Numerical investigation of heat transfer in direct contact condensation of steam to subcooled water spray

The direct contact condensation heat transfer (DCCHT) of saturated steam to subcooled water spray produced by a pressure-swirl nozzle was examined by computational fluid dynamics (CFD) in which a two-dimensional (2-D) axisymmetric swirl calculation was performed to simulate the hydraulic characteristics and the temperature profile of the water spray in the sheet region. The CFD simulations were validated by the experimental results obtained in the studies under the same operational conditions. In the simulation, the kinetic theory-based Schrage model was used for condensation flux calculation, and the interfacial area density of liquid sheet was introduced to evaluate the area of the vapor-liquid interface. The numerical simulations indicated that condensation did not significantly affect the spray cone angle, the sheet thickness and the interfacial area density although it significantly affected the sheet breakup length. Additionally, when compared with traditional film-wise condensation on solid walls, heat transfer coefficient in the DCCHT was significantly higher than that in general film-wise condensation.