Question

1. Four kg of water is placed in an enclosed volume of 1m3. Heat is added until the temperature is 150°C. Find ( a ) the pressure, ( b )the mass of vapor, and ( c ) the volume of the vapor.

Answer 1

Answer:

476.16 kPa; 2.544kg;0.998m^3

Explanation:

Solution:

a)We use the table of Saturated water—Temperature.Inthe quality region the pressure is given as p = 476.16kPa

b) To find the mass of the vapor we must determine the quality.We use the next equation:

                                             v=vp+x(vg-vp)

Then,

          0.25m^3/kg=0.001091m^3/kg+x(0.39248−0.001091)m^3/kg

                              0.25=0.001091+0.391389x

                              0.391389x=0.25−0.001091

                                 0.391389x=0.248909

                   x=0.248909(m^3/kg)/0.391389(m^3/kg)

                                       x=0.63596

Using the relationship of x=Mg/M, we find the vapor mass

                   Mg=xm=0.63596×4kg=2.544kg

c) The volume of the vapor is found from

               vg=vgmg=2.544kg×0.39248m^3/kg=0.998m^3