Influence of local inner diameter changes on the onset temperature and the energy conversion efficiency of a loop-tube-type thermoacoustic system

Abstract

The practical application of thermoacoustic systems requires a low onset temperature and improved energy conversion efficiency. To solve these problems, we study a phase adjuster (PA), which locally reduces the inner diameter of the tube and an expanding phase adjuster (EPA), which locally increases the inner diameter. We expect that the energy loss that depends on particle velocity will increase inside a PA with inner diameter smaller than that of the EPA. We evaluated the onset temperature and the energy conversion efficiency of systems with a PA or an EPA installed. The experimental results show that although the onset temperatures for both systems have low values, the energy conversion efficiency is better for the EPA system than for the PA one. This is suggest that the loss at a local part whose inner diameter is changed must be decreased to improve the energy conversion efficiency of a thermoacoustic system.