Find the work required for the process.

3 kg of steam in a piston -cylinder device at 400 kPa and 175 degree Celsius undergoes a mechanically reversible ,isothermal  compression to a final pressure such that the steam becomes just saturated.What is the work required for the process.

$$T=175^{\circ}C \\v=0.503\;m^{3}/kg \\S=7.055\;kJ/kgK \\P=400\;kPa \\u=2606\;kJ/kg$$

For saturated vapour

$$v=0.216\;m^{3}/kg \\u=2579\;kJ/kg \\S=6.622\;kJ/kgK$$

Asked on 29th September 2019 in
$q=T\left ( s_{2} -s_{1}\right )$
$$\\=\left ( 175+273 \right )\left ( 6.622-7.055 \right ) \\=-193.983 \\W=q-\left ( u_{2}-u_{1} \right ) \\=\left ( -193.984-\left ( 2579-2606 \right ) \right )\times 2 \\= -500.94\;kJ$$