Flow structure during steam condensation in sub-cooled water in a large vertical pipe using wire-mesh sensors

The structure of a steam-water flow in a vertical pipe of 195.3 mm inner diameter was studied using novel wire-mesh sensors for high-pressure / high-temperature operation (max. 7 MPa / 286 °C). Tests were carried out at pressures of 1 and 2 MPa under nearly adiabatic conditions as well as with slightly sub-cooled water. The evolution of radial gas fraction profiles and bubble-size distributions along the pipe in a high-pressure steam-water flow was measured for the first time. The experimental data allow to correlate the intensity of steam condensation in contact with sub-cooled water with the structure of the interfacial area and the bubble size distribution, which is very important for the model development.