Local Sherwood number in wall condensation on a vertical flat plate from steam and air mixtures

This paper presents a condensation heat transfer correlation which gives condensation heat fluxes qc on the primary containment vessel (PCV) wall as boundary conditions in CFD (computational fluid dynamics) analysis of thermal hydraulics in the PCV during accident conditions by using physical quantities such as the velocity ug, temperature Tg and steam mass fraction Ys of steam and air mixtures in the computation cells contacting the PCV wall. Previously, we carried out numerical simulation for forced convection (FC) condensation from steam and air mixtures on a vertical flat plate (which simulated a part of the PCV wall) by using the CFD code FLUENT. We obtained newly defined local Sherwood numbers Shy, FC for the qc, FC(Shy,FC) correlation as a function of the distance y from the condensation surface by using the computed ug, Tg and Ys values, and we proposed a Shy,FC correlation. Here, we obtained local Sherwood numbers Shy,NC for the qc, NC(Shy,NC) correlation of natural convection (NC) condensation heat fluxes qc,NC as a function of the distance y by using the computed ug, Tg and Ys values from the previous results of our numerical simulation, and proposed a Shy,NC correlation. The qc,NC(Shy,NC)/qc, CFD values (where qc,CFD is the qc values by CFD analysis) were within 1.0 ± 0.2 in the range of the dimensionless distance y+ = 10–1000 for Ys,in = 0.226, 0.453, and 0.68 at the inlet of the flow channel and the distance in the flow direction of x = 4.0, 5.0, and 5.95 m.