Generalized draining film model equation set to execute an exact numerical solution for cfd code validation

Abstract

The Westinghouse Advanced Passive PWR AP-600 and AP- 1000 are pressurized water reactors (PWR) with advanced passive safety systems. Most recognize the passive containment cooling system (PCCS) as being one of the most important concepts for advanced passive safety systems. The steel containment structure consists of a vertical right-circular cylinder capped with oblate spheroids at both ends. Following a postulated design-base-accident (DBA), an outside cold liquid-water spray is injected on the apex of the spheroidal dome. The resulting liquid-film drains under gravitational body forces over the outside dome surface and down the cylinder surface. This PCCS removes heat from the containment interior to reduce potentially damaging pressure and temperature loads. To facilitate model validation we have developed an exact numerical solution (ENS) for the one-dimensional steady-state liquid film flow over an ellipsoidal-domed cylinder. Although the ENS assumes constant containment wall temperature and outside ambient air temperature, it can incorporates any generalized heat transfer correlation between the containment surface and liquid film as well as any generalized heat and mass (evaporation) transfer correlations between the film and outside ambient air. ENS results for draining liquid water films clearly present the coupling effects of heat and mass transfer.