4. A two-phase, liquid–vapor mixture of H2O, initially at x = 30 % and a pressure of 100 kPa, is contained in a piston – cylinder assembly, as shown in Fig 4. The mass of the piston is 10 kg, and its diameter is 15 cm. The pressure of the surroundings is 100 kPa. As the water is heated, the pressure inside the cylinder remains constant until the piston hits the stops. Heat transfer to the water continues at constant volume until the pressure is 150 kPa. Friction between the piston and the cylinder wall and kinetic and potential energy effects are negligible. Present the process on the P-v diagram. For the overall process of the water, determine the work and heat transfer, each in kJ.
Use the following conversions where necessary:1hp = 745.7W; ρwater = 1000 kg/m3;
ρmercury = 13600 kg/m3; 1 atm = 101.325 kPa; Cp (water) = 4.18 kJ/kg °C; g = 9.81m/s2;
For properties of air, use R = 0.287 kJ/kg K; Cv (air) = 0.718 kJ/kg K; Cp (air) =1.005 kJ/kg K
4. A two-phase, liquid–vapor mixture of H2O, initially at x = 30 % and a pressure of 100 kPa, is contained in a piston – cylinder assembly,
as shown in Fig 4. The mass of the piston is 10 kg, and its diameter is 15 cm. The pressure of the surroundings is 100 kPa. As the water is heated, the pressure inside the cylinder remains constant until the piston hits the stops. Heat transfer to the water continues at constant volume until the pressure is 150 kPa. Friction between the piston and the cylinder wall and kinetic and potential energy effects are negligible. Present the process on the P-v diagram. For the overall process of the water, determine the work and heat transfer, each in kJ.
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