the literature remains the wire mesh, although there is still a lack of formulation for the corresponding thermoviscous response functions. Essentially, all the dynamic thermal and viscous behaviors of a porous structure can be derived thanks to the Johnson-Champoux-Allard-Lafarge (JCAL) semi-phenomenological model, where transport parameters provide input information on the macroscopic level to the model. Here, we report a set of structure–property correlations between the transport parameters of the stack and the geometrical features of the wire mesh obtained from first-principles calculations. Validation of the model is carried out by means of experimental measurements performed on three different specimens. Our results show that the knowledge of the termoviscous functions for the wire mesh allows drawing preliminary considerations on the thermoacoustic efficiency of the stack, without needing to consider a full numerical simulation of the entire device.