Steam Table question

[morry]

Ok, using steam tables, calculate the specific entropy of steam with dryness fraction 0.63 and pressure of 2MPa.

Can someone suggest how Id go about this?

Thanks.

[Astronuc]

If it has a quality (dryness fraction), x = 0.63, it is saturated steam at 2 MPa.

let y be a property, e.g. specific volume, v, specific enthalpy, h, specific internal energy, u, or specific entropy, s.

In a two phase system, each phase has these properties,

yf or yl , where f denotes fluid and l liquid

and

yg or yv , where g denotes gas and v vapor.


The property of the mixture is just the mass weighted sum of the liquid and vapor property.

y = (1-x) yf + x yg, or

y = yf + x yfg,

where yfg = yg - yf

[morry]

Thanks Astronuc, I forgot that you could find entropy on the tables.