Answer to Question #78727 in Molecular Physics | Thermodynamics for Abhinav

Question

Saturated steam at 10 bar is cooled at constant pressure until its dryness fraction becomes 50%. The change in temperature of steam in ◦C is ______

Answer 1

At 1 MPa or 10 bar,
Boiling point of water = 179.88 °C
Specific volume of steam= 0.194 m3/kg
Specific volume of water = 0.001 m3/kg
Therefore volume occupied by steam at 300 °C (573 K) and 1 MPa = 0.194 m3
When steam is cooled, there are two types of heat transfer:
1) Normal heat transfer, where steam temperature reduces from 300 °C to 179.88°C. Assuming that steam follows ideal gas law.
As per ideal gas law, at constant pressure, volume is directly proportional to temperature.
2) Latent heat transfer till half of steam is condensed.
Final temperature will be 179.88 °C (452.88 K), change in temperature will be 120.12 °C