Multiphase Science and Technology A Quarterly

ISSN for PRINT: 0276-1459

For Online Access

Best Paper Award Selection - Editorial Board Site

2001, Volume13

Issue 1&2

182 pages

Issue price - $280.00

R. W. Rite
Research and Development Division, TRANE Co., Wisconsin, USA

K. S. Rezkallah
Microgravify Research Group, College of Engineering, University of Saskatchewan, Saskatoon, Canada

Experimental heat transfer data collected on-board NASA’s КС-135 reduced gravity aircraft for two-phase, two-component flows in vertical, upward, co-current flow through a 9.53 mm circular tube are reported and analyzed. Data were collected for water-air flow as well as for three glycerol/water and air mixtures. It was found that for low liquid flow rates reduced gravity retards the heat transfer coefficient by up to 50% at the lowest gas qualities (bubbly and slug flow regimes). As the gas quality is increased (transition to annular flow), the difference between the 1-G and m-G heat transfer coefficients becomes smaller. At higher liquid velocities, an increase in the gas quality results in the m-G heat transfer coefficients being greater than those at 1-G by approximately 10%, which is within the uncertainty of the measurements. The influence of gravity was found to be both a single-phase effect and a two-phase effect. Mixed convection in the liquid phase affects the heat transfer coefficients, and reduced gravity has a substantial influence on the interfacial surface between the two phases. New correlations for two-phase heat transfer have been developed. These correlations include the effect of flow regime and gravity on the two phases by incorporating the non-dimensional groups of Weber, Froude, and Morton numbers. From microgravity and 1-G data, the correlations developed were found to have an uncertainty of, at most, 25% for Re_ST < 2300, and 15% for higher liquid superficial Reynolds numbers.

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