3.70 Referring to Fig. P3.70, water contained in a piston- cylinder assembly, initially at 1.5 bar and a quality of 20%, is heated at constant pressure until the piston hits the stops. Heating then continues until the water is saturated vapor. Show the processes of the water in series on a sketch of the T-y diagram. For the overall process of the water, evaluate the work and heat transfer, each in kJ/kg. Kinetic and potential effects are negligible.
3.71 A piston-cylinder assembly contains 2 lb of water, initially at 300°F. The water undergoes two processes in series: constant-volume heating followed by a constant-pressure process. At the end of the constant-volume process, the pressure is 100 lbf/in.2 and the water is a two-phase, liquid- vapor mixture with a quality of 80%. At the end of the constant-pressure process, the temperature is 400°F. Neglect kinetic and potential energy effects.
(a) Sketch T-y and p-y diagrams showing key states and the processes.
(b) Determine the work and heat transfer for each of the two processes, all in Btu.
