Condensation regime diagram for supersonic and subsonic steam jet condensation in water flow in a vertical pipe

Highlights: • Supersonic and subsonic steam jet condensation in water flow is studied visually. • Strong correlation between condensation regimes and pressure oscillation is found. • Scaled steam mass flux is irrelevant to the transitional lines in the regime diagram. • Condensation regime diagram is developed to describe the four condensation regimes. • Condensation regime diagram at low ambient pressure can be applied to high pressure. - Abstract: An experimental research is performed to investigate the condensation regime diagram of supersonic and subsonic steam jet condensation in water flow in pipes. The original images of the jet plume are recorded using a visualization window and a high-speed camera. The jet condensation regimes are basically categorized into four types, including Chugging, Oscil-I, Oscil-II and Stable regimes, primarily based on the transient evolution of geometrical profile of the jet plume. And the average geometrical shape of the jet plume is found to shrink gradually with increase of ambient pressure. The stand deviation of pressure oscillation is highly correlated to jet condensation regimes, so it can be applied to quantitatively categorize different regimes. The steam mass flux, scaled by critical steam mass flux at different ambient pressure, is found to be irrelevant to the transitional lines among Chugging, Oscil-I, and "Stable or Oscil-II" regimes in the condensation regime diagram. Furthermore, the Oscil-II regime can be simply isolated from the "Stable or Oscil-II" regime via comparison of the standard deviation of pressure oscillation in this two regimes. Therefore, the jet condensation regime diagram obtained from low ambient pressure could be applied to conditions of elevated ambient pressure.