ChE 243: Engineering Thermodynamics Assignment 3: Written Portion Written Problem A piston-cylinder assembly has the following components: A piston of negligible mass and a cross-sectional area of 1 m. A pair of stops which fix the minimum internal volume of the cylinder at 3600 L. A linear spring with spring constant k = 250 kN/m. It is made such that when the piston is resting on the stops, the spring is in contact with both the piston and the roof of the assembly, but remains stress-free (i.e. neither compressed nor stretched). The atmospheric pressure is constant at 100 kPa. Patm = 100 kPa State 1 water Initially, with the piston sitting on the stops, the cylinder contains 2 kg of water at 10 kPa (State 1). Heat is now added to the water, causing its pressure to increase. State 2 is reached when the piston just begins to separate from the stops. From State 2, heat continues to be added until the piston rises a distance of 40 cm, at which point the water is in State 3. (a) What is the temperature of the water in State 1 (in C)? Explain. (b) What is the temperature of the water in State 2 (in C)? (c) What is the temperature of the water in State 3 (in C)? (d) Sketch the process (from State 1 to State 3) on a P-v diagram. You do not need to include numerical values of P or v, but show clearly the positions of the three states relative to the saturation lines. (e) Calculate the boundary work (in kJ) in going from State 1 to State 3.