Numerical Investigation of Direct Contact Condensation in a Sinusoidal Pipe

Abstract Direct contact condensation (DCC) of steam in subcooled water within pipes is important for a range of industrial applications, including chemical, thermal, and nuclear power plants. This study explores the flow physics and the heat transfer mechanism at the steam–water interface in the sinusoidal horizontal pipe. The two-phase fluid flow is modeled numerically using the volume of fluid (VOF) method in OpenFOAM. The Tanasawa phase change model is used to simulate mass transfer at the steam–water interface, while the k–ε turbulence model is used to account for turbulence effects. The study analyses flow behavior, transient temperature fields, and heat flux at the steam–water interface under varying feed water flow rates and inlet temperatures. A transition from a stratified flow regime to a slug flow regime is observed during condensation. The phenomenon of bubble entrapment in the slug flow regime due to interfacial instabilities during the DCC between steam and water is also discussed. Observations reveal that the heat flux at the steam–water interface increases with an increase in the mass flowrate of the feed water and the temperature of the inlet water. The Nusselt number increases with an increase in the Jakob number and the Reynolds number.