1.08 lbm of water fills a container whose volume is 2.08 ft3. The pressure in the container is 100 psia. Calculate the total internal energy and enthalpy in the container. Use data from the steam tables.

661 btu/lbm, 698 btu/lbm

Explanation:

solution:

First the total specific volume of the mixture is determined from the mass and volume:

α=V/m

=2 ft^3/lbm

Next, the quality of the mixture is obtained from the specific volumes of the constituents at the given pressure using data from:

q = (α-α_liq100) / (α_vap-α_liq) 100

= (2-0.01774) / (4.432-0.01774)

=0.449

Now the enthalpy and internal energy are determined from the quality:

u=u_liq100+qu_evap100

=661 btu/lbm

h=h_liq100+qh_evap100

=698 btu/lbm