Pool boiling and condensation analysis for a vertical tube bundle condenser

An experimental and theoretical study is performed for the steam condensation in a vertical tube bundle passive condenser simulating PCCS condenser in the ESBWR. Four condenser tubes are submerged in a water pool where the heat from the condenser tube is removed through boiling heat transfer. Condenser tubes with a full length/diameter scale are used to obtain the condensation data with various process parameters. The comparison of tube bundle experimental data with the single tube data by both the experiments and models shows that the single tube secondary heat transfer coefficient (HTC) is between 25% - 35% less than what was recorded for the tube bundle, and the tube bundle condensation rates are slightly higher than the data from the single tube test sections due to turbulent mixing effect which increases the condensation heat removal. The turbulent mixing on the secondary side decreases the DT between pool water and condenser tube outer wall, causing an increase in secondary HTC. This increase in secondary HTC thus results in higher condensate mass flow rates. Tube bundle boundary layer model and heat and mass analogy model were then developed for the prediction of the filmwise steam condensation with noncondensable (NC) gas in a vertical tube bundle. The predictions from the models are compared with the experimental data for various complete condensation and through flow conditions and the agreement is satisfactory. The local parameters predicted by the boundary layer model and heat and mass analogy model with tube bundle pool boiling can also be predicted with the axial distance from entrance for different NC gas fractions and system pressures. (author)