Answer to Question #69567 in Mechanical Engineering for MAHESH SHARMA

Question

Q. 1 A two-phase liquid-vapour mixture of water, initially at a pressure of 5 bar and dryness fraction of 0.5, is heated in a closed rigid tank of volume 0.2 m3 until only saturated water vapour remains. The approximate mass of the water and the final pressure will be respectively
1.064 kg, 10.5 bar
2.064 kg, 10.5 bar
1.064 kg, 1.5 bar
2.064 kg, 1.5 bar

Q.2 A piston-cylinder device fitted with stops as shown in the figure initially contains one kg of water at 400 kPa and 300°C. Heat is rejected from the cylinder at constant pressure until water exists in the cylinder as a saturated vapour and the piston rests on the stops. Heat rejection from the cylinder continues until the pressure is 100 kPa. Calculate the dryness fraction at the end of process.

0.8788
0.4748
0.2728
0.6768