2 A container with an initial volume of 15 litres is sealed by a free lid...

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2 A container with an initial volume of 15 litres is sealed by a free lid (lid mass and friction are neglected). It is initially filled with water (HO) vapour at 120C. The environmental pressure is 1 bar. The molar mass of water is 18.0 kg/kmol. The specific volumes of HO at 1 bar pressure are given in the following table. 0 50 80 0.00100 0.00101 0.00103 Temperature T (C) Specific volume v (m/kg) Tsat=99.6 120 200 V=0.00104 Vg=1.694 1.793 2.172 a) Sketch the saturation curve in a T-v diagram. Indicate liquid zone, gas zone, two- phase zone, critical point and the constant pressure lines of p=1 bar and p=2 bar in the diagram (not to scale). [5 marks] b) If the temperature decreases resulting from heat transfer to the surroundings at the constant pressure (free lid) of 1 bar, at what volume will liquid water start to appear? (Note: if ideal gas equation is used, justify why it is valid). [4 marks] c) If the volume is further reduced at the constant pressure of 1 bar until the volume becomes 6 litres, determine the temperature and the dryness fraction. [5 marks] 2 A container with an initial volume of 15 litres is sealed by a free lid (lid mass and friction are neglected). It is initially filled with water (HO) vapour at 120C. The environmental pressure is 1 bar. The molar mass of water is 18.0 kg/kmol. The specific volumes of HO at 1 bar pressure are given in the following table. 0 50 80 0.00100 0.00101 0.00103 Temperature T (C) Specific volume v (m/kg) Tsat=99.6 120 200 V=0.00104 Vg=1.694 1.793 2.172 a) Sketch the saturation curve in a T-v diagram. Indicate liquid zone, gas zone, two- phase zone, critical point and the constant pressure lines of p=1 bar and p=2 bar in the diagram (not to scale). [5 marks] b) If the temperature decreases resulting from heat transfer to the surroundings at the constant pressure (free lid) of 1 bar, at what volume will liquid water start to appear? (Note: if ideal gas equation is used, justify why it is valid). [4 marks] c) If the volume is further reduced at the constant pressure of 1 bar until the volume becomes 6 litres, determine the temperature and the dryness fraction. [5 marks]