Thermoacoustic energy conversion is based on the Stirling cycle. But rather than using pistons to create mechanical work, it utilizes sound waves. The most basic design of a thermoacoustic engine utilizes a simple resonance tube in which a regenerative unit (the stack) is placed. When the stack is subject to a temperature gradient, minute pressure disturbance in the resonator can be amplified to yield an intense sound wave as output. This amplification of the sound waves is the equivalent of mechanical work. Currently, this technology is limited by low energetic efficiency and the size of commercially available devices. The design of such devices is largely based on the hydraulic properties of the driving components. However, as the operation of thermoacoustic devices is based on the presence of temperature gradients across solids, thermal properties must be considered in the design phase. To date, this topic is underrepresented in the literature. This work will illustrate the influence of the thermal properties of the stack material on the thermoacoustic effect. The design of a thermoacoustic test setup is discussed. Measurements were conducted on stacks assembled with five feasible material choices, ranging from ceramic, with very low thermal conductivity, to copper, with high thermal conductivity. Results from the investigation highlight implications for device design and their miniaturization. In addition, the heat losses to the surroundings are estimated using data taken from the experiments. It is concluded that the thermal properties of the thermoacoustic stack are important design criteria and should be considered in future device designs.

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