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ABSTRACT
Governing the rate of heat transport by condenser tubes in the passive containment cooling system (PCCS), the steam condensation over a vertical cylinder in the presence of air was investigated experimentally. The main objective of this study was to explore if the condensation heat transfer coefficient relies on the tube dimension, which has been a variable missed in most condensation models or has been embraced without experimental demonstration under phase change environments. The mean heat transfer coefficient was measured in the condensation test facility named JERICHO (JNU Experimental Rig for Investigation of Condensation Heat transfer On tube). The outer diameter of the condenser tube used in this study was set to 21.5 mm. The measured heat transfer coefficients were compared to those obtained from the 40-mm-O.D. tube, and a multiplier to correct the variation of the heat transfer coefficient with the tube diameter was proposed for its application to Lee correlation. The proposed correlation was further validated against another set of experimental data obtained from a separate test facility housing the 31.8-mm-O.D. tube.
Acknowledgments
The authors are deeply grateful to Dr. Sang Gyu Lim of KHNP Central Research Institute for sharing valuable experimental data from ATRON. This work was supported by the Nuclear Power Core Technology Development Program of the Korea Institute of Energy Technology Evaluation (KETEP) granted financial resources by the Ministry of Trade, Industry and Energy, Republic of Korea [number 20161510400120].
Disclosure statement
No potential conflict of interest was reported by the authors.
Nomenclature
| As | = | Surface area (m2) |
| cp | = | Specific heat at constant pressure (J kg−1K−1) |
| D | = | Diameter (m) |
| D0 | = | Normalizing diameter (m) |
| D⃰ | = | Normalized diameter |
| f | = | Ratio of the cylinder-to-flat plate average heat transfer coefficient |
| Gr | = | Grashof number |
| = | Average heat transfer coefficient over length (W m−2 K−1) | |
| HTC | = | Heat transfer coefficient (W m−2 K−1) |
| Ja | = | Jakob number |
| L | = | Length (m) |
| = | Mass flow rate (kg s−1) | |
| = | Average Nusselt number over length (W m−2 K−1) | |
| = | Average Nusselt number for the referenced diameter, 40 mm (W m−2 K−1) | |
| P | = | Pressure (Pa) |
| T | = | Temperature (K) |
| = | Average temperature (K) | |
| U | = | Uncertainties |
| W | = | Mass fraction |
Greek letters
| = | Temperature rise of cooling water | |
| = | Temperature difference between the bulk and the wall | |
| = | Correction factor for the curvature effect |
Subscript
| 0 | = | Value of the referenced tube |
| a | = | Air |
| b | = | Bulk conditions |
| c | = | Cooling water |
| cyl | = | Cylinder |
| flat | = | Flat plate |
| i | = | Inlet |
| o | = | Outlet |
| s | = | Steam |
| w | = | Wall |