Gedeon streaming suppression in a small scale thermoacoustic-Stirling engine-generator

Abstract

Thermoacoustic-Stirling engines, or traveling wave engines, have been shown to convert heat to acoustic power very efficiently (over 30% first-law) in the laboratory. The laboratory prototypes are generally heated from the inside by an embedded electric heater, have a long, bulky resonator, and deliver their work to an acoustic load rather than as electricity, leaving significant challenges required for commercialization unaddressed. The authors are part of a team developing a compact acoustic Stirling engine that is externally heated and is coupled to a pair of linear alternators, dubbed the Thermoacoustic-Stirling Engine-Generator (TaSEG). An important part of this work has been developing a commercially viable means of suppressing Gedeon streaming, a steady flow that circulates in an acoustic engine's toroidal geometry. In the laboratory, this streaming is typically suppressed by either a latex barrier or a “jet pump,'' a special flow element with asymmetric flow resistance, adjusted from the outside of the engine via a rod that passes through the pressure vessel. This work describes the design and testing of a simple, compact, and inexpensive element with multiple jet-pump orifices (the “jet plate''), which can replace the laboratory versions in a commercial engine.