Nonlinear effects in a model of a thermoacoustic refrigerator driven by a loudspeaker

It is known that acoustic nonlinear effects in thermoacoustic refrigerators are unfavorable to the performance because they transfer the acoustic energy of the fundamental wave to harmonic waves, while only the former is useful for refrigeration. To study the nonlinear effects in loudspeaker-drive thermoacoustic refrigerators, we measure the acoustic performance in a coupling system composed of a resonant pipe driven by an electrodynamic loudspeaker via an inverse horn. It is found that the nonlinear effects increase both the acoustic pressure of fundamental wave in the resonant pipe and the electroacoustic transfer efficiency of the system. Then, a theoretical model is established to study the nonlinear effects in the coupling system, in which the nonlinearities arising from the loudspeaker, inverse horn, and resonant pipe are taken into account, and the simulated results are used to explain the experimental phenomena.