Heat transfer coefficients during two-phase, gas-liquid flow in a circular tube under microgravity conditions
Abstract
A two-phase, two-component flow test loop was flown on-board NASA's KC-135 zero-g aircraft in October 1992. During the flights, flow regime, pressure gradient, and heat transfer data were simultaneously gathered for a water-air mixture in vertical, co-current, upward flow through a circular tube with a diameter of 9.53 mm. The range of flow rates studied consisted of superficial liquid velocities from 0.1 to 3.0 m/s and superficial gas velocities between 0.2 and 17 m/s. Heat transfer measurements taken during micro-g were compared with heat transfer data gathered at 1-g with the same test loop. This comparison indicated that at low liquid and gas velocities heat transfer coefficients at 1-g were up to 20 percent greater than those measured in micro-g. At higher liquid or gas velocities, this trend was reversed, and microgravity flows yielded heat transfer coefficients approximately 10 percent higher than the corresponding 1-g flows. The greatest difference in heat transfer between the two gravity levels occurred during slug and annular flows at micro-g, where churn-type flows existed at 1-g. However, it was found that a change in the flow regime was not totally responsible for this difference in heat transfer coefficients.
- Publication:
-
AIAA, 28th Thermophysics Conference
- Pub Date:
- July 1993
- Bibcode:
- 1993thph.confS....R
- Keywords:
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- Flow Velocity;
- Heat Transfer Coefficients;
- Microgravity;
- Two Phase Flow;
- Annular Flow;
- Flow Distribution;
- Gravitational Effects;
- Phase Transformations;
- Fluid Mechanics and Heat Transfer