thanks for the links, before start calcul first I think all work interaction is of the expansion type and only thermal energy change is significant.
For the initial property, I know the volume and pressure. with this information I go to the "saturated water and steam table" the look the properties of this condition
I find for 5 bar presasure :
151.85 C boiling point, 2.669 kg/m3 steam density, 2.3289 kJ/kg K specific heat, 2747.54 kJ/kg specific enthalpy of steam, 640.12 kJ/kg specific enthalpy of liquid water, 2107.42 kJ/kg latent heat of vaporization
- the mass of steam in the system ? steam density x volume initiale <=> 2.669 kg/m3x 0.8 m3= 2.1352 kg for the mass of steam
I'm here, the problem is I didn't understand what means "80% dry to a final state of 2 bar"
thanks for the help