Poly-disperse simulation of condensing steam-water flow inside a large vertical pipe

• Condensing steam-water flow in vertical pipe simulated.
• The Inhomogeneous MUSIG poly-disperse approach used.
• Satisfactory agreement with the measurement achieved.
• Effect of phase change, coalescence/breakup on bubble size considered.
• Effect of interphase heat transfer coefficient correlations investigated.

The condensation of saturated steam bubbles in sub-cooled water inside a vertical pipe was studied by poly-disperse CFD simulations. Six test cases with varied pressure, liquid sub-cooling and diameter of the gas injection orifices were simulated. Baseline closures presented for non-drag forces in previous work were found to be reliable also in non-isothermal cases. The effect of bubble coalescence and breakup is over-weighting in the region close to steam injection in case of small orifice diameter. With the increase of orifice diameter, breakup becomes dominant in determining bubble size change. The effect of interphase heat transfer coefficient correlations was investigated. The widespread Ranz–Marshall correlation was found to under-estimate the condensation rate, especially at high pressure levels. In contrast, satisfying agreement with the experimental data was obtained by the Tomiyama correlation.