Shehua Thor

Heat is a form of energy that is treated as a byproduct of many processes. This wasted heat energy can be recovered to produce useful electrical energy. Direct conversion from thermal energy to electrical energy via thermoelectric materials is relatively inefficient and too expensive for the amount of energy it recovers. Thermoacoustics offers a cheaper alternative to indirectly convert thermal energy into electrical energy. This study presents the characteristics of three different sized standing wave thermoacoustic engines. These engines are used as a proof of concept for a novel thermoacoustic engine energy harvester. A steep temperature gradient across all the engines’ stacks were created by heating one end of the stack with a NiCr heating element and cooling the other end with water. After creating the temperature gradient, there was a time delay where the engine did not produce any sound. After this delay, each engine produced a sound of ~90dB at different frequencies. The largest engine produced a 440Hz sound, the medium engine produced a 589Hz sound, and the smallest engine produced a 885Hz sound. Attempts to measure the air temperature inside the engines with a thermocouple were unsuccessful; the thermocouples were not sensitive enough to observe these temperatures. These results suggest that smaller length engines produce higher frequency sounds and will probably be more efficient for energy harvesting when used with a piezoelectric transducer. Further studies will be needed to design and optimize the novel thermoacoustic engine energy harvester.