Numerical modeling of condensing two-phase flows

A methodology for modeling condensation in the presence of noncondensables, based on the stagnant film (Couette flow) model, and fully compatible with the numerical algorithm in the RELAP5 computer program, and with the stability-enhancing two-step (SETS) and the interphase slip (IPSA) algorithms, has been developed. The methodology treats the coupling between the heat and mass transfer processes rigorously, and allows for an implicit representation of the exchange terms at the gas-liquid interphase, without requiring any modification to the basic numerical algorithms. The numerical solution schemes in RELAP5 and SETS algorithms are reviewed and the way to incorporate the developed condensation model into these algorithms is shown. Accordingly, the RFLAP5 / MOD3 computer code is modified, and is validated successfully against available experimental data.