A physically based, one-dimensional three-fluid model for direct contact condensation of steam jets in flowing water.pdfVIP

International Journal of Heat and Mass Transfer 106 (2017) 1041–1050 Contents lists available at ScienceDirect International Journal of Heat and Mass Transfer journal homepage: /locate/ijhmt A physically based, one-dimensional three-?uid model for direct contact condensation of steam jets in ?owing water David Heinze a,b,?, Thomas Schulenberg b, Lars Behnke a a Mechanical Engineering, Kernkraftwerk Gundremmingen GmbH, Dr.-August-Weckesser-Str. 1, 89355 Gundremmingen, Germany b Institute for Nuclear and Energy Technologies, Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany article info Article history: Received 1 September 2015 Received in revised form 11 September 2016 Accepted 22 October 2016 Available online 11 November 2016 Keywords: Direct contact condensation Steam jet Pipe ?ow Surface renewal theory Interfacial transfer abstract A simulation model for the direct contact condensation of steam jets in ?owing water is presented. In contrast to previous empirical approaches, the model takes into account the underlying physical phenomena governing the condensation process. Condensation at the interface between the steam jet and the surrounding water is calculated according to the surface renewal theory. Entrainment of water into the steam jet is modeled based on the Kelvin–Helmholtz and Rayleigh–Taylor instability theories. The resulting steam-water two-phase ?ow is simulated based on a one-dimensional three-?uid model. An interfacial area transport equation is used to track changes of the interfacial area density due to droplet entrainment and steam condensation on droplets. The simulation results are in good qualitative agreement with published experimental data. In particular, the dependency of the steam jet length on the ?ow Reynolds number is properly reproduced. This corroborates our theory that the heat transfer coef?cient at the interface of a condensing steam jet can be linked to the water ?ow rate vi