Study on the flashing-induced deposition in steam generator tube support plate

Flashing-induced deposition poses a significant challenge in industrial heat exchange systems, where rapid pressure drops or local boiling lead to vapor generation and solute precipitation in confined regions. This mechanism is particularly critical in nuclear steam generators, where flow blockage near tube support plate (TSP) holes can compromise long-term operational safety and efficiency. To investigate this phenomenon, a three-dimensional four-channel computational fluid dynamics (CFD) model incorporating a two-fluid and phase-change approach was developed. Simulations reveal that flashing initiates at the TSP inlet, accompanied by a sharp increase in void fraction and the formation of low-pressure vortices. Variations in mass flow rate and inlet vapor quality significantly influence pressure drop and evaporation intensity, affecting bubble redistribution and pressure recovery. An empirical model was formulated to quantify flashing-enhanced deposition based on pressure-drop characteristics. The pressure-drop coefficient K follows a blockage-dependent power-law form (K = K0·Re−n), and a two-phase multiplier C = 4.84 accounts for vapor-phase effects. Model predictions show good agreement with CFD results across multiple blockage scenarios. This study not only reveals the formation mechanism of flashing-induced local deposition, but also provides theoretical support for fouling risk assessment and cleaning strategies in full-scale steam generator systems.