Bubble dynamics during degassing of liquids at microgravity conditions

Bubble dynamics during the non-isothermal degassing of liquids. Exploiting microgravity conditions

“…The problem is rather prototype and has not been studied in literature perhaps due to the serious disturbances created by gravity. To get the right picture, it is important to review first the main features of the experimental growth curves as observed under microgravity conditions [24][25][26]. In all examined fluids, bubbles grow fast at the beginning and gradually slow down at later stages.…”

“…The experimental set up has been described in detail by Divinis et al [24,25]. Here the major components are briefly presented.…”

“…Based on experimental observations of Karapantsios and co-workers [24][25][26] and on literature data of contact angle on glass, a slowly growing bubble can be assumed to be of a spherical shape having a point contact (zero contact angle) with the heater (a glass-coated thermistor, see Section 3). The complete physical problem includes: a) Transient heat conduction equation with a non-linear heat source (temperature-dependent ohmic resistance) in the heater.…”

“…In a series of ESA (European Space Agency) Parabolic Flight Campaigns, Karapantsios and co-workers [24][25][26] exploited the low-g conditions achieved during the free-fall of an airplane to study the slower (compared to boiling) bubble dynamics during degassing of several liquids. Bubble production was triggered by heat pulses given to a miniature submerged heater which raised the liquid temperature locally creating supersaturation of dissolved gas over the surface of the heater.…”

The Peristaltic Motion inside a Vertical Cylindrical Tube Surrounded Vapour Bubble with Two-Phase Density Flow

“…Thermal degassing which involves mass transfer but also heat transfer is thus achieved (as opposed to decompression degassing which only involves mass transfer in theory). To study the bubble generation and growth separately from the gravitational effects on them, the experiments where performed in microgravity conditions [5,6]. The experimental observations were compared to a theoretical model [7] derived considering spherical bubbles in a uniformly cooled liquid that were heated from the inside.…”