Analytical comparison of condensing flows inside tubes under earth-gravity and space environments
Abstract
The heat transfer behavior of flow condensation inside horizontal tubes under conditions of zero gravity and earth gravity is modeled and analyzed. For earth conditions for wetting fluids, the annular flow region changes to a stratified flow pattern as a result of gravity drainage of the condensate from the upper portion of the tube. The stratified condensate layer is considered inactive in the heat transfer process; its magnitude is determined along the tube length from the analytical results of Rufer and Kezios (1966). Under zero-gravity conditions, where no such gravity drainage is observed, the flow is considered to be annular along the complete length of the tube. The analytical approach of Bae (1970) is used to evaluate the heat transfer rates under zero-gravity conditions. The results suggest a substantially poorer condensing performance under zero-gravity conditions. It is pointed out that these results can be simply explained in terms of the smaller condensate film thickness over the upper portion of the tube periphery at any axial location under earth-gravity conditions because of gravity drainage of the condensate.
- Publication:
-
Rome International Astronautical Federation Congress
- Pub Date:
- September 1981
- Bibcode:
- 1981rome.iafcS....K
- Keywords:
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- Film Thickness;
- Gravitational Effects;
- Heat Transfer;
- Pipe Flow;
- Space Environment Simulation;
- Weightlessness;
- Annular Flow;
- Flow Characteristics;
- Flow Distribution;
- Flow Geometry;
- Flow Velocity;
- Space Commercialization;
- Stratified Flow;
- Fluid Mechanics and Heat Transfer