3.30   One kg of water initially is at the critical point.

(a)    If the water is cooled at constant-specific volume to a pressure of 30 bar, determine the quality at the final state.

(b)   If the water undergoes a constant-temperature expansion to a pressure of 30 bar, determine the specific volume at the final state, in m3/kg.

Show each process on a sketch of the T–y  diagram.

3.31   As shown in Fig. P3.31, a cylinder fitted with a piston is filled with 600 lb of saturated liquid ammonia at 45°F. The piston weighs 1 ton and has a diameter of 2.5 ft. What is the volume occupied by the ammonia, in ft3? Ignoring friction, is it necessary to provide mechanical attachments, such as stops, to hold the piston in place? Explain.

 

3.23   Ammonia, initially saturated vapor at 24°C, undergoes a constant-specific volume process to 200 kPa. At the final state, determine the temperature, in °C, and the quality. Locate each state on a sketch of the T–y diagram.

3.24   Water contained in a closed, rigid tank, initially saturated vapor at 200°C, is cooled to 100°C. Determine the initial and final pressures, each in bar. Locate the initial and final states on sketches of the p–y and T–y diagrams.