Thermoacoustic nanotechnology: Derivation of a lower limit to the minimum reachable size

Abstract

A physical limit to the minimum reachable size of a thermoacoustic engine has been obtained. It aims for a better physical understanding of the influence of the gas behavior in the energy dissipation of such smallest devices, and it is based on physical considerations about pipes of large aspect ratios. The solution depends on the gas properties and on the main aspect ratio of the pipes configuring the engine. The expressions obtained may be used by designers to establish the expected frontier to the minimum size for a given working gas at a given thermodynamic condition inside a pipe of a given aspect ratio. Numerical values for several common gases used by actual engines are presented and the results are discussed. © 2007 American Institute of Physics.