Local and mean heat transfer coefficients in bubbly and slug flows under microgravity conditions

Slug to annular flow transition of microgravity two-phase flow

“…Fig. 2(a) plots the data of gas/liquid two-phase experiments with air/water mixture in a tube of 9.525 mm ID (Zhao andRezkallah, 1993, 1995;Rite and Rezkallah, 1997), while Fig. 2(b) plots the data of R12 vapor/liquid mixture in a tube of 10.5 mm ID (Reinarts, 1993).…”

“…Experiments: (a) air/water¯ow in a tube of 9.525 mm ID. * slug, w slug-annular, R annular (Zhao and Rezkallah, 1993); Q slug, q slug-annular, T annular (Zhao and Rezkallah, 1995); +slug, r slug-annular, Â annular (Rite and Rezkallah, 1997); (b) R12 vapor/liquid¯ow in a tube of 10.5 mm ID. * slug, w slug-annular, R annular (Reinarts, 1993).…”

“…bubble, slug and annular¯ow. Several experimental methods have been suggested to collect the data of¯ow patterns, for example, Reinarts (1993) used onecomponent vapor/liquid mixture and Zhao andRezkallah (1993, 1995), Bousman (1995), and Rite and Rezkallah (1997) used two-component gas/liquid mixtures on board parabolic¯ight of airplane, while Lovell (1988) used equi-density, immiscible liquid/liquid systems and Mishima and Hibiki (1996) used miniscale capillary tubes on the ground. Models of¯ow International Journal of Multiphase Flow 26 (2000) 1295±1304 0301-9322/00/$ -see front matter 7 2000 Elsevier Science Ltd. All rights reserved.…”

Numerical Investigation on Turbulence and Bubbles Distribution in Bubbly Flow Under Normal Gravity and Microgravity Conditions

“…As a result, twophase bubbly flows are extensively applied to routine industrial processes such as oil wells, boilers, nuclear reactors, and airlift pumps due to its high efficiency in heat and mass transfer (Cédric et al 2009). With the development of space-based systems such as satellites for communications and research purposes, technologies of two-phase flows have increasingly been paid much attention to space applications to meet demands of high thermal transport (Rite and Rezkallah 1997). Two-phase gas-liquid thermal control system has also been considered as a better alternative to single phase pumped liquid loop to meet the growing power demand for spacecraft thermal management (Bhunia and Kamotani 2001).…”

“…The bubble and liquid turbulence characteristics of air-water bubbly flow in a large diameter vertical pipe were experimentally investigated by Shawkat et al (2008). Different from the above researches, Rite and Rezkallah (1997) reported local and mean heat transfer coefficients in bubbly flows under microgravity condition, and Chahed et al (2002) investigated turbulence and phase distribution in bubbly pipe flow under microgravity condition using a Eulerian-Eulerian two-fluid model. The turbulent stress tensor of the gas is related to that of the liquid through a turbulent dispersion model and the turbulent stress tensor of the liquid is computed using a secondorder closure of turbulence (Chahed et al 2002).…”