Acoustics08, Paris, France
Low operating temperature integral thermo acoustic devices for solar cooling and waste heat recovery
Utilizing low temperature differences from solar vacuum tube collectors or waste heat in the range 70-200 °C seems to be the most promising field of applications for thermo acoustic systems.At these reduced temperatures overall system performance is increasingly affected by the ratio between amplified (useful) power and acoustic power in the resonance circuitry.Well known is that this ratio can be improved by deploying multiple regenerator units (hex-reg-hex).However, in commonly used torus or coaxial bypass configurations the correct timing (real and high acoustic impedance) is hardly to realize inside more than two regenerator units (soft spot).Acoustic losses in the standing wave resonator together with a high regenerator impedance account for another fundamental limitation because of the relatively low transferred and loop power at a given pressure amplitude.Therefore a novel acoustic geometry will be presented in which a near real impedance can be maintained in even more than two regenerator units and in which acoustic feedback is performed by a near traveling wave.This approach improves the overall performance of low operating temperature thermo acoustic systems.
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