Design , Construction and Resonance Tracking of a Laboratory - Scale , Loudspeaker - Driven Thermoacoustic Cooler Autumn Term 2013

This thesis describes the design, construction and control of a quarter-wavelength, loudspeaker-driven thermoacoustic refrigerator. The stack and resonator design is based on linear thermoacoustic theory combined with numerical simulations in the thermoacoustic design software DeltaEC. The mechanical layout focuses on experimental flexibility and ease of maintenance, which leads to a modular system design. Despite using air at ambient pressure as working fluid, the presented thermoacoustic cooler reaches more than 20 degrees Celsius temperature difference across the stack. Based on an experimental system characterization, two different performance criteria and control goals are identified. For tracking the system’s acoustic resonance frequency, a novel, harmonics-based control strategy is proposed, which does not require measurement nor estimation of the speaker state.