Theoretical And Experimental Study Of A Stirling Thermoacoustic Engine

Thermoacoustic engines convert heat into mechanical work in the form of pressure oscillation. With no moving parts, it has the merit of simple configuration and long-life stabilization, which makes it promising and distinct from traditional compressors or heat engines.The history of thermoacoustics is reviewed, followed by brief introduction of theory of linear thermoacoustics. Streaming in thermoacoustics is mainly discussed, in terms of causation, category, suppression methods and deliberate uses.This thesis is primarily concerned with streaming in Stirling thermoacoustic engine. By introducing feedback path, Stirling thermoacoustic engine with toroidal configuration achieves relatively high efficiency in thermoacoustic conversion. However, the toroidal topology allows streaming acoustically induced, which can seriously degrade the performance of the engine. Based on measurements of pressure oscillation and temperature distribution, the relations among streaming, temperature distributions, pressure ratio, thermoacoustic conversion efficiency and acoustic work of the engine were investigated. It is shown that pressure ratio and acoustic work output were remarkably increased by sufficient suppression of streaming. With no acoustic load, the pressure ratio increased to 1.2, when the hot heat exchanger was heated at 517 ℃. When the input of heating power was 2700 W, the maximum output of acoustic power reached nearly 200 W, approximately 100% of rise, corresponding to proximately 90% of rise in exergy efficiency. Besides, a simplified enthalpy model was established in order to quantify the strength of streaming. The investigations are of importance for further understanding streaming in Stirling thermoacoustic engines.Because a thermoacoustic engine functions as an acoustic work generator, its acoustic work output is of most interest. Based on well understanding of streaming, this thesis studied acoustic work production of the engine. The variations of acoustic work output due to different acoustic loads, new acoustic transmission devices and...