• CFD
• termofluidodinamica
• idrogeno
• condensazione

The present work is the result of a six months stage in the Labotatoire d'études des Transferts et Mécanique des Fluides in CEA Saclay and is focused on the analysis of the effects of a light incondensable gas (helium to replace hydrogen) on the phenomenon of steam condensation along vertical wall.

A diffusive model able to deal with ternary mixtures has been developed. An entire section is devoted to the validation of this model, addressing laminar flow in forced convection and taking as reference analytical solutions.

Then, a comparison between air-steam-hydrogen and air-steam-helium mixtures has been performed. Good agreement between the two mixtures properties was found in relation to the total heat flux and the condensing mass flux, showing that the substitution of hydrogen with helium (which is usually made in experimental facilities) grants a really good approximation.

Finally, the validation of a turbulent model for the mentioned ternary mixtures was performed. This step allows to compare the code results with reference experimental data, which come from the COPAIN program, selecting the cases in which the forced convection phenomena are dominant. The analysis of the results has shown a good behavior of the diffusive model, pointing out some limitations of the adopted turbulent model.