1. Propane is contained in a closed, rigid container with a volume of 10 m3. Initially the pressure and temperature of the propane are 8 bar and 80°C, respectively. The temperature drops as a result of energy rejected by heat transfer to the surroundings. Determine the temperature at which condensation first occurs, in °C, and the fraction of the total mass that has condensed when the pressure reaches 5 bar. What is the volume, in m3, occupied by saturated liquid at the final state?
2. Water vapor is cooled in a closed, rigid tank from 520°C and 100 bar to a final temperature of 270°C. Determine the final pressure, in bar, and sketch the process onT-y and p-y diagrams.
3. Ammonia contained in a piston-cylinder assembly, initially saturated vapor at 0°F, undergoes an isothermal process during which its volume (a) doubles, (b) reduces by a half. For each case, fix the final state by giving the quality or pressure, in lbf/in.2, as appropriate. Locate the initial and final states on sketches of the p-y and T-y diagrams.
4. Two lb of water vapor in a piston-cylinder assembly is compressed at a constant pressure of 250 lbf/in.2 from a volume of 6.88 ft3 to a saturated vapor state. Determine the temperatures at the initial and final states, each in °F, and the work for the process, in Btu.