A pistonless Stirling engine—The traveling wave heat engine

TLDR

Acoustic waves propagating through a differentially heated regenerator cause gas to undergo a Stirling thermodynamic cycle, with one direction amplifying waves to convert thermal energy into acoustical energy and the opposite direction using acoustical energy to pump heat; practical engines and heat pumps based on this principle are discussed. The study seeks to derive the ideal gain and maximum energy conversion rates for a pistonless Stirling engine. The authors analytically derive these rates from the wave propagation model in the regenerator. Experimental low‑power gain measurements confirm the derived gain equation.

Abstract

The propagation of acoustical waves through a differentially heated regenerator results in gas in the regenerator undergoing a Stirling thermodynamic cycle. One direction of wave propagation results in amplification of the waves and conversion of thermal energy into acoustical energy. The opposite direction results in acoustical energy being used to pump heat. The ideal gain and maximum energy conversion rates are derived in this paper. Low power gain measurements were made which verify the derived gain equation. Practical engines and heat pumps using this principle are discussed.