Thermoacoustic engine working principle

      

  From the acoustic point of view, it comprised a closed-ended ‘bounce volume’, a hot-end heat exchanger, a thermoacoustic stack, and a cold-end heat exchanger, terminating in a flange onto which the linear alternator would have been bolted, all enclosed in a duct of approximately constant cross-section. The bounce volume was necessary to allow useful magnitudes of acoustic velocity in the stack, but it also provided the radiant surface for transmission to the hot-end heatexchanger. The overall length of the duct was short compared with the acoustic wavelengths to be generated because their frequency was determined by the resonant frequency of the alternator.