In the figure shown, the system is a pure substance kept in a piston cylinder arrangement. The system is initially a two phase mixture containing 1 kg of liquid and 0.03 kg of vapour at a pressure of 100 kPa. Initially, the piston rests on a set of stops, as shown in the figure. A pressure of 200 kPa is required to exactly balance the weight of the piston and the outside atmospheric pressure. Heat transfer takes place into the system until its volume increases by 50%. Heat transfer to the system occurs in such a manner that the piston, when allowed to move, does so in a very slow (quasi-static / quasi - equilibrium) process. The thermal reservoir from which heat is transferred to the system has a temperature of 4000C. Average temperature of the system boundary can be taken as 1750C. The heat transfer to the system is 1 kJ during which its entropy increased by 10 J/K.
Specific volume of liquid (vf) and vapour (vg) phase, as well as values of saturation temperatures, are given in the table below ||||| |---|---|---|---| | Pressure (kPa) | Saturation temperature, Tsat(0C) | Vf(m3/kg) | Vg(m3/kg) | | 100 | 100 | 0.001 | 0.1 | | 200 | 200 | 0.0015 | 0.002 |
The work done by the system during the process is
