Design of a thermoacoustic heat engine for low temperature waste heat recovery in food manufacturing

There is currently an urgent demand to reuse waste heat from industrial processes with approaches that require minimal investment and low cost of ownership. Thermoacoustic heat engines (TAHEs) are a kind of prime mover that convert thermal energy to acoustic energy, consisting of two heat exchangers and a stack of parallel plates, all enclosed in a cylindrical casing. This simple design and the absence of any moving mechanical parts make such devices suitable for a variety of heat recovery applications in industry. In this present work the application of a standing-wave TAHE to utilise waste heat from baking ovens in biscuit manufacturing is investigated. An iterative design methodology is employed to determine the design parameter values of the device that not only maximise acoustic power output and ultimately overall efficiency, but also utilise as much of the high volume waste heat as possible. At the core of the methodology employed is DeltaEC, a simulation software which calculates performance of thermoacoustic equipment. Our investigation has shown that even at such a comparatively low temperature of 150 °C it is possible to recover waste heat to deliver an output of 1029.10 W of acoustic power with a thermal engine efficiency of 5.42%.