The influence of ambient pressure below atmospheric and heating rate on bubble dynamics associated with rapid evaporation in highly superheated water is investigated in this work. The average surface temperature of thin platinum strips immersed in water is shown to oscillate with a frequency on the order of 0.5 MHz. The oscillation frequency increases with ambient pressure in the range 0.002MPa and 0.101MPa. High speed imaging was used to show that the growth phase was associated with surface heating and the collapse phase with cooling in the cyclic temperature history. The nucleation temperature was unaffected by pressure in the sub-atmospheric range examined while it approached the theoretical limit for water at 109°C/s.
Citation: Journal of Heat Transfer-Transactions of the ASME
Pub Type: Journals
bubble, homogeneous nucleation, microheater, nucleation, vacuum