Theoretical modeling of forced convection condensation of steam in a vertical tube in the presence of a noncondensable gas

Journal Article · Sun May 01 00:00:00 EDT 1994 · Nuclear Technology; (United States)

OSTI ID:7237063

Siddique, M; Golay, M W; Kazimi, M S ^[1]

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1. Massachusetts Inst. of Tech., Cambridge, MA (United States). Nuclear Engineering Dept.

An analytical study was conducted to characterized the local condensation heat transfer coefficient of a vapor in the presence of a noncondensable gas, where the gas mixture is flowing downward inside a vertical tube. The two-phase heat transfer was analyzed using an annular flow pattern with a liquid film at the tube wall and a turbulent gas/vapor core. The liquid phase heat transfer was modeled as heat conduction across a falling film. The gas/vapor core was modeled using the analogy between heat and mass transfer. Emphasis was placed on including the effects of developing flow, condensate film roughness, and property variation in the gas phase. The prediction of the model were compared to the experimentally obtained data and reasonably good agreement was found. The results obtained show that for the same mass fraction of noncondensable gas, compared with air, hydrogen and helium have a more inhibiting effect on the heat transfer in that order, but for the same molar ration, (a) air was found to be more inhibiting, and (b) the heat transfer characteristics of hydrogen/steam and helium/steam mixtures are nearly identical. The results also show that the effects of developing flow are negligible when the inlet flow is at high turbulent Reynolds numbers (Re > 10,000). Also, the results show that the film roughness effects are negligible for gas mixtures with low Schmidt numbers (Sc < 1.0).

• OSTI ID: 7237063
• Journal Information: Nuclear Technology; (United States), Vol. 106:2; ISSN 0029-5450
• Country of Publication: United States
• Language: English

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