A partition divides an insulated tank into two parts Figure

A partition divides an insulated tank into two parts (Figure 1). One part of the tank contains 2.5 kg of compressed liquid water at 65°C and 600 kPa while the other part is evacuated. The partition is then removed, and the water expands to fill the entire tank. Determine the final temperature of the water and the volume of the tank for a final pressure of 10 kPa

H₂O Evacuated partition

Solution

As the process occurs in an insulated tank and there is no change in internal energy in the process,As the internal energy is a function of temperature,so the final temperature will remain same. i.e 65-degree Centigrade.

for 600 Kpa the corresponding saturation temperature is 158 degree Celcius, so the liquid is compressed.

for 10 Kpa the corresponding saturation temperature is 45.8 degree Celcius, so there is a change in phase in the process and it is in vapour state.

For 2nd Condition

Final Temperature= 65 degree Celcius

Final Pressure = 10 Kpa

from the steam table , v(g)= 14.67 m3/kg

and given the mass rate is 2.5 kg

So the final volume will be= v(g)*m= 14.67*2.5=36.675 m3