Design, construction and evaluation of a standing wave thermoacoustic prime mover

A standing wave thermoacoustic prime mover (TAPM) has been succesfully designed, constructed, and evaluated. It consists of a resonator with length of 128cm, a stainless-steel wire-mesh stack with 14 mesh number, two heat exchangers, and air at atmospheric pressure as the working gas inside the resonator. The stack is placed inside the resonator near one of its closed-ends and has 4cm length. The hot and ambient heat-exchangers are attached at each end of the stack to provide a large temperature gradient along the stack which is required for generating acoustic energy. An electric heater with maximum power of 400W is used to supply thermal energy to the TAPM. The temperatures and dynamic pressures are measured by using type-K thermocouples and pressure transducers, respectively. We evaluated the prime mover by experimentally investigating the influence of heat input power on the onset temperature difference, time to reach the onset condition, sound frequency, and sound pressure amplitude. It was found that input power below 255W could not generate sound, and its increase from 255W to 400W did not significantly change the onset temperature difference and sound frequency, namely of around 258 °C and 141Hz (at temperature difference ΔT across the stack of 300 °C), respectively. In addition, the increase of input power in the range of 225W-400W has raised the pressure amplitude from 3.3kPa up to 4.5kPa (within ΔT of 300 °C-320 °C). Moreover, we found that the time to reach onset condition was inversely proportional to the input power. We also checked the influence of temperature difference across the stack on the sound frequency and sound pressure amplitude. It was observed that the frequency was slightly increasing from 139Hz to 142Hz and pressure amplitude was getting higher from 1.4kPa to 5.1kPa when the temperature difference was rising from 280 °C to 350 °C, with input power of 353W.