1 Development and Assessment of Two Stage 2 Thermoacoustic Electricity Generator 3
This paper presents the development and assessment of a two stage thermoacoustic 14 electricity generator that aims to mimic the conversion of waste heat from the internal combustion 15 engine exhaust gases into useful electricity. The one wavelength configuration consists of two 16 identical stages which allow coupling a linear alternator in a "push pull" mode because of the 180deg 17 out of phase acoustic excitation on two sides of the piston. This type of coupling is a possible solution 18 for the low acoustic impedance of the looped tube traveling wave thermoacoustic engines. The 19 experimental set up is 16.1 m long and runs at 54.7 Hz. The working medium is helium at maximum 20 pressure of 28 bar. In practice, the maximum generated electric power was 73.3 W at 5.64% thermal21 to electric efficiency. The working parameters: load resistance, mean pressure and heating power 22 were investigated. System debugging illustrates the effect of local acoustic impedance of the 23 regenerator on the start up process of the thermoacoustic engine. The additional modelling showed 24 that the feedback loop length can be reduced by using a combination of acoustic inertance and 25 compliance components. 26