Pressurizer: impact of sourge enthalpy
As for any standard volume, a unique hl
enthalpy is considered for the liquid phase, meaning that the liquid entering from the sourge line is mixed with the whole liquid phase. Usually the Cex.h
is quite lower than the saturation enthalpy: inlet flow than mean a significant decrease of the liquid phase enthalpy and finally of the pressurizer pressure. This is not consistent with some expertimental data (see the Shippingport article hereafter), as seen by @viola.ferrara.
In fact, the pressurizer is generally thermally stratified and the cold water entering from the bottom has little effect on the enthalpy of the water at the surface (interface between liquid and vapour). The thermal equilibrium of the liquid phase is eventually achieved beacause of thermal diffusion, a quite long term phenomena compared to other transients.
Two solutions:
- Quick one: to add a boolean to chose whether instantaneous mixing has to be used or to consider null the contribution of the sourge line to the energy balance equation.
- Long term one: to model two liquid zones (the near to the surface one + the bottom one) and model the thermal coupling of the zones with thermal diffusion.
Potentially, a more simplified model with equilibrium phases could also be developed (rather as an option of the current module).