Calculate quantity of steam in the vessel - thermodynamics:
A closed metallic boiler drum having capacity of 0.24m3 contains steam at pressure of 11bar and a temperature of 200ºC. Calculate quantity of steam in the vessel. At what value of pressure in the vessel will the steam be dry and saturated if vessel is cooled?
Sol.: Given that:
Capacity of drum V_{1} = 0.24m3
Pressure of steam P_{1} = 11bar
Temperature of steam T_{1} = 200ºC
At pressure 11bar from the super heated steam table
At 10 bar and T = 200ºC; Å =0.2060m3/kg
At 12 bar and T = 200ºC; Å =0.1693 m3/kg
By using linear interpolation method:
(Å - 0.2060)/(0.1693 - 0.206) = (11 - 10)/(12 - 10)
Å = 0.18765 m3/kg
Quantity of steam = V/Å = 0.24/0.18765 = 1.2789 kg
From the Saturated steam table
At 11bar; T_{sat} = 184.09ºC
2000C > 184.09ºC
That is, steam is superheated
If vessel is cooled until the steam becomes dry saturated, its volume will remain same but the pressure of it will change.
From Saturated steam table; corresponding to Åg = 0.18765, pressure is 1122.7KPa .......ANS