Nonlinear effects in thermoacoustic refrigerators driven by voltage-excited loudspeakers

A nonlinear model of electrodynamic loudspeakers excited by voltages is used to study the influences of nonlinearities of loudspeakers on performances of thermoacoustic refrigerators. The theoretical simulated results demonstrate that the nonlinearities of the magnetic fields and vibration components of the loudspeakers change electroacoustic transfer efficiencies and acoustic output powers of the loudspeakers, and the nonlinearities of the vibration components also shift the resonance frequencies of the loudspeakers. In the voltage-excited systems, the product of the magnetic induction intensity and the length of the coil play an important part in the performances of the acoustic source because of the influence of the motional electromotive force exerted on the coil when it is moving in the magnetic field. (c) 2008 American Institute of Physics.