A thermoacoustic oscillator powered by vaporized water and ethanol

We measure the temperature difference required to drive a thermoacoustic oscillator containing air, water vapor, and liquid water as the working fluids. The oscillator is composed of a large tube containing an array of narrow tubes connected at one end to a tank of liquid water. When the water is heated, the temperature difference across the tube array increases until thermoacoustic oscillations occur. The temperature difference at the onset of oscillation is measured to be 56 ° C , significantly smaller (by ∼ 200 ° C ) than the temperature measured when the tank is filled with dry air instead of water. The temperature difference can be further reduced to 47 ° C by using ethanol instead of water.